Study analyzes future Colorado River flows post-2026

A new analysis using data from the Coupled Model Intercomparison Project examines potential climate impacts on Colorado River flows through 2050, as operating guidelines for water management are set to expire in 2026. The study focuses on flows at Lees Ferry, the gauge through which 85% of the river’s flow passes, and evaluates the likelihood of water resource recovery from low flows observed between 2000 and 2020. 

The study highlights the importance of precipitation variability in determining future river flows. According to the projections, precipitation in the upper Colorado River basin is expected to increase by 5% to 7% due to climate change during the period from 2026 to 2050. This increase in precipitation is projected to counteract some of the flow reductions caused by basin-wide warming. The extent to which this increase compensates for the effects of rising temperatures will depend on the river’s sensitivity to temperature changes. 

The analysis shows that projected flows at Lees Ferry could vary significantly, with potential changes ranging from a 25% decrease to a 40% increase by mid-century. This range is driven largely by decadal variability in precipitation, which is shown to have a greater impact on river flow than temperature alone. The projections indicate that both extremely low and high flows are more likely during the study period. 

When flows are modeled based on initial drought conditions similar to those experienced from 2000 to 2020, the report finds that water resource recovery is possible. However, there remains a risk of further declines in river flows, particularly if temperature increases are not offset by precipitation gains.