The Orange County Water District (OCWD) was formed as a special act district by the California State legislature in 1933 to manage the quantity and quality of the Orange County groundwater basin and protect its rights to Santa Ana River water. OCWD currently provides groundwater to 19 retailers that serve 2.5 million people within its 350 square mile service area. 

Since its formation, OCWD has steadily increased its Managed Aquifer Recharge (MAR) capacity starting with the purchase of land underlying six miles of the Santa Ana River.  It now owns and operates more than two dozen facilities covering over 1,000 wetted acres and a total storage capacity of approximately 26,000 acre-feet. Also included in this is the Talbert Seawater Intrusion Barrier, that serves to both protect the groundwater basin from seawater intrusion but also replenishes the basin with more than 95% of the injected water becoming part of the groundwater supply.  OCWD recharges water from the Santa Ana River, storm water, imported water and recycled water. 

In 2023, OCWD completed the final expansion of the Groundwater Replenishment System (GWRS).  The GWRS is the largest indirect-potable reuse facility in the world, producing 130 million gallons per day of highly purified recycled water.  GWRS water now makes up, on average, approximately 34 percent of the groundwater supplies to the basin. 

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GWRS Treatment Plant-Microfiltration System

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La Palma Recharge Basin, dedicated to the recharge of GWRS water.

OCWD is actively exploring opportunities to enhance its stormwater capture and recharge through Forecast Informed Reservoir Operations (FIRO).  FIRO is an innovative approach that provides resilience to the extreme variability in California precipitation, particularly Atmospheric Rivers (ARs) using modern forecasting methods to selectively retain or release water from reservoirs in anticipation of future weather conditions.  In collaboration with the US Army Corps of Engineers, the Center for Western Weather and Water Extremes conducted an assessment on the feasibility of implementing FIRO at Prado Dam.  The findings indicate that FIRO is a viable approach, capable of generating an additional 4,000 to 6,000 acre-feet per year for stormwater recharge—equivalent to sustaining 16,000 to 24,000 people annually.  OCWD is set to collaborate closely with the USACE to integrate FIRO as a permanent feature in the operations of Prado Dam.

To comply with the 2014 Sustainable Groundwater Management Act (SGMA), which requires groundwater basins in California to be managed sustainably based on avoiding six defined undesirable results, such as chronic overdraft and seawater intrusion, OCWD submitted an plan in 2017 that showed the basin was already being managed in a sustainable manner and was avoiding the six undesirable results defined in SGMA.  The plan was updated in 2022 and shows OCWD is continuing to sustainably manage the Orange County Groundwater Basin. 

Presently, OCWD replenishes the groundwater basin at an annual average of 320,000 acre-feet.  This recharge enables groundwater producers to meet 85 percent of their overall demands, with the remaining 15 percent sourced from imported water.  The Orange County groundwater basin's natural yield is approximately 100,000 acre-feet per year. Consequently, OCWD's investments in Managed Aquifer Recharge (MAR) have more than doubled the sustainable yield of the groundwater basin.

Contact: Adam Hutchinson, Recharge Planning Manager,