The Elk River is a 220-kilometre (140 mi) long river, in the southeastern Kootenay district of the Canadian province of British Columbia. Its drainage basin is 4,450 square kilometres (1,720 sq mi) in area. Its mean discharge is approximately 60 cubic metres per second (2,100 cu ft/s), with a maximum recorded discharge of 818 cubic metres per second (28,900 cu ft/s). It is a tributary of the Kootenay River, and falls within the basin of the Columbia River.

Lake Koocanusa is a reservoir in British Columbia (Canada) and Montana formed by the damming of the Kootenai River by the Libby Dam in 1972. The Dam was formally dedicated by President Gerald Ford on August 24, 1975.