National Parks Conservation Ass'n v. United States Environmental Protection Agency

SHEPHERD, Circuit Judge.

Six environmental protection groups (the Environmental Groups) sued the EPA in an effort to impose emission-control technology on Northern States Power Company’s (NSP) Sherburne County power plant (Sherco). NSP moved to intervene. The district court denied NSP’s motion. We reverse the district court’s order and hold that NSP has standing to intervene and is entitled to intervene as of right.

I

The Clean Air Act (CAA) declared a national goal of remedying and preventing man-made visibility impairments in mandatory class I Federal areas. See 42 U.S.C. § 7491(a)(1). The EPA…