By Pauline Roccucci
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.
Basin receives 160 Olympic-sized pools worth of surface water
Because of the City’s investments in groundwater management and technologically advanced water infrastructure, Roseville can replenish and extract water from aquifers underground.
In early January, we began capturing surplus water from Folsom Reservoir through our contract with the U.S. Bureau of Reclamation Central Valley Project to store water 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 (about 21 million gallons) in early January to replenish the aquifer beneath the City. Since then, we added an additional 260-acre feet of water (about 85 million gallons.) This amount of water could fill 160 Olympic-sized pools.
Using surface water and groundwater interchangeably to ensure water reliability
“We’ve been installing groundwater wells to do both replenishment and extraction almost 20 years ago. Back in 2019 and early 2020, we replenished the basin with more than 1,000 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 scarce
- Actively replenishing to maintain 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, 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 water reliability.
Regional water use down 22 percent last November
In addition to using water conjunctively, the Sacramento‐area residents reduced their water use by 22 percent in November 2021 compared to the same month in 2020. November reductions are in addition to a 13 percent decrease in regional water use since the last drought. In Roseville, water use numbers reduced in November by nearly 28 percent and 13 percent in December compared to 2020 water usage.
More information about Roseville’s water supply use and plans
For more information about Roseville’s groundwater program, visit Roseville.ca.us/groundwater or visit Roseville.ca.us/waterfuture to learn more about Roseville’s water resource planning.
