## Facts

- Landowners in Oklahoma’s Potato Hills alleged that oil and gas operations at numerous sites caused stormwater, wetlands, and point-source-discharge violations under the Clean Water Act (CWA).
- Plaintiffs filed an initial 2004 CWA citizen suit after sending notice letters; the district court dismissed without prejudice for insufficient notice, describing the notices as overly broad and nonspecific.
- The EPA investigated the complained-of sites, brought a federal CWA enforcement action against two GHK-related entities, and entered a court-enforced consent decree.
- The consent decree addressed stormwater and point-source discharges and included wetlands findings and mitigation requirements at certain sites; the targeted entities could ensure compliance across GHK sites.
- Plaintiffs then sent a second round of notice letters and filed a new citizen suit against the GHK defendants and additional defendants (Wynn–Crosby Energy, KCS Resources, and El Dorado Dozers).
- The district court dismissed: (1) claims against GHK defendants as barred by EPA “diligent prosecution,” and (2) claims against the non-GHK defendants for legally insufficient notice, treated as a jurisdictional defect.

## Issues

1. Whether EPA’s federal enforcement action and consent decree constituted “diligent prosecution” barring a CWA citizen suit against the GHK defendants under 33 U.S.C. § 1365(b)(1)(B).
2. Whether plaintiffs’ second notice letters satisfied 33 U.S.C. § 1365(b)(1)(A) and 40 C.F.R. § 135.3 as to Wynn–Crosby, KCS Resources, and El Dorado Dozers.

## Decision

- The Tenth Circuit affirmed dismissal of the action in full.
- EPA’s enforcement action and consent decree qualified as “diligent prosecution,” precluding the citizen suit against the GHK defendants.
- Plaintiffs’ second notice letters remained insufficiently specific as to the non-GHK defendants, depriving the district court of subject-matter jurisdiction over those claims.

## Legal Principles

- A CWA citizen suit is barred if EPA has commenced and is diligently prosecuting an action in federal court “to require compliance” with the Act. 33 U.S.C. § 1365(b)(1)(B).
- The diligence inquiry focuses on whether the government action is capable of requiring compliance and is brought in good faith; it is not defeated merely because the agency did not pursue every alleged violation or the remedy sought by citizens.
- Courts generally defer to EPA’s enforcement judgments regarding scope, targets, and remedies when EPA is actively enforcing the CWA through a court action and consent decree.
- CWA citizen-suit plaintiffs must provide 60 days’ pre-suit notice to alleged violators, EPA, and the state. 33 U.S.C. § 1365(b)(1)(A).
- Notice must include, to the extent known, the specific standard/limitation/order allegedly violated, the violative activity, responsible persons, and the location and dates of violations. 40 C.F.R. § 135.3.
- Generalized, “shotgun” notices that broadly cite the CWA or describe violations in vague terms do not satisfy the notice requirement.
- Failure to comply with the CWA notice requirement is a jurisdictional defect requiring dismissal.

## Conclusion

The Tenth Circuit held that EPA’s court-enforced consent decree constituted diligent prosecution barring overlapping Clean Water Act citizen claims against the GHK defendants, and it separately held that plaintiffs’ nonspecific pre-suit notices failed to confer jurisdiction over claims against the remaining defendants.


Karr v. Hefner, 475 F.3d 1192 (10th Cir. 2007)