Lake Oroville Update - July 26, 2024

Blue Green Algae Monitoring

Department of Water Resources (DWR) environmental scientists continue to monitor for blue-green algae and their toxins within the Oroville-Thermalito Complex. Monitoring occurs during the summer months with water samples taken at various locations regularly, which are sent to a lab for toxin analysis. There are currently no harmful algal bloom (HAB) advisories for Lake Oroville, the Thermalito Forebay, or the Thermalito Afterbay.

 

Blue-green algae (cyanobacteria) is 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. Algal blooms can make the water appear green, blue, or brown in color. Seeing colors, mats, foam, scum, or paint-like streaks in the water may indicate a bloom is present. Keep animals and children away from the water when a suspected bloom is present and report blooms immediately to the California Regional Water Quality Control Board.

 

If elevated levels of cyanobacteria toxins are found while testing, 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 HABs, or to report a HAB visit the Water Board’s website.

 

Oroville Dam Citizens Advisory Commission

The California Natural Resources Agency is hosting its 17th Oroville Dam Citizens Advisory Commission meeting on Friday, August 2 from 10 a.m. to noon. The virtual public meeting will include presentations and public comment. Presentations will include: an annual dam safety project update from the California Department of Water Resources; an overview of a recent independent assessment of the State Water Project Dam Safety Program; a briefing on the role of the state’s Division of Safety of Dams; and a report from the Sutter Butte Flood Control Agency on the process to update local inundation maps. The Citizens Advisory Commission is a forum for questions and feedback from the communities surrounding Oroville Dam. For more information about the meeting, please visit the Oroville Dam Citizens Advisory Commission website.

 

Nesting Grebes Receive Help From DWR

During the summer months, a unique bird makes its home in the waters around the Oroville-Thermalito Complex, with a little help from the Department of Water Resources (DWR). The Western and Clark’s grebes are aquatic birds with distinctive red eyes and pointed yellow beaks. During the summer, they arrive from the Pacific Ocean to nesting areas around the Thermalito Afterbay in Oroville. The grebes nest in shallow waters, attaching their floating nests to aquatic vegetation.

 

Unfortunately, fluctuations in water levels at reservoirs can either leave nests stranded, more susceptible to predators, or flooded. Every year since 2004, DWR has established a goal of keeping Thermalito Afterbay water levels within a targeted range until the end of the birds’ breeding and nesting season in September.

 

DWR biologists have observed active grebe nesting at the Thermalito Afterbay. Watercraft users are advised to remain alert for floating nests and to motor/paddle around them to leave nests undisturbed. DWR is conducting grebe surveys to estimate adult and young populations at the Afterbay through early October.

 

Oroville Recreation

Lake Oroville is one of the State Water Project’s premier recreational destinations and one of California’s best fishing spots. The lake provides both warm-water and cold-water fisheries and is a popular destination for bass tournaments.  The marinas at Bidwell Canyon and Lime Saddle are open daily and provide a variety of services including a convenience store, gas, boat rentals, and more. Below the Oroville Dam, the Thermalito Afterbay and the Feather River offer additional excellent fishing opportunities.

 

DWR, State Parks, and the California Department of Fish and Wildlife (CDFW) maintain over 92 miles of trails in the Oroville area. An interactive map of recreation facilities, including open trails and their permitted uses (hike, bike, horse, multi), is available on DWR’s Lake Oroville Recreation webpage. A paper trail map is available at various locations, including most entrance kiosks and the Lake Oroville Visitor Center.

 

Staffed by knowledgeable guides, the Lake Oroville Visitor Center features interpretive displays on Oroville Dam, area geology, wildlife and habitat, hydroelectric power, and cultural and historical artifacts. View videos in the theater about the construction of Oroville Dam, walk or hike along nearby trails, and visit the 47-foot-tall observation tower that provides unsurpassed panoramic views of surrounding areas. Free guided tours for school and community groups are available by reservation. Parking and admission to the Visitor Center are free.

 

Upstream migrating fish totals through the Feather River Fish Monitoring Station between January 1 and July 21 are:  

• Spring-run Chinook salmon (March 1 through June 30): 7,122
• Fall-run Chinook salmon (July 1 through present): 999
• Steelhead: 895

 

Current Lake Operations

Lake Oroville is at 861 feet elevation and storage is approximately 2.85 million acre-feet (MAF), which is 83 percent of its total capacity and 118 percent of the historical average. Updates to Lake Oroville’s storage capacity went into effect on July 1.

 

Feather River flows are at 1,500 cfs through the City of Oroville with 6,500 cfs being released from the Thermalito Afterbay River Outlet (Outlet) for a total Feather River release of 8,000 cfs downstream.  DWR continues to assess Feather River releases daily. 

 

Releases from Oroville Dam’s main spillway ceased earlier this summer, but water is still being released through the Hyatt Powerplant for power generation, water deliveries, and environmental requirements. When the main spillway is not in use, water may still be seen on the main spillway outlet as the seals on the eight radial gates are not designed to be watertight. The gate seals do not play a role in the structural integrity of the gates. Visitors to Oroville Dam may also notice minor amounts of water flowing from drains built into the emergency spillway. This is normal and expected given the emergency spillway design. The dam and emergency spillway continue to operate as intended.

 

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 7/25/2024.

 

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Know someone who would like to receive Community Updates? They can email their request to oroville@water.ca.gov.