## Facts

- The Clean Air Act (CAA) requires EPA to set ozone National Ambient Air Quality Standards and assigns states primary responsibility to meet them through EPA-approved state implementation plans (SIPs).
- Under the 1990 CAA Amendments, ozone nonattainment areas are classified (marginal to extreme), with fixed attainment deadlines and mandatory planning and control obligations by classification.
- EPA designated the Washington, D.C. Metropolitan Area (District of Columbia and nearby Maryland and Virginia counties) as a “serious” ozone nonattainment area in 1991.
- Serious areas were required to attain the one-hour ozone standard by November 15, 1999.
- The District of Columbia, Maryland, and Virginia submitted revised SIPs that did not provide for attainment by the 1999 deadline and instead sought an attainment date of November 15, 2005.
- EPA approved the revised SIPs and the later attainment date, reasoning that the Washington Area was a downwind receptor affected by transported ozone and precursors from upwind areas.
- Sierra Club petitioned for review, arguing EPA lacked authority to approve SIP revisions that effectively extended the statutory deadline and to approve SIPs that omitted required elements for a serious area.

## Issues

1. Whether EPA may approve SIP revisions that effectively extend a serious nonattainment area’s statutory attainment deadline based on ozone transport without using the CAA’s reclassification mechanism.
2. Whether EPA may approve serious-area SIPs that do not include reasonably available control measures (RACM), required annual rates of progress, and contingency measures.
3. Whether EPA’s approval was arbitrary and capricious under the Administrative Procedure Act.

## Decision

- The court granted Sierra Club’s petition for review.
- The court held EPA exceeded its statutory authority by approving SIP revisions that effectively extended the attainment deadline beyond the date fixed by the CAA without following the statute’s reclassification scheme.
- The court held EPA’s approval was arbitrary and capricious in approving SIPs that failed to satisfy mandatory serious-area requirements, including RACM, rates of progress, and contingency measures.
- The matter was remanded to EPA for further proceedings consistent with the court’s decision.

## Legal Principles

- CAA ozone attainment deadlines tied to nonattainment classifications are fixed by statute; EPA may not extend them through SIP approval absent explicit statutory authorization.
- When an area fails to attain by its deadline, the CAA prescribes reclassification consequences; EPA cannot accomplish a de facto reclassification by approving a later attainment date while avoiding associated statutory obligations.
- Transport-related provisions addressing interstate pollution do not displace the CAA’s classification-and-deadline structure or excuse compliance with mandatory SIP elements for the area’s classification.
- EPA action approving SIPs must be consistent with statutory requirements and supported by reasoned decisionmaking; approval that departs from the statutory scheme or excuses mandatory elements is arbitrary and capricious.

## Conclusion

The D.C. Circuit rejected EPA’s attempt to extend a serious-area ozone attainment deadline through SIP approval based on downwind transport and held that EPA also unlawfully approved SIPs lacking required measures and demonstrations, remanding for further agency action consistent with the CAA.


Sierra Club v. EPA, 294 F.3d 155 (D.C. Cir. 2002)