Roseville recharged groundwater basin with water volumes equivalent to 32 Olympic-sized pools last week

Updated January 10, 2022
Roseville recharged groundwater basin with water volumes equivalent to 32 Olympic-sized pools last week

With a significant amount of rainfall to close 2021, Folsom Reservoir gained a substantial amount of water in a short period. During the winter months especially, federal water managers who operate Folsom Reservoir are often confronted with complex decisions about when and where water is released from federally-operated reservoirs for winter flood protection, environmental flows, and water needs throughout the year. This is the case to start 2022.

Because of the City’s investments in groundwater management and technologically advanced water infrastructure, Roseville can replenish and extract water from aquifers underground.

We began capturing surplus water from Folsom Reservoir last week through our contract with the U.S. Bureau of Reclamation Central Valley Project to store within these aquifers through specially designed wells. We will extract this stored water during future dry periods when the City needs additional water supply.

Instead of allowing this water to spill out to the Pacific Ocean, we took an initial delivery of 65-acre feet City (about 22 million gallons) to replenish the aquifer beneath the City. To put into context, one acre-foot is enough water to supply a home with a family of four annually.

“We’ve been installing groundwater wells to do both replenishment and extraction for more than a decade. Back in 2019, we replenished the basin with 952-acre-feet of water,” said Sean Bigley, assistant director of water for Roseville. “The water we banked was used last year to reduce reliance on Folsom Reservoir and to protect the Lower American River during the peak summer month’s drought impacts.”

Using Folsom Reservoir water to replenish the groundwater basin provides multiple benefits, including:

  • Capturing water that would have been unnecessarily spilled to the ocean
  • Banking water in “underground reservoirs”— like a savings account— to use in a coordinated fashion depending on water conditions and alleviating surface water supplies when surface water is scarce
  • Actively replenishing to ensure a healthy groundwater basin as required by state law and as a good steward of our water resources

Roseville anticipates the availability of more surface water for replenishment over the coming weeks, but it depends on the need to create additional winter flood capacity at Folsom Reservoir.

The idea of using this water is consistent with regional plans to use both surface water and groundwater interchangeably for local usage to maintain high water reliability.

For more information about Roseville’s groundwater program, visit or visit to learn more about Roseville’s water resource planning.

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