426 U.S. 128 (1976)
Cappaert v. United States is a landmark Supreme Court decision that clarified the interplay between federal reserved water rights and the protection of endangered species.
Does the United States have the right to reserve water from underground sources to preserve the habitat of the endangered Devil's Hole pupfish under the federal reserved water rights doctrine?
Under the federal reserved water rights doctrine, when the United States withdraws land from the public domain and reserves it for a federal purpose, it implicitly reserves sufficient water to fulfill the purpose of the reservation.
The Supreme Court unanimously held that the federal government has the right to reserve the necessary water for Devil's Hole to maintain water levels sufficient to protect the habitat of the endangered Devil's Hole pupfish.
Cappaert v. United States is significant as it reinforces federal reserved water rights, particularly as they pertain to the necessity of protecting endangered species and their habitats. This case highlights the precedence of federal environmental protection goals over private water use claims. It is a critical study for law students focusing on natural resources law, water rights, and the scope of federal powers in relation to environmental conservation.