Alternative management paradigms for the future of the Colorado and Green Rivers

The Colorado River is among the most extensively managed river systems in the world. The river’s headwaters are within the Rocky Mountains in the United States. From there, it flows through the arid lands of the Colorado Plateau and the Basin-and-Range to its delta in northwestern Mexico. Here, the river is the only significant water supply in an otherwise starkly arid landscape and has long been called “America’s Nile.” It provides a critical water supply for nearly four million acres of irrigated land, municipal supplies for 30 million people located within and outside the basin, and more than 4,200 MW of hydropower generation capacity. The Colorado River and some of its tributaries also provide an existing or potential water supply for at least 15 Native American tribes. The river flows through seven National Wildlife Refuges, four National Recreation Areas, and five National Parks. Today, the annual consumptive uses and losses of streamflow in the basin typically exceed the amount of water available, and the river rarely flows into the Gulf of California. The impacts of climate change are likely to decrease future runoff and intensify droughts, thereby threatening current and future uses in the basin. Clearly, new ways of thinking about and managing the river need to be sought and implemented.