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What is groundwater and why are we talking about it?

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. During an average year, California’s 515 alluvial groundwater basins and subbasins contribute approximately 38 percent toward the State’s total water supply. During dry years, groundwater contributes up to 46 percent (or more) of the statewide annual supply, and 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.

What is the Sustainable Groundwater Management Act (SGMA)?

On September 16, 2014, Governor Jerry Brown signed into law a three-bill legislative package, collectively known as the Sustainable Groundwater Management Act (SGMA). For the first time in its history, California has a framework for sustainable, groundwater management – “management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results.”

SGMA requires governments and water agencies of high and medium priority basins to halt overdraft and bring groundwater basins into balanced levels of pumping and recharge. The two Subbasins that Sloughhouse RCD is doing work in (the Cosumnes Subbasin and the South American Subbasin) are both medium priority subbasins. Under SGMA, we should reach sustainability within 20 years of implementing our sustainability plan, which must be submitted to the Department of Water Resources in January, 2022.

SGMA empowers local agencies to form Groundwater Sustainability Agencies (GSAs) to manage basins sustainably and requires those GSAs to adopt Groundwater Sustainability Plans (GSPs) for crucial groundwater basins in California.


Cosumnes Subbasin

In the Cosumnes Subbasin there are 7 GSAs: Sloughhouse Resource Conservation District, Clay Irrigation DistrictGalt Irrigation DistrictOmochumne Hartnell Water DistrictAmador County Groundwater Management AuthoritySacramento County, and the City of Galt. These organizations formed the Cosumnes Groundwater Authority to implement the Cosumnes Subbasin GSP. For more information on the Cosumnes Groundwater Authority CLICK HERE.

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South American Subbasin

In the South American Subbasin there are 5 GSAs: Sloughhouse Resource Conservation District, Omochumne Hartnell Water District, Sacramento CountySacramento Central Groundwater Authority, and the North Delta GSA. These organizations meet as the South American Subbasin Working Group and these meetings are open to the public and there are opportunities for public comment.

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Cosumnes Subbasin Groundwater Fee

On July 14, 2021, the Board of Directors of the Sloughhouse Resource Conservation District, acting as a groundwater sustainability agency in the Cosumnes Subbasin, held a public meeting and hearing at which a levy of a groundwater sustainability fee was considered and adopted. Follow the link on the right to learn more about the Groundwater Sustainability Fee.


Groundwater Resources

SGMA Basics

VIDEO: Understanding Groundwater, CA Dept. of Water Resources

BROCHURE: Sustainable Groundwater Management Act (CA Dept. of Water Resources)​BROCHURE: California’s Sustainable Groundwater Management Act (SGMA): Understanding the Law (CA Farm Bureau Federation)

WEBSITE: University of California, Division of Agriculture and Natural Resources

WEBSITE: Cosumnes Subbasin Working Group

WEBSITE: South American Subbasin Working Group


Resources for Domestic Well Owners

BROCHURE: Domestic Well Users and the Sustainable Groundwater Management Act (SGMA)PUBLICATION: A Guide for Domestic Well Owners


Conservation Resources

WEBSITE: Agricultural Water Use Efficiency

WEBSITE: Urban Water Use Efficiency



Water is scarce in California. But farmers have found ways to store it underground (October 5, 2021, NPR)

The Great California Water Grab (July 23, 2021, NPR)

Groundwater sub basin working to be held May 25, 2021 (May 21, 2021, Elk Grove Citizen)

Groundwater statues, plan discussed at meeting (March 31, 2021, The Galt Herald)

Galt meeting explains groundwater law impact (Nov. 1, 2017, The Galt Herald)