For most of the last two years, monthly precipitation amounts have been below average within the Colorado River District. As of April 30, the snow water equivalent is well below average across the Western Slope with the Colorado basin at 72% of average, the Gunnison at 62% and the Yampa & White at 72%.
In addition to the below-average seasonal snowpack, the temperature and precipitation model forecasts from the National Weather Service’s Climate Prediction Center are predicting a hot and dry summer with above-average temperatures across most of the southwest. Forecasters also predict below-average precipitation, particularly in the Upper Colorado River Basin. Most of the Colorado River Basin is currently in extreme or exceptional drought conditions.
Adding insult to injury, low soil moisture will adversely impact runoff. Models from the Colorado Basin River Forecast Center suggest the majority of the Upper Colorado River Basin has such low soil moisture that it will require up to 12 inches of water to reach saturation. This means that most of the snowpack is absorbing into the soils and not turning into runoff. With the sizable reservoir drawdowns from last year, very few reservoirs are likely to fill in the upcoming water year. This soil moisture deficit presents a significant challenge to refilling the Colorado River storage system, especially the lower, larger facilities, like Lakes Powell and Mead.
The U.S. Bureau of Reclamation’s mid-term modeling forecasts project this water year to be below average, with inflow into Lake Powell at about 5.13 million acre-feet, less than 47% of the long-term average. Furthermore, Reclamation projects that Lake Powell will end the water year near 3,557.03 feet elevation, holding about 8.10 million acre-feet in storage, which is 33% of its capacity.