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The Stockton East Water District (SEWD) provides surface water for both agricultural and urban uses. By providing surface water for agricultural irrigation, the District supports San Joaquin County’s agricultural industry, which is the area’s leading economic activity. In 2022, San Joaquin County had a gross value of $3.2 billion worth of agricultural production, which is an increase of 1.6 percent from 2021. SEWD also supplies wholesale treated surface water, which is retailed to Stockton area customers by the California Water Service Company, the City of Stockton, and San Joaquin County.  Since 1978, the SEWD drinking water treatment plant has produced over one and a half million acre-feet of water for urban use; enough to cover the City of Stockton’s 65 square mile area over 37-feet deep in water.

Formation of the District

The Stockton East Water District, as currently structured, was formed in 1948 under the 1931 Water Conservation Act of the State of California. The District was originally organized as the Stockton and East San Joaquin Water Conservation District, an independent political subdivision of the state government. As such, SEWD was deemed responsible for acquiring a supplemental water supply and developing water use practices that would secure a balance between the District’s surface water and its customer’s groundwater supplies. Read the District Act. View the District Boundary Map.

District ActDistrict Boundary Map

Establishing Water Supply and Financial Structure

From 1948 to 1963, the District focused its efforts on water resource planning by evaluating groundwater conditions and determining requirements for supplemental water.  These intensive efforts by the District and other local agencies resulted in the construction of New Hogan Dam in 1964.  The District’s first supply of supplemental surface water was obtained through a contract with the United States Bureau of Reclamation (USBR), and a final agreement in 1970, which guaranteed 56.5% of New Hogan Reservoir’s yield to the District, was put in place between SEWD and the Calaveras County Water District (CCWD).

From its inception until 1962, the District’s basic financial structure was dependent upon property taxes. In 1963, the Governor of California signed a bill establishing the District’s right to levy groundwater use fees and surface water charges. The District used the additional revenue to contract for New Hogan water. About this time, SEWD began registering wells within the District, while check dams were built on the Calaveras River and Mormon and Mosher Sloughs to control surface irrigation water and promote groundwater recharge. The District also became actively involved in the pursuit of projects to mitigate significant groundwater issues, which included declining aquifer levels, pumping depressions under urban Stockton, and the continuing threat of saline intrusion in wells near the Delta.

Boundary Expansion and Drinking Water Treatment Plant Construction

In 1971, District boundaries were expanded to include the entire Stockton urban area, and plans were initiated for a 30 million gallon per day (MGD) drinking water treatment plant. In 1975, a District-wide election resulted in the approval of a $25 million bond to fund the new plant. The Dr. Joe Waidhofer drinking water treatment plant, located at 6767 East Main Street, was constructed in 1977 and began operation in 1978. In 1979, the Independent Benefit Commission concluded that the new drinking water treatment plant was a benefit to Stockton’s planning areas. Thereafter, SEWD assessed 14,000 acre-feet of additional agricultural acres, and, in 2005, annexed an additional 27,000 acres into the District. Today, SEWD’s area encompasses approximately 143,300 acres.

1955 Stockton Flood Scrapbook
Water Sources 

Pursuit of Supplemental Water Supplies

Since its inception, SEWD has actively sought supplemental surface water from the American River via the Folsom South Canal. The USBR directed the District to the Stanislaus River when they were applying for the water permits for New Melones Reservoir. Since the mid-1990’s, SEWD has been receiving surface water supplies from the Stanislaus River to supplement its Calaveras River supply. SEWD is currently attempting to secure the right to divert a portion of the flood flows from the Calaveras and Stanislaus Rivers, and all of the creeks in-between.  The goal of this pursuit is to provide the sources of water needed to fully address the overdrafted condition of the Eastern San Joaquin County (groundwater) Basin.

To date, environmental activists have prevented the construction of Auburn Dam on the American River and completion of the Folsom South Canal.  These same interests also forced the East Bay Municipal Utility District (EBMUD) to build a costly alternative to their right to American River water diverted into the Folsom South Canal.  This Freeport Regional Water Project was completed in 2010.  San Joaquin County continues to pursue a permit for a portion of the American River flows.  Conveying these flows into San Joaquin County could occur by wheeling through the Freeport Project or by completion of the Folsom South Canal.

In 1983, SEWD and Central San Joaquin Water Conservation District (CSJWCD) contracted with USBR for allocation of 75,000 and 80,000 acre-feet, respectively, from the New Melones reservoir.  This is known as the District’s Central Valley Project (CVP) contract.  That same year, SEWD expanded its surface water distribution system for irrigation water by constructing a 16,000 gallon-per-minute diversion from Calaveras River/Mormon Slough to Potter Creek.  Although the Calaveras River supply was more reliable in our early years, SEWD is confident the full allocation of our CVP contract for New Melones water will be more reliable over time.  Under current USBR operation of New Melones, SEWD and CSJWCD are provided up to 155,000 acre-feet of water from New Melones annually.

OID/SSJID Water Transfer Agreement

In 1997, SEWD entered into a water transfer agreement with Oakdale Irrigation District and South San Joaquin Irrigation District (OID/SSJID). This agreement allocates 8,000 to 30,000 acre-feet annually, based on New Melones storage and inflow as of April 1 of each year. The contract period for the allocation ended in 2009. This Agreement and shared ownership of Goodwin Dam have led to many opportunities for cooperative efforts to protect water rights and contracts of the Stanislaus River.

Managing the Calaveras Resource

In March 1998, the National Marine Fisheries Service (NMFS) listed the Central Valley steelhead as a threatened species, or Evolutionarily Significant Unit (ESU), under the Endangered Species Act.  In March 2000, NMFS designated the Calaveras River and Mormon Slough as critical Central Valley steelhead habitats.  Any actions that might harm the ESU or its habitat are restricted. Because this brought the entire management of the Calaveras River under review, SEWD immediately entered into an informal pre-consultation with federal and state regulators to begin discussing possible changes in the operation of New Hogan Dam and the Calaveras water supply system.

SEWD began work with their fishery scientists and NMFS to develop a plan to manage resident rainbow and steelhead trout in the Calaveras River.  This plan is called a Habitat Conservation Plan (HCP) and will provide SEWD and its water users with legal permission to continue using the water resources of the Calaveras River for agricultural, municipal, and industrial purposes.  In September 2020, the National Oceanic and Atmospheric Administration (NOAA) Fisheries approved the final HCP providing long-term security for crucial water operations through 2070. More information regarding the HCP can be found on the District’s dedicated HCP page.

SEWD also supports projects funded by the CALFED Bay-Delta Program and the U.S. Fish and Wildlife Service to help learn more about rainbow and steelhead trout in the river.  In 2005, SEWD concluded a CALFED Bay-Delta funded study to evaluate fish screen alternatives for water diversions on the Calaveras River. At the request of SEWD, the California Department of Water Resources (DWR) continues to study ways to improve fish passage in Mormon Slough.  Two fish passage improvement projects were completed in Mormon Slough; the Budiselich Dam project in 2012 and the Caprini Crossing project in 2013. While the ESA hurdles threaten the Calaveras River water supply for all users, SEWD is dedicated to creating a balance between environmental and water supply needs.

Growndwater Management 

The Farmington Project

In 2001, SEWD completed the Farmington Groundwater Recharge and Seasonal Habitat Study (Farmington Study) in conjunction with the United States Army Corps of Engineers and other local agencies. The Farmington Study identified areas suitable for recharge and seasonal habitat development, evaluated recharge techniques, conducted pilot recharge tests, developed a final report and recharge guide, and recommended an implementation strategy for the phased Farmington Program.

In 2003, the District completed the Pilot Phase of the Farmington Program, which consists of 60 acres of recharge ponds and fields adjacent to the Dr. Joe Waidhofer Drinking Water Treatment Plant. This project was awarded the American Society of Civil Engineers Water/Environmental Project of the Year in 2003 and the San Joaquin Council of Government Regional Excellence award in 2004.  The Demonstration Phase, which began in 2003, will investigate and construct up to 1,200 acres of recharge ponds and fields.  To date, over 13 sites have been investigated and two sites are moving forward to a demonstration study.  In 2006, construction began on another 30-acre recharge site at the drinking water treatment plant. The District estimates a recharge rate of 0.5 feet per day for this site.  For more information on the Farmington Program, see the Farmington Groundwater Recharge Site links at

Adoption of AB 3030 Groundwater Management Plan

SEWD adopted a Groundwater Management Plan in accordance with Assembly Bill 3030 (AB3030).  The goal of the SEWD AB 3030 Groundwater Management Plan is to continue the District’s efforts to protect existing water supplies, to relieve pressure on the groundwater basin by seeking supplemental surface water supplies for conjunctive use, and to maintain pressure on USBR to meet the contracted delivery amounts for New Melones water.  In 2006, the District adopted a Groundwater Management Plan pursuant to Senate Bill 1938 (SB 1938).  The Northeastern San Joaquin County Groundwater Banking Authority (GBA) facilitated adoption of this plan, which is required as a prerequisite for Proposition 50 grant funding. Link to the GBA: Eastern San Joaquin Groundwater Basin Groundwater Management Plan

Water Treatment 

Plant Expansion and New Melones Conveyance Construction

In 1991, the SEWD drinking water treatment plant was expanded to 40 MGD to accommodate increased demand from Stockton’s urban areas.  Construction on the New Melones Conveyance System, in anticipation of a new water supply, was completed in 1994; however, under the Central Valley Project Improvement Act (CVPIA), USBR did not supply water for the project in 1993 & 1994.  In 1995, SEWD began receiving New Melones water, but the amount received was less than the contracted amount. Legal action in this matter concluded with the award of damages to the District, and the granting of permanent contractor status by the USBR in 2012.

Peters Pipeline Project
In 2003, SEWD applied for and received a Proposition 13 Groundwater Recharge Storage Construction Grant for the Peters Pipeline portion of the Farmington Program. This conjunctive use project consists of a six-mile long, 60-inch diameter pipeline, which will provide water for agricultural irrigation, groundwater recharge, and drinking water treatment.  In dry years, well water resulting from wet year recharge will be pumped into the pipeline for use in the Stockton urban area.  Construction on the Peters Pipeline began in April 2005 and water deliveries began in the summer of 2006.

Efficiency Enhancement Project
In September 2005, construction began on the District’s $13 million Efficiency Enhancement Project, which expanded the DJWWTP treatment capacity to 62 MGD.  Enhancements included the construction of two new sedimentation basins, backup generators, and chemical feed system.  Efficiency improvements included upgrades the high service pump station, low lift pump station, the electrical system, and the SCADA system. This project was completed in 2007.

10 MG Finished Water Reservoir Project
In September 2012, construction began on a new 10MG finished water reservoir, which was completed in October 2013. This allowed the rehabilitation of the existing 35-year old 10MG finished water reservoir in 2014. Both reservoir projects were funded with 0% interest loans from the State Revolving Fund (SRF).

SEWD is an active member agency of Agricultural Water Management Council, American Water Works Association, Association of California Water Agencies, California Farm Water Coalition, California Special Districts Association, Central Valley Project Water Association, Central Valley Salinity Alternatives for Long-Term Sustainability (Lower San Joaquin River Committee), Northeastern Groundwater Banking Authority, Greater Stockton Chamber of Commerce, San Joaquin Council of Governments, San Joaquin County Farm Bureau Federation and the Water Education Foundation.