Whatshan Dam was built by the B.C. Power Commission and completed in 1952. It is a concrete hydroelectric dam on the Whatshan River in the Canadian province of British Columbia. The previous powerhouse was flooded by the construction of the Keenleyside Dam, the replacement 54MW powerhouse completed in 1972 is at the end of a 3.4 kilometre long tunnel and is located on the western side of Lower Arrow Lake in the Monashee Mountains.