Pyramid Lake Paiute Tribe of Indians v. United States Department of the Navy

The Department of the Navy (Navy) (defendant) operated the Fallon Naval Air Station (Fallon Station) in Nevada. To mitigate risks and dangers caused by desert conditions in the area, such as poor visibility as a result of dust storms, the Navy surrounded the runways at Fallon Station with buffer zones containing irrigated vegetation. Water used to irrigate the vegetation was diverted from the Truckee River, and then it flowed into the Lahontan Reservoir. Drainage from the Truckee River was diverted into the Lahontan Reservoir and reduced the size of the nearby Pyramid Lake. Pyramid Lake was located on the Pyramid Lake Indian Reservation. Before water was diverted for the Navy’s irrigation project, the Truckee River flowed into Pyramid Lake. The Truckee River maintained Pyramid Lake’s level and provided river spawning flows for cui-ui, a species of fish. The cui-ui’s exclusive habitat was Pyramid Lake and was designated as an endangered species under the Endangered Species Act (ESA). The reduced flows of the Truckee River into Pyramid Lake led to a precarious condition for the cui-ui. The Pyramid Lake Paiute Tribe of Indians (the Tribe) alleged that the irrigation project’s diversion of the water seriously threatened the continued viability of the cui-ui. The Tribe argued that the ESA requires an agency to adopt an alternative to a challenged action if it would be equally as effective at serving the government’s interest and would enhance conservation more than the challenged action. The Tribe proposed an alternative to the Navy’s irrigation project that would use less water but still further the Navy’s interest in safety to the same degree. The Navy refused to accept the proposal because it would have an insignificant effect on the availability of water in the Truckee River for the preservation of the cui-ui. The Tribe argued that the Navy’s refusal to accept the proposal violated the ESA. The district court found that the conservation measures proposed by the Tribe would be insignificant and thus the Navy was not required under the ESA to adopt the proposed alternative.