Rethinking How the United States and Mexico Share the Colorado River

Authors

• Eric Kuhn
• Anne Castle, University of Colorado, Boulder
• Carlos de la Parra, Centro Luken de Estrategias en Agua y Medio Ambiente
• John Fleck, University of New Mexico
• Jack Schmidt, Utah State University
• Kathryn Sorensen, Arizona State University
• Katherine Tara, University of New Mexico

Document Type

Working Paper

Publication Date

3-26-2026

Abstract

Since 1945, the United States and Mexico have managed common interests on their two largest shared rivers systems, the Colorado and the Rio Bravo/Rio Grande, under the terms of the 1944 international treaty that was designed from the beginning with tools to adapt to changing hydrologic and societal conditions. A recent emergency agreement on the Rio Bravo/Rio Grande illustrates what is possible, and with old river management rules on the Colorado both within the United States and between the United States and Mexico about to expire, we are at a moment of opportunity for meaningful change. The core problem on the Colorado River, which we address in the analysis that follows, arose from decisions made in the first half of the 20th century to allocate fixed volumes of water. As usage patterns and hydrology change in the 21st century, fixed volumes no longer work. A shift to a percentage-based split between the United States and Mexico on the Colorado River, based on the river's actual natural flow, would provide a solid foundation for the two countries' joint management of the Colorado in the decades to come.

Recommended Citation

Kuhn, Eric; Anne Castle; Carlos de la Parra; John Fleck; Jack Schmidt; Kathryn Sorensen; and Katherine Tara. "Rethinking How the United States and Mexico Share the Colorado River." (2026). https://digitalrepository.unm.edu/uc_traveling_wilburys/7