Orange County Water District captures Hilary rainfall to bolster water supplies

Aug. 24, 2023
The water district’s managed aquifer recharge system helped to capture 2.56 inches of rain from Tropical Storm Hilary.

The Orange County Water District (OCWD) announced that, with the arrival of Tropical Storm Hilary, it was able to capture 2.56 inches of rain and increase its water storage behind Prado Dam to more than 3.4 billion gallons of water.

Located in the northern part of the county lies OCWD’s managed aquifer recharge system where a series of rubber dams, pumps and percolation ponds work to get water into the Orange County Groundwater Basin.

Additionally, a historic cooperative agreement with the United States Army Corps of Engineers has continued to allow OCWD to store water behind Prado Dam. This pool of water can be strategically held back and released at rates that the District can capture through its recharge system, eventually flowing into the Basin and increasing local drinking water supplies.

The water storage currently held behind the dam is enough to serve 100,000 people for one year and is valued at an estimated $12.6 million, equivalent to the cost of imported water.

"Capturing stormwater has been part of the District’s diverse water supply portfolio for decades," said OCWD Board President Cathy Green. "Thanks to the incredible partnership with the Corps, we have continued to increase stormwater capture behind Prado Dam, which has proven to be an economical and effective solution to the region’s water challenges without compromising the safety of the dam."

To further enhance stormwater capture, OCWD is testing Forecast Informed Reservoir Operations (FIRO) at Prado Dam. With the support of the Scripps Institution of Oceanography at the University of California, San Diego and the Corps, FIRO aims to develop improved weather forecasting, including storms and atmospheric rivers, and ultimately update the Corps’ control manuals to increase water storage levels behind Prado Dam.

“OCWD is well positioned to maximize water supply for the region, during wet or dry times,” Green added. “Our long history of active water management and investments have ensured a sustainable groundwater basin that will serve generations to come.”

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