Groundwater is an important source of water stored in the earth beneath our feet, in spaces between sand, soils, and fractured rock known as an aquifer. Layers of aquifers make up a groundwater basin. California’s 515 alluvial groundwater subbasins contribute approximately 40% of the State’s total water in wet years and up to 60% during dry years. Groundwater serves as a critical buffer against the impacts of drought and climate change. Many municipal, agricultural, and disadvantaged communities rely on groundwater for up to 100 percent of their water supply needs.
We mostly access groundwater through wells and pumps, and it is a crucial buffer against drought when surface water levels, like that inlakes and reservoirs, are running low. When groundwater is extracted in excess of what nature or manmade recharge efforts can replenish, groundwater elevations drop.
Learn More About Groundwater
- The Groundwater Project: Groundwater Learning for Everyone Everywhere
- California Dry Well Reporting System
- California Farm Bureau Federation: Understanding SGMA
- The Nature Conservancy: Groundwater Resource Hub
Groundwater in the News
- “California’s drought has caused entire towns to sink nearly a foot in just one year. This map shows where” – SF Chronicle (May 2022)
- “More Heat, More Drought: New Analyses Offer Grim Outlook for the U.S. West.” – Yale Environment 360 (May 2022)
- “Water is scarce in California. But farmers have found ways to store it underground” – NPR (October 2021)
- “Area groundwater subject of workshop” – The Galt Herald (September 2021)
- “The Great California Water Grab” – NPR (July 2021)
- “Groundwater subbasin workshop to be held May 25” – Elk Grove Citizen (March 2021)
- “Groundwater status, plan discussed at meeting” – The Galt Herald (March 2021)
- “Galt meeting explains groundwater law impact” – The Galt Herald (November 2017)