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Libby Dam


Libby Dam
Completed: 1973
Operator: USACoE
Type: Dam and storage, reservior


The Libby Dam in the State of Montana was built in 1972 by the US Army Corps of Engineers to control the flood waters of the Kootenay River and provide hydroelectricity to the Bonneville Power Administration (BPA) in the United States for its customers in western part of the country from California to Washington to Montana. Construction of the dam began in 1966 and at the peak of construction employed over 2000 people. Construction of the powerhouse began in May of 1972 and continued through 1985 with the completion of Unit #5. The dam is 128 m (422 ft) tall and 931 m (3055 ft) long has five Francis-type turbines, each with a capacity of 120 megawatts (120 million watts). At peak times, the dam can generate 600 megawatts. The money earned from electricity sales goes to the United States Treasury and will repay the cost of building and operating Libby Dam.

The building of the Libby Dam created the reservoir known as Koocanusa (named for KOOtenay, CANada and USA) that extends northward 145 km (90 mi) - 77km (48 mi) on the southern side of the International border and another 68 km (42 mi) on the northern portion.

In Montana, prior to the flooding, the town of Rexford was moved to higher ground, where a new school, water system, sewage system, fire station, post office and road were built. The State Highway 37 was also relocated to higher ground on the east side of the reservoir. A forest development road was established along the west side of the reservoir. Koocanusa Bridge, Montana's longest, 743 m (2,437 ft), and highest, 82 m (270 ft), bridge, was built to provide additional access across the north end of the reservoir. Relocating the Great Northern Railroad line was one of the most complex of all the projects. Relocation cost more than $100.6 million dollars, nearly 30 percent of the total dam construction budget - and included a seven-mile railroad tunnel through Elk Mountain.

Lake Koocanusa holds 13 percent of the total water stored in the Columbia River system, The value of this water is multiplied because it will be used to produce power sixteen times before it reaches the Pacific Ocean.

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Libby Dam
Libby Dam

Aerial view Libby dam, upstream view. Image courtesy U.S. Army Corps of Engineers
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