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2025 URBAN WATER MANAGEMENT PLAN <br /> MAY 2026/FINAL DRAFT/CAROLLO <br /> piloting of different treatment systems, and design and construction of treatment plants that are now <br /> operational. By 2025 OCWD had restored 49 wells to service with operational treatment systems, with an <br /> additional 57 wells in planning, design, or construction stages (Association of California Water Agencies, <br /> 2025). These systems continue to rely primarily on granular activated carbon and ion-exchange media <br /> operated in lead—lag configuration to achieve non-detect PFAS levels consistent with evolving state and <br /> federal regulatory standards (Santa Ana Regional Water Quality Control Board and OCWD, 2023). <br /> Groundwater production in FY 2023-24 totaled 280,420 acre-feet (AF), with slight increases projected over <br /> the next two years as additional treatment systems come online, showing continued reductions associated <br /> with PFAS-impacted wells that remain offline across several agencies. Salinity is a significant water quality <br /> problem in many parts of southern California, including Orange County. Salinity is a measure of the <br /> dissolved minerals in water including both TDS and nitrates. OCWD continuously monitors the levels of <br /> TDS in wells throughout the OC Basin. TDS currently has a California Secondary MCL of 500 milligrams per <br /> liter (mg/L). The portions of the OC Basin with the highest levels are generally located in the cities of <br /> Irvine, Tustin,Yorba Linda, Anaheim, and Fullerton.There is also a broad area in the central portion of the <br /> OC Basin where TDS ranges from 500 to 700 mg/L. Sources of TDS include the water supplies used to <br /> recharge the OC Basin and from onsite wastewater treatment systems, also known as septic systems. The <br /> TDS concentration in the OC Basin increased on average from 41S mg/L in 2022-23 to 432 mg/L in <br /> 2023-24 (OCWD, 2025). <br /> Nitrates are one of the most common and widespread contaminants in groundwater supplies, originating <br /> from fertilizer use, animal feedlots, wastewater disposal systems, and other sources.The MCL for nitrate in <br /> drinking water is set at 10 mg/L. OCWD regularly monitors nitrate levels in groundwater and works with <br /> producers to treat wells that have exceeded safe levels of nitrate concentrations. OCWD manages the <br /> nitrate concentration of water recharged by its facilities to reduce nitrate concentrations in groundwater. <br /> This includes the operation of the Prado Wetlands,which was designed to remove nitrogen and other <br /> pollutants from the Santa Ana River before the water is diverted to be percolated into OCWD's surface <br /> water recharge system.Although water from the deep aquifer system is of very high quality, it is <br /> amber-colored and contains a sulfuric odor due to buried natural organic material, requiring treatment <br /> before use as drinking water. The principal aquifer, which supplies most basin pumping, occurs at depths <br /> of roughly 300 to 1,200 feet below ground surface (OCWD, 2025).The total volume of amber-colored <br /> groundwater in the deep system is estimated at approximately 1 million acre-feet (MAF). <br /> 1.2.4 Locally Applicable Criteria <br /> Within Orange County, there are no significant local applicable criteria that directly affect reliability. Over <br /> the years, the water agencies in Orange County have made tremendous efforts to integrate their systems <br /> to provide flexibility for interchanging with different sources of supply.There are emergency agreements <br /> in place to provide adequate supply of water in all parts of the County. In the northern part of the County, <br /> agencies can meet most of their demands from groundwater with very little limitation, except for the <br /> OCWD BPP. For the agencies in south Orange County, most of their demands are met with imported <br /> water, and their limitations are based on the capacity of their systems, which are very robust. However, if a <br /> major earthquake on the San Andreas Fault occurs, it can potentially be damaging to key water aqueducts <br /> and disrupt imported supplies to the entire Southern California for up to six months.The MET region <br /> would likely require a water use reduction of 10 to 25 percent until the system is repaired. However, MET <br /> has taken proactive steps to handle such disruption, such as constructing DVL, which mitigates potential <br /> CITY OF SANTA ANA <br />