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Water Board oks water diversion to recharge aquifer

March 13, 2023

Reclamation to lower flood risk and increase infiltration

California’s wet winter, abundant snowpack and forecasted atmospheric rivers have increased flooding risk. The State Water Resources Control Board has approved a request by the U.S. Bureau of Reclamation to divert San Joaquin River floodwater to Central Valley groundwater basins from March 15 through July 30, 2023.

More than 600,000 acre-feet of water is anticipated to replenish depleted underground water supplies and surface waterbodies in San Luis National Wildlife Refuge, Mendota Wildlife Area, and Los Banos Wildlife Area along the river.

The federal agency petitioned the state to change its “San Joaquin River water rights at Friant Dam to manage flood flows.”

“Important opportunities remain for potential water capture during the remainder of the wet season,” commented Joaquin Esquivel, chair of the Water Board. The approval enables the capture of “high flows that would otherwise go unused.”

On Friday, March 13, Governor Gavin Newsom signed an executive order enabling the capture of water from the latest storms of the “pineapple express” variety.

The U.S. Bureau of Reclamation manages the dams, reservoirs and canals of the Central Valley Project, which distributes water to contractors including large irrigation districts, who serve agricultural producers.

Ernest Conant, regional director of Reclamation’s California-Great Basin Region said, “With this year’s record-breaking snowpack in the San Joaquin River Basin, Reclamation is diligently working to execute temporary water service contracts to ensure the best management of the projected large, unstorable flood flows.”

Groundwater accounts for up to 60% of California’s water supply in dry years, the state’s Water Supply Strategy seeks to expand replenishment of these basins — which have the ability to store 8-12 times more water than the state’s surface water reservoirs — by 500,000 acre-feet annually.

The order was approved on the condition that San Joaquin River flows must maintain the fish population; at least 300 cubic feet per second are bypassed to the river before additional diversions are permitted.