Texas v. New Mexico and Colorado

This original jurisdiction case involves the 1938 Rio Grande Compact between Texas, New Mexico, and Colorado. Texas sued New Mexico, alleging that excessive groundwater pumping by farmers south of Elephant Butte Reservoir was depleting surface water legally apportioned to Texas. The United States intervened to protect its treaty obligations and federal reclamation project operations. On June 21, 2024, the U.S. Supreme Court ruled 5-4, rejecting a proposed consent decree between Texas and New Mexico because it was opposed by the federal government. The majority, led by Justice Kavanaugh, held that a state cannot settle a water compact dispute without the consent of the United States when federal interests are at stake, remanding the case for further litigation.

The U.S. Supreme Court ruled 5-4 in favor of the United States, determining that the proposed consent decree could not be approved over federal objections. The case was remanded for further proceedings under the original case file.

The central dispute focused on whether New Mexico's groundwater use violated the Rio Grande Compact by reducing deliveries to Texas, and whether the federal government had the authority to veto a settlement agreement between the states.

The ruling significantly reinforces federal supremacy in interstate water compacts, potentially complicating future settlement negotiations in the arid American West. It affirmed that the Justice Department holds broad authority to block state-led water agreements involving shared river basins if it perceives a threat to federal projects or treaty obligations.