Lake Oroville Update - March 21, 2025

Flood Control Releases from Lake Oroville Ongoing

The Department of Water Resources (DWR) continues federally required flood control releases from Lake Oroville to maintain flood protection for downstream communities. Water is being released through the Hyatt Powerplant for energy production and from Oroville Dam’s main spillway. With wetter watershed conditions earlier in the week, DWR increased releases to 15,000 cubic feet per second (cfs), but reduced releases today as drier conditions returned. DWR continues to conserve as much water supply as possible in coordination with the U.S. Army Corps of Engineers (USACE). Releases are subject to change based on ongoing weather conditions.

 

Between October and June, DWR is required to operate Lake Oroville for flood control under federal Water Control Manual guidelines set by USACE. These federal regulations establish a set storage space that is reserved to capture inflows from rain and future snowmelt, while protecting downstream communities from damaging flood events through water releases. Releases to the Feather River are coordinated closely with USACE and other downstream water operators.

 

Current reservoir levels are as follows, though estimates may change quickly:

• Current Oroville Reservoir Level: 868 feet elevation
• Current Storage Capacity: 86 percent
• Total Releases to the Feather River: 12,500 cfs; reducing to 11,500 cfs on Sunday

 

Lake Oroville is the largest storage facility in the State Water Project, providing flood protection while supporting environmental and water delivery needs to 27 million Californians. Some water released from Lake Oroville is distributed locally for agriculture benefits, while the remaining Feather River releases flow south through the State Water Project system to reduce salinity effects in the Delta, provide irrigation for crops in the Central Valley, and eventually make their way to Southern California. DWR continues to monitor lake levels, weather forecasts, and mountain snow levels to optimize water storage while allowing for carryover storage into next year.

 

Planned Water Fluctuations at the Oroville-Thermalito Complex

Water levels at several locations within the Oroville-Thermalito Complex will fluctuate this weekend for planned concrete work on the River Valve Outlet System (RVOS) at Oroville Dam. Starting today, March 21, water levels at the Thermalito Afterbay will drop approximately 3 feet, while water levels at the Diversion Pool and Thermalito Forebay will be approximately 1 foot lower than usual. These water level fluctuations are within the standard operating range at these facilities, with water elevations returning to their usual level by Sunday evening.

 

The lower water levels within the complex enable DWR to continue making progress on the RVOS at Oroville Dam. The system is a series of two parallel outlet conduits, each with two valves, that have the capacity to draw water from deep in Lake Oroville for release. The RVOS is a critical feature of the dam, providing the ability to discharge cold water to the Feather River to maintain water temperatures necessary for fish health. It also ensures the ability to maintain Feather River flows through RVOS releases during drought years, especially if reservoir levels drop below Hyatt Powerplant’s water intake structures.

 

Eagle Lake Trout Stocking

The California Department of Fish and Wildlife (CDFW) planted approximately 25,000 Eagle Lake Rainbow Trout at Lake Oroville today to support recreational fishing. Approximately 18,400 trout were planted at Loafer Creek and approximately 6,600 trout were planted at Lime Saddle. The trout were supplied by the Darrah Springs Hatchery and are about 10 to 12-inches in size, sterile, and are native to Eagle Lake in Lassen County. More information about Eagle Lake Rainbow Trout is available on CDFW’s website.

 

Christmas Tree Fish Habitat

DWR, the California Conservation Corps (CCC), and CDFW installed fish habitat structures earlier this month at Lake Oroville and the Thermalito Afterbay using approximately 1,300 recycled Christmas trees. The trees were collected by Chico Boy Scout Troop 2 and delivered free of charge to DWR by Recology, a local waste management company.

 

To create the habitats on Lake Oroville and the Thermalito Afterbay, members of the CCC team bundle the recycled Christmas trees together and anchor them in various locations around the lakebed. At Lake Oroville near the Bidwell Saddle Dam area, 744 trees were assembled into 35 structures. At the Thermalito Afterbay, 570 trees were assembled into 56 structures. Anchoring the trees allows them to remain submerged, providing juvenile fish safe refuge, and improving fisheries and recreational fishing opportunities.

 

For more than 30 years, DWR has worked with local groups to construct fish habitat structures, which is one of the longest continuously running warmwater fish habitat improvement programs in the State of California.

 

Forecast-Informed Reservoir Operations at Lake Oroville Can Increase Region’s Resilience to Floods

A new report released last week shows that changes to reservoir operations at Lake Oroville and New Bullards Bar Reservoir can further reduce flood risk for communities along the Yuba and Feather rivers during extreme atmospheric river storm events and potentially benefit water supply during drier periods. The approach, known as Forecast-Informed Reservoir Operations, or FIRO, uses improved monitoring, weather, and runoff projections to build more flexibility and efficiency into reservoir operations.

 

In the largest FIRO assessment to date, DWR and Yuba Water Agency (Yuba Water) partnered with the Center for Western Weather and Water Extremes (CW3E) at UC San Diego’s Scripps Institution of Oceanography and the U.S. Army Corps of Engineers’ (USACE) Engineering Research and Development Center to evaluate if FIRO could be implemented at both reservoirs to reduce downstream flood risk without negatively impacting water supplies. Lake Oroville is managed by DWR and New Bullards Bar is managed by Yuba Water.

 

Using historical forecasts, reservoir storage and river flow data, scientists found that FIRO, combined with a planned second spillway at New Bullards Bar, could provide additional flood storage capacity in the Yuba-Feather system and reduce downstream peak flows during prolonged storms like the 1986 and 1997 floods that devastated Yuba County.

 

“California’s reservoirs play a critical role in safeguarding our communities from floods and maintaining our state’s water supply, especially as we continue to see more extreme weather events in the form of larger, wetter, and more frequent storms and longer, more severe periods of drought,” said DWR’s State Climatologist Dr. Michael Anderson. “The Yuba-Feather FIRO Viability Assessment is an important step toward improving flood protection to communities downstream while managing California’s valuable water resources for decades to come.”

 

Learn more about the Yuba-Feather FIRO Final Viability Assessment in DWR’s news release.

 

Current Lake Operations

Lake Oroville is at 868 feet elevation and storage is approximately 2.96 million acre-feet (MAF), which is 86 percent of its total capacity and 123 percent of the historical average.

 

Feather River flows are at 4,000 cfs through the City of Oroville with 8,500 cfs being released from the Thermalito Afterbay River Outlet (Outlet) for a total Feather River release of 12,500 cfs downstream. On Sunday total Feather River flows will reduce to 11,500 cfs with flows through the City of Oroville at 3,000 cfs and flows from the Outlet at 8,500 cfs. DWR continues to assess Feather River releases daily. 

 

The public can track precipitation, snow, reservoir levels, and more at the California Data Exchange Center. The Lake Oroville gage station is identified as “ORO.”

 

All data as of midnight 3/20/2025.

 

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