VIRGINIA ELECTRIC AND POWER COMPANY, Appalachian Power Company, Baltimore Gas and Electric Company, Carolina Power & Light Company, Duke Power Company, Monongahela Power Company, Potomac Edison Company, Potomac Electric Power Company, South Carolina Electric & Gas Company, West Penn Power Company, Indiana & Michigan Electric Company, Kentucky Power Company, Ohio Power Company, Boston Edison Company, Cincinnati Gas & Electric Company, Cleveland Electric Illuminating Company, Columbus & Southern Ohio Electric Company, Commonwealth Edison Company, Consolidated Edison Company of New York, Inc., the Dayton Power and Light Company, the Detroit Edison Company, Florida Power & Light Company, Houston Lighting & Power Company, Illinois Power Company, Long Island Lighting Company, Arkansas-Missouri Power Company, Arkansas Power & Light Company, Mississippi Power & Light Company, Louisiana Power & Light Company, New Orleans Public Service, Inc., Middle South Utilities, Inc., Montaup Electric Company, National Rural Electric Cooperative Association, New England Power Company, New York State Electric & Gas Corporation, Niagara Mohawk Power Corporation, Holyoke Water Power Company, the Connecticut Light and Power Company, the Hartford Electric Light Company, Western Massachusetts Electric Company, Ohio Edison Company, Ohio Valley Electric Corporation, Pacific Gas and Electric Company, Pennsylvania Power & Light Company, Philadelphia Electric Company, Public Service Company of New Hampshire, Public Service Electric & Gas Company, San Diego Gas & Electric Company, Southern California Edison Company, Alabama Power Company, Georgia Power Company, Gulf Power Company, Mississippi Power Company, Tampa Electric Company, Dallas Power & Light Company, Texas Electric Service Company, Texas Power & Light Company, the Toledo Edison Company, Union Electric Company, Wisconsin Electric Power Company, Appellants,
Jersey Central Power & Light Company, Metropolitan Edison Company and Pennsylvania Electric Company, Intervening Plaintiffs,
v.
Douglas M. COSTLE, as Administrator, Environmental Protection Agency, and the United States Environmental Protection Agency, Appellees.