Lake Oroville Update - May 9, 2025

Mussel Inspection Program Coming to DWR’s Oroville Facilities  

With the discovery of the highly invasive golden mussel in California waterways, the Department of Water Resources (DWR) is starting a mussel inspection program in Oroville to protect State Water Project (SWP) infrastructure. Mandatory watercraft inspections will be required prior to launching at the Oroville facilities (Lake Oroville, Thermalito Forebay, Thermalito Afterbay) and are anticipated to start ahead of the Memorial Day weekend. DWR is still finalizing details of its inspection program and is hiring staff to the prevent the introduction of this highly invasive species to these reservoirs.

DWR aims to maintain recreation opportunities at these facilities while protecting California’s water supply, power generation, ecosystem, and the Feather River Fish Hatchery. In advance of the inspection program beginning, DWR staff has begun placing concrete blocks around the Thermalito Afterbay to block access to unauthorized launch areas and to direct trailered launching to Monument Hill only.

Once the program begins, all trailered and motorized watercraft launching at DWR’s Oroville facilities will require a properly attached seal - a wire with a blue-colored tag specific to the Oroville Facilities that connects the watercraft to the trailer or, in the case of a jet ski, seals the steering unit to the back of the vessel. Once the seal is connected, it cannot be removed without cutting the wire so mussel prevention staff will know that the watercraft has not been launched since being sealed. This prevents watercraft users from launching in an infested waterbody and unintentionally transporting mussels or their larvae. Records will be kept of each inspection and will include the date, seal number, watercraft CF number, and trailer license plate number.   

Blue Oroville launch seals will only be applied if the watercraft passes inspection.

• Mussels cannot be present. 
• All water-containing areas of the watercraft and trailer must be 100 percent dry.

To avoid inspection failure: 

• Clean off aquatic plants, animal material, mud, dirt, and other debris from your watercraft, trailer, and equipment before arriving at the Inspection Station.  

• Drain the ballast, bilge, live-wells, and other water-containing areas of the vessel. 

• Dry water-containing areas of the watercraft, trailer, and equipment, including bilge, interior, hull, live well, and other areas where water could collect before arriving at the Inspection Station.

DWR has been coordinating with other lake managers to potentially develop a reciprocity program which would allow boat owners to use other lakes without the need for a reinspection.

DWR is working with Yuba Water Agency on their plan to adopt procedures at New Bullards Bar that mirror those of Oroville, in an effort to provide some consistency for recreators in the region. Yuba Water is still developing their plan with a goal of implementing it in June.

Golden mussels range from ¾ inches to 2 inches in size and have a light to dark yellowish-brown to brown-colored shell. When golden mussel populations are established, they are difficult to control since they can become very abundant and are easily spread to new waterbodies. Golden mussels can alter aquatic ecosystems by filter-feeding on planktonic algae and changing the habitat structure which can damage fisheries, impact water delivery systems by clogging small-diameter pipelines, screens, and filters, and impact recreation by fouling boat hulls and motors and clogging intakes and cooling lines. Mussel larvae, also referred to as veligers, are microscopic and free floating in infested waters and can be transported in a boat’s live well, ballast tank, or in the bilge if these areas are not completely drained. 

Additional details about golden mussels and an informational video are available on DWR’s website. 

Video Filming at Oroville Dam

On Tuesday, May 13, Oroville Dam and nearby recreation areas will look like the set of a popular police drama for an all-day video shoot featuring the Butte County Sheriff’s Office (BCSO). As part of a recruitment effort, BCSO will be filming scenes on Lake Oroville, along Oroville Dam Crest Road, and along the Brad Freeman Trail near the Diversion Pool. Public members should expect to see numerous emergency vehicles with flashing lights, a helicopter landing, and sheriff’s deputies in gear throughout the day.

To assist with video production, the parking area near Oroville Dam’s main spillway will be closed. In addition, Oroville Dam Crest Road will be intermittently closed for 15-minute intervals between 5 p.m. and 8 p.m. for a simulated pursuit scene. Vehicle and pedestrian traffic will be held by BCSO and California Highway Patrol staff during these periods.

Lake Oroville Nearing Capacity

With warming temperatures and ongoing mountain snowmelt in the Feather River watershed, Lake Oroville is nearing full capacity. DWR has decreased total releases from Lake Oroville to optimize storage for the benefit of water supply, recreation, and fish and wildlife enhancement.

As the lake nears full capacity, windy periods are likely to cause water to splash onto and over the crest of the emergency spillway. This will result in minor surface wetting of the downstream side of the emergency spillway crest and the very upper sections of the splash pad. Visitors to Oroville Dam may also notice minor amounts of water flowing from drains built into the emergency spillway. Both conditions are normal and expected given the emergency spillway design. The dam and emergency spillway continue to operate as intended.

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

• Current Oroville Reservoir Level: 895 feet elevation
• Current Storage: 98 percent of capacity
• Total Releases to the Feather River: 1,700 cubic feet per second

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 and mountain snow levels to optimize water storage while allowing for carryover storage into next year.

Feather Fiesta Days

For more than 70 years, Feather Fiesta Days has been Oroville’s premier hometown celebration. A large variety of community activities are scheduled this weekend through Sunday, May 11. Head downtown on Saturday for the Fiesta Street Fair, Gold Rush Car Show, Feather Fiesta Days Parade, craft fair at the Lott Home, and vendor and food booths.

Stop by DWR’s booth in downtown Oroville between 10 a.m. and 4 p.m. on Saturday. We’ll be sharing information about Lake Oroville recreation areas, and we’ll have fun, free activities for kids and families.

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

Road Closure for Tree Removal

DWR and its partners at the California Conservation Corps (CCC) and Butte County Sheriff’s Office are closing a portion of Canyon Drive for tree and vegetation removal. Canyon Drive will be closed between Oroville Dam Crest Road and Royal Oaks Drive (Upper Oroville Dam Overlook) Monday, May 12 through Thursday, May 15 between 7 a.m. and 4:30 p.m. DWR is performing fuel load reduction activities to minimize fire risk in areas surrounding Lake Oroville. Oroville Dam Crest Road will remain open to visitors during nearby tree removal work.

DWR’s Fuel Load Management Plan is dedicated to reducing wildfire risk, enhancing public safety, and improving forest health around Lake Oroville. During vegetation management activities some trails within the Lake Oroville State Recreation Area may be intermittently closed. Trail users should use caution in active work areas and follow all posted signage.

Current Lake Operations

Lake Oroville is at 895 feet elevation and storage is approximately 3.34 million acre-feet (MAF), which is 98 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 1,050 cfs being released from the Thermalito Afterbay River Outlet (Outlet) for a total Feather River release of 1,700 cfs downstream. 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 5/8/2025.