## Facts

- A consortium of suburban Chicago municipalities selected an abandoned 533-acre sand-and-gravel pit in Illinois for a landfill.
- After mining ended, excavation trenches became permanent and seasonal ponds used by migratory birds.
- The landfill plan would have filled some ponds, so the consortium asked the U.S. Army Corps of Engineers whether a Clean Water Act (CWA) § 404 permit was required.
- The CWA authorizes § 404 permits for discharges of dredged or fill material into “navigable waters,” defined as “waters of the United States.”
- Corps regulations treated certain intrastate waters as “waters of the United States” if their use, degradation, or destruction could affect interstate or foreign commerce.
- The Corps relied on its 1986 “Migratory Bird Rule,” asserting jurisdiction over intrastate waters that provide habitat for migratory birds crossing state lines.
- The Corps asserted jurisdiction over the ponds under the Migratory Bird Rule and denied the requested § 404 permit.

## Issues

1. Whether the CWA’s reference to “navigable waters,” as implemented by Corps regulations and the Migratory Bird Rule, authorizes § 404 jurisdiction over isolated, intrastate, non-navigable ponds used by migratory birds.
2. If the statute authorizes such jurisdiction, whether that interpretation is a permissible exercise of Congress’s Commerce Clause power.

## Decision

- The Supreme Court reversed the Seventh Circuit.
- The Court held that applying 33 C.F.R. § 328.3(a)(3) to the site through the Migratory Bird Rule exceeded the authority granted under CWA § 404(a).
- The Court concluded that § 404(a) does not extend to isolated, intrastate ponds that are not adjacent to navigable waters when the only asserted basis for federal jurisdiction is migratory bird habitat.
- The Court resolved the case on statutory grounds and did not reach the Commerce Clause question.
- Distinguishing prior precedent upholding regulation of wetlands adjacent to navigable waters, the Court declined to extend jurisdiction to non-adjacent, isolated waters.
- The Court applied a clear-statement approach, reasoning that major alterations to the federal-state balance in land and water use require unmistakably clear congressional authorization, which was absent here.

## Legal Principles

- “Navigable waters” in the CWA retains limiting force; an interpretation that effectively reads “navigable” out of the statute is disfavored.
- CWA § 404 jurisdiction recognized for wetlands adjacent to navigable waters does not, without more, extend to isolated, intrastate, non-adjacent waters.
- Agency interpretations that would expand federal authority into traditional state domains require a clear statutory statement from Congress.
- When an agency’s construction would raise serious constitutional questions (including Commerce Clause concerns), courts may prefer a narrower reading that avoids those questions.

## Conclusion

The Court held that the Corps lacked statutory authority under CWA § 404(a) to regulate isolated, intrastate ponds based solely on migratory bird use, invalidating the Migratory Bird Rule as applied and limiting federal jurisdiction over non-adjacent waters absent clear congressional authorization.


Solid Waste Agency of N. Cook Cnty. v. U.S. Army Corps of Eng'rs, 531 U.S. 159 (2001)