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Resources for Groundwater Sustainability in the Delta-Mendota Subbasin

An Essential Hub for 21 Groundwater Sustainability Agencies (GSAs)

Our website serves as a shared resource dedicated to all 21 Groundwater Sustainability Agencies (GSAs) operating within the Delta-Mendota Subbasin. Here, you will find vital information about activities, meetings, and resources related to the sustainable management of our groundwater resources.

Delta-Mendota Subbasin Groundwater Sustainability Plan (GSP)

In July, 2024, the 21 GSAs of the Delta-Mendota Subbasin adopted a single GSP, which will guide management decisions to meet groundwater sustainability goals under the Sustainable Groundwater Management Act (SGMA). The chapters of the single GSP are below:

Central Delta-Mendota GSA Policies

In 2021, legal counsel developed the Central Delta-Mendota GSA (CDMGSA) Well Census and Registration Policy, and the Well Metering and Reporting Policy to support implementation of the Groundwater Sustainability Plan (GSP).
On March 26, 2026, legal counsel presented updated policies to reflect the coordination of the Delta-Mendota GSAs under the single GSP approved in 2024. There were no substantive changes to the policy made, and the CDMGSA Board approved the policies presented.
Well Census and Registration Policy
The Well Census and Registration Policy requires new wells to be registered within 30 days. Please fill out well registration forms here.
Well Metering and Reporting Policy
The Well Metering and Reporting Policy requires that wells are metered and that monthly reported data is available to the CDMGSA for annual reporting requirements. Please fill out the well meter registration and pumping forms here. On August 27, 2026, the CDMGSA Board approved the Miscellaneous Fee Schedule to impose penalty fees on well owners who fail to register or meter their wells. If you are a well owner with an inactive well and would like to petition the Board for an exemption from the well metering requirement, please fill out the Inactive Well Metering Exemption Form and submit to administration@cdm-gsa.com.
Surface Water Prioritization Policy
The Surface Water Prioritization Policy outlines methods to reduce demand on groundwater in the CDMGSA region by prioritizing surface water use where possible.
Central Delta-Mendota GSA Eagle Field WD-Fresno County-Fresno Slough WD-Merced County-Mercy Springs WD-Oro Loma WD-Pacheco WD-Panoche WD-San Luis WD-Santa Nella County WD-Tranquillity ID-Widren WD
Contacts
ADMINISTRATION@CDM-GSA.COM
12931 State Highway 33 Santa Nella CA 95322-9759 US
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