## Facts

- The Tennessee Valley Authority (TVA), a federal agency, was constructing the Tellico Dam on the Little Tennessee River; by the mid-1970s the project was substantially complete and had received over $100 million in federal funding.
- Congress enacted the Endangered Species Act of 1973 (ESA) to conserve endangered species and the ecosystems on which they depend.
- In 1975, the Secretary of the Interior listed the snail darter, a small fish, as an endangered species and designated the portion of the Little Tennessee River to be inundated by the dam’s reservoir as the species’ critical habitat.
- Under ESA §7, the Secretary issued a regulation requiring federal agencies to ensure their actions do not destroy or modify critical habitat.
- Citizens and environmental plaintiffs sued under the ESA’s citizen-suit provision to enjoin completion and operation of the dam, alleging impoundment would destroy critical habitat and jeopardize the snail darter’s continued existence.
- The district court found impoundment would probably jeopardize the snail darter but denied injunctive relief, relying on equitable considerations and Congress’s continued appropriations for the project.
- The Sixth Circuit reversed and ordered a permanent injunction unless Congress expressly exempted the project or changed the ESA.

## Issues

1. Whether ESA §7 requires a federal agency to halt or modify a nearly completed federal project when continued operation would jeopardize an endangered species or destroy its critical habitat.
2. Whether Congress’s continued appropriations for the Tellico Dam after the ESA’s enactment and the snail darter’s listing impliedly repealed or modified ESA §7 as applied to the project.

## Decision

- The Supreme Court affirmed the Sixth Circuit, holding that ESA §7 imposes a mandatory duty on federal agencies to ensure their actions do not jeopardize endangered species or destroy or modify critical habitat.
- The Court held the statute applies to ongoing and nearly completed projects; it is not limited to projects begun after the ESA’s enactment.
- The Court rejected equitable balancing that would allow a court to deny an injunction based on sunk costs or project completion status when §7 is violated.
- The Court held continued appropriations did not create an implied exemption from ESA §7; implied repeals require a clear and manifest congressional intent, which was absent.
- The Court upheld a permanent injunction against completion and operation of the Tellico Dam absent an explicit congressional exemption.

## Legal Principles

- ESA §7’s “shall” language creates a substantive, mandatory constraint on federal agency action: agencies must avoid actions that jeopardize listed species or destroy or modify designated critical habitat.
- When Congress issues clear statutory commands, courts may not substitute equitable balancing to dilute or avoid the statute’s requirements.
- The ESA applies to federal actions regardless of a project’s stage of completion unless Congress provides an express statutory exemption.
- Repeal or modification of substantive law by appropriations measures is disfavored; implied repeal requires clear and manifest evidence of congressional intent, and funding alone is insufficient.

## Conclusion

The Court held that ESA §7 required stopping a nearly completed federal dam project that would eradicate critical habitat for an endangered species, and that continued congressional funding did not impliedly exempt the project from the statute’s mandatory protections.


Tennessee Valley Authority v. Hill, 437 U.S. 153 (1978)