Tuolumne County Groundwater Sustainability Agency (TCGSA)

In September 2014, Governor Jerry Brown signed the Sustainable Groundwater Management Act of 2014 (SGMA). SGMA sets the framework for statewide sustainable groundwater management by local agencies. SGMA requires, among other things, the formation of Groundwater Sustainability Agencies (GSA) and the preparation of Groundwater Sustainability Plans (GSP). Groundwater basins subject to SGMA must achieve sustainability within 20 years of implementing their GSP.

The Tuolumne County GSA is responsible for the small section (approximately 1,000 acres) of the Modesto Subbasin that falls within Tuolumne County.

A limited number of parcels along the western edge of Tuolumne County fall within the Modesto Subbasin of the San Joaquin Valley Basin and thus are subject to this mandate.   As a cost-savings measure, Tuolumne County has agreed with the other responsible jurisdictions in the Modesto subbasin to create a joint GSP, with the cost-sharing agreement for the first phase of the GSP approved by the Tuolumne County Board of Supervisors in 2018.   The Stanislaus and Tuolumne Rivers Groundwater Basin Association (STRGBA), is a Joint Powers Authority between Stanislaus County, the City of Modesto, the City of Oakdale, the City of Riverbank, the City of Waterford, Modesto Irrigation District, and Oakdale Irrigation District. The TCGSA continues to collaborate with STRGBA and its member agencies toward the completion of the shared GSP and its mandated updates.