Nat’l Parks Conservation Ass’n v. EPA

Under the Clean Air Act, when the Environmental Protection Agency implements regulations regarding regional haze at a plant where the best available retrofit technology is already in place, the Environmental Protection Agency does not need to provide a detailed explanation for the regulation.

The National Parks Conservation Association (“NPCA”) and PPL Montana, LLC (“PPL Montana”), the partial owner of several hydroelectric power plants, petitioned for review of the Environmental Protection Agency’s (“EPA”) regional haze regulations. Regional haze, as defined by the Clean Air Act, is a “visibility impairment caused by geographically dispersed sources emitting fine particles and their precursors into the air.” The parties’ petitions were consolidated by the Ninth Circuit. NPCA and PPL Montana’s primary concern was that the EPA’s regulations prescribing emission limits at certain power plants lacked sufficient explanation. PPL Montana operates two plants affected by the regulations, Colstrip and Corette. Concerning Colstrip, the panel held that the EPA’s regulations were arbitrary and capricious. On the other hand, the panel held that the EPA was permitted to skip the remaining analysis and explanation regarding the Corette plant because it already had the “best available retrofit technology” in place. The panel further held that the EPA properly set emissions limits for Corette. Petitions for review GRANTED in Part and DENIED in Part; VACATED and REMANDED.