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Regional Groundwater Storage and Recovery (WSIP)

Click to see the entire project map.

See the entire project map here.

Project Update
The Regional Groundwater Storage and Recovery (GSR) project includes the construction of up to 16 new recovery wells and facilities consisting of chemical treatment equipment, tanks, pumping systems, and associated pipelines. Twelve well sites are now under construction and drilling on the last well as part of the current construction contract started in October. The locations for the remaining well sites are under investigation. For regular construction updates, please visit our Peninsula Blog.

In January 2015, the SFPUC awarded this $42.9 million construction contract to Ranger Pipelines, Inc. and started construction in spring 2015 and anticipates completion in spring 2018.

                   Regional Groundwater Map
This project includes the installation of up to 16 new recovery well facilities in northern San Mateo County.


How Will the Project Work?
The concept of groundwater storage and recovery, also known as “conjunctive water management”, consists of storing water in wet years and recovering that water for use during dry years. As part of the GSR project, surface water will be used instead of groundwater in wet years, allowing the groundwater to recharge through rainfall and decreased pumping. This will create a savings account of up to 20 billion gallons of groundwater that will be stored in the aquifer. In dry years, when less surface water is available, the saved water will be pumped from the new groundwater well recovery facilities at a rate of up to 7.2 million gallons per day, which would serve up to 24,000 households. The GSR project is designed to help diversify our water supply for drought protection and will ensure we are even more resilient during and after an earthquake or other emergency. The water quality from this stored supply will meet the California Department of Public Health requirements for drinking water supplies.

In wet years, municipal pumping is decreased and groundwater fills the available aquifer storage space.
In dry years, groundwater is pumped from storage – the “water savings account”.


A Regional Approach to Drought Protection

California Water Service Company, City of Daly City, City of San Bruno and SFPUC celebrate signing of operating agreement.

A landmark agreement between the SFPUC and three San Mateo County organizations was finalized and signed in December 2014 to ensure long-term management and sustainability of the South Westside Groundwater Basin. The partnership with SFPUC, City of Daly City, City of San Bruno and California Water Service Company allows these agencies to operate the basin and provide a new 20 billion gallon regional dry year groundwater supply. These San Mateo County agencies provide drinking water from two sources, local groundwater from the South Westside Groundwater Basin and surface water supplies from the SFPUC.

Groundwater Storage Around the Bay
In the Bay Area alone, similar programs are being implemented by the Santa Clara Valley Water District (serving Campbell, Cupertino, Gilroy, Los Altos Hills, Milpitas, Monte Sereno, Morgan Hill, Mt. View, Palo Alto, San Jose, Santa Clara, Saratoga and Sunnyvale, and the towns of Los Altos and Los Gatos), the Alameda County Water District (serving Fremont, Newark, and Union City) and the Zone 7 Water Services Agency (serving Livermore, Pleasanton and Dublin). These programs have been operating successfully for decades.

Project Information

    April 2015
    March 2018
  • COST
    $114 Million

Additional Information

- North GSR Construction Fact Sheet

- South GSR Construction Fact Sheet

- Regional Groundwater Informational
  Fact Sheet

- Regional Groundwater Informational
  Fact Sheet; Spanish

- Regional Groundwater Informational
  Fact Sheet; Chinese

- 2014 Groundwater Monitoring Report

- Project Terms & Definitions

- Useful Links to Learn More About Groundwater


Need More Information?

Contact Us

24-hour answering service: 866.973.1476

Miranda Iglesias, Communications Liaison 
Phone: 415.551.4394