Clark Canyon Dam is constructed at the head of the Beaverhead River. The zoned earthfill dam has a structural height of 147.5 feet, a crest length of 2,950 feet, and a volume of 1,970,000 cubic yards of material. The spillway consists of an approach channel, concrete inlet channel, ungated concrete crest, concrete chute, concrete stilling basin, and an outlet channel. The outlet works consists of an approach channel; concrete intake structure; concrete conduit; a gate chamber with high-pressure gates, two of which serve for emergency ahead of the regulating gates; concrete access shaft and shaft house; and a concrete stilling basin. The outlet channel is shared by the outlet works and spillway.