|Location||Lincoln County, Montana|
|Opening date||1975 (August 24)|
Corps of Engineers
|Dam and spillways|
|Type of dam||Concrete gravity|
|Height||422 ft (129 m)|
|Length||3,055 ft (931 m)|
|Spillway capacity||160,000 cu ft/s (4,500 m3/s)|
|Total capacity||6,027,000 acre⋅ft (7.434 km3)|
|Catchment area||8,985 sq mi (23,270 km2)|
|Surface area||46,700 acres (18,900 ha)|
|Installed capacity||600 MW|
|Annual generation||1,574.4 GWh|
Libby Dam is a concrete gravity dam in the northwestern United States, on the Kootenai River in northwestern Montana. Dedicated on August 24, 1975, it is west of the continental divide, seventeen miles (27 km) upstream from the town of Libby.
At 422 feet (129 m) in height and a length of 3,055 feet (931 m), Libby Dam created Lake Koocanusa, a reservoir which extends ninety miles (140 km) upriver with a maximum depth of about 370 feet (110 m). Forty-two miles (68 km) of it are in Canada in southeastern British Columbia.
Lake Koocanusa was named for the treaty that was developed between the Kootenai Indians, the Canadian government, and the U.S. government to build the dam and form the reservoir. It was the fourth dam constructed under the Columbia River Treaty. The Kootenai River is the third largest tributary to the Columbia River, contributing almost twenty percent of the total water in the lower Columbia. Libby Dam holds back an average of 5,800,000 acre feet (7.2 km3) of water.
In order to make way for the dam, the town of Rexford was relocated and a new Flathead Railroad Tunnel was dug. Construction began in 1966, and the reservoir was available for filling in mid-1973.
The dam is operated by the U.S. Army Corps of Engineers and at full capacity, it can pass over 160,000 cubic feet per second (4,500 m3/s) of water. The dam is designed with a selective withdrawal system that allows water passage from various levels of Lake Koocanusa, which allows the operators to moderate water temperatures downstream. The river continues northwest into Idaho, past Bonners Ferry, to Kootenay Lake in Canada and joins the Columbia River.
Libby Dam's powerhouse contains five turbines and is capable of generating 600 megawatts. The electricity is managed by the Bonneville Power Administration and services eight states: Montana, Idaho, Washington, Wyoming, California, Utah, Oregon, and Nevada. The money earned from electricity sales goes to the United States Treasury to repay the cost of building and operating Libby Dam.
President Gerald Ford was among the five thousand in attendance at the opening in 1975, along with Senator Mike Mansfield, the majority leader, and Governor Thomas Judge. At his first official event after a two-week vacation in Vail, Colorado, Ford "threw the switch" with Donald Macdonald, Canadian minister of energy.
- "Ford heads to Libby (Montana)". Lewiston Morning Tribune. (Idaho). Associated Press. August 24, 1975. p. 2A.
- Swigard, Kent (August 25, 1975). "Ford switches on Libby Dam". Spokesman-Review. (Spokane, Washington). p. 1.
- Floyd, Doug (August 25, 1975). "Dam gets Ford's praise, but it's not energy key". Spokane Daily Chronicle. (Washington). p. 1.
- Frohnen, Richard (June 20, 1965). "Libby Dam planner on job". Spokesman-Review. (Spokane, Washington). p. 15.
- "Libby Dam Virtual Tour". US Army Corps of Engineers. Archived from the original on 19 July 2009. Retrieved 14 March 2011. CS1 maint: discouraged parameter (link)