Difficult policy decisions are needed to stabilize the Colorado River’s flow

The Colorado River – a crucial source of water in the southwestern United States – is undergoing a basin-wide water supply crisis due to ongoing drought and a history of poor water management policies. In a Policy Forum, Kevin Wheeler and colleagues argue that drastic measures and difficult decisions are needed to prevent further decline and to avoid severe outcomes. Flowing from the Rocky Mountains of Colorado to the Gulf of California in northwestern Mexico, the Colorado River supplies water to more than 40 million people, including those in major U.S. cities like Los Angeles, Phoenix, and Las Vegas. What’s more, a substantial portion of the river’s water is used to irrigate nearly 5.7 million acres of agriculture. However, climate change and mismanagement have led to severe declines in the river’s output – by the end of 2022, it’s estimated that the combined storage of Lake Powell and Lake Mead, the two largest reservoirs in the U.S., which are fed by the river, will fall to 25% of their capacity. Today, the river’s entire flow is diverted along its 1,400 mile-long course, and in its lower reaches, only 10% of the natural flow reaches Mexico. Rarely does the river ever flow to the ocean. Wheeler et al. discuss the policy and climate conditions that have led to the drying of the river, which include the far-reaching repercussions of politically separating the river into an Upper and Lower basin and the ongoing 23-year-long “Millennium Drought.” The authors modeled 100 possible scenarios and management strategies and found that drastic political measures will likely be required to stabilize the river’s resources, particularly those that limit the amount of water used by all stakeholders. The findings highlight the difficulties and pressures that decision-makers will face in the coming years. “Our results show that although current policies are inadequate to stabilize the Colorado river if the Millennium Drought continues, various consumptive use strategies can stabilize the system. However, these measures must be applied swiftly,” write the authors. “Although these concessions by both basins may seem unthinkable at present, they will be necessary if recent conditions persist.”