History

Agricultural activity in the Boise and Payette Valleys started in the early 1880`s when settlers began filing on desert lands under private irrigation enterprises. By 1900, about 148,000 acres had been placed under irrigation. It quickly became evident that storage and distribution systems were needed for a dependable water source to serve the lands at high elevations. In response to petitions by local irrigators, the Boise Project was initiated by the Reclamation Service shortly after the passage of the first Reclamation Act of 1902.

Project Authorization

Construction of the original Boise Project was authorized on March 27, 1905. The Secretary of the Interior authorized Anderson Ranch Dam and Reservoir on August 12, 1940, under the Reclamation Project Act of 1939 (53 Stat. 1187).

Plan

Anderson Ranch Dam and Powerplant is a multiple-purpose structure that provides benefits in irrigation, power, and flood and silt control. The plant supplies power to irrigation loads in the Boise, Owyhee, and Minidoka Projects as part of Reclamation`s Southern Idaho Power System. Surplus power is delivered to the BPA for marketing and distribution to regional industries and municipalities.

Located in a remote area, the powerplant has been remotely operated from the Black Canyon control center since 1984. The dam is 456 feet high (the world`s highest earthfill dam at the time of its completion in 1950), and has a total storage capacity of 474,900 acre-feet (active capacity 413,100). The powerplant originally had a rated capacity of 27,000 kilowatts with two units installed. In 1981, both generators were rewound and modernized to an increased capacity of 20,000 kilowatts each for a total of 40,000 kilowatts.

Project Purpose

The Boise Project furnishes irrigation water to about 225,000 acres of project lands and 165,000 acres under special and Warren Act contracts. The irrigable lands are in southwestern Idaho and eastern Oregon.

The Arrowrock Division consists of 164,680 irrigable acres, with supplemental water to an additional 111,115 acres. Water for the division is stored in Anderson Ranch Reservoir on the South Fork of the Boise River; Arrowrock Reservoir on the Boise River; and in Lake Lowell, an offstream lake in a large depression. Anderson Ranch Dam, the uppermost storage facility on the Boise system, is located 42 miles upstream from Arrowrock Dam.

Present Activities

The original power transformers and cables were replaced in Jan-Feb 2001. Station Service air compressors were replaced in 2002. The switchyard oil circuit breakers were replaced in Sept-Oct 2002, completing the modernization of the power plant switchyard. The power plant crane was modernized in April 2001, the fire suppression system replaced in 2004 and Life Safety Code Phase I improvements completed in 2000 and 2003. Generator excitation equipment and electrical transducers were replaced in 2007 .

Future Planned Activities

Investigation is underway to determine a schedule for overhaul or replacement of the original turbines.

Special Issues

The upper Boise River system is a renowned game trout fishery and has been proposed as critical habitat for bull trout, a threatened species under the Endangered Species Act.

General