Document Anaheim_doc_3b71189ad4

Appendix B Orange County Water District Groundwater Management Plan 2009 Update ---PAGE BREAK--- 2009 UPDATE Groundwater Management Plan Orange County Water District ---PAGE BREAK--- ---PAGE BREAK--- ORANGE COUNTY WATER DISTRICT GOUNDWATER MANAGEMENT PLAN 2009 UPDATE Greg Woodside, PG CHg Marsha Westropp, Senior Watershed Planner July 9, 2009 ---PAGE BREAK--- ---PAGE BREAK--- PAGE NUMBER TABLE OF CONTENTS SECTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE I EXECUTIVE SUMMARY 1 INTRODUCTION 1.1 HISTORY OF 1.2 GROUNDWATER 1.3 PUBLIC EDUCATION PROGRAMS 1.4 PREPARATION OF THE OCWD GROUNDWATER MANAGEMENT PLAN 1.5 OCWD ACCOMPLISHMENTS, 2004-2008 1.6 PUBLIC 1.7 COMPLIANCE WITH CALIFORNIA WATER 1.8 GROUNDWATER MANAGEMENT GOALS AND 1.8.1 PROTECT AND ENHANCE GROUNDWATER QUALITY 1.8.2 PROTECT AND INCREASE THE BASIN’S SUSTAINABLE YIELD IN A COST EFFECTIVE 1.8.3 INCREASE OPERATIONAL EFFICIENCY 2 BASIN HYDROGEOLOGY 2.1 DESCRIPTION OF BASIN HYDROGEOLOGY 2.1.1 FOREBAY AND PRESSURE AREAS 2.1.2 GROUNDWATER SUBBASINS, MESAS, AND 2.2 DETERMINATION OF TOTAL BASIN 2.3 WATER 2.3.1 MEASURED 2.3.2 UNMEASURED 2.3.3 GROUNDWATER 2.3.4 SUBSURFACE OUTFLOW 2.4 GROUNDWATER ELEVATION AND STORAGE CALCULATION...................2-11 2.5 ACCUMULATED OVERDRAFT 2.5.1 DEVELOPMENT OF NEW METHODOLOGY 2.6 ELEVATION TRENDS 2.7 LAND 2.8 GROUNDWATER MODEL DESCRIPTION 2.8.1 MODEL 2.8.2 MODEL ADVISORY PANEL 2.8.3 TALBERT GAP 3 GROUNDWATER MONITORING 3.1 3.2 COLLECTION AND MANAGEMENT OF MONITORING DATA 3.3 WATER SAMPLE COLLECTION AND 3.4 PRODUCTION AND GROUNDWATER ELEVATION MONITORING 3.5 WATER QUALITY MONITORING 3.5.1 DRINKING WATER 3.5.2 MONITORING FOR CONTAMINANTS IN THE BASIN 3.6 SEAWATER INTRUSION MONITORING AND PREVENTION 3.7 MONITORING QUALITY OF RECHARGE WATER ---PAGE BREAK--- PAGE NUMBER TABLE OF CONTENTS SECTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE II 3.7.1 SANTA ANA RIVER WATER QUALITY 3.7.2 REPLENISHMENT WATER FROM METROPOLITAN 3.7.3 GROUNDWATER REPLENISHMENT 3.7.4 INTEGRATED GROUNDWATER AND SURFACE WATER 3.8 PUBLICATION OF DATA 4 RECHARGE WATER SUPPLY 4.1 RECHARGE OPERATIONS 4.1.1 PRADO BASIN 4.1.2 RECHARGE FACILITIES IN ANAHEIM AND 4.2 SOURCES OF RECHARGE WATER 4.2.1 SANTA ANA 4.2.2 SANTIAGO CREEK 4.2.3 PURIFIED WATER 4.2.4 IMPORTED 4.3 RECHARGE STUDIES AND 4.3.1 OCWD RECHARGE ENHANCEMENT WORKING GROUP 4.3.2 COMPUTER MODEL OF RECHARGE 4.4 IMPROVEMENTS TO RECHARGE FACILITIES 4.4.1 RECHARGE FACILITIES IMPROVEMENTS 2004-2008..............4-21 4.5 POTENTIAL PROJECTS TO EXPAND RECHARGE OPERATIONS 5 WATER QUALITY MANAGEMENT 5.1 GROUNDWATER QUALITY 5.1.1 OCWD GROUNDWATER PROTECTION 5.1.2 WATER QUALITY TREATMENT GOALS FOR GROUNDWATER PROGRAMS 5.1.3 REGULATION AND MANAGEMENT OF CONTAMINANTS...............5-2 5.1.4 LAND USE AND DEVELOPMENT 5.1.5 DRINKING WATER SOURCE ASSESSMENT AND PROTECTION PROGRAM 5.1.6 WELL CONSTRUCTION 5.1.7 WELL CLOSURE PROGRAM FOR ABANDONED WELLS 5.2 SALINITY 5.2.1 SOURCES OF 5.2.2 REGULATION OF SALINITY 5.2.3 SALINITY IN THE GROUNDWATER 5.2.4 ECONOMIC IMPACTS OF INCREASING 5.2.5 SALINITY MANAGEMENT PROJECTS IN THE UPPER WATERSHED 5.2.6 OCWD SALINITY MANAGEMENT AND REMEDIATION PROGRAMS 5.2.7 SEAWATER INTRUSION 5.3 NITRATE MANAGEMENT 5.3.1 SOURCES OF NITRATES ---PAGE BREAK--- PAGE NUMBER TABLE OF CONTENTS SECTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE III 5.3.2 REGULATION OF 5.3.3 OCWD NITRATE MANAGEMENT AND REMEDIATION 5.4 COLORED GROUNDWATER MANAGEMENT 5.4.1 OCCURRENCE OF COLORED WATER IN THE BASIN 5.5 ORGANIC CONTAMINANTS 5.5.1 5.5.2 VOLATILE ORGANIC 5.5.3 NDMA 5.5.4 1,4-DIOXANE 5.6 5.7 CONSTITUENTS OF EMERGING 5.8 GROUNDWATER QUALITY IMPROVEMENT PROJECTS 5.8.1 NORTH BASIN GROUNDWATER PROTECTION PROJECT..........5-25 5.8.2 SOUTH BASIN GROUNDWATER PROTECTION PROJECT..........5-25 5.8.3 MTBE 5.8.4 IRVINE 5.8.5 TUSTIN 5.8.6 GARDEN GROVE NITRATE 5.8.7 RIVER VIEW GOLF COURSE 5.8.8 COLORED WATER 5.9 BEA EXEMPTION FOR IMPROVEMENT PROJECTS 6 INTEGRATED MANAGEMENT OF PRODUCTION AND 6.1 GENERAL MANAGEMENT 6.2 COOPERATIVE EFFORTS TO PROTECT WATER SUPPLIES AND WATER QUALITY 6.2.1 SANTA ANA WATERSHED PROJECT AUTHORITY (SAWPA)......6-1 6.2.2 WATER QUALITY AND NATURAL RESOURCE PROTECTION IN THE PRADO BASIN 6.2.3 CHINO BASIN INTEGRATED PLANNING 6.2.4 COOPERATIVE EFFORTS IN ORANGE 6.2.5 COOPERATIVE EFFORTS IN OCWD SERVICE 6.3 SUPPLY MANAGEMENT 6.3.1 USE OF RECYCLED WATER 6.3.2 WATER CONSERVATION 6.3.3 CONJUNCTIVE USE AND WATER 6.4 WATER DEMANDS 6.5 BASIN OPERATING RANGE 6.6 BALANCING PRODUCTION AND RECHARGE 6.7 MANAGING BASIN PUMPING 6.7.1 METHODOLOGY FOR SETTING THE BASIN PRODUCTION 6.7.2 BASIN PRODUCTION LIMITATION 6.8 DROUGHT ---PAGE BREAK--- PAGE NUMBER TABLE OF CONTENTS SECTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE IV 6.8.1 MAINTAINING WATER IN STORAGE FOR DROUGHT CONDITIONS 6.8.2 BASIN OPERATION DURING 7 FINANCIAL MANAGEMENT 7.1 BACKGROUND FINANCIAL 7.2 OPERATING 7.2.1 GENERAL FUND 7.2.2 DEBT 7.2.3 WATER 7.2.4 NEW CAPITAL EQUIPMENT 7.2.5 REFURBISHMENT AND REPLACEMENT FUND 7.3 OPERATING REVENUES 7.3.1 REPLENISHMENT 7.3.2 PROPERTY 7.3.3 OTHER MISCELLANEOUS 7.4 7.4.1 RESERVE POLICIES 7.4.2 DEBT SERVICE 7.5 CAPITAL IMPROVEMENT 8 RECOMMENDATIONS 9 REFERENCES APPENDICES APPENDIX A DOCUMENTS REGARDING PUBLIC PARTICIPATION APPENDIX B REQUIRED AND RECOMMENDED COMPONENTS FOR GROUNDWATER MANAGEMENT PLANS APPENDIX C GOALS AND MANAGEMENT OBJECTIVES DESCRIPTION AND LOCATION APPENDIX D REPORT ON EVALUATION OF ORANGE COUNTY GROUNDWATER BASIN STORAGE AND OPERATIONAL STRATEGY, OCWD, FEBRUARY 2007 APPENDIX E OCWD MONITORING WELLS APPENDIX F ACRONYMS AND ABBREVIATIONS ---PAGE BREAK--- FIGURE LIST OF FIGURES PAGE 1-1 ORANGE COUNTY WATER DISTRICT 1-2 SANTA ANA RIVER WATERSHED 1-3 SANTA ANA RIVER LOOKING UPSTREAM IN ANAHEIM AND 1-4 GROUNDWATER PRODUCTION 1961-2008 1-5 RETAIL WATER AGENCIES IN ORANGE 2-1 DWR BULLETIN 118 GROUNDWATER 2-2 ORANGE COUNTY GROUNDWATER BASIN 2-3 GEOLOGIC CROSS-SECTION THROUGH ORANGE COUNTY GROUNDWATER BASIN ..2-4 2-4 DISTRIBUTION OF GROUNDWATER PRODUCTION 2-5 RELATIONSHIP BETWEEN BASIN STORAGE AND ESTIMATED 2-6 JUNE 2008 WATER LEVELS 2-7 WATER LEVEL 2-8 ACCUMULATED BASIN 2-9 PRINCIPAL AQUIFER HISTORICAL GROUNDWATER ELEVATION PROFILES..............2-16 2-10 AVERAGE PRINCIPAL AQUIFER GROUNDWATER ELEVATIONS FOR THE FOREBAY, TOTAL BASIN, AND COASTAL 2-11 LOCATION OF LONG-TERM GROUNDWATER ELEVATION HYDROGRAPH 2-12 WATER LEVEL HYDROGRAPHS OF WELLS A-27 AND 2-13 WATER LEVEL HYDROGRAPHS OF WELLS SAR-1 AND OCWD-CTG-1 2-14 BASIN MODEL EXTENT 2-15 MODEL DEVELOPMENT 2-16 BASIN MODEL CALIBRATION 2-17 CALIBRATION HYDROGRAPH FOR MONITORING WELL AM-5A 2-18 CALIBRATION HYDROGRAPH FOR MONITORING WELL 2-19 CALIBRATION HYDROGRAPH FOR MONITORING WELL GGM-1 2-20 TALBERT GAP MODEL AND BASIN MODEL 2-21 TALBERT GAP MODEL AQUIFER LAYERING SCHEMATIC 3-1 PRODUCTION WELL 3-2 OCWD MONITORING WELL 3-3 OCWD STATE CERTIFIED NEW 3-4 THREE COMMON MONITORING WELL DESIGNS 3-5 MULTIPORT WELL DESIGN DETAIL 3-6 DUAL BOOM WATER QUALITY SAMPLING 3-7 EXAMPLES OF SEASONAL WELL PUMPING 3-8 GROUNDWATER AND SURFACE SITE SAMPLES COLLECTED BY 3-9 SEAWATER BARRIER 3-10 LANDWARD MOVEMENT OF 250 MG/L CHLORIDE CONCENTRATION CONTOUR......3-13 3-11 EXAMPLE CHLORIDE CONCENTRATION TREND 3-12 OCWD SURFACE WATER MONITORING LOCATIONS ABOVE PRADO DAM 4-1 OCWD RECHARGE FACILITIES IN ANAHEIM AND 4-2 PRADO DAM AND OCWD PRADO 4-3 MAXIMUM CONSERVATION STORAGE ELEVATIONS ALLOWED BEHIND PRADO DAM.4-4 4-4 INFLATABLE DAM ON THE SANTA ANA RIVER 4-5 SAND LEVEES ON THE SANTA ANA 4-6 CLEANING OF RECHARGE 4-7 BURRIS 4-8 SANTIAGO CREEK STORAGE AND RECHARGE AREAS 4-9 SANTA ANA RIVER FLOWS AT PRADO GROUNDWATER MANAGEMENT PLAN 2009 UPDATE i ---PAGE BREAK--- FIGURE LIST OF FIGURES PAGE GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ii 4-10 PRECIPITATION AT SAN 4-11 STORMFLOW RECHARGED IN THE BASIN 4-12 NET INCIDENTAL 4-13 GROUNDWATER REPLENISHMENT SYSTEM 4-14 ANNUAL RECHARGE OF IMPORTED WATER FROM MWD, 1937-2008 5-1 GROUNDWATER MANAGEMENT ZONES 5-2 TDS IN GROUNDWATER PRODUCTION 5-3 TDS IN A POTABLE SUPPLY WELL (SA-16/1) 5-4 ANNUAL ECONOMIC BENEFITS OF 100 MG/L SALINITY DECREASE IMPORTED WATER SUPPLIES 5-5 ANNUAL ECONOMIC BENEFITS OF 100 MG/L SALINITY DECREASE GROUNDWATER AND 5-6 TALBERT BARRIER INJECTION WATER – TDS TOTAL FLOW WEIGHTED AVERAGE TDS OF ALL SOURCE 5-7 PRADO 5-8 AREAS WITH ELEVATED NITRATE 5-9 PERCENT OF WELLS MEETING THE DRINKING WATER NITRATE STANDARD (MCL) 2007 AVERAGE NITRATE 5-10 CROSS-SECTION OF AQUIFERS SHOWING COLORED WATER AREAS 5-11 EXTENT OF COLORED WATER 5-12 WATER QUALITY IMPROVEMENT PROJECTS 5-13 NORTH BASIN GROUNDWATER PROTECTION 5-14 SOUTH BASIN GROUNDWATER PROTECTION 6-1 ARUNDO REMOVAL 6-2 HISTORIC TOTAL DISTRICT WATER DEMANDS 6-3 SCHEMATIC ILLUSTRATION OF IMPACTS OF CHANGING THE AMOUNT OF GROUNDWATER IN STORAGE 6-4 STRATEGIC BASIN OPERATING LEVELS AND OPTIMAL 6-5 BASIN PRODUCTION AND RECHARGE SOURCES 6-6 BASIN PRODUCTION PERCENTAGE HISTORY 6-7 BPP ---PAGE BREAK--- TABLE LIST OF TABLES PAGE GROUNDWATER MANAGEMENT PLAN 2009 UPDATE i 1-1 KEY PERFORMANCE 1-2 SUMMARY OF COMPLETED PROJECTS 2004-2009 2-1 ESTIMATED BASIN GROUNDWATER STORAGE BY HYDROGEOLOGIC 2-2 REPRESENTATIVE ANNUAL BASIN WATER 3-1 DISTRIBUTION OF WELLS IN BASINWIDE MONITORING PROGRAM 3-2 MONITORING OF REGULATED AND UNREGULATED CHEMICALS 3-3 SURFACE WATER QUALITY SAMPLING FREQUENCY WITHIN ORANGE COUNTY......3-15 3-4 GWR SYSTEM PRODUCT WATER QUALITY 3-5 DATA COLLECTION AND REPORTING 4-1 AREA AND STORAGE CAPABILITIES OF RECHARGE 4-2 SOURCES OF RECHARGE WATER 5-1 SECONDARY DRINKING WATER STANDARDS FOR SELECTED CONSTITUENTS 5-2 TDS WATER QUALITY OBJECTIVES FOR LOWER SANTA ANA RIVER BASIN MANAGEMENT ZONES 5-3 SALT INFLOWS FOR ORANGE COUNTY AND IRVINE MANAGEMENT 5-4 SUMMARY OF ECONOMIC BENEFITS OF REDUCED 5-5 NITRATE-NITROGEN WATER QUALITY OBJECTIVE FOR LOWER SANTA ANA RIVER BASIN MANAGEMENT 5-6 SUMMARY OF IMPROVEMENT PROJECTS AND REPLENISHMENT OBLIGATIONS.......5-29 6-1 ESTIMATED POPULATION WITHIN OCWD BOUNDARY 6-2 ESTIMATED FUTURE WATER DEMANDS IN OCWD 6-3 BENEFITS AND DETRIMENTS OF DIFFERENT STORAGE LEVELS 6-4 ACCUMULATED OVERDRAFT, BASIN REFILL, PROBABILITY FACTOR & RAINFALL AMOUNT 6-5 RECHARGE WATER SUPPLIES ESTIMATED FOR 2008-09 6-6 IMPACT OF DROUGHTS ON RECHARGE WATER SUPPLIES 6-7 APPROACHES TO REFILLING THE BASIN 7-1 FY 2008-09 BUDGETED OPERATING EXPENSES 7-2 FY 2008-09 OPERATING 8-1 RECOMMENDATIONS ---PAGE BREAK--- ---PAGE BREAK--- EXECUTIVE SUMMARY EXECUTIVE SUMMARY The Orange County Water District (OCWD) is a special district formed in 1933 by an act of the California Legislature. The District manages the groundwater basin that underlies north and central Orange County. Water produced from the basin is the primary water supply for approximately 2.5 million residents living within the District boundaries. ES-1 Introduction The mission of the OCWD is to provide local water retailers with a reliable, adequate, high quality water supply at the lowest reasonable cost in an environmentally responsible manner. The District implements a comprehensive program to manage the groundwater basin to assure a safe and sustainable supply. The Groundwater Management Plan 2009 Update documents the objectives, operations, and programs aimed at accomplishing the District’s mission. The Orange County groundwater basin meets approximately 60 to 70 percent of the water supply demand within the boundaries of the District as shown in Figures ES-1 and ES-2. Nineteen major producers, including cities, water districts, and private water companies, pump water from the basin and retail it to the public. There are also approximately 200 small wells that pump water from the basin, primarily for irrigation purposes. OCWD History Since its founding, the District has grown in size from 162,676 to 229,000 acres. Along with this growth in area has come a rapid growth in population. Facing the challenge of increasing demand for water has fostered a history of innovation and creativity that has enabled OCWD to increase available groundwater supplies while protecting the long- term sustainability of the basin. Groundwater pumping from the basin has grown from approximately 150,000 acre-feet per year (afy) in the mid-1950s to over 300,000 afy, as shown in Figure ES-3. History of Active Groundwater Recharge To accommodate increasing demand for water supplies, OCWD started actively recharging the groundwater basin over fifty years ago. In 1949, the District began purchasing imported Colorado River water from the Metropolitan Water District of Southern California (Metropolitan), which was delivered to Orange County via the Santa Ana River upstream of Prado Dam. In 1953, OCWD began making improvements in the Santa Ana River bed and constructing off-channel recharge basins to increase recharge capacity. The District currently operates 1,067 acres of recharge facilities adjacent to the Santa Ana River and its main Orange County tributary, Santiago Creek. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-1 ---PAGE BREAK--- EXECUTIVE SUMMARY ES-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Control of Seawater Intrusion and Construction of the Groundwater Replenishment System One of the District’s primary efforts has been the control of seawater intrusion into the groundwater basin, especially in two areas: the Alamitos Gap and the Talbert Gap. OCWD began addressing the Alamitos Gap intrusion by entering a partnership in 1965 with the Los Angeles County Flood Control District to operate injection wells in the Alamitos Gap. Operation of the injection wells forms a hydraulic barrier to seawater intrusion. FIGURE ES- 1 ORANGE COUNTY WATER DISTRICT BOUNDARY ---PAGE BREAK--- EXECUTIVE SUMMARY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-3 To address seawater intrusion in the Talbert Gap, OCWD constructed Water Factory 21, a plant that treated secondary-treated water from the Orange County Sanitation District (OCSD) to produce purified water for injection. Water Factory 21 operated for approximately 30 years until it was taken off line in 2004. It was replaced by an advanced water treatment system, the Groundwater Replenishment (GWR) System. The GWR System, the largest water purification project of its kind, began operating in 2008 to provide water for the Talbert Injection Barrier as well as to supply water to recharge basins in the City of Anaheim. FIGURE ES- 2 ORANGE COUNTY GROUNDWATER BASIN ---PAGE BREAK--- EXECUTIVE SUMMARY FIGURE ES- 3 GROUNDWATER PRODUCTION 0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 1961-62 1966-67 1971-72 1976-77 1981-82 1986-87 1991-92 1996-97 2001-02 2006-07 Water Year: July 1 - June 30 Groundwater Production (acre-feet) Non-Irrigation Irrigation Preparation of the Groundwater Management Plan The District’s previous update to the Groundwater Management Plan was prepared in 2004. The five Key Performance Indicators established in the 2004 plan were accomplished, as shown in Table ES-1. In addition, over eighteen major projects completed between 2004 and 2008 have improved District operations, increased groundwater recharge capacity, and improved water quality. The Groundwater Management Plan 2009 Update provides information on District operations, lists projects completed since publication of the 2004 report, and discusses plans for future projects and operations. The updated plan was prepared and adopted in accordance with procedures stipulated by A.B. 3030 and Section 10750 et seq. of the California Water Code. Goals and Objectives The District’s goals are to protect and enhance groundwater quality, to protect and increase the sustainable yield of the basin in a cost-effective manner and to increase the efficiency of OCWD’s operations. Section 1.8 contains a complete list of management objectives aimed at accomplishing these goals. ES-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- EXECUTIVE SUMMARY TABLE ES- 1 KEY PERFORMANCE INDICATORS 2004 Groundwater Management Plan Key Performance Indicators 2008 Status GWR System began operation in 2008. Reliable, local water supplies available for barrier injection increased from 5 mgd to 30 mgd. Cease landward migration of 250 mg/L chloride contour by 2006 Reversal of landward migration at Talbert Barrier observed in 2008. Increase Prado water conservation pool elevation by four feet by 2005 Memorandum of Agreement with the Army Corps of Engineers was executed in 2006 allowing a four-foot increase in the maximum winter pool elevation. Increase recharge capacity by 10,000 afy Increase in recharge capacity of greater than 10,000 afy occurred with the La Jolla Recharge Basin coming on line in 2008 and operation of Basin Cleaning Vehicles. All water recharged into the basin through District facilities meets or is better than Department of Public Health MCLs and Notification Levels. No exceedances of MCLs or Notification Levels in recharge water as documented in Santa Ana River Water Quality Monitoring Reports (OCWD 2005, 2006, 2007, and 2008) and GWR System permit reports. Reduce basin overdraft by 20,000 afy Basin’s accumulated overdraft was reduced by 202,000 af between June 2004 and June 2007. (OCWD Engineer’s Report, 2008) ES-2 Basin Hydrogeology The Orange County groundwater basin covers an area of approximately 350 square miles underlying the north half of Orange County beneath broad lowlands known as the Tustin and Downey plains. The aquifers comprising the basin extend over 2,000 feet deep and form a complex series of interconnected sand and gravel deposits. In the inland area, generally northeast of Interstate 5, the clay and silt deposits become thinner and more discontinuous, allowing larger quantities of groundwater to flow between shallow and deeper aquifers. Forebay and Pressure Areas The basin is divided into two primary hydrologic divisions; the Forebay and Pressure areas (see Figure ES-2). The boundary between the two areas generally delineates the areas where surface water or shallow groundwater can or cannot move downward to the first producible aquifer in significant quantities from a water supply perspective. Most of the groundwater recharge occurs in the Forebay. OCWD conducts an extensive groundwater monitoring network to collect data to depths of up to 2,000 feet in the basin. Data from these monitoring wells were used to delineate GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-5 ---PAGE BREAK--- EXECUTIVE SUMMARY ES-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE the depth of the “principal” aquifer system, within which most of the groundwater production occurs. Figure ES-4 schematically depicts the basin’s three aquifer systems, with groundwater flowing from Yorba Linda to the coast. FIGURE ES- 4 GROUNDWATER BASIN CROSS-SECTION Shallower aquifers exist above the principal aquifer system. Production from this system, principally for industrial and agricultural uses, is typically about five percent of total basin production. Deeper aquifers exist below the principal aquifer system, but these zones have been found to contain colored water or are too deep to economically construct production wells; few wells penetrate this system. A vast amount of water is stored within the basin, although only a fraction of this amount can be removed without causing physical damage such as seawater intrusion or the potential for land subsidence. Water Budget OCWD developed a hydrologic budget in order to construct a Basin Model and to evaluate basin production capacity and recharge requirements. The hydrologic budget quantifies the amount of basin recharge, groundwater production, and subsurface flows along the coast and across the Orange/Los Angeles County line. Calculation of Groundwater Elevation, Storage, and Accumulated Overdraft Annual changes in the amount of groundwater stored in the basin are estimated using groundwater elevation measurements and aquifer storage coefficients for the three primary aquifer systems in the basin. This three-layer method involves measuring the water levels throughout the basin at the end of each water year at nearly every production and monitoring well in the basin. Water level measurements are contoured and digitized into the Geographic Information System. Storage change volumes for each of the three aquifer levels are determined and then totaled to provide a net annual storage change for the basin. NON-WATERBEARING FORMATION 0 miles 1,000’ 2,000’ 3,000’ Seal Bea Yorba Linda ch Forebay Pres 5 10 15 20 0’ sure Area Ground Surface SHALLOW AQUIFER SYSTEM (Layer 1) PRINCIPAL AQUIFER SYSTEM (Layer 2) DEEP AQUIFER SYSTEM (Layer 3) Seal Beach Pressure Area Forebay Yorba Linda ---PAGE BREAK--- EXECUTIVE SUMMARY The District estimates that the basin can be operated on a short-term basis with a maximum accumulated overdraft (storage reduction from full condition) of approximately 500,000 acre-feet (af) without causing irreversible seawater intrusion and land subsidence. In 2007, OCWD developed a new methodology to calculate accumulated overdraft and storage change. The need for this change was driven by the record- setting wet year of 2004-05, which resulted in the basin approaching a near-full condition. Analysis showed that the traditional method of cumulatively adding the annual storage change each year contained considerable uncertainty. The updated approach is based on a determination of the amount of groundwater in storage in each of the three major aquifer systems. Elevation Trends and Groundwater Model Groundwater level profiles generally following the Santa Ana River in Orange County are prepared to evaluate changes in the basin due to groundwater pumping and OCWD recharge operations. Groundwater levels are managed within a safe basin operating range to protect the long-term sustainability of the basin and to protect against land subsidence. The District has developed a comprehensive computer-based groundwater flow model. Development of the model substantially improved the overall understanding of processes and conditions in the basin. The model also allows analysis of how the basin reacts to various theoretical pumping and recharge conditions. The model’s ability to simulate known and projected future conditions will evolve and improve as new data become available and updated simulations are completed. ES-3 Groundwater Monitoring For its size, the Orange County groundwater basin is one of the world’s most extensively monitored. The comprehensive monitoring program tracks dynamic basin conditions including groundwater production, storage, elevations, and water quality. OCWD’s monitoring program has helped improve groundwater management throughout the basin by: • Establishing on an annual basis the appropriate level of groundwater production. • Determining the extent of seawater intrusion and subsequently building improvements to seawater barriers to prevent and reverse such intrusion. • Discovering areas of groundwater contamination to protect public health and beneficial use of groundwater, and to begin remediation efforts at an early stage. • Assuring that the groundwater basin is managed in accordance with relevant laws and regulations. Collection and Management of Monitoring Data Large-capacity well owners report groundwater production for each of their wells. OCWD operates its own groundwater monitoring network with a diverse cross- section of well types and broad range of well depths and screened intervals. The type GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-7 ---PAGE BREAK--- EXECUTIVE SUMMARY and number of wells in the basin wide monitoring program are shown in Table ES-2; the distribution of wells is shown in Figure ES-5. TABLE ES- 2 DISTRIBUTION OF WELLS IN BASIN WIDE MONITORING PROGRAM Well Type No. of Wells No. of Individual Sample Points Drinking Water Wells 228 228 Industrial And Irrigation wells 123 123 OCWD Monitoring Wells (excluding seawater monitoring) 254 728 OCWD Seawater Intrusion Monitoring Wells 93 244 Total 698 1323 FIGURE ES- 5 PRODUCTION AND MONITORING WELL NETWORK ES-8 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- EXECUTIVE SUMMARY In 2008, nearly 14,000 groundwater samples were collected and analyzed in order to comply with state and federal regulations and to enable OCWD to monitor the water quality of the basin. The number of water quality samples continues to increase in response to new regulatory requirements and to gain a better understanding of the basin. OCWD’s laboratory is state-certified to perform bacteriological, inorganic, and organic analyses. State-certified contractor laboratories analyze radiological samples. OCWD’s water quality monitoring program includes: • Testing groundwater samples for more than 100 regulated and unregulated chemicals at a specified monitoring frequency established by the U.S. Environmental Protection Agency (EPA) and the California Department of Public Health (CDPH) regulations. • Monitoring and preventing the encroachment of seawater into fresh groundwater zones along coastal Orange County. • Assessing Santa Ana River water quality. Since the quality of the surface water that is used to recharge the groundwater basin affects groundwater quality, a routine monitoring program is maintained to continually assess ambient river water quality. Water samples are collected each month from the river. The District also monitors the quality of imported replenishment water and tests selected monitoring wells to assess the water quality in areas where GWR System water is being injected and recharged. Data Management and Publication Data collected in OCWD’s monitoring program are stored in the District’s electronic database, the Water Resources Management System (WRMS). WRMS contains comprehensive well information, as well as information on subsurface geology, groundwater modeling, and water quality. Data are used in calibrating the basin model, evaluating the causes of seasonal groundwater fluctuations, and estimating changes in basin storage throughout the year. Regular District publications include the annual release of the Engineer’s Report on Groundwater Conditions, Water Supply and Basin Utilization; the Santa Ana River Water Quality Monitoring Report; and the Groundwater Replenishment System Operations Annual Report. ES-4 Recharge Water Supply Management OCWD operates recharge facilities to maximize groundwater recharge. Recharging water into the basin through natural and artificial means is essential to support pumping from the basin. The basin’s primary source of water for groundwater recharge is flow from the Santa Ana River. OCWD diverts river flows into recharge basins located in and adjacent to the Santa Ana River and its main Orange County tributary, Santiago Creek. Other sources of recharge water include natural infiltration, recycled water, and imported water. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-9 ---PAGE BREAK--- EXECUTIVE SUMMARY History of Recharge Operations Active recharge of groundwater began in 1949, in response to increasing drawdown of the basin and, consequently, the serious threat of seawater intrusion. In 1953, OCWD began to make improvements in the Santa Ana River bed and areas adjacent to the river to increase recharge capacity. Today the District owns and operates a network of recharge facilities that cover 1,067 acres, as shown in Figure ES-6. The District has an ongoing program to assess enhancements in the existing recharge facilities, evaluate new recharge methods, and analyze potential new recharge facilities. OCWD Recharge Facilities Surface water from the Santa Ana River flows into Orange County through the Prado Dam. The District is able to recharge essentially all non-storm flow in the Santa Ana River that enters Orange County through Prado Dam. The dam was built and is operated by the Army Corps of Engineers (ACOE) for flood control purposes. Agreements between the ACOE and OCWD enable the dam to be operated for water conservation purposes, such that the District is able to capture a portion of the storm flows for groundwater recharge. Water released at Prado Dam naturally flows into Orange County and percolates through the river’s 300-400 foot-wide unlined channel bottom. Active management of recharge begins at the intersection of the river and Imperial Highway in the City of Anaheim. It is in the six-mile reach of the river below Imperial Highway and areas adjacent to the river where many of the recharge basins are located. The recharge facilities are grouped into four major components: the Main River System, the Off-River System, the Deep Basin System, and the Burris Basin/Santiago System. The Main River System consists of approximately 290 acres of the Santa Ana River Channel. One of the District’s main control facilities, the Imperial Inflatable Dam and Bypass structure diverts Santa Ana River water flows from the Main River System into the Off-River System. The Off-River System is a shallow, sandy bottom, 100- to 200- foot wide channel that runs parallel to the Main River System; a levee separates these two systems. Water can be diverted from the Off-River System into the Deep Basin System. These recharge basins range in depth from ten to sixty feet. Flows are regulated between these basins to maximize recharge. Water in the Santa Ana River can also be diverted at the Five Coves Inflatable Dam into the Burris Basin/Santiago System. This system includes 373 acres of shallow and deep recharge basins. The Santiago Pipeline allows water to be diverted from Burris Basin into the Santiago Basins. The Santiago Basins recharge water diverted from Burris Basin as well as flows from Santiago Creek. The creek is a tributary of the Santa Ana River that extends from the Santa Ana Mountains through the City of Orange to its confluence with the Santa Ana River in the City of Santa Ana. ES-10 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- EXECUTIVE SUMMARY FIGURE ES- 6 OCWD RECHARGE FACILITIES IN ANAHEIM AND ORANGE GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-11 ---PAGE BREAK--- EXECUTIVE SUMMARY Sources of Recharge Water Supplies In addition to Santa Ana River and Santiago Creek, other sources of recharge water include natural recharge, imported water, and water purified by OCWD’s GWR System. The GWR System (Figure ES-7) is a cooperative project with the OCSD that began operating in 2008. Secondary-treated wastewater from OCSD undergoes treatment consisting of microfiltration, reverse osmosis, and advanced oxidation with ultraviolet light and hydrogen peroxide. The water purified through the GWR System is injected into the groundwater basin near the coast to maintain a barrier preventing seawater intrusion and provides an additional supply of water for recharge operations. FIGURE ES-7 GROUNDWATER REPLENISHMENT SYSTEM ES-5 Groundwater Quality Management OCWD conducts an extensive program aimed at protecting the quality of the water in the basin. These efforts include groundwater monitoring, participating in and supporting regulatory programs, remediation projects, working with groundwater producers, and providing technical assistance. Groundwater Protection Policy The District adopted a Groundwater Protection Policy in May 1987, in recognition of the serious threat posed by groundwater contamination. This policy is described in Section 5 of the Plan. ES-12 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- EXECUTIVE SUMMARY Salinity and Nitrate Management Managing salinity, the amount of dissolved minerals in water, and nitrates are significant water quality challenges in southern California. Elevated levels of nitrates pose a risk to human health. High concentrations of salts can contaminate groundwater supplies, constrain implementation of water recycling projects, and cause other negative economic impacts such as the need for increased water treatment by residential, industrial and commercial users. Sources of salinity in water used to recharge the groundwater basin include Santa Ana River water, imported water, shallow groundwater within Orange County, seawater migrating into the basin, precipitation, and legacy contamination from historical agricultural operations. Water treatment plants, also referred to as desalters, have been built in Riverside and San Bernardino Counties to reduce salinity levels in water supplies. Within Orange County, desalters in Tustin and Irvine are reducing salinity levels in the groundwater basin. The GWR System provides a dependable supply of low salinity water that is expected to reduce the basin salt imbalance by approximately 47,000 tons/year. Nitrates are one of the most common and widespread contaminants in groundwater supplies. Elevated levels of nitrates in soil and water supplies originate from fertilizer use, animal feedlots and wastewater disposal systems. OCWD conducts an extensive program to protect the basin from nitrate contamination, including operating 450 acres of wetlands in the Prado Basin (Figure ES-8) to naturally remove nitrate before the water enters the District’s recharge facilities. FIGURE ES-8 PRADO WETLANDS GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-13 ---PAGE BREAK--- EXECUTIVE SUMMARY Ninety-eight percent of the drinking water wells pumping from the Orange County groundwater basin meet the nitrate drinking water standard. The two percent that do not meet the nitrate standard are treated to reduce nitrate levels prior to being served to customers. The Irvine and Tustin desalters are in operation to remove salts and nitrate from groundwater. The Irvine Desalter also addresses contamination from organic compounds. Organic Contaminants Ninety-five percent of the basin’s groundwater that is used for drinking water is pumped from the main aquifer. Water from this aquifer continues to be of high quality. OCWD routinely monitors potential contamination and is working to remediate some localized contamination in the shallow aquifer. One contaminant of concern is methyl tertiary butyl ether (MTBE), a chemical previously added to gasoline. The District analyzes groundwater for MTBE and other fuel-related contaminants. The District is implementing remediation efforts to address contamination from volatile organic compounds (VOCs). Two particular projects are the North Basin Groundwater Protection Project and the South Basin Groundwater Protection Project. The North Basin Groundwater Protection Project is being constructed in Anaheim and Fullerton to remove and contain groundwater contaminated with VOCs. The South Basin Groundwater Protection Project is being designed to address VOC and perchlorate contamination in the area of southeast Santa Ana/South Tustin and the western portion of Irvine. ES-6 Integrated Management of Production and Recharge OCWD is internationally known for its unique, proactive, supply-side management approach. This is a major factor that has enabled the District to develop one of the most advanced and progressive groundwater management systems in the world. Growth in demand for water supplies has challenged the District to augment recharge water supplies, effectively manage demands on the basin, and balance the amount of total recharge and total pumping to protect the basin. Cooperative Efforts to Protect Water Supplies and Water Quality OCWD participates in cooperative efforts with local, state, and federal regulatory agencies and stakeholders within the District boundaries and in the Santa Ana River Watershed. For example, the ACOE works cooperatively with OCWD to store water behind Prado Dam and to release flows at rates that allow for the maximum capture of water for recharge operations. Other cooperative efforts include natural resource conservation efforts in the Prado Basin and participating in working groups and task forces with stakeholders throughout the watershed. Water Supplies OCWD provides access to basin supplies at a uniform cost to all entities without regard to the length of time they have been producing from the basin. The District’s programs include operating the groundwater recharge basins, increasing supplies of recycled ES-14 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- EXECUTIVE SUMMARY water available for groundwater recharge, producing recycled water for irrigation and other non-potable uses, participating in water conservation efforts, and working with the Municipal Water District of Orange County (MWDOC) in developing and conducting other supply augmentation projects and strategies. Water Demand Numerous factors influence water demands such as population growth, economic conditions, conservation programs, and hydrologic conditions. Estimates of future demands are therefore subject to some uncertainty and are updated on a regular basis. Total water demand within the District’s boundary for water year 2007-08 (July 1- June 30) was 480,000 af. Total demand is met with a combination of groundwater, imported potable water, local surface water, and recycled water used for irrigation and industrial purposes. Figure ES-9 shows historical total District water demands from 1984 to the present. Estimating water demands is necessary for the planning of future water supply project and programs. FIGURE ES-9 HISTORICAL TOTAL DISTRICT WATER DEMANDS 0 100,000 200,000 300,000 400,000 500,000 600,000 1984-85 1985-86 1986-87 1987-88 1988-89 1989-90 1990-91 1991-92 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 Water Year AFY Basin Operating Range Total pumping from the basin is managed through a process that uses financial incentives to encourage groundwater producers to pump an aggregate amount of water that is sustainable without harming the basin. The process that determines a sustainable level of pumping considers the basin’s safe operating range and the amount of recharge water available to the District. The basin operating range refers to the upper and lower levels of groundwater storage in the basin that can be reached without GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-15 ---PAGE BREAK--- EXECUTIVE SUMMARY causing negative impacts. Each year the District estimates the level of storage for the following year. Integrated Management of Recharge and Production Over the long term, the basin must be maintained in an approximate balance to ensure the long term viability of the water supply. In one particular year, water withdrawals may exceed water recharged as long as over the course of a number of years this is balanced by years where water recharged exceeds withdrawals. Levels of basin production and water recharged since water year 1991-92 are shown in Figure ES-10. The primary mechanism used by OCWD to manage pumping is the Basin Production Percentage (BPP). The BPP is the percentage of each Producer’s total water supply that comes from groundwater pumped from the basin. The BPP is set uniformly for all Producers. Groundwater production at or below the BPP is assessed the Replenishment Assessment. Pumping above the BPP is also assessed a Basin Equity Assessment, which is calculated so that the cost of groundwater production is higher than purchasing imported potable water. This serves to discourage production above the BPP. FIGURE ES-10 BASIN PRODUCTION AND RECHARGE SOURCES - 100,000 200,000 300,000 400,000 500,000 600,000 91-92 92-93 93-94 94-95 95-96 96-97 97-98 98-99 99-00 00-01 01-02 02-03 03-04 04-05 05-06 06-07 07-08 Water Year AFY SAR Baseflow Natural Incidental Recharge Captured SAR Stormflow Imported Water/GWR System Groundwater Production ES-16 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- EXECUTIVE SUMMARY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ES-17 Drought Management During a drought, flexibility to maintain pumping from the basin becomes increasingly important. To the extent that the basin has water in storage that can be pumped out during a drought, the basin provides a valuable water supply asset during drought conditions. For the basin to serve as a safe, reliable supply, sufficient groundwater must be stored before a drought occurs and the basin needs to be refilled after a period of storage reduction occurs. ES-7 Financial Management The District has an excellent revenue base and a strong “AA+” financial rating. The District also has the ability to issue additional long-term debt, if necessary, to develop projects to increase the basin’s yield and protect water quality. The annual operating budget for fiscal year 2008-09 was approximately $116.3 million. OCWD maintains reserve funds to ensure financial integrity and to purchase supplemental water when it becomes available for groundwater recharge. The District’s primary sources of revenue include the Replenishment Assessment, Basin Equity Assessment, property taxes, and other miscellaneous revenues such as rental fees on District property. The District’s programs to protect and increase the basin’s sustainable yield in a cost- effective manner continue to evolve due to changes in the availability of recharge water supplies. Below average rainfall over the past four years in the Santa Ana River Watershed as well as other factors has reduced the availability of Santa Ana River water. The availability of imported water supplies for groundwater recharge has also changed significantly in the last few years. The occurrence of wet and dry periods, the future availability and cost of imported water supplies for recharge, and changing water management practices of agencies in the watershed will continue to affect the District’s management of the basin. ---PAGE BREAK--- EXECUTIVE SUMMARY This page left blank intentionally ES-18 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 1 INTRODUCTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-1 1 INTRODUCTION 1.1 History of OCWD The OCWD was formed by a special act of the California Legislature in 1933 to manage the groundwater basin that underlies north and central Orange County. District boundaries are shown in Figure 1-1. OCWD is not a water retailer and does not serve water to the public; rather, the District manages the groundwater basin. Figure 1-1 Orange County Water District Boundary Nineteen major producers, including cities, water districts, and private water companies, pump water from the basin and retail it to the public. There are also approximately 200 small wells that pump water from the basin, primarily for irrigation purposes. OCWD protects and manages the quantity and quality of the groundwater resource that meets approximately 60 to 70 percent of the water supply demand for a population of over 2.5 million. Since its founding, the District has grown in area from 162,676 to 229,000 acres and has experienced an increase in population from approximately The Orange County Water District (OCWD) manages the Orange County Groundwater Basin (the basin) in coastal Southern California This section provides background information on the District and sets the framework for the Groundwater Management Plan 2009 Update (Plan). The subsections below: • Discuss the District’s formation, mission, and operating authorities. • Trace changing conditions in the basin that are important to development of the Plan. • Describe the public participation component of the Plan. • Discuss the Plan’s compliance with the California Water Code. • Present basin management objectives that guide the District’s management of the basin. • Explain the District’s public education programs. ---PAGE BREAK--- SECTION 1 INTRODUCTION 1-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 120,000 to 2.5 million people. Facing the challenge of increasing demand for water has fostered a history of innovation and creativity that has enabled OCWD to increase available groundwater supplies while protecting the long-term sustainability of the basin. The District’s powers, as defined in its enabling legislation by the State of California (Water Code App §40-1, et seq., or the ‘OCWD Act’), include the following: Within or outside the District to construct, purchase, lease or otherwise acquire, and to operate and maintain necessary waterworks… to replenish the undergroundwater basin within the district, or to augment and protect the quality of the common water supplies of the district, … (portions of Section 2.5 of OCWD Act) For the common benefit of the district and for the purpose of managing the groundwater basin and managing, replenishing, regulating, and protecting the groundwater supplies within the district to exercise the following powers: Provide for the conjunctive use of groundwater and surface water resources within the district area. Store water in undergroundwater basins or reservoirs within or outside of the district. Regulate and control the storage of water and the use of groundwater basin storage space in the groundwater basin. Purchase and import water into the district. Transport, reclaim, purify, treat, inject, extract, or otherwise manage and control water for the beneficial use of persons or property within the district and to improve and protect the quality of the groundwater supplies within the district. (Portions of Section 2.6 of OCWD Act) To provide for the protection and enhancement of the environment within and outside the district in connection with the water activities of the district. (Section 2.7 of OCWD Act) These powers illustrate the range of activities the District is involved with in managing the groundwater basin. The Orange County Groundwater Basin was used by early settlers to supplement Santa Ana River surface water. Adequate, dependable water supplies were always a challenge for the residents of this semi-arid land. By 1900, conflicts over water supplies were escalating. The county’s economic growth into an agricultural center was only one source of the problem. The other source was upstream: Santa Ana River flows were decreasing due to increased water use in the basins upstream of Orange County. San ---PAGE BREAK--- SECTION 1 INTRODUCTION Bernardino, Riverside, and Orange Counties were dependent on the same water source – the Santa Ana River in the Santa Ana River Watershed (shown in Figure 1-2). FIGURE 1-2 SANTA ANA RIVER WATERSHED GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-3 ---PAGE BREAK--- SECTION 1 INTRODUCTION In the early 1900s, reduced river flows and lowering of the Orange County groundwater table heightened conflicts between water users. Lower basin users initiated legal and other efforts to secure rights to water supplies. In 1932, The Irvine Company filed suit against upper basin users to protect its rights to river flows. Around the same time, the Orange County Farm Bureau formed the Santa Ana Basin Water Rights Protective Association to consider options to secure adequate supplies. This group developed a series of proposals, one of which led to legislation that created the OCWD. The Orange County Water District Act was passed by the state legislature on June 4, 1933. The new District joined The Irvine Company’s lawsuit and was party to the 1942 settlement of that suit. The agreement limited the amount of river water that could be used for recharge in the upper basin to ensure that Orange County would have a share of Santa Ana River water. Creation of the District and settlement of the lawsuit did not immediately solve the water supply problems in Orange County. Throughout the 1930s to early 1950s, groundwater pumping continued to exceed the rate of water recharged into the basin, a condition referred to as “overdraft.” OCWD began looking for additional water supplies. Efforts to bring more water into southern California were already underway. The Metropolitan Water District of Southern California (Metropolitan), created in 1927, built an aqueduct to transport and sell Colorado River water. Between 1949 and 1953, OCWD purchased 28,000 acre feet per year (afy) of Metropolitan water for groundwater recharge. However, these additional supplies were not enough to satisfy growing demand; by 1954, groundwater levels fell an average of fifteen feet below sea level. Now, the principal limitation faced by OCWD was the lack of an adequate, dependable funding base for purchasing the large amounts of recharge water needed to refill the overdrafted basin. OCWD’s only funding source at that time was local ad valorem taxes. Using property taxes to buy imported water was becoming controversial. Property owners in most of the District belonged to Metropolitan so their property taxes were funding imported water purchases. But water users pumping from the basin who were not Metropolitan members were benefiting from the imported supply without paying for it. In addition, some tax-paying property owners were not using the water that they were being charged for. A twelve-person Orange County Water Basin Conservation Committee (the Committee of Twelve) was formed in 1952 to develop a solution to the funding problem. This process is described by author William Blomquist in his book “Dividing the Waters” (Blomquist, 1992). “The area’s water management problems were discussed at a joint meeting in 1952 of the Water Problems Committee of the Orange County Farm Bureau, the Water Committee of the Associated Chambers of Commerce, and the Board of Directors of the Orange County Water District. The twelve-man Orange County Water Basin Conservation Committee (the Committee of 12) was formed to study the issues further and develop recommendations. The Committee of 12 maintained the area’s basic commitment to increasing supply rather than restricting 1-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 1 INTRODUCTION demand. They considered and rejected centralized control over water consumption and distribution by an agency empowered to enforce conservation, or adjudication and limitation of water rights using the court- reference procedure. They supported instead a proposal to fund replenishment by taxing pumping. This approach held the promise of raising the necessary funds, relating producers’ taxation to their benefits received, and relieving non-producers from paying for replenishment except to the extent that they purchased water from producers. Furthermore, at least theoretically, a tax on pumping would build in conservation incentives without mandating conservation. OCWD was not authorized to tax pumping, so the Orange County Water District Act would have to be amended. The Committee of 12 assembled a package of amendments that amounted to a substantial redesign of the district. To be fair, a pump tax would have to be implemented basin-wide, so the Committee proposed enlarging the district’s territory to include Anaheim, Fullerton, and Santa Ana, plus areas owned by the Anaheim Union Water Company and the Santa Ana Valley Irrigation Company near the canyon. A pump tax would make it necessary to measure and record water production from the thousands of wells within the district, so an amendment was proposed requiring every producer therein to register wells with OCWD and to record and submit production data to the District twice per year. The Committee also proposed that an annual District Engineer’s Report on basin conditions and groundwater production be submitted to the District and water users, to allow them to monitor the effects of the replenishment program and to provide a shared picture on a regular basis of basin conditions, including the extent of seawater intrusion and the level of the water table.” Passage of these proposed amendments in 1954 was one of the most significant modifications to the original District Act. These major revisions gave OCWD the authority to assess a charge to pump groundwater, known as a Replenishment Assessment (RA). The OCWD Board of Directors voted to institute the first RA on June 9, 1954. The District now had adequate funds to purchase the amount of imported water needed for groundwater recharge, to monitor water quality and basin conditions, maintain and improve spreading facilities and pay for administrative costs. One pressing problem arising from overdrafting the basin was seawater intrusion. In 1956, the groundwater level dropped to its lowest historical point, as much as 40 feet below sea level, and seawater intruded 3 ½ miles inland. Although imported water was helping refill the basin, the challenge of seawater intrusion remained. This was a problem primarily in two areas: the Alamitos Gap at the mouth of the San Gabriel River at the Orange County/Los Angeles County border and the Talbert Gap in Fountain Valley. In 1965, the District began a joint program that continues to the present with the Los Angeles County Flood Control District to inject fresh water in the Alamitos Gap to prevent saltwater intrusion. The Talbert Gap was a greater challenge as it needed nearly six times the amount of water. After much research and planning, the District built Water Factory 21 (WF-21), a GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-5 ---PAGE BREAK--- SECTION 1 INTRODUCTION water treatment plant that treated secondary-treated water from the Orange County Sanitation District (OCSD) to produce purified water for injection into the Talbert Gap. For over 20 years, a blend of WF-21 water and imported water was used to successfully manage seawater intrusion at the Talbert Gap. WF-21, with a capacity that varied through time from four to fifteen million gallons per day (mgd), operated until 2004 when it was shut down to allow for construction of the Groundwater Replenishment (GWR) System. In operation since 2008, the GWR System is capable of producing up to 72 mgd of water for use in Talbert Barrier operations and for groundwater recharge. OCWD’s recharge operations have played a central role in expanding water supplies. Efforts to increase the capture of Santa Ana River baseflows and stormflows and to recharge imported water date back to 1949. Currently, OCWD operates approximately 1,067 acres of riverbed and off-stream infiltration basins in the cities of Anaheim and Orange. Figure 1-3 is a view of the Santa Ana River looking upstream. Freeway 22 crosses the river in the foreground, Freeway 5 in the middle of the photograph, and Freeway 57 in the background. FIGURE 1-3 SANTA ANA RIVER LOOKING UPSTREAM IN ANAHEIM AND ORANGE OCWD has achieved world-renowned status for its innovative approach to groundwater recharge, water quality protection, and groundwater resource management. The District has employed groundwater management techniques to increase the annual yield from the basin as shown in Figure 1-4. Annual production increased from approximately 150,000 afy in the mid-1950s to approximately 350,000 afy in water year 2007-08. 1-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 1 INTRODUCTION OCWD has managed the basin in order to provide a reliable supply of relatively low-cost water and to accommodate rapid population growth while at the same time avoiding the costly and time-consuming adjudication of water rights experienced in nearly every other major groundwater basin in Southern California. FIGURE 1-4 GROUNDWATER PRODUCTION 1961-2008 0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 1961-62 1966-67 1971-72 1976-77 1981-82 1986-87 1991-92 1996-97 2001-02 2006-07 Water Year: July 1 - June 30 Groundwater Production (acre-feet) Non-Irrigation Irrigation Note: Non-irrigation includes In-lieu recharge. (See explanation of In-lieu recharge water in Section 4.2.4.3) 1.2 Groundwater Producers The local agencies that produce the majority of the groundwater from the basin are shown in Figure 1-5. As part of its plan to involve other affected agencies and work cooperatively where service areas or boundaries overlie the basin, the District meets with nineteen local, major water producers to discuss and evaluate important basin management issues. This group is referred to as the groundwater producers (Producers). Generally each year a chairman is elected to represent the group. This meeting provides a forum for the Producers to provide their input to the District on important issues such as: • Setting the Basin Production Percentage (BPP) each year; • Reviewing the merits of proposed capital improvement projects; • Purchasing imported replenishment water to recharge the groundwater basin; • Reviewing water quality data and regulations; GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-7 ---PAGE BREAK--- SECTION 1 INTRODUCTION • Maintaining and monitoring basin water quality; and • Budgeting and considering other important policy decisions. The District as the groundwater basin manager and the Producers as the local retailers cooperate to serve the 2.5 million residents within the OCWD service territory. The Producers and OCWD served as the Advisory Committee for the preparation of this Groundwater Management Plan. FIGURE 1-5 RETAIL WATER AGENCIES WITHIN OCWD 1-8 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 1 INTRODUCTION 1.3 Public Education Programs Proactive community outreach and public education are central to the operation of the OCWD. Each year, staff members give more than 120 presentations to community leaders and citizens, conduct more than 70 tours of OCWD facilities, and take an active part in community events. In addition to presentations and tours, OCWD administers multiple education programs as described below. Since its inception in 1996, the Children’s Water Education Festival has been the largest of its kind in the nation, hosting more than 6,000 children each year. This two- day outdoor event teaches children about water resources, recycling, pollution prevention, wetland preservation, and other environmental topics through interactive and hands-on activities. In 2007, the O.C. Water Hero program was initiated to make water conservation fun while helping children and parents develop effective water-use efficiency habits that will last a lifetime. The program challenges both children and their parents to commit to saving 20 gallons of water a day. O.C. Water 101 is a free water education class that is offered to the public. This one- day session focuses on the global water crisis, how water affects health, California’s unique water situation, future challenges for water supplies in Orange County, and how water agencies are helping to conserve available water resources. Discussions include high-tech solutions to help alleviate water shortages today and in the future, as well as providing individuals with the resources and information necessary to save water. The Hotel/Motel Water Conservation Program began in 1999 to assist hotels and motels in Orange County. At no cost, hotels and motels can order laminated towel rack hangers, bed cards, or combination cards that ask guests to consider reusing their towels and bed linens during their stay. The cards, which gently encourage guests to be environmentally aware, help hotels and motels save money and water. In 2008, the District, in conjunction with the Municipal Water District of Orange County (MWDOC) and the Orange County Business Council, hosted the O.C. Water Summit, which brought over 400 key policy makers, community leaders and business professionals together to discuss the state’s water challenges and possible regional solutions. The District was recognized as a Groundwater Guardian member in 1996, thereafter forming the OCWD Groundwater Guardian Team. This program is designed to empower local citizens and communities to take voluntary steps toward protecting groundwater resources. The OCWD Groundwater Guardian Team attends and supports community events that are related to this cause. Through its programs and outreach efforts OCWD informs and educates the public about Orange County’s water supply, as well as overall water issues. OCWD strives to draw the communities’ attention to the state’s water needs and teaches them effective ways to minimize water consumption. The community is encouraged to make life-long commitments to conserving water and respecting it as a precious resource. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-9 ---PAGE BREAK--- SECTION 1 INTRODUCTION 1.4 Preparation of the Orange County Water District Groundwater Management Plan OCWD prepared the first Groundwater Management Plan in 1989 and updated the plan in 1990, 1994, and 2004. The 2009 update of the Plan includes new information about projects completed by the District in the past five years and the updated approach to calculating basin storage changes. The Plan identifies OCWD’s goals and basin management objectives in protecting and managing the Orange County groundwater basin. The Plan also describes factors for the District’s Board to consider in making decisions regarding how much pumping the basin can sustain. Specific projects that may be developed as a result of recommendations in the Plan would be separately reviewed and approved by the District’s Board of Directors and processed for environmental review prior to project implementation. The Plan does not commit the District to a particular program or level of basin production, but describes the factors to consider and key issues as the Board makes basin management decisions on a regular basis each year. Potential projects that are conceptually described in the Plan are described in greater detail in the District’s Long-Term Facilities Plan (OCWD, 2009). 1.5 OCWD Accomplishments, 2004-2008 In the OCWD 2004 Groundwater Management Plan, the District established quantifiable objectives, identified as Key Performance Indicators. Those Key Performance Indicators are listed in Table 1-1 along with a summary of actions taken and projects completed to accomplish them. TABLE 1-1 KEY PERFORMANCE INDICATORS 2004 Groundwater Management Plan Key Performance Indicators 2008 Status GWR System began operation in 2008. Reliable, local water supplies available for barrier injection increased from 5 mgd to 30 mgd. Cease landward migration of 250 mg/L chloride contour by 2006 Reversal of landward migration at Talbert Barrier observed in 2008. Increase Prado water conservation pool elevation by four feet by 2005 Memorandum of Agreement with the Army Corps of Engineers was executed in 2006 allowing a 5,000 af increase in the maximum winter pool elevation. Increase recharge capacity by 10,000 afy Increase in recharge capacity of greater than 10,000 afy occurred with the La Jolla Recharge Basin coming on line in 2008 and operation of Basin Cleaning Vehicles. 1-10 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 1 INTRODUCTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-11 2004 Groundwater Management Plan Key Performance Indicators 2008 Status All water recharged into the basin through District facilities meets or is better than Department of Public Health MCLs and Notification Levels No exceedances of MCLs or Notification Levels in recharge water as documented in Santa Ana River Water Quality Monitoring Reports (OCWD 2005, 2006, 2007, 2008) and GWR System permit reports. Reduce basin overdraft by 20,000 afy Basin’s accumulated overdraft was reduced by 202,000 af between June 2004 and June 2007. (OCWD Engineer’s Report, 2008) Major accomplishments since adoption of the 2004 Plan include: • Phase 1 of the GWR System began operating in 2008 with a capacity of purifying 72 afy of water for the Talbert Barrier and groundwater recharge. • The Irvine Desalter Project, a cooperative project between OCWD and Irvine Ranch Water District (IRWD), began operating in 2007 to remediate groundwater contamination and provide 8,000 afy of additional water supplies. • The Report on Evaluation of Orange County Groundwater Basin Storage and Operational Strategy, published in February 2007, established a new methodology for calculating accumulated overdraft and establishing new full-basin benchmarks (see Appendix • Development of a groundwater model. • Beginning the construction of the North Basin Groundwater Protection Project. • Securing the rights to divert and use up to 362,000 afy of Santa Ana River water through a decision of the State Water Resources Control Board in December 2008. A comprehensive list of projects completed between 2004 and 2009 and the location in the Plan of the project description is shown in Table 1-2. ---PAGE BREAK--- SECTION 1 INTRODUCTION Table 1-2 Summary of Completed Projects 2004-2009 Project Description Location in GWMP Construction Completed Operation Began Groundwater Replenishment System Purifies up to 72,000 afy of secondary-treated water from OCSD to create a new water supply for seawater intrusion barrier and groundwater recharge Section 4.2.3.1 2007 2008 Prado Basin Water Conservation Project Increases winter-time storage level at Prado Dam by 5,000 af Section 4.1.1 N/A 2006 Talbert Barrier Expansion Expanded Talbert Seawater Intrusion Barrier by constructing 8 new injection wells (4 with 1 casing each and 4 with 3 casings each) Section 6.3.3 2007 2008 Irvine Desalter Project Constructed extraction and treatment system to pump and treat up to 8,000 afy contaminated groundwater Section 5.8.4 2007 2007 La Jolla Recharge Basin New 6-acre recharge basin increases recharge capacity up to 9,000 afy Section 4.4.1 2008 2008 Olive Basin Intake Structure Improvements Construction of new intake structure and transfer pipe decreases sediment fouling of recharge basin Section 4.4.1 2006 2007 Basin Cleaning Vehicles Construction of four basin cleaning vehicles removes sediment from recharge basins Section 4.1 2004 2004 Santiago Creek Recharge Enhancement Grading of Santiago Creek bed improves recharge rate by an estimated 3,600 afy Section 4.4.1 2008 2008 Conjunctive Use “8 Well Project” Construction of 8 new extraction wells as part of Conjunctive Use Project with MWD to allow storage and withdrawal of imported water in the groundwater basin for use in drought years Section 6.3.3 2007 N/A 1-12 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 1 INTRODUCTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-13 Project Description Location in GWMP Construction Completed Operation Began Mini-Anaheim Recharge Basin Modifications Modifications to increase recharge basin performance Section 4.4.1 2005 2005 Kraemer-Miller Pipeline Improvements New pipelines to provide enhanced supply of recharge water to recharge basins Section 4.4.1 2007 2007 Santiago Creek Monitoring Wells Three new monitoring wells constructed to assess hydrogeologic conditions along Santiago Creek Section 4.2.2 2009 2009 Monitoring Wells for GWR System Construction of three new monitoring wells for GWR System compliance monitoring Section 3.7.3 2004 2005 Monitoring Wells for North Basin Groundwater Protection Project Construction of new monitoring wells to assess occurrence of groundwater contamination Section 5.8.1 2008 2008 Extraction Wells for North Basin Groundwater Protection Project Four new extraction wells constructed to remove contaminated groundwater Section 5.8.1 2009 Estimated in 2010 Lincoln & Burris Exploratory Wells Construction of ten monitoring wells to characterize the ability of sediments adjacent to the basin to percolate water Section 4.4.1 2006 2007 Prado Wetlands Reconstruction Flood damage repairs restore wetlands function Section 5.3.3 2008 2008 Warner Basin Dam Construction of a dam to replace need for building temporary earthen berms for each basin cleaning. Section 4.4.1 2007 2007 ---PAGE BREAK--- SECTION 1 INTRODUCTION 1.6 Public Outreach The California Water Code describes the process for development and adoption of a groundwater management plan that includes a public participation component. To adopt this plan, publicly-noticed meetings held as part of the District’s regularly-scheduled board meetings and information were posted on the OCWD website. Appendix A contains copies of the public notices. In addition to the publicly-noticed public participation opportunities and postings on the web site, the District held workshops with the Producers. The Producers include cities, special districts, and investor-owned utilities that produce more than 90 percent of the water pumped from the basin. The content of the Plan was developed with input and review from the Producers through holding workshops and providing the Producers with draft versions of the Plan prior to its finalization. This group and OCWD served as the advisory committee of stakeholders guiding the development and implementation of the plan and providing a forum for resolving controversial issues. As part of its overall outreach program, the District informs and engages the public in groundwater discussions through an active speaker’s bureau, media releases, and the water education class “Orange County Water 101”. 1.7 Compliance with California Water Code Criteria regarding adoption of a groundwater management plan are included in Section 10750 et seq. of the California Water Code, also referred to as A.B. 3030. A complete list of required and recommended components of groundwater management plans and the location of those components in the Plan can be found in Appendix B. This plan is developed to meet the requirements of the California Water Code. 1.8 Groundwater Management Goals and Basin Management Objectives OCWD’s goals in managing the Orange County groundwater basin are as follows: • To protect and enhance the groundwater quality of the Orange County groundwater basin, • To protect and increase the sustainable yield of the basin in a cost- effective manner, and • To increase the efficiency of OCWD’s operations. Basin management objectives that accomplish all three of the above mentioned goals include: • Updating the Groundwater Management Plan periodically, • Updating the Long-Term Facilities Plan periodically, and • Continuing annual publication of the Santa Ana River Water Quality Report; the Engineer’s Report on the Groundwater Conditions, Water Supply and Basin 1-14 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 1 INTRODUCTION Utilization; the Santa Ana River Watermaster Report; and the Groundwater Replenishment System Operations Annual Report. More specific basin management objectives set to accomplish one of the above mentioned goals are summarized below and described in detail in this report. 1.8.1 PROTECT AND ENHANCE GROUNDWATER QUALITY Basin management objectives established by OCWD to protect and enhance groundwater quality include: • Conducting groundwater quality monitoring programs throughout the basin. • Monitoring and managing recharge water supplies so that water recharged through District facilities meets or is better than primary drinking water levels and notification levels. • Monitoring the quality of Santa Ana River water on a routine basis at Imperial Highway and in the upper watershed. • Implementing the District’s Groundwater Quality Protection Policy. • Constructing and managing water quality treatment projects. • Operating seawater intrusion barriers to prevent landward migration of seawater into the groundwater basin. • Supporting natural resource programs in the Santa Ana River Watershed to improve water quality. • Participating in cooperative efforts with regulators and stakeholders within the Santa Ana River Watershed. 1.8.2 PROTECT AND INCREASE THE BASIN’S SUSTAINABLE YIELD IN A COST EFFECTIVE MANNER Basin management objectives established by OCWD to protect and increase the basin’s sustainable yield include: • Monitoring groundwater levels, recharge rates, and production rates. • Operating the groundwater basin in accordance with the Groundwater Basin Storage and Operational Strategy. • Managing recharge operations to maximize recharge of the groundwater basin. • Researching and implementing new strategies and programs to increase recharge capacity. • Promoting incidental recharge to the extent feasible without negatively impacting groundwater quality. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 1-15 ---PAGE BREAK--- SECTION 1 INTRODUCTION 1-16 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE • Planning for and conducting programs that maximize the capacity of the basin to respond to and recover from droughts. • Supporting natural resource programs in the Santa Ana River watershed. 1.8.3 Increase Operational Efficiency Basin management objectives established by OCWD to increase operational efficiency include: • Managing the District’s finances to provide long-term fiscal stability and to maintain financial resources to implement District programs. • Operating District programs in a cost-effective and efficient manner. • Managing natural resource programs in the Santa Ana River watershed in an efficient manner. • Implementing efficient environmental management programs to reduce greenhouse gas emissions, such as use of solar power where feasible. District programs that are conducted to meet the state goals and basin management objectives and to contribute to a more reliable supply for long-term beneficial uses of groundwater are described in the following sections, a summary of which can be found in Appendix C. ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY 2 BASIN HYDROGEOLOGY • Explains the updated methodology for calculating accumulated overdraft and groundwater storage change implemented in 2007. • Traces the history, development, and operation of the District’s Basin Model. • Describes the major components of inflows and outflows that compromise the basin water budget. • Presents groundwater storage and elevation trends and issues related to land subsidence. The groundwater basin covers approximately 350 square miles in north-central Orange County and is composed of layers of sediment with variable thickness and hydraulic properties. Because of the basin’s size and complexity, understanding basin hydrogeology is critical to successful water management. This section: • Describes the hydrogeologic characteristics of the basin, including aquifer systems, basin boundaries, and physiographic features. 2.1 DESCRIPTION OF BASIN HYDROGEOLOGY The Orange County Groundwater Basin is located in the area designated by the California Department of Water Resources (DWR) as Basin 8-1, the “Coastal Plain of Orange County Groundwater Basin” in Bulletin 118 (DWR, 2003). Figure 2-1 displays the OCWD boundaries in relation to the boundaries of Basin 8-1. The groundwater basin underlies the north half of Orange County beneath broad lowlands known as the Tustin and Downey plains. The basin covers an area of approximately 350 square miles, bordered by the Coyote and Chino Hills to the north, the Santa Ana Mountains to the northeast, and the Pacific Ocean to the southwest. The basin boundary extends to the Orange County-Los Angeles line to the northwest, where groundwater flow is unrestricted across the county line into the Central Basin of Los Angeles County (see Figure 2-2). The Newport-Inglewood fault zone forms the southwestern boundary of all but the shallow aquifer in the basin. Basin aquifers are over 2,000 feet deep and form a complex series of interconnected sand and gravel deposits (DWR, 1967). In coastal and central portions of the basin, these deposits are extensively separated by lower-permeability clay and silt deposits, known as aquitards. In the inland area, generally northeast of Interstate 5, the clay and silt deposits become thinner and more discontinuous, allowing larger quantities of groundwater to flow more easily between shallow and deeper aquifers. Figure 2-3 presents a geologic cross section through the basin along the Santa Ana River. Shallower aquifers exist above the principal aquifer system, the most prolific being known as the Talbert aquifer. Production from this shallow aquifer system is typically about five percent of total basin production. The majority of water from the shallow GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-1 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY aquifer is pumped by small systems for industrial and agricultural use although the cities of Garden Grove, Anaheim, and Tustin have a few large system wells that pump from the shallow aquifer for municipal use. Deeper aquifers exist below the principal aquifer system. Few wells penetrate into this region because of the high cost of drilling deep wells and because the aquifers contain colored water in some areas. The treatment and use of colored water is discussed in detail in Section 5.4. FIGURE 2-1 DWR Bulletin 118 Groundwater Basins 2-2 GROUNDWATER MANAGEMENT PLAN 2009 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-3 2.1.1 FOREBAY AND PRESSURE AREAS The Department of Water Resources, formerly the Division of Water Resources (DWR, 1934), divided the basin into two primary hydrologic divisions, the Forebay and Pressure areas, as shown in Figure 2-2. The Forebay/Pressure area boundary generally delineates the areas where surface water or shallow groundwater can or cannot move downward to the first producible aquifer in quantities significant from a water-supply perspective. From a water-quality perspective, the amount of vertical flow to deeper aquifers from surface water or shallow groundwater may be significant in terms of impacts of past agricultural or industrial land uses fertilizer application and leaky underground storage tanks). FIGURE 2-2 ORANGE COUNTY GROUNDWATER BASIN ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-3 GEOLOGIC CROSS-SECTION THROUGH ORANGE COUNTY GROUNDWATER BASIN 2-4 GROUNDWATER MANAGEMENT PLAN ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY The Forebay refers to the area of intake or recharge where most of the groundwater recharge occurs. Highly-permeable sands and gravels with few and discontinuous clay and silt deposits allow direct percolation of Santa Ana River and other surface water. The Forebay area encompasses most of the cities of Anaheim, Fullerton, and Villa Park and portions of the cities of Orange and Yorba Linda. The Pressure Area, in a general sense, is defined as the area of the basin where large quantities of surface water and near-surface groundwater is impeded from percolating into the major producible aquifers by clay and silt layers at shallow depths (upper 50 feet). The principal and deeper aquifers in this area are under “confined” conditions (under hydrostatic pressure); the water levels of wells penetrating these aquifers exhibit large seasonal variations. Most of the central and coastal portions of the basin fall within the Pressure Area. 2.1.2 GROUNDWATER SUBBASINS, MESAS AND GAPS The Irvine subbasin, bounded by the Santa Ana Mountains and the San Joaquin Hills, forms the southern-most portion of the basin. The Costa Mesa Freeway (State Route 55) and Newport Boulevard form the subbasin’s approximate western boundary with the main basin. Here the aquifers are thinner and contain more clay and silt deposits than aquifers in the main portion of the basin. The Irvine Ranch Water District (IRWD) is the primary groundwater producer. The aquifer base in the Irvine subbasin ranges from approximately 1,000 feet deep beneath the former Marine Corps Air Station (MCAS) Tustin to less than 200 feet deep at the eastern boundary of the former MCAS El Toro. East of former MCAS El Toro, the aquifer further thins and transitions into lower-permeability sandstones and other semi- consolidated sediments, which have minor water storage and transmission capacity. Groundwater historically flowed out of the Irvine subbasin westerly into the main basin since the amount of natural recharge in the area, predominantly from the Santa Ana Mountains, was typically greater than the amount of pumping (Singer, 1973; Banks, 1984). With the operation of the Irvine Desalter Project commencing in 2007, groundwater production in the Irvine subbasin may exceed the natural replenishment from the adjacent hills and mountains, in which case groundwater would be drawn into the Irvine subbasin from the Main Basin. The Yorba Linda subbasin is located north of the Anaheim Forebay recharge area, within the cities of Yorba Linda and Placentia. Due to low transmissivity and high total dissolved solids (TDS) concentrations (Mills, 1987) there is little groundwater pumped from this subbasin. Groundwater from the Yorba Linda subbasin flows southward into the Main basin since the limited groundwater production is less than the natural replenishment from the adjacent Chino Hills. The La Habra Basin is located north of the Main Basin within the cities of La Habra and Brea. It comprises a shallow alluvial depression between the Coyote Hills and the Puente Hills. Similar to the Yorba Linda subbasin, little groundwater production occurs in the La Habra Basin due to low transmissivity and poor water quality (high TDS). Hydrogeologic studies have indicated that 2,200 to 5,500 afy of groundwater flows out of the La Habra Basin in two areas: southerly into the Main Basin along the Brea GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-5 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY Creek drainage between the East and West Coyote Hills and westerly into the Central basin in Los Angeles County (James M. Montgomery, 1977; Ramsey, 1980; OCWD, 1994). Four relatively flat elevated areas, known as mesas, occur along the coastal boundary of the basin. The mesas were formed by ground surface uplift along the Newport Inglewood Fault Zone. Ancient meandering of the Santa Ana River carved notches through the uplifted area and left behind sand- and gravel-filled deposits beneath the lowland areas between the mesas, known as gaps (Poland et al., 1956). Groundwater in the shallow aquifers within the gaps is susceptible to seawater intrusion. The Talbert and Alamitos seawater intrusion barriers were constructed to address this problem. Locations of mesas and details of seawater barrier operations are discussed in Section 3.6. 2.2 DETERMINATION OF TOTAL BASIN VOLUME A vast amount of fresh water is stored within the basin, although only a fraction of this water can be removed practically using pumping wells and without causing physical damage such as seawater intrusion or the potential for land subsidence (Alley, 2006). Nonetheless, it is important to note the total volume of groundwater that is within the active flow system, i.e., within the influence of pumping and recharge operations. OCWD used its geographic information system and the aquifer system boundaries described in detail in Section 2.8 to calculate the total volume of each of the three major aquifer systems as well as the intervening aquitards. The total volume was calculated by multiplying the area and thickness of each hydrogeologic unit. Because groundwater fills the pore spaces that represent typically between 20 and 30 percent of the total volume, the total volume was multiplied by this porosity percentage to arrive at a total groundwater volume. Assuming the basin is completely full, based on District estimates, the total amount of fresh groundwater stored in the basin is approximately 66 million acre-feet (maf), as shown in Table 2-1. TABLE 2-1 ESTIMATED BASIN GROUNDWATER STORAGE BY HYDROGEOLOGIC UNIT (Volumes in Acre-feet) Hydrogeologic Unit Pressure Area Forebay Total Shallow Aquifer System 3,800,000 1,200,000 5,000,000 Aquitard 900,000 200,000 1,100,000 Principal Aquifer System 24,300,000 8,600,000 32,900,000 Aquitard 1,600,000 300,000 1,900,000 Deep Aquifer System 18,800,000 6,300,000 25,100,000 Total 49,400,000 16,600,000 66,000,000 Notes: 1. Volumes calculated using the 3-layer basin model surfaces with ArcInfo Workstation GRID. 2. A porosity of 0.25 was assumed for aquifer systems. 3. A porosity of 0.30 was assumed for aquitards. 2-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-7 For comparison, DWR (1967) estimated that about 38 maf of fresh water is stored in the groundwater basin when full. DWR used a factor known as the specific yield to calculate this volume. The specific yield (typically between 10 and 20 percent) is the amount of water that can be drained by gravity from a certain volume of aquifer and reflects the soil’s ability to retain and hold a significant volume of water due to capillary effects. Thus, DWR’s drainable groundwater volume, although technically correct, is roughly half of OCWD’s estimate of total groundwater volume in the basin. 2.3 WATER BUDGET OCWD staff developed a hydrologic budget (inflows and outflows) for the purpose of constructing the Basin Model and for evaluating basin production capacity and recharge requirements. The key components of the budget include measured and unmeasured (estimated) recharge, groundwater production, and subsurface flows along the coast and across the Orange/Los Angeles County line. Because the basin is not operated on an annual safe-yield basis, the net change in storage in any given year may be positive or negative; however, over the period of several years, the basin must be maintained in an approximate balance. Table 2-2 presents the components of a balanced basin water budget (no annual change in storage) and does not represent data for any given year. The annual budget presented is based on the following assumptions: average precipitation, accumulated overdraft of 400,000 af, recharge of 235,000 af at the Forebay recharge facilities, and adjusted groundwater production so that total basin inflows and outflows are equal. The 235,000 af of Forebay recharge consists of 148,000 af of Santa Ana River baseflow, 50,000 af of Santa Ana River stormflow, and 37,000 af of GWR System water. The major components of the water budget are described in the following sections. 2.3.1 MEASURED RECHARGE Measured recharge consists of all water artificially recharged at OCWD’s Forebay percolation facilities and water injected at the Talbert Barrier and on the Orange County side of the Alamitos Barrier. Santa Ana River stormflows and baseflows serve as the primary source of recharge in the Forebay. OCWD’s Talbert Barrier is a series of injection wells that span the 2.5-mile wide Talbert Gap, between the Newport and Huntington Beach mesas. A blend of imported and purified water is injected into multiple aquifers that are used for municipal supply. Over 95 percent of the injected water flows inland and becomes part of the basin’s replenishment supply. The Alamitos Barrier is a series of wells injecting a blend of imported and purified water into multiple aquifer zones that span the Alamitos Gap at the Los Angeles/Orange County line. Essentially all of the injected water flows inland, replenishing groundwater basins in the two counties. From inspection of groundwater contour maps, it appears that roughly one-third of the Alamitos Barrier injection water remains within or flows into Orange County. ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY TABLE 2-2 REPRESENTATIVE ANNUAL BASIN WATER BUDGET FLOW COMPONENT Acre-feet INFLOW Measured Recharge 1. Forebay recharge facilities 2. Talbert Barrier injection 3. Alamitos Barrier injection, Orange County portion only Subtotal: 235,000 35,000 2,500 272,500 Estimated Unmeasured Recharge (average precipitation) 1. Inflow from La Habra basin 2. Recharge from foothills into Irvine subbasin 3. Areal recharge from rainfall/irrigation into Main basin 4. Recharge from foothills into Yorba Linda subbasin 5. Subsurface inflow at Imperial Highway beneath Santa Ana River 6. Santa Ana River recharge, Imperial Highway to Rubber Dam 7. Subsurface inflow from Santiago Canyon 8. Recharge along Peralta Hills 9. Recharge along Tustin Hills 10. Seawater inflow through coastal gaps Subtotal: 3,000 14,000 17,500 6,000 4,000 4,000 10,000 4,000 6,000 500 69,000 TOTAL INFLOW: 341,500 OUTFLOW 1. Groundwater Production 2. Subsurface Outflow 333,500 8,000 TOTAL OUTFLOW: 341,500 CHANGE IN STORAGE: 0 2.3.2 UNMEASURED RECHARGE Unmeasured recharge also referred to as “incidental recharge” accounts for a significant amount of the basin’s producible yield. This includes recharge from precipitation at the basin margin along the Chino, Coyote, and San Joaquin Hills and the Santa Ana Mountains; Santa Ana River recharge between Imperial Highway and the OCWD rubber diversion dam; irrigation return flows; urban runoff; and underflow beneath the Santa Ana River and Santiago Creek. This latter refers to groundwater that enters the basin at the mouth of Santa Ana Canyon, the Santiago Creek drainage below Villa Park Dam, and seawater inflow through the gaps. Unmeasured recharge is estimated at an average of 60,000 afy. This number is derived from estimating annual changes in groundwater storage by comparing groundwater elevation changes, after subtracting losses to Los Angeles County. Net incidental recharge is used to refer to the amount of incidental recharge after accounting for groundwater losses, such as outflow to Los Angeles County. This average unmeasured recharge was substantiated during calibration of the Basin Model and is also consistent 2-8 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY with the estimate of 58,000 afy reported by Hardt and Cordes (1971) as part of a U.S. Geological Survey (USGS) modeling study of the basin. Because unmeasured recharge is one of the least understood components of the basin’s water budget, the error margin of staff’s estimate for any given year is probably in the range of 10,000 to 20,000 af. Since the unmeasured recharge is well distributed throughout the basin, the physical significance water level drawdown or mounding in any given area) of over- or underestimating the total recharge volume within this error margin is considered to be minor. 2.3.3 GROUNDWATER PRODUCTION Groundwater production from the basin, as shown in Figure 2-4, occurs from approximately 450 active wells within the District, approximately 200 of which produce less than 25 afy. FIGURE 2-4 DISTRIBUTION OF GROUNDWATER PRODUCTION GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-9 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY Groundwater production from approximately 200 large-capacity or large-system wells operated by the 21 largest water retail agencies accounted for an estimated 97 percent of the total production in 2006-07. Large-capacity wells are all metered, as required by the District Act, and individual well production has been documented since 1988. Prior to 1988, per-well production data were recorded semi-annually. Groundwater production is distributed uniformly throughout the majority of the basin with the exceptions of the Yorba Linda subbasin, the immediate coastal areas, and the foothill margins of the basin, where little to no production occurs. Increases in coastal production would lead to increased stress on the Talbert and Alamitos barriers, requiring additional barrier capacity. Inasmuch as it is technically and economically feasible, future increases in coastal groundwater demand should be addressed by wells constructed inland in areas of lower well density and higher aquifer transmissivity. The distribution of existing wells and the siting of future wells depend on many different factors, including logistics, property boundaries, hydrogeology, and regulatory guidelines. Logistical considerations include property availability, city and other political boundaries, and proximity to other water facilities. Proximity to existing water transmission pipelines can be extremely important, given the cost of new reaches of pipeline. Hydrogeologic considerations for siting a well may include: thickness of permeable aquifer units, groundwater quality, drawdown interference from nearby wells, seasonal water level fluctuations, and potential impacts to the basin such as seawater intrusion. 2.3.4 SUBSURFACE OUTFLOW Groundwater outflow from the basin across the Los Angeles/Orange County line has been estimated to range from approximately 1,000 to 14,000 afy based on groundwater elevation gradients and aquifer transmissivity (DWR, 1967; McGillicuddy, 1989). The Water Replenishment District has also indicated underflow from Orange County to Los Angeles County within the aforementioned range. Underflow varies annually and seasonally depending upon hydrologic conditions on either side of the county line. Modeling by OCWD indicated that, assuming groundwater elevations in the Central Basin remain constant; underflow to Los Angeles County increases approximately 7,500 afy for every 100,000 af of increased groundwater in storage in Orange County (see Figure 2-5). With the exception of unknown amounts of semi-perched (near-surface) groundwater being intercepted and drained by submerged sewer trunk lines and unlined flood control channels along coastal portions of the basin, no other significant basin outflows are known to occur. 2-10 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-11 FIGURE 2-5 RELATIONSHIP BETWEEN BASIN STORAGE AND ESTIMATED OUTFLOW 2.4 GROUNDWATER ELEVATION AND STORAGE CALCULATION OCWD estimates annual changes in the amount of groundwater stored in the basin using groundwater elevation measurements and aquifer storage coefficients for the three primary aquifer systems in the basin. This three-layer method involves measuring the water levels at the end of each water year at nearly every production and monitoring well in the basin. Water level measurements are contoured, as shown in Figure 2-6, and then digitized into the Geographic Information System (GIS). The GIS is then used to subtract the previous year’s water level maps from the current water year, resulting in a water level change contour map for each of the three aquifer layers. Figure 2-7 shows the water level change for the principal aquifer (layer For each of the three aquifer layers, the GIS is then used to multiply these water level changes by a grid of aquifer storage coefficients from OCWD’s calibrated basin groundwater model. This results in a storage change volume for each of the three aquifer layers, which are totaled to provide a net annual storage change for the basin. A more detailed description of the three-layer methodology is presented in OCWD’s Report on Evaluation of Orange County Groundwater Basin Storage and Operational Strategy (February 2007). 7,500 afy outflow change for each 100,000 af of overdraft -10,000 0 10,000 20,000 30,000 40,000 0 100,000 200,000 300,000 400,000 500,000 Simulated Cumulative Overdraft (af) Outflow to LA Inflow from LA June 2008 306,000 af overdraft Simulated Outflow to LA County (AFY) 7,500 afy outflow change for each 100 af of overdraft ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-6 JUNE 2008 WATER LEVELS 2-12 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-7 WATER LEVEL CHANGES GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-13 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY 2.5 ACCUMULATED OVERDRAFT CALCULATION OCWD estimates that the basin can be operated on a short-term basis with a maximum accumulated overdraft (storage reduction from full condition) of approximately 500,000 af without causing irreversible seawater intrusion and land subsidence. The estimated maximum historical accumulated basin overdraft of 500,000 to 700,000 af occurred in 1956-57 (DWR, 1967; OCWD, 2003). Until 2007, water level elevations in November 1969 were used as the baseline to represent near-full conditions. The net decrease in storage from 1969 conditions represented the accumulated overdraft. Since 2004, OCWD has participated in Metropolitan’s Conjunctive Use Program. This program allows for the storage of Metropolitan water in the Orange County groundwater basin. Figure 2-8 illustrates the basin accumulated overdraft since 1962. The accumulated overdraft including the Metropolitan Conjunctive Use water is shown in red. The blue line indicates the basin accumulated overdraft calculated without Metropolitan’s stored water. FIGURE 2-8 ACCUMULATED BASIN OVERDRAFT 0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 Jun-69 Jun-74 Jun-79 Jun-84 Jun-89 Jun-94 Jun-99 Jun-04 Jun-09 Accumulated Overdraft (AF) Cumulative Overdraft E xcludes Metropolitan Stored Water(Conjunctive Use P rogram) 2-14 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-15 2.5.1 DEVELOPMENT OF NEW METHODOLOGY The traditional full-basin benchmark of 1969 was revised in 2007. A new methodology was developed to calculate accumulated overdraft and storage change. The need for this new methodology was driven by the record-setting wet year of 2004-05, in which an unprecedented storage increase of 170,000 af was estimated by OCWD staff. During that year, water levels throughout the basin rose approximately 30 feet overall, approaching a near-full condition. Analysis showed that groundwater in storage in November 2005 was only 40,000 af less than the full basin 1969 benchmark. However, the traditional method of cumulatively adding the annual storage change each year to the previous year’s accumulated overdraft produced an accumulated overdraft of approximately 190,000 acre-feet for November 2005. The discrepancy of 150,000 af in the two different calculations indicated that the current condition could not be properly rectified back to the 1969 benchmark. This brought to light three important discoveries: • The traditional storage change calculation contained considerable uncertainty that when cumulatively added over tens of years, led to a large discrepancy in the accumulated overdraft relative to 1969. • Water level conditions in 1969 no longer represent a full basin, particularly because of changes in pumping and recharge conditions. • A more accurate storage change calculation should be based on water level changes and storage coefficients for each of the three major aquifer systems. In February 2007, the District adopted an updated approach to defining the full basin condition and calculating storage changes. This updated approach includes: • A new full-basin groundwater level based on the following prescribed conditions: o Observed historical high water levels o Present-day pumping and recharge conditions o Protective of seawater intrusion o Minimal potential for mounding at or near recharge basins • Calculation of the amount of groundwater in storage in each of the three major aquifer systems. A more detailed description of this new methodology is presented in OCWD’s Report on Evaluation of Orange County Groundwater Basin Storage and Operational Strategy (February 2007), which is included as Appendix D. 2.6 ELEVATION TRENDS Groundwater elevation profiles for the principal aquifer, generally following the Santa Ana River from Costa Mesa to the Anaheim Forebay area, are shown in Figure 2-9. The groundwater elevation profiles represent the newly-calculated full basin condition, 1969 conditions (formerly considered full), and 2007 conditions. A comparison of these profiles shows that groundwater elevations in the Forebay recharge area are relatively close while elevations in 2007 are significantly lower in the central and coastal portions of the basin than the full or 1969 conditions. ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-9 PRINCIPAL AQUIFER HISTORICAL GROUNDWATER ELEVATION PROFILES 2 4 6 8 10 12 14 16 18 20 MILES FROM COAST ALONG SANTA ANA RIVER -150 -100 -50 0 50 100 150 200 250 300 FULL BASIN (THEORETICAL) 1969 (NEAR FULL BASIN) 2007 (198,000 AF BELOW FULL) MEAN SEA LEVEL GROUND SURFACE ANAHEIM COSTA MESA PRESSURE AREA FOREBAY 2 4 6 8 10 12 14 16 18 20 MILES FROM COAST ALONG SANTA ANA RIVER -150 -100 -50 0 50 100 150 200 250 300 FULL BASIN (THEORETICAL) 1969 (NEAR FULL BASIN) 2007 (198,000 AF BELOW FULL) MEAN SEA LEVEL GROUND SURFACE ANAHEIM COSTA MESA PRESSURE AREA FOREBAY Elevation (Feet MSL) The lowering of coastal area groundwater levels relative to groundwater levels further inland in the Forebay translates into a steeper hydraulic gradient, which drives greater flow from the Forebay to the coastal areas. However, the lowering of coastal water levels also increases seawater intrusion potential. Figure 2-10 presents average groundwater elevations for the principal aquifer in the Forebay, coastal areas, and the total basin on November 1 of each year, when groundwater levels are somewhat intermediate between the late summer low and late winter high. Average values were calculated using a 1,000-foot square grid and the groundwater elevation contour map prepared each year. Groundwater elevations were estimated at each grid point using the groundwater elevation contours, and the average values were calculated for each of the three areas. A comparison of the groundwater level trends in Figure 2-10 to the changes in accumulated overdraft in Figure 2-8 provides insights into the basin’s response during filling and emptying cycles. From November 2003 to November 2005, the basin’s accumulated overdraft reduced 220,000 af due to the near-record high precipitation in water year 2004-05. During this period of refill, average groundwater levels in the coastal area increased approximately 20 feet, while groundwater levels in the Forebay increased approximately 40 feet. Between November 2005 and November 2007, basin accumulated overdraft increased approximately 100,000 af as groundwater withdrawals exceeded recharge due to several factors, including near-record low precipitation. Average groundwater levels during this period fell by 40 feet in the Forebay and coastal areas. 2-16 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-10 AVERAGE PRINCIPAL AQUIFER GROUNDWATER ELEVATIONS FOR THE FOREBAY, TOTAL BASIN, AND COASTAL AREA -80 -60 -40 -20 0 20 40 60 80 100 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Year (on November 1) Elevation (feet MSL) Forebay Area Total Basin Coastal Area Data for November 2006 are unavailable Figure 2-11 shows the locations of four wells, A-27, SA-21, SAR-1, and OCWD-CTG1, with long-term groundwater level data. Figure 2-12 presents water level hydrographs and locations of wells A-27 and SA-21, representing historical conditions in the Forebay and Pressure area, respectively. The hydrograph data for well A-27 near Anaheim Lake date back to 1932 and indicate that the historic low water level in this area occurred in 1951-52. The subsequent replenishment of Colorado River water essentially refilled the basin by 1965. Water levels in this well reached an historic high in 1994 and have generally remained high as recharge has been nearly continuous at Anaheim Lake since the late 1950s. The hydrograph for well SA-21 indicates that water levels in this area have decreased since 1970. In addition, the magnitude of the seasonal water level fluctuations has approximately doubled from pre-1990 to the present. The increased water level fluctuations are due to a combination seasonal water demand-driven pumping and participation in the Metropolitan Short-Term Seasonal Storage Program by local GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-17 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY Producers (Boyle Engineering and OCWD, 1997), which encouraged increased pumping from the groundwater basin during summer months when Metropolitan was experiencing high demand for imported water. Although this program did not increase the amount of pumping from the basin on an annual basis, it did result in greater water level declines during the summer. FIGURE 2-11 LOCATION OF LONG-TERM GROUNDWATER ELEVATION HYDROGRAPH 2-18 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-12 WATER LEVEL HYDROGRAPHS OF WELLS A-27 AND SA-21 1932 1934 1936 1938 1940 1942 1944 1946 1948 1950 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 0 20 40 60 80 100 120 140 160 180 200 Production Well A-27 Perforated Interval: 197-287 ft. bgs* 1969 1971 1973 1975 1977 1979 1981 19831985 1987 1989 1991 1993 1995 19971999 2001 2003 2005 2007 2009 *msl = mean sea level *bgs = below ground surface -80 -60 -40 -20 0 20 40 Production Well SA-21 Perforated Interval: 400-960 ft. bgs* Water Level Elevation (ft msl) Water Level Elevation (ft msl) GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-19 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY 2-20 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Figure 2-13 presents water level hydrographs and locations of two OCWD multi-depth monitoring wells, SAR-1 and OCWD-CTG1, showing the relationship between water level elevations in aquifer zones at different depths. The hydrograph of well SAR-1 in the Forebay exhibits a similarity in water levels between shallow and deep aquifers, which indicates the high degree of hydraulic interconnection between aquifers characteristic of much of the Forebay. FIGURE 2-13 WATER LEVEL HYDROGRAPHS OF WELLS SAR-1 AND OCWD-CTG1 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 -20 0 20 40 60 80 100 120 140 160 Monitoring Well SAR-1 Key Zones MP4 (367 ft. bgs*) MP12 (1284 ft. bgs*) 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 *msl = mean sea level *bgs = below ground surface -140 -120 -100 -80 -60 -40 -20 0 20 40 Monitoring Well OCWD-CTG1 Perforated Intervals (ft. bgs*) 165 - 265 425 - 725 1065 - 1225 Colored Water Zone) Water Level Elevation (ft msl) Water Level Elevation (ft msl) ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY The hydrograph of well OCWD-CTG1 is typical of the Pressure Area in that a large water level distinction is observed between shallow and deep aquifers, indicating the effects of a clay/silt layer that restricts vertical groundwater flow. Water levels in the deepest aquifer zone at well OCWD-CTG1 have higher elevations than overlying aquifers, in part, because few wells directly produce water from these zones, primarily due to their associated colored water. 2.7 LAND SUBSIDENCE Subsidence of the ground surface has been associated with groundwater withdrawal in many regions of the world. In the case of thick sedimentary groundwater basins comprised of alternating “confined” or “pressure” aquifers (permeable sands and gravels) and aquitards (less permeable silts and clays), the extraction of groundwater reduces the fluid pressure of the saturated pore spaces within the buried sediments. The pressure reduction in the deeper sediments allows the weight of the overlying sediments to compact the deeper sediments, particularly the clays and silts. If groundwater withdrawals cause water level drawdowns to be sustained for several years or more, the incremental amount of sediment compaction can eventually manifest itself in a measurable lowering of the land surface (USGS, 1999). OCWD commissioned a study by the DWR (1980) to evaluate the potential for land subsidence in the basin. Because the study was limited in scope, its findings were deemed preliminary pending further investigation. Nevertheless, the study cited survey data from the Orange County Surveyor that indicated that the land surface in the city of Santa Ana declined a maximum of 0.84 inch/year from 1956 to 1961. Surveys during the period 1970 to 1976 indicated maximum land surface declines of 0.24 inch/year in Santa Ana. Key findings of the study included the following: • Subsidence in the City of Santa Ana is apparently related to the removal of groundwater. However, it is not possible to directly correlate observed subsidence and historic water-level declines. • Subsidence in the vicinity of the City of Huntington Beach can be attributed to the removal of oil. • Most of the compaction takes place in the fine-grained sediments. • Water squeezed out of the compacted fine-grained sediments, known as “water of compaction,” results in a permanent loss of storage in fine-grained sediments. Land surface changes (rising and lowering) of similar magnitude to those noted by DWR were reported by Bawden (Bawden et al, 2001) while reviewing satellite radar images for a seismic assessment of Southern California. Bawden reported seasonal land surface changes of up to 4.3 inches (total seasonal amplitude from high to low) in the Los Angeles-Orange County area and a net decline of approximately 0.5 inch/year near Santa Ana over the period 1993 to 1999, which coincides with a period of net withdrawal of groundwater from the basin. Despite the indications of land subsidence to some degree in portions of Orange County, there has been no indication that the suggested land surface changes have caused, or are likely to cause, any structural damage in the area. By maintaining groundwater levels and basin storage within its GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-21 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY historical operating range, the potential for problematic land subsidence is reduced. Conversely, land subsidence could become a problem if the basin was overdrafted beyond the historical operating range. Groundwater withdrawals are regulated within the basin operating range, which is explained in detail in Section 6.5. In the event that land subsidence becomes a problem in a localized area, OCWD will work with local officials to investigate and remediate the problem. 2.8 GROUNDWATER MODEL DESCRIPTION In general, a groundwater flow model contains two major components: the mathematical model and the conceptual model. The mathematical model is the computer program used to solve the complex system of equations that govern the flow of groundwater. The conceptual model is the hydrogeologic framework of the area being modeled, obtained by gathering, analyzing, interpreting, and finally integrating all the geologic and hydrologic data for a given area into a conceptual understanding of how the flow system looks and behaves. For a properly-constructed model, the mathematical model needs to be appropriate for the level of detail inherent in the conceptual model. For a mathematical model solved by numerical methods, the modeled area must be divided into a mesh of grid cells – the smaller the grid cells, generally the more accurate the computations – assuming the hydrogeology can be reasonably-defined at the grid cell level of detail. Based on all the input data, the model calculates a water level elevation and fluxes for each and every grid cell of the modeled area at a given point in time. OCWD’s basin model encompasses the entire basin and extends approximately three miles into the Central Basin in Los Angeles County to provide for more accurate model results than if the model boundary stopped at the county line (see Figure 2-14). As noted previously in this chapter, the county line is not a hydrogeologic boundary, i.e., groundwater freely flows through aquifers that have been correlated across the county line. Coverage of the modeled area is accomplished with grid cells having horizontal dimensions of 500 feet by 500 feet (approximately 5.7 acres) and vertical dimensions ranging from approximately 50 to 1,800 feet, depending on the thickness of each model layer at that grid cell location. Basin aquifers and aquitards were grouped into three composite model layers thought sufficient to describe the three distinguishable flow systems referred to as the shallow, principal, and deep aquifer systems. The three model layers comprise a network of over 90,000 grid cells. The widely-accepted computer program, “MODFLOW,” developed by the USGS, was used as the base modeling code for the mathematical model (McDonald and Harbaugh, 1988). Analogous to an off-the-shelf spreadsheet program needing data to be functional, MODFLOW requires vast amounts of input data to define the hydrogeologic conditions in the conceptual model. The types of information that must be input in digital format (data files) for each grid cell in each model layer include the following: • Aquifer top and bottom elevations 2-22 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY • Aquifer lateral boundary conditions (ocean, faults, mountains) • Aquifer hydraulic conductivity and storage coefficient/specific yield • Initial groundwater surface elevation • Natural and artificial recharge rates (runoff, precipitation, percolation, injection) • Groundwater production rates for approximately 200 large system and 200 small system wells FIGURE 2-14 BASIN MODEL EXTENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-23 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY These data originate from hand-drawn contour maps, spreadsheets, and the Water Resources Management System (WRMS) historical database. Because MODFLOW requires the input data files in a specific format, staff developed a customized database and GIS program to automate data compilation and formatting functions. These data pre-processing tasks form one of the key activities in the model development process. Before a groundwater model can be reliably used as a predictive tool for simulating future conditions, the model must be calibrated to reach an acceptable match between simulated and actual observed conditions. The basin model was first calibrated to steady-state conditions to numerically stabilize the simulations, to make rough adjustments to the water budget terms, and to generally match regional groundwater flow patterns. Also, the steady-state calibration helped to determine the sensitivity of simulated groundwater levels to changes in incidental recharge and aquifer parameters such as hydraulic conductivity. Steady-state calibration of the basin model is documented in more detail in the OCWD Master Plan Report (OCWD, 1999). Typical transient model output consists of water level elevations at each grid cell that can be plotted as a contour map for one point in time or as a time-series graph at a single location. Post-processing of model results into usable graphics is performed using a combination of semi-automated GIS and database program applications. Figure 2-15 presents a simplified schematic of the modeling process. FIGURE 2-15 MODEL DEVELOPMENT FLOWCHART Define objectives Compile data Analyze data geologic cross sections X-Y trend graphs contour maps water chemistry data Develop Hydrogeologic Model aquifer boundaries transmissivity storage coefficient basin water balance Build Computer Model create grid digitize layers create data input files define model conditions Run Model Scenarios develop production/recharge alternatives set up data for each alternative output results as contour maps and hydrographs Calibrate Model match historical water levels adjust until results acceptable Revise Hydrogeologic Model revise geologic cross sections, inferred faults refine conceptual model 2-24 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY Model construction, calibration, and operation were built upon 12 years of effort by OCWD staff to collect, compile, digitize, and interpret hundreds of borehole geologic and geophysical logs, water level hydrographs, and water quality analyses. The process was composed of ten main tasks comprising over 120 subtasks. The major tasks are summarized below: 1. Finalize conceptual hydrogeologic model layers and program GIS/database applications to create properly formatted MODFLOW input data files. Over 40 geologic cross sections were used to form the basis of the vertical and lateral aquifer boundaries. 2. Define model layer boundaries. The top and bottom elevations of the three aquifer system layers and intervening aquitards were hand-contoured, digitized, and overlain on the model grid to populate the model input arrays with a top and bottom elevation for each layer at every grid cell location. Model layer thickness values were then calculated by using the GIS. 3. Develop model layer hydraulic conductivity grids. Estimates of K for each layer were based on (in order of importance): available aquifer test data, well specific capacity data, and lithologic data. In the absence of reliable aquifer test or specific capacity data for areas in Layers 1 and 3, lithology-based K estimates were calculated by assigning literature values of K to each lithology type sand, gravel, clay) within a model layer and then calculating an effective K value for the entire layer at that well location. Layer 2 had the most available aquifer test and specific capacity data. Therefore, a Layer 2 transmissivity contour map was prepared and digitized, and the GIS was then used to calculate a K surface by dividing the transmissivity grid by the aquifer thickness grid. Initial values of K were adjusted during model calibration to achieve a better match of model results with known groundwater elevations. 4. Develop layer production factors for active production wells simulated in the model. Many production wells had long screened intervals that spanned at least two of the three model layers. Therefore, groundwater production for each of these wells had to be divided among each layer screened by use of layer production factors. These factors were calculated using both the relative length of screen within each model layer and the hydraulic conductivity of each layer. Well production was then multiplied by the layer factors for each individual well. For example, if a well had a screened interval equally divided across Layers 1 and 2, but the hydraulic conductivity of Layer 1 was twice that of Layer 2, then the calculated Layer 1 and 2 production factors for that well would have been one-third and two-thirds, respectively, such that when multiplied by the total production for this well, the production assigned to Layer 1 would have been twice that of Layer 2. For the current three-layer model, approximately 25 percent of the production wells in the model were screened across more than one model layer. In this context, further vertical refinement of the model (more model layers) may better represent GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-25 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY the aquifer architecture in certain areas but may also increase the uncertainty and potential error involved in the amount of production assigned to each model layer. 5. Develop basin model water budget input parameters, including groundwater production, artificial recharge, and unmeasured recharge. Groundwater production and artificial recharge volumes were applied to grid cells in which production wells or recharge facilities were located. The most uncertain component of the water budget – unmeasured or incidental recharge – was applied to the model as an average volume based on estimates calculated annually for the OCWD Engineer’s Report. Unmeasured recharge was distributed to cells throughout the model, but was mostly applied to cells along margins of the basin at the base of the hills and mountains. The underflow component of the incidental recharge represents the amount of groundwater flowing into and out of the model along open boundaries. Prescribed groundwater elevations were assigned to open boundaries along the northwest model boundary in Los Angeles County; the ocean at the Alamitos, Bolsa, and Talbert Gaps; the mouth of the Santa Ana Canyon; and the mouth of Santiago Creek Canyon. Groundwater elevations for the boundaries other than the ocean boundaries were based on historical groundwater elevation data from nearby wells. The model automatically calculated the dynamic flow across these open boundaries as part of the overall water budget. 6. Develop model layer storage coefficients. Storage coefficient values for portions of model layers representing confined aquifer conditions were prepared based on available aquifer test data and were adjusted within reasonable limits based on calibration results. 7. Develop vertical leakance parameters between model layers. Vertical groundwater flow between aquifer systems in the basin is generally not directly measured, yet it is one of the critically-important factors in the model’s ability to represent actual basin hydraulic processes. Using geologic cross-sections and depth-specific water level and water quality data from the OCWD multi-depth monitoring well network, staff identified areas where vertical groundwater flow between the modeled aquifer systems is either likely to occur or be significantly impeded, depending on the relative abundance and continuity of lower-permeability aquitards between model layers. During model calibration, the initial parameter estimates for vertical leakance were adjusted to achieve closer matches to known vertical groundwater gradients. 8. Develop groundwater contour maps for each model layer to be used for starting conditions and for visual comparison of water level patterns during calibration. Staff used observed water level data from multi-depth and other wells to prepare contour maps of each layer for November 1990 as a starting point for the calibration period. Care was taken to use wells screened within the appropriate vertical interval representing each model 2-26 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-27 layer. The hand-drawn contour maps were then digitized and used as model input to represent starting conditions. 9. Perform transient calibration runs. The nine-year period of November 1990 to November 1999 was selected for transient calibration, as it represented the period corresponding to the most detailed set of groundwater elevation, production, and recharge data. The transient calibration process and results are described in Section 2.8.1. 10. Perform various basin production and recharge scenarios using the calibrated model. Criteria for pumping and recharge, including facility locations and quantities, were developed for each scenario and input for each model run. 2.8.1 MODEL CALIBRATION Calibration of the transient basin model involved a series of simulations of the period 1990 to 1999, using flow and water level data. The time period selected for calibration represents a period during which basic data required for transient calibration were essentially complete (compared to pre-1990 historical records). The calibration period spans at least one “wet/dry” rainfall cycle. water level data from almost 250 target locations were used to determine if the simulated water levels adequately matched observed water levels. As shown in Figure 2-16, the calibration target points were densely distributed throughout the basin and also covered all three model layers. After each model run, a hydrograph of observed versus simulated water levels was created and reviewed for each calibration target point. In addition, a groundwater elevation contour map for each layer was also generated from the simulated data. The simulated groundwater contours for all three layers were compared to interpreted contours of observed data (November 1997) to assess closeness of fit and to qualitatively evaluate whether the simulated gradients and overall flow patterns were consistent with the conceptual hydrogeologic model. November 1997 was chosen for the observed versus simulated contour map comparison since these hand-drawn contour maps had already been created for the prior steady state calibration step. Although November 1997 observed data were contoured for all three layers, the contour maps for Layers 1 and 3 were somewhat more generalized than for Layer 2 due to a lower density of data points (wells) in these two layers. Depending on the results of each calibration run, model input parameters were adjusted, including hydraulic conductivity, storage coefficient, boundary conditions, and recharge distribution. Time-varying head boundaries along the Orange/Los Angeles County line were found to be extremely useful in obtaining a close fit with observed historical water levels in the northwestern portion of the model. Fifty calibration runs were required to reach an acceptable level of calibration in which model-generated water levels were within reasonable limits of observed water level elevations during the calibration period. Figures 2-17 through 2-19 show examples of hydrographs of observed versus simulated water levels for three wells used as calibration targets. ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-16 BASIN MODEL CALIBRATION WELLS 2-28 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-29 Figure 2-17 CALIBRATION HYDROGRAPH FOR MONITORING WELL AM-5A FIGURE 2-18 CALIBRATION HYDROGRAPH FOR MONITORING WELL SC-2 80 100 120 140 160 180 200 ( ) (Model Layer 2 Santiago Pit Area) Observed Run 10 Run 50 11/1/90 11/1/92 11/1/94 11/1/96 11/1/98 Port Depth: 412 ft bgs. 80 100 120 140 160 180 200 ( ) (Model Layer 1 Anaheim Forebay) Observed Run 10 Run 50 11/1/90 11/1/92 11/1/94 11/1/96 11/1/98 Screened Interval: 168-175 ft bgs. Water Level Elevation (ft msl) Water Level Elevation (ft msl) ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY 2-30 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE FIGURE 2-19 CALIBRATION HYDROGRAPH FOR MONITORING WELL GGM-1 Noteworthy findings of the model calibration process are summarized below: • The model was most sensitive to adjustments to hydraulic conductivity and recharge distribution. In other words, minor variations in these input parameters caused significant changes in the model water level output. • The model was less sensitive to changes in storage coefficient, requiring order-of-magnitude changes in this parameter to cause significant changes in simulated water levels, primarily affecting the amplitude of seasonal water level variations. • The vast amount of observed historical water level data made it readily evident when the model was closely matching observed conditions. • Incidental (unmeasured) recharge averaging approximately 70,000 afy during the 1990-1999 period appeared to be reasonable, as the model was fairly sensitive to variations in this recharge amount. • Groundwater outflow to Los Angeles County was estimated to range between 5,000 and 12,000 afy between 1990 and 1999, most of this occurring in Layers 1 and 3. • Groundwater flow at the Talbert Gap was inland during the entire model calibration period, indicating moderate seawater intrusion conditions. Model- derived seawater inflow ranged from 500 to 2,700 afy in the Talbert Gap and is consistent with chloride concentration trends during the calibration period that indicated inland movement of saline groundwater in these areas. • Model-derived groundwater inflow from the ocean at Bolsa Gap was only 100- 200 afy due to the Newport-Inglewood Fault zone, which offsets the Bolsa -60 -40 -20 0 20 40 60 ( ) (All Three Model Layers Garden Grove) 11/1/90 11/1/92 11/1/94 11/1/96 11/1/98 Port Depths: 150 ft bgs 1,074 ft bgs 2,011 ft bgs L1 Observed L1 Simulated L2 Observed L2 Simulated L3 Observed L3 Simulated Water Level Elevation (ft msl) ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY aquifer and significantly restricts the inland migration of saline water across the fault. • Model adjustments (mainly hydraulic conductivity and recharge) in the Santiago Pits area in Orange significantly affected simulated water levels in the coastal areas. • Model reductions to the hydraulic conductivity of Layer 2 (Principal aquifer system) along the Peralta Hills Fault in Anaheim/Orange had the desired effect of steepening the gradient and restricting groundwater flow across the fault into the Orange area. These simulation results were consistent with observed hydrogeologic data indicating that the Peralta Hills Fault acts as a partial groundwater barrier. • Potential unmapped faults immediately downgradient from the Santiago Pits appear to restrict groundwater flow in the Principal aquifer system, as evidenced by observed steep gradients in that area, which were reproduced by the model. As with the Peralta Hills Fault, an approximate order-of- magnitude reduction in hydraulic conductivity along these suspected faults achieved the desired effect of reproducing observed water levels with the model. 2.8.2 MODEL ADVISORY PANEL The model development and calibration process was regularly presented to and reviewed by a Model Advisory Panel. This technical panel consisted of four groundwater modeling experts who were familiar with the basin and highly qualified to provide insight and guidance during the model construction and calibration process. Twelve panel meetings were held between 1999 and 2002. The panel was tasked with providing written independent assessments of the weaknesses, and overall validity and usefulness of the model in evaluating various basin management alternatives. Two memoranda were prepared: one at the completion of the steady-state model calibration and steady-state scenarios (Harley et al., 1999) and one at the completion of the transient model calibration and initial transient basin operational scenarios (Harley et al., 2001). Key conclusions and findings of the panel regarding the transient model are summarized below. • Transient modeling has substantially improved the overall understanding of processes and conditions that determine how and why the basin reacts to pumping and recharge. This improved understanding, coupled with the model’s ability to simulate existing and possible future facilities and alternative operations, significantly improves the District’s potential ability to enhance and actively manage basin water resources. • Modeling has helped verify major elements of the basin conceptual model and has been instrumental in clarifying: o Variations in the annual water balance o Hydrostratigraphy of the basin o Horizontal flow between basin subareas GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-31 ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY o The potential degree of interconnection and magnitude of vertical flow between major aquifers o The potential hydraulic significance of the Peralta Hills Fault in the Anaheim Forebay o Variations in aquifer hydraulic properties o The relative significance of engineered versus natural recharge and groundwater outflow within the basin o Numerous other issues and conditions. • The ability of the model to simulate known and projected future conditions will evolve and improve as new data become available and updated calibration runs are completed. • Parameters used to set up the model appear to be within limits justified by known, estimated, and assumed subsurface conditions based upon available historic data. • Initial transient calibration completed using a nine-year calibration period (1990-1999) is considered adequate to confirm the initial validity of the model for use in evaluating a variety of potential future projects and conditions. • Areas of the basin that could benefit from future exploration, testing, monitoring, analysis and/or additional model calibration were identified. • The model is not considered appropriate for assessing detailed local impacts related to new recharge facilities or well fields. These impacts should be assessed using more detailed local submodels and by conducting detailed field studies. • The model does not, nor is it intended to, address water supply availability, cost, water quality, or land subsidence. Recommendations of the panel included suggestions that thorough documentation be prepared on model configuration and calibration and that the model calibration period be extended as new data become available. 2.8.3 TALBERT GAP MODEL Between 1999 and 2000, OCWD contracted with Camp Dresser & McKee Inc. to develop a detailed groundwater flow model of the Talbert Gap and surrounding area for the purpose of evaluating and estimating the amount and location of fresh water injection wells needed to control seawater intrusion under current and projected future basin conditions. The Talbert Gap modeling effort was undertaken as part of the design scope of work for Phase 1 of the GWR System, which included expansion of the existing Talbert Barrier. The configuration and initial calibration of the Talbert Gap Model and further model refinement and calibration were documented by Camp Dresser & McKee Inc. (2000, 2003). Consistent with the Basin Model Advisory Panel’s findings, OCWD determined that a more detailed model of the Talbert Gap was necessary to evaluate the local water level changes associated with various potential injection barrier alignments and flow rates. The Talbert model comprises an area of 85 square miles, 13 Layers (seven aquifers 2-32 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 2-33 and six aquitards), and 509,000 grid cells (250 feet x 250 feet horizontal dimensions). Figures 2-20 and 2-21 show the model area and layering schematic, respectively. FIGURE 2-20 TALBERT GAP MODEL AND BASIN MODEL BOUNDARIES ---PAGE BREAK--- SECTION 2 BASIN HYDROGEOLOGY FIGURE 2-21 TALBERT GAP MODEL AQUIFER LAYERING SCHEMATIC SW Talbert Barrier NE Pacific Ocean 5,000 ft 2,500 1,000 0 ft msl 2,000 aquitard Aquifer Name Key findings of the Talbert Gap model are summarized below. • Depending on the amount of basin production, particularly near the Talbert Barrier, 30 mgd (approximately 34,000 afy) of injection will substantially raise water levels, yet may not be sufficient to fully prevent seawater intrusion in the Talbert Gap. Additional injection wells beyond those planned for Phase 1 of the GWR System may be required. • Under projected 2020 conditions, the future Talbert Barrier may require an annual average injection rate of up to 45 mgd based on the results of existing analyses. This estimated future injection requirement will be further evaluated as additional data are collected. • The Talbert model inland boundaries do not coincide with hydrologic or geologic features, e.g., recharge area, faults. Therefore, simulated water levels are highly influenced by the time-varying water levels specified along the boundaries. For future Talbert model predictive runs, the basin model should be used to generate water levels that can then be specified along the inland Talbert model boundaries. • The Talbert model was less sensitive to adjustment hydraulic conductivity and storage coefficient than the basin model, primarily because of the stronger influence of the specified-head boundaries in the Talbert model. 2-34 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING 3 GROUNDWATER MONITORING OCWD conducts a comprehensive monitoring program of the groundwater basin and surface water supplies in the watershed to properly manage water supplies and to safeguard the basin’s water quality. This section describes OCWD’s basin monitoring programs, including the following: • Groundwater monitoring locations; • Water sample collection and analysis procedures; • Monitoring of production rates, groundwater elevation, groundwater quality, and recharge water quality; and • Seawater intrusion monitoring and prevention. 3.1 Introduction For its size, the Orange County groundwater basin is one of the world’s most extensively monitored. The District’s comprehensive monitoring program tracks dynamic basin conditions including groundwater production, storage, elevations, and water quality. OCWD’s monitoring program has helped improve groundwater management throughout the basin by: • Establishing on an annual basis the safe and sustainable level of groundwater production. • Determining the extent of seawater intrusion and subsequently building improvements to seawater barriers to prevent and reverse such intrusion. • Discovering areas of groundwater contamination to protect public health and beneficial use of groundwater, and to begin remediation efforts at an early stage. • Assuring that the groundwater basin is managed in full compliance with all relevant laws and regulations. 3.2 Collection and Management of Monitoring Data Data are collected through a vast network of production and monitoring wells at frequencies necessary for short- and long-term trend analyses. The wells are located throughout the basin to enable not only analysis of the basin as a whole but also to focus on local or sub-regional investigations. Multi-depth monitoring wells provide depth-specific water level and quality data allowing analysis of the basin’s multiple- aquifer configuration. The network of nearly 700 municipal drinking water, private domestic, industrial, irrigation, and monitoring wells is used to collect data for a variety of purposes. A list of GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 3-1 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING each OCWD monitoring well with well type, cased depth, and top and bottom perforation is shown in Appendix E. Figure 3-1 shows the locations of over 200 production wells that extract groundwater for municipal use. individual well production rates for large-capacity wells have been collected since 1988. Monitoring wells, shown in Figure 3-2, are operated by OCWD to supplement the water quality data collected at production wells and to fill data gaps. FIGURE 3-1 PRODUCTION WELL LOCATIONS 3-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING FIGURE 3-2 OCWD MONITORING WELL LOCATIONS Note: Monitoring wells constructed and/or owned by other entities besides OCWD are not shown. Data collected in OCWD’s monitoring program are stored in the District’s electronic database, the Water Resources Management System (WRMS). WRMS contains comprehensive well information, current and historical data, as well as information on sub-surface geology, groundwater modeling, and water quality. This database provides for subsequent retrieval and analysis of data or preparation of data reports and data submittals to other agencies. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 3-3 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING 3-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 3.3 Water Sample Collection and Analysis OCWD’s laboratory is state-certified to perform bacteriological, inorganic, and organic analyses (see Figure 3-3). The District utilizes state-certified contractor laboratories to analyze asbestos, dioxin, and radiological samples. Analytical methods approved by the California Department of Public Health (CDPH) or U.S. Environmental Protection Agency (EPA) are used for analyzing water quality samples for the drinking water compliance program. As new chemicals are regulated, the OCWD laboratory develops the analytical capability and becomes certified in the approved method to process compliance samples. The amount of samples taken is dynamic, ranging from 600 to 1,700 samples in any given month. Water quality samples are collected in the field in accordance with approved federal and state procedures and industry-recognized quality assurance and control protocols to ensure that sampled water is representative of ambient groundwater (or surface water) conditions. Water samples are collected in method-specific containers, stored in coolers at approximately 4oC, and delivered to state-certified laboratories, researchers, or contract laboratories for analysis. The majority of samples are delivered to the laboratory on the day of sample collection. When samples must be shipped, they are sent overnight for next-day delivery. Site conditions, field measurements of selected water quality parameters (temperature, pH, electrical conductivity, and dissolved oxygen), and other relevant sample observations are recorded in field notebooks at each sampling location, and a chain-of-custody form is completed for each sample collected per site. Sampling occurs in a variety of terrains and occasionally in inclement weather and outside normal business hours. FIGURE 3-3 OCWD’S STATE CERTIFIED NEW LABORATORY ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 3-5 Well Cluster Nested Well Westbay Multipoint Well FIGURE 3-4 THREE COMMON MONITORING WELL DESIGNS Production wells that provide water for drinking water, irrigation/agriculture, and industrial uses generally have well screens located in the permeable, water-bearing zones that may tap multiple aquifers. Therefore, water quality samples collected from these wells may represent water from one or more aquifers; some permeable zones may provide greater contribution than others to the overall water sample. In contrast, monitoring wells are designed and constructed with well screens placed at a specific depth and length to provide water quality at desired zones within an aquifer. Figure 3-4 illustrates the three monitoring well designs used for basinwide water quality monitoring activities: multi-point, nested, and cluster. The multi-point well is a Westbay well design that contains a single casing with sampling ports located at specific depths in the underlying aquifers (Figure 3-5). Individual sampling points are hydraulically separated by packers. A computer-assisted sampling probe is used to collect a water sample at the desired depth. The sampling port has direct hydraulic connection between the port and the aquifer, allowing groundwater to flow into a detachable stainless steel sample container. OCWD has more than 50 multi-point wells ranging from a few hundred feet to over 2,000 feet in depth. FIGURE 3-5 MULTIPORT WELL DESIGN DETAIL Stainless steel sample container Sampling port Multiple sampling ports 3 18 Well depths, ft 255 1950 Stainless steel sample container Sampling port Multiple sampling ports 3 18 Well depths, ft 255 1950 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING A nested well design consists of a single borehole with individual monitoring wells screened at specific depths and completed in the borehole. A cluster is represented by individual monitoring wells completed with single casings at targeted depths within close proximity of each other. A “single point” monitoring well is one individual monitoring well that typically is screened over about 10 to 30 feet of sediments. The primary difference between the multi-point wells and the nested, cluster or single-point monitoring wells is the method of sample collection. Westbay multi-point wells do not require purging of groundwater prior to sample collection. In contrast, single point monitoring wells use a submersible pump to purge groundwater from the well and the surrounding formation until “ambient” or steady state conditions are obtained as determined by steady, continuous field measurements of pH, electrical conductivity, and temperature. Between forty to nearly 2,000 gallons of groundwater may be purged from a monitoring well prior to sample collection. Generally, a truck equipped with one or more submersible pumps and a portable generator is used to purge and sample groundwater from single-point monitoring wells. Portable submersible pump and reel systems provide additional flexibility to increase the efficiency of sampling monitoring wells without dedicated pumps. One truck is outfitted with a dual system of submersible pumps and environmental hoses installed separately on hydraulic booms to sample two wells simultaneously (see Figure 3-6). FIGURE 3-6 DUAL BOOM WATER QUALITY SAMPLING VEHICLE 3-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING 3.4 Production and Groundwater Elevation Monitoring Approximately 200 large-capacity municipal supply wells account for 97 percent of production. Large-capacity well owners, who are required by the District Act to report to OCWD every six months, voluntarily report groundwater production for each of their wells. The production volumes are verified by OCWD field staff. Data are used to assess the Replenishment Assessment, quantify total basin pumping, calibrate the basin model described in Section 2.8, and to evaluate seasonal groundwater level fluctuations. As an example, Figure 3-7 illustrates seasonal groundwater production trends in three municipal wells. FIGURE 3-7 EXAMPLES OF SEASONAL WELL PUMPING PATTERNS 2004 2005 2006 2007 2008 2009 0 100 200 300 400 500 600 p p g IRWD-C8 GG-22 O-25 Groundwater Production per Month (AF) Groundwater elevation (or level) data are measured at least semi-annually at nearly every production and monitoring well. Over 1,000 individual measurement points are monitored for water levels on a or basis to evaluate short-term effects of pumping or recharge operations. More frequent water level measurements are collected at selected monitoring wells in the vicinity of OCWD’s recharge facilities, seawater barriers, and areas of special investigation where drawdown, water quality impacts, or contamination are of concern. The number of municipal wells that are monitored varies from year to year depending on well maintenance, abandonment, new well construction, and related factors. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 3-7 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING 3.5 Water Quality Monitoring In 2008, nearly 14,000 groundwater samples were collected and analyzed to comply with state and federal regulations and to enable OCWD to monitor the water quality of the basin. OCWD conducts the EPA/CDPH compliance sampling and reporting for Producers wells. The number of water quality samples varies each year in response to regulatory requirements and to gain a better understanding of the basin, as shown in Figure 3-8. A summary of the well types, the number of wells, and the number of sample points is presented in Table 3-1. FIGURE 3-8 GROUNDWATER AND SURFACE SITE SAMPLES COLLECTED BY OCWD 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Number of Samples CALENDAR YEAR TABLE 3-1 DISTRIBUTION OF WELLS IN BASINWIDE MONITORING PROGRAM Well Type No. of Wells No. of Individual Sample Points Drinking Water Wells 228 228 Industrial And Irrigation wells 123 123 OCWD Monitoring Wells (excluding seawater monitoring) 254 728 OCWD Seawater Intrusion Monitoring Wells 93 244 Total 698 1323 3-8 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING Samples collected throughout the basin are used to monitor the impacts of basin extraction, determine the effectiveness of the seawater intrusion barriers, assess the impacts of historic and current land uses, and serve as a sentinel or early warning of emerging contaminants of concern. The District’s comprehensive water quality monitoring programs fall roughly into three categories: compliance with permits and drinking water regulations, OCWD Board approved projects for research and other purposes, and basin management. 3.5.1 DRINKING WATER REGULATIONS The Federal Safe Drinking Water Act (SDWA) directs the EPA to set health-based standards (maximum contaminant levels or MCLs) for drinking water to protect public health against both naturally-occurring and man-made contaminants. EPA administers the SDWA at the federal level and establishes MCLs for bacteriological, inorganic, organic, and radiological constituents (U.S. Code Title 42, and Code of Federal Regulations Title 40). California administers and enforces the federal program and has adopted its own SDWA, which may contain more stringent state requirements (California Health and Safety Code, Section 116350 and related sections). The regulations implementing the California SDWA are referred to as the Title 22 Drinking Water Standards. Since the 1970s, the number of chemicals regulated in groundwater sources has increased more than four-fold. OCWD monitors more than 100 regulated and unregulated chemicals at a specified monitoring frequency established by regulation as shown in Table 3-2. Typically, about one-third of the drinking water wells are sampled every year for general minerals, metals, and secondary MCL constituents (color, odor, TDS, sodium, chloride, alkalinity, etc.). VOCs and nitrate are sampled annually at every well. Quarterly monitoring is required if VOCs are detected or if nitrate concentrations exceed 50 percent of the MCL. In addition, OCWD monitors wells routinely for selected chemicals on the unregulated lists, chemicals with Notification Levels, or new chemicals of concern. Analyses for organic chemicals (SOCs) including tests for herbicides, pesticides, plasticizers, and other semi-volatile organics require use of twelve or more analytical methods. Newly-constructed wells are monitored for SOCs for four consecutive quarters to provide seasonal data for CDPH to assess the long-term monitoring frequency in their vulnerability assessment. In addition to the regulated chemicals, both EPA and the CDPH require monitoring for unregulated chemicals. Unregulated chemicals do not have an established drinking water standard, but are new priority chemicals of concern. Monitoring provides information regarding their occurrence and levels detected in drinking water supply wells as the first assessment step to determine if the establishment of a standard (MCL) is necessary. Wells must be sampled twice within twelve months to comply with the unregulated chemical monitoring rules. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 3-9 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING TABLE 3-2 MONITORING OF REGULATED AND UNREGULATED CHEMICALS Chemical Class Frequency Monitoring Notes Inorganic - General Minerals Once every 3 years Inorganic - Trace Metals Once every 3 years Nitrate and nitrite Annually New wells sampled quarterly for 1st year Detected > 50% MCL Quarterly Perchlorate New wells sampled quarterly for 1st year Detected > DLR Quarterly Detection limit = 4 ppb Non-detect at < DLR Once every 3 years OCWD will monitor at least annually Volatile organic chemicals (VOC) Annually New wells sampled quarterly for 1st year Detected VOC Quarterly organic chemicals (SOC) New wells sampled quarterly for 1st year; if non-detect, susceptibility waiver for 3 years Atrazine and simazine Once every 3 years Radiological New wells sampled quarterly for 1st year (initial screening) to determine reduced monitoring frequency for each radionuclide Detected at > 1/2 MCL < MCL Once every 3 years Per radionuclide Reduced monitoring after initial year Detected at < 1/2 MCL Once every 6years Per radionuclide Reduced monitoring after initial year Non-detect at < DLR Once every 9 years Per radionuclide Reduced monitoring after initial year DHS : 4-Inorganic and 5-organic chemicals DHS UCMR - required testing for all new wells EPA UCMR1 - List 1: 1-Inorganic and 10-organic chemicals EPA UCMR1 - List 2: 13-Organic chemicals EPA UCMR2 - List 1: 10 organic chemicals All water utilities serving >10,000 people. Monitoring period: 2008- 2010 EPA UCMR2 - List 2: 15 organic chemicals All water utilities serving population >100,000 and EPA selected systems serving <100,000 population. Monitoring period: 2008- 2010 Comments EPA UCMR1 - no longer required by EPA; sampling period was 2001-2003; received waiver April '08 from DPH of non vulnerable so no further testing required. New wells were being tested since 2001 to Apr. 08 (waiver granted by DPH) Current EPA program: Jan 2008 - Dec. 2010 EPA and DPH Unregulated Chemicals Two required samples: Vulnerable period: May-Jun-Jul-Aug-Sep 5 to 7 months before or after the sample collected in the vulnerable period. No further testing after completing the two required sampling events Monitoring completed for existing wells in 2001- 2003; new wells tested during 1st year DPH Title 22 Drinking Water Monitoring Frequency Regulated Chemicals 3.5.2 MONITORING FOR CONTAMINANTS IN THE BASIN OCWD has taken a proactive role in monitoring the basin for VOCs for over twenty years. This extensive monitoring program that tests agricultural, industrial, private, and domestic wells, led to the discovery of the El Toro MCAS solvent plume, discussed in Section 5.5. In response to the detection of VOCs in Anaheim and Fullerton over 100 monitoring wells, many in cluster well configuration were drilled to provide a broad range of monitoring points to define the areal extent of VOC contamination. Monitoring wells are sampled as frequently as quarterly in areas of localized high concentrations of solvents and annually at other locations. Other chemicals are added to the monitoring program when concern arises. In the case of the North Basin 3-10 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING Groundwater Protection Project, described in Section 5.8, OCWD monitors for VOCs, 1,4-dioxane, and other constituents. Monitoring gaps for regulated and unregulated chemicals occur in areas within Irvine where drinking water wells were not operating on a regular basis. OCWD’s fills the data gaps with the non-potable well monitoring program. Monitoring wells and accessible agricultural wells are sampled for volatile organics, general minerals, and selected chemicals of concern to provide water quality information in this area of the basin. 3.6 Seawater Intrusion Monitoring and Prevention Monitoring and preventing the encroachment of seawater into fresh groundwater zones along coastal Orange County is a major basin management issue. Seawater encroachment also represents a key factor in determining the basin operating range in terms of the maximum accumulated overdraft. Besides seawater intrusion, other identified sources of coastal groundwater salinity include connate water (water trapped in the pore spaces of sediments at the time of deposition) and brines disposed of at the ground surface during past oil production (Poland et al., 1956; DWR, 1961; DWR, 1968; J.M. Montgomery, 1974). The primary avenues for seawater intrusion into the basin are permeable sediments underlying topographic lowlands or “gaps” between the erosional remnants or “mesas” of the Newport-Inglewood Uplift, as shown in Figure 3-9. The susceptible locations are the Talbert, Bolsa, Sunset, and Alamitos Gaps. Seawater intrusion through the Alamitos and Talbert Gaps is controlled via the operation of seawater barriers consisting of injection wells. The Alamitos Barrier has been operated since 1965 under a joint funding agreement between OCWD and Los Angeles County Department of Public Works (LACDPW) and a joint management committee consisting of OCWD, LACDPW, and other local stakeholders including the Water Replenishment District, City of Long Beach, and Golden State Water Company. OCWD has operated the Talbert Seawater Barrier since 1975. Flow and pressure readings are used to maximize total injection without over pressurizing the wells. A coastal seawater monitoring program assesses the effectiveness of the Alamitos and Talbert Barriers and tracks salinity levels in the Bolsa and Sunset Gaps. Over 425 monitoring and production wells are sampled semi-annually to assess water quality conditions during periods of lowest production (winter) and peak demands (summer). water levels are measured in many of the coastal wells to evaluate seasonal effects of pumping and the operation of the injection barrier. A small subset of coastal wells is equipped with pressure transducers and data loggers for twice daily measurement and recording of water level conditions. Key groundwater monitoring parameters used to determine the effectiveness of the barriers include water level elevations, chloride, TDS, electrical conductivity, and bromide. Groundwater elevation contours for the aquifers most susceptible to seawater intrusion are prepared to evaluate the freshwater mound developed by the barrier injection wells and to determine if it is sufficient to prevent the inland movement of saline water. The Talbert Gap chloride concentration contours shown in Figure 3-10 illustrate both the historical inland progression of groundwater salinity and its recent GROUNDWATER MANAGEMENT PLAN UPDATE 2009 3-11 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING reversal due to injecting large volumes of water and basin management practices employed in the last four years. FIGURE 3-9 SEAWATER BARRIER LOCATIONS 3-12 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING FIGURE 3-10 LANDWARD MOVEMENT OF 250 MG/L CHLORIDE CONCENTRATION CONTOUR In addition to contour maps, OCWD staff prepares and reviews chloride concentration trends at individual wells to identify and evaluate intrusion in specific aquifer zones, Chloride concentration trend charts for two of those wells are shown in Figure 3-11 with their locations shown in Figure 3-10. GROUNDWATER MANAGEMENT PLAN UPDATE 2009 3-13 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING FIGURE 3-11 EXAMPLE CHLORIDE CONCENTRATION TREND CHARTS DOMESTIC WELL LIBM-HB NEAR BEACH BLVD. AND TALBERT AVE., HUNTINGTON BEACH CALENDAR YEAR MONITORING WELL OCWD BSO-2/1 BOLSA CHICA AREA, NEAR WINTERSBURG CHANNEL CALENDAR YEAR 3-14 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING 3.7 Monitoring Quality of Recharge Water OCWD conducts an extensive program to monitor the quality of the water recharged into the groundwater basin. This includes monitoring of the Santa Ana River surface water and other recharge water supplies. 3.7.1 SANTA ANA RIVER WATER QUALITY Since the quality of the surface water that is used for recharge may affect groundwater quality, a routine monitoring program is maintained to continually assess ambient river water quality conditions. Characterizing the quality of the Santa Ana River and its impact on the basin is necessary to verify the sustainability of continued use of river water for recharge and to safeguard a high-quality drinking water supply for Orange County. On-going surface water monitoring of the Santa Ana River is conducted at Imperial Highway near the diversion of the river to the off-river recharge basins and at a site below Prado Dam. Sampling frequencies for selected river sites and recharge basins are shown in Table 3-3. TABLE 3-3 SURFACE WATER QUALITY SAMPLING FREQUENCY WITHIN ORANGE COUNTY Category SAR Below Dam SAR Imperial Hwy Anaheim Lake Kraemer/ Miller Basin General Minerals M M M Q Nutrients M M M Q Metals Q Q Q Q Microbial M M M M Volatile organic compounds (VOC) M M M Q Semi-volatile organic compounds (SOC) Q Q Q Q Total organic halides (TOX) M M M Radioactivity Q Q Q Q Perchlorate M M M Q Chlorate M M M Q Iodine Q Q NDMA Formation Potential (NDMA-FP) Q Q M = Q = quarterly Note: NDMA-FP and iodine are focused testing initiated in late 2007 and will continue through 2009. Data will be reviewed to determine if monitoring should continue or incorporated into the long-term monitoring program. GROUNDWATER MANAGEMENT PLAN UPDATE 2009 3-15 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING General minerals, nutrients, and selected other constituents are monitored and radioactivity constituents, metals, volatile organics, and semi-volatile organics pesticides and herbicides) are monitored quarterly. Several points on the river and key tributaries to the river above Prado Dam, as shown in Figure 3-12 are also monitored annually for general minerals and nutrients. FIGURE 3-12 OCWD SURFACE WATER MONITORING LOCATIONS ABOVE PRADO DAM 3-16 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING 3.7.1.1 Santa Ana River Water Quality and Health Study In 2004, OCWD completed the Santa Ana River Water Quality and Health (SARWQH) study (OCWD, 2004). This voluntary study was conducted from 1994 to 2004 at a cost of $10 million. The study was initiated due to OCWD’s concerns about the high percentage of treated wastewater discharges into the non-storm flows of the Santa Ana River. The goal of the SARWQH Study was to apply advanced water quality characterization methods to assess the quality of Santa Ana River water and the groundwater after Santa Ana River water is used to recharge the groundwater basin. The multi-disciplinary study design included an examination of hydrogeology, microbiology, inorganic and organic water chemistry, toxicology and public health. The organic water chemistry component included an analysis of trace (low concentration) constituents and dissolved organic compound (DOC) characterization. Analyses and research in the SARWQH Study were conducted by scientists, researchers, and water quality experts from numerous organizations, including Stanford University, Lawrence Livermore National Laboratory, USGS, Oregon State University, and Metropolitan Water District. The results of this extensive study confirmed that current recharge practices using Santa Ana River water are protective of public health. Findings from the SARWQH Study provided information necessary for the planning and permitting of other OCWD projects, such as the GWR System. Results are also helping to shape the CDPH proposed regulations for groundwater recharge. At the request of OCWD, the National Water Research Institute (NWRI) conducted an independent review of the results from the SARWQH Study. NWRI assembled a group of experts in the fields of hydrogeology, water chemistry, microbiology, and the other requisite fields to form the Scientific Advisory Panel. This Panel met annually during the study to review the results and provide recommendations on future work. The panel also prepared a final report (NWRI, 2004) that concluded: “Based on the scientific data collected during the SARWQH Study, the Panel found that: • The SAR met all water-quality standards and guidelines that have been published for inorganic and organic contaminants in drinking water. • No chemicals of wastewater origin were identified at concentrations that are of public health concern in the SAR, in water in the infiltration basins, or in nearby groundwaters. The constituents that were considered included non-regulated chemicals pharmaceutically active chemicals) and contaminants of concern that arose during the course of the SARWQH study n-Nitrosodimethylamine [NDMA]). The unprecedented classification of the major components of DOC and the transformations that occur within these chemical classes as water moves and into the aquifer provided significant new evidence to support the conclusion that the product water is suitable for potable GROUNDWATER MANAGEMENT PLAN UPDATE 2009 3-17 ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING consumption and is also becoming comparable to other sources of drinking water, such as the Colorado River, in its organic profile.” 3.7.2 REPLENISHMENT WATER FROM METROPOLITAN When the District purchases replenishment water from Metropolitan and it is delivered at Anaheim Lake, the water is blended with Santa Ana River water. OCWD samples this blended water for general minerals, nutrients, and other selected constituents. The District may also sample for radioactive constituents, metals, volatile organics, and semi-volatile organics pesticides and herbicides). 3.7.3 GROUNDWATER REPLENISHMENT SYSTEM Recharge water produced by the GWR System is extensively monitored daily, weekly, and quarterly for general minerals, metals, organics, and microbiological constituents as shown in Table 3-4. Focused research-type testing has been conducted on organic contaminants and selected microbial species protozoa, coliphage, etc.) TABLE 3-4 GROUNDWATER REPLENISHMENT SYSTEM PRODUCT WATER QUALITY MONITORING Category Testing Frequency General Minerals M Nitrogen Species (NO3, NO2, NH3, Org-N) and TDS W Metals Q Inorganic chemicals Q Microbial D Total Organic Carbon (TOC) D Non-volatile organic compounds (SOCs) Q Disinfection Byproducts Q Radioactivity Q D = Daily, W = twice weekly, M = Q = quarterly, After the GWR System water is recharged, the water is monitored in the groundwater basin. The District uses an array of monitoring wells in the Talbert Gap and in Anaheim to monitor the water quality. As part of the construction of the GWR System, three new monitoring wells were constructed to complement the District’s existing monitoring wells network. 3.7.4 INTEGRATED GROUNDWATER AND SURFACE WATER MONITORING As part of its recharge water quality monitoring program, the District monitors groundwater quality at selected monitoring wells downgradient of the recharge facilities where the subsurface rate of travel of recharge water is known. These wells provide an indication of groundwater quality as recharge water flows away from the recharge 3-18 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING GROUNDWATER MANAGEMENT PLAN UPDATE 2009 3-19 basins. Recharge water samples are collected in coordination with these targeted groundwater samples so that the changes in water quality with time after recharge can be assessed. This allows for evaluations of water quality for parameters such as nitrate as the water is infiltrated and subsequently flows in the subsurface. This integration of groundwater and surface water monitoring was established based on recharge water tracer studies conducted with water recharge at Anaheim Lake, Kraemer Basin, and the Santa Ana River (Clark et. al, 2004). 3.8 Publication of Data In addition to collecting and managing data in the District’s WRMS as described previously in this section, OCWD analyzes and reports data in a number of regular publications as shown in Table 3-5 below. TABLE 3-5 DATA COLLECTION AND REPORTING Report Frequency of Publication Contents Engineer’s Report on the Groundwater Conditions, Water Supply and Basin Utilization in the Orange County Water District Annual Basin hydrology, groundwater conditions, total groundwater production, groundwater levels, coastal groundwater conditions, calculation of basin accumulated overdraft, supplemental water purchases; required by the District Act Santa Ana River Water Quality Monitoring Report Annual Surface water quality data for the Santa Ana River Groundwater Replenishment System and Talbert Barrier Report Annual Data related to the operation of the Groundwater Replenishment System and the Talbert Seawater Intrusion Barrier; required by permit Santa Ana River Watermaster Report Annual Amounts of Santa Ana River flows at Prado Dam and Riverside Narrows; required by 1969 stipulated judgment Managed Aquifer Recharge Annual beginning 2009 Total amount of managed recharge, recharge data for each recharge basin, sources of and quantities of recharge water supplies ---PAGE BREAK--- SECTION 3 GROUNDWATER MONITORING This page left blank intentionally. 3-20 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-1 4 RECHARGE WATER SUPPLY MANAGEMENT 4.1 Recharge Operations Recharging water into the basin, through natural and artificial means, is essential to support pumping from the basin. Although the amount of recharge and total pumping may not be the same each year, over the long-term the amount of recharge needs to be similar to total pumping. The basin’s primary source of water for groundwater recharge is flow from the Santa Ana River. The Santa Ana River is the largest coastal stream in southern California with a length of 80 miles and a drainage area of 2,470 square miles (Blomquist, 1988). OCWD diverts river flows into recharge basins located in and adjacent to the Santa Ana River and its main Orange County tributary, Santiago Creek. Other sources of recharge water supplies include natural recharge, recycled water, and imported water. OCWD currently operates 1,067 acres of recharge facilities located in and adjacent to the Santa Ana River and Santiago Creek. OCWD recharge facilities are shown in Figure 4-1. Active or managed recharge of groundwater began in 1949, in response to increasing drawdown of the basin and, consequently, the serious threat of seawater intrusion contaminating groundwater. The first imported water used to recharge the basin was Colorado River water purchased from Metropolitan. In 1953, OCWD began making improvements in the Santa Ana River bed and areas adjacent to the river to increase recharge capacity. These improvements included modifying river channels and construction of off-channel recharge basins. Expansion of the recharge system has continued to the present time to the point where nearly all Santa Ana River non-stormflows are captured for recharge into the groundwater basin. Sources of recharge water have expanded to include water from Santiago Creek and purified water from the GWR System. The recharge system consists of a series of recharge basins, also called percolation or spreading basins, whose sidewalls and bottoms allow for percolation into the underlying aquifer. The rate at which water enters from the surface into the ground is the percolation rate (or recharge or infiltration rate). The percolation rate and how it changes through time is the main factor in determining the effectiveness of the recharge facilities. OCWD manages the District’s recharge facilities to maximize groundwater recharge. Efficiently operating existing groundwater recharge basins and facilities and expanding recharge operations where feasible are major District objectives. This section: • Describes the operations of the OCWD recharge facilities; • Explains seawater intrusion barrier operations; and • Discusses the sources of recharge water supplies. ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE FIGURE 4-1 OCWD RECHARGE FACILITIES IN ANAHEIM AND ORANGE ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-3 Higher percolation rates allow a greater quantity of water to infiltrate into the groundwater basin. Percolation rates tend to decrease with time as the percolation basins develop a thin clogging layer on the basin bottom. The clogging layer develops from fine grain sediment deposition and from biological growth. Percolation rates are restored by mechanical removal of the clogging layer from the basins. Mechanical removal methods that are employed utilize heavy equipment such as dozers, scrapers, and other equipment. Additionally, basin cleaning vehicles are employed in selected basins. These basin cleaning vehicles operate while the basin is in operation. 4.1.1 Prado Basin The majority of water recharging the basin is Santa Ana River water that enters Orange County after flowing through the Prado Dam. The dam, shown in Figure 4-2, was built by the U.S. Army Corps of Engineers (ACOE) in 1941 “for flood control and other purposes.” FIGURE 4-2 PRADO DAM AND OCWD PRADO WETLANDS ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT In the 1960s the ACOE began working with OCWD to conserve base and stormflows behind the dam in order to enable OCWD to divert flows into recharge facilities. In 1994, the ACOE adopted new dam operating procedures to increase water conservation (ACOE, 1994). During non-storm periods, the ACOE now releases water stored behind Prado Dam at rates compatible with OCWD’s recharge capacity as long as the stored water does not compromise the use of the dam for flood control purposes. Although the District’s recharge system has the capacity to capture all Santa Ana River baseflows released through the Prado Dam, stormflows occasionally exceed the diversion capacity. OCWD continuously works with the ACOE to manage flow rates in order to maximize the recharge of stormflows. A new Memorandum of Agreement between OCWD and the ACOE, executed in 2006, authorized a four-foot increase in the maximum winter pool elevation. Water now can be stored temporarily behind Prado Dam up to an elevation of 498 feet mean sea level during the flood season, and up to an elevation of 505 feet during the non-flood season, as shown in Figure 4.3. FIGURE 4-3 MAXIMUM CONSERVATION STORAGE ELEVATIONS ALLOWED BEHIND PRADO DAM 4.1.2 Recharge Facilities in Anaheim and Orange The District operates 30 recharge facilities in the Cities of Anaheim and Orange and unincorporated areas of Orange County. These facilities, listed in Table 4-1, have a combined total storage volume of approximately 26,000 af. For descriptive purposes, they are grouped into four major components: the Main River System, the Off-River System, the Deep Basin System, and the Burris Basin/Santiago System. 4-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-5 TABLE 4-1 AREA AND STORAGE CAPACITIES OF RECHARGE FACILITIES Notes: 1. Maximum (Max.) storage capacity is typically not achieved for most facilities due to need to reserve buffer space for system flow and level fluctuations. 2. Owned by Orange County Flood Control District (OCFCD). Max. storage capacity shown is maximum flood control storage. 3. Various owners, including OCFCD, City of Orange, and Metropolitan. Facility Wetted Area Max. Storage Capacity (acres) (af) Anaheim Lake 72 2,260 Burris Basin 120 2,670 Conrock Basin 25 1,070 Five Coves Basin: Lower 16 182 Five Coves Basin: Upper 15 164 Foster-Huckleberry Basin 21 630 Kraemer Basin 31 1,170 La Jolla Basin 6.5 26 Lincoln Basin 10 60 Little W arner Basin 11 225 Miller Basin 25 300 Mini-Anaheim Lake 5 13 Off-River Channel: Olive Basin-Carbon Creek Diversion 42 N/A Off-River Channel: Weir Pond 4-Olive Basin 47 N/A Olive Basin 5.8 122 Placentia Basin 9 350 Raymond Basin 19 370 River View Basin 3.6 11 Santa Ana River: Ball Road - Orangewood Ave. 59 N/A Santa Ana River: Five Coves Dam-Ball Road 74 N/A Santa Ana River: Imperial Hwy -Five Coves Dam 158 N/A Santiago Basins: Bond Basin 86 8,380 Santiago Basins: Blue Diamond Basin 79 5,020 Santiago Basins: Smith Basin 22 320 Santiago Creek: Santiago Basins -Hart Park 2.6 N/A W arner Basin 70 2,620 W eir Pond 1 6 28 W eir Pond 2 9 42 W eir Pond 3 14 160 W eir Pond 4 4 22 Totals 1,067 26,215 ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4.1.2.1 Main River System Water released at the Prado Dam naturally flows and percolates through the river’s 300-400 foot wide unlined channel bottom that consists of sandy, permeable sediment. The Main River System consists of approximately 291 acres along a six-mile reach of the Santa Ana River Channel, just west of Imperial Highway to Orangewood Avenue. of Orangewood Avenue shallow, low-permeability clay layers reduce the ability to recharge river water. The upstream portion of the Main River System begins at the Imperial Inflatable Dam. The Imperial Inflatable Dam and Bypass Structure is one of the District’s key control structures. It allows the District to divert Santa Ana River water from the Main River System into the Off-River System. The Imperial Inflatable Dam, installed in 1993, is seven feet in diameter and 300 feet long, as shown in Figure 4-4. It is constructed of rubberized fabric that is inflated with air. When the stormflow rate exceeds approximately 1,500 cubic feet per second (cfs), the dam is deflated and only minimal water can be diverted for recharge. During some flow conditions, from 1,000-2,000 cfs, the dam is partially inflated, allowing some diversion for recharge and the remainder of the water to flow over the dam. FIGURE 4-4 INFLATABLE DAM ON THE SANTA ANA RIVER The pooled water behind the inflated dam flows through the bypass structure on the north side of the river. The bypass structure includes a series of steel gates leading to conduits that divert up to 550 cfs of water into the Off-River System. Water passes through trash racks to keep debris out and then flows into Weir Pond 1. OCWD maximizes recharge in the Main River System by bulldozing a series of sand levees in the river, as shown in Figure 4-5. These levees allow greater percolation by increasing the residence time of water in the permeable section of the river and by spreading the water across the width of the river to maximize the wetted surface area. Typically, water flows at a velocity sufficient to prevent the accumulation of fine sediment and biological growth. The riverbed is also cleaned naturally, when winter and spring stormflows wash out the levees and scour the bottom. When necessary, heavy equipment is used to move sediments in order to restore the high percolation rate. Sand levees remain intact until flows exceed approximately 350 cfs, at which time they erode and water flows from bank to bank in the riverbed. Although percolation is believed to remain high during these high flow conditions, rates are difficult to measure. 4-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-7 FIGURE 4-5 SAND LEVEES IN THE SANTA ANA RIVER 4.1.2.2 Off-River System The Imperial Inflatable Dam and Bypass Structure diverts Santa Ana River water flows from the Main River System into the Off-River System. This system includes four ponds called ‘Weir Ponds’ and a channel called the ‘Off-River recharge basin’. Weir Ponds 1, 2, 3, and 4 are used to remove sediment from the Santa Ana River water diverted at the Imperial Inflatable Dam. The Weir Ponds have a surface storage of approximately 200 acre-feet. At the most Weir Pond, Weir Pond 4, water can flow into the Off-River Recharge Basin, the Huckleberry Basin, or the Warner Bypass Pipeline. The Off-River Recharge Basin consists of a shallow, sandy bottom, 200-foot wide channel that runs parallel to the Main River System for approximately 2.3 miles from the Imperial Inflatable Dam down to the Carbon Creek Diversion Channel. The Off-River Recharge Basin is separated from the Main River System by a levee. Water in the Off-River Recharge Basin can be diverted into Olive Basin, which is located near Tustin Avenue. 4.1.2.3 Deep Basin System The Deep Basin System consists of the Warner Basin Sub-system (Foster-Huckleberry, Conrock , Warner, and Little Warner Basins), along with Anaheim Lake, Mini Anaheim, and Miller, Kraemer, La Jolla, Placentia, and Raymond Basins. Up to 400 cfs of water can be diverted into Foster-Huckleberry and then into Conrock and Warner Basins. These recharge basins range in depth from 10 to 60 feet. Portions of their side-walls and bottoms are composed of natural, sandy, permeable materials that allow water to percolate into the aquifer. Percolation rates vary depending on the size and depths of the basins; rates slow significantly as fine-grained sediment particles accumulate on the basin bottoms. Most of the basins in this system can be drained and cleaned with equipment, shown in Figure 4-6, to remove this clogging layer, thereby restoring percolation rates and increasing recharge efficiency. The Santa Ana River bed percolation rate has been declining by approximately one percent per year for the last 20 years due to the coarsening of the river bed that is a common problem in river beds of dams. This occurs because sand that would naturally flow down the river is trapped behind Prado Dam. The reduction in the amount of sand in the river bed causes sediments to become less conducive to percolation, particularly in the area closest to Imperial Highway. ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-8 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE FIGURE 4-6 CLEANING OF RECHARGE BASINS When the Warner Basin Sub-system is full, flows into the system are reduced to approximately 250 cfs. This maximizes percolation and allows the remainder of the water to be piped to the other basins (Anaheim Lake, Mini Anaheim Lake, Miller, Kraemer, La Jolla, Placentia, and Raymond). Placentia and Raymond basins are owned by Orange County Public Works and can only be used during the non-flood season. Water is conveyed to these two basins using the Carbon Creek Channel. The Five Coves Inflatable Dam is located on the Santa Ana River approximately three miles of the Imperial Inflatable Dam. It was installed by OCWD in 1994 to divert flows into Five Coves, Lincoln, and Burris Basins. The dam is essentially the same size and construction as Imperial Inflatable Dam. Excess flows above 100 cfs and less than 500 cfs can be diverted at the dam; during storm events, flows over 500 cfs are lost to the ocean beyond this dam. 4.1.2.4 Burris Basin/Santiago System The Burris Basin/Santiago System consists of 354 acres of shallow and deep recharge basins. The system begins at the confluence of the Santa Ana River and the Carbon Canyon Diversion Channel and ends at the Santiago Basins in Orange. It consists of Upper Five Coves, Lower Five Coves, Lincoln, Burris (shown in Figure 4-7) and River View Basins, the Santiago Basins (Blue Diamond Basin, Bond Basin, and Smith Basin), and Santiago Creek five miles east of the river. The Five Coves Inflatable Rubber Dam diverts up to 500 cfs of flow from the Santa Ana River into Upper Five Coves Basin. This water can then flow sequentially into Lower ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT Five Coves Basin, Lincoln Basin, and Burris Basin. From there, the Burris Basin Pump Station can pump up to 230 cfs of water through the 66-inch diameter Santiago Pipeline to the Santiago Basins and Santiago Creek. Once Burris and the Santiago Basins are full, the flow must be reduced to match the Santiago Basins’ percolation rate of approximately 125 cfs. FIGURE 4-7 BURRIS BASIN Santiago Creek, a tributary to the Santa Ana River, shown in Figure 4-8, is the primary drainage for the northwest portion of the Santa Ana Mountains. The creek extends from the mountains, through the City of Orange to its confluence with the Santa Ana River in the City of Santa Ana. Two dams along the river impound flows. Santiago Dam, which creates Irvine Lake, is owned by the Irvine Ranch and Serrano Water Districts. Villa Park Dam is primarily a flood control dam owned and operated by the Orange County Flood Control District. OCWD’s Santiago Basins are located of Villa Park Dam. Here Santiago Creek flows are supplemented by water diverted from the Santa Ana River through the Santiago Pipeline. These former gravel pits recharge up to approximately 125 cfs when full. When the Santiago Basins are full, overflow from the basins flows down the sandy and rocky Santiago Creek bed. Natural percolation through the creek bottom into the groundwater basin occurs until water reaches Hart Park in the City of Orange. The Santiago Basin Pump Station, completed in 2003, provides greater flexibility in managing recharge operations. Pumps placed in the bottom of Bond Basin move water out of the Santiago Basin into Santiago Creek or back down into the Santiago Pipeline where water can be discharged to the River View Basin or back to Burris Basin. River View Basin is located on the east side of the Santa Ana River adjacent to Burris Basin. Pumping water to and from the Santiago Basins increases the quantity of groundwater recharge and creates capacity in the Santiago Basins for storage of water from winter storms. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-9 ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-10 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE FIGURE 4-8 SANTIAGO CREEK STORAGE AND RECHARGE AREAS ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-11 4.2 Sources of Recharge Water Water supplies used to recharge the groundwater basin are listed in Table 4-2. TABLE 4-2 SOURCES OF RECHARGE WATER SUPPLIES Water Supply Source of Recharge Water Supply Recharge location Baseflow Perennial flows from the upper watershed in Santa Ana River; predominately treated wastewater discharges OCWD recharge basins and the Santa Ana River Santa Ana River Stormflow Precipitation from upper watershed flowing in Santa Ana River through Prado Dam OCWD recharge basins and the Santa Ana River Santiago Creek Santiago Creek OCWD recharge basins; natural percolation in Santiago Creek Natural Recharge Precipitation and flows from Orange County foothills Throughout the basin Groundwater Replenishment System GWR System treatment facility Injected into Talbert Barrier; Kraemer and Miller basins Purified Water Water Replenishment District of Southern CA Water purified at the Leo J. Vander Lans Treatment Facility Injected into Alamitos Barrier Metropolitan Water (untreated) State Water Project and Colorado River Water Various recharge basins Metropolitan Water (treated) State Water Project and Colorado River Water through the Diemer Water Treatment Plant Injected into Talbert and Alamitos Barriers Arlington Desalter Purified water from Arlington Desalter released to Santa Ana River above Prado Dam OCWD recharge basins San Bernardino Valley Municipal Water District Surplus groundwater released into the Santa Ana River in San Bernardino OCWD recharge basins Imported Water and Supplemental Water Western Municipal Water Surplus groundwater released into the Santa Ana River in Riverside Released into the Santa Ana River above Prado Dam to OCWD recharge basins In Lieu Replenishment Water Metropolitan Water District of Southern California Treated imported water used to replace pumping of groundwater, when available Water is delivered directly to Producers ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4.2.1 Santa Ana River The primary source of water amount of the baseflow water, especially tertiary-treated wastewater di Prado Dam. OCWD has legal rights to a minimum of 42, minimum amount of Santa Ana River bas entered into by OCWD and ups commonly referred to as From the 1970s to the mid-1990s approximately 50,000 afy to 15 increases in the area above Pra discharges Santa Ana River at Prado Dam for the peri FIGURE 4-9 SANTA ANA RIVER FLOWS AT PRADO DAM Source: Santa Ana River Watermaster 2009 Thousands of Acre-Feet to recharge the basin is Santa Ana River flows. A large in the summer months, is composed of scharges from wastewater treatment facilities upstream of 000 afy of Santa Ana River baseflow. The eflow was established in a legal agreement tream water agencies in 1969. This agreement is the ‘1969 Judgment.’ , the rate of Santa Ana River baseflow increased from 0,000 afy. This is attributed primarily to population do Dam, which resulted in additional treated wastewater from upstream communities. Figure 4-9 illustrates historic baseflow in the od from water year 1934-35 to 2006-07. 4-12 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 0 100 200 300 400 500 600 L WATER YEAR EGEND STORM FLOW BASE FLOW 1934-35 1939-40 1944-45 1949-50 1954-55 1959-60 1964-65 1969-70 1974-75 1979-80 1984-85 1989-90 1994-95 1999-00 2004-05 2009-10 ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-13 In December 2008, the State Water Resources Control Board approved the issuance of a permit to OCWD to appropriate 362,000 afy from the Santa Ana River. The also agreed to hold an additional 143,000 afy in abeyance for OCWD for possible future projects. This provides an opportunity for OCWD to pursue long-term projects and complete environmental analysis and planning of those projects by 2023. Provided that this is completed by 2023, OCWD can seek the additional rights without the need to restart the water rights application process. The volume of water recharged into the basin from Santa Ana River stormflows changes yearly due to variations in the amount of precipitation and the timing of precipitation and stormflow. Although stormflows average approximately thirty- three percent of the total Santa Ana River flows, only approximately half of that amount is recharged at OCWD's spreading facilities. This is primarily because the magnitude of stormflow releases from Prado Dam often greatly exceeds the District’s diversion and recharge capacity. While the estimated maximum percolation capacity of the recharge basins is 500 cfs, the rate of Santa Ana River stormflow can reach up to 3,000 cfs or more, roughly six times the recharge capacity. The volume of water lost to the ocean can reach 5,000 af/day or more. Although it is common to have some loss to the ocean every year, during wet years losses can be great; in water year 1997-98, the District lost approximately 270,000 af of Santa Ana River stormflows to the ocean. Figure 4-10 shows the precipitation at San Bernardino, indicating the variation of precipitation from year to year. FIGURE 4-10 PRECIPITATION AT SAN BERNARDINO Precipitation (inches) Water Year (Oct-Sep) p 0 10 20 30 40 50 -20 0 20 40 60 80 1950-51 1952-53 1954-55 1956-57 1958-59 1960-61 1962-63 1964-65 1966-67 1968-69 1970-71 1972-73 1974-75 1976-77 1978-79 1980-81 1982-83 1984-85 1986-87 1988-89 1990-91 1992-93 1994-95 1996-97 1998-99 2000-01 2002-03 2004-05 2006-07 2008-09 1934-35 1936-37 1938-39 1940-41 1942-43 1944-45 1946-47 1948-49 Annual Precipitation Average Precipitation Accumulated Departure From Average Accumulated Departure from Average (inches) ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-14 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Figure 4-11 shows the amount of Santa Ana River stormflow recharged by the District for the past eighteen years. Based on the data in this figure, an average of 50,000 afy of stormflow has been captured and recharged. Precipitation in the form of snow accumulating in the upper watershed’s mountains usually allows for greater recharge as snow melting over time provides a steady baseflow for recharge. Maximizing the capacity to store stormwater at Prado Dam for groundwater recharge also aids OCWD’s efforts to maintain good water quality. Stormwater usually has lower total dissolved solids and nitrate concentrations than Santa Ana River baseflow, so blending stormwater with other sources of recharge water improves water quality. FIGURE 4-11 STORMFLOW RECHARGED IN THE BASIN 4.2.2 Santiago Creek Most of the natural flow of Santiago Creek is captured behind the impoundments described earlier. Water released into the creek flows and recharges into the groundwater basin. Since 2000, OCWD has operated the Santiago Creek Recharge Project. A permit from the (permit 19325) allows OCWD to collect and store up to 33,560 afy from Santiago Creek. Using controlled releases into the creek, up to approximately 15 cfs is recharged between the Santiago Basins and Hart Park in the City of Orange. In 2008, OCWD completed a project to grade the channel to smooth out the channel bottom. Over time the creek flows became confined to a relatively small notch in the channel. Removing this low-flow channel allowed water to spread out and cover a larger surface area, which increased the recharge rate. In 2008-09, three monitoring wells were constructed to assess recharge conditions and water quality along Santiago Creek and the Santiago Basins. These wells will provide important information regarding recharge from the creek and the Santiago Basins. Thousands of Acre-feet Water Year 0 40 80 [PHONE REDACTED]-91 1991-92 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-15 4.2.2.1 Natural Recharge Natural infiltration of recharge, also referred to as incidental recharge, occurs from subsurface inflow from the local hills and mountains, infiltration of precipitation and irrigation water, unmeasured recharge from small flood control channels, and groundwater underflow to and from Los Angeles County and the ocean. Natural incidental recharge occurs outside the District’s control. Net incidental recharge refers to the net amount of incidental recharge that occurs after accounting for subsurface outflow to Los Angeles County. As described in Section 2, an increase in the accumulated overdraft in the basin decreases the estimated amount of outflow to Los Angeles County. Estimated net incidental recharge and precipitation in Anaheim is shown in Figure 4-12. On average, approximately 60,000 very wet years such 100,000 afy or more. The increase of impe industrial, commercial, and residential dev channels that drain to the oc development with the emphasis removal of stormwater. Concer water quality impacts from landscape irrigat interest in low-impac runoff. Utilization of LID, such a systems can lead to an increase the rate of inci however, could hav adversely impact the basin’s water quality. FIGURE 4-12 NET INCIDENTAL RECHARGE af of net incidental recharge occurs each year. In as 2004-2005, the amount of incidental recharge can be rmeable surfaces reduces the amount of natural infiltration. New elopments may divert storm flows into ean instead of percolating into the ground. Decades of on flood protection have encouraged rapid, efficient ns about the reduction in natural recharge as well as ion runoff and storm flow have increased t development (LID), the on-site capture and management of s dry-wells, swales, wetlands, and other engineered dental recharge. Increasing infiltration, e negative impacts if percolation of poor quality water would Water Year 0 50 100 150 200 0 10 20 30 40 Precipitation in Anaheim Natural Incidental Recharge 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 Incidental Recharge (1,000 AF) Precipitation (inches) ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4.2.3 Purified Water OCWD has source for the Talbert Talbert seawater intrusion barrier. 4.2.3.1 Groundwa The GWR System is a joint project of OC a new sour groundwater supplies. 72,000 three major components: stations, a pipeline connec FIGURE 4-13 GROUNDWATER REPLENISHMENT SYSTEM MAP been purifying wastewater to recharge the basin since 1975. Water Factory- 21 (WF-21), in operation from 1975 to 2004, purified treated wastewater to provide a Barrier. In 2008, the GWR System replaced WF-21 and began operation to provide water for groundwater recharge in Anaheim as well as for the ter Replenishment System WD and the OCSD. The GWR System creates ce of recharge water that will increase the reliability and sustainability of local The GWR System augments existing groundwater supplies by producing up to afy of purified water to recharge the basin and provide a reliable supply of water for the Talbert Seawater Barrier. As shown in Figure 4-13, the GWR System consists of Advanced Water Treatment (AWT) facilities and pumping tion from the treatment facilities to existing recharge basins, and expansion of the Talbert Barrier. 4-16 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-17 Secondary-treated effluent from the OCSD Wastewater Reclamation Plant No. 1 in Fountain Valley is pumped to the AWT facilities instead of to the ocean for disposal. The advanced water purification plant purifies the water with microfiltration (MF); reverse osmosis (RO); and advanced oxidation processes (AOP), which consist of ultraviolet (UV) and hydrogen peroxide (H2O2). The first step in the tertiary treatment process is MF membrane treatment. MF is a low- pressure membrane process that removes small suspended particles, protozoa, bacteria and some viruses from the water. Sodium hypochlorite, a bleach solution, is added to the MF feedwater to minimize MF membrane fouling. Next, the MF filtrate is fed to the RO treatment system. Dissolved contaminants and minerals, including dissolved organics, total dissolved solids, silica, and virus, are removed in the RO treatment process. The water then undergoes UV and H2O2 treatments. UV light penetrates the cell walls of microorganisms, preventing replication and inducing cell death. This provides an additional barrier of protection against bacteria and viruses. More importantly, UV with H2O2 oxidizes organic compounds. At this point, the product water is so pure that it can not be moved in conventional pipes. Small amounts of minerals are added back into the water so that it is stable in the concrete pipes. Although the GWR System is capable of producing 72,000 afy of water, the first year of operation actually produced less than 45,000 af of water. Operation of the system is limited by the supply of secondary-treated wastewater from OCSD. OCSD is in the process of constructing a pump station, scheduled to be completed before the end of 2009, which will help provide additional flow into the GWR System. When the pump station becomes operational, District staff expects to operate the GWR System to full capacity. In addition, OCSD anticipates that construction of an expansion to their secondary treatment processes will be complete in late 2011. With this increase of available supply of wastewater, OCWD plans to expand the GWR System. The initial expansion will be designed to increase production by 17,000 to 20,000 afy of water. 4.2.3.2 Talbert and Alamitos Barriers The GWR System is the primary source of water used for injection at the Talbert Barrier. An additional source of water for the barrier is treated potable water purchased from Metropolitan. Water for the Alamitos Barrier is supplied from two sources: imported water from Metropolitan and purified wastewater purchased from the Water Replenishment District of Southern California (WRD) under a joint cost sharing agreement with OCWD, as explained in Section 4.2.4.2. 4.2.4 Imported Water Water purchased by OCWD for recharge comes from a number of sources. This recharge water is also referred to as replenishment water, supplemental water or imported water. Total annual recharge of imported water from 1937 to 2008 is shown in Figure 4-14. ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-18 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Metropolitan provides untreated replenishment water to the District when excess supplies are available. These supplemental supplies are an unreliable source of recharge water as they are typically unavailable to purchase during droughts. OCWD receives State Water Project (SWP) water from Northern California at a number of locations. Water released through a connection in Claremont flows down San Antonio Wash to Chino Creek, which drains into the Santa Ana River. Colorado River water can be delivered via the Santa Ana River upstream of OCWD’s main recharge basins. A blend of SWP water and Colorado River waters can also be received directly into Anaheim Lake. The District typically has recharge capacity available to receive this water during the summer/fall months. However, these supplies by nature are more frequently available during the winter season, which is when the District’s recharge facilities are being used to capture and recharge Santa Ana River flows. The District can usually take between 50 cfs to 200 cfs (100 - 400 af/day) of direct replenishment water depending upon the operating condition of the recharge facilities. FIGURE 4-14 ANNUAL RECHARGE OF IMPORTED WATER FROM METROPOLITAN, 1950-2008 4.2.4.1 Upper Watershed Imported Water OCWD has historically entered into agreement with water agencies in the upper watershed to pay for excess upper watershed water that the agencies pump into the Santa Ana River that reaches Prado Dam. This water is captured for recharge in the OCWD facilities. The sources listed here are only available when the supplying water 0 50 100 150 [PHONE REDACTED] 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Water Year (Jul-Jun) Total Annual Recharge (1,000 AF) State Project Water Colorado River Water ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-19 agency has excess supplies. During times of drought, these sources become less available. • The Arlington Desalter. When potable consumption does not match the output of the Arlington Desalter in Riverside, the District may purchase the excess water for groundwater recharge. • The Bunker Hill Basin groundwater pump out project in San Bernardino is a cooperative project with the San Bernardino Valley Municipal Water District. The project was constructed to mitigate the negative impacts of high groundwater levels. Groundwater is pumped from the Bunker Hill Basin into the Santa Ana River. • Western Municipal Water District provides to OCWD up to 7,000 afy of recharge water when available. This water is discharged into the Santa Ana River and is recharged into the groundwater basin in the District’s recharge system. 4.2.4.2 Alamitos Seawater Intrusion Barrier Source Water The WRD manages groundwater for nearly four million residents in 43 cities of southern Los Angeles County. The City of Long Beach, under contract with WRD, operates the Leo J. Vander Lans Treatment Facility, an advanced water treatment facility that treats effluent water from the Sanitation District of Los Angeles County using MF, RO, and UV treatment. About 2.7 million gallons of purified water are blended with imported water and pumped into the Alamitos Seawater Barrier. 4.2.4.3 In Lieu Replenishment Water When recharge capacity is unavailable, OCWD can also receive replenishment water via an In-lieu program. In-lieu recharge refers to the practice of increasing groundwater storage by providing interruptible potable water supplies to a user who relies on groundwater as a primary supply. This treated potable water is made available to Producers who, in turn, use the supply in place of pumping an equal supply of groundwater. This program is revenue neutral for Producers and helps recharge the groundwater basin in a targeted manner. 4.3 Recharge Studies and Evaluations The District has an ongoing program to assess enhancements in existing recharge facilities, evaluate new recharge methods, and analyze potential new recharge facilities. 4.3.1 OCWD RECHARGE ENHANCEMENT WORKING GROUP (REWG) The REWG is composed of staff from several departments that works to maximize the efficiency of existing recharge facilities and evaluate new concepts to increase recharge capacity. REWG, with staff from recharge operations, hydrogeology, engineering, research and development, regulatory affairs, and the planning departments, meets on a regular basis to review new data and evaluate potential new projects. ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-20 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Proposed projects, such as reconfiguration of existing basins, operational improvements to increase flexibility in the management of the basins, alternative basin cleaning methods, potential sites for new basins, and control of sediment concentrations, are discussed and prioritized. 4.3.2 COMPUTER MODEL OF RECHARGE FACILITIES OCWD is in the process of developing a computer model of the District’s recharge system in Anaheim and Orange. The model will simulate Prado Dam operations, Santa Ana River flow, and each recharge facility in order to model how the recharge system operates in conjunction with storage of water behind Prado Dam and flows from the Santa Ana River. This planning tool will be used to evaluate various conditions including estimating recharge benefits if new recharge facilities are constructed, existing facilities are improved, increased storage is achieved at Prado Dam, or baseflow changes occur in the Santa Ana River. Output from the model will include: • Amount of water in storage at Prado Dam and storage and recharge rates at each recharge facility; • Amount of water that could not be recharged and the frequency of water loss to the ocean; • Optimal amount of cleaning operations; and • Available (unused) recharge capacity. The model will be constructed so that it can be operated by District staff from a desktop personal computer using a graphical user interface. 4.4 Improvements to Recharge Facilities The District regularly evaluates potential projects to improve the existing recharge facilities and build new facilities. Changes to existing facilities may include: • improving the ability to transfer water from one recharge basin to another; • improving the ability to remove the clogging layer that forms on the bottom of the recharge basins; • removing shallow low-permeability silt or clay layers that occur beneath recharge basins • improving the shape or configuration of the basin to increase the infiltration rate or ability to clean the basin; and • converting an existing underperforming recharge basin to a new type of recharge facility. The District also regularly evaluates building new facilities. This effort includes: • evaluating existing flood control facilities that could be utilized to increase recharge; ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-21 • evaluating potential sites for purchase and subsequent construction of new recharge facilities; and • evaluating potential dual-use sites, where a subsurface recharge system could be built and remain compatible with the existing use, such as building a subsurface infiltration gallery under a parking lot. 4.4.1 RECHARGE FACILITIES IMPROVEMENTS 2004-2008 The following projects were completed between 2004 and 2008 by OCWD to improve recharge operations: La Jolla Basin OCWD purchased land along Carbon Creek east of Placentia Basin and west of Kraemer Basin and constructed a new 6-acre recharge basin. Water is diverted from Carbon Creek using a rubber dam. The six-foot deep basin can be easily drained by gravity flow back to Carbon Creek when necessary for maintenance. The basin was placed on line in 2008 and is expected to recharge as much as 9,000 afy. Olive Basin Intake Structure Improvements Prior to acquisition by OCWD, the Olive Basin was mined for sand and gravel. A corrugated metal transfer tube was installed to convey Santa Ana River water into the basin. However, this transfer tube was located mid-way up the side of the basin and the flow discharging into the basin eroded the sidewalls, causing sediment to rapidly clog the basin. Improvements that were completed in 2007 included the installation of a new transfer pipe and concrete box set at the bottom of the basin to allow water to flow into the basin from the bottom. Mini-Anaheim Recharge Basin Modifications Improvements to this small basin made in 2005 increased the efficiency of moving Santa Ana River water into the basin. A new pipeline also was constructed to allow discharge of imported water directly into the basin. Kraemer-Miller Basins Pipeline Improvements An existing 48-inch pipe in Kraemer Basin was replaced due to the potential for pipe failure that would have resulted in damage to adjacent property and a reduction in recharge capacity from loss of ability to fill the basin. An inlet pipe was installed in Miller basin. Lincoln-Burris Exploratory Wells Monitoring wells were constructed to characterize the ability of the natural sediments along the west walls of Lincoln and Burris Basins to percolate water. Data collected were used to support a feasibility study of re-contouring the Burris Basin to allow periodic cleaning of the western side wall in order to increase percolation rates. ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-22 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Warner Basin Dam In order to clean Warner Basin, staff would construct an earthen dike to allow the draining of the basin while simultaneously transferring water to Anaheim Lake, Miller Basin, and Kraemer Basin. In 2007, a rubber dam was installed within the finger channel of the Little Warner Basin to eliminate the need to build the earthen dike each time the basin needed cleaning. Santiago Creek Recharge Enhancement The recharge capacity of Santiago Creek was increased by grading the creek bed upstream of Hart Park in the City of Orange. Prior to grading, a low-flow channel developed in the channel bottom. Water flow was confined to this low- flow channel, limiting the amount of groundwater recharge. The grading project completed in 2008 created a flat cross-section allowing for flows to spread out over a larger surface area, thereby increasing groundwater recharge. 4.5 Potential Projects to Expand Recharge Operations The District’s Long-Term Facilities Plan (2009) contains a list of potential new projects to expand recharge operations. Projects that are included range from those in the conceptual phase to those in the process of construction to improve operations of recharge facilities and to increase the amount of water recharged into the groundwater basin are described in this section. Desilting Improvement Program The build up of sediment in recharge basins decreases infiltration rates and increases the need for basin cleanings. Approaches are being evaluated to remove sediment from Santa Ana River water in order to increase the performance of current recharge facilities. A feasibility study identified proposed treatment systems for pilot testing. Mid-Basin Injection As the GWR System is expanded an increased supply of recharge water will be available. In order to recharge this supply of water, a mid-basin injection project is being considered. This would involve using high quality GWR System water for direct injection into the Principal aquifer in the central portions of the Basin. By directly injecting water into the Principal aquifer where most of the pumping occurs, low groundwater levels due to pumping can be reduced. Also, mid-basin injection would reduce the recharge requirement in Anaheim and Orange area recharge basins, thus providing more capacity to recharge Santa Ana River water. Santiago Creek Enhanced Recharge Two improvements to Santiago Creek in the City of Orange are being considered to enhance recharge capacity. One project consists of cutting a water conveyance channel through a concrete-lined creek channel to deliver a flow of water of Hart Park. The geology in this lower stretch of the creek is being studied to determine if the recharge would be beneficial to the groundwater ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 4-23 basin. The second project would investigate the feasibility of constructing three small new recharge basins adjacent to Santiago Creek. Subsurface Recharge The subsurface recharge project would involve constructing horizontal recharge systems beneath areas with existing improvements, such as parks or school athletic fields. These infiltration galleries would allow percolation of recharge water through perforated pipes buried in gravel-filled trenches. Since there is no feasible way to clean the galleries, the source water would come from the GWR System, treated Metropolitan water, or filtered Santa Ana River water. Recharge Basin Rehabilitation All of the recharge basins are subject to clogging due to the accumulation of sediments contained in recharge water. To maintain recharge rates, the basins are periodically drained, allowed to dry, and then mechanically cleaned using heavy equipment. This process removes most of the clogging layer but also removes a portion of the underlying layer of clean sand from the basin bottom. Some of the fine-grained clogging material on the basin sides remains while the bottom of the basin progressively deepens. Although cleaning procedures have been improved to minimize the burial of fine-grained clogging material, previous cleaning practices have left an irregular mantle of fine-grained material in the upper one to two feet of some recharge basins. This may be remedied by over- excavating and replacing removed sediments with clean sand. Burris and Lincoln Basins Reconfiguration Modifications to Burris and Lincoln Basins will improve recharge capability. Plans include excavating low-permeability sediments from Lincoln Basin and the northern end of Burris Basin, reconfiguring the conveyance of water into Burris Basin, and expanding the size of Lincoln Basin. Also, a pilot transfer well will be drilled to transfer groundwater from the Shallow Aquifer to the Principal Aquifer at the southern end of Burris Basin. Five Coves and Lincoln Basins Bypass Pipeline Santa Ana River flows are diverted into the Upper Five Coves Basin by an inflatable dam. Transfer pipes convey surface flows from the Upper Five Coves to the Lower Five Coves Basin. Construction of a pipeline within the Lower and Upper Five Coves, Lincoln, and Burris basins would allow water transfers between the four basins. This would allow the Upper Five Coves, Lower Five Coves, and Lincoln Basins to be isolated and taken out of service to conduct cleaning operations, while maintaining flow of water to Burris and Santiago Basins. In the current system, inflow to Burris Basin has to be terminated to allow cleaning of the other four basins. Santiago Basins Pump Station A pump station was constructed to dewater the Santiago Basins to increase storm flow capture and percolation, to make storage available for winter season use, to provide water to the Santiago Creek for percolation, and to increase ---PAGE BREAK--- SECTION 4 RECHARGE WATER SUPPLY MANAGEMENT 4-24 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE operational flexibility by pumping water back to Burris Basin when necessary. Two of the four installed pumps failed to operate so the pump station needs to be redesigned and rebuilt. Reconstructing a pump station for the basins will increase recharge capacity and allow for more flexible and efficient operations. Placentia and Raymond Basins Improvements Improvements to Placentia and Raymond Basins that would increase the amount of water recharged in these basins include construction of in-channel diversion structures, modification of inlets to increase flows, installation of submersible pumps, and addition of flow measuring devices, water level sensors, and equipment to remotely control and record water levels and flows. Santiago Basins Intertie Constructing a connection between the Bond and Blue Diamond Basins would allow greater flexibility in managing recharge water. Conveyance of water from Blue Diamond Basin to Bond Basin is limited by a dirt berm that separates the two basins. This berm traps approximately 1,500 af of water in Blue Diamond Basin. Improvement would involve either removing a portion of the dirt berm or installing a pipe within the berm between the two basins at the bottom elevation of Blue Diamond Basin. Olive Basin Pump Station Improvements to Olive Basin will allow the basin to be drained more rapidly for cleaning. Olive Basin does not have a dewatering pump. An intake structure with a 36-inch diameter fill pipe was constructed to allow water to flow from the Off-River System into the deepest part of the pit. This decreased the amount of sediment stirred up in the basin, thereby increasing the recharge performance. Installation of a pump station and drain pipe will allow for future draining of the basin so that the basin can be cleaned quickly and restored to service. Prado-Recharge Facilities Model This project would create a mathematical model of Prado storage, Santa Ana River flow, and each recharge facility. The model would simulate how the recharge system operates in conjunction with Prado storage and the river. It is anticipated that the model would have a time step of one day. The model would allow the evaluation of changes in recharge that would occur if the District were to construct improvements to existing facilities, build new recharge facilities, or achieve increased levels of storage at Prado Dam. ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT 5 WATER QUALITY MANAGEMENT Water quality protection is a basic tenet of OCWD. The District manages the groundwater basin to protect water quality. This section describes the range of programs conducted by OCWD throughout the watershed including: ƒ Implementing OCWD’s Groundwater Protection Policy; ƒ Participating in water quality management programs in the watershed; ƒ Managing levels of salinity and nitrate; ƒ Restoring contaminated water supplies; ƒ Developing programs to monitor constituents of emerging concern. 5.1 Groundwater Quality Protection The District conducts an extensive program aimed at protecting the quality of the water in the basin. These programs include groundwater monitoring, participating in and supporting voluntary watershed water quality studies and regulatory programs, working with groundwater producers, providing technical assistance, and conducting public education programs. 5.1.1 OCWD GROUNDWATER QUALITY PROTECTION POLICY OCWD adopted the Groundwater Quality Protection Policy in May 1987, in recognition of the serious threat posed by groundwater contamination; passage was based on the statutory authority granted under Section 2 of the District Act. The objectives of the policy are to: • Maintain groundwater quality suitable for all existing and potential beneficial uses; • Prevent degradation of groundwater quality; • Assist regulatory agencies in identifying the sources of contamination to assure cleanup by the responsible parties; • Maintain or increase the basin’s usable storage capacity; and • Inform the general public, regulatory agencies and Producers of the condition of the groundwater basin and of water quality problems as they are discovered. Eight specific programs established to achieve these objectives are: • Water quality monitoring of surface and groundwater; • Identification, interim containment, and cleanup of contamination; • Coordinated operation with regulatory agencies; • Control of toxic residuals; GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-1 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT • Hazardous waste management planning; • Dissemination of technical information; • Public disclosure; and • Groundwater protection evaluation. A key component of the policy describes circumstances under which the District will undertake contamination cleanup activities at District expense. This becomes necessary when contamination poses a significant threat and the party responsible for the contamination cannot be identified, is unable to cleanup the contamination, or is unwilling to cleanup the contamination. When appropriate to protect water quality in the basin, OCWD provides financial incentives for Producers to pump and treat groundwater that does not meet drinking water quality standards. These so-called “Basin Equity Assessment (BEA) Exemptions” are explained in Section 5.9. 5.1.2 WATER QUALITY TREATMENT GOALS FOR GROUNDWATER PROGRAMS OCWD encourages clean up of groundwater to maximize beneficial use of contaminated water in areas with high concentrations of TDS, nitrates, selenium, color, organic compounds, and other constituents exceeding drinking water standards. Treatment goals include: • State primary and secondary drinking water standards must be met when water is used for potable supplies. • Treatment for irrigation water shall meet criteria necessary for the intended beneficial use. • The District shall pursue payment or reimbursement of cleanup costs from the responsible party when contamination originates from a known source. 5.1.3 REGULATION AND MANAGEMENT OF CONTAMINANTS A variety of federal, state, county and local agencies have jurisdiction over the regulation and management of hazardous substances and the remediation of contamination of groundwater and drinking water supplies. For example, the County of Orange Health Care Agency (OCHCA) regulates leaking underground fuel tanks except in cases where the city is the lead agency. OCWD does not have regulatory authority to require responsible parties or potential responsible parties to clean up pollutants that have contaminated groundwater. In some cases, the District has pursued legal action against entities that have contaminated the groundwater basin to recover the District’s remediation costs. In other cases, the District coordinates and cooperates with regulatory oversight agencies that investigate sources of contamination and assess the potential threat that the contamination poses to public health and the environment in the Santa Ana River watershed and within the County of Orange. Some of these efforts include: • Reviewing on-going groundwater cleanup site investigations and commenting on the findings, conclusions, and technical merits of progress reports. • Providing knowledge and expertise to assess contaminated sites and evaluating the merits of proposed remedial activities. 5-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT • Conducting third party groundwater split samples at contaminated sites to assist regulatory agencies in evaluating progress of groundwater cleanup and/or providing confirmation data of the areal extent of contamination. 5.1.4 LAND USE AND DEVELOPMENT Protecting groundwater from contamination protects public health and prevents loss of valuable groundwater resources. Managing land use and planning for future development are key management activities essential for protecting water quality and reducing the risk of contamination. OCWD monitors, reviews, and comments on environmental documents such as Environmental Impact Reports (EIR), Notices of Preparation, proposed zoning changes, and land development projects. District staff also review draft National Pollution Discharge Elimination System (NPDES) and waste discharge permits issued by the Santa Ana Regional Water Quality Control Board The proposed projects and programs may have elements that could cause short or long term water quality impacts to source water used for groundwater replenishment or have the potential to degrade groundwater resources. Monitoring and reviewing waste discharge permits provides the District with insight on activities in the watershed that could affect water quality. The majority of the basin’s land area is located in a highly urbanized setting and requires tailored water supply protection strategies. Reviewing and commenting on stormwater permits adopted by the for the portions of Orange, Riverside, and San Bernardino Counties that are within the Santa Ana River watershed are important. These permits can affect the quality of water in the Santa Ana River and other water bodies, thereby impacting groundwater quality in the basin. OCWD works with local agencies having oversight responsibilities on the handling, use, and storage of hazardous materials; underground tank permitting; well abandonment programs; septic tank upgrades; and drainage issues. Participating in basin planning activities of the and serving on technical advisory committees and task forces related to water quality are also valuable activities to protect water quality. 5.1.5 DRINKING WATER SOURCE ASSESSMENT AND PROTECTION PROGRAM To comply with federal Safe Drinking Water Act requirements regarding the protection of drinking water sources, the California Department of Public Health (CDPH) created the Drinking Water Source Assessment and Protection (DWSAP) program. Water suppliers must submit a DWSAP report as part of the drinking water well permitting process and have it approved before providing a new source of water from a new well. OCWD provides technical support to Producers in the preparation of these reports. This program requires all well owners to prepare a drinking water source assessment and establish a source water protection program for all new wells. The source water program must include: a delineation of the land area to be protected, the identification of all potential sources of contamination to the well, and a description of management strategies aimed at preventing groundwater contamination. Managing land use and planning for future development are key management activities essential GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-3 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT for protecting, preventing, and reducing contaminant risks to future drinking water supplies. Developing management strategies to prevent, reduce, or eliminate risks of groundwater contamination is one component of the multiple barrier protection of source water. Contingency planning is an essential component of a complete DWSAP and includes developing alternate water supplies for unexpected loss of each drinking water source, by man-made or catastrophic events. 5.1.6 WELL CONSTRUCTION POLICIES Wells constructed by the District are built to prevent the migration of surface contamination into the subsurface. This is achieved through the placement of annular well seals and surface seals during construction. Also, seals are placed within the borehole annulus between aquifers to minimize the potential for flow between aquifers. Well construction ordinances adopted and implemented by the OCHCA and municipalities follow state well construction standards established to protect water quality under California Water Code Section 231. To provide guidance and policy recommendations on these ordinances, the County of Orange established the Well Standards Advisory Board in the early 1970s. The five-member appointed Board includes the District’s Hydrogeologist. Recommendations of the Board are used by the OCHCA and municipalities to enforce well construction ordinances within their jurisdictions. 5.1.7 WELL CLOSURE PROGRAM FOR ABANDONED WELLS A well is considered abandoned when either the owner has permanently discontinued its use or it is in such a condition that it can no longer be used for its intended purpose. This often occurs when wells have been forgotten by the owner, were not disclosed to a new property owner, or when the owner is unknown. Past research conducted by OCWD identified approximately 1,400 abandoned wells which were not properly closed. Many of these wells may not be able to be properly closed due to overlying structures, landscaping, or pavement. Some of them may pose a threat to water quality because they can be conduits for contaminant movement as well as physical hazards to humans and/or animals. OCWD supports and encourages efforts to properly close abandoned wells. As part of routine monitoring of the groundwater basin, OCWD will investigate on a case-by-case basis any location where data suggests that an abandoned well may be present and may be threatening water quality. When an abandoned well is found to be a significant threat to the quality of groundwater, OCWD will work with the well owner to properly close the well. The City of Anaheim has a well destruction policy and has an annual budget to destroy one or two wells per year. The funds are used when an abandoned well is determined to be a public nuisance or needs to be destroyed to allow development of the site. The city’s well permit program requires all well owners to destroy their wells when they are no longer needed. When grant funding becomes available, the city uses the funds to 5-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT destroy wells where a responsible party has not been determined and where the well was previously owned by a defunct water consortium. 5.2 Salinity Management Increasing salinity is a significant water quality problem in many parts of the southwestern United States and Southern California, including Orange County. Elevated salinity levels can contaminate groundwater supplies, constrain implementation of water recycling projects and cause other negative economic impacts such as the need for increased water treatment by residential, industrial, commercial users, and water utilities. Often a component of salinity, elevated levels of nitrates pose a risk to human health. 5.2.1 SOURCES OF SALINITY Salinity is a measure of the dissolved minerals in water. Also referred to as salts or TDS, salinity is measured in the laboratory by evaporating a known volume of water to dryness and measuring the remaining salts. Dissolved minerals are composed of positively charged cations and negatively charged anions. Principal cations include sodium, calcium, potassium, and magnesium. Key anions are chloride, sulfate, carbonate, and bicarbonate. Water’s hardness, related to TDS, refers to the measure of divalent metallic cations, principally calcium and magnesium. High salinity and hardness limit the beneficial uses of water for domestic, industrial, and agricultural applications. Hard water causes scale formation in boilers, pipes, and heat- exchange equipment as well as soap scum and an increase in detergent use. This can result in the need to replace plumbing and appliances and require increased water treatment. Some industrial processes, such as computer microchip manufacturers, must have low TDS in the process water and often must treat the municipal supply prior to use. High salinity water may reduce plant growth and crop yield, and clog drip irrigation lines. In coastal areas, seawater intrusion can be a major source of increased salinity in groundwater. Other identified sources of coastal groundwater salinity include connate water (water trapped in the pores of the sediment at the time the sediments were deposited) and brines disposed from past oil production. 5.2.2 REGULATION OF SALINITY TDS is regulated by the EPA and the CDPH as a constituent that affects the aesthetic quality of water – notably, taste. The recommended secondary MCLs for key constituents comprising TDS are listed in Table 5-1. At the state level, TDS levels in groundwater are managed by the which delegates this authority to the regional boards. The Santa Ana salinity management program was developed with extensive stakeholder input. The Santa Ana Watershed is divided into management zones and allowable TDS levels are determined GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-5 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT for each of those zones. The Orange County groundwater basin is divided into two management zones as shown in Figure 5-1. TABLE 5-1 SECONDARY DRINKING WATER STANDARDS FOR SELECTED CONSTITUENTS Constituent Recommended Secondary MCL, mg/L Total Dissolved Solids (salts) 500 Chloride 250 Sulfate 250 FIGURE 5-1 Groundwater Management Zones 5-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-7 To set the allowable levels of TDS for each management zone, historical ambient or baseline conditions were determined. These were used by the to set ‘Water Quality Objectives” for each management zone, which were officially adopted as part of the Water Quality Control Plan for the Santa Ana River Basin, also referred to as “the Basin Plan.” The levels of TDS in each groundwater management zone are measured periodically and compared to the adopted objectives. When a newly determined ambient level is equal to or greater than the established objective, that management zone does not have an “assimilative capacity.” This means that the quality of the groundwater in that zone is determined to be incapable of successfully assimilating increased loads of TDS without degrading the water quality. Conversely, when an updated ambient level is lower than the established objective, that management zone has an assimilative capacity and is determined to be capable of receiving modest inputs of TDS without exceeding the Water Quality Objective. The Water Quality Objectives and ambient quality levels for the two Orange County management zones are shown in Table 5-2. Comparing the ambient water quality to the TDS objectives indicates that neither one of these zones have assimilative capacity for TDS. TABLE 5-2 TDS WATER QUALITY OBJECTIVES FOR LOWER SANTA ANA RIVER BASIN MANAGEMENT ZONES Management Zone Water Quality Objective (mg/L) Ambient Quality (mg/L) Orange County 580 590 Irvine 910 920 (Wildermuth, 2008) 5.2.3 SALINITY IN THE GROUNDWATER BASIN As explained in Section 3, OCWD monitors the levels of TDS in wells throughout the groundwater basin. Figure 5-2 shows the average TDS at production wells in the basin for the period of 2004 to 2008. In general, the portions of the basin with the highest TDS levels are located in areas of Irvine, Tustin, Yorba Linda, Anaheim and Fullerton. In addition, there is a broad area in the middle portion of the basin where the TDS generally ranges from 500 to 700 mg/L. Localized areas near the coast, where water production does not occur, contain relatively higher TDS concentrations. Managing salinity levels in the basin and in recharge water is an important objective for the District. As explained in Section 4, water that recharges the Orange County groundwater basin includes: • Santa Ana River baseflow and stormflow, • Groundwater Replenishment System water, and • Incidental recharge, including precipitation and irrigation return flows. ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT FIGURE 5-2 TDS IN GROUNDWATER PRODUCTION WELLS Understanding the sources of salt and measuring the concentrations of TDS in each of the recharge sources is an important aspect in managing salinity. Table 5-3 presents the estimated salt inflows for the basin using average recharge volumes. The inflows used here are the same as those used in calculating the basin water budget as explained in Section 2.3 and displayed in Table 2-2. TDS concentrations for the inflows were based on flow and water quality data collected by the District and the USGS. The Talbert injection barrier was calculated with the assumption that barrier water is from the GWR System and the Alamitos injection barrier was calculated using 5-8 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-9 the assumption that injection water is a 50:50 blend of recycled water and imported water. The flow-weighted TDS of local incidental recharge of 1,100 mg/L was calculated using estimates of the TDS concentration of each component listed in Table 2-2. For subsurface inflow and recharge from the foothills, the TDS concentration was estimated using data from the closest nearby wells. As shown in Table 5-3, the District estimates that the flow-weighted average inflow TDS concentration is 536 mg/L. It is important to note that the TDS concentration of GWR System water is 60 mg/L. OCWD anticipates that over time the use of GWR System water for Talbert Barrier operations and groundwater recharge will have a positive impact on the salt balance of the groundwater basin. TABLE 5-3 SALT INFLOWS FOR ORANGE COUNTY AND IRVINE MANAGEMENT ZONES Inflow (afy) TDS (mg/L) Salt (tons/yr) Recharged SAR Baseflow 148,000 620 125,000 Recharged SAR Stormflow 50,000 200 14,000 GWR System water recharge in Anaheim 37,000 60 3,000 Unmeasured Recharge (Incidental) 69,000 1,100 104,000 Injection Barriers Talbert 35,000 60 2,900 Alamitos 2,500 350 1,200 Total: 341,500 536* 250,100 * Flow weighted Figure 5-3 illustrates TDS concentrations through time at a well in Santa Ana. The location of well SA-16 is shown on Figure 5-2. The TDS concentration at well SA-16 increased from approximately 200 to 300 mg/L in the mid-1960s to approximately 600 mg/L by the mid-1980s. From the mid-1980s to 2008, the TDS concentration varied between 500 to 700 mg/L. ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT FIGURE 5-3 TDS IN A POTABLE SUPPLY WELL (SA-16/1) 100 200 300 400 500 600 [PHONE REDACTED] 1965 1971 1976 1982 1987 1993 1998 2004 2009 Total Dissolved Solids (TDS) mg/L Recommended Secondary Drinking Water Standard TDS = 500 mg/L Well location: Santa Ana Pressure Area Well screen perforated interval: 305 to 950 feet bgs Sample Date 5.2.4 ECONOMIC IMPACTS OF INCREASING SALINITY Increasing salinity of water supplies directly impacts consumer costs. A technical investigation of salinity impacts on water supplies of Southern California was published in 1999 by the United States Department of Interior, U.S. Bureau of Reclamation and the Metropolitan Water District of Southern California. The Salinity Management Study assessed economic impacts of salinity increases in Colorado River water and State Water Project water. The model was developed to account for regional differences in water deliveries, demographics, TDS concentrations, and average water use per household or by agriculture or industry. The study estimated a regional economic benefit of $95 million per year (calculated in 1998 dollars) for a 100 mg/L decrease in imported water supply TDS in the Metropolitan region. Conversely, a 100 mg/L increase in TDS would increase consumer costs by $95 million annually as shown in Figure 5-4. Approximately $18 million annually would be realized in cost savings for groundwater supplies. Residential cost savings were estimated at $35 million per year. Figure 5-5 shows $64 million of benefits if most local groundwater (about 90 percent) and wastewater (about 80 percent) were to experience a 100 mg/L decrease in salinity. 5-10 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT FIGURE 5-4 ANNUAL ECONOMIC BENEFITS OF 100 MG/L SALINITY DECREASE IMPORTED WATER SUPPLIES Source: MWD and Bureau of Reclamation Salinity Management Study (1999) Residential $35 Million Commercial $10 Million Industrial $5 Million Agricultural $14 Million Utilities $8 Million Groundwater $18 Million Recycled Water $5 Million FIGURE 5-5 ANNUAL ECONOMIC BENEFITS OF 100 MG/L SALINITY DECREASE GROUNDWATER AND WASTEWATER Commercial $7 Million Industrial $3 Million Agricultural $4 Million Utilities $6 Million Groundwater $14 Million Residential $21 Million Recycled Water $9 Million Source: MWD and Bureau of Reclamation Salinity Management Study (1999) Table 5-4 summarizes the economic benefits to water users from salinity reduction. Cost savings include reduced need to construct desalting facilities and greater compliance of wastewater discharges with permit requirements. Residential consumer cost savings would be realized in longer lifespan for appliances and plumbing as well as the reduced need for water softening devices. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-11 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT TABLE 5-4 SUMMARY OF ECONOMIC BENEFITS OF REDUCED SALINITY User Economic Benefit Increased life of plumbing system and appliances Residential Reduced use of bottled water and water softeners Decreased cost of water softening Decreased use of water for cooling Commercial Increased equipment service life Decreased cost of water treatment Decreased water usage Industrial Decreased sewer fees Increased crop yield Agricultural Decreased water usage for leaching purposes Utilities Increased life of treatment facilities and pipelines Improved wastewater discharge requirements for permit compliance Groundwater Decreased desalination and brine disposal costs Decreased use of imported water for salt management Recycled Water Decreased desalination and brine disposal costs MWD/USBR 1999 Salinity Management Study 5.2.5 SALINITY MANAGEMENT PROJECTS IN THE UPPER WATERSHED The District has a long-standing commitment to management of salinity in groundwater supplies, avoiding the loss of water supplies due to increased salinity, and developing projects to reduce salinity are District priorities. Since the Santa Ana River is the primary source of recharge water for the basin, salt management programs in the upper watershed are vital to protect the water quality in Orange County; success in this regard requires participation and cooperation of upper Santa Ana watershed stakeholders. Several desalters, which are water treatment plants designed to remove salts, have been built in Riverside and San Bernardino Counties. These plants are effectively reducing the amount of salt buildup in the watershed. The Santa Ana Regional Interceptor (SARI), built by the Santa Ana Watershed Project Authority (SAWPA), began operation in 1975 to remove salt from the watershed by transporting industrial wastewater and brine produced by desalter operations directly to the OCSD for treatment. Approximately 75,000 tons of salt were removed by the SARI line in FY 2006-07. 5-12 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-13 The other “brine line” in the upper watershed, the Non-reclaimable Waste Line in the Chino Basin operated by the Inland Empire Utilities Agency (IEUA), segregates high TDS industrial wastewater. 5.2.6 OCWD SALINITY MANAGEMENT AND REMEDIATION PROGRAMS Within Orange County, operations of the GWR System and several local and regional groundwater desalters are working to reduce salt levels. The GWR System, described in Section 4.2, purifies wastewater that is used for groundwater recharge and for injection into the Talbert Barrier to prevent seawater intrusion. The GWR System provides a dependable supply of low salinity water, whose quantity and quality will not be impacted by future drought conditions. The GWR System is expected to reduce the basin salt load by approximately 48,000 tons/year, based on the difference between recharging 72,000 afy of GWR System water at 60 mg/L and an equal amount of imported blended Colorado River and SPW water at 550 mg/L. High salinity groundwater areas located in Tustin and Irvine are being treated through the operation of desalter plants; these projects are described in Section 5.8. 5.2.7 SEAWATER INTRUSION BARRIERS OCWD’s Talbert Barrier is composed of a series of injection wells that span the 2.5-mile-wide Talbert Gap between the Newport and Huntington mesas (see Figure 3-9). From 1975 until 2004, a blend of purified water from OCWD’s WF-21, deep aquifer water, and imported potable water was injected into the barrier. The Talbert Barrier wells were used to inject an average of 12 mgd of water into four aquifer zones to form a hydraulic barrier to seawater that would otherwise migrate inland toward areas of groundwater production. The GWR System began operations in January 2008 to better control seawater intrusion as well as to recharge the coastal aquifers. Twelve new wells enable injection of up to 35 mgd of purified water into the expanded injection barrier. Figure 5-6 shows the total flow-weighted average of TDS levels of the Talbert Barrier Injection Water. Prior to 2004, injection water was a blend of imported water, WF-21 purified water, and deep aquifer water. During the time that WF-21 was decommissioned and the GWR System was in construction, a blend of imported water, potable water, and deep aquifer water was injected into the barrier. In 2007, only treated, imported water was used resulting in a flow weighted average TDS of Talbert Barrier injection water of 477 mg/L. With 84 percent of injection water supplied by the GWR System, the flow weighted average for 2008 dropped to 117 mg/L. ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT FIGURE 5-6 TALBERT BARRIER INJECTION WATER - TOTAL DISSOLVED SOLIDS (TDS) Total Flow Weighted Average TDS of All Source Waters 0 100 200 300 400 [PHONE REDACTED] 1980 1985 1990 1995 2000 2005 2010 Recommended Secondary Drinking Water Standard for TDS = 500 mg/L 2007 = Treated, imported water used for injection; no recycled water injected 2008 = Blend of GWRS product water (84%) and imported water(16%) Flow weighted average TDS (mg/L) The Alamitos seawater intrusion barrier is composed of a series of injection wells that span the Los Angeles/Orange County line in the Seal Beach-Long Beach area. It is operated by the LACDPW in cooperation with OCWD and the WRD. The source of this water is a blend of purified water from WRD and potable supplies from Metropolitan. 5.3 Nitrate Management Nitrate is one of the most common and widespread contaminants in groundwater supplies. OCWD conducts an extensive program to protect the basin from nitrate contamination. The District regularly monitors nitrate levels in groundwater, operates 465 acres of wetlands in the Prado Basin to remove nitrates in Santa Ana River water, and works with Producers to treat individual wells when nitrate levels exceed safe levels. 5.3.1 SOURCES OF NITRATES Nitrogen is an element essential for plant growth; in the environment it naturally converts to nitrate. Nitrate is a nitrogen-oxygen ion (NO3⎯) that is very soluble and mobile in water. Elevated levels of nitrate in soil and water supplies originate from fertilizer use, animal feedlots, wastewater disposal systems, and other sources. Plants and bacteria break down nitrate but excess amounts can leach into groundwater; once in the groundwater, nitrate can remain relatively stable for years. 5-14 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT The primary concern for human health is not nitrate but its conversion to nitrite (NO2¯) in the body. Nitrite oxidizes iron in the hemoglobin of red blood cells to form methemoglobin, depriving the blood of oxygen. This is hazardous to infants as they do not yet have enzymes in their blood to counteract this process. They can suffer oxygen deficiency called methemoglobinemia, commonly known as “blue baby named for its most noticeable of bluish skin coloring. 5.3.2 REGULATION OF NITRATE Both federal and state agencies regulate nitrate levels in water. The EPA and CDPH set the MCL in drinking water at 10 mg/L for nitrate-nitrogen. The Santa Ana Watershed is divided into management zones with nitrate-nitrogen water quality objectives set for each of those zones. These levels are determined after considering historical ambient or baseline conditions. Water quality objectives and ambient quality levels for Orange County’s management zones are shown in Table 5-5. The main Orange County basin has a minor amount of assimilative capacity but the Irvine subbasin has none. Efforts to reduce nitrate levels in the Irvine subbasin are described in Section 5.8. TABLE 5-5 NITRATE-NITROGEN WATER QUALITY OBJECTIVE FOR LOWER SANTA ANA RIVER BASIN MANAGEMENT ZONES Management Zone Water Quality Objective Ambient Quality Orange County 3.4 mg/L 3.0 mg/L Irvine 5.9 mg/L 6.5 mg/L Source: Recomputation of Ambient Water Quality for the Period 1987 to 2006 prepared by Wildermuth Environmental, August 2008. 5.3.3 OCWD NITRATE MANAGEMENT AND REMEDIATION PROGRAMS One of the District’s programs to reduce nitrate levels in the groundwater basin is managing the nitrate concentration of water recharged by the District’s facilities. This includes managing the quality of surface water flowing to Orange County through Prado Dam. As explained in Section 4, the primary source of recharge water for the groundwater basin is the Santa Ana River. To reduce the level of nitrate entering Orange County from the Santa Ana River, OCWD operates an extensive system of wetlands in the Prado Basin as shown in Figure 4-3. OCWD diverts river flows through a 465-acre system of constructed wetlands, shown in Figure 5-7, where nitrates are naturally removed from the water. The wetlands provide a natural treatment system that removes approximately 15 to 40 tons of nitrates a month depending on the season. The wetlands are more effective from May through October when the water temperatures are warmer. During summer months the wetlands reduce nitrate from nearly 10 mg/L to 1 to 2 mg/L. In 2004-05, the wetlands were damaged by flooding. The wetlands were reconstructed and placed back in service in 2008. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-15 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT All production wells are tested annually for nitrate; wells with concentrations equal to or greater than 50 percent of the MCL are monitored on a quarterly basis. Areas where nitrate concentrations exceed the MCL are shown in Figure 5-8. FIGURE 5-7 PRADO WETLANDS FIGURE 5-8 AREAS WITH ELEVATED NITRATE LEVELS 5-16 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT Within Orange County, nitrate-nitrogen levels in groundwater generally range from 4 to 7 mg/L in the Forebay area and from 1 to 4 mg/L in the Pressure area. Ninety-eight percent of the drinking water wells meet drinking water standards for nitrate-nitrogen as shown in Figure 5-9. The two percent above MCL are treated to reduce nitrate levels prior to being served to customers. Areas in the basin where nitrate levels exceed the MCL are suspected to be impacted by historical fertilizer use. OCWD works with the Producers to address areas of high nitrate levels. The Tustin Main Street Treatment Plant, described in Section 5.8, is an example of such an effort. FIGURE 5-9 PERCENT OF WELLS MEETING THE DRINKING WATER STANDARD (MCL) 2007 AVERAGE NITRATE DATA Meet MCL Exceed MCL 98% Wells meet the drinking water standard for nitrate Wells are treated to reduce nitrate to levels meeting the standard before served to customers Nitrate-Nitrogen (NO3-N) MCL = 10 mg/L 2% Wells do not meet the drinking water standard for nitrates 5.4 Colored Groundwater Management This section discusses the occurrence of colored groundwater, the challenges of developing colored water sources, and production processes used to treat colored water. 5.4.1 OCCURRENCE OF COLORED WATER IN THE BASIN Colored water is found in deep aquifers (600-2000 feet) over a broad region in the Lower Main aquifer, as shown in Figures 5-10 and 5-11. Natural organic material from ancient redwood forests and peat bogs gives the water an amber tint and a sulfur odor. Although colored water is of very high quality, negative aesthetic qualities, its color and odor, require treatment before use as drinking water. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-17 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT FIGURE 5-10 CROSS-SECTION OF AQUIFERS SHOWING COLORED WATER AREAS Costa Mesa Costa Mesa Orange Orange NON-WATERBEARING FORMATION 0 0 700 700’ 1,400 1,400’ 2,100 2,100’ 5 10 10 15 15 20 20 0’ Colored Water PRINCIPAL AQUIFER DEEP AQUIFER SHALLOW AQUIFER Santa Ana Santa Ana Miles from Ocean Costa Mesa Costa Mesa Orange Orange NON-WATERBEARING FORMATION 0 0 700 700’ 1,400 1,400’ 2,100 2,100’ 5 10 10 15 15 20 20 0’ Colored Water PRINCIPAL AQUIFER DEEP AQUIFER SHALLOW AQUIFER Santa Ana Santa Ana Miles from Ocean The total amount of colored groundwater is estimated to be over one million acre feet, perhaps as much as several million acre feet. Economic constraints pose challenges to developing colored water supplies as the water needs to be treated to remove the color and odor. Costs depend on the water quality (color and other parameters) and the type and extent of required treatment. An additional factor that must be considered is the impact of water levels in the clear zone compared to water levels in the deeper aquifers with colored water. Monitoring wells reveal a correlation of clear/colored zone water level fluctuations, indicating a fairly strong hydrologic connection between the two zones in some areas of the basin. Three facilities currently treat colored groundwater in Orange County. Mesa Consolidated Water District (MCWD) has operated an ozone oxidation treatment facility since 1985 at its Well No. 4 site. In 2001, MCWD opened its Colored Water Treatment Facility (CWTF) using ozone treatment to produce 4,000 gallons per minute. The third facility is the Deep Aquifer Treatment System (DATS), a treatment facility using nano-filtration membranes operated by IRWD since 2002. This facility purifies 7.4 mgd of colored water. 5-18 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT FIGURE 5-11 EXTENT OF COLORED WATER 5.5 Organic Contaminants Ninety-five percent of the basin’s groundwater used for drinking water supplies is pumped from the main aquifer. Water from this aquifer continues to be of high quality. This section describes areas of the basin that are experiencing contamination threats, most of which occur in the shallow aquifer. 5.5.1 METHYL TERTIARY BUTYL ETHER (MTBE) During the 1980s, gasoline hydrocarbons of greatest risk to drinking water were benzene, toluene, and xylenes, collectively known as BTEX chemicals. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-19 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT Although leaking underground fuel tanks were identified throughout the basin, these chemicals typically were degraded by naturally-occurring microbes that allowed clean up by natural attenuation or passive bioremediation. Unfortunately, a new additive to gasoline aimed at reducing air pollution has become a widespread contaminant in groundwater supplies. Methyl tertiary butyl ether (MTBE) is a organic chemical that was added to gasoline to increase octane ratings during the phase-out of leaded gasoline. In the mid-1990s, the percentage of MTBE added to gasoline increased significantly to reduce air emissions. MTBE is a serious threat to groundwater quality; it sorbs weakly to soil and does not readily biodegrade. The greatest source of contamination comes from releases from underground fuel tanks. The State of California banned the use of the additive in 2004 in response to its widespread detection in groundwater throughout the state. The CDPH set the primary MCL for MTBE in drinking water at 13 µg/L. The secondary MCL for MTBE is 5 µg/L. Drinking water wells in the basin are tested annually for VOC analytes including MTBE. The District continues to work with local water agencies to monitor for MTBE and other fuel-related contaminants to identify areas that may have potential underground storage tank problems and releases resulting in groundwater contamination. 5.5.2 VOLATILE ORGANIC COMPOUNDS VOCs in groundwater come from a number of sources. From the late 1950s through early 1980s, VOCs were used for industrial degreasing in metals and electronics manufacturing. Other common sources include paint thinners and dry cleaning solvents. VOC contamination is found in several locations in the basin. In 1985, a contamination site was discovered beneath the former El Toro MCAS. Monitoring wells at the El Toro site installed by the U.S. Navy and OCWD delineated a one-mile wide by three-mile long VOC plume, comprised primarily of trichloroethylene (TCE). Beneath the former Air Station, VOC contamination was primarily found in the shallow groundwater up to 150 feet below the ground surface. Off-base, to the west, the VOC plume is in deeper aquifers from 200 to 600 feet deep. Another VOC contamination site was found in portions of the shallow aquifer in the northern portion of the Orange County in the cities of Fullerton and Anaheim. Although not directly used for drinking water supplies, groundwater in the shallow aquifer eventually flows into the deeper principal aquifer, which is used for potable water supplies. To date, two city of Fullerton production wells have been removed from service and destroyed due to VOC contamination in that area. Currently, there are no production wells in that area that extract water from the shallow aquifer. The North Basin Groundwater Protection Project, described in Section 5.8, was initiated in 2005 to clean up the groundwater in this portion of the basin. Elevated concentrations of perchloroethylene (PCE), TCE, and perchlorate were detected in IRWD’s well No. 3, located in Santa Ana. OCWD is currently working with the Regional Board and the California Department of Toxic Substances Control to require aggressive cleanup actions at nearby sites that are potential sources of the 5-20 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT contamination. OCWD has initiated the South Basin Groundwater Protection Project described in Section 5.8 to address this contamination. 5.5.3 N-NITROSODIMETHYLAMINE (NDMA) NDMA is a low molecular weight compound that can form in influent water entering wastewater treatment plants and after chlorine disinfection of wastewater. It is also found in food products such as cured meat, fish, beer, milk, and tobacco smoke. OCWD is monitoring NDMA levels in the groundwater basin. The California Notification Level for NDMA is 10 nanograms per liter (ng/L). The concentration of NDMA is typically less than 2 ng/L in the Santa Ana River at Imperial Highway. At OCWD’s GWR System in Fountain Valley, NDMA concentrations are maintained below California’s Notification Level through a combination of source control measures, reverse osmosis treatment, and advanced oxidation treatment using ultraviolet light and hydrogen peroxide. 5.5.4 1,4-DIOXANE A suspected human carcinogen, 1,4-dioxane, is used as a solvent in various industrial processes such as the manufacture of adhesive products and membranes and may occur in consumer products such as detergents, cosmetics, pharmaceuticals, and food products. In 2002, OCWD detected elevated levels of 1,4-dioxane in nine production wells exceeding the California Action Level. These wells were temporarily shutdown with a loss of 34 mgd of water supply. Further investigation traced the contaminant to one industrial discharger that was discharging 1,4-dioxane into wastewater collected by OCSD. This discharge was affecting water that was treated by WF-21 and injected into the Talbert Seawater Barrier. The discharger voluntarily ceased discharge of 1,4-dioxane and concentrations declined. Additional monitoring data showed low concentrations, the CDPH determined that the water was not a significant risk to health, and the wells were returned to service. 5.6 Perchlorate Perchlorate has been detected at wells distributed over a large area of the groundwater basin. Based on data from 217 active production wells over the last three years and a detection limit of 2.5 micrograms per liter, perchlorate was not detected at 83 percent of the wells. Seventeen percent of the wells had detectable concentrations of perchlorate. For those wells with detectable amounts of perchlorate, 89 percent of the wells have detected perchlorate concentrations below the California primary drinking water standard of 6 micrograms per liter. Four of the 217 active production wells had perchlorate concentrations greater than 6 micrograms per liter. It is important to note that water delivered for municipal purposes meets the primary drinking water standard. Groundwater from production wells that have perchlorate concentrations over the primary drinking water standard is treated to reduce the perchlorate concentration below the primary drinking water standard prior to delivery for municipal usage. Sources of perchlorate in the groundwater basin may include: • Fertilizer application; GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-21 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT • Water imported from the Colorado River (through the use of Colorado River water for groundwater recharge, irrigation, or water supplies that impact the groundwater basin through onsite wastewater disposal systems); • Industrial or military sites that used, disposed of, or stored perchlorate. Perchlorate has historically been used as an ingredient in rocket propellant, explosives, fireworks, and road flares; and • Naturally occurring perchlorate perchlorate in rainfall). The occurrence of perchlorate in Chilean fertilizer applied for agricultural purposes has been documented in various studies (see for example, the discussion in the December 1, 2006 publication of the journal Analytical Chemistry (Foubister, 2006); see also Urbansky et al (2001)). The occurrence of perchlorate in historic supplies of Colorado River water has been documented in published studies (see for example, the report published by the National Research Council in 2005 titled “Health Implications of Perchlorate Ingestion” (National Research Council, 2006); see also Urbansky et al (2001)). Due to source remediation efforts near Henderson, Nevada, the concentration of perchlorate in Colorado River water has decreased (Nevada Division of Environmental Protection, 2009). Perchlorate has been detected in groundwater at various sites in California in association with industrial or military sites (Interstate Technology & Regulatory Council, 2005). Perchlorate has been detected in rainfall (see for example, the report published by the Interstate Technology & Regulatory Council, 2005 and Dasgupta et al (2005)). The District’s ongoing monitoring program is continuing to assess the distribution of perchlorate in the groundwater basin and how concentrations change through time. The District regularly reviews this information and will continue to work with the stakeholders to address this issue. 5.7 Constituents of Emerging Concern Constituents of emerging concern are or naturally occurring substances (chemicals and microorganisms) that are not regulated but may have negative impacts on the environment and/or human health. The newest group of constituents of emerging concern includes pharmaceuticals, personal care products, and endocrine disruptors. Pharmaceuticals and personal care products include thousands of chemicals contained in consumer and health related products such as drugs (prescription and over-the-counter), food supplements, fragrances, sun-screen agents, deodorants, flavoring agents, insect repellants, and inert ingredients. Important classes of high use prescription drugs include antibiotics, hormones, beta-blockers (blood pressure medicine), analgesics (pain-killers), steroids, antiepileptic, sedatives, and lipid regulators. Endocrine Disrupting Compounds (EDCs) are compounds that can disrupt the endocrine system. They can occur in a wide variety of products such as pesticides and pharmaceuticals. Research investigations have documented that EDCs can interfere with the normal function of hormones that affect growth and reproduction in animals and 5-22 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT humans. Findings of secondary sex changes, poor hatching, decreased fertility, and altered behavior have been observed in fish following exposure to EDCs. In general, these substances have been identified as a pollution threat or were previously detected in the environment. As new laboratory methods are developed, substances can be detected at much lower concentrations. When such detection occurs before regulatory limits are established and potential human health effects are still unknown, water suppliers and health officials face new challenges. In some cases, public awareness and concern is high because the compounds are detected but scientific-based information on potential health impacts of such low concentrations is not available. Water quality concerns arise from the widespread use of and EDCs. In most cases, the impacts on human health from exposure to low concentrations of these substances are not known. European studies in the 1990s confirmed the presence of some of these chemicals in the less than one microgram per liter range (ppb) in surface waters and groundwater and at low concentrations in wastewater treatment plant effluents. A USGS report found detectable concentrations of hormones and in many vulnerable waterways throughout the United States (Kolpin 2002). Due to the potential impact of EDCs on future water reclamation projects, the District prioritizes monitoring of these chemicals. OCWD’s state-certified laboratory is one of a few in the state that has a program to continuously develop capabilities to analyze for new compounds. Recognizing that the state CDPH has limited resources to focus on methods development, OCWD works on developing low detection levels for chemicals likely to be targeted for future regulation or monitoring. OCWD advocates the following general principles as water suppliers and regulators develop programs to protect public health and the environmental from adverse effects of these emerging contaminants: • Monitoring should focus on constituents that pose the greatest risk. • Constituents that are prevalent, persistent in the environment, and may occur in unsafe concentrations should be prioritized. • Analytical methods to detect these constituents should be approved by the state or federal government. • Studies to evaluate the potential risk to human health and the environment should be funded by the state or federal government. • The state and federal government should encourage programs to educate the public on waste minimization and proper disposal of unused pharmaceuticals. OCWD is committed to track new compounds of concern; research chemical occurrence and treatment; communicate closely with CDPH on prioritizing investigation and guidance; coordinate with OCSD, upper watershed wastewater dischargers, and regulatory agencies to identify sources and reduce contaminant releases; and inform the Producers on emerging issues. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-23 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT 5.8 Groundwater Quality Improvement Projects This section describes specific projects that improve groundwater quality by removing TDS, nitrate, VOCs and other constituents as shown in Figure 5-12. Two water quality improvement projects discussed in the 2004 Groundwater Management Plan are no longer in operation. The Fullerton Iron and Manganese Removal Project was determined to be ineffective due to well capacity limitations. The Orange TCE project operated only on a temporary basis and has been permanently shut down. FIGURE 5-12 WATER QUALITY IMPROVEMENT PROJECTS 5-24 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT 5.8.1 NORTH BASIN GROUNDWATER PROTECTION PROJECT In accordance with OCWD’s groundwater cleanup policy, the District is implementing the to protect drinking water supplies and the beneficial use of groundwater. OCWD has constructed five wells specifically to remove and contain contaminated groundwater in the shallow aquifer. Additional extraction wells may be needed. OCWD will also construct pipelines to bring the contaminated groundwater to a centralized treatment plant where the contaminants will be removed. The purified water will then be re-injected back into the shallow aquifer. An overview of the VOC plumes and the is shown in Figure 5-13. OCWD has initiated legal action against the parties responsible for contamination to seek cost recovery so that the public does not have to pay for this project. FIGURE 5-13 NORTH BASIN GROUNDWATER PROTECTION PROJECT 5.8.2 SOUTH BASIN GROUNDWATER PROTECTION PROJECT The District has initiated the a project similar to the to protect drinking water supplies in the south part of the Orange County groundwater basin. OCWD constructed six tri-nested monitoring wells to investigate the extent of VOC- contaminated groundwater in the Shallow Aquifer. Delineation of the contaminated groundwater will likely involve more than one phase of investigation. If “hot spots” or contaminated plumes are identified, the may include comprehensive remediation systems to contain and remove the contamination similar to the or GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-25 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT localized interim remedial measures. The study area for the is shown in Figure 5-14. FIGURE 5-14 SOUTH BASIN GROUNDWATER PROTECTION PROJECT 5.8.3 MTBE REMEDIATION In 2003, OCWD filed suit against numerous oil and petroleum-related companies that produce, refine, distribute, market, and sell MTBE and other oxygenates. The suit seeks funding from these responsible parties to pay for the investigation, monitoring, and removal of oxygenates from the basin. Treatment technologies used to remove MTBE from groundwater include granular activated carbon (GAC) or advanced oxidation. Depending upon site-specific requirements, a treatment train of two or more technologies in series may be 5-26 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT appropriate use one technology to remove the bulk of MTBE and a follow-up technology to polish the effluent water stream). If other contaminants excessive nitrates or TDS) are also found in groundwater with MTBE, additional treatment processes (ion exchange membranes) would also need to be included in the process train. 5.8.4 IRVINE DESALTER The Irvine Desalter was built in response to the discovery in 1985 of VOCs beneath the former El Toro MCAS and the central area of Irvine. The plume of improperly disposed cleaning solvents migrated off base and threatened the main basin. IRWD and OCWD cooperated in building production wells, pipelines, and two treatment plants, both of which are now owned and managed by IRWD. One plant removes VOCs by air- stripping and vapor-phase carbon adsorption with the treated water used for irrigation and recycled water purposes. A second plant treats groundwater outside the plume to remove excess nitrate and TDS concentrations using RO membranes for drinking water purposes. Combined production of the Irvine Desalter wells is approximately 8,000 afy. 5.8.5 TUSTIN DESALTERS Tustin’s Main Street Treatment Plant has operated since 1989 to reduce nitrate levels from the groundwater produced by Tustin’s Main Street Wells Nos. 3 and 4. The untreated groundwater can undergo either RO or ion exchange treatment. The RO membranes and ion exchange unit operate in a parallel treatment train. Approximately 1 mgd is bypassed and blended with the treatment plant product water to produce up to 2 mgd or 2,000 afy. During fiscal year 2007-08, 55,700 pounds of nitrate were removed at this treatment plant. The Tustin Seventeenth Street Desalter began operation in 1996 to reduce high nitrate and TDS concentrations from the groundwater pumped by Tustin’s Seventeenth Street Wells Nos. 2 and 4 and Tustin’s Newport well. The desalter utilizes two RO membrane trains to treat the groundwater. The treatment capacity of each RO train is 1 mgd. Approximately 1 mgd is bypassed and blended with the RO product water to produce up to 3 mgd or 3,000 afy. During fiscal year 2007-08, 154,800 pounds of nitrate were removed at this treatment facility. 5.8.6 GARDEN GROVE NITRATE REMOVAL The Garden Grove Nitrate Removal Project was a blending project utilizing two wells in order to meet the MCL for nitrate. Garden Grove Well No. 28, containing high nitrate concentrations, was blended with water from Well No. 23. The blending project operated from 1990 to 2005. The city took the well off line and is considering construction of upgraded treatment facilities to expand the pumping of groundwater in this area. 5.8.7 RIVER VIEW GOLF COURSE VOC contamination, originating from an upgradient source, was discovered in a well owned by River View Golf Course, located in the City of Santa Ana. The well was used GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-27 ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT for drinking water but was converted into a supply for golf course irrigation due to the contamination. Continued operation of the well helps to remove VOC contamination from the basin. 5.8.8 COLORED WATER TREATMENT The 5-mgd MCWD ozone oxidation treatment plant removes the color from groundwater pumped from Well No. 6 and Well No. 11. One of the ozone by-products is assimiable organic carbon (AOC), which increases the microbiological regrowth potential within the distribution system. Pressurized biologically-active filtration is employed immediately after ozone oxidation in order to remove AOC and produce microbiologically stable water. In order to meet the stringent disinfection by-products MCLs, chloramination (a combination of chlorine and ammonia) is used to disinfect the product water prior to delivery to distribution system. IRWD’s DATS removes color from deep aquifer groundwater. A total of 8 mgd of colored groundwater is pumped from two wells (IRWD C8 and C9) to the DATS plant. Nanofiltration (NF) membranes remove color and organics. Three NF trains each produce 2.44 mgd at a recovery rate of 92 percent. The high quality NF product water is degasified, disinfected, and pumped into the Dyer Road Wellfield pipeline for potable use resulting in 7.4 mgd added to the drinking water system. The highly colored NF concentrate is sent to disposal by OCSD. The colored water treatment projects operated by MCWD and IRWD provide benefit beyond the production of water supply. The aquifers with colored water are generally deeper than the primary clear water production zones, and upward vertical migration of the colored water into the clear water aquifers has been observed. Upward migration can impair water quality in the clear water zones. A large groundwater level difference between the colored water aquifer and clear water aquifers exacerbates this situation. By pumping from the colored water aquifer, the MCWD and IRWD projects reduce the groundwater level in the colored water aquifer, thus reducing the vertical migration of colored water into the clear water aquifers. 5.9 BEA Exemption for Improvement Projects In some cases, the District encourages the pumping of groundwater that does not meet drinking water standards in order to protect water quality. This is achieved by using a financial incentive called the BEA Exemption. The benefits to the basin include removing and beneficially using poor-quality groundwater and reducing or preventing the spread of poor-quality groundwater into non-degraded aquifer zones. As explained in detail in Section 6, OCWD uses financial incentives to manage the level of pumping from the groundwater basin. Producers pay a Replenishment Assessment (RA) for water pumped from the basin. Each year the District sets an allowable amount of pumping and assesses an additional charge, called the BEA, on all water pumped above that limit. A BEA Exemption is used to encourage pumping of groundwater that does not meet drinking water standards in order to clean up and contain the spread of poor quality 5-28 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 5-29 water. Section 38.1 of the District Act provides specific criteria for exemption of the BEA: “If the board of directors finds and determines that the water produced from the facility or facilities or any of them has or will have a beneficial effect upon the quality of water supplies of the district, the board of directors may make an order that water produced from the water-producing facility or facilities shall be exempted from either or both of the following: The payment of all or any portion of the basin equity assessment… The production requirements and limitations as provided in this act.” OCWD uses a partial or total exemption of the BEA to compensate a qualified participating agency or Producer for the costs of treating poor-quality groundwater. These costs typically include capital, interest, and operations and maintenance (O&M) costs for the treatment facilities. Under this provision, the District has exempted all or a portion of the BEA for pumping and treating groundwater for removal of nitrates, TDS, VOCs, and other contaminants. Water quality improvement projects that have received a BEA exemption are listed in Table 5-6. When the District authorizes a BEA exemption for a project, OCWD is obligated to provide the replenishment water for the production above the BPP and forgoes the BEA revenue that OCWD would otherwise receive from the producer. TABLE 5-6 SUMMARY OF IMPROVEMENT PROJECTS AND REPLENISHMENT OBLIGATIONS Project Name Project Description BEA Exemption Approval Date Groundwater Production above BPP (afy) OCWD Subsidy Irvine Desalter Removal of nitrates, TDS, and VOCs 2001 10,000 BEA Exemption Tustin Desalter Removal of nitrates and TDS 1998 3,500 BEA Exemption Garden Grove Nitrate Blending two Garden Grove wells to meet nitrate MCL 1998 4,000 BEA Exemption Tustin Nitrate Removal Removal of nitrates 1998 1,000 BEA Exemption River View Golf Course Removal of VOCs 1998 350 $50/af reduction in BEA MCWD Colored Water Removal Color removal 2000 8,700 BEA Exemption IRWD DATS Color removal 1999 8,000 BEA Exemption ---PAGE BREAK--- SECTION 5 WATER QUALITY MANAGEMENT 5-30 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE This page left blank intentionally ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE The District operates the groundwater basin in order to protect and increase the basin’s sustainable yield in a cost effective manner. Accomplishing this goal requires careful management of recharge and water production. This section describes the methods and programs utilized by OCWD to maintain the long-term sustainability of the basin’s groundwater supplies. 6.1 General Management Approach OCWD is internationally known for its unique, proactive, supply-side management approach. This is a major factor that has enabled the District to develop one of the most advanced and progressive groundwater management systems in the world. The District seeks to expand the basin’s yield by maximizing the amount of water recharged into the basin, developing new sources of water to recharge the basin, and increasing the effectiveness of the District’s recharge facilities. OCWD provides access to basin supplies at a uniform cost to all entities within the District without regard to the length of time they have been producing from the basin. After initiating this policy in 1954 with the establishment of the Replenishment Assessment (RA), OCWD witnessed a substantial growth in municipal and industrial water usage. This growth has not occurred without its accompanying challenges to OCWD: the need to augment recharge water supplies, establish methods to effectively manage demands on the basin, and balance the amount of total recharge and total pumping to protect the basin from being overdrafted. The District’s participation in a wide range of cooperative efforts with other water and waste water agencies as well as stakeholder organizations plays an important part in the management of the groundwater basin. 6.2 Cooperative Efforts to Protect Water Supplies and Water Quality OCWD participates in cooperative efforts with state and federal regulatory agencies and stakeholders within the District boundaries, in Orange County, and in the Santa Ana River Watershed. 6.2.1 SANTA ANA WATERSHED PROJECT AUTHORITY (SAWPA) SAWPA is a Joint Powers Authority whose mission is to develop and maintain regional plans, programs, and projects that will protect the Santa Ana River basin water resources. OCWD, one of SAWPA’s five member agencies, actively participates on a number of work groups that meet on a regular basis to discuss, plan, and make joint decisions on management of water resources in the Santa Ana Watershed. OCWD actively participates in the following SAWPA work groups: GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-1 ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE SAWPA Commission: The commission, composed of Board members from SAWPA’s five member agencies including OCWD, meets on a basis to set policy and oversee the management of SAWPA. Storm Water Quality Standards Task Force: The Task Force is evaluating water quality standards as they relate to stormwater and dry weather flows. Particular emphasis is being given to the water quality that is needed to protect recreational beneficial uses. Basin Monitoring Program Task Force: The Basin Monitoring Program Task Force was formed in 1995 to determine the extent of and evaluate the impact of increasing concentrations of Total Inorganic Nitrogen (TIN) and TDS in groundwater in the watershed. Formation of the Task Force was in response to concerns by the Regional Board that water quality objectives for nitrogen and TDS were being exceeded in some groundwater basins in the watershed. The over 20 water and waste water agencies and local governments on the Task Force worked with staff to develop an amendment to the Water Quality Control Plan for the Santa Ana River Basin (Basin Plan) that was adopted in 2004. This nearly ten-year effort involved collecting and analyzing data in twenty-five groundwater management zones in the watershed to recalculate nitrogen and TDS levels and to establish new Water Quality Objectives to protect Beneficial Uses. An important component in this effort was the recognition by stakeholders that groundwater basins are interconnected and that water quality in one basin impacts other basins and the quality of the water in the Santa Ana River. The Basin Plan amendment charges the Task Force with implementing a watershed-wide TDS/Nitrogen groundwater monitoring program. Task Force members agreed to fund and participate in a process to recalculate ambient water quality every three years in each of the twenty-five groundwater management zones and to compare water quality to the water quality objectives in order to measure compliance with the Basin Plan. The latest recalculation, the second since adoption of the amendment, was published in August 2008 (Wildermuth, 2008). Salinity Management and Imported Water Recharge Plenary Workgroup: This workgroup, in cooperation with the Regional Board, implements a Cooperative Agreement signed by water agencies that use imported water for groundwater recharge. The workgroup is analyzing water quality data and estimating future conditions to evaluate the impact of recharging imported water. Emerging Constituents Workgroup: This workgroup is developing a monitoring program for emerging constituents in water that is intentionally recharged to local aquifers. The group will develop a 6-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE water quality monitoring program aimed at protecting surface water quality and groundwater supplies. Santa Ana Sucker Conservation Team: Meeting since 1998, a group of concerned public agencies from throughout the Santa Ana River watershed have been working to determine the reasons for the decline of the Santa Ana Sucker (Catostomus santaanae) and to devise strategies for recovering the species. The U.S. Fish & Wildlife Service (USFWS) and the California Department of Fish & Game (CDFG) are part of this effort. One Water One Watershed Initiative: A large and diverse group of interested citizens and organizations is participating in developing an updated Santa Ana Watershed Integrated Regional Water Management Plan. 6.2.2 WATER QUALITY AND NATURAL RESOURCE PROTECTION IN THE PRADO BASIN The water quality of the Santa Ana River and its tributary creeks has a direct impact on the quality of water that flows into Orange County. The operation of the Prado Wetlands, as described in Section 5.3.3, improves water quality through the removal of nitrates and other pollutants before the water reaches OCWD’s groundwater recharge basins. The Prado Basin contains the single largest stand of forested riparian habitat remaining in coastal southern California. The basin provides a variety of fish and bird habitats including several rare and endangered species. OCWD manages a large portion of this property and has undertaken numerous habitat restoration and species recovery projects. As part of a cooperative agreement with the ACOE and the USFWS, OCWD has created more than 800 acres of habitat for the endangered least Bell’s vireo and southwestern willow flycatcher and has funded more than $3 million in mitigation and monitoring measures for the vireo program. Through these restoration activities, OCWD has made significant contributions towards the recovery of vireo. In the mid-eighties, the vireo population had dropped to less than 20 breeding pairs. A 2007 survey identified 420 vireo territories, 237 of which contained pairs. Plans are underway to create additional river edge habitat, the preferred habitat of the flycatcher, in order to increase the population of this endangered bird. A significant amount of the Prado Basin is infested with exotic vegetation, including the Giant Reed (Arundo donax), shown in Figure 6-1. Arundo grows rapidly, obstructs flood flows, has no value for wildlife habitat, and consumes nearly three times the water of native vegetation. Arundo consumes an estimated 56,200 af of water annually from the Santa Ana River. OCWD has invested over $3 million in Arundo removal efforts. These efforts are coordinated by the Santa Ana Watershed Association (SAWA). The SAWA, of which OCWD is a founding member, is dedicated to improving environmental quality and habitat within the watershed. Other members of SAWA include the CDFG, Riverside GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-3 ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE County Flood Control District, Riverside County Parks and Recreation, San Bernardino County Flood Control District, SAWPA, the the ACOE, the USFWS, and the U.S. Forest Service. Approximately 3,100 acres of river bottom lands formerly infested by Arundo and other invasive weeds are now under management. It is estimated that by 2025, an annual minimum of 36,000 af of additional water will be available in the Santa Ana River as a result of removing Arundo (based on a minimum of 3.6 af of additional water per acre of Arundo removed). FIGURE 6-1 ARUNDO REMOVAL Arundo Control Begins with Removal by Hand or Machine Followed by Treatment of Re-growth with a Systemic Herbicide 6.2.3 CHINO BASIN INTEGRATED PLANNING Chino Creek and Mill Creek are major tributaries that flow into the Santa Ana River in the Prado Basin. OCWD staff attends meetings of stakeholders from this region to discuss and act upon issues of common concern. In 2006, the group, led by the IEUA and OCWD produced the Chino Creek Integrated Plan: Guidance for Working Together to Protect, Improve, and Enhance the Lower Chino Creek Watershed. 6.2.4 COOPERATIVE EFFORTS IN ORANGE COUNTY OCWD supports the watershed planning efforts of the County of Orange. The county created three watershed management areas in order to localize the development and implementation of integrated regional watershed plans. Two of the management areas are within the OCWD service area. The North Orange County Management Area covers the areas within the county that are located within the Santa Ana River Watershed and the coastal watersheds west of the Santa Ana River. The Central Orange County Management Area covers the Newport Bay Watershed and the Newport Coast area. OCWD participates in the development and implementation of the North Orange County and Central Orange County watershed plans. 6-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE 6.2.5 COOPERATIVE EFFORTS IN OCWD SERVICE AREA OCWD participates in a variety of cooperative efforts with water retailers and cities within the OCWD service area as well as wastewater and flood control agencies, as described below. Groundwater Producers The Producers, the retail water agencies that produce the majority of the groundwater from the basin, meet with OCWD staff on a basis to discuss issues related to management of the groundwater basin. Municipal Water District of Orange County (MWDOC) MWDOC, a member agency of the Metropolitan Water District of Southern California, provides imported water to 28 retail water agencies and cities in Orange County. MWDOC also supplies untreated imported water to OCWD when it is available for use as a supplemental source of water to recharge the groundwater basin. OCWD and MWDOC meet on a basis and jointly plan for the maximum flexibility in the overall water supply, including: • Coordinating mutual water resources planning, supply availability, and water use efficiency (conservation) programs for the benefit of the basin area in Orange County. • Conducting and developing an Orange County Water Reliability Program to improve the overall water and emergency supply to Orange County. • Evaluating ocean water desalination, water recycling, and other means to increase the supply and system reliability for the basin area. • Evaluating water transfers and exchanges that would make surplus supplies from other areas available to the District. Water Advisory Committee of Orange County (WACO) WACO is a group of elected officials and water managers who meet on a basis to provide advice to OCWD and MWDOC on water supply issues. Groundwater Replenishment System Steering Committee The GWR System is a joint project of the OCWD and the Orange County Sanitation District. Directors of the two districts meet on a basis to coordinate joint operations. Orange County Flood Control District Three of the recharge basins used by OCWD for groundwater recharge are owned by the Orange County Flood Control District. OCWD also owns a six-mile section of the Santa Ana River that is used for conveyance of flood water. Quarterly meetings are held to discuss joint operations and planning. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-5 ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE 6.3 Supply Management Strategies One of OCWD’s management objectives is to maximize the amount of water recharged into the basin. This is achieved through maximizing the efficiency of and expanding the District’s recharge facilities and increasing the supply of recharge water. The District constructed the GWR System to increase the supply of water available to recharge the basin. Additional District supply management programs include encouraging and using recycled water for irrigation and other non-potable uses, participating in water conservation efforts, participating in efforts to manage water and other natural resources in the upper watershed, and working with MWDOC in developing and conducting other supply augmentation projects and strategies. 6.3.1 USE OF RECYCLED WATER OCWD’s Green Acres Project is a non-potable water supply project that utilizes a dedicated set of pipelines to deliver irrigation and industrial water to users. Most of the recycled water is used on golf courses, greenbelts, cemeteries, and nurseries. The Green Acres Project, in operation since 1991, reduces demands on the basin by providing non-potable water for non-potable uses. Secondary wastewater effluent from the OCSD is filtered and disinfected with chlorine to produce approximately seven mgd of irrigation and industrial water. 6.3.2 WATER CONSERVATION PROGRAMS Water conservation plays an important role in meeting future water demands. By implementing conservation programs, future water demand can be reduced, and less imported water will be necessary to meet the area’s water requirements. The District cooperated with MWDOC, OCSD, and other agencies in a low-flush toilet program that subsidized the replacement of old high-volume toilets with modern low- flow toilets. The District also supports MWDOC and Metropolitan in a Hotel/Motel Water Conservation Program to save water through minimizing water use at hotels. This program, active in over 30,000 hotel/motel rooms, offers free laminated towel rack hangers or bed cards that encourage guests to consider using their towels and bed linens more than once during their stay. OCWD supports MWDOC and other local agencies in a similar program aimed at restaurant water conservation. Free laminated cards are provided for restaurants to place on their tables. The cards inform patrons that water will be served only upon request. This encourages environmental awareness and water and energy conservation. 6.3.3 CONJUNCTIVE USE AND WATER TRANSFERS The existing Metropolitan storage program provides for Metropolitan to store 66,000 af of water in the basin in exchange for Metropolitan’s contribution to improvements in basin management facilities. This water can be withdrawn over a three-year time period. The improvements contributed by Metropolitan included the construction of eight new extraction wells and new injection wells for the Talbert Barrier Expansion. 6-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE The District reviews opportunities for additional conjunctive use projects that would store water in the basin and could potentially store water in other groundwater basins. Additionally, the District reviews opportunities for water transfers that could provide additional sources of recharge water. Such projects are evaluated carefully with respect to their impact on available storage and their reliability and cost effectiveness. 6.4 Water Demands Numerous factors influence water demands such as population growth, economic conditions, conservation programs, and hydrologic conditions. Estimates of future demands are therefore subject to some uncertainty and are updated on a periodic basis. Total water demand within the District’s boundary for water year 2007-08 (July 1- June 30) was 480,303 af. Total demand is met with a combination of groundwater, imported water, local surface water in Irvine Lake and Santiago Creek, and recycled water used for irrigation and industrial purposes. Figure 6-2 provides historical water demands in the District. s. Figure 6-2 provides historical water demands in the District. FIGURE 6-2 FIGURE 6-2 HISTORICAL TOTAL DISTRICT WATER DEMANDS HISTORICAL TOTAL DISTRICT WATER DEMANDS 0 100,000 200,000 300,000 400,000 500,000 600,000 1984-85 1985-86 1986-87 1987-88 1988-89 1989-90 1990-91 1991-92 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 Water Year Acre-Feet GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-7 ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE Demand estimates are based on a number of factors including projected population increases. Population within OCWD’s service area is expected to increase from 2.5 million currently to 2.7 million by the year 2035 as shown in Table 6-1. This population growth is expected to increase water demands from the current approximately 480,000 afy to 558,000 afy in 2035 as shown in Table 6-2. Future annual water demands will fluctuate, primarily due to factors such as the effectiveness of future water conservations programs, economic conditions, and hydrologic conditions. TABLE 6-1 ESTIMATED POPULATION WITHIN OCWD BOUNDARY 2010 2015 2020 2025 2030 2035 2,550,000 2,620,000 2,659,000 2,685,000 2,703,000 2,722,000 Source: MWDOC and Center for Demographics Research (2008) TABLE 6-2 ESTIMATED FUTURE WATER DEMANDS IN OCWD BOUNDARY (AFY) 2009 2010 2015 2020 2025 2030 2035 490,000 500,000 519,000 538,000 548,000 553,000 558,000 Projections based on annual MWDOC survey completed by each Producer - Spring 2008 Expansion of the District’s boundary through annexing additional land into the District has been a major factor in the growth of OCWD. From 1933 to now, the District’s area has grown from 162,676 acres to over 229,000 acres (OCWD, 2006). Annexation requests by the City of Anaheim, Irvine Ranch Water District, and Yorba Linda Water District, if approved, could expand the District’s boundary and increase water demands by approximately 48,000 afy. 6.5 Basin Operating Range OCWD does not regulate pumping from the groundwater basin. Instead, total pumping is managed by a process that uses financial incentives to encourage Producers to pump an aggregate amount of water that is sustainable over the long term. The process that determines a sustainable level of pumping considers the basin’s safe operating range and the amount of recharge water available to the District. The basin operating range refers to the upper and lower levels of groundwater storage in the basin that can be reached without causing negative or adverse impacts. The basin is in the upper (higher) end of the operating range when groundwater levels are high. Conversely, the basin is near the low end of the operating range when groundwater levels are lower. Figure 6-3 schematically illustrates the impacts of changing the amount of groundwater in storage. 6-8 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE The storage level is quantified based on a benchmark defined as the full basin condition. The groundwater basin rarely, if ever, reaches the full basin condition. The degree to which the storage is below the full basin condition is defined as “accumulated overdraft.” Based on this definition of accumulated overdraft, it is anticipated that the accumulated overdraft would increase or decrease from year to year in response to hydrological variations. Provided that the accumulated overdraft is within the safe operating range, this approach is sustainable. FIGURE 6-3 SCHEMATIC ILLUSTRATION OF IMPACTS OF CHANGING THE AMOUNT OF GROUNDWATER IN STORAGE Land Surface Effects of Decreased Overdraft: • More water available in storage to be pumped during drought • Increased loss of water to LA County • Decreased opportunity to recharge basin if large amounts recharge water becomes available • Beneficial in controlling seawater intrusion • Decreased pumping costs Decreased overdraft (increased water in storage) Ocean Increased overdraft (decreased water in storage) Effects of Increased Overdraft: • Less water available in storage to be pumped during drought • Decreased loss of water to LA County • Increased available storage capacity if large amounts recharge water becomes available • Increased potential for seawater intrusion (if exceed barrier threshold) • Increased pumping costs • Increased potential for inflow of colored water into clear water aquifers • Increased potential for land subsidence (if exceed threshold) • May need to increase budget for replenishment water to reduce overdraft • Some shallow production wells may become inoperable due to low groundwater levels Land Surface Effects of Decreased Overdraft: • More water available in storage to be pumped during drought • Increased loss of water to LA County • Decreased opportunity to recharge basin if large amounts recharge water becomes available • Beneficial in controlling seawater intrusion • Decreased pumping costs Decreased overdraft (increased water in storage) Ocean Increased overdraft (decreased water in storage) Effects of Increased Overdraft: • Less water available in storage to be pumped during drought • Decreased loss of water to LA County • Increased available storage capacity if large amounts recharge water becomes available • Increased potential for seawater intrusion (if exceed barrier threshold) • Increased pumping costs • Increased potential for inflow of colored water into clear water aquifers • Increased potential for land subsidence (if exceed threshold) • May need to increase budget for replenishment water to reduce overdraft • Some shallow production wells may become inoperable due to low groundwater levels Each year the District determines the optimum level of storage for the following year. For example, at small amounts of overdraft (greater total amount of water in storage), the amount of energy required to pump groundwater is less and groundwater outflow to Los Angeles County is greater. On the other hand, larger amounts of overdraft increase the potential for seawater intrusion. Factors that are considered in determining the optimum level of storage are shown in Table 6-3. The accumulated overdraft is calculated and published in the annual District’s Engineer’s Report. Since 2007, the determination of accumulated overdraft is based on a full basin benchmark defined for each of the three aquifer layers as described in Section 2. The shallow aquifer, the principal aquifer, and the aquitard between the shallow and principal aquifer stores approximately 66,000,000 af of water at the full condition. When the accumulated overdraft is 200,000 af, the Basin is approximately 99.7 percent full. When the overdraft increases from 200,000 to 400,000 af, the basin changes from 99.7 to 99.4 percent full. From a classical surface water reservoir perspective, the basin is GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-9 ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE almost always nearly “full.” In spite of the large amount of water stored in the basin, there is a narrow operating range within which the Basin can safely operate, as illustrated in Figure 6-4, which is largely dictated by water quality issues and the need to prevent land subsidence. TABLE 6-3 BENEFITS AND DETRIMENTS OF DIFFERENT STORAGE LEVELS ACCUMULATED OVERDRAFT (AF) BENEFITS DETRIMENTS Less than 200,000 • Beneficial to controlling seawater intrusion • Lower pumping energy costs for producers • Easier to maintain stable BPP • Water available to be pumped from storage in shortage condition • Potential to temporarily increase BPP • Decreased potential for vertical migration of poor quality water • Opportunity to operate Basin to build reserves • Increased loss of groundwater to Los Angeles County • Possible localized high groundwater levels if near full condition • Decreased opportunity to recharge Basin if large amount of low cost recharge water becomes available • Possible decrease in recharge capacity due to high groundwater levels (not observed at current recharge rates, but may be an issue with higher rates in future) 200,000 to 350,000 • Minimal to no problems with high groundwater levels • Increased available storage capacity if large amount of recharge water becomes available • Decreased groundwater outflow to Los Angeles County • Limited amount of water in storage that can be pumped during drought or other shortage condition • Risk of seawater intrusion increases as overdraft increases from 200,000 to 350,000 af • Option for Metropolitan to call 20,000 afy from storage would further increase overdraft 350,000 to 500,000 • Minimal to no problems with high groundwater levels • Increased available storage capacity if large amount of recharge water becomes available • Further decrease in groundwater outflow to Los Angeles County • Little to no water in storage that can be pumped during drought or other shortage condition • Increased pumping energy costs • Further increased risk of seawater intrusion • Coastal pumping reductions potentially needed • Option for Metropolitan to call 20,000 afy from storage further worsens overdraft • Increased number of production wells inoperable due to low groundwater levels below 400,000 af overdraft • Potential risk of increased land subsidence • Potential increased risk of vertical migration of poor quality water. • Need to increase budget for replenishment water to reduce overdraft • More difficult to maintain stable BPP 6-10 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE FIGURE 6-4 STRATEGIC BASIN OPERATING LEVELS AND OPTIMAL TARGET - 500,000 AF - 434,000 AF - 100,000 AF 0 AF Overdraft 66,000 AF MWD storage Full Condition Storage capacity for one wet year Optimal Target OCWD Operating Range Provides at least three years of drought supply when at top of range Lowest Acceptable Level - 500,000 AF - 434,000 AF - 100,000 AF 0 AF Overdraft 66,000 AF MWD storage Full Condition Storage capacity for one wet year Optimal Target OCWD Operating Range Provides at least three years of drought supply when at top of range Lowest Acceptable Level Groundwater levels must be carefully managed to properly control seawater intrusion. With the water available for injection from the GWR System, seawater intrusion may be controlled in the Talbert Gap with a maximum overdraft of 500,000 af. Improvements to the Talbert Barrier may allow greater overdraft but the impact of greater withdrawals on the other gaps, Bolsa, Sunset and Alamitos, must also be evaluated. Additional issues that would need to be evaluated prior to increasing the amount of overdraft, assuming an effective seawater barrier was operating, would include the risk of land subsidence, inflow of colored water or poor quality groundwater into the principal aquifer from underlying or overlying aquifers, and the number of shallow production wells that would become inoperable due to lower groundwater levels. 6.6 Balancing Production and Recharge Over the long term, the basin must be maintained in an approximate balance to ensure the long-term viability of basin water supplies. In one particular year, water withdrawals may exceed water recharged as long as over the course of a number of years this is GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-11 ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE balanced by years where water recharged exceeds withdrawals. Levels of basin production and water recharged since water year 1991-92 are shown in Figure 6-5. FIGURE 6-5 BASIN PRODUCTION AND RECHARGE SOURCES - 100,000 200,000 300,000 400,000 500,000 600,000 91-92 92-93 93-94 94-95 95-96 96-97 97-98 98-99 99-00 00-01 01-02 02-03 03-04 04-05 05-06 06-07 07-08 Water Year AFY SAR Baseflow Natural Incidental Recharge Captured SAR Stormflow Imported Water/GWR System Groundwater Production Water Year SAR Baseflow Natural Incidental Recharge Captured SAR Stormflow Imported Water/ GWR System Groundwater Production 91-92 105,000 2,000 65,000 109,000 311,000 92-93 127,000 107,000 111,000 82,000 312,000 93-94 114,000 78,000 41,000 144,000 312,000 94-95 120,000 70,000 117,000 44,000 314,000 95-96 128,000 58,000 70,000 32,000 329,000 96-97 138,000 74,000 51,000 56,000 339,000 97-98 146,000 101,000 74,000 55,000 329,000 98-99 161,000 36,000 50,000 35,000 356,000 99-00 150,000 82,000 33,000 84,000 384,000 00-01 153,000 50,000 27,000 95,000 369,000 01-02 150,000 38,000 21,000 73,000 374,000 02-03 143,000 58,000 52,000 109,000 359,000 03-04 146,000 59,000 39,000 84,000 337,000 04-05 149,000 159,000 85,000 87,000 314,000 05-06 153,000 39,000 84,000 104,000 318,000 06-07 133,000 15,000 19,000 103,000 350,000 07-08 132,000 52,000 46,000 30,000 368,000 6-12 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-13 6.7 Managing Basin Pumping The primary mechanism used by OCWD to manage pumping is the Basin Production Percentage (BPP). Section 31.5 of the District Act empowers the Board to annually establish the BPP, defined as: “the ratio that all water to be produced from groundwater supplies with the district bears to all water to be produced by persons and operators within the District from supplemental sources as well as from groundwater within the District. “ In other words, the BPP is a percentage of each Producer’s water supply that comes from groundwater pumped from the basin. The BPP is set uniformly for all Producers. Groundwater production at or below the BPP is assessed the RA. Any production above the BPP is charged the RA plus the BEA. The BEA is calculated so that the cost of groundwater production above the BPP is higher than purchasing imported potable supplies. This approach serves to discourage, but not eliminate, production above the BPP. The BEA can be increased as needed to discourage production above the BPP. In simplified terms, the BPP is calculated by dividing groundwater production by total water demands. The BPP is set after evaluating groundwater conditions, availability of recharge water supplies, and basin management objectives. The BPP is also a major factor in determining the cost of groundwater production for that year. OCWD’s goal is to set the BPP as high as possible to allow Producers to maximize pumping and reduce their overall water supply cost. Figure 6-6 shows the history of the BPP along with the actual BPP that was achieved by the Producers. FIGURE 6-6 BASIN PRODUCTION PERCENTAGE HISTORY OCWD Assigned Basin Production Percentage Water Year 0% 20% 40% 60% 80% 100% In-Lieu Groundwater 1984-85 1985-86 1986-87 1987-88 1988-89 1989-90 1990-91 1991-92 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 Achieved Production Percentage ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE 6-14 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Raising or lowering the BPP allows the District to manage the amount of pumping from the basin. The BPP is lowered when basin conditions necessitate a decrease in pumping. A lower BPP results in the need for Producers to purchase additional, more expensive imported water from Metropolitan. One example of a condition that could require a lowering of the BPP is to protect the basin from seawater intrusion. In this case, reduced pumping would allow groundwater levels to recover and seawater intrusion to be reduced. A change in the BPP affects the District’s budget as less pumping reduces collected revenues. 6.7.1 METHODOLOGY FOR SETTING THE BASIN PRODUCTION PERCENTAGE The formula used to estimate the BPP is shown in Figure 6-7. The formula is used as a guideline and the District’s Board of Directors sets the BPP after considering the relevant information and input from the Producers and the public. To determine the BPP for a given year the amount of water available for basin recharge must be estimated. The supplies of recharge water that are estimated are: • Santa Ana River stormflow • Natural incidental recharge • Santa Ana River baseflow • GWR System supplies • Other supplies such as Metropolitan and recycled water purchased for the Alamitos Barrier. FIGURE 6-7 BPP CALCULATION MWD = Metropolitan Water District of Southern California SAR Stormflows using Rainfall Probability Natural Incidental Recharge using Rainfall Probability SAR Baseflows (5-yr Avg) Expected MWD Replenishment Water Expected GWR System Supplies Other expected supplies such as Alamitos Barrier and Arlington Desalter Expected WQ pumping above BPP Planned Basin Refill (from table) BPP = + + - - Total Water Demands (5-yr Avg.) Expected Reclaimed & Local Supplies - + + + ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE Probability factors are used to estimate recharge into the groundwater basin from Santa Ana River stormflow and natural incidental recharge. The probability percentages are based on over 100 years of rainfall data and represent the probability that the upcoming year will not be drier than the predicted rainfall amount. As the accumulated overdraft increases, a higher level of certainty or probability is used in the BPP calculation to ensure that the basin recharge estimates are attained or exceeded. For example, if the accumulated overdraft is 500,000 af, then a 90 percent rainfall probability would be used to conservatively estimate that the upcoming year’s rainfall will only be nine inches even though there is a 90 percent chance that it will be greater. With this methodology, there is 90 percent likelihood that the upcoming year’s estimate of rainfall will be exceeded. When the basin is nearly full, the ten percent probability of expected rainfall would be used. In other words, it would be determined that there is only a ten percent chance of having an upcoming year that is wetter than assumed, or conversely, a 90 percent chance that the upcoming year will be drier. For the San Bernardino rainfall station, the ten percent rainfall exceedance probability is 27 inches of rainfall. Therefore, assuming 27 inches of rainfall for the upcoming year’s BPP calculation would ensure with 90 percent likelihood that it would actually be drier, less water would be recharged into the basin, and the accumulated overdraft would be increased so as to prevent overfilling the basin and losing water to the ocean. When the basin is within the optimal range of 100,000 to 150,000 af of accumulated overdraft, the 50 percent probability of rainfall is suggested to be used. In other words, there would be an equal chance (50/50) of having either a wetter or drier year than assumed. In this case, the 50 percent rainfall exceedance probability is very similar to assuming average hydrology for the upcoming year. This methodology provides a guideline for the upcoming year’s recommended amount of basin refill, dependent of the level of accumulated overdraft. For each increasing level of accumulated overdraft, an increasing amount of basin refill is suggested, ranging from approximately five to ten percent of the accumulated overdraft. For example, at an accumulated overdraft level of 400,000 af, the suggested amount of basin refill or overdraft reduction for the upcoming year would range from 20,000 to 40,000 af. Therefore, at this assumed basin refill rate, it would take approximately 10 to 20 years to completely fill the basin and eliminate the overdraft. Table 6-4 shows the established amount or range for the planned basin refill water (reduction to the basin’s accumulated overdraft) that is used in the formula based upon the basin’s accumulated overdraft. The range is based upon provisions in the District Act which call for refilling the groundwater basin in not less than 10 years and not greater than 20 years. For example; if the accumulated overdraft is 400,000 af, refilling the basin over a 20-year period would yield a value of 20,000 afy while refilling the basin over a 10-year period yields a value of 40,000 afy. GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-15 ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE TABLE 6-4 ACCUMULATED OVERDRAFT, BASIN REFILL, PROBABILITY FACTOR & RAINFALL AMOUNT Accumulated Overdraft (af) Planned Basin Refill Amount (af) San Bernardino Rainfall Projection (inches) Probability Factor 0 -20,000 27 10% 100,000 0 15 50% 200,000 10,000 to 20,000 14 60% 300,000 15,000 to 30,000 13 70% 400,000 20,000 to 40,000 11 80% 500,000 25,000 to 50,000 9 90% For the 2008-09 water year, the estimated supply of recharge water is summarized in Table 6-5. TABLE 6-5 RECHARGE WATER SUPPLIES ESTIMATED FOR 2008-09 Source Amount (afy) Santa Ana River Baseflows 146,300 Captured Santa Ana River Stormflows 50,000 Natural Net Incidental Recharge 60,000 Expected Groundwater Replenishment Supplies 61,000 Other Expected Supplies 11,000 Total 328,300 6.7.2 BASIN PRODUCTION LIMITATION Another management tool that enables OCWD to sustainably manage the basin is the Basin Production Limitation. Section 31.5(g) of the District Act authorizes limitations on production and the setting of surcharges when those limits are exceeded. This provision can be used when it is necessary to shift pumping from one area of the basin to another. An example of this was the Temporary Coastal Pumping Transfer Program, which shifted approximately 20,000 afy of pumping from the coastal area to inland to minimize seawater intrusion. 6.8 Drought Management Drought is an extended period of below-average precipitation. There is no single, official definition of the time period associated with a drought. The magnitude of a drought depends on the extent of the deviation from average precipitation, the areal extent of the below-average precipitation, and other factors. During a drought, flexibility to increase pumping from the basin becomes increasingly important. To the extent that the basin has water in storage that can be pumped out, the basin provides a valuable water supply asset during drought conditions. Ensuring that the basin can provide a buffer against drought conditions requires: 6-16 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 6-17 • Maintaining sufficient water in storage that can be pumped out in time of need; • Operating the basin at the lower water storage in a safe manner; and • Possessing a plan to refill the basin. The San Bernardino precipitation station data, shown in Figure 4-11, is used to evaluate the extent of droughts in the Santa Ana River watershed. This station is selected because it is used in the Santa Ana River Watermaster reports (Santa Ana River Watermaster Report, 2008) and has a relatively long period of record. During drought conditions, the District experiences a decline in the supply of recharge water. Replenishment water from Metropolitan is only available to OCWD when Metropolitan has excess supplies. In addition, the local supply of Santa Ana River recharge water and net incidental recharge water could decline up to 55,000 afy or more during drought years as shown in Table 6-6. TABLE 6-6 IMPACT OF DROUGHTS ON RECHARGE WATER SUPPLIES RECHARGE WATER SUPPLY ESTIMATED DECREASE IN SUPPLY DUE TO DROUGHT (AF/YR) Santa Ana River Baseflow 15,000 Santa Ana River Stormflow 20,000 or more Net Incidental Recharge 20,000 or more Total 55,000 or more Note: does not include potential decline in Metropolitan replenishment supplies 6.8.1 MAINTAINING WATER IN STORAGE FOR DROUGHT CONDITIONS For the basin to serve as a safe, reliable buffer, sufficient groundwater must be stored before a drought occurs. As an example, assume the basin has an accumulated overdraft of 150,000 af and can be drawn down to 500,000 af without irreparable seawater intrusion. The basin has 350,000 af of water in storage. In a hypothetical five- year drought, recharge water supplies can decrease 55,000 afy without jeopardizing the long-term health of the basin. Since recharge water supplies are likely to decline during drought years, the water stored at the beginning of the drought is critical. If water is stored in Metropolitan’s conjunctive use storage program, this stored water must also be accounted for. 6.8.2 BASIN OPERATION DURING DROUGHT When the basin overdraft is intentionally increased, the basin must be operated in a safe manner, considering the potential for land subsidence and seawater intrusion, the availability of sufficient excess recharge capacity to eventually refill the basin, the impact of low groundwater levels on shallow production wells, and a potential for ---PAGE BREAK--- SECTION 6 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE colored water to flow into clear water aquifers. Approaches for refilling the Basin are described in Table 6-7. TABLE 6-7 APPROACHES TO REFILLING THE BASIN APPROACH DISCUSSION Decrease Total Water Demands • Increase water conservation measures (note this does not result in a 1:1 decrease in groundwater pumping because some of the increased conservation reduces Metropolitan demands); this decreases pumping from the basin if the BPP is held constant and all other factors remain the same. Decrease BPP • Allows groundwater levels to recover rapidly • Decreases revenue to the District • Increases water cost for producers • Does not require additional recharge facilities • Dependent upon other sources of water water from Metropolitan) being available to substitute for reduced groundwater pumping Increase Recharge • Dependent on increased supply of recharge water • Water transfers and exchanges could be utilized to provide the increased supply of recharge water • Dependent on building and maintaining excess recharge capacity (which would be under-utilized in non-drought years) Combination of the Above • A combination of the approaches provides flexibility and a range of options for refilling the basin 6-18 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 7 FINANCIAL MANAGEMENT 7 FINANCIAL MANAGEMENT 7.1 Background Financial Information The District’s fiscal year (FY) begins on July 1 and ends on June 30. The annual operating budget for 2008-09 was approximately $116.3 million; District revenues are expected to be approximately $116.3 million. A significant increase in the budget to fund the operation of the GWR System was approved by the Board in 2007. 7.2 Operating Expenses The District’s budgeted operating expenses for FY 2008-09 are summarized in Table 7-1 and described below. TABLE 7-1 FY 2008-09 BUDGETED OPERATING EXPENSES EXPENSES AMOUNT (in millions) General Fund $57.2 Total Debt Service 28.3 Water Purchases 19.1 New Equipment/ Small Projects 2.2 Increase to Reserves 0.9 Refurbishment and Replacement Expenditures 8.6 Total $116.3 OCWD strives to improve the efficiency of all aspects of its operations in its continuing efforts to increase the water quality and reliability of Orange County’s local water resources at the lowest possible cost. The District manages its finances to provide long-term fiscal stability. To achieve this objective OCWD: • Manages finances to maintain high credit ratings. • Manages District operations efficiently and effectively. • Maintains reserves for purchase of supplemental water supplies when available. • Recovers contamination clean up costs from responsible parties when possible. • Sets the Basin Production Percentage to optimize sustainable use of groundwater. GROUNDWATER MANAGEMENT PLAN UPDATE 2009 7-1 ---PAGE BREAK--- SECTION 7 FINANCIAL MANAGEMENT 7.2.1 GENERAL FUND The District’s general fund account primarily allows the District to operate the recharge facilities in the cities of Anaheim and Orange, GWR System, the Talbert and Alamitos Injection Barriers, the Green Acres Project, and the Prado Wetlands. In addition, the District’s Water Quality Laboratory, groundwater monitoring programs, watershed management, planning, and other miscellaneous activities are funded by this account. 7.2.2 DEBT SERVICE The debt service budget provides for repayment of the District’s debt from issues of previous bonds. OCWD has a comprehensive long-range debt program, which provides for the funding of projects necessary to increase basin production and protect water quality, while providing predictable impacts to the RA. The annual project-related debt expense is approximately $28.3 million. The District holds very high credit ratings of AAA credit from Standard & Poor’s, AAA from Fitch, along with an Aa2 rating from Moody’s. Because of these excellent credit ratings, OCWD is able to borrow money at a substantially reduced cost. 7.2.3 WATER PURCHASES The District Act authorizes OCWD to purchase supplemental water for groundwater recharge to reduce overdraft of the basin. As described in Section 4, replenishment water is primarily purchased from Metropolitan, either as direct or in-lieu replenishment. This fund provides the flexibility to take advantage of surplus Metropolitan replenishment water or other surplus supplies when such supplies are available. During times of drought when replenishment water is unavailable for purchase, OCWD may budget funds for placement in reserve for future years. The District anticipates that surplus imported water will not be available for the next few years. A significant portion of the $19.1 million in the FY 2008-09 budget to purchase replenishment water will be placed in reserve. Funds in this account are also used to purchase treated full service supplies from MWDOC to blend with GWR System purified water for injection into the seawater barrier. 7.2.4 NEW CAPITAL EQUIPMENT This category includes equipment items such as laboratory equipment, vehicles, fax machines, tools, computers, and software. These items are expensed and funded using current revenues. 7.2.5 REFURBISHMENT AND REPLACEMENT FUND OCWD has over $700 million in existing plant and fixed assets. These facilities were constructed to provide a safe and reliable water supply. The Replacement and Refurbishment Fund was established to ensure that sufficient funds are available to repair and replace existing District infrastructure, such as pumps, heavy equipment, wells and water recycling facilities. 7-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 7 FINANCIAL MANAGEMENT 7.3 Operating Revenues Expected operating revenues for FY 2008-09 are shown in Table 7-2 and described below. Table 7-2 FY 2008-09 Operating Revenues REVENUES AMOUNT (in millions) Replenishment Assessments $84.5 Basin Equity Assessment 1.0 Property Taxes 18.1 Other Miscellaneous Revenue 12.7 Total $116.3 7.3.1 REPLENISHMENT ASSESSMENTS RAs are paid for all water pumped out of the basin. The District invoices Producers for their production in July and January. The amount of revenue generated by the RA is directly related to the amount of groundwater production. The RA is anticipated to generate $84.5 million in FY 2008-09 based on 341,058 af of total anticipated basin production. The BEA is assessed annually for all groundwater production above the BPP. The BEA rate is calculated for each agency and is currently approximately $381/af. Anticipated BEA revenues are budgeted at $1.0 million for FY 2008-09. 7.3.2 PROPERTY TAXES The District receives a small percentage of the property taxes, also referred to as ad valorem taxes, collected in the service area. For 2008-09, the District expects to receive approximately $18.1 million from property taxes. The County of Orange assesses and collects the property taxes and transmits them to the District at various times during the year. This revenue source has been dedicated to the District’s annual debt service expense. 7.3.3 OTHER MISCELLANEOUS REVENUE Cash reserves generate interest revenues. The majority of cash reserves are invested in short-term securities. Yields on cash reserves are anticipated to be low and have been estimated at three percent for 2008-09, for anticipated revenue of $4.2 million. Miscellaneous revenues are primarily comprised of water sales from the Green Acres Project and loan repayments. The loan repayments originate from the Conjunctive Use Well Program in which the District loaned Producers money at low interest rates for construction of new production wells and related facilities. In addition, numerous small items such as rents, subsidies, and minor fees are grouped in this account. Approximately $8.7 million is expected to be received in 2008-09. GROUNDWATER MANAGEMENT PLAN UPDATE 2009 7-3 ---PAGE BREAK--- SECTION 7 FINANCIAL MANAGEMENT 7.4 Reserves The District maintains cash reserves to ensure its financial integrity so that the basin can be successfully managed and protected. Cash reserves ensure that: • OCWD has sufficient funds for cash flow purposes; • Funds are available for unexpected events such as contamination issues; • Funds are available to make necessary replacements and repairs to infrastructure; • OCWD has access to debt programs with low interest cost; • A financial hedge is available to manage variable rate debt; and • Funds are available to purchase Metropolitan replenishment water when available. 7.4.1 RESERVE POLICIES The District has reserve policies, which establish reserves in the following categories: • Operating reserves • The Replacement and Refurbishment Program • The Toxic Cleanup Reserve • Contingencies required by the District Act • Bond reserve covenants 7.4.1.1 Operating Reserves This reserve category helps the District maintain sufficient funds for cash flow purposes and helps sustain the District’s excellent credit rating. Maintaining this reserve, which is set at 15 percent of the operating budget, is particularly important because the principal source of revenue, the RA, is only collected twice a year. Payments for significant activities, such as replenishment water purchases, are typically required on a basis. The reserve provides the financial “bridge” to meet the District’s financial obligations on a basis. 7.4.1.2 Replacement and Refurbishment Program The District maintains a Replacement and Refurbishment Fund to provide the financial resources for replacement and/or repair of the District capital assets. These assets include treatment facilities, monitoring and injection wells, and treatment facilities. The fund balance at the end of FY 2008-09 was projected to be approximately $41.2 million. 7.4.1.3 Toxic Cleanup Reserve Funds are reserved in this account to be used in the event that a portion of the basin becomes threatened by contamination. Over two million residents in the District rely on the basin as their primary source of water. Approximately $7 million is projected to be available in this reserve fund at the end of FY 2008-09 to allow the District to respond immediately to contamination threats in the basin. 7-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 7 FINANCIAL MANAGEMENT GROUNDWATER MANAGEMENT PLAN UPDATE 2009 7-5 7.4.1.4 General Contingencies Section 17.1 of the District Act requires the allocation of funds to cover annual expenditures that have not been provided for or that have been insufficiently provided for and for unappropriated requirements. This reserve amount is $3 million. 7.4.2 DEBT SERVICE ACCOUNT Restricted funds in this account have been set aside by the bonding institutions as a requirement to ensure financial solvency and to help guarantee repayment of any debt issuances. These funds cannot be used for any other purpose. The requirement varies from year to year depending on the District’s debt issuance and outstanding state loans. The account currently has approximately $5.5 million. 7.5 Capital Improvement Projects The District prepares a Capital Improvements Project budget to support basin production by increasing recharge capacity and operational flexibility, protect the coastal portion of the basin, and provide water quality improvements. The FY 2008-09 budget includes $20.5 million for this account. ---PAGE BREAK--- SECTION 7 FINANCIAL MANAGEMENT This page left blank intentionally 7-6 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- SECTION 8 RECOMMENDATIONS 8 RECOMMENDATIONS This section provides recommendations for the District to consider as part of ongoing management of the basin. The District’s programs to protect and increase the basin’s sustainable yield in a cost- effective manner continue to evolve due to increasing water demands and changes in the availability of recharge water supplies. The occurrence of wet and dry periods, the future availability and cost of imported water for groundwater recharge, and changing water management practices of agencies in the watershed will continue to affect the District’s management of the basin. The District’s programs to protect and enhance water quality will also continue to change due to new regulations and requirements. Recommendations for the District to continue its proactive management of the basin are summarized in Table 8-1. The table organizes these recommendations by general program area and also links the recommendations to the three management objectives of protecting and enhancing water quality, protecting and increasing the basin’s sustainable yield, and increasing the efficiency of OCWD’s operations. Specific projects that may be developed as a result of these recommendations would be reviewed and approved by the District’s Board of Directors and processed for environmental review prior to project implementation. TABLE 8-1 RECOMMENDATIONS PROGRAM/ACTIVITY PROTECT AND ENHANCE WATER QUALITY PROTECT AND INCREASE SUSTAINABLE YIELD INCREASE EFFICIENCY REPORTING AND MONITORING Continue to monitor groundwater elevations and the amount of water in storage to provide information to manage pumping in the basin within safe and sustainable levels 9 9 Continue to monitor groundwater quality and the quality of recharge water sources 9 Update the Groundwater Management Plan periodically 9 9 9 Update the Long Term Facilities Plan periodically 9 9 9 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 8-1 ---PAGE BREAK--- SECTION 8 RECOMMENDATIONS 8-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE PROGRAM/ACTIVITY PROTECT AND ENHANCE WATER QUALITY PROTECT AND INCREASE SUSTAINABLE YIELD INCREASE EFFICIENCY Continue annual publication of the Santa Ana River Water Quality Report; the Engineer’s Report on the Groundwater Conditions, Water Supply and Basin Utilization; the Santa Ana River Watermaster Report; and the Groundwater Replenishment System Operations Annual Report 9 9 9 Begin in 2009 periodic publication of the Report on Managed Aquifer Recharge in the Orange County Groundwater Basin 9 RECHARGE WATER SUPPLY MANAGEMENT Increase storage of storm flows behind Prado Dam through cooperative efforts with the ACOE 9 9 Monitor water management and recycling plans in the watershed for their potential impact upon OCWD recharge operations 9 9 Complete a feasibility study on reducing sediment loads in recharge water 9 9 Complete construction of the Initial Expansion of the GWR System 9 9 Increase drought preparedness through utilization of the full capacity of the GWR System 9 Develop improved tools to evaluate the efficiency of potential new recharge basins and proposed changes to existing recharge operations 9 9 Evaluate new approaches to groundwater recharge and approaches to increasing the efficiency of the District’s recharge facilities 9 9 Maintain and expand efforts to remove non-native vegetation and plant native vegetation in the watershed. 9 9 Promote incidental recharge to the extent feasible without negatively impacting groundwater quality 9 ---PAGE BREAK--- SECTION 8 RECOMMENDATIONS GROUNDWATER MANAGEMENT PLAN 2009 UPDATE 8-3 PROGRAM/ACTIVITY PROTECT AND ENHANCE WATER QUALITY PROTECT AND INCREASE SUSTAINABLE YIELD INCREASE EFFICIENCY WATER QUALITY MANAGEMENT Manage recharge water supplies so that water recharged through District facilities meets or is better than Department of Public Health MCLs and Notification Levels 9 Continue operation of Prado Wetlands in order to reduce nitrogen loads in Santa Ana River water 9 Complete and publish, in cooperation with Metropolitan and the NWRI, a research study on emerging constituents. 9 Prevent future contamination through coordinated efforts with regulatory agencies and watershed stakeholders 9 Complete construction and begin operation of the North Basin Groundwater Protection Project 9 Complete remedial investigation and begin construction of the South Basin Groundwater Protection Project 9 Address MTBE contamination 9 Open and begin operations of a new water quality laboratory in Fountain Valley 9 Maintain control of seawater intrusion in the Talbert Gap 9 9 Improve the performance of the Alamitos Seawater Barrier through evaluating need for additional injection wells and to construct necessary facilities 9 9 INTEGRATED MANAGEMENT OF PRODUCTION AND RECHARGE Continue to participate in cooperative efforts with watershed stakeholders 9 9 Operate the basin within a safe and sustainable operating range 9 ---PAGE BREAK--- SECTION 8 RECOMMENDATIONS 8-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE PROGRAM/ACTIVITY PROTECT AND ENHANCE WATER QUALITY PROTECT AND INCREASE SUSTAINABLE YIELD INCREASE EFFICIENCY FINANCIAL MANAGEMENT Set the Basin Production Percentage to optimize sustainable use of the groundwater 9 Manage finances to maintain high credit ratings 9 Maintain reserves for purchase of supplemental water supplies when available 9 ---PAGE BREAK--- SECTION 9 REFERENCES GROUNDWATER MANAGEMENT PLAN UPDATE 2009 9-1 9 References Alley, William 1984, Another Water Budget Myth: The Significance of Recoverable Ground Water in Storage, Ground Water, National Ground Water Association, 2006. Banks, Harvey Consulting Engineer, Groundwater Management, Irvine Area, Orange County, California, prepared for the Orange County Water District. Bawden, Gerald Wayne Thatcher, Ross S. Stein, Ken W. Hudnut, and Gilles Peltzer Tectonic Contraction Across Los Angeles After Removal of Groundwater Pumping Effects, Nature, Vol. 412, pp. 812-815, 2001. Blomquist, William, 1992, Dividing the Waters: Governing Groundwater in Southern California, Center for Self-Governance, San Francisco. Boyle Engineering Corporation, September 1994 and June 1996, Lindsay Avenue Well Treatment Study and Amendment – Laguna Beach County Water District. Membrane Softening Design Consideration for Meeting Changing Standards,. May 1995 Cape Hatteras, March 1997, Pilot Plant Study – Shallow Groundwater, Dare County, North Carolina. Boyle Engineering Corporation and Orange County Water District, 1997, Coastal Groundwater Management Investigation. California Department of Public Works, Division of Water Resources, 1934, South Coastal Basin Investigation, Geology and Ground Water Storage Capacity of Valley Fill, Bulletin No. 45. California Department of Water Resources, 1961, Ground Water Basin Protection Project: Santa Ana Gap Salinity Barrier, Orange County, Bulletin No. 147-1. 1967, Progress Report on the Ground Water Geology of the Coastal Plain of Orange County. 1968, Sea-Water Intrusion: Bolsa-Sunset Area, Orange County, Bulletin No. 63-2, pp. 186. California Department of Water Resources, 1989, Southern District, Analysis of Aquifer- System Compaction in the Orange County Ground Water Basin, prepared for Orange County Water District. Camp Dresser & McKee Inc., 2000, Groundwater Replenishment System, Project Development Phase – Development Information Memorandum No. 9A, Barrier System Modeling/Design Criteria, 100% Submittal, prepared for Orange County Water District and Orange County Sanitation District. 2003, Talbert Gap Model Refinement Report, prepared for Orange County Water District. ---PAGE BREAK--- SECTION 9 REFERENCES 9-2 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE CH2MHill, 2006, Chino Creek Integrated Plan: Guidance for Working Together to Protect, Improve, and Enhance the Lower Chino Creek Watershed, prepared for Inland Empire Utilities Agency. Clark, J. Hudson G.B, Davisson, M.L., Woodside, and Roy Herndon, 2004, Geochemical Imaging of Flow Near an Artificial Recharge Facility, Orange County, California. Ground Water. Vol 42, 2, 167-174. Dasgupta. P.K., et al. 2005. The origin of naturally occurring perchlorate: The role of atmospheric processes. Environmental Science and Technology, 39, 1569- 1575. Foubister, Vida. 2006. Analytical Chemistry, December 1, 2006, pages 7914-7915. Happel, A. Beckenback, E. and Halden, R. 1998, An evaluation of MTBE impacts to California groundwater resources (UCRL-AR-130897), Livermore, CA, Lawrence Livermore National Laboratory. Hardt, William F. and E. H. Cordes, 1971, Analysis of Ground-Water System in Orange County, California by Use of an Electrical Analog Model, USGS Open-File Report. Harley, et al, 1999, Model Advisory Panel Report. Prepared for OCWD. 2001, Model Advisory Panel Report. Prepared for OCWD. Interstate Technology & Regulatory Council. 2005. Perchlorate: Overview of Issues, Status, and Remedial Options. Perchlorate-1. Washington D.C.: Interstate Technology & Regulatory Council Perchlorate Team. Available on the internet at http://www.itrcweb.org Irvine Ranch Water District, May 1994, Organic Removal Testing Pilot Program. Kolpin, et al, 2002, Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams, 1999-2000: A National Reconnaissance, Environmental Science and Technology, 36, 1202-1211. McDonald and Harbaugh, 1988, Techniques of Water-Resources Investigations of the United States Geological Survey, Book 6, A Modular Three-Dimensional Finite- Difference Ground-Water Flow Model. McGillicuddy, Kevin 1989, Ground Water Underflow Beneath Los Angeles-Orange County Line, unpubl. M.S. thesis, Univ. of Southern California Dept. of Geological Sciences. Mesa Consolidated Water District and Orange County Water District, July 1997, Operating Data – Mesa Well No. 6 Pilot Plant – Mesa Consolidated Water District and Reed Corporation, January 1994, Process Design Report – Colored Water Treatment Plant – Well No. 6. Metropolitan Water District of Southern California and U.S. Department of Interior, Bureau of Reclamation, Salinity Management Study, 1999. ---PAGE BREAK--- SECTION 9 REFERENCES GROUNDWATER MANAGEMENT PLAN UPDATE 2009 9-3 Mills, William R. and Associates, Hydrogeology of the Yorba Linda Subarea and Impacts from Proposed Class III Landfills, prepared for the Orange County Water District, 1987. Montgomery, James Consulting Engineers, Inc., 1974, Bolsa Chica Mesa Water Quality Study, prepared for Orange County Water District. 1977, La Habra Basin Ground Water Study, prepared for City of La Habra, California. National Research Council. Health Implications of Perchlorate Ingestion. 2005. National Water Research Institute, 2000, Treatment Technologies for Removal of MTBE from Drinking Water: Air Stripping, Advanced Oxidation Processes, Granular Activated Carbon, Resin Sorbents, Second Edition. 2004, Report of the Scientific Advisory Panel, OCWD’s Santa Ana River Water Quality and Health Study. Nevada Division of Environmental Protection. 2009. http://ndep.nv.gov/BCA/perchlorate05.htm. Accessed on July 7, 2009. Orange County Water District, 1994, Hydrogeology and Groundwater Production Potential in the Vicinity of Brea Creek at Bastanchury Road, Fullerton, California. September 1996, Evaluation of the Orange County Colored Water Groundwater Resource: Hydrology, Water Quality and Treatment. June 1997, Issues Paper – Development of the Colored Water Zone. 1999, 2020 Master Plan Report for the Orange County Water District. 1970 to 2008, Engineer’s Report on Groundwater Conditions, Water Supply and Basin Utilization. 2003, Orange County Water District Recharge Study. December 2003. 2006, OCWD Application to Appropriate Santa Ana River Water. March 2006 2007, Report on Evaluation of Orange County Groundwater Basin Storage and Operational Strategy. February 2007 2009, Orange County Water District Long-Term Facilities Plan. Philip H.S. Kim, James M. Symons, December 1991, Using Anion Exchange Resins to Remove THM Precursors, AWWA Journal Poland, J. F. et al., 1956, Ground Water Geology of the Coastal Zone Long Beach- Santa Ana Area, California, USGS Water Supply Paper 1109. Ramsey, Robert 1980, Hydrogeology of La Habra Ground Water Basin, California, unpubl. M.S. thesis, Univ. of Southern California Dept. of Geological Sciences. Rong, Yue, 2002, Groundwater Data Analysis for MTBE Relative to Other Oxygenates at Gasoline-Impacted Sites, Environmental Geosciences 9 184-190. ---PAGE BREAK--- SECTION 9 REFERENCES 9-4 GROUNDWATER MANAGEMENT PLAN 2009 UPDATE Santa Ana River Watermaster, 2003, Thirty-Second Annual Report, Orange County Water District vs. City of Chino et al, Case No. 117628 – County of Orange. Santa Ana Watershed Project Authority, 2002, Integrated Watershed Plan. Spangenberg, Carl, et al, February 1997, Selection, Evaluation and Optimization of Organic Selective Membranes for Color and DBP Precursor Removal, AWWA Membrane Technology Conference. Singer, John 1973, Geohydrology and Artificial-Recharge Potential of the Irvine Area, Orange County, California, USGS Open-File Report 73-264. Tan, Lo and R. G. Sudak, January 1992, Removing Color From a Groundwater Source, AWWA Journal. Urbansky, E.T., et al. 2001. Environmental Pollution: 112, pages 299-302. U.S. Army Corps of Engineers, September 1994, Water Control Manual for the Prado Dam and Reservoir, Santa Ana River. U.S. Geological Survey, 1999, Land Subsidence in the United States, Circular 1182. Wildermuth Environmental, August 2008, Recomputation of Ambient Water Quality in the Santa Ana Watershed for the Period 1987-2006, Final Technical Memorandum. Prepared for the Basin Monitoring Task Force. ---PAGE BREAK--- APPENDICES APPENDIX A DOCUMENTS REGARDING PUBLIC PARTICIPATION APPENDIX B REQUIRED AND RECOMMENDED COMPONENTS FOR GROUNDWATER MANAGEMENT PLANS APPENDIX C GOALS AND MANAGEMENT OBJECTIVES DESCRIPTION AND LOCATION APPENDIX D REPORT ON EVALUATION OF ORANGE COUNTY GROUNDWATER BASIN STORAGE AND OPERATIONAL STRATEGY, OCWD, FEBRUARY 2007 APPENDIX E OCWD MONITORING WELLS APPENDIX F ACRONYMS AND ABBREVIATIONS ---PAGE BREAK--- APPENDIX A DOCUMENTS REGARDING PUBLIC PARTICIPATION ---PAGE BREAK--- APPENDIX A TABLE OF CONTENTS GROUNDWATER PRODUCERS MINUTES, JANUARY 14, 2009 WATER ISSUES COMMITTEE AGENDA, MAY 13, 2009 GROUNDWATER PRODUCERS MINUTES, MAY 13, 2009 OCWD WEBSITE NOTICE, MAY 13, 2009 OC REGISTER NOTICE, MAY 19, 2009 WATER ISSUES COMMITTEE AGENDA, JUNE 10, 2009 GROUNDWATER PRODUCERS MINUTES, JUNE 10, 2009 OCWD BOARD AGENDA, JUNE 17, 2009 COMMENTS FROM CITY OF ANAHEIM, JUNE 26, 2009 RESPONSES TO COMMENTS NOTICE OF EXEMPTION CERTIFICATION OF BOARD ACTION APPROVING GROUNDWATER MANAGEMENT PLAN 2009 UPDATE ---PAGE BREAK--- MINUTES GROUNDWATER PRODUCERS MEETING Sponsored by the ORANGE COUNTY WATER DISTRICT Field Headquarters, Anaheim Wednesday, January 14, 2009, 10 AM 1. MTBE Sampling Update Roy Herndon informed the group that the latest round of sampling and low level testing had been completed with the lab hired by the District. And that low levels of MTBE had been detected in about 1/3 of the major production wells in the basin. The Producers were told to contact Roy if they wanted specific information on their individual wells. 2. Long-Term Facilities Plan Report The Producers were asked to get any comment letters they may have on the final draft report to OCWD by January 21, 2009. OCWD will then respond to those letters. The LTFP final review will occur at the next Producers meeting on February 11, 2009 and could then go to the OCWD Board on February 18, 2009. The recent Golden State Water Company letter on the LTFP was distributed. 3. Groundwater Management Plan – 5 Year Update Greg Woodside informed everyone of the need to update the GWMP to comply with state guidelines. The District is working to provide a draft of the updated document in late February and to take it to the OCWD Board in April. Greg reviewed potential basin management goals for the document. 4. Santiago Pump Station Project The same presentation on this project provided to the Water Issues Committee was given to the Producers. It was suggested that OCWD should show the financial savings and the additional recharge created by the project. 5. FY09-10 Budget process update John Kennedy provided an update on several budget related issues including: • OCWD is working to provide FY09-10 RA and BPP projections by January 21. • The District will also provide the draft FY09-10 Work Plans for each of the cost centers on January 21. OCWD Staff was also asked to provide a BEA estimate and an estimate of what the Accumulated Overdraft would be at the end of FY09-10 1 ---PAGE BREAK--- 2 6. Follow-up on Producer letter regarding modeling for the Talbert Barrier and Basin Storage OCWD’s response letter to the Producers regarding this issue was provided. Bob McVicker provided comments on the need to better understand color water upwelling in their part of the groundwater basin. 7. Other ---PAGE BREAK--- AGENDA ITEM SUBMITTAL Meeting Date: May 13, 2009 Budgeted: N/A Budgeted Amount: N/A To: Water Issues Committee Cost Estimate: N/A Board of Directors Funding Source: N/A Program/Line Item No.: N/A From: Mike Markus General Counsel Approval: N/A Engineers/Feasibility Report: N/A Staff Contact: G. Woodside/C. Miller CEQA Compliance: Exemption to be filed upon Board receipt of final plan Subject: REVIEW OF UPDATED GROUNDWATER MANAGEMENT PLAN SUMMARY Staff has prepared a draft updated Groundwater Management Plan (Plan). The Plan was last updated in 2004. Staff will distribute the draft updated Plan for review by the Board and Producers. The Plan will also be posted on the District’s web site. RECOMMENDATION Informational BACKGROUND/ANALYSIS The District prepared its first Groundwater Management Plan in 1989. The Plan was last updated in 2004. The Plan needs to be updated to remain consistent with guidelines established by the California Department of Water Resources. The California Water Code sets forth the process for adopting and updating a Groundwater Management Plan. The Water Code lists components that must be included and requires the completion of plans in order for the state to grant public funds for construction of certain groundwater projects. The 2009 Draft Update proposes the District’s overall goals in managing the basin as follows: • To protect and enhance groundwater quality, • To protect and increase the sustainable yield of the basin in a cost-effective manner, and • To increase the efficiency of OCWD’s operations. ---PAGE BREAK--- The updated Plan will be made available for public review. Staff will respond to comments from the Board, Producers, and the public and will prepare a revised version that addresses the comments received. Staff will then recommend that the Plan be adopted by the Board. The proposed schedule is: May 13, 2009 Post Draft Updated Plan on OCWD website May 14, 2009 Post public notice in Orange County Register June 10, 2009 Workshop at Water Issues Committee and Producers Meeting June 17, 2009 Public Hearing at OCWD Board meeting June 24, 2009 Deadline for public comment July 15, 2009 Consideration of adoption by Board of Directors According to the Department of Water Resources, plan updates should provide a historical record of progress, including projects completed and how those projects improved resource management. The 2009 Update explains how OCWD manages the groundwater basin in order to accomplish the stated management objectives. Major accomplishments since the adoption of the 2004 plan are listed and completed projects are described, examples of which are listed below: • Analysis of 14,000 water quality samples in 2008. • Completion of the Groundwater Replenishment System in 2008. • Development of the three-layer method of determining maximum accumulated overdraft and publication of the Report on Evaluation of Orange County Groundwater Basin Storage and Operational Strategy in 2007. • Improvements to recharge operations such as completion of the La Jolla Recharge Basin, the Kraemer-Miller pipeline improvements, and the Santiago Creek Recharge Enhancement Project. • Completion of water quality improvement projects such as the Irvine Desalter and the initiation of the North and South Basin Groundwater Protection Projects. PRIOR RELEVANT BOARD ACTION(S) None ---PAGE BREAK--- Minutes GROUNDWATER PRODUCERS MEETING Sponsored by the ORANGE COUNTY WATER DISTRICT 18700 Ward Street, Fountain Valley (714) 378-3200 Wednesday, May 13, 2009, 10 AM 1. Groundwater Management Plan Update Greg Woodside gave an overview of the updated GWMP and how it would be processed this summer. A draft report was distributed. Greg reviewed the report recommendations. 2. Review FY09-10 BPP/BEA/Pumping Limitation and Surcharge John Kennedy reviewed the new rates and charges for FY09-10 3. Annexation Update John Kennedy provided a summary of how the District plans to terminate the 2004 annexation MOU with IRWD and the City of Anaheim. After responses are provided on the draft January 2006 Program EIR the District will formally inform IRWD and Anaheim of the termination as allowed for in Section 7 of the MOU. Future annexations could still be considered but under a different process from what was provided for in the 2004 MOU. Other comments included that Producers interested in annexing may be required to submit new applications. Additionally if annexations are considered individually, there is still a need to review the cumulative potential annexations. ---PAGE BREAK--- With the MOU terminated the District can receive and file the Long-Term Facilities Plan Report. The LTFP will be reviewed with the Producers in June and taken to the OCWD Board in July. 4. GWR System Update a. Expansion Mike Markus gave an update on the process to select a design consultant for the expansion and some of the issues that need to be resolved. It was mentioned that OCWD should reassess the projects viability at key milestones prior to 100% design. b. Existing plant water supply unit cost for FY08-09 A handout was provided which shows the existing unit cost at $582/af after the first nine months of FY08-09 5. Other Bob McVicker asked that OCWD provide BPP projections for future years. Discussion on AB1100 also incurred regarding legislation that would allow OCWD to bottle a small amount of GWR System water. Information: OCWD May 20, 2009 Board meeting moved to May 27th. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- AGENDA ITEM SUBMITTAL Meeting Date: June 10, 2009 Budgeted: N/A Budgeted Amount: N/A To: Water Issues Committee Cost Estimate: N/A Board of Directors Funding Source: N/A Program/Line Item No.: N/A From: Mike Markus General Counsel Approval: N/A Engineers/Feasibility Report: N/A Staff Contact: G. Woodside/C. Miller CEQA Compliance: Exemption to be filed upon Board adoption of updated plan Subject: UPDATE: 2009 GROUNDWATER MANAGEMENT PLAN, PUBLIC COMMENT PERIOD AND PUBLIC HEARING SUMMARY Staff distributed draft copies of the updated Groundwater Management Plan (Plan) to the Board and Producers on May 13, 2009. Public notices were published in the Orange County Register and the draft plan was posted on the District’s web site. A public hearing on the draft Plan will be held at the June 17 Board of Directors Meeting. RECOMMENDATION Informational BACKGROUND/ANALYSIS The District prepared its first Groundwater Management Plan in 1989. The Plan has been updated periodically to incorporate new information, and was last updated in 2004. The Plan needs to be periodically updated to remain consistent with guidelines established by the California Department of Water Resources. The California Water Code lists components that must be included and requires the completion of plans in order for the state to grant public funds for construction of certain groundwater projects. The 2009 Plan discusses the District’s overall goals in managing the basin as follows: • To protect and enhance groundwater quality, • To protect and increase the sustainable yield of the basin in a cost-effective manner, and • To increase the efficiency of OCWD’s operations. ---PAGE BREAK--- The comment period for the Plan is now open. Staff will respond to comments from the Board, Producers, and the public and will prepare a revised version that addresses comments received. The proposed schedule for adopting the plan is as follows: June 10, 2009 Workshop at Water Issues Committee and Producers Meeting June 17, 2009 Public Hearing at OCWD Board meeting June 24, 2009 Deadline for public comment July 15, 2009 Consideration of Plan adoption by Board of Directors According to the Department of Water Resources, plan updates should provide a historical record of progress, including projects completed and how those projects improved resource management. The 2009 Update explains how OCWD manages the groundwater basin in order to accomplish the stated management objectives. Major accomplishments since the adoption of the 2004 Plan are listed and completed projects are described, examples of which are listed below: • Analysis of 14,000 water quality samples in 2008. • Completion of the Groundwater Replenishment System in 2008. • Development of the three-layer method of determining maximum accumulated overdraft and publication of the Report on Evaluation of Orange County Groundwater Basin Storage and Operational Strategy in 2007. • Improvements to recharge operations such as completion of the La Jolla Recharge Basin, the Kraemer-Miller pipeline improvements, and the Santiago Creek Recharge Enhancement Project. • Completion of water quality improvement projects such as the Irvine Desalter and the initiation of the North and South Basin Groundwater Protection Projects. PRIOR RELEVANT BOARD ACTION(S) None ---PAGE BREAK--- Minutes GROUNDWATER PRODUCERS MEETING Sponsored by the ORANGE COUNTY WATER DISTRICT 18700 Ward Street, Fountain Valley (714) 378-3200 Wednesday, June 10, 2009, 10 AM 1. Water Quality Issues None 2. Review Groundwater Management Plan Greg Woodside updated everyone on the processing of the GWMP. The Producers were provided a copy of the GWMP last month. 3. Review Long-Term Facilities Plan Greg Woodside reviewed the LTFP and the schedule for completing the document. The document will be mailed and emailed to everyone this week. 4. Update on Warner Basin Hopkins Development Study Mike Markus updated the group on the preliminary development work occurring with the Hopkins group and the District’s likely plans to continuing exploring this idea for the next six months. Hopkins is looking at ideas to place retail development around Warner Basin but would need to compensate OCWD for any lost percolation. 5. FY10-11 BPP Projections John Kennedy distributed some preliminary FY10-11 BPP projections for planning purposes. OCWD was asked to provide an RA projection also at next months meeting. 6. Potential loss of Ad Valorem property tax – Prop 1A The District is closely monitoring the Sacramento budget discussions and the potential loss of a portion of our $19 million in property tax income. We are unsure if the state plans to take or borrow some of these revenues. Eleanor Torres informed everyone that the District may have ---PAGE BREAK--- discussions with some local City Councils on this issue and would coordinate such with the Producers. 7. OCWD Long-Term Variable Rate Debt Program Mike Markus explained how the District’s variable rate debt cost has increased due to a downgrading of the German Landesbank (who provides the letter of credit for the deal). OCWD may convert the debt to fixed rate debt. 8. Garden Grove Well 28 & Laguna Beach potential program The Producers were informed that the District, Garden Grove and Laguna Beach have met to discuss a possible option to pump and treat the GG Well 28 which has high nitrates. The potential deal would incorporate an agreement the District has with LB to pump 2,025 afy of ground water. When additional details are developed they will be brought back to a future Producers meeting. 9. Select a Vice Chair for the Producers Group in FY09-10 Rick Shintaku of Anaheim was elected to be the Vice Chairman 10. Other Mike Markus updated everyone on the GWR System flows and the plans to hire a design consultant to expand the plant from 70 mgd to 100 mgd. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- From: Dick Wilson [mailto:[EMAIL REDACTED]] Sent: Friday, June 26, 2009 11:40 AM To: Woodside, Greg Cc: Rick Shintaku; Don Calkins Subject: Draft Groundwater Mgmt Plan Greg, here are my comments on the Draft GWMP: 1. I would like to see an objective such as, “Promote incidental recharge to the extent feasible without impacting groundwater quality.” This could be added to Section 1.8.2 and Section 8 and generally included throughout the document. 2. Section 4 should include a discussion of ways to increase incidental recharge. According to the document, incidental recharge accounts for about 20% of the total recharge, and this is with the vast majority of storm flows escaping over streets and into concrete storm drains. There’s a huge volume of water that could be captured for future use via “dry wells,” swales, wetlands, etc. If we are to sustain our groundwater basin, we will need to take advantage of this resource. 3. Section 5 should include a discussion of perchlorate contamination including where it came from, how its dispersing in the groundwater basin and how long before it is “gone.” 4. Several of the figures are too small of scale. For example, on Figure ES‐5, you cannot distinguish between monitoring wells and production wells. The figures should be larger, or less information provided on them. I concur that we should not disclose exact locations of production wells, but it’s very important to know exactly where the monitoring wells are located. 5. In several cases it may be better to provide data in tables rather than graphs. For example, Figure ES‐10 would be much easier to comprehend if the data were provided in a table. It is very difficult to assess trends for data in stacked bar graphs. 6. Overall, it’s an excellent document and will be a valuable resource. OCWD should recognize that all water producers in the Basin will need to include this document in State and Federal grant applications and the Plan should include a broad spectrum of concepts for improving groundwater sustainability. If you’d like to talk about any of these issues, please feel free to contact me. Dick Wilson Environmental Services Manager Anaheim Public Utilities Department [PHONE REDACTED] [EMAIL REDACTED] THIS MESSAGE IS INTENDED ONLY FOR THE USE OF THE INDIVIDUAL OR ENTITY TO WHICH IT IS ADDRESSED AND MAY CONTAIN INFORMATION THAT IS PRIVILEGED, CONFIDENTIAL, AND EXEMPT FROM DISCLOSURE UNDER APPLICABLE LAWS. If the reader of this message is not the intended recipient, or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution, forwarding, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by e-mail or telephone, and delete the original message immediately. Thank you. ---PAGE BREAK--- Response to Comments received June 26, 2009 from Dick Wilson, Environmental Services Manager, Anaheim Public Utilities Department No. Comment Response to Comment 1 Add objective related to promoting incidental recharge such as “Promote incidental recharge to the extent feasible without impacting groundwater quality.” A new objective promoting incidental recharge has been added to Section 1.8.2. This new objective was added to Section 8. 2 Discuss ways to increase incidental recharge. A discussion of incidental recharge was added in Section 4.2.2.1. 3 Add a discussion of perchlorate contamination to Section 5. A new section on perchlorate, Section 5.6, was added. 4 The scale of several figures is too small. In Figure ES-5, it is difficult to distinguish between monitoring and production wells. Several of the figures throughout the document were enlarged for improved readability. The clarity of Figure ES-5 was improved to enable the reader to distinguish between the production and monitoring wells. Please note that in Section 3, the production wells and monitoring wells appear in separate figures (Figures 3-1 and 3-2). 5 In some cases, data should be provided in tables rather than graphs. Figure ES-10 would be easier to comprehend if data were provided in a table. It is difficult to assess trends for data in stacked bar graphs. Figure ES-10 appears also as Figure 6-5 in Section 6. A table with the data used to create Figure 6-5 was added in Section 6.6. 6 Since water producers will need to include this document in state and federal grant applications, the plan should include a broad spectrum of concepts for improving groundwater sustainability. Comment noted. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- APPENDIX B REQUIRED AND RECOMMENDED COMPONENTS FOR GROUNDWATER MANAGEMENT PLANS ---PAGE BREAK--- Appendix B Mandatory and Recommended Components of a Groundwater Management Plan No. Mandatory Components of a GWMP Water Code Section OCWD Plan Section 1. Basin management objectives for the groundwater basin that is subject to the plan 10753.7(a)(1) 1.8, 5.1.1, 5.1.2, 5.2.3, 6.3 2. Monitoring and management of groundwater levels within the groundwater basin 10753.7(a)(1) 1.8.2, 2.2, 2.3, 2.4, 2.6, 2.7 3. Monitoring protocols that are designed to detect changes in groundwater levels 10753.7(a)(4) 2.3, 2.4, 2.8, 3.1, 3.2, 3.4, 4. Groundwater quality degradation 10753.7(a)(1) 1.8.1, 3.5, 5 5. Monitoring protocols that are designed to detect groundwater quality 10753.7(a)(4) 3.1, 3.2, 3.3, 3.5, 3.6, 5 6. Inelastic land surface subsidence 10753.7(a)(1) 2.7 7. Monitoring protocols that are designed to detect inelastic land surface subsidence for basins for which subsidence has been identified as a potential problem 10753.7(a)(4) 2.7 8. Changes in surface flow and surface water quality that directly affect groundwater levels or quality or are caused by groundwater pumping in the basin 10753.7(a)(1) 3.7, 4, 6.7 9. Monitoring protocols that are designed to detect flow and quality of surface water that directly affect groundwater levels or quality or are caused by groundwater pumping at the basin 10753.7(a)(4) 3.7, 4, .6.5, 6.7 10. A plan to involve other agencies that enables the local agency to work cooperatively with other public entities whose service area or boundary overlies the groundwater basin 10753.7(a)(2) 1.2, 6.2 11. A map that details the area of the groundwater basin, as defined in the department's Bulletin No. 118, and the area of the local agency, that will be subject to the plan, as well as the boundaries of other local agencies that overlie the basin in which the agency is developing a groundwater management plan 10753.7(a)(3) Figures 1-1, 1-5, 2-1 ---PAGE BREAK--- Appendix B Mandatory and Recommended Components of a Groundwater Management Plan Item Optional Components of a GWMP Water Code Section OCWD Plan Section 12. The control of saline water intrusion 10753.8(a) 3.6, 5.2 13. Identification and management of wellhead protection areas and recharge areas 10753.8(b) 4, 5.1.5, 6.2 14. Regulation of the migration of contaminated groundwater 10753.8(c) 5 15. The administration of a well abandonment and well destruction program 10753.8(d) 5.1.6, 5.1.7 16. Mitigation of conditions of overdraft 10753.8(e) 2.5, 6.5, 6.7, 6.8, 7.2.3 17. Replenishment of groundwater extracted by water producers 10753.8(f) 4, 6 18. Monitoring of groundwater levels and storage 10753.8(g) 1.8.2, 2.2, 2.3, 2.4, 2.6, 2.7, 2.8, 3.1, 3.2, 3.4, 6.5, 6.7, 6.8 19. Facilitating conjunctive use operations 10753.8(h) 3.7.4, 6.3.3, 6.7, 6.8 20. Identification of well construction policies 10753.8(i) Figures 3-4, 3-5, 5.1.5, 5.1.6 21. The construction and operation by the local agency of groundwater contamination cleanup, recharge, storage, conservation, water recycling and extraction projects 10753.8(j) 4, 5.2.5, 5.3.3, 5.8,5.9, 6 22. The development of relationships with state and federal regulatory agencies 10753.8(k) 5.1.3, 6.2 23. The review of land use plans and coordination with land use planning agencies to assess activities which create a reasonable risk of groundwater contamination 10753.8(l) 5.1.4, 5.1.5 ---PAGE BREAK--- APPENDIX C GOALS AND BASIN MANAGEMENT OBJECTIVES DESCRIPTION AND LOCATION ---PAGE BREAK--- Appendix C 1 Goals and Basin Management Objectives Description and Location Basin Management Objective (BMO) How Meeting BMO will Contribute to More Reliable Supply of Groundwater Location of Description of Planned Management Actions General Basin Management Objectives to Accomplish All Goals Update the Groundwater Management Plan periodically Sections 1.4, 3.8 Update the Long-Term Facilities Plan periodically Sections 1.4 and 4.5 Continue annual publication of the Santa Ana River Water Quality Report; the Engineer’s Report on the Groundwater Conditions, Water Supply and Basin Utilization; the Santa Ana River Watermaster Report; and the Groundwater Replenishment System Operations Annual Report. Regular publication of reports enables the District to plan for and manage the groundwater basin responsibly and efficiently, assure the timely construction of necessary projects to accomplish stated basin management objectives, and monitor the water quality of the basin and recharge water supplies. Sections 1.5, 2.8, 3.8, and 6.5 Goal: Protect and Enhance Groundwater Quality Conduct monitoring programs Section 3 Monitor and manage quality of recharge water supplies so that water recharged through District facilities meets or is better than primary drinking water levels and notification levels Section 4 and 5 Monitor quality of Santa Ana River water Comprehensive monitoring of ground and surface water quality enables OCWD to discover contamination at an early stage and begin remediation efforts at the earliest feasible time and assures that operations are in compliance with federal, state, and local laws and regulations. Section 3.7 ---PAGE BREAK--- Appendix C 2 Goals and Basin Management Objectives Description and Location Basin Management Objective (BMO) How Meeting BMO will Contribute to More Reliable Supply of Groundwater Location of Description of Planned Management Actions Implement the District’s Groundwater Protection Policy The Groundwater Protection Policy proactively protects the water quality of the basin and enables the District to work to clean up contaminated areas. Section 5 Construct and manage water quality treatment projects Water quality treatment projects clean up contamination in order to protect the long-term quality of groundwater in the basin. Section 5.8 Operate seawater intrusion barriers Barriers prevent intrusion of high salinity water into the basin. Section 3.6 Support natural resource programs in the watershed Improvement of natural resources in the watershed contributes to higher quality source water for OCWD recharge operations. Section 6.2.2 Participate in cooperative efforts with regulators and stakeholders within the Santa Ana River Watershed Working with stakeholders in the watershed helps to protect the quality of source water used to recharge the groundwater basin. Section 3.7, 5.2.5, and 6.2 ---PAGE BREAK--- Appendix C 3 Goals and Basin Management Objectives Description and Location Basin Management Objective (BMO) How Meeting BMO will Contribute to More Reliable Supply of Groundwater Location of Description of Planned Management Actions Goal: Protect and Increase the Basin’s Sustainable Yield in a Cost Effective Manner Monitor groundwater levels, recharge rates, and production rates Operate the basin in accordance with the Groundwater Basin Storage and Operational Strategy Proper monitoring and operation of the groundwater basin improves groundwater management by establishing safe and sustainable levels of groundwater production, determines that extent of seawater intrusion so improvements to seawater barriers can be made, and allows for management of the basin for maximum pumping of groundwater at levels that assure sustainable supplies over the long- term. Section 2 and 3 Manage recharge operations to maximize recharge of the groundwater basin Proper and efficient management of recharge operations sustains maximum pumping of groundwater supplies. Section 4 Research and implement new strategies and programs to increase recharge capacity New strategies and programs increase the amount of groundwater available for pumping from the basin. Section 4.3 and 4.4 Promote incidental recharge to the extent feasible without negatively impacting groundwater quality. Increasing incidental recharge increases the amount of water naturally percolating into the groundwater basin, which increases the amount of water available for pumping from the basin. Section 4.2.2.1 Plan and conduct programs that maximize the capacity of the basin to respond to and recover from droughts Increases the amount of water the basin can provide during a drought. Section 6.8 ---PAGE BREAK--- Appendix C 4 Goals and Basin Management Objectives Description and Location Basin Management Objective (BMO) How Meeting BMO will Contribute to More Reliable Supply of Groundwater Location of Description of Planned Management Actions Support natural resource programs in the watershed Natural resource programs, such as removal of Arundo, augment available supplies of recharge water. Sections 5.3.3 and 6.2.2 Goal: Increase Operational Efficiency Manage the District’s finances to provide long-term fiscal stability and to maintain financial resources to implement District programs Operate District programs in a cost-effective and efficient manner. Fiscal stability is essential for the District to effectively manage the groundwater basin. Maintenance of reserves allows for the purchase of supplemental water supplies when they are available. Section 7 Manage natural resource programs in the Santa Ana River watershed in an efficient manner. Removal of excessive nitrate levels through the operation of Prado Wetlands saves the cost of more expensive treatment plan construction and operation. Removal of Arundo increases water supply availability. Sections 5.3.3 and 6.2.2 Implement efficient environmental management programs, such as use of solar power where feasible. Replacing a portion of the District’s use of electricity with generation of solar power will reduce costs in the long run. Section 4.5 ---PAGE BREAK--- APPENDIX D REPORT ON EVALUATION OF ORANGE COUNTY GROUNDWATER BASIN STORAGE AND OPERATIONAL STRATEGY, OCWD, FEBRUARY 2007 ---PAGE BREAK--- ---PAGE BREAK--- TABLE OF CONTENTS EXECUTIVE 1 1. 4 2. STUDY OBJECTIVES AND WORK 8 3. STORAGE CHANGE CALCULATION METHODOLOGY 8 3.1 Aquifer Storage Concept 8 3.2 Confined and Unconfined 9 3.3 Traditional Storage Change Calculation Method 10 Water Level Change 10 Water Budget 11 Limitations of the Traditional Storage Change 11 3.4 New Three-Layer Storage Change 13 13 GIS Application for Three-Layer Storage Change Calculation 17 Testing the Three-Layer Method vs. the Traditional Method 18 4. NEW FULL BASIN BENCHMARK 21 4.1 Assumptions and Methodology 22 4.2 Shallow Aquifer Full Basin Water Level 23 4.3 Principal Aquifer Full Basin Water Level 29 4.4 Deep Aquifer Full Basin Water Level 32 5. ACCUMULATED OVERDRAFT FROM NEW FULL 34 5.1 Accumulated Overdraft as of June 30, 34 5.2 Accumulated Overdraft as of June 30, 35 5.3 Historical vs. New Overdraft Estimates 36 5.4 Implementation of New Three-Layer Storage Change 37 6. BASIN OPERATING RANGE AND STRATEGY 38 6.1 Basin Operating Range and Optimal 39 6.2 Basin Management Operational 41 7. 43 8. RECOMMENDATIONS 45 9. BIBLIOGRAPHY 45 ---PAGE BREAK--- 2 LIST OF TABLES Table 1-1. Pumping and Recharge Conditions: WY 1968-69 vs. WY 2004-05 Table 6-1. Anticipated Supply Increases for a Typical Wet Year Table 6-2. Anticipated Supply Reductions for Typical Dry Years LIST OF FIGURES Figure 1-1. Groundwater Pumping Distribution: WY 1968-69 and WY 2004-05 Figure 1-2. Schematic of Groundwater Level Profiles Across the Basin Figure 1-3. Water Level Hydrograph for City of Anaheim Well 27 Figure 3-1. Forebay and Pressure Area Schematic Profile Figure 3-2. Water Level Hydrograph for OCWD Monitoring Well SAR-2 Figure 3-3. Schematic Cross-Section of the Basin Showing Three Aquifer Layers Figure 3-4. Schematic cross-section showing storage coefficients values Figure 3-5. June 2006 Shallow Aquifer Groundwater Elevations and Proposed Wells Figure 3-6. November 2004-05 Water Level Change at Monitoring Well SAR-2 Figure 3-7. Summary of Traditional vs. Three-Layer Storage Change Results Figure 4-1. Principal Aquifer Water Level Change: November 1969 to June 2006 Figure 4-2. Full Basin Water Level at Anaheim Well 27 Figure 4-3. Shallow Aquifer Groundwater Contours: Full Basin and June 2006 Figure 4-4. Shallow Aquifer Depth to Water: Full Basin and June 2006 Figure 4-5. Full Basin Water Level at Santa Ana Well 21 Figure 4-6. Full Basin Water Level at Mesa Consolidated Water District Well 2 Figure 4-7. Principal Aquifer Groundwater Contours: Full Basin and June 2006 Figure 4-8. Deep Aquifer Groundwater Contours: Full Basin and June 2006 Figure 5-1. Three-Layer Accumulated Overdraft for June 2006 Figure 5-2. Average Shallow Aquifer Water Level Difference from June 2006 to Full Figure 5-3. Accumulated Overdraft Schematic for June 2005 and June 2006 Figure 5-4. Historical and New Accumulated Overdraft Figure 6-1. Strategic Basin Operating Levels and Optimal Target Figure 6-2. BPP Formula Figure 6-3. Basin Management Operational Strategy ---PAGE BREAK--- 3 APPENDICES APPENDIX 1: “Randall” Specific Yield Values from Traditional Storage Change Method APPENDIX 2: Basin Model Storage Coefficient Values for Three-Layer Storage Change Method APPENDIX 3: Water Level Change Maps for June 2006 to the New Full Condition APPENDIX 4: GIS Application for Three-Layer Storage Change Calculation Acknowledgment Much assistance was provided by District GIS staff Dan Lee and Linda Koki, specifically with implementation and automation of the new three-layer storage change algorithm, GIS programming, mapping, and graphical support. ---PAGE BREAK--- 1 EXECUTIVE SUMMARY The need for this study was largely driven by the record-setting wet year of 2004-05, in which an unprecedented storage increase of 170,000 af was estimated by OCWD staff. This led to a preliminary reassessment of the traditional storage calculation which, due to cumulative uncertainty over tens of years, could not be sufficiently rectified back to the traditional full-basin benchmark of 1969. A new methodology has been developed, tested, and documented herein for calculating accumulated overdraft and storage change based on a three aquifer layer approach, as opposed to the previous single-layer method. Also, for calculating accumulated overdraft, a new full-basin benchmark was developed for each of the three aquifer layers, thereby replacing the traditional single-layer full benchmark of 1969. Also in this report, a basin management operational strategy is proposed that sets guidelines for planned refill or storage decrease amounts based on the level of accumulated overdraft. The new three-layer storage change approach utilizes aquifer storage parameters supported by calibration of the District’s basin-wide groundwater model (“basin model”) along with actual measured water level data for each of the three aquifer systems that correspond to the three aquifer layers in the basin model: the Shallow, Principal, and Deep (colored water) aquifer systems. Traditionally, the storage change calculation was based solely on groundwater levels for the Principal aquifer, from which approximately 90 percent of basin pumping occurs. The findings of this study are enumerated below. 1. The new three-layer storage change approach is technically feasible and provides a more accurate assessment than the traditional single-layer storage change method. 2. Using the new three-layer method, the majority of the storage change occurs in the Forebay area of the basin within the unconfined Shallow aquifer where rising or falling of the water table fills or drains empty pore space. 3. Accuracy of the storage change and accumulated overdraft estimates is dependent upon good spatial distribution of water level measurements as well as the storage coefficient values used in the calculations. Water level data for the Shallow aquifer were relatively sparse in outlying Forebay areas of the basin, leading to some uncertainty in preparing groundwater elevation contours in those areas. 4. 1969 no longer represents a truly full-basin benchmark. A new full-basin water level condition was developed based on the following prescribed conditions: • Observed historical high water levels • Present-day pumping and recharge conditions • Protective of seawater intrusion • Minimal potential for mounding at or near recharge basins ---PAGE BREAK--- 2 The new full-basin water levels in the Forebay area are essentially at or very near the bottom of the District’s deep percolation basins Anaheim Lake). Historical water level data from 1994 have shown that this condition is achievable without detrimental effects. Water levels higher than this new full condition may be physically achievable in the Forebay area but not recommended due to the likelihood of groundwater mounding and reduced percolation in recharge basins. 5. Using the new three-layer storage change calculation in conjunction with the new full benchmark and June 2006 water levels, an accumulated overdraft of 135,000 af was calculated representing June 30, 2006. Similarly, using the new three-layer method to compare the new full water levels to those of June 2005, an accumulated overdraft of 201,000 af was calculated representing June 30, 2005. Subtracting the June 2006 accumulated overdraft from that of June 2005 yielded an annual storage increase of 66,000 af for WY 2005-06. 6. Comparing the current year’s water level conditions to the full basin benchmark each successive year for calculating the basin storage will eliminate the potential for cumulative discrepancies over several years. 7. An accumulated overdraft of 500,000 af represents the lowest acceptable limit of the basin’s operating range. This lower limit of 500,000 af assumes that stored MWD water (CUP and Super In-Lieu) has already been removed and is only acceptable for short durations due to drought conditions. It is not recommended to manage the basin for sustained periods at this lower limit for the following reasons: • Seawater intrusion likely • Drought supply depleted • Pumping levels detrimental to a handful of wells • Increased pumping lifts and electrical costs • Increased potential for color upwelling from the Deep aquifer 8. An optimal basin management target of 100,000 af of accumulated overdraft provides sufficient storage space to accommodate increased supplies from one wet year while also providing enough water in storage to offset decreased supplies during a two- to three-year drought. 9. The proposed operational strategy provides a flexible guideline to assist in determining the amount of basin refill or storage decrease for the coming water year based on using the BPP formula and considering storage goals based on current basin conditions and other factors such as water availability. This strategy is not intended to dictate a specific basin refill or storage decrease amount for a given storage condition but to provide a general guideline for the District’s Board of Directors. ---PAGE BREAK--- 3 Based on the above findings, recommendations stemming from this study are as follows: 1. Adopt the new three-layer storage change methodology along with the associated new full-basin condition that will serve as a benchmark for calculating the basin accumulated overdraft. 2. Adopt the proposed basin operating strategy including a basin operating range spanning the new full condition to an accumulated overdraft of 500,000 af, and an optimal overdraft target of 100,000 af. 3. Include in the 2007-08 CIP budget the installation of six Shallow aquifer monitoring wells to increase accuracy of the three-layer storage change calculation. ---PAGE BREAK--- 4 1. INTRODUCTION This report documents the methodology, findings, and recommendations of the basin storage and overdraft evaluation completed by District staff between May 2006 and January 2007. Prior to this study, an unusually large annual increase in basin storage of 170,000 af was estimated for WY 2004-05, which was a record-setting wet year. During that year, water levels throughout the basin rose approximately 30 feet overall, and as much as 60 feet in the Santiago recharge area which receives significant storm runoff from Villa Park Dam releases during extremely wet years. The estimated storage increase for WY 2004-05 was so large that it caused staff to re- examine the storage calculation. Also, the large water level rise during that year raised concern that the basin could be approaching a near-full condition, leading staff to compare 2005 water levels throughout the basin to 1969 in which the basin was historically considered full. This analysis showed that the basin may have had only 40,000 af less groundwater in storage in November 2005 as compared to the 1969 benchmark. However, the traditional method of cumulatively adding the annual storage change each year to the previous year’s accumulated overdraft led to an accumulated overdraft of approximately 190,000 af for November 2005. The discrepancy of 150,000 af in the two different 2005 overdraft calculations indicated that the current condition could not be properly rectified back to the 1969 benchmark. This dilemma provided the main impetus for the study documented herein and brought to light two important discoveries: • The traditional storage change calculation contains considerable uncertainty that, when cumulatively added over tens of years, led to a large discrepancy in the accumulated overdraft relative to 1969. • 1969 water level conditions no longer represent a full basin, primarily because of the different pumping and recharge conditions that exist today. Figure 1-1 shows the distribution of groundwater production for WY 1968-69 (upper map) and WY 2004-05 (lower map). Each circle or “dot” represents an active production well for that year, with the size of each dot being proportional to each well’s annual production. Total basin production for WY 2004-05 was only 179,000 af, whereas by WY 2004-05 it had increased to 244,000 af and would have been 70,000 af greater if not for supplemental imported water taken in-lieu of groundwater. By comparing the two production dot maps, heavy increases in pumping are evident in the coastal area since 1969, primarily due to MCWD and IRWD’s Dyer Road Well Field (DRWF). ---PAGE BREAK--- 5 Figure 1-1. Groundwater Pumping Distribution: WY 1968-69 and WY 2004-05 WY 1968-69 GW Production: 179,000 af (af) WY 2004-05 GW Production: 244,000 af (af) ---PAGE BREAK--- 6 In addition to changes in the amount and distribution of pumping since 1969, OCWD managed recharge operations have increased substantially such that much more water is recharged today as compared to 1969. In addition to increased Santa Ana River flows and new recharge basins being put into service in the Anaheim and Orange Forebay areas, new and improved cleaning methods have been implemented to enhance percolation rates, thus increasing the annual volume of water that is recharged annually. Table 1-1 below summarizes the major pumping and recharge differences between WY 1968-69 and WY 2004-05. Table 1-1. Pumping and Recharge Conditions: WY 1968-69 vs. WY 2004-05 WY 1968-69 WY 2004-05 Pumping Total Pumping: 179,000 af Total Pumping: 244,000 af Agricultural Pumping: 34,000 af Agricultural Pumping: 3,400 af No DRWF In-Lieu: 70,000 af No MCWD municipal wells Increased coastal pumping No Newport Beach wells Less Irvine pumping Recharge No Talbert Barrier Enhanced Talbert Barrier No Santiago Pits or Creek Enhanced percolation rates No Kraemer or Miller Basins Basin Cleaning Vehicle No Burris Pit or Five Coves Riverview Basin Since 1969, the largest pumping increases have been in the coastal area while the largest recharge increases have been in the inland Forebay area. Therefore, this redistribution along with increased utilization of the groundwater basin has led to a steeper groundwater gradient or “tilt” from the inland Forebay down to the coast. Because of this increased basin tilt under present conditions, water levels higher than 1969 can be maintained in the Forebay area without exceeding 1969 water levels in the coastal area. Because higher Forebay water levels translate into more basin storage, 1969 no longer represents a full basin condition by today’s standards. In other words, a modern-day full condition could likely accommodate higher water levels than 1969 in the Forebay area, as schematically illustrated in Figure 1-2. A review of historical water level data indicates that many wells in the Anaheim area experienced higher water levels in 1994 than in 1969. Figure 1-3 shows historical water levels for City of Anaheim Well A-27, indicating that in 1994 water levels at that location (adjacent to the south side of Anaheim Lake) were 5-10 feet higher than in 1969. ---PAGE BREAK--- 7 Figure 1-2. Schematic of Groundwater Level Profiles Across the Basin Figure 1-3. Water Level Hydrograph for City of Anaheim Well 27 0 50 100 -50 -100 250 200 150 ELEV (Feet) Coastal Area Anaheim Forebay SW NE 2005 1969 Modern Full 1930 1940 1950 1960 1970 1980 1990 2000 2010 0 50 100 150 200 Water Level Elevation (feet msl) Well A-27 Ground Surface Elev: 231 ft msl Screened Interval: 212 – 287 ft bgs 5 ft ---PAGE BREAK--- 8 2. STUDY OBJECTIVES AND WORK PLAN Objectives of this study were three-fold: 1. Reassess and recommend modifications as necessary to staff’s traditional method for calculating the annual storage change and the accumulated overdraft. 2. Develop a technically-sound full basin water level condition that takes into account current basin management practices. This new full condition would replace 1969 and become the new full benchmark used to calculate the accumulated overdraft or available storage in current and upcoming years. 3. Determine an appropriate basin storage operating range and management goal for long-term basin management purposes. The District Board of Directors approved staff’s work plan in April 2006, and work commenced shortly thereafter. All work was completed by the District’s Hydrogeology Department, with oversight, direction, and review provided by District management. At the request of the Board, project updates were given at the Water Issues Committee meetings as well as the groundwater producers meetings to facilitate the producers’ involvement in the process. The scope of work laid out in the work plan was generally followed. Initially, it was considered that conducting basin model simulations may be beneficial in validating project results. However, after making significant progress in developing a new storage change methodology and new full basin benchmark, it became evident that it was more appropriate to use aquifer parameters and specific knowledge gained from development of the basin model rather than running new model simulations per se. As such, findings enumerated in this report were based on actual water levels observed in the field coupled with a methodology based on aquifer structure and hydraulic parameters defined during development of the basin model. 3. STORAGE CHANGE CALCULATION METHODOLOGY In this section, the District’s traditional storage change calculation is described along with its inherent limitations, followed by a discussion of the development of a new storage change calculation approach and comparison with the traditional method. But first, a conceptual explanation of aquifer storage is explained below. 3.1 Aquifer Storage Concept Aquifers not only transmit groundwater but also provide storage volume, sometimes being referred to as “underground reservoirs.” However, unlike surface water reservoirs, approximately 70 to 80 percent of the aquifer’s volume is occupied by the porous medium, typically consisting of various gradations of sand and gravel as well as ---PAGE BREAK--- 9 silts and clays. This leaves only 20 to 30 percent of the aquifer’s total volume remaining as void space that groundwater can occupy. This percentage of void or pore space is referred to as porosity. Over large areas and depths, the void space within aquifers can occupy huge amounts of water. Within the Orange County groundwater basin, which spans over 300 square miles and is over 2,000 feet deep in some areas, District staff have estimated that approximately 66 million acre-feet of water lies in storage. Unfortunately, the vast majority of this water cannot be feasibly drained from the basin without incurring detrimental impacts. Excessive long-term pumping of basin aquifers without continual replenishment would lead to a lowering of water levels and a reduction in pore pressure, which would lead to seawater intrusion and irreversible compaction of the aquifer, resulting in subsidence of the land surface. The recommended “drainable” storage volume of the basin (without requiring concurrent replenishment) is 500,000 af acre-feet as discussed in Section 6. The parameter used to define the storage capacity of an aquifer is known as the storage coefficient Unlike the porosity which is a measure of the entire void space regardless of whether or not it contains water, the storage coefficient is a measure of how much water can effectively be drained or squeezed out of the saturated pore space. The storage coefficient is defined as the volume of water yielded per unit horizontal area and per unit drop of water table (unconfined aquifers) or piezometric surface (confined aquifers). 3.2 Confined and Unconfined Aquifers A confined aquifer is an aquifer that is confined between two aquitards, which are typically clay or silt layers with low permeability. The water in a confined aquifer cannot freely rise above the overlying clay layer and is under confining pressure. When a well is drilled through the overlying clay layer down into the aquifer, the pressure in the confined aquifer causes the water to rise inside the well (see Figure 3-1) to a level higher than the overlying aquitard. Therefore, water levels measured in wells within confined aquifers – referred to as piezometric levels – may rise and fall but the confined aquifer remains saturated. In a confined aquifer, water is added to or removed from storage primarily through the rearrangement of the unconsolidated sediments via compression or decompression; the compressibility of water contributes significantly less to the storage process. A relatively large piezometric level change in a confined aquifer represents very little change in storage within that aquifer. Storage coefficients for a confined aquifer typically range from 0.01 to as low as 0.00005. An unconfined aquifer is an aquifer in which the water table forms the upper boundary and there is no confining layer above it (see Figure 3-1). That is, the water table can freely rise or fall. Pore space is either filled or drained when the water table rises or falls. Therefore, a unit rise or decline in the water table in an unconfined aquifer represents a relatively large storage volume. For an equivalent water level rise, an ---PAGE BREAK--- 10 unconfined aquifer would exhibit at least 100 times greater storage increase than a confined aquifer. Storage coefficients for unconfined aquifers typically range from 0.01 to 0.3, also referred to as specific yield. In the Orange County groundwater basin, the Shallow aquifer is confined in the coastal and mid-basin areas, commonly referred to as the Pressure Area. The overlying aquitard in the Pressure area thins further inland until it is generally gone. This inland area is referred to as the Forebay area. Since few continuous aquitards exist between the water table and ground surface, it is the “intake” area of the basin where surface water can percolate down to the water table and recharge the aquifers (see Figure 3-1). Figure 3-1. Forebay and Pressure Area Schematic Profile 3.3 Traditional Storage Change Calculation Method Water Level Change Method Traditionally, the storage change calculation was based solely on the water level changes occurring in the Principal aquifer, which is the main production zone in the basin from which approximately 90 percent of basin pumping occurs. Dating back to the 1940s, District staff have prepared a November groundwater contour map of Principal aquifer water levels. By comparing the November contour map to that of the previous year, the annual water level change was then determined. The water level change was then multiplied by a set of storage coefficient values and by the area of the basin to obtain the resulting groundwater storage change for that year. Then, the annual storage change was added to the accumulated overdraft from the previous year to obtain the current accumulated overdraft. 0 50 100 -50 -100 250 200 150 ELEV (Feet) Coastal Area Anaheim SW NE Pressure Area (Confined) Forebay (Unconfined) Vadose Zone Monitoring Well Aquitard Water Table Aquifer ---PAGE BREAK--- 11 Over the years, the overall approach has remained relatively the same, but several refinements were made along the way. In the 1970s, a FORTRAN computer program was developed, referred to as the “Randall Model,” which partially automated the storage change calculation by subdividing the basin into quarter-mile grid cells. The Randall Model computed the storage change calculation grid cell by grid cell. Although this process was somewhat automated, the water level maps had to be manually interpolated to obtain the average water level change for each quarter-mile grid cell. The storage coefficient values for each quarter-mile grid cell were referred to as “Randall” coefficients and are shown in Appendix 1. No documentation exists as to how these storage coefficient values were developed, but they were likely based on review of old well logs throughout the basin. In the early 1990s, with improvements in computer hardware and software, District staff were able to further automate the traditional storage change calculation by using geographical information system (GIS) software to subdivide the basin into smaller, more refined grid cells. By digitizing the hand-drawn water level contour maps into the computer, the water level change at each refined grid cell could be computed without any manual interpolation. However, the overall approach remained the same and still used the same Randall storage coefficient values. Over the last two years, an additional refinement included preparing an end-of-June water level contour map in addition to the annual November contour map. Although the November maps provide a good midpoint between the summer-high and winter-low water level conditions, the June maps coincided better with the District’s water year and fiscal year (July 1 through June 30) for the annual storage change calculation. Water Budget Method For the past 10 to 15 years, the annual storage change calculated using the traditional water level method has been checked using a water budget method (inflows minus outflows equal the change in storage). Therefore, the water budget method uses measured groundwater production and recharge data along with a rainfall-based estimate of incidental recharge (unmeasured recharge less underflow to LA County). The water budget method provides a good check of the storage change estimate from the water level method but is based on an assumed (unmeasured) amount of incidental recharge. In most years, the two methods agree rather closely, and the storage change value from the water level method is generally used. The incidental recharge is then adjusted in the water budget method to exactly match the chosen storage change. Limitations of the Traditional Storage Change Method Although the traditional water level and water budget methods yield similar storage change results in most years, there are some anomalous years in which the two estimates are significantly different. In such years, typically very wet or very dry years, ---PAGE BREAK--- 12 professional judgment must be exercised in determining the official change in storage. This can introduce significant uncertainty into the annual storage change estimate for those years, causing a cumulative effect after several years, which is why the current accumulated overdraft cannot be rectified back to 1969 as discussed in Section 1. The biggest limitation of the traditional method is that it only uses the water level change in the Principal aquifer. Although most groundwater production is from the Principal aquifer, most of the storage change occurs in the Shallow aquifer where it is unconfined in the Forebay area of the basin. Where the Shallow aquifer is unconfined, large storage changes can occur due to the rising or falling of the water table which respectively fills or drains empty pore space, as was discussed in Section 3.2. The Randall storage coefficients used in the traditional method are consistent with those of an unconfined aquifer in the Forebay area and thus are considered as being representative of the Shallow aquifer. Therefore, the traditional method uses Principal aquifer water levels as a surrogate for the Shallow aquifer, assuming that these two aquifers behave identically in the Forebay area. This is largely true in the Anaheim Lake area near the District’s facilities, but in other portions of the Forebay, the Shallow and Principal aquifers often behave differently from one another, as shown in Figure 3- 2. This indicates that these two aquifers are partially hydraulically separated by aquitards in portions of the Forebay and behave differently rather than as a single unconfined aquifer as the traditional method had assumed. It should be pointed out that in earlier years, depth-specific water level data such as that presented in Figure 3-2 was simply not available to discern hydraulic differences between various aquifer zones, and in some areas of the Forebay, there are no noticeable vertical hydraulic differences. It has only been in the last few years through the use of the District’s monitoring well network and development of the basin model that a better understanding of the basin has been gained. Figure 3-2. Water Level Hydrograph for OCWD Monitoring Well SAR-2 2004 2005 2006 2007 0 50 100 150 Water Level Elevation (feet msl) MP1: 141 feet bgs (Shallow Aquifer) MP6: 741 feet bgs (Principal Aquifer) Well SAR-2 (near Burris Pit) ---PAGE BREAK--- 13 3.4 New Three-Layer Storage Change Approach The new three-layer storage change approach uses all three aquifer systems of the basin: the Shallow, Principal, and Deep aquifer systems (see Figure 3-3). The Shallow aquifer generally ranges no deeper than approximately 250 feet below ground surface and overlies the Principal aquifer, which is generally over 1,000 feet thick throughout much of the basin and supports over 90 percent of basin pumping. The Deep aquifer contains colored water in the coastal area and is more than 2,000 feet deep throughout much of the basin. These three aquifer systems, from shallow to deep, are also referred to as aquifer layers 1, 2, and 3. Figure 3-3. Schematic Cross-Section of the Basin Showing Three Aquifer Layers Methodology The new three-layer storage change approach is based largely on the aquifer configuration, structure, and storage coefficient parameter values defined during development of the basin model. Unlike the traditional method, all three of the basin’s aquifer systems are included in this new methodology. Furthermore, the storage coefficient values used in this new method are specific to each aquifer layer and were refined during dynamic or transient calibration of the basin model until the resulting model-generated water levels achieved a close match with observed water level data throughout the basin. The basic formula used to calculate the change in storage is very similar to the traditional method, but now must be carried out for each of the three aquifer layers. The storage change equation is defined as Storage Change = (Water Level Change) x (storage coefficient) x (horizontal area) NON-WATERBEARING FORMATION 0 miles 1,000 2,000 3,000 Seal Beach Yorba Linda Forebay Pressure Area 5 10 15 20 0 Ground Surface PRINCIPAL AQUIFER (Layer 2) DEEP AQUIFER (Layer 3) SHALLOW AQUIFER (Layer 1) Depth (feet) ---PAGE BREAK--- 14 The storage change for each of the three aquifer layers is thereby calculated and the results of all three summed to get the total storage change in the basin. Figure 3-4 shows a schematic cross-section illustrating the three aquifer layers of the basin and how they differ in terms of their respective storage coefficient values. Whereas the traditional method had presumed that the Forebay area behaved entirely as one large unconfined aquifer without any intervening clay layers, our current understanding of the basin is that only the Shallow aquifer in the Forebay area is truly unconfined. As was discussed in Sections 3.1 and 3.2, the majority of the storage change in the basin occurs specifically in the Shallow aquifer within the Forebay area where the rising or falling unconfined water table respectively fills or drains empty pore space. Shallow aquifer storage coefficient values in the Forebay area are approximately 0.1, but in some specific Forebay locations can be as high as 0.25, which is approximately equivalent to the porosity of the sediments at the water table/vadose zone interface. Figure 3-4 illustrates how the Shallow aquifer is confined in the Pressure area of the basin. By definition, the Pressure area ends where the water level drops below the elevation of the overlying aquitard and/or where the aquitard no longer exists. In the Pressure area, the Shallow aquifer storage coefficient values are approximately 0.004, or approximately 25 times smaller than in the unconfined Forebay area. This means that for a given water level change in the Pressure area, the resulting change in storage would be 25 times less than for that same water level change observed in the unconfined Forebay area. As shown in Figure 3-4, the Principal aquifer is largely separated from the overlying Shallow aquifer by an extensive aquitard in the coastal and mid-basin areas. In the inland Forebay area, this intervening aquitard becomes intermittent but does not vanish completely, causing some hydraulic separation from the Shallow aquifer while still allowing large amounts of water to migrate downward into the Principal aquifer. As schematically shown in Figure 3-4, Principal aquifer water levels frequently differ from those in the Shallow aquifer due to the hydraulic separation, as was also shown in Figure 3-2 for multi-depth monitoring well SAR-2 near Burris Basin, where observed water levels in the Principal aquifer are noticeably lower than in the Shallow aquifer. The Principal aquifer is thus considered to be semi-confined in the Forebay area, with storage coefficient values of approximately 0.01, which is at least 10 times less than in the unconfined Shallow aquifer. The Deep aquifer is generally confined throughout the entire basin and is separated from the overlying Principal aquifer by an extensive aquitard that thins somewhat in the Forebay area but remains laterally extensive. Therefore, since water level changes in the Deep aquifer represent pressure responses and thus do not involve filling or draining of pore space, storage coefficient values are typically small at approximately 0.001 throughout the entire basin. ---PAGE BREAK--- 15 The storage coefficient values shown in Figure 3-4 and discussed above are typical values for each of the three aquifer layers. The actual storage coefficients used in the storage change calculation not only vary for each aquifer layer but also vary spatially across the basin in both the Pressure and Forebay areas. From the basin model calibration, the different storage coefficient values within each aquifer layer are subdivided into detailed zones. For reference, these zonal storage coefficient maps are included in Appendix 2. These storage coefficient values in the Forebay area of the Shallow aquifer are generally consistent with the Randall coefficients traditionally used. Figure 3-4. Schematic cross-section showing storage coefficients values The other component of the storage change formula not yet discussed is the water level change. To obtain the water level change involves constructing water level contour maps for each of the three aquifer layers, both for the previous and current year. Preparation of the water level contour maps for each aquifer layer requires a considerable level of interpretation of the actual data points as well as interpolation between data points. The reported water level data is not always 100 percent accurate and must be reviewed on a well-by-well basis as the contour map is being constructed. Reasons for disqualifying or adjusting observed water level data during the contouring process may include: • A static water level from a production well may have been measured only minutes after shutting off the well pump; • Erroneous water level field measurement bad equipment); 0 1,000 200 Depth (Feet) Pressure Area Forebay 1,500 Anaheim Coastal Area Shallow Aquifer Principal Aquifer Deep Aquifer Unconfined Semi-Confined Confined Confined Confined Confined S~0.004 S~0.002 S~0.001 S~0.1 S~0.01 S~0.001 S~0.004 S~0.002 S~0.001 S~0.1 S~0.01 S~0.001 ---PAGE BREAK--- 16 • Water level measurement taken too early or too late (for the June and November contour maps, attempt to measure all water levels within a two-week window); • Wells are screened at different depths and some wells are screened across multiple aquifers such that water level data not entirely representative of any one aquifer layer being contoured. In addition to the above reasons for screening the observed water level data points, extreme care and consistency must be exercised from one year to the next when contouring and interpolating between data points, especially in sparse areas lacking sufficient data to definitively define the shape of the contours. Barring any new wells or data, water levels should be similarly interpreted in these areas from year to year so that false storage changes are not artificially created. Knowledge of the aquifer’s characteristics, presence of geologic faults, regional flow regime, and vertical relationship with the other aquifers have proven useful in determining the contour patterns in a given area. Of the three aquifer layers, the Principal aquifer has the best water level data coverage thanks to more than 200 large system production wells monitored by each respective groundwater producer, as well as District monitoring wells throughout the basin. Historically, this predominance of available water level data for the Principal aquifer and lack thereof for the Shallow and Deep aquifers is a likely reason that the traditional storage change method only considered the water level change in the Principal aquifer. Much more water level data exists today for the Shallow aquifer than in the past, primarily due to the District’s network of monitoring wells, many of which monitor multiple aquifer zones at one well site, helping to decipher the vertical relationship between the Shallow and deeper aquifers and their degree of hydraulic connection. Since the majority of the storage change in the basin occurs in the unconfined portion of the Shallow aquifer within the Forebay area, the constructed water level contours are of utmost importance in those inland areas. Unfortunately, data is sparse in a few of these outlying areas of the basin. Therefore, to increase the accuracy of the Shallow aquifer contour maps and thus the accuracy of the storage calculation, approximately six new shallow monitoring wells are recommended to fill data gaps in the areas of Buena Park, Costa Mesa, Fullerton, Orange, Irvine, and Yorba Linda. Figure 3-5 shows the approximate desired locations for these six proposed wells. Figure 3-5 also shows the water level contours for the Shallow aquifer for June 2006. Just as for the other two aquifer layers, these contours where hand drawn based on observed water level data from wells screened in the Shallow aquifer (shown in light gray in Figure 3-5). The hand-drawn contours were then digitized into the computer for calculation purposes. Note that the contours were drawn out to the boundary of the basin model layer 1 which extends into LA County, but during the storage calculation process the LA County portion is excluded. ---PAGE BREAK--- 17 Figure 3-5. June 2006 Shallow Aquifer Groundwater Elevations and Proposed Wells GIS Application for Three-Layer Storage Change Calculation A new GIS application was developed and programmed to automate the new three- layer storage change calculation utilizing the digitized water level contour maps for each aquifer layer as well as the storage coefficient values from the basin model. The new GIS application consists of a series of steps governed by programs written in the AML scripting language within the Arc/Info environment. A detailed description of these steps, along with all the AML codes written for this application, is included in Appendix 4. The digitized water level contours are converted into GIS compatible files (grids) at the same refined resolution as the basin model input parameters, essentially subdividing the entire basin into 500-foot square grid cells. The GIS application then carries out the storage change formula one grid cell at a time for each aquifer layer, calculating the water level change between the two years in question and multiplying by the storage Proposed Shallow Aquifer Monitoring Well Proposed Shallow Aquifer Monitoring Well ---PAGE BREAK--- 18 coefficient and horizontal area of the grid cell. Then, the storage change of all grid cells is summed for each layer. The total change in storage is then the corresponding sum of all three aquifer layers. When calculating the storage change at each grid cell, the GIS application must check to determine if the conditions are confined or unconfined. Generally, the Principal and Deep aquifers are typically confined, but the Shallow aquifer is confined in the Pressure area and unconfined in the Forebay area, with the dividing line between these two areas being dependent upon the actual water level elevations at that time. If the water level is above the top of the aquifer layer (per the basin model layer elevations), then a confined storage coefficient is used for that grid cell; otherwise, if the water level is below the top of that aquifer layer, then a larger unconfined storage coefficient is used. To further complicate matters, the water level change in question from Year 1 to Year 2 may cause a given grid cell in the Shallow aquifer to switch from confined under Year 1 conditions to unconfined under the Year 2 conditions, or vice versa. The GIS application handles this type of condition by subdividing the water level change into two components: a confined portion and an unconfined portion. This is illustrated in the sketch and “pseudo-code” algorithm that was written for this application prior to formal programming of the GIS application (Appendix The new GIS application for the three-layer storage change calculation was thoroughly tested and necessary refinements were made to the AML codes. Water level change and storage change calculations were hand checked and verified at individual grid cells having both confined and unconfined conditions. Also, the storage change results for each aquifer layer were verified to be identical in magnitude but opposite in sign if switching the order of what is predefined as Year 1 or Year 2. For example, if the storage change from Year 1 to Year 2 was calculated to be 10,000 af, then the storage change from Year 2 to Year 1 calculates to be exactly -10,000 af. Testing the Three-Layer Method vs. the Traditional Method Test Case 1 compared the new three-layer storage change calculation to the traditional method using the annual period November 2004 to November 2005. This first test case represented an extremely wet year with record-setting rainfall and a huge storage change of +187,000 af using the traditional method with the existing November contour maps of the Principal aquifer. Using the new three-layer approach led to a storage change of +147,000 af for the same period. The rather large discrepancy of 40,000 af in Test Case 1 is primarily due to the inaccuracy of the traditional method presumption that Principal aquifer water levels behave identically to Shallow aquifer water levels in the Forebay area. As was shown in previous sections, this is not always the case and was especially not the case during 2004-05 when the Principal aquifer rose much more than the Shallow aquifer in most Forebay locations. ---PAGE BREAK--- 19 Figure 3-6 shows water levels for multi-depth monitoring well SAR-2 near Burris Basin in the Anaheim Forebay area. Notice that the water level change from November 2004 to November 2005 in the Principal aquifer zone was more than double that for the Shallow aquifer zone at that location. Since this was the case throughout much of the Forebay area, the traditional method overestimated the storage change by using Principal aquifer water levels as a surrogate for the Shallow aquifer. Figure 3-6. November 2004-05 Water Level Change at Monitoring Well SAR-2 Test Case 2 compared the new three-layer method to the traditional method for the most recent water year, June 2005 through June 2006. This water year was chosen because it not only represented the most recent conditions but it was also an approximately average rainfall year in contrast to the extremely wet year in Test Case 1. As was mentioned in previous sections, care was exercised to maintain consistency of how the water level data was interpreted and hand contoured for both of these years to prevent any false or “manufactured” water level changes between the two conditions. For Test Case 2, the traditional method yielded a storage change of +52,000 af, whereas the new three-layer method yielded a higher storage change of +66,000 af. The two methods yielded much closer results for this average hydrology year, indicating that the traditional method is at least “in the ballpark” during more typical years when water levels are not as drastically rising or falling. In these closer-to- average years, the traditional method presumption that Principal aquifer water levels behave similarly to the Shallow aquifer is not grossly inaccurate. However, since the new three-layer approach is more comprehensive and utilizes all three aquifer layers, it 2004 2005 2006 2007 0 20 40 60 80 100 120 Water Level Elevation (feet msl) OCWD Monitoring Well SAR-2 (near Burris Pit) 44 ft 18 ft MP1: 141 feet bgs (Shallow Aquifer) MP6: 741 feet bgs (Principal Aquifer) (near Burris Basin) ---PAGE BREAK--- 20 represents a technical improvement upon the traditional method and is the preferred approach. Figure 3-7 summarizes the results from both test cases 1 and 2 and schematically shows the storage change per aquifer layer for the three-layer method. As expected and as was discussed in earlier sections, the majority of the storage change occurred in the Shallow aquifer. The majority of basin pumping (over 200,000 afy) occurs from the Principal aquifer, which is continuously being fed by the Shallow aquifer, which in turn is being fed by the District’s recharge activities (typically over 200,000 afy). If basin pumping exceeds total recharge over a given year, then the Principal aquifer draws more water out of the Shallow aquifer than what is coming in from recharge, resulting in an annual storage decrease in the Shallow aquifer. Conversely, if recharge exceeds basin pumping over the course of a year (especially in a wet year), then more recharge is entering the Shallow aquifer than what is flowing down into the Principal aquifer, causing Shallow aquifer water levels to rise and a resulting storage increase. Figure 3-7. Summary of Traditional vs. Three-Layer Storage Change Results Shallow Aquifer Principal Aquifer Deep Aquifer Traditional Method Three-Layer Method (Nov-04 to Nov-05) (Jun-05 to Jun-06) +187,000 af +147,000 af +52,000 af +66,000 af Test Case 1 Test Case 2 57,000 5,000 4,000 115,000 21,000 11,000 ---PAGE BREAK--- 21 4. NEW FULL BASIN BENCHMARK Since a new three-layer method was developed and tested for calculating the change in storage, a new full basin benchmark must be defined for all three aquifer layers so that the accumulated overdraft can ultimately be calculated. In Section 1, it was shown that 1969 water levels no longer represented a full basin given the significantly different pumping and recharge conditions that exist today. In fact comparing the November 1969 water level contour map to the recent June 2006 Principal aquifer contour map shows that in much of the Forebay area, Principal aquifer water levels are already higher in June 2006 than they were in November 1969 when the basin had historically been considered full (see Figure 4-1). The Irvine Forebay area was over 80 feet higher in June 2006 than 1969 due to reduced agricultural pumping over the years. As was discussed in Section 1, because of increased utilization of the groundwater basin, i.e., increased pumping and recharge, higher Forebay water levels can be achieved while coastal water levels remain lower, resulting in a steeper basin gradient. Figure 4-1. Principal Aquifer Water Level Change: November 1969 to June 2006 Nov 69 to Jun 06 1969 data not available in this area ---PAGE BREAK--- 22 4.1 Assumptions and Methodology A water level contour map representing a reasonable full condition was developed for the Shallow, Principal, and Deep aquifers. The resulting full water levels represent a “snapshot” of a peak high water level condition throughout the basin that could possibly be exceeded but with potentially detrimental impacts. Defining how high basin water levels can rise before being considered full was largely based on a comprehensive review of relatively recent historical high basin conditions that occurred approximately in 1994 and 2006. The high basin conditions that occurred in 1969 and 1983 were briefly reviewed but were deemed of less direct value since basin pumping and recharge patterns were significantly different then. Much of the groundwater basin achieved historical highs during 1994, with the coastal area peaking in the winter and the Forebay area in late spring or early summer. A similar lag in the seasonal timing of the coastal and Forebay area water level peak was observed during the recent high condition of 2006. Typically after a very wet winter, surplus storm runoff impounded behind Prado Dam is still being released for OCWD recharge operations well into the summer months, thus increasing Forebay recharge amounts, which in turn raise Forebay water levels at a time when coastal water levels are already beginning to decline in response to summer pumping. However, also during wet years, MWD has surplus water; thus, taking additional imported water in-lieu of groundwater pumping can extend into the summer months, which would prevent or delay coastal water levels from declining. Therefore, for the purposes here of defining a basin-wide full condition, it is assumed that water levels can concurrently peak to a full condition throughout the basin. The full condition that was developed for all three aquifer layers represents the highest achievable water levels throughout the basin under realistic present-day operating conditions without incurring any regional-scale detrimental impacts. In general, coastal water levels were assumed to be at or very near the 1994 and 2006 winter highs, whereas the Forebay area was assumed to be at or above the 1994 and June 2006 highs. In so doing, the full basin coastal water levels were high enough to be protective against seawater intrusion but not unnecessarily high to where shallow groundwater seepage could become an issue. In the Forebay area, full basin water levels were generally well below ground surface and at or near the bottom of deep recharge basins (as occurred in June 1994). Therefore, in the Forebay area, water levels any higher than this full condition may be physically possible but would likely impact recharge operations and lead to considerable mounding problems. Other assumptions that define the new full basin condition are enumerated below. 1. Full basin flow patterns (shape of the water level contours) are representative of present-day pumping and recharge conditions (except where specifically noted) and thus are largely based on and consistent with actual water level contour maps constructed for the recent high conditions of January 2006 and June 2006. ---PAGE BREAK--- 23 2. Water levels in the Irvine Sub-basin were at historical highs during 2006 because of the extremely wet year 2004-05 and reduced Irvine Company agricultural pumping. The new full condition in the Irvine Sub-basin is thus based on this recent high condition, which inherently then excludes the Irvine Desalter Project (IDP). The IDP will significantly lower Irvine area water levels for many years to come, but the regional drawdown and resulting water levels in that area are uncertain and may take several years to stabilize. Previous basin model scenarios including IDP pumping estimated that approximately 50,000 af of storage decline in the Irvine Sub- basin could occur after 20 years of full-scale IDP pumping. With this in mind, the new full condition will not likely be achievable in the Irvine Sub-basin after the IDP goes on-line. 3. Based on the earlier assumption that this new full condition is protective against seawater intrusion, full basin water levels in the MCWD area were based on the historical high of 1994 rather than the somewhat lower water levels during the 2006 high condition. The 1994 water levels in the MCWD area were higher than in 2006 because the MCWD colored water project was not yet active in 1994. Therefore, the new full basin water levels in that immediate area inherently assume no MCWD colored water project no pumping from Well MCWD-6) in order to define a condition sufficiently protective against seawater intrusion. 4. Full basin water levels in the immediate area of the Talbert Barrier were adjusted higher than recent high conditions to account for the GWR Phase 1 barrier expansion soon to be on-line. Some of these new injection wells, including the four wells along the Santa Ana River just north of Adams Avenue, are already on-line and thus the observed water level rise due to these wells was used in the full basin condition. 5. Full basin water levels were raised higher than either of the historical highs of 1994 or 2006 in areas where other near-term recharge projects are already planned, including La Jolla Basin and Santiago Creek recharge enhancements. However, especially in the case of Santiago Creek, full basin water levels were kept sufficiently below ground surface and known landfill elevations. 4.2 Shallow Aquifer Full Basin Water Level Map Full basin water levels for the Shallow aquifer were based largely on the historical high water levels observed in 1994 and 2006. Only wells with a screened interval generally in the range from 100 to 250 feet below ground surface (depending on the specific area) were used to ensure that these wells were representative of the Shallow aquifer. This depth restriction excludes most large system production wells. Therefore, the majority of wells used to construct the Shallow aquifer full basin water level map were District monitoring wells, along with some small system and domestic wells having sufficient water level histories. Fortunately, the majority of the District’s monitoring wells were constructed early enough so as to catch the 1994 high-basin condition. ---PAGE BREAK--- 24 Prior to this study, Shallow aquifer water levels were not regularly contoured, but Shallow aquifer contour maps (basin model layer 1) had been constructed during basin model development and much was learned about the hydraulic characteristics and flow patterns of the Shallow aquifer. Subsequently for testing the new three-layer storage change method described in Section 3, water level contour maps were constructed for all three aquifer layers using observed data for both June 2005 and June 2006. Fortunately, June 2006 also represented a high-basin condition from which to use as a base for making adjustments up to the new full condition. In the coastal and mid-basin areas, high water levels that peaked in January 2006 were generally adhered to and used for the full condition in those areas. This represented a condition high enough to be protective of seawater intrusion, but anything appreciably higher could potentially result in shallow groundwater seepage problems in low-lying areas. In the immediate area surrounding portions of the Talbert Barrier, the observed January 2006 water levels were adjusted upward approximately 5 feet to account for increased injection from new GWRS Phase 1 injection wells. In the area surrounding the GWRS treatment plant site where considerable construction dewatering was occurring during January 2006, full water levels were based on earlier historical highs that were nearly 15 feet higher than January 2006 in this immediate area. In the Forebay area, full basin water levels were generally set from 0 to 15 feet above the higher of the two historical peaks that occurred in June 1994 and June 2006. The magnitude of the upward adjustment between 0 and 15 feet depended on conditions at each well location and was most significantly influenced by the relative depth of the water table from ground surface. Since relatively little pumping occurs from the Shallow aquifer, the unconfined water table in the Forebay area is largely considered to be a subdued reflection of topography, with the exception of directly beneath recharge basins where the Shallow aquifer water table tends to rise in response to percolation. From analysis of the Forebay historical highs (June 1994 and/or June 2006), Shallow aquifer water levels generally peak at an elevation that corresponds to a depth of approximately 50 to 60 feet below ground surface. Therefore, when setting the full basin water level elevations at various well points and especially in areas where little or no data existed, the 50- to 60-foot depth to water rule of thumb was generally maintained. Since the majority of the storage change in the basin occurs in the Shallow aquifer within the Forebay area, the full basin water level condition in this area is crucial. A discussion of the full basin Shallow aquifer water level adjustments for specific regions of the Forebay is described below. At Anaheim Lake and Kraemer Basin, full basin water levels were set at June 1994 observed levels with no upward adjustment since these levels were essentially at or even a couple feet above the deepest portion of Anaheim Lake, which is approximately 50 to 60 feet deep (see Figure 4-2), which is consistent with the depth to water rule of thumb mentioned above. Water levels any higher at this location, if even achievable, would likely impede percolation from these basins and thus would not be desirable. ---PAGE BREAK--- 25 Figure 4-2. Full Basin Water Level at Anaheim Well 27 At Santiago Pits, full basin water levels were set at the historical high of March 1993 (just higher than June 1994) with no upward adjustment. This same identical high was reached but not exceeded more recently in June 2005 after the extremely wet winter of 2004-05. Having the observed water levels peak at the same exact same level in 1993 and 2005 may likely indicate that this repeatable historical high may represent the highest physically achievable water level for this area. In the Anaheim/Fullerton area west of the District’s spreading grounds, full basin water levels were set 10 to 15 feet higher than the new historical high of June 2006. Water levels in June 2006 exceeded the previous historical high of June 1994 and appear to still be on an upward trend. The upward adjustment of 10 to 15 feet from the June 2006 observed condition once again brought the water table up to approximately 50-60 feet from ground surface. Along the Santa Ana River of Lincoln Avenue, full basin water levels were set 5 to 10 feet higher than the new historical high of June 2006, which exceeded the previous high of June 1994 in this area as well. The upward adjustment of 5 to 10 feet above the historical high once again brought the full condition up as shallow as 40-50 feet from ground surface, likely being influenced by the recharge from the Santa Ana River and Burris Basin. This full level also corresponds approximately to the bottom elevation of Burris Basin, analogous to the full level adjacent to Anaheim Lake. 1930 1940 1950 1960 1970 1980 1990 2000 2010 0 50 100 150 200 250 Water Level Elevation (feet msl) Ground Surface “Full” Water Level = Jun-94 Anaheim Lake 50-60 ft Well A-27 (adjacent to Anaheim Lake) Screened Interval: 212–287 ft bgs ---PAGE BREAK--- 26 In the Irvine Forebay area, full basin water levels were set within 5 feet of the historical high, which either occurred in 1994, 1999, or 2006 depending on the exact location within this general area. Recall from the previous section that this new full condition is prior to full-scale IDP pumping. Although the majority of IDP pumping will be from the Principal aquifer, Shallow aquifer water levels will likely also decline. Finally, in the mid-basin Pressure area, full condition water levels were modestly adjusted upward 5 to 10 feet from the new historical high of June 2006, which again significantly exceeded the previous high of June 1994. This slight upward adjustment maintains a reasonable gradient from the coast to the upwardly adjusted full water levels in the Anaheim Forebay area. After making all the full condition water level adjustments at monitoring well points in the various areas described, the resulting full water levels were plotted on a map and hand contoured similarly to the observed water levels of June 2006. In fact, the June 2006 contour map was used as a guide or backdrop on the light table while contouring the full condition to ensure consistency, especially in outlying areas lacking data. Figure 4-3 shows the resulting full water level contour map constructed for the Shallow aquifer. Also shown for reference is the June 2006 Shallow aquifer contour map directly below it. Note the similarity in the shape of the contours between the two maps. The various well points screened in the Shallow aquifer that were used for constructing these contour maps are shown in light gray. The red boundary represents the basin model layer 1 boundary which represents the extent of the Shallow aquifer along the mountain fronts where the aquifer terminates and on the western boundary represents an arbitrary cutoff 5 miles into LA County. Contouring the water levels into LA County adds confidence to the shape of the contours in west Orange County and at least qualitatively indicates the direction of flow across the county line. Figure 4-4 shows the same two Shallow aquifer water level conditions (Full and June 2006), but in units of depth to water below ground surface rather than elevation. As was discussed above, notice that much of the Forebay area is within the 40 feet below ground surface or greater range since the Shallow aquifer water levels generally follow ground surface topography where the aquifer is unconfined (Forebay), except near recharge facilities where the depth to water is more shallow due to percolation raising the water table. The depth to water also becomes shallower in the Pressure area of the basin where the Shallow aquifer is confined. However, these “water levels” are actually pressure or piezometric levels since the water is confined or trapped below the overlying aquitard. Water can only rise to this elevation if a well is drilled through the aquitard down into this aquifer or if the aquitard is thin or discontinuous. Notice that there is a large area in Irvine where the piezometric level is actually above ground surface in both the observed June 2006 and Full condition. This area has historically experienced artesian conditions when basin levels are relatively high. ---PAGE BREAK--- 27 Figure 4-3. Shallow Aquifer Groundwater Contours: Full Basin and June 2006 ---PAGE BREAK--- 28 Figure 4-4. Shallow Aquifer Depth to Water: Full Basin and June 2006 Full Basin Shallow Aquifer June 2006 Shallow Aquifer ---PAGE BREAK--- 29 4.3 Principal Aquifer Full Basin Water Level Map As with the Shallow aquifer, full basin water levels for the Principal aquifer were also based on the historical high water levels observed in 1994 and 2006. Wells with a screened interval generally within a range between 300 to 1,000 feet below ground surface (depending on the specific area) were used to represent the Principal aquifer. This depth interval includes most large system production wells, which along with District monitoring wells, were used to construct the Principal aquifer full basin water level map. Prior to developing the full basin condition for the Principal aquifer, the high-basin water level condition of January 2006 was analyzed and contoured to determine the flow patterns and contour shapes for a most recent, near-full, actual condition. In subsequent months, observed water levels in the Forebay area increased further to a new historical high in June 2006, whereas in the coastal area January 2006 remained a historical high. In the coastal area, full basin water levels were generally set at or within 5 feet of the observed peak January 2006 water levels, as was also done for the Shallow aquifer. In fact, this was the case for the majority of the Pressure area, where January 2006 water levels were noticeably higher than the previous high of 1994 (see Figure 4-5). Figure 4-5. Full Basin Water Level at Santa Ana Well 21 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 -80 -60 -40 -20 0 20 40 60 80 Groundwater Elevation (ft msl) Ground Surface “Full” Basin Water Level = Jan 06 Production Well SA-21 Screened Interval: 400–960 ft bgs (Principal Aquifer) ---PAGE BREAK--- 30 The exception to using January 2006 water levels for the full condition in the Pressure area was in the MCWD area where the high condition of April 1994 was used. At this location, January 2006 water levels were 15 to 20 feet lower than April 1994 because of current pumping from the MCWD colored water project that did not exist in 1994. As was mentioned in the Section 4.1 assumptions, since the full condition must be sufficiently high in the coastal area to be protective of seawater intrusion, the older but higher April 1994 water levels were used in this area for the full condition even though it is not representative of present-day pumping in this immediate area (see Figure 4-6). Figure 4-6. Full Basin Water Level at Mesa Consolidated Water District Well 2 Throughout most of the Irvine Sub-basin, January 2006 represented a historical high similar to the rest of the Pressure area. Thus, full basin water levels in Irvine were also set within 5 feet of observed January 2006 levels. However, in north Irvine near the Santa Ana mountain front, 1999 water levels were used since they were nearly 15 feet higher than January 2006 in that immediate area. In the Anaheim and Orange Forebay areas, full basin water levels were generally set at or within 5 feet of the historical high that occurred during March through June of 1994 depending on the exact location. For the majority of the Forebay area, 1994 still represented a historical high for the Principal aquifer, higher than January or June 2006. Although the full water levels were based on different historical highs in different areas of the basin (coastal vs. inland), resulting gradients and flow patterns were reasonable and similar to those contoured for the observed data of June 2006 (see Figure 4.7). 1980 1985 1990 1995 2000 2005 2010 -120 -100 -80 -60 -40 -20 0 20 40 Groundwater Elevation (ft msl) Ground Surface “Full” Basin Water Level = April 94 Production Well MCWD-2 Screened Interval: 300–650 ft bgs (Principal Aquifer) ---PAGE BREAK--- 31 Figure 4-7. Principal Aquifer Groundwater Contours: Full Basin and June 2006 ---PAGE BREAK--- 32 4.4 Deep Aquifer Full Basin Water Level Map For the Deep aquifer, the main data source for developing the full basin condition was water level data from the District’s deep multi-port monitoring (Westbay) well network. Approximately two-thirds of these 56 wells were sufficiently deep and in appropriate locations overlying the Deep aquifer. Depending on the specific location, the monitoring ports of these wells that tap the Deep aquifer generally range from approximately 1,500 to 2,000 feet below ground surface. In addition to the District’s deep monitoring wells, a few other scattered well points that tap the Deep aquifer were used, such as two deep monitoring wells owned by the Water Replenishment District in LA County (very close to the county line). The new full condition for the Deep aquifer was predominantly based on the historical high that occurred in 1994. Throughout the basin, the recent June 2006 Deep aquifer water levels were still well below the historical high of 1994, likely due to the IRWD Deep Aquifer Treatment System (DATS) Project which began pumping approximately 8,000 afy of colored water in December 2001 from this otherwise little-used zone. Also, there was no MCWD colored water project yet in 1994. Fortunately, most of the District’s deep monitoring wells are old enough to have captured the historical high condition of 1994. It is somewhat speculative as to how high the piezometric level of the Deep aquifer can rise. Therefore, full water levels were conservatively adjusted only 0 to 5 feet higher than the observed historical peak that occurred April to June of 1994. In so doing, the observed vertical piezometric head difference between the overlying Principal aquifer and the Deep aquifer was maintained. Throughout most of the basin, Deep aquifer piezometric levels typically ranged from 10 to 30 feet higher than the more heavily pumped Principal aquifer, except in the furthest inland locations near the mountain front and near recharge facilities where the Deep aquifer levels are actually lower than the Principal aquifer due to being more vertically removed from surficial recharge. While contouring the resulting Deep aquifer full basin piezometric levels (also referred to as water levels for simplicity), the Principal aquifer full condition contour map was used as a backdrop on the light table to ensure that the Deep aquifer full contours maintained the vertical head difference discussed above. Also, in areas lacking data, the contours were drawn with similar patterns as those predicted during basin model calibration. Figure 4-8 shows the resulting contour maps for both the new full condition and also June 2006 for comparison. The contour shapes are quite similar for both maps except in the area near the aforementioned DATS wells. The Full map assumes no DATS pumping since it was based on the historical high water levels of 1994, whereas the June 2006 map shows a relatively deep pumping depression in that immediate area. However, due to the confined nature of the Deep aquifer, the storage coefficients of this zone are very small (see Appendix 2) and thus even a relatively large water level difference leads to a small storage change. ---PAGE BREAK--- 33 Figure 4-8. Deep Aquifer Groundwater Contours: Full Basin and June 2006 ---PAGE BREAK--- 34 5. ACCUMULATED OVERDRAFT FROM NEW FULL CONDITION The accumulated overdraft is the amount of storage capacity below full, sometimes referred to as dewatered storage or available storage capacity. In various literature, overdraft often has a negative connotation implying that a basin is in a steady state of decline or has been drawn-down below some critical threshold to where negative impacts such as subsidence and seawater intrusion begin to occur. In this report, use of the term “accumulated overdraft,” which is defined in the District Act, is not intended to have any negative connotation and is strictly used as a measure of available basin storage below the new full benchmark or zero-overdraft condition established in Section 4. 5.1 Accumulated Overdraft as of June 30, 2006 The new three-layer storage change methodology was used to calculate the accumulated overdraft for June 2006. Three groundwater contour maps (one for each aquifer layer) representing June 30, 2006 had already been constructed for testing the new three-layer approach described in Section 3. For the storage change calculation, Year 1 was set to the new full water level condition and Year 2 was set to the June 2006 water level condition. The resulting change in storage from the new full condition to June 2006 was -135,000 af, or in other words, the accumulated overdraft as of June 30, 2006 was 135,000 af below the new full benchmark. The breakdown per aquifer layer is schematically shown below in Figure 5-1. Figure 5-1. Three-Layer Accumulated Overdraft for June 2006 Full -135,000 AF 0 AF Shallow Aquifer: 110,000 AF Jun-06 Principal Aquifer: 20,000 AF Deep Aquifer: 5,000 AF ---PAGE BREAK--- 35 To put the Shallow aquifer storage change from the full condition (110,000 af) into perspective, Shallow aquifer water levels in most of the Forebay area were approximately 15 feet higher in the full condition as compared to June 2006 (Figure 5- In the coastal area, full water levels were only about 5 feet higher than June 2006. And since much more storage change occurs in the Forebay than the Pressure area per foot of water level change, nearly all of the Shallow aquifer storage change from full to June 2006 occurred in the Forebay area. Therefore, in general, a 15-foot Shallow aquifer water level change throughout the Forebay caused approximately 100,000 af of storage change. Detailed water level change maps for June 2006 to the new full condition for all three aquifer layers are shown in Appendix 3. Figure 5-2. Average Shallow Aquifer Water Level Difference from June 2006 to Full 5.2 Accumulated Overdraft as of June 30, 2005 Using the new three-layer storage change method, the accumulated overdraft was calculated for June 2005 by directly comparing to the new full benchmark once again. In the storage change calculation, Year 1 was set to the new full water level condition and Year 2 was set to the June 2005 water level condition. The resulting total change in storage from the new full to June 2005 was -201,000 af, or in other words, the accumulated overdraft was 201,000 af below the new full benchmark. Forebay Pressure Area +15 +5 or less +25 Shallow Aquifer Water Level Increase (ft) from Jun 2006 to Full Condition ---PAGE BREAK--- 36 The June 30, 2005 accumulated overdraft for each aquifer layer was as follows: Shallow aquifer: 166,000 af Principal aquifer: 25,000 af Deep aquifer: 10,000 af Total: 201,000 af The difference between the June 2005 and June 2006 accumulated overdraft was 66,000 af, which represents the annual increase in storage from July 1, 2005 through June 30, 2006 (see figure 5-3). As a check, this storage change of 66,000 af was exactly the same as that calculated directly using the new three-layer method with Year 1 as June 2005 and Year 2 as June 2006 (see previous Figure 3-7). Therefore, this confirmed that the new three-layer approach yields exactly the same results summing the annual storage change over multiple years or calculating the storage change using the start and end of the multiple year period. In addition, the new method has been shown to yield the same identical storage change, but opposite in sign, when reversing the order of Year 1 vs. Year 2. Figure 5-3. Accumulated Overdraft Schematic for June 2005 and June 2006 5.3 Historical vs. New Accumulated Overdraft Estimates The new accumulated overdraft estimate of 201,000 af for June 2005 is 29,000 af less than the traditional method estimate of 230,000 af published in the 2004-05 OCWD Engineer’s Report. This discrepancy is relatively minor when considering the major differences between the traditional single-layer and new three-layer storage change methods and also their two corresponding different full basin benchmarks. Since the historical accumulated overdraft levels are all relative to the 1969 condition as being the 0 AF New Full Benchmark 0 AF New Full Benchmark - 135,000 AF June 30, 2006 - 201,000 AF June 30, 2005 - 201,000 AF June 30, 2005 66,000 AF ---PAGE BREAK--- 37 zero-overdraft benchmark, the two new accumulated overdraft estimates for June 2005 and June 2006 are plotted on the same familiar historical overdraft graph in Figure 5-4. However, this graph has been divided at the June 2005 line due to the two different zero-overdraft benchmarks of 1969 water levels and the new full condition. Figure 5-4. Historical and New Accumulated Overdraft 5.4 Implementation of New Three-Layer Storage Change Method To prevent or minimize any accumulation of potential discrepancy from year to year when implementing this new storage change method, it is important to follow the steps enumerated below. 1. Hand-contour water levels collected on or about June 30 for each of the three aquifer layers, maintaining consistency with how the water level data is interpreted from year to year, unless new well data in a specific area causes a different interpretation. 2. Use the GIS to calculate the water level change and corresponding storage change from the three-layer full benchmark to the current June condition. The resulting storage change below the full condition represents the accumulated overdraft for June of that year. Three-Layer New Full 0 100,000 200,000 300,000 400,000 500,000 Jun-69 Jun-74 Jun-79 Jun-84 Jun-89 Jun-94 Jun-99 Jun-04 Jun-09 Accumulated Overdraft (AF) New Jun-06 135,000 AF New Jun-05 201,000 AF Old Jun-05 230,000 AF Single-Layer Traditional Full (1969) Jun-05 ---PAGE BREAK--- 38 3. Subtract the previous year’s accumulated overdraft from the current year to obtain the annual change in storage for that water year. 4. This step is a quality control check. Use the three-layer storage change method once again to calculate the water level change and storage change from the previous June (Year 1) to the current June (Year This storage change should exactly equal the storage change calculated in Step 3. 5. Calculate incidental recharge for that water year by inputting the annual storage change estimate from Step 3 or 4 (if they are the same) into the water budget method described in Section 3.3. The resulting incidental recharge should be reasonable given the annual rainfall for the year in question; otherwise, additional error checking should be done for the water budget terms as well as the input data for the storage change calculation. It should be pointed out though that incidental recharge is not solely a function of rainfall because the flow across the LA County line – along with all other unknown inflows and outflows – is lumped into the incidental recharge term. That being said, incidental recharge for a somewhat typical year with average rainfall is thought to be approximately 60,000 afy but could vary by upwards of 20,000 af based on changes in outflow to LA County, which unfortunately is difficult to quantify. 6. The water budget method should not be used to determine or adjust the official storage change estimate calculated using the new three-layer method. It can be used to calculate preliminary storage change estimates (using assumed incidental recharge) prior to performing the annual three-layer storage calculation. However, the annual storage change and accumulated overdraft official record for that year should be the exact value from the three-layer storage method steps above. This will prevent an accumulation of unknown discrepancy when rectifying back to previous years. 6. BASIN OPERATING RANGE AND STRATEGY The level of accumulated overdraft in the basin, both for the current and upcoming year, affects important basin management decisions, including determining imported water needs and setting the Basin Pumping Percentage (BPP), both of which have major financial effects on the District and groundwater producers. Therefore, it is crucial to have an operational strategy to ensure that the basin is managed within acceptable overdraft limits to prevent detrimental impacts to the basin while also striving to maximize water reliability and financial efficiency. In the discussion that follows, all storage and overdraft conditions are defined for June 30 of a given year, which is the ending date of the water year (July 1 through June 30) and thus the date represented by the June annual contour maps used for the storage change calculation. Seasonal fluctuations in water levels and basin storage occur throughout the water year and are tracked for reporting purposes, and are used, along with the end-of-year accumulated overdraft, in making management decisions. ---PAGE BREAK--- 39 6.1 Basin Operating Range and Optimal Target The operating range of the basin is considered to be the maximum allowable storage range without incurring detrimental impacts. The upper limit of the operating range is defined by the new full basin condition, which represents the zero-overdraft benchmark. Although it may be physically possible to fill the basin higher than this full condition, it could lead to detrimental impacts such as percolation reductions in recharge facilities and increased risk of shallow groundwater seepage in low-lying coastal areas. The lower limit of the operating range is considered to be 500,000 af overdraft and represents the lowest acceptable level in the basin, not the lowest achievable. This level also assumes that all MWD water stored in the basin Conjuctive Use Storage Project and Super In-Lieu) has already been withdrawn. Although it is considered to be generally acceptable to allow the basin to decline to 500,000 af overdraft for brief periods due to severe drought conditions and lack of supplemental imported water supplies, it is not considered to be an acceptable management practice to intentionally manage the basin for sustained periods at this lower limit for the following reasons: • Seawater intrusion likely • Drought supply depleted • Pumping levels detrimental to a handful of wells • Increased pumping lifts and electrical costs • Increased potential for color upwelling from the Deep aquifer Of course, detrimental impacts like those listed above do not suddenly happen when the overdraft gets down to exactly 500,000 af; rather, they occur incrementally, or the potential for their occurrence grows as the basin declines to lower levels. However, basin model computer simulations indicate that many of these detrimental impacts become evident at an overdraft of approximately 500,000 af. For example, at 500,000 af overdraft, model-simulated water levels in the Talbert Gap area were marginally low and not protective of seawater intrusion, even with the increased injection from GWRS Phase 1. Furthermore, worst case basin model runs at 700,000 af overdraft indicated seawater intrusion becoming even worse and considerably more production wells being impacted by low pumping levels. Thus, an accumulated overdraft level of 700,000 af did not appear to be acceptable, not even for short durations. At overdraft levels significantly below 500,000 af overdraft, the potential for land subsidence could also become an issue. Based on historical hydrology and recharge water availability, an accumulated overdraft of 100,000 af best represents an optimal basin management target. This optimal target level provides sufficient storage space to accommodate anticipated recharge from a single wet year while also providing water in storage for at least 2 or 3 consecutive years of drought. ---PAGE BREAK--- 40 Table 6-1 shows that basin storage could increase by as much as 100,000 af in a somewhat typical wet year based on predicted increased supplies. The Captured Santa Ana River Flows and Natural Incidental Recharge terms were both based on an average of four historical wet years: 1992-93, 1994-95, 1997-98, and 2004-05. Based on historical rainfall records for the Orange County area, wet years typically do not occur back-to-back. Therefore, the optimal overdraft target of 100,000 af provides the storage capacity to capture the increased supplies from this one typically wet year. Table 6-1. Anticipated Supply Increases for a Typical Wet Year Table 6-2 shows that basin storage could decrease by approximately 90,000 af in a dry year based on reduced supplies. However, unlike wet years, historical rainfall records for this area show that dry years often occur for 2 or 3 consecutive years. Therefore, the 90,000 af of reduced supplies in a dry year could result in a 270,000 af decrease in basin storage after 3 consecutive years of drought. Assuming the basin to be at the optimal target of 100,000 af going into a three-year drought, the accumulated overdraft at the end of the drought would be 370,000 af, which is still within the acceptable operating range. Table 6-2. Anticipated Supply Reductions for Typical Dry Years 20,000 Reduced Demand (Pumping) 100,000 Potential Storage Increase 30,000 Natural Incidental Recharge * 50,000 Captured Santa Ana River Flows * 1 Year (AF) Increased Supplies (Above Average Annual Amounts) * Average of four wet years: 92-93, 94-95, 97-98, 04-05 Assumes no mid-year BPP change -90,000 -20,000 -40,000 -30,000 1 Year (AF) -270,000 -60,000 -120,000 -90,000 3 Years (AF) Total Potential Storage Change* Natural Incidental Recharge Santa Ana River Flows MWD Replenishment Water Reduced Supplies (From Average Annual Amounts) * Assumes no mid-year BPP change ---PAGE BREAK--- 41 Figure 6-1 schematically illustrates the various overdraft levels discussed above in relation to one another; namely, the new full benchmark, the optimal overdraft target of 100,000 af, and the lower limit of the operating range at 500,000 af accumulated overdraft. Figure 6-1. Strategic Basin Operating Levels and Optimal Target 6.2 Basin Management Operational Strategy The primary “tool” for managing the basin is the Basin Production Percentage (BPP). Each year in April, the District’s Board of Directors sets the BPP for the upcoming water year. In addition to purchasing replenishment water, adjusting the BPP allows the District to effectively increase or decrease basin storage. Figure 6-2 shows the formula used to calculate the BPP each year. Only the two terms highlighted in blue and red in the BPP formula are adjustable at the District’s discretion, namely the planned amount of recharge (including replenishment water purchases) and the planned amount of basin refill or storage decrease for the coming year. The amount of recharge planned and budgeted for the coming year may be limited by factors outside the District’s control, such as the availability of imported water for either direct replenishment or In-Lieu. For example, following statewide wet years, MWD may - 418,000 AF Provides at least 3 years of drought supply above MWD storage 82,000 af MWD storage * 66,000 AF CUP Storage 16,000 AF Super In-Lieu - 500,000 AF 0 AF - 100,000 AF Available storage for one wet year OCWD Operating Range OPTIMAL TARGET Lowest Acceptable Level New Full Condition * Current maximum approved volume ---PAGE BREAK--- 42 offer incentives (financial or otherwise) for local water agencies to take additional amounts of surplus imported water, whereas during a long-term statewide drought the surplus imported water may simply not be available. Figure 6-2. BPP Formula The planned amount of basin refill or storage decrease for the coming year is within the District’s control but is also considered within the context of financial impacts to both the District and the groundwater producers. Therefore, unless the basin is near the bottom of the acceptable operating range or close to being full, a moderate amount of basin refill or decrease would typically be proposed that aims to move toward the optimal overdraft target. If the basin is already at or near the 100,000 af overdraft target, then a neutral stance can be taken that attempts to balance basin production and recharge with no planned storage change. Figure 6-3 schematically illustrates the generalized basin refill or storage decrease strategy based on the accumulated overdraft. When the basin is higher than the optimal overdraft target and nearly full, the amount of planned storage decrease of up to 50,000 af for the coming year may be recommended. This may be accomplished by a combination of raising the BPP and reducing replenishment purchases. The proposed operational strategy illustrated in Figure 6-3 provides a flexible guideline to assist in determining the amount of basin refill or storage decrease for the coming water year based on using the BPP formula and considering storage goals based on current basin conditions and other factors such as water availability. This strategy is not intended to dictate a specific basin refill or storage decrease amount for a given storage condition but to provide a general guideline for the District’s Board of Directors. Last Calendar Year’s Total Water Demand Water Recharged Basin Refill or Decrease Water Quality Improvement Projects (Pumping Above BPP) Reclaimed & Local Supplies BPP = ---PAGE BREAK--- 43 Figure 6-3. Basin Management Operational Strategy 7. FINDINGS Findings of this study are enumerated below. 1. The new three-layer storage change approach is technically feasible and provides a more accurate assessment than the traditional single-layer storage change method. 2. Using the new three-layer method, the majority of the storage change occurs in the Forebay area of the basin within the unconfined Shallow aquifer where rising or falling of the water table fills or drains empty pore space. 3. Accuracy of the storage change and accumulated overdraft estimates is dependent upon good spatial distribution of water level measurements as well as the storage coefficient values used in the calculations. Water level data for the Shallow aquifer were relatively sparse in outlying Forebay areas of the basin, leading to some uncertainty in preparing groundwater elevation contours in those areas. - 418,000 AF 82,000 af MWD storage - 500,000 AF 0 AF - 100,000 AF Reduce up to 50,000 AFY - 150,000 AF “Neutral” More active management of basin in conjunction with availability of imported water and basin condition Use BPP Formula OPTIMAL TARGET ---PAGE BREAK--- 44 4. 1969 no longer represents a truly full-basin benchmark. A new full-basin water level condition was developed based on the following prescribed conditions: • Observed historical high water levels • Present-day pumping and recharge conditions • Protective of seawater intrusion • Minimal potential for mounding at or near recharge basins The new full-basin water levels in the Forebay area are essentially at or very near the bottom of the District’s deep percolation basins Anaheim Lake). Historical water level data from 1994 have shown that this condition is achievable without detrimental effects. Water levels higher than this new full condition may be physically achievable in the Forebay area but not recommended due to the likelihood of groundwater mounding and reduced percolation in recharge basins. 5. Using the new three-layer storage change calculation in conjunction with the new full benchmark and June 2006 water levels, an accumulated overdraft of 135,000 af was calculated representing June 30, 2006. Similarly, using the new three-layer method to compare the new full water levels to those of June 2005, an accumulated overdraft of 201,000 af was calculated representing June 30, 2005. Subtracting the June 2006 accumulated overdraft from that of June 2005 yielded an annual storage increase of 66,000 af for WY 2005-06. 6. Comparing the current year’s water level conditions to the full basin benchmark each successive year for calculating the basin storage will eliminate the potential for cumulative discrepancies over several years. 7. An accumulated overdraft of 500,000 af represents the lowest acceptable limit of the basin’s operating range. This lower limit of 500,000 af assumes that stored MWD water (CUP and Super In-Lieu) has already been removed and is only acceptable for short durations due to drought conditions. It is not recommended to manage the basin for sustained periods at this lower limit for the following reasons: • Seawater intrusion likely • Drought supply depleted • Pumping levels detrimental to a handful of wells • Increased pumping lifts and electrical costs • Increased potential for color upwelling from the Deep aquifer 8. An optimal basin management target of 100,000 af of accumulated overdraft provides sufficient storage space to accommodate increased supplies from one wet year while also providing enough water in storage to offset decreased supplies during a two- to three-year drought. ---PAGE BREAK--- 45 9. The proposed operational strategy provides a flexible guideline to assist in determining the amount of basin refill or storage decrease for the coming water year based on using the BPP formula and considering storage goals based on current basin conditions and other factors such as water availability. This strategy is not intended to dictate a specific basin refill or storage decrease amount for a given storage condition but to provide a general guideline for the District’s Board of Directors. 8. RECOMMENDATIONS Based on the findings of this study are the following recommendations: 1. Adopt the new three-layer storage change methodology along with the associated new full-basin condition that will serve as a benchmark for calculating the basin accumulated overdraft. 2. Adopt the proposed basin operating strategy including a basin operating range spanning the new full condition to an accumulated overdraft of 500,000 af, and an optimal overdraft target of 100,000 af. 3. Include in the 2007-08 CIP budget the installation of six Shallow aquifer monitoring wells to increase accuracy of the three-layer storage change calculation. 9. BIBLIOGRAPHY Bear, J. 1979. Hydraulics of Groundwater. McGraw-Hill, New York, 569 pp. Bouwer, H. 1978. Groundwater Hydrology. McGraw-Hill, New York, 480 pp. California State Department of Water Resources. 1934. “Geology and Ground Water Storage Capacity of Valley Fill.” Bulletin No. 45. California State Department of Public Works, Division of Water Resources. June, 1945. “Present Overdraft on and Safe Yield from The Groundwater of the Coastal Plain of Orange County.” Freeze, R. and J. A. Cherry. 1979. Groundwater. Prentice-Hall, Englewood Cliffs, New Jersey, 604 pp. Phraner, R. B. Harley, E. G. Reichard, and B. Stollar. 2001. Letter from OCWD Basin Model Advisory Panel to OCWD: “Findings of Model Advisory Panel – Transient Calibration of Multi-layer Basin Flow Model,” 7pp. ---PAGE BREAK--- APPENDIX 1 “Randall” Specific Yield Values From Traditional Storage Change Method ---PAGE BREAK--- ---PAGE BREAK--- APPENDIX 2 Basin Model Storage Coefficient Values For Three-Layer Storage Change Method ---PAGE BREAK--- Shallow Aquifer Storage Coefficients Unconfined Conditions Basin Model Layer 1 These values only get used where the Shallow aquifer is unconfined, primarily in the Forebay area. ---PAGE BREAK--- Shallow Aquifer Storage Coefficients Confined Conditions Basin Model Layer 1 These values only get used where the Shallow aquifer is confined (within the Pressure Area). ---PAGE BREAK--- Principal Aquifer Storage Coefficients Confined Conditions Basin Model Layer 2 These values get used wherever the Principal aquifer is confined, which is typically the entire Layer 2 area. ---PAGE BREAK--- Principal Aquifer Storage Coefficients Unconfined Conditions Basin Model Layer 2 These values only get used where the Principal aquifer goes unconfined, typically only the Santiago area under low-basin conditions ---PAGE BREAK--- Basin Model Layer 3 Deep Aquifer Storage Coefficients Confined Conditions These values get used wherever the Deep aquifer is confined, which is the entire Layer 3 area. ---PAGE BREAK--- Deep Aquifer Storage Coefficients Unconfined Conditions Basin Model Layer 3 These values only get used if the Deep aquifer goes unconfined in some fringe area, which should never happen. ---PAGE BREAK--- APPENDIX 3 Water Level Change Maps For June 2006 to the New Full Condition ---PAGE BREAK--- Shallow Aquifer Water Level Change From June 2006 to Full ---PAGE BREAK--- Principal Aquifer Water Level Change From June 2006 to Full ---PAGE BREAK--- Deep Aquifer Water Level Change From June 2006 to Full ---PAGE BREAK--- APPENDIX E OCWD MONITORING WELLS ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) ABS-2 SINGLE CASING 1 175 155 165 AM-1 SINGLE CASING 1 137 97 115 AM-2 SINGLE CASING 1 156 87 100 AM-3 SINGLE CASING 1 112 91 107 AM-4 SINGLE CASING 1 296 187 205 AM-5 SINGLE CASING 1 247 230 245 AM-5A SINGLE CASING 1 180 168 175 AM-6 SINGLE CASING 1 296 232 250 AM-7 SINGLE CASING 1 297 210 225 AM-8 SINGLE CASING 1 297 268 285 AM-9 SINGLE CASING 1 317 285 303 AM-10 SINGLE CASING 1 298 217 235 AM-11 SINGLE CASING 1 276 218 240 AM-12 SINGLE CASING 1 294 210 225 AM-13 SINGLE CASING 1 275 252 270 AM-14 SINGLE CASING 1 317 297 315 AM-15 SINGLE CASING 1 318 300 317 AM-15A SINGLE CASING 1 231 214 220 AM-16 SINGLE CASING 1 320 300 315 AM-16A SINGLE CASING 1 227 215 222 AM-17 SINGLE CASING 1 318 290 308 AM-18 SINGLE CASING 1 316 291 309 AM-18A SINGLE CASING 1 234 208 215 AM-19 SINGLE CASING 1 237 217 225 AM-19A SINGLE CASING 1 126 115 123 AM-20 SINGLE CASING 1 397 361 379 AM-20A SINGLE CASING 1 268 250 258 AM-21 SINGLE CASING 1 269 250 258 AM-21A SINGLE CASING 1 179 157 165 AM-22 SINGLE CASING 1 356 339 353 AM-22A SINGLE CASING 1 239 216 224 AM-23 SINGLE CASING 1 351 330 347 AM-24 SINGLE CASING 1 378 335 350 AM-24A SINGLE CASING 1 306 279 294 AM-25 SINGLE CASING 1 362 340 358 AM-25A SINGLE CASING 1 219 188 195 AM-26 SINGLE CASING 1 388 377 383 AM-27 SINGLE CASING 1 336 287 305 AM-28 SINGLE CASING 1 398 358 376 AM-29 SINGLE CASING 1 367 340 358 AM-29A SINGLE CASING 1 95 75 95 AM-30 SINGLE CASING 1 375 349 367 AM-30A SINGLE CASING 1 398 152 159 AM-31 SINGLE CASING 1 358 335 353 AM-31A SINGLE CASING 1 360 162 170 AM-32 SINGLE CASING 1 398 335 353 AM-33 SINGLE CASING 1 378 354 372 AM-33A SINGLE CASING 1 238 206 221 AM-34 SINGLE CASING 1 354 317 335 AM-34A SINGLE CASING 1 271 252 260 AM-35 SINGLE CASING 1 400 332 350 NA: Not Available 1 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) AM-36 SINGLE CASING 1 398 369 387 AM-37 SINGLE CASING 1 378 349 367 AM-38 SINGLE CASING 1 358 316 334 AM-39 SINGLE CASING 1 188 168 188 AM-39A SINGLE CASING 1 135 115 135 AM-40 SINGLE CASING 1 191 175 190 AM-40A SINGLE CASING 1 166 145 165 AM-41 SINGLE CASING 1 200 190 200 AM-41A SINGLE CASING 1 166 156 166 AM-42 SINGLE CASING 1 190 180 190 AM-42A SINGLE CASING 1 130 115 130 AM-43 SINGLE CASING 1 100 80 100 AM-44 SINGLE CASING 1 160 140 160 AM-44A SINGLE CASING 1 88 78 88 AM-45 SINGLE CASING 1 132 102 132 AM-46 SINGLE CASING 1 124 94 124 AM-47 SINGLE CASING 1 247 227 242 AM-47A SINGLE CASING 1 170 160 170 AM-48 SINGLE CASING 1 305 270 300 AM-48A SINGLE CASING 1 151 116 146 AM-49 SINGLE CASING 1 155 120 150 AMD-9 NESTED 1 230 200 220 AMD-9 NESTED 2 480 450 470 AMD-9 NESTED 3 610 580 600 AMD-9 NESTED 4 926 896 916 AMD-10 NESTED 1 322 292 312 AMD-10 NESTED 2 470 440 460 AMD-10 NESTED 3 580 550 570 AMD-10 NESTED 4 804 774 794 AMD-10 NESTED 5 964 934 954 AMD-11 NESTED 1 328 298 318 AMD-11 NESTED 2 426 396 416 AMD-11 NESTED 3 630 600 620 AMD-11 NESTED 4 716 686 706 AMD-11 NESTED 5 936 906 926 AMD-12 NESTED 1 360 330 350 AMD-12 NESTED 2 530 490 520 AMD-12 NESTED 3 625 595 615 AMD-12 NESTED 4 755 725 745 AMD-12 NESTED 5 970 940 960 FM-1 SINGLE CASING 1 359 348 356 FM-1A SINGLE CASING 1 197 164 172 FM-2 SINGLE CASING 1 352 320 338 FM-2A SINGLE CASING 1 237 226 234 FM-3 SINGLE CASING 1 298 257 263 FM-4 SINGLE CASING 1 355 327 345 FM-4A SINGLE CASING 1 170 142 160 FM-5 SINGLE CASING 1 141 121 141 FM-6 SINGLE CASING 1 320 150 310 FM-7 SINGLE CASING 1 197 187 197 FM-7A SINGLE CASING 1 170 160 170 NA: Not Available 2 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) FM-8 SINGLE CASING 1 139 114 134 FM-9 SINGLE CASING 1 245 220 240 FM-9A SINGLE CASING 1 191 166 186 FM-10 SINGLE CASING 1 240 215 235 FM-10A SINGLE CASING 1 176 151 171 FM-11 SINGLE CASING 1 261 236 256 FM-11A SINGLE CASING 1 159 134 154 FM-12 SINGLE CASING 1 231 206 226 FM-12A SINGLE CASING 1 160 135 155 FM-13 SINGLE CASING 1 235 210 230 FM-13A SINGLE CASING 1 165 140 160 FM-14 SINGLE CASING 1 259 234 254 FM-14A SINGLE CASING 1 172 147 167 FM-15 SINGLE CASING 1 243 218 238 FM-15A SINGLE CASING 1 145 120 140 FM-16 SINGLE CASING 1 273 248 268 FM-16A SINGLE CASING 1 150 125 145 FM-17 SINGLE CASING 1 275 250 270 FM-18 SINGLE CASING 1 254 224 244 FM-18A SINGLE CASING 1 156 121 151 FM-19A SINGLE CASING 1 140 115 135 FM-19B SINGLE CASING 1 265 230 260 FM-19C SINGLE CASING 1 390 365 385 FM-20 SINGLE CASING 1 246 221 241 FM-20A SINGLE CASING 1 155 130 150 FM-21 SINGLE CASING 1 275 260 270 FM-21A SINGLE CASING 1 165 140 160 FM-22 SINGLE CASING 1 267 242 265 FM-22A SINGLE CASING 1 175 150 170 FM-23 SINGLE CASING 1 253 234 249 FM-23A SINGLE CASING 1 149 128 143 FM-24 SINGLE CASING 1 295 271 291 FM-24A SINGLE CASING 1 184 154 174 FM-25 SINGLE CASING 1 152 132 152 FM-26 SINGLE CASING 1 155 145 155 FM-27 SINGLE CASING 1 125 105 125 IDM-3 NESTED 1 214 174 194 IDM-3 NESTED 2 330 290 310 IDM-3 NESTED 3 682 652 672 IDM-4 NESTED 1 166 136 156 IDM-4 NESTED 2 302 272 292 IDM-4 NESTED 3 684 654 674 IDP-2R NESTED 1 205 155 195 IDP-2R NESTED 2 350 300 340 IDP-3 SINGLE CASING 1 525 125 505 IDP-4 SINGLE CASING 1 430 125 410 KBS-1 SINGLE CASING 1 230 209 219 KBS-3 SINGLE CASING 1 90 80 90 KBS-4 SINGLE CASING 1 158 138 158 KBS-4A SINGLE CASING 1 90 80 90 MCAS-4 SINGLE CASING 1 275 181 238 NA: Not Available 3 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) MCAS-5A SINGLE CASING 1 133 120 130 MCAS-6 SINGLE CASING 1 285 167 222 MCAS-8 SINGLE CASING 1 435 392 410 MCAS-9 SINGLE CASING 1 450 372 445 MCAS-10 SINGLE CASING 1 389 347 377 MSP-10P SINGLE CASING 1 50 40 50 MSP-10T SINGLE CASING 1 140 70 140 OCWD-7 SINGLE CASING 1 48 28 48 OCWD-33Z11 NESTED 1 384 338 379 OCWD-33Z11 NESTED 2 490 435 485 OCWD-34F10 NESTED 1 231 215 225 OCWD-34F10 NESTED 2 291 270 285 OCWD-34F10 NESTED 3 346 315 340 OCWD-34F10 NESTED 4 465 420 460 OCWD-34H25 NESTED 1 356 300 350 OCWD-34H25 NESTED 2 470 410 465 OCWD-34H5 NESTED 1 360 300 340 OCWD-34H5 NESTED 2 475 405 455 OCWD-34L10 NESTED 1 191 165 185 OCWD-34L10 NESTED 2 266 225 260 OCWD-34L10 NESTED 3 371 311 365 OCWD-34L10 NESTED 4 455 405 450 OCWD-34N21 NESTED 1 NA 329 366 OCWD-34N21 NESTED 2 NA 424 464 OCWD-34U8 NESTED 1 180 149 174 OCWD-34U8 NESTED 2 240 224 234 OCWD-34U8 NESTED 3 325 279 319 OCWD-34U8 NESTED 4 389 359 384 OCWD-34V20 NESTED 1 313 235 307 OCWD-34V20 NESTED 2 422 387 417 OCWD-35F20 NESTED 1 NA 70 95 OCWD-35F20 NESTED 2 NA 115 125 OCWD-35F20 NESTED 3 NA 145 180 OCWD-35F20 NESTED 4 NA 235 265 OCWD-35H11 NESTED 1 225 200 220 OCWD-35H11 NESTED 2 163 125 158 OCWD-35H11 NESTED 3 82 44 77 OCWD-35H12 SINGLE CASING 1 159 137 147 OCWD-35J1 NESTED 1 260 190 240 OCWD-35J1 NESTED 2 190 130 170 OCWD-35K1 NESTED 1 263 193 243 OCWD-35K1 NESTED 2 190 130 170 OCWD-35N01 NESTED 1 90 80 85 OCWD-35N01 NESTED 2 80 39 79 OCWD-35T9 SINGLE CASING 1 432 390 411 OCWD-36FP1Z SINGLE CASING 1 NA 504 514 OCWD-36FP14Z1 SINGLE CASING 1 135 115 125 OCWD-AIR1 NESTED 1 255 200 250 OCWD-AIR1 NESTED 2 515 410 510 OCWD-AIR1 NESTED 3 855 675 850 OCWD-AIR1 NESTED 4 1485 1375 1460 NA: Not Available 4 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) OCWD-AN1 SINGLE CASING 1 115 35 115 OCWD-AN2 SINGLE CASING 1 115 35 115 OCWD-BP1 SINGLE CASING 1 40 20 40 OCWD-BP2 SINGLE CASING 1 70 50 70 OCWD-BP3 SINGLE CASING 1 205 185 205 OCWD-BP4 SINGLE CASING 1 180 140 180 OCWD-BP5 NESTED 1 75 55 75 OCWD-BP5 NESTED 2 167 147 167 OCWD-BP6 SINGLE CASING 1 168 148 168 OCWD-BP7 NESTED 1 57 47 57 OCWD-BP7 NESTED 2 168 148 168 OCWD-BS15 SINGLE CASING 1 75 60 70 OCWD-BS16 SINGLE CASING 1 85 60 80 OCWD-BS18 SINGLE CASING 1 87 72 82 OCWD-BS19 SINGLE CASING 1 88 63 83 OCWD-CTG1 NESTED 1 265 160 260 OCWD-CTG1 NESTED 2 725 420 720 OCWD-CTG1 NESTED 3 1025 800 1025 OCWD-CTG1 NESTED 4 1225 1060 1220 OCWD-CTG5 NESTED 1 620 420 620 OCWD-CTG5 NESTED 2 1000 880 1000 OCWD-CTG5 NESTED 3 1120 1040 1120 OCWD-CTK1 NESTED 1 660 410 655 OCWD-CTK1 NESTED 2 1020 780 1015 OCWD-CTK1 NESTED 3 1320 1260 1315 OCWD-FBM1 SINGLE CASING 1 140 38 138 OCWD-FBM2 SINGLE CASING 1 140 39 139 OCWD-FC1 SINGLE CASING 1 185 165 185 OCWD-FC2 SINGLE CASING 1 115 95 115 OCWD-FH1 SINGLE CASING 1 140 120 140 OCWD-GA1 SINGLE CASING 1 40 30 40 OCWD-GA2 SINGLE CASING 1 40 30 40 OCWD-GA3 SINGLE CASING 1 40 30 40 OCWD-GA4 SINGLE CASING 1 40 30 40 OCWD-GA5 SINGLE CASING 1 40 30 40 OCWD-GA6 SINGLE CASING 1 40 30 40 OCWD-GA7 SINGLE CASING 1 40 30 40 OCWD-GA9 SINGLE CASING 1 29 19 29 OCWD-I27M1 SINGLE CASING 1 22 17 22 OCWD-I28M1 SINGLE CASING 1 24 19 24 OCWD-KB1 SINGLE CASING 1 200 180 200 OCWD-KR2 SINGLE CASING 1 394 NA NA OCWD-LB1 NESTED 1 35 25 35 OCWD-LB1 NESTED 2 168 148 168 OCWD-LB2 SINGLE CASING 1 30 15 30 OCWD-LB3 NESTED 1 46 36 46 OCWD-LB3 NESTED 2 165 145 165 OCWD-LV1 SINGLE CASING 1 155 135 155 OCWD-M1 SINGLE CASING 1 115 75 110 OCWD-M2 SINGLE CASING 1 155 85 150 OCWD-M4 NESTED 1 125 80 120 NA: Not Available 5 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) OCWD-M4 NESTED 2 180 145 175 OCWD-M4 NESTED 3 275 235 270 OCWD-M4 NESTED 4 335 295 330 OCWD-M5 NESTED 1 100 65 95 OCWD-M5 NESTED 2 165 115 160 OCWD-M5 NESTED 3 265 215 260 OCWD-M5 NESTED 4 310 285 305 OCWD-M6A NESTED 1 130 65 125 OCWD-M6A NESTED 2 170 150 165 OCWD-M6A NESTED 3 290 260 285 OCWD-M6B SINGLE CASING 1 240 185 235 OCWD-M7A NESTED 1 140 70 135 OCWD-M7A NESTED 2 175 155 170 OCWD-M7A NESTED 3 225 190 220 OCWD-M7B SINGLE CASING 1 265 240 260 OCWD-M8 NESTED 1 155 50 150 OCWD-M8 NESTED 2 210 185 205 OCWD-M8 NESTED 3 255 225 250 OCWD-M8 NESTED 4 315 275 310 OCWD-M9 NESTED 1 120 90 115 OCWD-M9 NESTED 2 160 135 155 OCWD-M9 NESTED 3 230 185 225 OCWD-M9 NESTED 4 300 250 295 OCWD-M10 NESTED 1 165 80 160 OCWD-M10 NESTED 2 200 175 195 OCWD-M10 NESTED 3 245 215 240 OCWD-M10 NESTED 4 310 280 305 OCWD-M11 NESTED 1 110 70 105 OCWD-M11 NESTED 2 155 125 150 OCWD-M11 NESTED 3 230 170 225 OCWD-M11 NESTED 4 295 260 290 OCWD-M12 NESTED 1 115 70 110 OCWD-M12 NESTED 2 225 130 220 OCWD-M12 NESTED 3 265 240 260 OCWD-M12 NESTED 4 355 330 350 OCWD-M13 NESTED 1 100 65 95 OCWD-M13 NESTED 2 205 140 200 OCWD-M13 NESTED 3 300 230 295 OCWD-M13 NESTED 4 400 360 395 OCWD-M14A NESTED 1 95 60 90 OCWD-M14A NESTED 2 185 120 180 OCWD-M14A NESTED 3 305 200 300 OCWD-M14B SINGLE CASING 1 345 320 340 OCWD-M15A NESTED 1 90 60 85 OCWD-M15A NESTED 2 180 115 175 OCWD-M15A NESTED 3 295 195 290 OCWD-M15B SINGLE CASING 1 340 310 335 OCWD-M16 NESTED 1 95 65 90 OCWD-M16 NESTED 2 165 115 160 OCWD-M16 NESTED 3 275 180 270 OCWD-M16 NESTED 4 320 295 315 NA: Not Available 6 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) OCWD-M17A NESTED 1 100 60 95 OCWD-M17A NESTED 2 190 130 185 OCWD-M17A NESTED 3 350 330 345 OCWD-M17B SINGLE CASING 1 310 210 305 OCWD-M18 NESTED 1 95 65 90 OCWD-M18 NESTED 2 180 110 175 OCWD-M18 NESTED 3 295 195 290 OCWD-M18 NESTED 4 340 310 335 OCWD-M19 NESTED 1 115 60 110 OCWD-M19 NESTED 2 200 130 195 OCWD-M19 NESTED 3 270 215 265 OCWD-M20 NESTED 1 110 60 105 OCWD-M20 NESTED 2 200 170 195 OCWD-M20 NESTED 3 275 255 270 OCWD-M21 NESTED 1 105 65 100 OCWD-M21 NESTED 2 190 150 185 OCWD-M21 NESTED 3 265 205 260 OCWD-M21 NESTED 4 345 320 340 OCWD-M22 NESTED 1 110 70 105 OCWD-M22 NESTED 2 215 140 210 OCWD-M22 NESTED 3 275 230 270 OCWD-M23A NESTED 1 95 65 90 OCWD-M23A NESTED 2 170 110 165 OCWD-M23A NESTED 3 265 190 260 OCWD-M23B SINGLE CASING 1 325 295 320 OCWD-M24 NESTED 1 100 70 95 OCWD-M24 NESTED 2 170 115 165 OCWD-M24 NESTED 3 235 185 230 OCWD-M24 NESTED 4 315 290 310 OCWD-M25 SINGLE CASING 1 195 65 185 OCWD-M26 SINGLE CASING 1 145 70 135 OCWD-M27 SINGLE CASING 1 120 60 110 OCWD-M28 SINGLE CASING 1 155 80 145 OCWD-M30 SINGLE CASING 1 120 90 110 OCWD-M31 SINGLE CASING 1 172 82 162 OCWD-M36 NESTED 1 95 80 90 OCWD-M36 NESTED 2 180 165 175 OCWD-M36 NESTED 3 255 240 250 OCWD-M36 NESTED 4 305 290 300 OCWD-M37 NESTED 1 135 120 130 OCWD-M37 NESTED 2 195 180 190 OCWD-M37 NESTED 3 245 230 240 OCWD-M37 NESTED 4 312 297 307 OCWD-M37 NESTED 5 353 338 348 OCWD-M38 NESTED 1 114 94 104 OCWD-M38 NESTED 2 176 156 166 OCWD-M38 NESTED 3 254 234 244 OCWD-M38 NESTED 4 356 336 346 OCWD-M38 NESTED 5 536 516 526 OCWD-M39 NESTED 1 90 70 80 OCWD-M39 NESTED 2 130 100 120 NA: Not Available 7 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) OCWD-M39 NESTED 3 180 150 170 OCWD-M39 NESTED 4 220 200 210 OCWD-M39 NESTED 5 280 250 270 OCWD-M40 NESTED 1 115 85 105 OCWD-M40 NESTED 2 190 160 180 OCWD-M40 NESTED 3 235 205 225 OCWD-M40 NESTED 4 530 330 520 OCWD-M41 NESTED 1 86 66 76 OCWD-M41 NESTED 2 115 95 105 OCWD-M41 NESTED 3 220 200 210 OCWD-M41 NESTED 4 256 236 246 OCWD-M41 NESTED 5 400 370 390 OCWD-M42 NESTED 1 130 100 120 OCWD-M42 NESTED 2 157 137 147 OCWD-M42 NESTED 3 230 210 220 OCWD-M42 NESTED 4 290 260 280 OCWD-M42 NESTED 5 530 500 520 OCWD-M42 NESTED 6 638 608 628 OCWD-M43 NESTED 1 156 136 146 OCWD-M43 NESTED 2 320 290 310 OCWD-M43 NESTED 3 360 340 350 OCWD-M43 NESTED 4 410 380 400 OCWD-M43 NESTED 5 550 520 540 OCWD-M44 NESTED 1 65 50 60 OCWD-M44 NESTED 2 125 100 120 OCWD-M44 NESTED 3 155 140 150 OCWD-M44 NESTED 4 280 245 275 OCWD-M44 NESTED 5 310 295 305 OCWD-M44A SINGLE CASING 1 125 100 125 OCWD-M44 NESTED 1 65 50 60 OCWD-M44 NESTED 2 125 100 120 OCWD-M44 NESTED 3 155 140 150 OCWD-M44 NESTED 4 280 245 275 OCWD-M44 NESTED 5 310 295 305 OCWD-M45 NESTED 1 215 195 205 OCWD-M45 NESTED 2 270 250 260 OCWD-M45 NESTED 3 355 335 345 OCWD-M45 NESTED 4 400 380 390 OCWD-M45 NESTED 5 800 780 790 OCWD-M46 NESTED 1 380 350 370 OCWD-M46 NESTED 2 440 420 430 OCWD-M46 NESTED 3 545 515 535 OCWD-M46 NESTED 4 670 640 660 OCWD-M46 NESTED 5 920 890 910 OCWD-M46A SINGLE CASING 1 380 350 370 OCWD-M46 NESTED 1 380 350 370 OCWD-M46 NESTED 2 440 420 430 OCWD-M46 NESTED 3 545 515 535 OCWD-M46 NESTED 4 670 640 660 OCWD-M46 NESTED 5 920 890 910 OCWD-M47 NESTED 1 385 355 375 NA: Not Available 8 of 9 ---PAGE BREAK--- APPENDIX E - OCWD ACTIVE GROUNDWATER MONITORING WELLS (Excluding Westbay Multiport Wells) Well Name Well Type Casing Sequence No. Cased Depth (ft.) Top Perforation (ft.) Bottom Perforation (ft.) OCWD-M47 NESTED 2 490 470 480 OCWD-M47 NESTED 3 610 580 600 OCWD-M47 NESTED 4 775 745 765 OCWD-M47 NESTED 5 970 940 960 OCWD-M48 NESTED 1 110 80 100 OCWD-M48 NESTED 2 205 175 195 OCWD-M48 NESTED 3 490 470 480 OCWD-MOOR SINGLE CASING 1 470 NA NA OCWD-RVW1 SINGLE CASING 1 78 67 77 OCWD-RVW1A SINGLE CASING 1 49 39 49 OCWD-T2 NESTED 1 33 20 30 OCWD-T2 NESTED 2 180 70 170 OCWD-T2 NESTED 3 370 300 360 OCWD-T3 NESTED 1 95 65 85 OCWD-T3 NESTED 2 180 110 170 OCWD-T4 SINGLE CASING 1 176 68 168 OCWD-T5 NESTED 1 200 110 190 OCWD-T5 NESTED 2 305 285 295 OCWD-W1 SINGLE CASING 1 398 NA NA OCWD-YLR1 SINGLE CASING 1 40 35 40 OCWD-YLR2 SINGLE CASING 1 37 32 37 OCWD-YLR3 SINGLE CASING 1 36 31 36 OM-1 SINGLE CASING 1 245 217 235 OM-2 SINGLE CASING 1 250 211 219 OM-2A SINGLE CASING 1 130 118 125 OM-4 SINGLE CASING 1 237 221 230 OM-4A SINGLE CASING 1 119 112 117 OM-6 SINGLE CASING 1 249 196 204 OM-8 SINGLE CASING 1 319 285 293 OM-8A SINGLE CASING 1 178 156 164 SCS-3 SINGLE CASING 1 42 31 42 SCS-4 SINGLE CASING 1 32 21 32 SCS-5 SINGLE CASING 1 43 22 43 SCS-6 NESTED 1 29 23 29 SCS-6 NESTED 2 153 147 153 SCS-7 NESTED 1 36 20 36 SCS-7 NESTED 2 141 125 141 SCS-8 SINGLE CASING 1 129 108 129 SCS-9 SINGLE CASING 1 178 153 173 SCS-10 SINGLE CASING 1 221 206 216 SCS-B1 NESTED 1 43 18 43 SCS-B2 NESTED 1 10 5 10 SCS-B2 NESTED 2 29 19 29 SCS-B3 NESTED 1 10 5 10 SCS-B3 NESTED 2 25 16 26 TIC-67 SINGLE CASING 1 902 245 900 W-14659 SINGLE CASING 1 27 12 27 W-15061 SINGLE CASING 1 NA NA NA NA: Not Available 9 of 9 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) ABS-1/1/WB1/MP1 WESTBAY MULTIPORT 1 27 25 35 ABS-1/1/WB1/MP2 WESTBAY MULTIPORT 2 77 75 85 ABS-1/1/WB1/MP3 WESTBAY MULTIPORT 3 257 255 265 AMD-1/1/WB1/MP1 WESTBAY MULTIPORT 1 105 104 114 AMD-1/1/WB1/MP2 WESTBAY MULTIPORT 2 135 135 145 AMD-1/1/WB1/MP3 WESTBAY MULTIPORT 3 180 180 190 AMD-1/1/WB1/MP4 WESTBAY MULTIPORT 4 245 246 256 AMD-1/1/WB1/MP5 WESTBAY MULTIPORT 5 329 330 340 AMD-1/1/WB1/MP6 WESTBAY MULTIPORT 6 383 384 394 AMD-1/1/WB1/MP7 WESTBAY MULTIPORT 7 523 524 534 AMD-1/1/WB1/MP8 WESTBAY MULTIPORT 8 762 760 770 AMD-1/1/WB1/MP9 WESTBAY MULTIPORT 9 1037 1038 1048 AMD-1/1/WB1/MP10 WESTBAY MULTIPORT 10 1392 1390 1400 AMD-2/1/WB1/MP1 WESTBAY MULTIPORT 1 157 156 166 AMD-2/1/WB1/MP2 WESTBAY MULTIPORT 2 262 260 270 AMD-2/1/WB1/MP3 WESTBAY MULTIPORT 3 387 384 394 AMD-2/1/WB1/MP4 WESTBAY MULTIPORT 4 512 510 520 AMD-2/1/WB1/MP5 WESTBAY MULTIPORT 5 659 658 668 AMD-2/1/WB1/MP6 WESTBAY MULTIPORT 6 824 820 830 AMD-2/1/WB1/MP7 WESTBAY MULTIPORT 7 1014 1012 1022 AMD-2/1/WB1/MP8 WESTBAY MULTIPORT 8 1154 1150 1160 AMD-2/1/WB1/MP9 WESTBAY MULTIPORT 9 1294 1290 1300 AMD-2/1/WB1/MP10 WESTBAY MULTIPORT 10 1444 1440 1450 AMD-3/1/WB1/MP1 WESTBAY MULTIPORT 1 65 66 76 AMD-3/1/WB1/MP2 WESTBAY MULTIPORT 2 135 134 144 AMD-3/1/WB1/MP3 WESTBAY MULTIPORT 3 210 210 220 AMD-3/1/WB1/MP4 WESTBAY MULTIPORT 4 360 360 370 AMD-3/1/WB1/MP5 WESTBAY MULTIPORT 5 480 480 490 AMD-3/1/WB1/MP6 WESTBAY MULTIPORT 6 569 570 580 AMD-3/1/WB1/MP7 WESTBAY MULTIPORT 7 823 820 830 AMD-3/1/WB1/MP8 WESTBAY MULTIPORT 8 923 920 930 AMD-3/1/WB1/MP9 WESTBAY MULTIPORT 9 1173 1170 1180 AMD-3/1/WB1/MP10 WESTBAY MULTIPORT 10 1283 1282 1292 AMD-4/1/WB1/MP1 WESTBAY MULTIPORT 1 206 204 214 AMD-4/1/WB1/MP2 WESTBAY MULTIPORT 2 296 295 305 AMD-4/1/WB1/MP3 WESTBAY MULTIPORT 3 381 380 390 AMD-4/1/WB1/MP4 WESTBAY MULTIPORT 4 561 560 570 AMD-4/1/WB1/MP5 WESTBAY MULTIPORT 5 702 700 710 AMD-4/1/WB1/MP6 WESTBAY MULTIPORT 6 794 790 800 AMD-4/1/WB1/MP7 WESTBAY MULTIPORT 7 939 935 945 AMD-4/1/WB1/MP8 WESTBAY MULTIPORT 8 1059 1055 1065 AMD-4/1/WB1/MP9 WESTBAY MULTIPORT 9 1124 1120 1130 AMD-4/1/WB1/MP10 WESTBAY MULTIPORT 10 1269 1265 1275 AMD-4/1/WB1/MP11 WESTBAY MULTIPORT 11 1409 1405 1415 AMD-5/1/WB1/MP1 WESTBAY MULTIPORT 1 101 100 110 AMD-5/1/WB1/MP2 WESTBAY MULTIPORT 2 201 200 210 AMD-5/1/WB1/MP3 WESTBAY MULTIPORT 3 301 300 310 AMD-5/1/WB1/MP4 WESTBAY MULTIPORT 4 415 414 424 AMD-5/1/WB1/MP5 WESTBAY MULTIPORT 5 497 495 505 AMD-5/1/WB1/MP6 WESTBAY MULTIPORT 6 642 640 650 AMD-5/1/WB1/MP7 WESTBAY MULTIPORT 7 754 750 760 1 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) AMD-5/1/WB1/MP8 WESTBAY MULTIPORT 8 924 920 930 AMD-5/1/WB1/MP9 WESTBAY MULTIPORT 9 1029 1025 1035 AMD-5/1/WB1/MP10 WESTBAY MULTIPORT 10 1214 1210 1220 AMD-5/1/WB1/MP11 WESTBAY MULTIPORT 11 1324 1320 1330 AMD-5/1/WB1/MP12 WESTBAY MULTIPORT 12 1424 1420 1430 AMD-6/1/WB1/MP1 WESTBAY MULTIPORT 1 112 110 120 AMD-6/1/WB1/MP2 WESTBAY MULTIPORT 2 152 150 160 AMD-6/1/WB1/MP3 WESTBAY MULTIPORT 3 222 220 230 AMD-6/1/WB1/MP4 WESTBAY MULTIPORT 4 277 275 285 AMD-6/1/WB1/MP5 WESTBAY MULTIPORT 5 372 370 380 AMD-6/1/WB1/MP6 WESTBAY MULTIPORT 6 497 495 505 AMD-6/1/WB1/MP7 WESTBAY MULTIPORT 7 622 620 630 AMD-6/1/WB1/MP8 WESTBAY MULTIPORT 8 714 710 720 AMD-6/1/WB1/MP9 WESTBAY MULTIPORT 9 794 790 800 AMD-6/1/WB1/MP10 WESTBAY MULTIPORT 10 904 900 910 AMD-6/1/WB1/MP11 WESTBAY MULTIPORT 11 1094 1090 1100 AMD-6/1/WB1/MP12 WESTBAY MULTIPORT 12 1264 1260 1270 AMD-6/1/WB1/MP13 WESTBAY MULTIPORT 13 1409 1405 1415 AMD-7/1/WB1/MP1 WESTBAY MULTIPORT 1 121 120 130 AMD-7/1/WB1/MP2 WESTBAY MULTIPORT 2 221 220 230 AMD-7/1/WB1/MP3 WESTBAY MULTIPORT 3 271 270 280 AMD-7/1/WB1/MP4 WESTBAY MULTIPORT 4 311 310 320 AMD-7/1/WB1/MP5 WESTBAY MULTIPORT 5 371 370 380 AMD-7/1/WB1/MP6 WESTBAY MULTIPORT 6 471 470 480 AMD-7/1/WB1/MP7 WESTBAY MULTIPORT 7 580 578 588 AMD-7/1/WB1/MP8 WESTBAY MULTIPORT 8 694 690 700 AMD-7/1/WB1/MP9 WESTBAY MULTIPORT 9 809 805 815 AMD-7/1/WB1/MP10 WESTBAY MULTIPORT 10 934 930 940 AMD-7/1/WB1/MP11 WESTBAY MULTIPORT 11 1074 1070 1080 AMD-7/1/WB1/MP12 WESTBAY MULTIPORT 12 1169 1165 1175 AMD-7/1/WB1/MP13 WESTBAY MULTIPORT 13 1299 1295 1305 AMD-7/1/WB1/MP14 WESTBAY MULTIPORT 14 1424 1420 1430 AMD-8/1/WB1/MP1 WESTBAY MULTIPORT 1 80 78 88 AMD-8/1/WB1/MP2 WESTBAY MULTIPORT 2 180 178 188 AMD-8/1/WB1/MP3 WESTBAY MULTIPORT 3 315 314 324 AMD-8/1/WB1/MP4 WESTBAY MULTIPORT 4 525 524 534 AMD-8/1/WB1/MP5 WESTBAY MULTIPORT 5 662 660 670 AMD-8/1/WB1/MP6 WESTBAY MULTIPORT 6 764 760 770 AMD-8/1/WB1/MP7 WESTBAY MULTIPORT 7 859 856 866 AMD-8/1/WB1/MP8 WESTBAY MULTIPORT 8 1004 1000 1010 AMD-8/1/WB1/MP9 WESTBAY MULTIPORT 9 1164 1160 1170 AMD-8/1/WB1/MP10 WESTBAY MULTIPORT 10 1289 1286 1296 AMD-8/1/WB1/MP11 WESTBAY MULTIPORT 11 1454 1450 1460 AMD-8/1/WB1/MP12 WESTBAY MULTIPORT 12 1569 1564 1574 AMD-8/1/WB1/MP13 WESTBAY MULTIPORT 13 1764 1760 1770 AMD-8/1/WB1/MP14 WESTBAY MULTIPORT 14 1949 1944 1954 AMD-8/1/WB1/MP15 WESTBAY MULTIPORT 15 2014 2010 2020 BPM-1/1/WB1/MP1 WESTBAY MULTIPORT 1 129 128 138 BPM-1/1/WB1/MP2 WESTBAY MULTIPORT 2 249 248 258 BPM-1/1/WB1/MP3 WESTBAY MULTIPORT 3 458 456 466 BPM-1/1/WB1/MP4 WESTBAY MULTIPORT 4 613 612 622 2 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) BPM-1/1/WB1/MP5 WESTBAY MULTIPORT 5 780 776 786 BPM-1/1/WB1/MP6 WESTBAY MULTIPORT 6 890 886 896 BPM-1/1/WB1/MP7 WESTBAY MULTIPORT 7 1040 1036 1046 BPM-1/1/WB1/MP8 WESTBAY MULTIPORT 8 1267 1264 1274 BPM-1/1/WB1/MP9 WESTBAY MULTIPORT 9 1392 1388 1398 BPM-1/1/WB1/MP10 WESTBAY MULTIPORT 10 1502 1498 1508 BPM-1/1/WB1/MP11 WESTBAY MULTIPORT 11 1687 1684 1694 BPM-1/1/WB1/MP12 WESTBAY MULTIPORT 12 1804 1800 1810 BPM-1/1/WB1/MP13 WESTBAY MULTIPORT 13 1934 1930 1940 BPM-1/1/WB1/MP14 WESTBAY MULTIPORT 14 2109 2105 2115 BPM-2/1/WB1/MP1 WESTBAY MULTIPORT 1 181 180 190 BPM-2/1/WB1/MP2 WESTBAY MULTIPORT 2 336 336 346 BPM-2/1/WB1/MP3 WESTBAY MULTIPORT 3 496 494 504 BPM-2/1/WB1/MP4 WESTBAY MULTIPORT 4 581 580 590 BPM-2/1/WB1/MP5 WESTBAY MULTIPORT 5 778 774 784 BPM-2/1/WB1/MP6 WESTBAY MULTIPORT 6 903 900 910 BPM-2/1/WB1/MP7 WESTBAY MULTIPORT 7 1028 1024 1034 BPM-2/1/WB1/MP8 WESTBAY MULTIPORT 8 1243 1240 1250 BPM-2/1/WB1/MP9 WESTBAY MULTIPORT 9 1367 1364 1374 BPM-2/1/WB1/MP10 WESTBAY MULTIPORT 10 1494 1490 1500 BPM-2/1/WB1/MP11 WESTBAY MULTIPORT 11 1614 1610 1620 BPM-2/1/WB1/MP12 WESTBAY MULTIPORT 12 1764 1760 1770 BPM-2/1/WB1/MP13 WESTBAY MULTIPORT 13 1931 1928 1938 BPM-2/1/WB1/MP14 WESTBAY MULTIPORT 14 2073 2070 2080 BPM-2/1/WB1/MP15 WESTBAY MULTIPORT 15 2173 2170 2180 CB-1/1/WB2/MP1 WESTBAY MULTIPORT 1 78 76 86 CB-1/1/WB2/MP2 WESTBAY MULTIPORT 2 143 140 150 CB-1/1/WB2/MP3 WESTBAY MULTIPORT 3 443 440 450 CB-1/1/WB2/MP4 WESTBAY MULTIPORT 4 663 659 669 CB-1/1/WB2/MP5 WESTBAY MULTIPORT 5 873 870 880 CB-1/1/WB2/MP6 WESTBAY MULTIPORT 6 1053 1050 1060 CB-1/1/WB2/MP7 WESTBAY MULTIPORT 7 1193 1190 1200 CB-1/1/WB2/MP8 WESTBAY MULTIPORT 8 1333 1329 1339 CB-1/1/WB2/MP9 WESTBAY MULTIPORT 9 1463 1460 1470 COSM-1/1/WB1/MP1 WESTBAY MULTIPORT 1 92 90 100 COSM-1/1/WB1/MP2 WESTBAY MULTIPORT 2 154 152 162 COSM-1/1/WB1/MP3 WESTBAY MULTIPORT 3 271 270 280 COSM-1/1/WB1/MP4 WESTBAY MULTIPORT 4 351 350 360 COSM-1/1/WB1/MP5 WESTBAY MULTIPORT 5 451 450 460 COSM-1/1/WB1/MP6 WESTBAY MULTIPORT 6 541 540 550 COSM-1/1/WB1/MP7 WESTBAY MULTIPORT 7 621 620 630 COSM-1/1/WB1/MP8 WESTBAY MULTIPORT 8 723 720 730 COSM-1/1/WB1/MP9 WESTBAY MULTIPORT 9 853 850 860 COSM-1/1/WB1/MP10 WESTBAY MULTIPORT 10 983 980 990 COSM-1/1/WB1/MP11 WESTBAY MULTIPORT 11 1103 1100 1110 COSM-1/1/WB1/MP12 WESTBAY MULTIPORT 12 1215 1212 1222 COSM-1/1/WB1/MP13 WESTBAY MULTIPORT 13 1435 1432 1442 COSM-1/1/WB1/MP14 WESTBAY MULTIPORT 14 1599 1594 1604 COSM-1/1/WB1/MP15 WESTBAY MULTIPORT 15 1764 1760 1770 COSM-2/1/WB1/MP1 WESTBAY MULTIPORT 1 60 58 68 COSM-2/1/WB1/MP2 WESTBAY MULTIPORT 2 115 113 123 3 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) COSM-2/1/WB1/MP3 WESTBAY MULTIPORT 3 202 198 208 COSM-2/1/WB1/MP4 WESTBAY MULTIPORT 4 309 307 317 COSM-2/1/WB1/MP5 WESTBAY MULTIPORT 5 409 406 416 COSM-2/1/WB1/MP6 WESTBAY MULTIPORT 6 541 540 550 COSM-2/1/WB1/MP7 WESTBAY MULTIPORT 7 651 649 659 COSM-2/1/WB1/MP8 WESTBAY MULTIPORT 8 763 757 767 COSM-2/1/WB1/MP9 WESTBAY MULTIPORT 9 890 886 896 COSM-2/1/WB1/MP10 WESTBAY MULTIPORT 10 1055 1051 1061 FFS-1/1/WB2/MP1 WESTBAY MULTIPORT 1 181 180 190 FFS-1/1/WB2/MP2 WESTBAY MULTIPORT 2 361 360 370 FFS-1/1/WB2/MP3 WESTBAY MULTIPORT 3 530 529 539 FFS-1/1/WB2/MP4 WESTBAY MULTIPORT 4 820 819 829 FFS-1/1/WB2/MP5 WESTBAY MULTIPORT 5 1060 1059 1069 FFS-1/1/WB2/MP6 WESTBAY MULTIPORT 6 1160 1159 1169 FFS-1/1/WB2/MP7 WESTBAY MULTIPORT 7 1300 1299 1309 FFS-1/1/WB2/MP8 WESTBAY MULTIPORT 8 1420 1419 1429 FVM-1/1/WB2/MP1 WESTBAY MULTIPORT 1 136 134 145 FVM-1/1/WB2/MP2 WESTBAY MULTIPORT 2 173 172 182 FVM-1/1/WB2/MP3 WESTBAY MULTIPORT 3 223 220 230 FVM-1/1/WB2/MP4 WESTBAY MULTIPORT 4 360 360 370 FVM-1/1/WB2/MP5 WESTBAY MULTIPORT 5 450 450 460 FVM-1/1/WB2/MP6 WESTBAY MULTIPORT 6 500 500 510 FVM-1/1/WB2/MP7 WESTBAY MULTIPORT 7 560 560 570 FVM-1/1/WB2/MP8 WESTBAY MULTIPORT 8 632 630 640 FVM-1/1/WB2/MP9 WESTBAY MULTIPORT 9 814 810 820 FVM-1/1/WB2/MP10 WESTBAY MULTIPORT 10 896 894 904 FVM-1/1/WB2/MP11 WESTBAY MULTIPORT 11 1003 1000 1010 FVM-1/1/WB2/MP12 WESTBAY MULTIPORT 12 1123 1120 1130 FVM-1/1/WB2/MP13 WESTBAY MULTIPORT 13 1178 1175 1185 FVM-1/1/WB2/MP14 WESTBAY MULTIPORT 14 1233 1230 1240 FVM-1/1/WB2/MP15 WESTBAY MULTIPORT 15 1323 1320 1330 FVM-1/1/WB2/MP16 WESTBAY MULTIPORT 16 1497 1492 1502 FVM-1/1/WB2/MP17 WESTBAY MULTIPORT 17 1587 1582 1592 FVM-1/1/WB2/MP18 WESTBAY MULTIPORT 18 1837 1834 1844 GGM-1/1/WB1/MP1 WESTBAY MULTIPORT 1 150 150 160 GGM-1/1/WB1/MP2 WESTBAY MULTIPORT 2 300 300 310 GGM-1/1/WB1/MP3 WESTBAY MULTIPORT 3 465 464 474 GGM-1/1/WB1/MP4 WESTBAY MULTIPORT 4 552 550 560 GGM-1/1/WB1/MP5 WESTBAY MULTIPORT 5 744 740 750 GGM-1/1/WB1/MP6 WESTBAY MULTIPORT 6 829 825 835 GGM-1/1/WB1/MP7 WESTBAY MULTIPORT 7 954 950 960 GGM-1/1/WB1/MP8 WESTBAY MULTIPORT 8 1074 1070 1080 GGM-1/1/WB1/MP9 WESTBAY MULTIPORT 9 1264 1260 1270 GGM-1/1/WB1/MP10 WESTBAY MULTIPORT 10 1519 1515 1525 GGM-1/1/WB1/MP11 WESTBAY MULTIPORT 11 1654 1650 1660 GGM-1/1/WB1/MP12 WESTBAY MULTIPORT 12 1771 1768 1778 GGM-1/1/WB1/MP13 WESTBAY MULTIPORT 13 2011 2008 2018 GGM-2/1/WB1/MP1 WESTBAY MULTIPORT 1 213 212 222 GGM-2/1/WB1/MP2 WESTBAY MULTIPORT 2 295 294 304 GGM-2/1/WB1/MP3 WESTBAY MULTIPORT 3 462 460 470 GGM-2/1/WB1/MP4 WESTBAY MULTIPORT 4 719 715 725 4 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) GGM-2/1/WB1/MP5 WESTBAY MULTIPORT 5 954 950 960 GGM-2/1/WB1/MP6 WESTBAY MULTIPORT 6 1049 1045 1055 GGM-2/1/WB1/MP7 WESTBAY MULTIPORT 7 1149 1145 1155 GGM-2/1/WB1/MP8 WESTBAY MULTIPORT 8 1254 1250 1260 GGM-2/1/WB1/MP9 WESTBAY MULTIPORT 9 1489 1485 1495 GGM-2/1/WB1/MP10 WESTBAY MULTIPORT 10 1629 1625 1635 GGM-2/1/WB1/MP11 WESTBAY MULTIPORT 11 1744 1740 1750 GGM-2/1/WB1/MP12 WESTBAY MULTIPORT 12 1904 1900 1910 GGM-2/1/WB1/MP13 WESTBAY MULTIPORT 13 1994 1990 2000 GGM-3/1/WB1/MP1 WESTBAY MULTIPORT 1 197 195 205 GGM-3/1/WB1/MP2 WESTBAY MULTIPORT 2 312 310 320 GGM-3/1/WB1/MP3 WESTBAY MULTIPORT 3 547 545 555 GGM-3/1/WB1/MP4 WESTBAY MULTIPORT 4 642 640 650 GGM-3/1/WB1/MP5 WESTBAY MULTIPORT 5 842 837 847 GGM-3/1/WB1/MP6 WESTBAY MULTIPORT 6 1007 1004 1014 GGM-3/1/WB1/MP7 WESTBAY MULTIPORT 7 1107 1104 1114 GGM-3/1/WB1/MP8 WESTBAY MULTIPORT 8 1279 1274 1284 GGM-3/1/WB1/MP9 WESTBAY MULTIPORT 9 1544 1539 1549 GGM-3/1/WB1/MP10 WESTBAY MULTIPORT 10 1684 1680 1690 GGM-3/1/WB1/MP11 WESTBAY MULTIPORT 11 1784 1780 1790 GGM-3/1/WB1/MP12 WESTBAY MULTIPORT 12 1954 1950 1960 HBM-1/1/WB1/MP1 WESTBAY MULTIPORT 1 91 90 100 HBM-1/1/WB1/MP2 WESTBAY MULTIPORT 2 191 190 200 HBM-1/1/WB1/MP3 WESTBAY MULTIPORT 3 321 320 330 HBM-1/1/WB1/MP4 WESTBAY MULTIPORT 4 483 482 492 HBM-1/1/WB1/MP5 WESTBAY MULTIPORT 5 562 560 570 HBM-1/1/WB1/MP6 WESTBAY MULTIPORT 6 702 700 710 HBM-1/1/WB1/MP7 WESTBAY MULTIPORT 7 924 920 930 HBM-1/1/WB1/MP8 WESTBAY MULTIPORT 8 1038 1034 1044 HBM-1/1/WB1/MP9 WESTBAY MULTIPORT 9 1130 1126 1136 HBM-1/1/WB1/MP10 WESTBAY MULTIPORT 10 1352 1348 1358 HBM-1/1/WB1/MP11 WESTBAY MULTIPORT 11 1464 1460 1470 HBM-1/1/WB1/MP12 WESTBAY MULTIPORT 12 1544 1540 1550 HBM-1/1/WB1/MP13 WESTBAY MULTIPORT 13 1644 1640 1650 HBM-1/1/WB1/MP14 WESTBAY MULTIPORT 14 1934 1930 1940 HBM-2/1/WB1/MP1 WESTBAY MULTIPORT 1 112 110 120 HBM-2/1/WB1/MP2 WESTBAY MULTIPORT 2 162 160 170 HBM-2/1/WB1/MP3 WESTBAY MULTIPORT 3 247 245 255 HBM-2/1/WB1/MP4 WESTBAY MULTIPORT 4 307 305 315 HBM-2/1/WB1/MP5 WESTBAY MULTIPORT 5 362 360 370 HBM-2/1/WB1/MP6 WESTBAY MULTIPORT 6 447 445 455 HBM-2/1/WB1/MP7 WESTBAY MULTIPORT 7 522 520 530 HBM-2/1/WB1/MP8 WESTBAY MULTIPORT 8 572 570 580 HBM-2/1/WB1/MP9 WESTBAY MULTIPORT 9 677 675 685 HBM-2/1/WB1/MP10 WESTBAY MULTIPORT 10 739 735 745 HBM-2/1/WB1/MP11 WESTBAY MULTIPORT 11 849 845 855 HBM-2/1/WB1/MP12 WESTBAY MULTIPORT 12 929 925 935 HBM-4/1/WB1/MP1 WESTBAY MULTIPORT 1 75 75 85 HBM-4/1/WB1/MP2 WESTBAY MULTIPORT 2 120 120 130 HBM-4/1/WB1/MP3 WESTBAY MULTIPORT 3 179 180 190 HBM-4/1/WB1/MP4 WESTBAY MULTIPORT 4 231 230 240 5 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) HBM-4/1/WB1/MP5 WESTBAY MULTIPORT 5 296 295 305 HBM-4/1/WB1/MP6 WESTBAY MULTIPORT 6 351 350 360 HBM-4/1/WB1/MP7 WESTBAY MULTIPORT 7 416 415 425 HBM-4/1/WB1/MP8 WESTBAY MULTIPORT 8 551 550 560 HBM-4/1/WB1/MP9 WESTBAY MULTIPORT 9 691 690 700 HBM-5/1/WB1/MP3 WESTBAY MULTIPORT 3 86 70 90 HBM-5/1/WB1/MP1 WESTBAY MULTIPORT 1 71 70 90 HBM-5/1/WB1/MP2 WESTBAY MULTIPORT 2 76 70 90 HBM-5/1/WB1/MP4 WESTBAY MULTIPORT 4 126 125 135 HBM-5/1/WB1/MP5 WESTBAY MULTIPORT 5 171 170 180 HBM-5/1/WB1/MP6 WESTBAY MULTIPORT 6 216 215 225 HBM-5/1/WB1/MP7 WESTBAY MULTIPORT 7 248 245 255 HBM-5/1/WB1/MP8 WESTBAY MULTIPORT 8 273 270 280 HBM-6/1/WB1/MP1 WESTBAY MULTIPORT 1 53 52 62 HBM-6/1/WB1/MP2 WESTBAY MULTIPORT 2 85 84 94 HBM-6/1/WB1/MP3 WESTBAY MULTIPORT 3 110 108 118 HBM-6/1/WB1/MP4 WESTBAY MULTIPORT 4 215 214 224 HBM-6/1/WB1/MP5 WESTBAY MULTIPORT 5 264 263 273 HBM-6/1/WB1/MP6 WESTBAY MULTIPORT 6 296 294 304 HBM-6/1/WB1/MP7 WESTBAY MULTIPORT 7 508 506 516 HBM-6/1/WB1/MP8 WESTBAY MULTIPORT 8 578 576 586 IDM-1/1/WB2/MP1 WESTBAY MULTIPORT 1 86 85 95 IDM-1/1/WB2/MP2 WESTBAY MULTIPORT 2 271 270 280 IDM-1/1/WB2/MP3 WESTBAY MULTIPORT 3 336 335 345 IDM-1/1/WB2/MP4 WESTBAY MULTIPORT 4 436 435 445 IDM-1/1/WB2/MP5 WESTBAY MULTIPORT 5 631 630 640 IDM-1/1/WB2/MP6 WESTBAY MULTIPORT 6 703 700 710 IDM-1/1/WB2/MP7 WESTBAY MULTIPORT 7 763 760 770 IDM-1/1/WB2/MP8 WESTBAY MULTIPORT 8 878 875 885 IDM-1/1/WB2/MP9 WESTBAY MULTIPORT 9 [PHONE REDACTED] IDM-1/1/WB2/MP10 WESTBAY MULTIPORT 10 1053 1050 1060 IDM-2/1/WB1/MP1 WESTBAY MULTIPORT 1 129 126 136 IDM-2/1/WB1/MP2 WESTBAY MULTIPORT 2 236 234 244 IDM-2/1/WB1/MP3 WESTBAY MULTIPORT 3 286 284 294 IDM-2/1/WB1/MP4 WESTBAY MULTIPORT 4 353 352 362 IDM-2/1/WB1/MP5 WESTBAY MULTIPORT 5 493 492 502 IDM-2/1/WB1/MP6 WESTBAY MULTIPORT 6 613 612 622 IDM-2/1/WB1/MP7 WESTBAY MULTIPORT 7 713 710 720 IDM-2/1/WB1/MP8 WESTBAY MULTIPORT 8 890 886 896 IDM-2/1/WB1/MP9 WESTBAY MULTIPORT 9 1055 1050 1060 IDM-2/1/WB1/MP10 WESTBAY MULTIPORT 10 1182 1178 1188 IDM-2/1/WB1/MP11 WESTBAY MULTIPORT 11 1259 1256 1266 IDM-2/1/WB1/MP12 WESTBAY MULTIPORT 12 1404 1400 1410 KBS-2/1/WB1/MP1 WESTBAY MULTIPORT 1 99 96 106 KBS-2/1/WB1/MP2 WESTBAY MULTIPORT 2 214 210 220 LAM-1/1/WB1/MP1 WESTBAY MULTIPORT 1 72 70 80 LAM-1/1/WB1/MP2 WESTBAY MULTIPORT 2 222 220 230 LAM-1/1/WB1/MP3 WESTBAY MULTIPORT 3 272 270 280 LAM-1/1/WB1/MP4 WESTBAY MULTIPORT 4 472 470 480 LAM-1/1/WB1/MP5 WESTBAY MULTIPORT 5 572 570 580 LAM-1/1/WB1/MP6 WESTBAY MULTIPORT 6 834 830 840 6 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) LAM-1/1/WB1/MP7 WESTBAY MULTIPORT 7 [PHONE REDACTED] LAM-1/1/WB1/MP8 WESTBAY MULTIPORT 8 1073 1070 1080 LAM-1/1/WB1/MP9 WESTBAY MULTIPORT 9 1153 1150 1160 LAM-1/1/WB1/MP10 WESTBAY MULTIPORT 10 1253 1250 1260 LAM-1/1/WB1/MP11 WESTBAY MULTIPORT 11 1498 1494 1504 LAM-1/1/WB1/MP12 WESTBAY MULTIPORT 12 1613 1610 1620 MCAS-1/1/WB2/MP1 WESTBAY MULTIPORT 1 65 60 70 MCAS-1/1/WB2/MP2 WESTBAY MULTIPORT 2 155 150 160 MCAS-1/1/WB2/MP3 WESTBAY MULTIPORT 3 215 210 220 MCAS-1/1/WB2/MP4 WESTBAY MULTIPORT 4 275 270 280 MCAS-1/1/WB2/MP5 WESTBAY MULTIPORT 5 335 330 340 MCAS-1/1/WB2/MP6 WESTBAY MULTIPORT 6 455 450 460 MCAS-1/1/WB2/MP7 WESTBAY MULTIPORT 7 545 540 550 MCAS-2/1/WB2/MP1 WESTBAY MULTIPORT 1 45 40 50 MCAS-2/1/WB2/MP2 WESTBAY MULTIPORT 2 135 130 140 MCAS-2/1/WB2/MP3 WESTBAY MULTIPORT 3 205 200 210 MCAS-2/1/WB2/MP4 WESTBAY MULTIPORT 4 375 370 380 MCAS-2/1/WB2/MP5 WESTBAY MULTIPORT 5 425 420 430 MCAS-2/1/WB2/MP6 WESTBAY MULTIPORT 6 495 490 500 MCAS-2/1/WB2/MP7 WESTBAY MULTIPORT 7 555 550 560 MCAS-2/1/WB2/MP8 WESTBAY MULTIPORT 8 625 620 630 MCAS-3/1/WB2/MP1 WESTBAY MULTIPORT 1 91 80 90 MCAS-3/1/WB2/MP2 WESTBAY MULTIPORT 2 166 160 170 MCAS-3/1/WB2/MP3 WESTBAY MULTIPORT 3 226 220 230 MCAS-3/1/WB2/MP4 WESTBAY MULTIPORT 4 346 340 350 MCAS-3/1/WB2/MP5 WESTBAY MULTIPORT 5 426 420 430 MCAS-3/1/WB2/MP6 WESTBAY MULTIPORT 6 496 490 500 MCAS-7/1/WB3/MP1 WESTBAY MULTIPORT 1 92 90 100 MCAS-7/1/WB3/MP2 WESTBAY MULTIPORT 2 192 190 200 MCAS-7/1/WB3/MP3 WESTBAY MULTIPORT 3 352 350 360 MCAS-7/1/WB3/MP4 WESTBAY MULTIPORT 4 442 440 450 MCAS-7/1/WB3/MP5 WESTBAY MULTIPORT 5 512 510 520 MCAS-7/1/WB3/MP6 WESTBAY MULTIPORT 6 802 800 810 MCAS-7/1/WB3/MP7 WESTBAY MULTIPORT 7 912 910 920 MCAS-7/1/WB3/MP8 WESTBAY MULTIPORT 8 982 980 990 MCAS-7/1/WB3/MP9 WESTBAY MULTIPORT 9 1082 1100 1110 SAR-1/1/WB2/MP1 WESTBAY MULTIPORT 1 162 150 170 SAR-1/1/WB2/MP2 WESTBAY MULTIPORT 2 297 290 300 SAR-1/1/WB2/MP3 WESTBAY MULTIPORT 3 327 320 330 SAR-1/1/WB2/MP4 WESTBAY MULTIPORT 4 367 360 370 SAR-1/1/WB2/MP5 WESTBAY MULTIPORT 5 519 510 530 SAR-1/1/WB2/MP6 WESTBAY MULTIPORT 6 584 580 590 SAR-1/1/WB2/MP7 WESTBAY MULTIPORT 7 829 820 840 SAR-1/1/WB2/MP8 WESTBAY MULTIPORT 8 894 890 900 SAR-1/1/WB2/MP9 WESTBAY MULTIPORT 9 914 910 920 SAR-1/1/WB2/MP10 WESTBAY MULTIPORT 10 1014 1010 1020 SAR-1/1/WB2/MP11 WESTBAY MULTIPORT 11 1114 1110 1120 SAR-1/1/WB2/MP12 WESTBAY MULTIPORT 12 1284 1280 1290 SAR-1/1/WB2/MP13 WESTBAY MULTIPORT 13 1374 1370 1380 SAR-1/1/WB2/MP14 WESTBAY MULTIPORT 14 1446 1441 1451 SAR-2/1/WB2/MP1 WESTBAY MULTIPORT 1 141 140 150 7 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) SAR-2/1/WB2/MP2 WESTBAY MULTIPORT 2 271 270 280 SAR-2/1/WB2/MP3 WESTBAY MULTIPORT 3 311 310 320 SAR-2/1/WB2/MP4 WESTBAY MULTIPORT 4 417 470 480 SAR-2/1/WB2/MP5 WESTBAY MULTIPORT 5 611 610 620 SAR-2/1/WB2/MP6 WESTBAY MULTIPORT 6 741 740 750 SAR-2/1/WB2/MP7 WESTBAY MULTIPORT 7 881 880 890 SAR-2/1/WB2/MP8 WESTBAY MULTIPORT 8 981 980 990 SAR-2/1/WB2/MP9 WESTBAY MULTIPORT 9 1021 1020 1030 SAR-2/1/WB2/MP10 WESTBAY MULTIPORT 10 1101 1100 1110 SAR-2/1/WB2/MP11 WESTBAY MULTIPORT 11 1231 1230 1240 SAR-2/1/WB2/MP12 WESTBAY MULTIPORT 12 1351 1350 1360 SAR-3/1/WB2/MP1 WESTBAY MULTIPORT 1 164 160 170 SAR-3/1/WB2/MP2 WESTBAY MULTIPORT 2 234 230 240 SAR-3/1/WB2/MP3 WESTBAY MULTIPORT 3 414 410 420 SAR-3/1/WB2/MP4 WESTBAY MULTIPORT 4 514 510 520 SAR-3/1/WB2/MP5 WESTBAY MULTIPORT 5 644 640 650 SAR-3/1/WB2/MP6 WESTBAY MULTIPORT 6 774 770 780 SAR-3/1/WB2/MP7 WESTBAY MULTIPORT 7 954 950 960 SAR-3/1/WB2/MP8 WESTBAY MULTIPORT 8 1074 1070 1080 SAR-3/1/WB2/MP9 WESTBAY MULTIPORT 9 1199 1195 1205 SAR-3/1/WB2/MP10 WESTBAY MULTIPORT 10 1269 1265 1275 SAR-3/1/WB2/MP11 WESTBAY MULTIPORT 11 1393 1390 1400 SAR-4/1/WB2/MP1 WESTBAY MULTIPORT 1 123 115 125 SAR-4/1/WB2/MP2 WESTBAY MULTIPORT 2 328 320 330 SAR-4/1/WB2/MP3 WESTBAY MULTIPORT 3 478 470 480 SAR-4/1/WB2/MP4 WESTBAY MULTIPORT 4 598 590 600 SAR-4/1/WB2/MP5 WESTBAY MULTIPORT 5 738 730 740 SAR-4/1/WB2/MP6 WESTBAY MULTIPORT 6 868 860 870 SAR-4/1/WB2/MP7 WESTBAY MULTIPORT 7 978 970 980 SAR-4/1/WB2/MP8 WESTBAY MULTIPORT 8 1068 1060 1070 SAR-4/1/WB2/MP9 WESTBAY MULTIPORT 9 1168 1160 1170 SAR-4/1/WB2/MP10 WESTBAY MULTIPORT 10 1398 1395 1405 SAR-5/1/WB2/MP1 WESTBAY MULTIPORT 1 80 80 90 SAR-5/1/WB2/MP2 WESTBAY MULTIPORT 2 170 170 180 SAR-5/1/WB2/MP3 WESTBAY MULTIPORT 3 360 360 370 SAR-5/1/WB2/MP4 WESTBAY MULTIPORT 4 617 616 626 SAR-5/1/WB2/MP5 WESTBAY MULTIPORT 5 764 760 770 SAR-5/1/WB2/MP6 WESTBAY MULTIPORT 6 944 940 950 SAR-5/1/WB2/MP7 WESTBAY MULTIPORT 7 1084 1080 1090 SAR-5/1/WB2/MP8 WESTBAY MULTIPORT 8 1193 1190 1200 SAR-5/1/WB2/MP9 WESTBAY MULTIPORT 9 1293 1290 1300 SAR-5/1/WB2/MP10 WESTBAY MULTIPORT 10 1543 1540 1550 SAR-5/1/WB2/MP11 WESTBAY MULTIPORT 11 1733 1730 1740 SAR-5/1/WB2/MP12 WESTBAY MULTIPORT 12 1823 1820 1830 SAR-6/1/WB2/MP1 WESTBAY MULTIPORT 1 206 200 210 SAR-6/1/WB2/MP2 WESTBAY MULTIPORT 2 366 360 370 SAR-6/1/WB2/MP3 WESTBAY MULTIPORT 3 476 470 480 SAR-6/1/WB2/MP4 WESTBAY MULTIPORT 4 581 574 584 SAR-6/1/WB2/MP5 WESTBAY MULTIPORT 5 706 700 710 SAR-6/1/WB2/MP6 WESTBAY MULTIPORT 6 786 780 790 SAR-6/1/WB2/MP7 WESTBAY MULTIPORT 7 1086 1080 1090 8 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) SAR-6/1/WB2/MP8 WESTBAY MULTIPORT 8 1186 1180 1190 SAR-6/1/WB2/MP9 WESTBAY MULTIPORT 9 1276 1270 1280 SAR-6/1/WB2/MP10 WESTBAY MULTIPORT 10 1501 1500 1510 SAR-7/1/WB2/MP1 WESTBAY MULTIPORT 1 111 110 120 SAR-7/1/WB2/MP2 WESTBAY MULTIPORT 2 171 170 180 SAR-7/1/WB2/MP3 WESTBAY MULTIPORT 3 310 310 320 SAR-7/1/WB2/MP4 WESTBAY MULTIPORT 4 440 440 450 SAR-7/1/WB2/MP5 WESTBAY MULTIPORT 5 605 604 614 SAR-7/1/WB2/MP6 WESTBAY MULTIPORT 6 742 740 750 SAR-7/1/WB2/MP7 WESTBAY MULTIPORT 7 862 856 866 SAR-7/1/WB2/MP8 WESTBAY MULTIPORT 8 1194 1190 1200 SAR-7/1/WB2/MP9 WESTBAY MULTIPORT 9 1354 1350 1360 SAR-8/1/WB1/MP1 WESTBAY MULTIPORT 1 44 34 44 SAR-8/1/WB1/MP2 WESTBAY MULTIPORT 2 94 84 94 SAR-8/1/WB1/MP3 WESTBAY MULTIPORT 3 159 150 160 SAR-9/1/WB1/MP1 WESTBAY MULTIPORT 1 150 148 160 SAR-9/1/WB1/MP2 WESTBAY MULTIPORT 2 239 236 248 SAR-9/1/WB1/MP3 WESTBAY MULTIPORT 3 409 406 418 SAR-9/1/WB1/MP4 WESTBAY MULTIPORT 4 491 488 500 SAR-9/1/WB1/MP5 WESTBAY MULTIPORT 5 606 604 616 SAR-9/1/WB1/MP6 WESTBAY MULTIPORT 6 730 724 736 SAR-9/1/WB1/MP7 WESTBAY MULTIPORT 7 877 872 884 SAR-9/1/WB1/MP8 WESTBAY MULTIPORT 8 1072 1068 1080 SAR-9/1/WB1/MP9 WESTBAY MULTIPORT 9 1262 1258 1270 SAR-9/1/WB1/MP10 WESTBAY MULTIPORT 10 1477 1473 1484 SAR-9/1/WB1/MP11 WESTBAY MULTIPORT 11 1572 1567 1578 SAR-9/1/WB1/MP12 WESTBAY MULTIPORT 12 1724 1719 1730 SAR-9/1/WB1/MP13 WESTBAY MULTIPORT 13 1821 1815 1826 SAR-9/1/WB1/MP14 WESTBAY MULTIPORT 14 1893 1889 1900 SBM-1/1/WB1/MP1 WESTBAY MULTIPORT 1 79 74 84 SBM-1/1/WB1/MP2 WESTBAY MULTIPORT 2 149 144 154 SBM-1/1/WB1/MP3 WESTBAY MULTIPORT 3 244 240 250 SBM-1/1/WB1/MP4 WESTBAY MULTIPORT 4 374 370 380 SBM-1/1/WB1/MP5 WESTBAY MULTIPORT 5 514 510 520 SBM-1/1/WB1/MP6 WESTBAY MULTIPORT 6 706 696 706 SBM-1/1/WB1/MP7 WESTBAY MULTIPORT 7 916 910 920 SBM-1/1/WB1/MP8 WESTBAY MULTIPORT 8 1256 1250 1260 SC-1/1/WB1/MP1 WESTBAY MULTIPORT 1 48 44 54 SC-1/1/WB1/MP2 WESTBAY MULTIPORT 2 93 90 100 SC-1/1/WB1/MP3 WESTBAY MULTIPORT 3 153 150 160 SC-1/1/WB1/MP4 WESTBAY MULTIPORT 4 197 194 204 SC-1/1/WB1/MP5 WESTBAY MULTIPORT 5 299 294 304 SC-1/1/WB1/MP6 WESTBAY MULTIPORT 6 394 390 400 SC-2/1/WB2/MP1 WESTBAY MULTIPORT 1 49 46 56 SC-2/1/WB2/MP2 WESTBAY MULTIPORT 2 96 94 104 SC-2/1/WB2/MP3 WESTBAY MULTIPORT 3 148 146 156 SC-2/1/WB2/MP4 WESTBAY MULTIPORT 4 192 190 200 SC-2/1/WB2/MP5 WESTBAY MULTIPORT 5 251 248 258 SC-2/1/WB2/MP6 WESTBAY MULTIPORT 6 303 300 310 SC-3/1/WB2/MP1 WESTBAY MULTIPORT 1 227 224 234 SC-3/1/WB2/MP2 WESTBAY MULTIPORT 2 412 410 420 9 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) SC-3/1/WB2/MP3 WESTBAY MULTIPORT 3 577 576 586 SC-3/1/WB2/MP4 WESTBAY MULTIPORT 4 712 710 720 SC-3/1/WB2/MP5 WESTBAY MULTIPORT 5 1022 1018 1028 SC-3/1/WB2/MP6 WESTBAY MULTIPORT 6 1154 1150 1160 SC-3/1/WB2/MP7 WESTBAY MULTIPORT 7 1234 1230 1240 SC-3/1/WB2/MP8 WESTBAY MULTIPORT 8 1374 1370 1380 SC-3/1/WB2/MP9 WESTBAY MULTIPORT 9 1459 1460 1470 SC-4/1/WB1/MP1 WESTBAY MULTIPORT 1 102 100 111 SC-4/1/WB1/MP2 WESTBAY MULTIPORT 2 201 198 209 SC-4/1/WB1/MP3 WESTBAY MULTIPORT 3 271 268 279 SC-4/1/WB1/MP4 WESTBAY MULTIPORT 4 393 391 402 SC-4/1/WB1/MP5 WESTBAY MULTIPORT 5 483 482 493 SC-4/1/WB1/MP6 WESTBAY MULTIPORT 6 573 572 583 SC-4/1/WB1/MP7 WESTBAY MULTIPORT 7 660 658 669 SC-4/1/WB1/MP8 WESTBAY MULTIPORT 8 830 827 838 SC-4/1/WB1/MP9 WESTBAY MULTIPORT 9 1082 1078 1089 SC-5/1/WB1/MP1 WESTBAY MULTIPORT 1 124 123 133 SC-5/1/WB1/MP2 WESTBAY MULTIPORT 2 196 196 206 SC-5/1/WB1/MP3 WESTBAY MULTIPORT 3 291 290 300 SC-5/1/WB1/MP4 WESTBAY MULTIPORT 4 470 468 478 SC-5/1/WB1/MP5 WESTBAY MULTIPORT 5 670 667 677 SC-5/1/WB1/MP6 WESTBAY MULTIPORT 6 807 804 814 SC-5/1/WB1/MP7 WESTBAY MULTIPORT 7 937 932 942 SC-5/1/WB1/MP8 WESTBAY MULTIPORT 8 1024 1020 1030 SC-5/1/WB1/MP9 WESTBAY MULTIPORT 9 1238 1234 1244 SC-5/1/WB1/MP10 WESTBAY MULTIPORT 10 1430 1426 1436 SC-6/1/WB1/MP1 WESTBAY MULTIPORT 1 92 90 100 SC-6/1/WB1/MP2 WESTBAY MULTIPORT 2 202 200 210 SC-6/1/WB1/MP3 WESTBAY MULTIPORT 3 302 300 310 SC-6/1/WB1/MP4 WESTBAY MULTIPORT 4 542 540 550 SC-6/1/WB1/MP5 WESTBAY MULTIPORT 5 789 785 795 SC-6/1/WB1/MP6 WESTBAY MULTIPORT 6 964 960 970 SC-6/1/WB1/MP7 WESTBAY MULTIPORT 7 1124 1120 1130 SC-6/1/WB1/MP8 WESTBAY MULTIPORT 8 1329 1325 1335 SC-6/1/WB1/MP9 WESTBAY MULTIPORT 9 1464 1460 1470 SC-6/1/WB1/MP10 WESTBAY MULTIPORT 10 1544 1540 1550 SC-6/1/WB1/MP11 WESTBAY MULTIPORT 11 1684 1680 1690 SC-6/1/WB1/MP12 WESTBAY MULTIPORT 12 1894 1890 1900 SC-6/1/WB1/MP13 WESTBAY MULTIPORT 13 2029 2025 2035 SC-6/1/WB1/MP14 WESTBAY MULTIPORT 14 2119 2115 2125 SCS-1/1/WB1/MP1 WESTBAY MULTIPORT 1 29 24 34 SCS-1/1/WB1/MP2 WESTBAY MULTIPORT 2 94 90 100 SCS-1/1/WB1/MP3 WESTBAY MULTIPORT 3 146 142 152 SCS-1/1/WB1/MP4 WESTBAY MULTIPORT 4 183 178 188 SCS-1/1/WB1/MP5 WESTBAY MULTIPORT 5 223 220 230 SCS-1/1/WB1/MP6 WESTBAY MULTIPORT 6 298 295 305 SCS-2/1/WB1/MP1 WESTBAY MULTIPORT 1 139 134 145 SCS-2/1/WB1/MP2 WESTBAY MULTIPORT 2 179 174 185 SCS-2/1/WB1/MP3 WESTBAY MULTIPORT 3 218 212 223 SCS-2/1/WB1/MP4 WESTBAY MULTIPORT 4 265 260 270 SCS-2/1/WB1/MP5 WESTBAY MULTIPORT 5 330 325 335 10 of 11 ---PAGE BREAK--- APPENDIX E - OCWD WESTBAY GROUNDWATER MONITORING WELLS MONITORING PORT INFORMATION Westbay Monitoring Port Name Well Type Monitoring Port No. Westbay Port Depth (ft.) Top of Zone (ft.) Bottom of Zone (ft.) WBS-2A/1/WB1/MP1 WESTBAY MULTIPORT 1 54 50 60 WBS-2A/1/WB1/MP2 WESTBAY MULTIPORT 2 94 90 100 WBS-2A/1/WB1/MP3 WESTBAY MULTIPORT 3 139 135 145 WBS-3/1/WB1/MP1 WESTBAY MULTIPORT 1 79 75 85 WBS-3/1/WB1/MP2 WESTBAY MULTIPORT 2 219 215 225 WMM-1/1/WB2/MP1 WESTBAY MULTIPORT 1 111 109 119 WMM-1/1/WB2/MP2 WESTBAY MULTIPORT 2 361 359 369 WMM-1/1/WB2/MP3 WESTBAY MULTIPORT 3 483 480 490 WMM-1/1/WB2/MP4 WESTBAY MULTIPORT 4 603 600 610 WMM-1/1/WB2/MP5 WESTBAY MULTIPORT 5 745 740 750 WMM-1/1/WB2/MP6 WESTBAY MULTIPORT 6 815 810 820 WMM-1/1/WB2/MP7 WESTBAY MULTIPORT 7 895 889 899 WMM-1/1/WB2/MP8 WESTBAY MULTIPORT 8 985 980 990 WMM-1/1/WB2/MP9 WESTBAY MULTIPORT 9 1065 1060 1070 WMM-1/1/WB2/MP10 WESTBAY MULTIPORT 10 1215 1210 1220 WMM-1/1/WB2/MP11 WESTBAY MULTIPORT 11 1315 1309 1319 WMM-1/1/WB2/MP12 WESTBAY MULTIPORT 12 1370 1364 1374 WMM-1/1/WB2/MP13 WESTBAY MULTIPORT 13 1435 1430 1440 WMM-1/1/WB2/MP14 WESTBAY MULTIPORT 14 1570 1565 1575 WMM-1/1/WB2/MP15 WESTBAY MULTIPORT 15 1625 1619 1629 WMM-1/1/WB2/MP16 WESTBAY MULTIPORT 16 1745 1740 1750 WMM-1/1/WB2/MP17 WESTBAY MULTIPORT 17 1805 1800 1810 WMM-1/1/WB2/MP18 WESTBAY MULTIPORT 18 1945 1940 1950 11 of 11 ---PAGE BREAK--- APPENDIX F ACRONYMS AND ABBREVIATIONS ---PAGE BREAK--- Abbreviations and Acronyms Groundwater Management Plan 2009 Update i Abbreviations and Acronyms The following abbreviations and acronyms are used in this report: ACOE U.S. Army Corps of Engineers af acre-feet afy acre-feet per year AOC assimiable organic carbon AOP advanced oxidation processes AWT advanced water treatment basin Orange County groundwater basin Basin Model OCWD groundwater model BEA Basin Equity Assessment BPP Basin Production Percentage CDFG California Department of Fish & Game CDPH California Department of Public Health cfs cubic feet per second CWTF Colored Water Treatment Facility DATS Deep Aquifer Treatment System District Orange County Water District DOC dissolved organic compound DWR Department of Water Resources DWSAP Drinking Water Source Assessment and Protection EDCs Endocrine Disrupting Compounds EIR Environmental Impact Report EPA U.S. Environmental Protection Agency FY fiscal year GAC granular activated carbon GIS geographic information system GWR Groundwater Replenishment H2O2 hydrogen peroxide IEUA Inland Empire Utilities Agency IRWD Irvine Ranch Water District K model layer hydraulic conductivity LACDWP Los Angeles County Department of Power & Water maf million acre feet MCAS Marine Corps Air Station MCL maximum contaminant level MCWD Mesa Consolidated Water District MWDOC Municipal Water District of Orange County MF microfiltration MODFLOW Computer program developed by USGS mgd million gallons per day mg/L milligrams per liter MTBE methyl tertiary-butylether Metropolitan Metropolitan Water District of Southern California ---PAGE BREAK--- Abbreviations and Acronyms Groundwater Management Plan 2009 Update ii MWDOC Municipal Water District of Orange County NDMA n-Nitrosodimethylamine NF nanofiltration ng/L nanograms per liter North Basin Groundwater Protection Program NO2 nitrite NO3 - Nitrate NPDES National Pollution Discharge Elimination System NWRI National Water Research Institute O&M operations and maintenance OCHCA Orange County Health Care Agency OCSD Orange County Sanitation District OCWD Orange County Water District PCE perchloroethylene Plan Groundwater Management Plan ppb less than one microgram per liter pharmaceuticals and personal care products Producers Orange County groundwater producers RA replenishment assessment REWG Recharge Enhancement Working Group RO reverse osmosis Regional Water Quality Control Board SARI Santa Ana River Interceptor SARWQH Santa Ana Regional Water Quality and Health SAWA Santa Ana Watershed Association SAWPA Santa Ana Watershed Project Authority South Basin Groundwater Protection Project SDWA Safe Drinking Water Act SOCs organic chemicals SWP State Water Project State Water Resource Control Board TCE trichloroethylene TDS total dissolved solids TIN total inorganic nitrogen µg/L micrograms per liter USFWS U.S. Fish & Wildlife Service USGS U.S. Geological Survey UV ultraviolet light VOCs volatile organic compounds WACO Water Advisory Committee of Orange County WF-21 Water Factory 21 WRD Water Replenishment District of Southern California WRMS Water Resources Management System