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Blog Post · June 27, 2024

Data Is Key to Protecting California’s Groundwater

photo - Closeup shot of an artichoke crop in California

This year marks the tenth anniversary of the Sustainable Groundwater Management Act (SGMA), the landmark 2014 legislation that regulates California’s groundwater use for the first time. It was a key turning point for a state that had overdrafted its aquifers for decades and was suffering the consequences. Implementing SGMA has been no simple feat, yet one surprising ally has emerged in the fight to restore California’s groundwater: data.

It’s no overstatement to say that before SGMA, groundwater management was a bit of a Wild West situation in most of California’s agricultural regions. Apart from county-level reporting, data about where crops were being grown was limited, and information about groundwater conditions was practically non-existent.

The legislature, local agencies, and the California Department of Water Resources (DWR) have all played key roles in transforming the data landscape. Things actually started to shift a few years prior to SGMA:

  • In 2009, the legislature called for a new state and local effort to track and report groundwater elevations.
  • In 2014, SGMA required local agencies to prepare groundwater sustainability plans (GSPs) detailing historic, current, and projected groundwater conditions and to provide annual updates on key metrics. This reporting, which began in 2020, necessitated significant investments in monitoring and measuring groundwater, which DWR supported.
  • Finally, a 2015 law required the public release of Well Completion Report data, which tracks long-term trends in well drilling across the state.
  • In addition to making all of this data available on its website, DWR has added some other important series to the mix, with the development of detailed annual statewide crop mapping, and the Dry Well Reporting System, where water users can report problems with their domestic wells.

Simply put, there’s a lot more information available about California’s water use and land use than there was ten years ago, and that’s paying big dividends. In our recent policy brief, “Drought and Groundwater Sustainability in California’s Farming Regions,” we were able to identify new trends that would have been invisible even five years earlier.

Here’s what the improved data showed us:

Surprisingly, perennial crops are still expanding their footprint. Perennial crops—including fruit and nut trees and vineyards—have long lifespans and tend to be relatively profitable, but they require irrigation throughout every spring and summer to maintain their health. (In contrast, it is less costly for farmers to temporarily take fields planted with annual crops out of production when water supplies are tight.) During the recent 2020–22 drought, annual crops saw cutbacks due to reduced water supplies, but perennials continued to expand their footprint, growing by nearly 260,000 acres between 2018 and 2022. Perennials now comprise half of irrigated cropland statewide, and more than 60% in the heavily overdrafted San Joaquin Valley, where future groundwater constraints could reduce cropland by over 500,000 acres by 2040. Most of the recent perennial acreage increases took place in this region, and such plantings may make it harder to meet future requirements to pump less. (For more information, see our dataset.)

Domestic wells are going dry in different places. Statewide, reports of dry domestic wells rose by about 30% in the latest drought compared to the peak years of the prior drought (2013–15). Although the number of dry wells in the San Joaquin Valley was similar in these two droughts, we saw many more well failures in the Sacramento Valley, which experienced particularly dry conditions between 2020–22. (For more information, see our dataset.)

Growers are drilling fewer irrigation wells. During droughts, farmers have historically drilled more wells to make up for surface water shortfalls, which risks causing undesirable impacts from additional pumping. But we may finally be seeing some good news on this front: newly drilled irrigation wells declined substantially between the 2013–15 and 2020–22 droughts, perhaps in part due to executive orders to limit well drilling near drinking water wells and in areas experiencing land subsidence.

Groundwater pumping and overdraft are better understood than ever before. In our recent brief, we used newly reported local data to compare pumping from the recent and past drought. We found that while pumping in the San Joaquin Valley during 2021–22 was similar to 2013–14, it was higher by about one-third in the Sacramento Valley, suggesting that while pumping may not be getting worse, it doesn’t appear to be improving much, either. This data allows groundwater managers to track how sustainability efforts are faring in something close to real time, which makes it possible to correct course on the path to sustainability sooner. (For more information, see DWR’s dataset.)

Investments from the state and local agencies have really moved the needle on data collection in the past ten years. Data gaps still exist, of course—but agencies have shown that they can make real change. As Californians work to manage groundwater, weather increasingly intense droughts, and support the state’s diverse agricultural economy, continuing improvements in data will make a world of difference.


agriculture groundwater groundwater sustainability Safe Drinking Water San Joaquin Valley SGMA Water Supply Water, Land & Air