Nick C. DeGroot Water Treatment Plant

Advanced Technology to Ensure Quality

The South San Joaquin Irrigation District (SSJID), in conjunction with the cities of Escalon, Lathrop, Manteca and Tracy, comprise the South County Water Supply Program.

This cooperative effort has been successful in addressing a common need. With cities relying heavily on groundwater, they became vulnerable to declining groundwater levels and increasing salinity of underground aquifers.


This regional water supply program has four goals:

    1. To protect and enhance the economic health of the region by providing reliable, safe supplemental water to cities.
    2. To use conserved surface water from SSJID to avoid adverse impacts to current agricultural customers.
    3. To meet local needs by keeping adequate water in the region.
    4. To reduce the area’s reliance on groundwater.

SSJID supplies the raw water and operates the treatment plant and transmission system, and participating cities pay for the raw water and reimburse the District for operating expenses. The sale of raw water provides a financial benefit to SSJID irrigation customers.

Coming together more than 20 years ago, SSJID and the cities were looking to balance agricultural and urban water needs. That required gaining public support and involvement.
The first water deliveries took place in June 2005. In July of that year, the South County Water Supply Program celebrated its momentous achievement by dedicating the plant to late SSJID Board Director Nick C. DeGroot. Currently delivering to Manteca, Tracy and Lathrop, the plant will ultimately connect to Escalon in Phase II of the project.

The plant is an impressive technological achievement. It operates under the Zenon 1000 Submerged Membrane System. Its multi-barrier treatment approach removes most particles from the treated water and further protects public health with a disinfection process. The water comes from SSJID’s Woodward Reservoir and is clarified through a dissolved air floatation process before moving into the membrane filtration system. The California Department of Health Services granted this process the highest rating for removal of giardia and cryptosporidium.

The Nick C. DeGroot Water Treatment Plant can process approximately 40 million gallons per day (MGD). In addition to 37 miles of pipeline, the transmission system features seven pump stations and four large storage tanks. The pump stations deliver water from the pipeline to the city water lines, while the storage tanks can hold 1 million gallons of water. During Phase II of the project, one pump station and an additional 3 million gallon tank will be added.

The Nick C. DeGroot Water Treatment Plant, provides water to about 200,000 residents of south San Joaquin County.