Tellico Dam and the snail darter (1978)
The Supreme Court halted the nearly finished Tellico Dam on the Little Tennessee River in 1978, ruling it would wipe out the only habitat of the snail darter, a tiny fish listed under the Endangered Species Act. The project was roughly 90% complete and had cost over $100 million.
Congress exempted the dam from the Endangered Species Act in 1979 through an appropriations rider. It was completed and flooded the river.
The case established that species protection can stop major federal projects, and that Congress can override those protections.
It shows both halves of this story: courts blocking projects over wildlife concerns, and Congress retaining the power to override, as with the appropriations review now facing the SpaceX exchange.
