Castlegar is a community in the West Kootenay region of British Columbia, Canada. In the Selkirk Mountains, at the confluence of the Kootenay …Castlegar is a community in the West Kootenay region of British Columbia, Canada. In the Selkirk Mountains, at the confluence of the Kootenay and Columbia Rivers, it is a regional trade and transportation centre, with a local economy based on forestry, mining and tourism.