## Facts

- The Environmental Protection Agency (EPA), acting under the Clean Water Act (CWA), promulgated effluent limitation guidelines for the non‑ferrous metals manufacturing industry to control discharges of toxic metals into navigable waters.
- EPA conducted a multi-year rulemaking that involved data collection, technical studies, and review of public comments before issuing final limits based on “best available technology economically achievable” (BAT).
- EPA selected “lime, settle, and filtration” as the model wastewater treatment technology for controlling combined metals and relied on a cross-industry dataset called the Combined Metals Data Base (CMDB) to derive numeric limitations.
- EPA applied the resulting limitations broadly across segments of the non‑ferrous metals industry, including primary base metals plants that did not necessarily use the model process.
- Industry petitioners challenged the rule, asserting the CMDB was unrepresentative of primary metals operations, sampling was insufficient for reliable long-term limits, and the limits were technologically and economically unachievable.
- Petitioners also contested EPA’s use of supplemental sulfide precipitation for certain pollutants and argued EPA failed to provide adequate notice of key data and statistical methods during notice-and-comment.
- EPA responded that treatability depended largely on solubility characteristics, that established statistical methods could reasonably project long-term performance from available samples, and that it considered but was not required to adopt industry-submitted data.

## Issues

1. Whether EPA’s effluent limitations, derived from the CMDB and the model technology (with possible supplemental sulfide precipitation), were reasonable, achievable, and supported by the administrative record under CWA/APA review standards.
2. Whether EPA acted unlawfully or arbitrarily by declining to adopt industry-submitted data in favor of the CMDB and EPA’s statistical analyses.
3. Whether EPA provided sufficient notice and a meaningful opportunity to comment on the data, methodologies, and technological assumptions underlying the final rule.

## Decision

- The Fourth Circuit denied the petitions for review and upheld EPA’s effluent limitation guidelines.
- The court held EPA’s technical judgments and data choices were supported by the record and fell within a permissible range of reasoned decision-making under deferential review.
- The court concluded EPA was required to consider industry submissions but was not required to accept them or base the rule on industry-preferred datasets.
- The court rejected challenges to EPA’s sampling and statistical methods, accepting EPA’s approach to accounting for variability and projecting long-term performance.
- The court held the rulemaking satisfied notice-and-comment requirements because regulated entities received a meaningful opportunity to participate.
- While the court noted isolated weaknesses in EPA’s explanations for particular data characterizations, it found no basis to invalidate the rule given the record as a whole.

## Legal Principles

- Under the CWA and the APA, courts defer to EPA’s reasonable scientific and technical judgments and will not substitute judicial views for agency expertise absent arbitrariness, caprice, or legal error.
- EPA must consider data and comments submitted by regulated parties, but it is not obligated to accept those submissions or adopt regulated parties’ preferred assumptions, models, or datasets.
- EPA may rely on representative and cross-industry data, including model-technology performance data, and may use statistical methods to translate limited sampling into enforceable effluent limits, if the record rationally supports comparability and methodology.
- Notice-and-comment is satisfied when the agency discloses the core basis of the proposal and affords a meaningful opportunity to comment; the agency need not disclose every internal calculation or methodological detail so long as participation is fair and informed.

## Conclusion

The Fourth Circuit sustained EPA’s non‑ferrous metals effluent limits, holding that EPA reasonably relied on a model technology and cross-industry data, permissibly declined to adopt industry-preferred data, and provided adequate notice-and-comment under the CWA and the APA.


Kennecott v. EPA, 780 F.2d 445 (4th Cir. 1985)