## Facts

- Pinto Creek in Arizona was listed as impaired for dissolved copper and classified as a water-quality-limited water under Clean Water Act (CWA) § 303(d).
- EPA developed a total maximum daily load (TMDL) for copper for the relevant segment of Pinto Creek and allocated the allowable copper load among existing sources.
- Carlota Copper Company proposed a new open-pit copper mine and sought an NPDES permit to discharge mine-related pollutants, including copper, to Pinto Creek and nearby waters.
- EPA issued the permit, concluding that Carlota’s additional copper loading could be offset by reductions from remediation at an existing source (the old Gibson Mine), resulting in a net watershed reduction.
- Environmental organizations challenged the permit through EPA’s Environmental Appeals Board, which denied review, and then petitioned for judicial review in the Ninth Circuit.

## Issues

1. Whether EPA may issue an NPDES permit to a new discharger into a water body already violating water quality standards when the receiving segment’s TMDL leaves no remaining wasteload allocation for the new discharge.
2. Whether EPA’s reliance on offsets from reductions at other sources satisfies 40 C.F.R. § 122.4(i)’s prohibition on permitting new dischargers whose discharges will “cause or contribute” to violations of water quality standards.

## Decision

- The court granted the petition for review.
- The court vacated the NPDES permit and remanded to EPA.
- The court held that EPA unlawfully issued the permit because Carlota’s discharge would add copper to an already-impaired receiving segment that had no remaining wasteload allocation under the applicable TMDL.
- The court rejected EPA’s offset rationale as inconsistent with the permit- and receiving-segment-specific limits imposed by 40 C.F.R. § 122.4(i) and the TMDL framework.

## Legal Principles

- Under 40 C.F.R. § 122.4(i), EPA may not issue an NPDES permit to a new source or new discharger if its discharge will cause or contribute to the violation of water quality standards in impaired waters unless the relevant TMDL provides sufficient remaining wasteload allocation for that discharge.
- TMDL wasteload allocations for point sources must be implemented through permits in a manner that ensures compliance with water quality standards under CWA § 301(b)(1)(C).
- A net watershed improvement theory does not satisfy § 122.4(i) when the specific receiving segment remains impaired and the proposed new discharge would increase pollutant loading in that segment beyond what the TMDL allows.
- Agency interpretations that conflict with the clear text and structure of the governing regulation are not entitled to deference.

## Conclusion

The Ninth Circuit set aside EPA’s permit for a new copper mine discharge into an already copper-impaired creek because the receiving segment’s TMDL left no remaining wasteload allocation, and offsets from other sources could not cure the regulatory bar on new dischargers that would cause or contribute to ongoing water quality violations.


Friends of Pinto Creek v. U.S. Environmental Prot. Agency, 504 F.3d 1007 (9th Cir. 2007)