Clean Water Action Council of Northeastern Wisconsin, Inc. v. United States Environmental Protection Agency

EASTERBROOK, Circuit Judge.

The Clean Air Act, 42 U.S.C. §§ 7401-7671q, invites each state to craft a plan (a “state implementation plan”) to control the levels of certain air pollutants. Most state plans include “Prevention of Significant Deterioration” (PSD) programs. These programs are designed to prevent backsliding in “attainment areas” (regions that meet or exceed the Act’s air quality standards), while still allowing some new sources of pollution. A PSD program prevents designated sources from propelling the region’s aggregate emissions over specified limits. The Act establishes these…