Sustainable Groundwater Management Act

What is SGMA?

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.

Stanislaus and Tuolumne Rivers Groundwater Basin Association

In 2017, member agencies of the Stanislaus and Tuolumne Rivers Groundwater Basin Association (STRGBA) - City of Modesto, Modesto Irrigation District, City of Oakdale, Oakdale Irrigation District, City of Riverbank, City of Waterford and Stanislaus County - formed as a Groundwater Sustainability Agency (GSA). STRGBA GSA has the authority and responsibility to manage the majority of the Modesto groundwater basin. The STRGBA coordinates its planning process with other neighboring water agencies as well as state agencies.

The Tuolumne County GSA is responsible for the small section of the Modesto Subbasin that falls within Tuolumne County. Many groundwater basins in the San Joaquin Valley have experienced heavy groundwater pumping - especially during the recent 2012-2016 drought. Several are now in a condition of critical overdraft. The Modesto basin isn’t considered to be critically overdrafted, but since most of the cities within our basin rely solely on groundwater, we’re considered a high-priority basin. Due to that designation, SGMA requires that we adopt and begin implementation of a GSP by January 31, 2022.

For more information about the Stanislaus and Tuolumne Rivers Groundwater Basin association visit the STRGBA website.

The Modesto Subbasin Groundwater Sustainability Plan Draft can be found here (links to an external site).

S T R G B A Webinar Full Flyer

Tuolumne County parcels that fall within the Modesto Subbasin:

Map of Tuolumne County parcels within Modesto Subbasin
GSA Modesto Subbasin Map REV1

Contact Us

  1. Kim MacFarlane

    Public Works Director

    Physical Address:

    A.N. Francisco Building
     48 Yaney Ave.
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     Sonora, CA 95370

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    Sonora, CA 95370

    Ph: 209-533-5601


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