Koocanusa

Koocanusa is a large artificial reservoir on the Kootenai River that straddles the United States–Canada border. It was created by Libby Dam in Montana and extends north into southeastern British Columbia. The name Koocanusa is a blend of Kootenai, Canada, and United States. The reservoir is roughly 90 miles (145 kilometers) long, making it one of the long artificial reservoirs in the region. The American portion lies in western Montana, while the Canadian portion lies in British Columbia.

The reservoir serves several purposes. It provides hydroelectric power generation at Libby Dam, helps with flood control downstream, and aids in managing river flows across the border. The project is operated by the U.S. Army Corps of Engineers as part of the Libby Dam system, with cross-border considerations for water releases and ecosystem management.

Recreation and ecology are important aspects of Koocanusa. The reservoir supports fisheries for species such as rainbow trout and kokanee salmon, among others, and is a popular site for boating, camping, and fishing. Water levels and temperatures are influenced by seasonal operations, drought conditions, and dam management, which can affect habitats and fish populations. Cross-border cooperation between U.S. and Canadian authorities is typically involved in stewardship of the reservoir and its regional environment.