Texas v. New Mexico: End to a 13-Year Rio Grande Water Battle

The U.S. Supreme Court recently closed the book on one of the most consequential interstate water disputes in recent memory. On May 26, 2026, the Court entered a final consent decree in Texas v. New Mexico and Colorado (No. 141, Orig. (2026)), ending litigation that began when Texas sued New Mexico in 2013, alleging that groundwater pumping below Elephant Butte Reservoir was depriving Texas of its share under the 1938 Rio Grande Compact.

The road to resolution was not smooth. In June 2024, the Court took the rare step of rejecting an earlier settlement the three states had negotiated. In a narrow 5-4 decision authored by Justice Ketanji Brown Jackson, the Court held that the states could not enter a consent decree disposing of the federal government’s Compact claims without the United States’ consent, recognizing the federal government's “unique” interests in the Rio Grande Project and its treaty obligations to Mexico. The parties were sent back to the negotiating table.

This time, the federal government was on board. Under the approved settlement, New Mexico must reduce annual groundwater depletions by 18,200 acre-feet within ten years, retire certain irrigated farmland, and operate under a new, enforceable water-accounting framework governing deliveries to Texas.

As significant as this decision is for the Rio Grande, the implications extend well beyond the Rio Grande. The 2024 ruling confirmed an expanded federal role in administering interstate compacts, signaling to water practitioners nationwide that the United States may now claim a seat at the table in compact enforcement, even where it is not a signatory. Stated differently, the federal government’s claims by inter-state decree, even where the states are unanimous and a special master approves, must be considered from day one. The Rio Grande parties succeeded by (1) leaving the economically-negotiated accounting deal intact, and (2) building a parallel set of agreements that let the U.S. resolve and voluntarily dismiss its own claims while affirmatively protecting Reclamation’s project operations and the Mexico Treaty deliveries.