Lake Oroville Update - May 1, 2026

DWR Modifies its Invasive Mussel Inspection Program at Oroville

The California Department of Water Resources (DWR) has modified its inspection program for invasive mussels at Lake Oroville, the Thermalito Forebay, and the Thermalito Afterbay. Effective April 29, watercraft inspections, decontamination services, and seal checking at the Oroville facilities are no longer required. Blue Oroville seals are no longer required to launch watercraft and owners have permission to remove seals themselves, as inspectors will no longer be stationed at launch ramps. DWR will also reopen facilities that were closed to trailered launching including those at the Thermalito Forebay and Thermalito Afterbay. At locations requiring the removal of physical barriers, additional time will be required for crews to fully reopen facilities. Launching access at Lake Oroville will once again be available 24 hours a day, every day.

The decision to implement an invasive mussel boat inspection program at DWR's Oroville facilities in May 2025 was based on available information about how best to protect DWR infrastructure from golden mussel establishment. While DWR does not control many of the lakes and reservoirs upstream of Lake Oroville, it quickly established a program to reduce the potential risk of invasive mussel introduction through recreational boating. Additional analyses of golden mussel biology and habitat requirements, as well as an assessment of DWR's Oroville infrastructure, have shown a lower risk of golden mussel establishment than was originally anticipated.

During the last year, DWR performed a vulnerability review of Lake Oroville, the Upper Feather River Lakes, the Feather River Fish Hatchery, and Oroville-Thermalito Complex infrastructure to golden mussel colonization. The seasonal water temperature conditions at Lake Oroville and the Upper Feather River Lakes were evaluated based on a 2017 study in which researchers assessed the conditions golden mussels need to survive and reproduce.

For golden mussel maturation and reproduction to occur, water temperatures greater than 61.7°F for about 150 days are necessary for successful spawning and the formation of veligers, the larval stage of mussels. For veligers to complete their development and settle into a hard-shell mussel, water temperatures must be nearly 70°F for approximately 70 days.

Temperature thresholds for golden mussel maturation exist within the top 60 feet of Lake Oroville, meaning that sustained mussel populations would be confined to specific areas of the reservoir, such as floating infrastructure, and boats that remain on the water for lengthy periods. Mussels could survive in shallow shoreline locations until lake levels drop, at which point they would dry out and die. Extended cold water temperatures in the Upper Feather River lakes, the depth of Lake Oroville, and the continuous cold water releases from Oroville Dam to support salmon habitat are limiting factors for golden mussel spawning and larval development. Any veligers that are transported through the dam at lower lake elevation temperatures would be unlikely to survive, would have a difficult time growing, and would not have a significant impact on the Feather River Fish Hatchery and Oroville-Thermalito Complex powerplants.

Given this analysis of potential impacts to State Water Project infrastructure, DWR is no longer requiring watercraft inspections at Oroville. Ongoing water testing and visual inspections of infrastructure for invasive mussels will continue. Golden mussels have not been detected at DWR's Oroville facilities or the Upper Feather River lakes. Program changes are being coordinated with local recreation partners at the California Department of Parks and Recreation and the California Department of Fish and Wildlife.

DWR continues to partner with federal, State, and local agencies to mitigate golden mussel colonization throughout California's water systems. This includes coordinating with partners on a statewide reporting system for watercraft, continuing public education campaigns about golden mussels and how they spread, ongoing studies about effective treatment options, and implementing a variety of mitigation and maintenance actions to maintain State Water Project operations that are currently affected by the presence of golden mussels.

When recreating on California's waterways, always remember to:

• Clean aquatic plants and animal material from your boat, trailer, and equipment before leaving the ramp or parking lot.
• Drain ballast, bilge, livewells, and other water-containing devices, and never drain back into the waterway.
• Dry equipment, including bilge, ballast tanks, and livewells, before launching into another body of water.

More details about DWR's invasive mussel inspection program are available at water.ca.gov/mussels.

DWR Conserving Water at Lake Oroville

During the winter and early spring months, flood control releases from Oroville Dam ensure the safety of the City of Oroville and downstream communities by reserving storage space to capture high storm inflows while permitting controlled and coordinated releases from the dam. As the warm summer months approach and rain and snowstorms driven by atmospheric rivers wane, DWR transitions from making flood control releases at Oroville Dam to conserving as much water in the reservoir as possible, while still meeting water delivery and environmental requirements. Given the largely dry conditions and low snowpack in the Feather River watershed, DWR has flexibility to conserve water and encroach into the flood space and has received approval from the U.S. Army Corps of Engineers (USACE) for the current release schedule.

DWR has decreased total releases from Lake Oroville to account for reduced inflows into the reservoir while optimizing storage for the benefit of water supply, recreation, and fish and wildlife enhancement. DWR coordinates releases closely with USACE and other water operators and adjusts releases as needed to maintain balance throughout the water system.

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

• Current Oroville Reservoir Level: 893 feet elevation
• Current Storage: 97 percent of capacity
• Total Releases to the Feather River: 1,700 cubic feet per second (cfs); reducing to 1,300 cfs on Sunday, May 3

Lake Oroville is the largest storage facility in the State Water Project, providing flood protection while supporting environmental and water delivery needs for 27 million Californians. Some water released from Oroville for flood control is captured downstream for beneficial uses by local landowners, communities, and the State Water Project. Releases from Oroville Dam also support Feather River habitat for salmon, steelhead, sturgeon, and other river species. DWR continues to monitor lake levels, weather forecasts, and mountain snow levels to optimize water storage and allow for carryover storage into the following year.

Hours Extended for Spillway Day-Use Area

The Spillway Boat Ramp and Day Use Area is now open from 5 a.m. to 11 p.m. to accommodate extended daylight hours as summer approaches. All vehicles and trailers are subject to inspection by the California Highway Patrol (CHP) for security purposes. There are five other boat ramps at Lake Oroville that are open 24 hours a day and do not require CHP inspections: Bidwell Canyon, Loafer Point, Loafer Creek, Lime Saddle, and Enterprise.

Clay Pit SVRA Visitor Appreciation Day

Join the California Department of Parks and Recreation (State Parks) at the Clay Pit State Vehicular Recreation Area (SVRA) for Visitor Appreciation Day on Saturday, May 2 from 10 a.m. to 2 p.m. The event will feature exhibitors, off-highway vehicle demonstrations, and a food truck. This is a free, family-friendly event to show appreciation for the park's community. Note - the event will be canceled if it rains.

Located at 4900 Larkin Road, Oroville, CA 95965, the Clay Pit SVRA is open daily from 8 a.m. to sunset. The SVRA is a 220-acre facility that provides a fenced open riding area for motorcycles, all-terrain vehicles, and 4x4 recreationists. Clay mined from this area was used in the construction of Oroville Dam in the 1960s. What remains is a large, shallow depression surrounded by low hills that forms a prime location for off-highway vehicle recreation.

Feather Fiesta Days

For more than 70 years, Feather Fiesta Days has been Oroville's premier hometown celebration. Festivities are held over two weekends - Saturday, May 2 through Saturday, May 9 with a large variety of activities. Get the party started with a Chili Cook-Off, followed by the Kiwanis Kiddies Day Parade, and Feather River Recreation & Park District's Concert in the Park. Then head to downtown Oroville on Saturday, May 9 for the Gold Rush Car Show, Feather Fiesta Days Parade, craft fair, and vendor and food booths.

Stop by DWR's booth in downtown Oroville between 10 a.m. and 4 p.m. on Saturday, May 9. DWR will share information about Lake Oroville recreation areas and offer a craft activity and community art project. Create Feather River-inspired tissue paper stained glass art or help decorate a tissue paper banner mural. Staff will display your beautiful banner artwork at the Lake Oroville Visitor Center for the next few weeks.

Learn more about scheduled Feather Fiesta Days activities at visitoroville.com.

Feather River Fish Monitoring Station

DWR resumed operations of the Feather River fish monitoring station on March 4, 2026 to capture the return of spring-run Chinook salmon. Monitoring was temporarily suspended at the end of December 2025 due to anticipated high flows in the Feather River. Upstream migrating fish totals between March 4 and April 27, 2026 are:

• Spring-run Chinook salmon: 1,412
• Steelhead: -21 (most likely kelts moving downstream)
• To see previous year data, visit CalFish.org.

Current Lake Operations

Lake Oroville is at 893 feet elevation and storage is approximately 3.32 million acre-feet (MAF), which is 97 percent of its total capacity and 121 percent of the historical average.

Feather River flows are at 650 cfs through the City of Oroville with releases from the Thermalito Afterbay River Outlet at 1,050 cfs for a total Feather River release of 1,700 cfs downstream. Releases from the Outlet will reduce to 650 cfs on May 3 for a total Feather River release of 1,300. 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 11:59 p.m. on 4/30/2026.