Your WaterFlood and Stream ManagementWatershed and Environment

The Patterson Pass Water Treatment Plant Upgrades and Ozonation Project will improve treated water quality, replace aging equipment, increase treated water storage capacity, and increase plant production capacity from 12 million gallons of water a day to 24 million gallons a day (MGD). The project will add new ozonation facilities, replace the existing ultrafiltration (UF) membrane filters and existing three conventional filters with six new conventional filters, and add a new 5 million gallon (MG) treated water storage tank.

The following documents provide more information about the project:

Current Status:  The project is currently in the construction phase. The most recent quarterly progress report can be viewed below:

Construction Schedule:  Construction began in March 2019, and is anticipated to be complete in early 2022.

Project Cost:  The project is estimated to cost $110 million for planning, design, and contruction; and is funded by water rates, new connection fees, and bonds.

Contact Information:  If you have any questions or concerns about this project, please contact Mona Olmsted at (925) 454-5033, or by email at


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