Devil Canyon Authorization Act - States that, in order to provide essential power and a backbone transmission grid for south-central and interior Alaska, and to develop and utilize available renewable energy resources to assist in meeting long-range national objectives for conservation of petroleum and natural gas supplies, and for other purposes, the Secretary of the Army, acting through the Chief of Engineers, is authorized to construct and the Secretary of the Interior is authorized to operate and maintain the Devil Canyon and Denali units of the Upper Susitna River Basin project, Alaska. Provides that electric power and energy generated at the Upper Susitna River Basin project, except that portion required for project operation, shall be disposed of by the Secretary of the Interior in such a manner as to encourage the most widespread use thereof at the lowest possible rates to consumers consistent with sound business principles. Directs the Secretary of the Army to proceed with preparation of project designs and an environmental impact statement in accordance with the National Environmental Policy Act, and directs the Secretary of the Interior to proceed with a determination of necessary and feasible electric power transmission facilities and power marketing studies. Authorizes appropriations of $1,000,000 for the purpose of conducting these studies.