What are the facts?
International Paper Company operated a paper mill in Ticonderoga, New York, that discharged effluent into Lake Champlain pursuant to an NPDES permit administered by New York (under delegated federal authority). Vermont landowners, including plaintiff Ouellette, alleged that discharges from International Paper's New York point source polluted the Vermont side of Lake Champlain, causing noxious odors, slime, and other injuries to their riparian property. They filed a putative class action seeking damages and injunctive relief in a Vermont court, advancing claims under Vermont common law (including nuisance). International Paper argued that the Clean Water Act preempted the application of Vermont law to an out-of-state source and that any state-law claims must arise, if at all, under New York (the source state) law. The lower courts allowed the Vermont-law claims to proceed. On certiorari, the Supreme Court addressed the extent to which the CWA preempts state common-law claims in interstate water pollution cases.
What is the legal issue?
Does the Clean Water Act preempt a downstream (affected) state from applying its own common law (e.g., nuisance) to an out-of-state point source, or may plaintiffs pursue only the source state's law for interstate water pollution claims?
What rule applies?
The Clean Water Act's comprehensive permitting scheme preempts the application of an affected state's common law to an out-of-state point source. However, the Act does not preempt state common-law claims brought under the law of the source state. The Act's savings provisions preserve the source state's ability to impose and enforce more stringent requirements on its own dischargers, including through common-law remedies, but do not authorize extraterritorial application of another state's tort law that would conflict with or undermine the NPDES program.
What did the court hold?
The CWA preempts application of Vermont common law to International Paper's New York discharge. Plaintiffs may not proceed under Vermont law but may pursue claims under New York (the source state's) law. The judgment was reversed and remanded to allow plaintiffs to amend their complaint to assert source-state claims.
What is the reasoning?
1) Statutory structure and uniformity: The CWA establishes a nationally uniform permitting regime for point-source discharges through NPDES permits issued by EPA or authorized states. Allowing every affected state to impose its own tort law on out-of-state dischargers would subject permit holders to inconsistent, potentially conflicting obligations, eroding the uniformity and predictability the Act seeks to achieve. Both injunctive and damages remedies under affected-state law could functionally impose additional effluent limitations beyond the permit, thereby disrupting the federal-state permitting balance. 2) Savings clauses limited to source-state regulation: Section 510 (33 U.S.C. § 1370) preserves states' authority to adopt and enforce more stringent limitations than federal law, but it is best read to allow a state to regulate its own sources—not to export its law into other states. Likewise, the citizen-suit savings clause (33 U.S.C. § 1365(e)) does not broadly preserve all state-law claims that would conflict with the Act's permitting scheme. Reading the savings clauses to authorize affected-state law would permit precisely the extraterritorial regulation Congress sought to avoid. 3) Compatibility of source-state claims: By contrast, applying the source state's law is consistent with the CWA's cooperative federalism: the source state's stricter substantive standards—whether statutory or common-law—can be integrated into permitting decisions, with affected states afforded opportunities for notice and comment and with federal oversight. This approach avoids multiple, conflicting regulatory regimes while preserving state capacity to exceed federal baselines for their own dischargers. 4) Prior precedent: Building on City of Milwaukee v. Illinois (Milwaukee II), which held that the CWA displaces federal common law of interstate water pollution, the Court clarified that state common law still has a role—but limited by the Act's structure. Permitting affected-state claims would reintroduce the very fragmentation and conflict Milwaukee II and the CWA's framework sought to eliminate.
Why is this case significant?
Ouellette is the leading case on the CWA's preemptive effect over interstate state-law tort claims. It delineates a bright-line choice-of-law rule: only the source state's law may govern tort suits against out-of-state point sources. This preserves state common-law remedies without allowing downstream states to impose extraterritorial standards that would destabilize the NPDES program. For law students, the case is essential for understanding environmental federalism, the scope of statutory preemption, how savings clauses operate, and the strategic implications for forum selection and choice of law in pollution litigation.
Does Ouellette eliminate all state tort remedies for interstate water pollution?
No. Ouellette preserves state tort remedies, but limits them to the source state's law. Downstream plaintiffs may sue under the law of the state where the discharge originates. What is preempted is the application of the affected (downstream) state's law to an out-of-state source.
If a discharger has an NPDES permit, are state tort claims barred?
Not categorically. The permit shield protects a permittee from certain CWA enforcement actions, but does not automatically bar source-state tort claims. Under Ouellette and the CWA's savings clauses, the source state may impose and enforce more stringent obligations—including through common-law nuisance—on its own dischargers. However, remedies must be consistent with the Act's framework.
Which state's law applies to an interstate water pollution nuisance suit after Ouellette?
Only the law of the source state (where the point source is located). The affected state's law is preempted when applied extraterritorially to an out-of-state source. Plaintiffs must plead and prove claims under the source state's common law.
How does Ouellette relate to City of Milwaukee v. Illinois (Milwaukee II)?
Milwaukee II held that the CWA displaces federal common law of interstate water pollution. Ouellette complements that holding by clarifying that, while federal common law is displaced, state common law remains available—but only the source state's law may govern suits against out-of-state dischargers.
What tools do affected (downstream) states have if they cannot apply their own tort law?
Affected states can participate in the permitting process through notice, comment, and intergovernmental coordination; seek federal oversight; enforce their own water quality standards indirectly via EPA review; and encourage private plaintiffs to sue under the source state's law. They may also bring citizen suits under the CWA where authorized, but cannot use their own common law to regulate out-of-state sources.