Surface Water Integration Project



The City of Ceres (City) has historically relied entirely on groundwater from the Turlock Groundwater Subbasin as its primary drinking water source. Serving a population of approximately 48,000 residents, the current water supply is provided by 13 active groundwater wells and two storage tanks. In 2022 the City’s water division pumped more than 2 billion gallons of drinking water annually for its residential and commercial users, which averages 5.9 million gallons of water daily.

Groundwater contains contaminants that currently or will soon require treatment processes to remove these impurities prior to consumption. As groundwater quality standards become increasingly stringent, the cost for treatment and replacement wells will continue to increase. If the City were to rely solely on groundwater as the source for their drinking water, monthly costs to treat groundwater to current and future drinking water standards would increase dramatically. Groundwater is a limited resource that will not meet future demands and the State’s Sustainable Groundwater Management Act (SGMA) may mean that all cities will have to reduce dependence on groundwater.

As with many communities across California, the recent prolonged drought strained the City’s groundwater supply and intensified the need to invest in alternative, supplemental water sources. To build a more resilient water supply, the City of Ceres has diversified its water portfolio by partnering in the Stanislaus Regional Water Authority’s (SRWA) Regional Surface Water Supply Project to build a new water treatment plant and utilize a new surface water supply from the Tuolumne River.

Over the years, the City has investigated a number of alternatives to the Project. None of these options were considered as dependable, technically feasible, cost-effective, or as sustainable as a drinking water plant on the Tuolumne River.  As part of the Regional Surface Water Supply Project, Tuolumne River water will be treated at a new robust, state-of-the-art water treatment plant to meet and exceed all current federal and state drinking water standards. Unlike wells, the plant can be easily changed to comply with future changes in drinking water standards, as necessary.

As a result of the Regional Surface Water Supply Project, Ceres residents will continue to have clean and healthy drinking water for the future and will benefit from a more resilient water supply during times of drought. Long term benefits of the project include improved water quality and helping to replenish groundwater supplies. 

To learn more about the project, view the SRWA Website

Surface Water-Groundwater Integration

The City is leading the integration of the new surface water supply into its existing water distribution system. The City worked with a consultant to develop an Integration Plan that includes an evaluation of historical groundwater quality and future anticipated surface water quality. When introducing surface water to a groundwater dominant water distribution system, discolored water can occur in the distribution system for various reasons. This Plan offers recommended strategies for stabilizing and flushing the distribution system to avoid discolored water events.

Introducing a new water source into an existing distribution system can be challenging and must be carefully implemented. Ceres is working diligently to ensure that this new water source is integrated into its water supply with a minimal amount of water quality disruption. The City’s primary concern is minimizing the potential for discolored water occurrence by implementing the strategies recommended in the Integration Plan. Even the best implementation cannot prevent all discolored water events and customers should contact the City Public Works Department at (209) 538-5732 if they encounter any changes in the color of their tap water.

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