Chilko Lake is a 180 km² lake in west-central British Columbia, at the head of the Chilko River on the Chilcotin Plateau. The lake is about 65 km long, with a southwest arm 10 km long. It is one of the largest lakes by volume in the province because of its great depth, and the largest above 1,000 m in elevation. It and Harrison Lake are the largest lakes in the southern Coast Mountains.