lake oroville

Constructed at the foot of the Sierra Nevada Mountains in Northern California, the Oroville Facilities are located on the Feather River in Butte County and are also known as FERC Project No. 2100 or P-2100.

The principal features of P-2100 include Oroville Dam and Reservoir as well as Edward Hyatt Powerplant, Thermalito Facilities, Feather River Fish Hatchery, and associated recreational, fish and wildlife preservation and enhancement facilities. The hydroelectric facilities of P-2100 have a combined license capacity of approximately 762 megawatts which produce an average of 2.2 billion kilowatt-hours of electricity each year.


Picture of Oroville Dam and Lake
Oroville Dam and Lake
Picture of Oroville Facilities
Oroville Facilities

On February 11, 1957 the Department of Water Resources (DWR) was issued a 50-year license to construct and operate the Oroville Facilities (P-2100) in Butte County, California. The original license expired on January 31, 2007. During relicensing, a diverse group of agencies and stakeholders scoped issues, designed a $27 million suite of studies, reviewed reports, proposed measures, and discussed potential solutions for project impacts. Using relevant information from this effort, DWR filed an Application for New License with supporting environmental documentation on January 26, 2005. On March 26, 2006, DWR and an overwhelming majority of stakeholders successfully concluded negotiations and signed a Settlement Agreement that has been estimated to provide approximately $1 billion in environmental, recreational, cultural, and other benefits over a proposed 50-year new license term.

The Settlement Agreement was submitted as DWR's preferred alternative and became the focus of FERC's ongoing National Environmental Policy Act (NEPA) analysis. DWR, as lead agency under California Environmental Quality Act (CEQA), followed with an Environmental Impact Report (EIR) with the Settlement Agreement as the preferred project. A summary of key activities and documents from relicensing are presented below.

Key Activities:
The following additional actions have taken place since filing of the application for relicensing of the Oroville Facilities:

Related Documents:


Oroville Dam is the tallest earth-fill dam, at 770-feet, in the United States and forms Oroville Lake with a capacity of 3.5 million acre-feet (California's second largest reservoir). The facilities generate 762 megawatts (MW) of hydropower and provide storage to deliver water to areas of need. The spillway, located on the right abutment of the dam, has two separate elements: a controlled gated outlet and an emergency uncontrolled spillway designed to convey excess water over the spillway weir and down the undeveloped canyon slope to the river.

Lake Oroville is home to a wide variety of fish, and is regularly stocked by the California Department of Fish and Game. The lake's record-setting fishery provides anglers with a variety of catches such as crappie, catfish, rainbow and German brown trout, bluegill, and green sunfish. Noted for its bass (spotted, large-mouth and small-mouth, etc.) fishing, Lake Oroville is a popular spot for bass tournaments.
Edward Hyatt Powerplant has six generators (three for reversible pumpback operation), and a capacity of approximately 645 MW. In the bedrock beneath Oroville Dam, a cavern -large enough to hold almost two football fields- was blasted out to house Edward Hyatt Powerplant.
Thermalito Diversion Dam forms the Diversion Pool, 13,328 acre-feet gross capacity, on the Feather River immediately downstream from the tailrace of Edward Hyatt Powerplant. Constructed between 1963 and 1968, the Diversion Dam and Pool are located about 4.5 miles downstream from Oroville Dam. The dam has three purposes to: (1) divert water into the two-mile long Thermalito Power Canal, which transports water to the Ronald B. Robie Thermalito Powerplant for power generation; (2) create a tailwater pool (called the Diversion Pool) for the Hyatt Pumping-Generating Plant; and (3) provide headwater for the Thermalito Diversion Dam Powerplant.
Thermalito Diversion Dam Powerplant is located at Thermalito Diversion Dam below the left abutment of the dam. It was constructed between 1985 and 1987 and generates electricity from water released to the Feather River to maintain fish habitat between the Diversion Dam and Thermalito Afterbay river outlet. The plant facilities consist of intake headworks, inlet pipes, a single penstock, an underground powerhouse with one turbine unit, a tailrace channel and outlet works. The powerhouse measures approximately 53 feet long, 50 feet wide and 42 feet high.
Thermalito Power Canal hydraulically links the Diversion Pool to the Thermalito Forebay and conveys water in either direction between the two facilities. The headwork structure for the Thermalito Power Canal is located on the right abutment of the Thermalito Diversion Dam. The canal, 10,000 feet long, is designed to convey maximum generating and pumping flows of 16,900 cfs and 9,000 cfs, respectively. The canal is concrete-lined with a bottom width of 48 feet and 1.5 to 1 side slopes. Construction on the canal began in 1965 and was completed in 1967.
Thermalito Forebay, constructed between 1965 and 1968, is an offstream reservoir about four miles west of the city of Oroville. Thermalito Forebay is contained by Thermalito Forebay Dam on the south and east and by Campbell Hills on the north and west. It has a gross capacity of 11,768 acre-feet, and is formed by water releases from Lake Oroville and diverted by the Diversion Dam through Thermalito Power Canal. The forebay conveys generating and pumping flows between Thermalito Power Canal and Ronald B. Robie Thermalito Powerplant, provides regulatory storage and surge damping for the Hyatt-Thermalito power complex, and serves as a recreational site.
Ronald B. Robie Thermalito Powerplant is a principal feature of the Oroville-Thermalito pumped storage power complex. The facility is operated in tandem with Hyatt Powerplant and Thermalito Diversion Dam Powerplant to produce power. Water released for power in excess of local and downstream requirements is conserved by pumpback operation during off-peak hours through both powerplants into Lake Oroville to be subsequently released for power generation during periods of peak power demand. Construction on the plant began in 1964 and was completed in 1969, with operations starting in 1968.
Thermalito Afterbay has a gross storage capacity of 57,041 acre-feet. The afterbay provides storage for the water required by the pumpback operation to Lake Oroville, helps regulate the power system, produces controlled flow in the Feather River downstream from the Oroville-Thermalito facilities, and provides recreation. Water may be pumped back into Lake Oroville through Ronald B. Robie Thermalito and Edward Hyatt Powerplants; released to the Feather River Channel; or diverted directly to the Sutter Butte Canal, Western Lateral, and Richvale and Western Canal. Thermalito Afterbay Dam has the longest crest in the State Water Project system at 42,000 feet long. The facility was constructed from 1965 to 1968.
Thermalito Afterbay Outlet is situated in the southeast corner of the Afterbay, at a location convenient for discharge to the Feather River downstream of the Thermalito Diversion Dam. Water released from the outlet provides for downstream project use, stream flow maintenance, and water-right commitments.
The Feather River Fish Barrier Dam is downstream of the Thermalito Diversion Dam and immediately upstream of the Feather River Fish Hatchery. The flow over the dam maintains fish habitat in the low-flow channel of the Feather River between the Fish Barrier Dam and the Thermalito Afterbay Outlet. The dam diverts migrating salmon and steelhead into a fish ladder that leads to the hatchery. The fish ladder consists of a series of "steps" and pools with the maximum drop between pools of one foot.
The Feather River Fish Hatchery is one of California's largest hatcheries for salmon and steelhead. The hatchery is operated by the California Department of Fish and Game and funded by DWR.