- The U.S. Supreme Court approved a major Rio Grande settlement on May 26, 2026.
- The agreement is designed to reduce groundwater pumping in southern New Mexico.
- New Mexico must retire groundwater rights tied to thousands of irrigated acres.
- The settlement ends more than a decade of litigation between Texas, New Mexico, and Colorado.
Thursday, May 28, 2026 — The U.S. Supreme Court has officially approved a historic settlement designed to reduce groundwater pumping along the Rio Grande and settle a long-running legal fight between Texas, New Mexico, and Colorado over one of the West’s most stressed rivers.
In a brief order issued May 26, 2026
, the Court entered the proposed final decree in the case Texas v. New Mexico, et al., formally approving the settlement package that had been negotiated by the states and federal government. The Court also discharged Special Master D. Brooks Smith, who had overseen years of negotiations and litigation.
The case began in 2013 when Texas accused New Mexico of allowing excessive groundwater pumping below Elephant Butte Reservoir, arguing that the pumping reduced flows reaching Texas under the Rio Grande Compact. The compact, signed in 1938, governs how water from the Rio Grande is divided among Colorado, New Mexico, and Texas.
At the heart of the dispute was the growing connection between groundwater pumping and river flows. The settlement agreement explains that the Rincon and Mesilla aquifers in southern New Mexico are “hydrologically connected” to the Rio Grande, meaning groundwater pumping can reduce surface water flows in the river itself.
The settlement package requires New Mexico to reduce groundwater-related depletions in the Lower Rio Grande by 18,200 acre-feet per year within ten years. Half of that reduction must occur within the first five years.
To meet those goals, New Mexico will permanently retire certain groundwater rights tied to irrigated farmland and other uses. The agreement lays out formulas for calculating those reductions. For example, each acre of groundwater-only farmland permanently retired is considered to reduce water depletions by 2.6 acre-feet per year.
The settlement also creates long-term monitoring requirements. New Mexico must adopt a Lower Rio Grande Water Management Plan within two years of the settlement becoming effective. That plan must include actions to maintain river delivery targets, stabilize aquifer levels, and address impacts from domestic wells.
Another major feature involves tracking groundwater conditions through “Indicator Wells” and monitoring whether aquifer levels are stable, rising, or declining. If certain thresholds are crossed, the United States and New Mexico must enter consultation processes to discuss corrective actions. However, the agreement still preserves New Mexico’s authority over day-to-day water administration decisions.
The settlement package (link to Special Master’s Report filed in February 2026) was originally filed in August 2025 after negotiations involving the states, the United States Bureau of Reclamation, and irrigation districts in both New Mexico and Texas. Background materials described the agreement as an effort to bring long-term stability and flexibility to the Lower Rio Grande while ensuring downstream deliveries continue reaching Texas users.
The Rio Grande supplies water to millions of people across Colorado, New Mexico, Texas, and Mexico. It also supports farming, local economies, and wildlife throughout the basin. Years of drought, declining river flows, and increasing groundwater pumping have placed growing pressure on the system.
With the Supreme Court’s approval now complete, the settlement moves from years of courtroom battles into the difficult phase of implementation, where water managers and communities will have to balance agriculture, groundwater use, river flows, and long-term sustainability in one of the Southwest’s most important river systems.
Source documents include the Supreme Court order issued May 26, 2026, and the Groundwater Settlement Agreement filed in Texas v. New Mexico, No. 141 Original (link to docket).
