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Delta-Mendota Subbasin

Sustainable Groundwater Management 


Welcome to the Delta-Mendota Subbasin Sustainable Groundwater Management website, a shared resource for all 23 Groundwater Sustainability Agencies (GSAs) in the Delta-Mendota Subbasin. This website is dedicated to providing information on activities, meetings and resources related to the sustainable management of the Delta-Mendota Subbasin.

Delta-Mendota Subbasin

This website provides information on sustainable groundwater management activities, meetings and resources in the Delta-Mendota Subbasin. The Sustainable Groundwater Management Act, passed in 2014, requires the formation of local Groundwater Sustainability Agencies (GSAs) to oversee the development and implementation of Groundwater Sustainability Plans (GSPs), with the ultimate goal of achieving sustainable management of the state’s groundwater basins. As of June 2017, 23 GSAs have formed in the Delta-Mendota Subbasin. These GSAs have until January 31, 2020 to develop and adopt one or more GSPs for the Delta-Mendota Subbasin.

This website will provide updates on preparation of the GSP(s) for the Delta-Mendota Subbasin, as well as meeting announcements and availability of draft plans, maps and other relevant documents.

Quick Facts

Groundwater Basin Number: 5-22.07
County: Stanislaus, Merced, Madera, Fresno
Surface Area: 747,000 acres (1,170 square miles)

The Delta-Mendota Subbasin is bounded on the west by sediments of the Coast Ranges, and on the north by the Stanislaus/San Joaquin county line. The eastern boundary follows the San Joaquin River to Township 11 S, where it jogs eastward and follows the eastern boundary of Columbia Canal company to the San Joaquin River, then follows the Chowchilla Bypass and the eastern border of Farmer's Water District. It then trends southerly through Township 14S Range 15E on the eastern side of Fresno Slough, then follows the Tranquillity Irrigation District boundary to its southern extremity. Heading northward, it follows the eastern, northern, and northwestern boundary of San Joaquin Valley – Westside Groundwater Subbasin (corresponding with Westlands Water District boundaries).
The Delta-Mendota Subbasin is designated a high priority basin by the California Department of Water Resource’s (DWR) CASGEM program.

The Delta-Mendota Subbasin is designated a high priority basin by the California Department of Water Resource’s (DWR) CASGEM program.

Delta-Mendota subbasin map

Groundwater Management Plan

The San Luis & Delta-Mendota Water Authority developed a groundwater management plan (also known as a AB 3030 plan) for the northern agencies in the Delta-Mendota Canal Service Area in 1997. In 2011, the plan was updated to respond to new State legislation. Click here [link to pdf] for the 2011 Groundwater Management Plan.

GSAs in the Delta-Mendota Subbasin

As of June 2017, there are 23 Groundwater Sustainability Agencies (GSAs) the Delta-Mendota Subbasin that have submitted formation notices with DWR:

Aliso Water District

Central Delta-Mendota Region Multi-Agency

City of Dos Palos

City of Firebaugh

City of Gustine

City of Los Banos

City of Mendota

City of Newman

City of Patterson

County of Madera—3


Farmers Water District

Fresno County—Management Area ‘A’

Fresno County—Management Area ‘B’

Grassland Water District

Merced County—Delta-Mendota

Northwestern Delta-Mendota

Ora Loma Water District

Patterson Irrigation District

San Joaquin County—Delta-Mendota

San Joaquin County—Tracy

San Joaquin River Exchange Contractors Water Authority

Turner Island Water District-2 

West Stanislaus Irrigation District—1

West Stanislaus Irrigation District—2

Widren Water District

Public Outreach & Engagement

As part of developing the Groundwater Sustainability Plan, the Groundwater Sustainability Agencies will inform and involve interested and affected individuals and organizations (stakeholders) and the general public. 

This website will be updated as information becomes available.