Lake Oroville Update - October 17, 2025

North Fork Algal Bloom Cleared

An algal bloom in the upper reaches of Lake Oroville in the North Fork arm between Stony Creek and the train tunnel below French Creek has cleared after several weeks. Water testing did not detect toxins.

What are signs of algal blooms?

• Small blue-green, green, white, or brown particles in the water
• Streaks in the water that look like spilled paint
• Mats, scum, or foam at the surface or along the shoreline
• Can have an odor described as gasoline, septic, or fishy

Blue-green algae (cyanobacteria) are a natural component of ecosystems. Under certain conditions, including warmer temperatures and increased nutrient loads, algae can grow rapidly causing "blooms." Algal blooms sometimes produce toxins that can be harmful to people and animals.

Department of Water Resources (DWR) environmental scientists routinely monitor for blue-green algae and their toxins within the Oroville-Thermalito Complex. Monitoring occurs during the summer with water samples taken at various locations regularly, which are sent to a lab for toxin analysis. If testing reveals elevated levels of cyanobacteria toxins, DWR staff will work with California's Regional Water Quality Control Board and recreation area managers to notify the public and post advisory signs at affected waterbodies. To learn more about harmful algal blooms (HAB), or to report a HAB visit the Water Board's website.

Oroville Dam Citizens Advisory Commission

The California Natural Resources Agency is hosting its 21st Oroville Dam Citizens Advisory Commission (OCAC) meeting on Friday, Oct. 24 from 10 a.m. to noon. The public meeting will be held in-person in Oroville at the Southside Oroville Community Center (2959 Lower Wyandotte Rd., Multipurpose Room). The agenda includes presentations and an opportunity for public comment. Presentations will include annual Oroville facility updates on the budget, prioritization of future dam safety projects, and the status of current dam safety projects and related studies. There will also be brief updates on the US Army Corps of Engineers' Water Control Manual Update process and the Commission's 2023-2025 Legislative Report.

The Citizens Advisory Commission is a forum for questions and feedback from communities surrounding Oroville Dam. For more information, please visit the Oroville Dam Citizens Advisory Commission website.

Loafer Creek Fuel Reduction Activities

As part of ongoing fuel reduction work within the Lake Oroville State Recreation Area (LOSRA), DWR is coordinating with the Butte County Sheriff's Office (BCSO), the California Conservation Corps (CCC), and CAL FIRE to remove hazardous fuels in the Loafer Creek area. Crews are continuing to prepare areas along State Route 162 and near the Loafer Creek campgrounds and boat launch. Prescribed burning is tentatively scheduled Oct. 21-22 depending on weather conditions and CAL FIRE crew availability.

In addition, a CAL FIRE grant-funded project supported by DWR, the Department of Parks and Recreation (State Parks), the Butte County Fire Safe Council (BCFSC), and the Mooretown Rancheria of Maidu Indians continued fuel reduction work this week in the Loafer Creek area near State Route 162. Approximately 140 acres will be treated by hand crews and heavy equipment over the next several months.

During vegetation management activities some trails within the Loafer Creek area may be intermittently closed. Trail users should use caution in active work areas and follow all posted signage. Oroville-area residents should expect to see smoke from prescribed fires in the coming weeks.

DWR appreciates the public's cooperation and understanding as it works to reduce wildfire risk, increase public safety, and support long-term land management goals. Vegetation management remains a top priority for DWR and its partners.

Upcoming Road Closures for Guardrail Work

DWR is continuing work on a $1.9 million paving and sealing project to rehabilitate several locations owned and maintained by the department that are heavily used by maintenance staff and members of the public. Project work is expected to continue through November 2025. Vintage Paving Company, Inc. of Winters, Calif. is the contractor for the project.

Upcoming construction work will require closures to the following public areas and roads:

• Aug. 18 - Oct. 31: Afterbay Dam Crest Road/Brad Freeman Trail south of State Route 162 to the East Hamilton Road Trail Access
• Oct. 27 - Oct. 29: Canyon Drive from the intersection of Oroville Dam Blvd. E./Royal Oaks Drive heading north to the dam and upper overlook will be closed to vehicles daily from 6:30 a.m. to 6:30 p.m.
• Oct. 30 - Oct. 31: Oroville Dam Boulevard East between Oro Powerhouse Road and the intersection at Canyon Drive/Royal Oaks Drive will be closed to vehicles daily from 6:30 a.m. to 6:30 p.m.

Additional locations for future paving and sealing work include:

• Thermalito Diversion Dam Powerplant

• Oroville Field Division Operations and Maintenance Center at Glen Drive

DWR will provide more details about scheduled work and potential public access impacts in future newsletters. Work schedules are subject to change based on weather and the availability of equipment and materials.

Golden Mussel Inspection Program

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

Watercraft Inspection Location/Decontamination Services

North Thermalito Forebay at Garden Drive and HWY 70 in Oroville

Hours of operation: Daily from 8:30 a.m. to 5:30 p.m.

Starting Nov. 3: Daily from 8:30 a.m. to 4:30 p.m.

Sealed Vessel Launching

Lake Oroville

Ramp hours: Daily from 7:30 a.m. to 6:30 p.m.

• Spillway

Ramp hours: Monday-Thursday 7:30 a.m. to 6:30 p.m.; Friday-Sunday 7:30 a.m. to 8 p.m.

• Bidwell Canyon

Ramp hours: Monday-Thursday 5 a.m. to 6:30 p.m.; Friday-Sunday 5 a.m. to 8 p.m.

• Lime Saddle

Ramp hours: Daily from 5 a.m. to 6:30 p.m.

• Loafer Creek/Loafer Point

Thermalito Afterbay

Ramp hours: Daily from 1.5 hours before sunrise to 1 hour after sunset

• Monument Hill

Thermalito Forebay

Ramp Hours: Daily from 8 a.m. to sunset

• North Forebay (Non-motorized vessels only)

Feather River Fish Monitoring Station

Between Jan. 30 and April 20, high flows in the Feather River required the temporary removal of fish monitoring equipment resulting in lower spring-run estimates. Upstream migrating fish totals through the Feather River Fish Monitoring Station between Jan. 1 and Oct. 11, 2025 are:

• Spring-run Chinook salmon (April 16 through June 30): 17,713
• Fall-run Chinook salmon (July 1 through present): 15,301
• Steelhead: 673
• To see previous year data, visit CalFish.org.

Current Lake Operations

Lake Oroville is at 780 feet elevation and storage is approximately 1.89 million acre-feet (MAF), which is 55 percent of its total capacity and 102 percent of the historical average.

Feather River flows are at 650 cubic feet per second (cfs) through the City of Oroville with 1,800 cfs being released from the Thermalito Afterbay River Outlet (Outlet) for a total Feather River release of 2,450 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 10/16/2025.