Alabama Power Company v. Douglas M. Costle, as Administrator, Environmental Protection Agency, Sierra Club, Intervenors.

This case concerns the validity of final regulations 1 promulgated by the Environmental Protection Agency (EPA) on June 19,1978 embracing the prevention of significant deterioration of air quality in the nation’s “clean air areas.” 2 These “PSD” regulations interpreted and began the implementation of various provisions of the Clean Air Act Amendments of 1977. 3 Pertinent provisions are gathered in title I, part C of the Clean Air Act as amended (hereafter sometimes referred to as the “PSD part” or the “PSD provisions”).

Before us are consolidated petitions for review filed in this court, as…