The Colorado River provides water to over 30 million people and four million acres of irrigated land across the southwestern United States. The watershed, which includes seven states, parts of Mexico, and 29 federally-recognized Tribes, is one of the most extensively managed river systems in the world. Yet the varied policies governing the watershed, termed the Law of the River, are becoming increasingly outdated in the face of 21st century climate change and modern water demands. In early 2021, federal and state agencies resumed previously paused meetings with stakeholders to renegotiate the terms of Colorado River management policies. 

To aid in this effort, the Center for Colorado River Studies released a white paper describing how climate change is projected to affect future water supplies in the Colorado and Green Rivers. Southwest CASC affiliated researchers and co-authors compared future water supplies, estimated using multiple climate futures accounting for expected droughts and warming in the region, to future water use projections reported by the Upper Basin Water Commission. They found that projected future water use will likely outstrip future water supply. Yet they concluded that these future water use projections, the foundations of many watershed policies, overestimate actual water use in the region. They propose a wide variety of alternative management paradigms for managers to consider for adopting innovative, sustainable water management practices.  

This work was supported in part by the Southwest CASC project “The Impacts of Climate Change and Water Supply Management on Fish in the Colorado River.”