Dedicated on August 24, 1975, The Libby Dam impounds the Kootenai River about 17 miles upstream from the town of Libby, Montana. Libby Dam is over 420 feet high and over 3,000 feet long. Lake Koocanusa is the name of the 90 miles reservoir upriver from the dam. Over 40 miles of Lake Koocanusa are in British Columbia, Canada. The Libby Dam is the fourth dam constructed under the Columbia River Treaty. Libby Dam holds back 5,800,000 acre feet of water.
The dam is operated by the United States Army Corps of Engineers. The Libby dam is designed with a withdrawal system that allows water to pass from different levels of Lake Koocanusa. This allows the Libby Dam operators to moderate water temperatures and oxygen levels downstream.