Roberta Delaney Gayle Hartmann v. Environmental Protection Agency

Residents of Maricopa and Pima counties, Arizona, petition this court to vacate as arbitrary and capricious the Environmental Protection Agency’s approvals of the counties’ Clean Air Act implementation plans. We have jurisdiction under 42 U.S.C. § 7607 (b)(1) (1982). We vacate the EPA’s approvals of the plans, and direct the EPA to take further action consistent with this opinion.

BACKGROUND

The Clean Air Act, as amended in 1970, mandated that states as expeditiously as practicable, but not later than December 31, 1975, reduce the levels of certain ambient pollutants to comply with the National Ambient Air Quality Standards set by the EPA. 42 U.S.C. § 7409 (a), (b) (1982). Preliminarily, each state had to develop a state implementation plan to achieve this goal. 42 U.S.C. § 7410 (a) (1982).

After many areas of the country failed to attain some or all of the national ambient air quality standards on time, Congress amended the Act in 1977, providing new deadlines for nonattainment areas. 42 U.S.C. §§ 7501-7508 (1982). The 1977 amendments required states to submit by January 1, 1979, for each of their nonat-tainment areas, a revised implementation plan that provided for…