## Facts

- West Virginia revised its Clean Water Act § 303 water-quality standards by adopting antidegradation implementation procedures and submitted them to the EPA for approval.
- EPA approved the state’s antidegradation policy and implementation procedures under 40 C.F.R. § 131.12.
- Environmental organizations and individual citizens sued the EPA under the APA, alleging the approval was arbitrary and capricious and inconsistent with federal antidegradation requirements; the parties filed cross-motions for summary judgment.
- West Virginia’s procedures classified waters into tiers, including Tier 1, Tier 2 (high-quality waters), and a Tier 2.5 category with additional criteria and protections.
- The procedures included categorical exclusions from antidegradation review for certain discharge categories (including some existing permitted discharges, publicly owned treatment works, and activities covered by general permits).
- The procedures adopted “de minimis” thresholds allowing up to a 10% reduction in assimilative capacity from an individual discharge and up to a 20% cumulative reduction from multiple discharges before triggering full Tier 2 review.
- EPA approved the designation of certain large rivers (including segments of the Kanawha and Monongahela Rivers) as Tier 1 waters rather than Tier 2, despite evidence that some segments exceeded minimum criteria.
- The procedures included numeric criteria and pollutant “trading” provisions for Tier 2.5 waters.

## Issues

1. Whether EPA acted arbitrarily and capriciously in approving West Virginia’s tier classifications, including treating certain high-quality river segments as Tier 1 rather than Tier 2.
2. Whether EPA could approve categorical exemptions from antidegradation review for certain discharge categories without site-specific analysis required by 40 C.F.R. § 131.12(a)(2).
3. Whether EPA reasonably approved the 10% individual de minimis threshold and the 20% cumulative de minimis threshold for assimilative-capacity reductions.
4. Whether EPA adequately justified approving Tier 2.5 numeric criteria and pollutant trading provisions as consistent with federal antidegradation requirements.

## Decision

- Plaintiffs’ motion for summary judgment was granted in substantial part; EPA’s and intervenors’ motions were denied to the extent inconsistent with the ruling.
- The court held EPA’s approval was arbitrary and capricious in multiple respects and did not ensure the minimum protections required by the federal antidegradation regulation.
- The court rejected EPA’s approval of treating certain high-quality river segments as Tier 1 based on an insufficient administrative rationale.
- The court rejected EPA’s approval of broad categorical exemptions that bypassed individualized antidegradation review for covered discharges and general-permit activities.
- The court upheld EPA’s approval of the 10% individual de minimis threshold as reasonably explained in the record.
- The court rejected EPA’s approval of the 20% cumulative de minimis threshold as unsupported by the record.
- The court found EPA had not adequately supported approval of Tier 2.5 numeric criteria and trading provisions.
- The court vacated EPA’s approval of West Virginia’s antidegradation implementation procedures and remanded to EPA for further proceedings consistent with the opinion.

## Legal Principles

- Under the APA, EPA action approving state water-quality standards and implementation procedures must be supported by reasoned decision-making and an administrative record that explains the agency’s choices.
- The federal antidegradation regulation, 40 C.F.R. § 131.12, requires protection of existing uses and imposes enhanced protections for high-quality waters, including a determination—made on a case-by-case basis—whether any lowering of water quality is necessary to accommodate important social or economic development.
- Antidegradation analysis is waterbody- and segment-specific; categorical tiering or categorical presumptions cannot substitute for the location-specific determinations required for high-quality waters.
- Categorical exclusions that remove entire discharge classes from antidegradation review are inconsistent with federal requirements unless EPA demonstrates, with support in the record, that the exclusions still maintain and protect high water quality.
- De minimis thresholds may be permissible only if EPA provides a rational, evidentiary basis; cumulative-impact thresholds require record support addressing aggregate degradation.
- Numeric criteria and trading regimes for protected waters must be justified with an explanation showing how the measures will maintain and protect water quality consistent with antidegradation requirements.

## Conclusion

The court vacated and remanded EPA’s approval of West Virginia’s antidegradation implementation procedures because EPA failed to provide an adequate, record-based justification for tier classifications, categorical exemptions, a 20% cumulative de minimis threshold, and Tier 2.5 criteria and trading provisions, while sustaining only the 10% individual de minimis standard as reasonably supported.


Ohio Valley Env’t Coal. v. Horinko, 279 F. Supp. 2d 732 (S.D.W. Va. 2003)