Interstate Stream Commission

Lower Rio Grande

The Lower Rio Grande in New Mexico extends from Elephant Butte Dam to the border of Texas and Mexico. No perennial streams enter the Lower Rio Grande. However, the following large ephemeral streams flow directly into the Rio Grande:

• Las Animas Creek
• Cuchio Negro
• Percha Creek

Texas Vs New Mexico

New Mexico, Texas, Colorado and the United States filed a package of settlement agreements on August 29, 2025, with the Special Master in the U.S. Supreme Court case Texas v New Mexico and Colorado, Original Action No. 141 and requested dismissal of the case. The agreements, drafted with participation from relevant irrigation districts and water users in New Mexico and Texas, resolve over a decade of interstate litigation and allow the States and their water users to move forward in implementing sustainable long-term compliance with the Rio Grande Compact and  water resources management practices in the Lower Rio Grande. 

The U.S. Supreme Court’s Special Master will consider the package of agreements at a hearing in Philadelphia on September 29, 2025, and provide a recommendation to the U.S. Supreme Court. If approved by the Court, the settlement will provide certainty for water users in New Mexico and Texas and ensure that local communities and economies in the Lower Rio Grande can continue to thrive. 

Documents Filed with the U.S. Supreme Court’s Master: 

Lower Rio Grande Operations

Scheduled irrigation releases from Rio Grande Project reservoirs, Elephant Butte and Caballo Reservoirs, provide almost all of the surface water for irrigation in southern New Mexico and for irrigation districts in El Paso and Cuidad Juarez.

The Lower Rio Grande is mostly in Sierra and Doña Ana counties. Las Cruces is the largest city in the reach, and other towns include Truth or Consequences, Hatch, Radium Springs, and Anthony. The Lower Rio Grande includes portions of the Socorro/Sierra and the Lower Rio Grande Water Planning Regions.

The Rio Grande Project consists of Elephant Butte and Caballo Reservoirs, multiple diversion dams and several hundred miles of canals and drains within New Mexico and Texas. The project was designed to provide a reliable supply of surface water to specific lands in what are now Elephant Butte Irrigation District (EBID) and El Paso County Water Improvement District No. 1 (EPCWID1), plus 60,000 acre-feet/year of water to Mexico under the terms of a 1906 treaty. The allocation of Project water to New Mexico and Texas lands is approximately 57 percent and 43 percent respectively. Water is released from Caballo Reservoir during the irrigation season and diverted at the Percha, Leasburg and Mesilla Diversion Dams for use by New Mexico farmers in the Rincon and Upper Mesilla Valleys.

Water is also released from Caballo Reservoir and diverted for use by Texans in the Lower Mesilla Valley and at the Mesilla Diversion Dam for use by Texans in the El Paso Valley. Irrigation water is delivered to Mexico at the American Dam.