California’s groundwater supply received big boost from ’23 water year

California’s historic 2023 rainy season was a massive boost to the state’s groundwater supply, according to the California Department of Water Resources .

The agency said the 2023 water year was the first since 2019 that groundwater storage increased, rising by 8.7 million acre-feet in basins across the state.

The water year runs from Oct. 1 to Sept. 30, and is the official 12-month timeframe used by water managers to compile and compare hydrologic records, the state said.

The massive amount of rainfall allowed the state to pull less water from its groundwater reserves. About 9.5 million acre-feet was extracted in the this last water year, compared to the 17 million extracted in 2022.

In addition to that reduction, the 2023 water year, the eight wettest in the last five decades, allowed the state to recharge 4.1 million acre-feet to the state’s aquifers, the majority of which (93%) took place in the San Joaquin Valley.

State and local partner agencies were also able to use floodwaters to recharge more than 450,000 acre-feet of water into the groundwater supply.

“This success was made possible by proactive water management strategies that included swift regulatory streamlining measures and financial support from the state for infrastructure enhancements,” DWR said in its semiannual groundwater conditions update.

While encouraging, state officials said much work needs to be done to ensure California’s groundwater levels are replenished and healthy moving forward.

Precipitation in California has significantly decreased over the last several decades and groundwater was “routinely” extracted at a rate that exceeded the amount that was replenished.

Groundwater storage remains in a deficit of nearly 40 million-acre feet due to over-extraction over the past two decades.

“A single year, or even a few years, of heavy precipitation is not enough to refill the state’s depleted groundwater basins,” the report states.

In fact, officials said it would take at least five consecutive years of above-average water years, like 2023, to fill that gap.

But that goal is likely out of reach unless more is done to recover that underground water storage.

“California needs to replenish what nature provides by expanding groundwater recharge projects, upgrading water infrastructure, and modernizing our water distribution system … to be able to move water during high flows to maximize storage,” DWR said in a news release.

Groundwater is a crucial part of the water equation for California. Nearly 85% of Californians depend on it for some portion of their water supply and extracting from the state’s aquifers is critical when surface water supplies are lacking due to drought and lack of rainfall.

In addition to households, farms and businesses, the state’s ecosystem is heavily dependent on groundwater to sustain plant life and animal communities.

Paul Gosselin, DWR Deputy Director of Sustainable Water Management, said California is invested in “preparing for weather extremes” by making full use of wet years to store as much water as possible in preparation for inevitable dry years.

“The impressive recharge numbers in 2023 are the result of hard work by the local agencies combined with dedicated efforts from the state, but we must do more to be prepared to capture and store water when the wet years come,” Gosselin said.

To read more about the ongoing infrastructure upgrades and developments that state is making to capture and replenish its water reserves, click here .

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