## Facts

- An environmental organization alleged that stormwater runoff from Oregon logging roads carried sediment into rivers and streams through ditches, culverts, and similar conveyances.
- The organization filed a Clean Water Act (CWA) citizen suit against Oregon forestry officials and timber companies, claiming unpermitted discharges of a pollutant from “point sources” in violation of the NPDES permitting program.
- The defendants relied on EPA regulations, including the Silvicultural Rule and the Industrial Stormwater Rule, arguing that ordinary logging-road runoff was not subject to NPDES permitting.
- The district court dismissed the suit, concluding the challenged discharges did not require NPDES permits.
- The Ninth Circuit reversed, holding the conveyances were point sources and the runoff required permits.
- While Supreme Court review was pending, EPA amended its stormwater regulations to clarify that the logging-road stormwater permitting requirement applied only to certain listed silvicultural facilities (e.g., rock crushing, gravel washing, log sorting, log storage), not ordinary logging roads.

## Issues

1. Whether 33 U.S.C. § 1369(b) bars a CWA citizen suit against alleged violators when the suit depends on contesting the meaning or effect of an EPA regulation.
2. Whether EPA’s intervening regulatory amendment mooted the case.
3. Whether, under the pre-amendment regulatory scheme, channeled stormwater runoff from logging roads was a discharge “associated with industrial activity” requiring an NPDES permit.

## Decision

- The Court held that § 1369(b) did not bar the citizen suit because it was an enforcement action against alleged violators under § 1365, not a direct challenge to EPA action.
- The Court held the case was not moot because past discharges could still support civil penalties even if future discharges would not require permits under the amended rule.
- On the merits, the Court reversed the Ninth Circuit, holding that the discharges at issue did not require NPDES permits under EPA’s reasonable interpretation of the pre-amendment Industrial Stormwater Rule.
- The Court deferred to EPA’s interpretation of its own regulation (Auer/Seminole Rock deference), finding no indication the interpretation was a post hoc litigation position or a break from prior practice.
- Chief Justice Roberts (joined by Justice Alito) concurred, accepting deference here while raising concerns about the doctrine’s breadth.
- Justice Scalia concurred in part and dissented in part, agreeing on jurisdiction and mootness but rejecting deference and concluding permits were required.

## Legal Principles

- CWA § 1369(b)’s channeling of certain EPA-action challenges to courts of appeals does not, by itself, preclude a § 1365 citizen suit seeking to enforce existing statutory or regulatory obligations against regulated parties.
- A regulatory amendment does not necessarily moot an enforcement case when liability or penalties for past conduct remain possible.
- Under Auer/Seminole Rock, a court generally defers to an agency’s reasonable interpretation of its own ambiguous regulation, including when the agency’s view is presented during litigation, absent indications of unfair surprise or an invented post hoc rationale.
- EPA reasonably construed “stormwater discharges associated with industrial activity” to exclude stormwater from ordinary logging roads because the conveyances were tied to timber harvesting in forests rather than to manufacturing, processing, or raw-material storage areas at an industrial plant.

## Conclusion

The Court allowed the citizen suit to proceed procedurally and found the dispute still live despite EPA’s later rule change, but it ultimately held—deferring to EPA’s interpretation of its stormwater regulations—that most channeled stormwater runoff from logging roads was not “associated with industrial activity” and therefore did not require NPDES permits under the pre-amendment rules.


Decker v. Nw. Env’t Def. Ctr., 568 U.S. 597 (2013)