## Facts

- The Clean Air Act regional haze program requires states to submit implementation plans containing measures to make “reasonable progress” toward natural visibility conditions in designated Class I areas.
- EPA’s Regional Haze Rule generally requires certain older, large stationary sources to install Best Available Retrofit Technology (BART), but permits states to use an alternative program if it yields “greater reasonable progress” than BART (“better-than-BART”).
- In 2012, EPA revised the regional haze regulations and determined that compliance with the Cross-State Air Pollution Rule (CSAPR) could qualify as a better-than-BART alternative for certain states and pollutants.
- EPA partially disapproved multiple state plans that had relied on the Clean Air Interstate Rule (CAIR), CSAPR’s predecessor, and issued federal implementation plans (FIPs) to apply until states submitted approvable replacements incorporating CSAPR.
- Conservation organizations challenged EPA’s conclusion and analytical method for treating CSAPR as better-than-BART.
- State and industry petitioners, including Utility Air Regulatory Group, challenged EPA’s disapproval of CAIR-based state plans and the issuance of FIPs.
- The consolidated petitions were reviewed under the Administrative Procedure Act’s arbitrary-and-capricious standard, with substantial deference to EPA’s technical judgments.

## Issues

1. Whether EPA reasonably concluded that CSAPR compliance may serve as a lawful better-than-BART alternative for regional haze purposes in covered states.
2. Whether EPA’s method for comparing emissions reductions and visibility benefits under CSAPR versus BART was lawful and adequately explained.
3. Whether EPA lawfully disapproved state plans premised on CAIR and promulgated FIPs after CAIR had been held unlawful and CSAPR issued.
4. Whether EPA’s visibility modeling choices and “reasonable progress” determinations were arbitrary or inadequately explained.

## Decision

- The court largely denied the petitions for review and upheld EPA’s 2012 regional haze rule.
- The court sustained EPA’s determination that CSAPR could qualify as better-than-BART in covered states and upheld EPA’s comparative approach.
- The court upheld EPA’s disapproval of CAIR-based state plans and EPA’s issuance of FIPs pending new, approvable state submissions.
- The court remanded limited aspects for further agency consideration or explanation without disturbing the central CSAPR/better-than-BART and CAIR-disapproval determinations.

## Legal Principles

- Under the APA, an EPA rule is upheld if it is reasonable, explained, and not arbitrary or capricious; courts are especially deferential to EPA’s scientific and technical judgments.
- The regional haze provisions permit alternatives to source-specific BART where EPA reasonably finds the alternative achieves greater reasonable progress; the statute does not require a single comparison methodology.
- EPA may treat an applicable multi-state control program as the relevant baseline in assessing whether it provides better-than-BART results, so long as EPA reasonably explains its assumptions and modeling choices.
- EPA may disapprove state implementation plans that rely on an unlawful or superseded regulatory program and may impose federal implementation plans as an interim measure until states submit approvable plans.

## Conclusion

The D.C. Circuit largely upheld EPA’s regional haze rulemaking, concluding that EPA reasonably treated CSAPR as a better-than-BART alternative and properly rejected continued reliance on CAIR in state plans, while remanding only limited matters for additional explanation or proceedings.


Utility Air Regulatory Group v. EPA, 885 F.3d 714 (D.C. Cir. 2018)