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.

The Kootenay River or Kootenai River is a major river of the Northwest Plateau in southeastern British Columbia, Canada, and northern Montana and Idaho in the United States. It is one of the uppermost major tributaries of the Columbia River, the largest North American river that empties into the Pacific Ocean. The Kootenay River runs 781 kilometres (485 mi) from its headwaters in the Kootenay Ranges of the Canadian Rockies, flowing from British Columbia's East Kootenay region into northwestern Montana, then west into the northernmost Idaho Panhandle and returning to British Columbia in the West Kootenay region, where it joins the Columbia at Castlegar.