Dedicated on August 24, 1975, Libby Dam spans the Kootenai River 17 miles (27 km) upstream from the town of Libby, Montana. Libby Dam is 422 feet tall and 3,055 feet long. The reservoir behind the dam is Lake Koocanusa; it extends 90 miles upriver from the dam and has a maximum depth of about 370 feet. Forty-two miles of Lake Koocanusa are in British Columbia, Canada. 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 is the fourth dam constructed under the Columbia River Treaty. The Kootenai River is the third largest tributary to the Columbia River contributing almost 20% of the total water in the lower Columbia. Libby Dam holds back an average of 5,800,000 acre feet of water.
The Company employed 60% Indian Band members for the construction of the dam who contributed immeasurably to the success of the project.