Kootenai River

River in British Columbia, Canada and the US states of Montana and Idaho; length 721 km/448 mi. Following a tortuous course that runs south and then turns sharply west and northwest, it eventually joins the Columbia River 32 km/20 mi southwest of Nelson, British Columbia.

The Kootenai River rises in the southeast of British Columbia, flows through Kootenay National Park and south into northwestern Montana, northwest of the town of Eureka. Flowing through Lake Koocanusa, the waters of the river are impounded by the Libby Dam. The river turns west and runs past Libby before continuing northwest into Idaho. Cutting northwest across the northern tip of the state, it re-enters British Columbia at the southern end of Lake Kootenay. It then flows out of the western arm of the lake past Nelson and enters the Columbia River.