Hells Canyon Dam is a concrete gravity dam on the Snake River (river mile 247) in Hells Canyon on the Idaho-Oregon border. The dam impounds the Snake River in Hells Canyon Reservoir; its spillway elevation is 512 m (1,680 ft) above sea level.
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It is the third and final hydroelectric dam of the Hells Canyon Project, which includes Brownlee Dam (1959) and Oxbow Dam (1961), all built and operated by Idaho Power Company. The Hells Canyon Complex on the Snake River is the largest privately owned hydroelectric power complex in the nation, according to the US Energy Information Administration. The contractor for the Hells Canyon Dam was Morrison-Knudsen.