History
The powerplant originally served hatchery loads and station service requirements for Trinity and Judge Francis Carr Powerplants. Administration of the contract was transferred to Western in 1977 and the interconnection contract with Pacific Gas and Electric was canceled in 1989. A new interconnection contract was signed in 1990.
The Shasta and Trinity River Division of the Central Valley Project was authorized by Public Law 386, 84th Congress, 1st Session, approved August 12, 1955.
The Central Valley Project, one of the Nation`s major water conservation developments, extends from the Cascade Range on the north to the semiarid but fertile plains along the Kern River on the south. Initial features of the project were built primarily to protect the Central Valley from crippling water shortages and menacing floods. New project units were built to provide water and power to match the continued growth of the State.
Although developed primarily for irrigation, this multiple-purpose project also provides flood control, improves Sacramento River navigation, supplies domestic and industrial water, generates electric power, conserves fish and wildlife, creates opportunities for recreation, and enhances water quality.
The Trinity River Division consists of Trinity Dam and Clair Engle Lake, Trinity Powerplant, Lewiston Dam and Lake, Lewiston Powerplant, Clear Creek Tunnel, Judge Francis Carr Powerhouse, Whiskeytown Dam and Lake, Spring Creek Tunnel and Powerplant, Spring Creek Debris Dam and Reservoir, and related pumping and distribution facilities. These facilities were built and are operated by the Bureau of Reclamation.
Funds for construction of the initial features of the Central Valley Project were provided by the Emergency Relief Appropriation Act of 1935 (49 Stat. 115). The Secretary of the Interior authorized the project and the President approved it on December 2, 1935.
Plan
Lewiston Powerplant is operated in conjunction with the spillway gates to maintain the minimum flow in the Trinity River downstream of the dam. The turbine is normally set at maximum output with the spillway gates adjusted to regulate river flow. It provides power to the adjacent fish hatchery. Lewiston Dam is a zoned earthfill structure 91 feet high and 25 feet wide at the crest. The crest is 754 feet long. Transmission lines were constructed and operated by the Bureau of Reclamation until October 1, 1977, when they were transferred to the Western Area Power Administration, Department of Energy. The powerplant originally served hatchery loads and station service requirements for Trinity and Judge Francis Carr Powerplants. Administration of the contract was transferred to Western in 1977 and the interconnection contract with Pacific Gas and Electric was canceled in 1989. A new interconnection contract was signed in 1990. Lewiston maintains and regulates river releases. Energy in excess of hatchery loads is sold to Pacific Gas and Electric at 15 mills per kilowatt-hour. The turbine capacity is exceeded by the Trinity River minimum flow. There are options to increase the capacity at Lewiston that are not economical at the current price of power. Western Electricity Coordinating Council, California-So. Nevada Power Area Western Area Power Administration, Sierra Nevada Region Conventional Above Ground 350 kW 350 kW 1964 3,335,000 kWh 2007 Francis 43 years 60 ft