Here’s the release from the NRCS (Brian Domonkos):
An exceptionally dry April, along with warmer mountain temperature exacerbated already dry conditions in much of Colorado. Precipitation in April ranged from a high of 83 percent of average in the South Platte River Basin to as low as 29 percent of average in the combined San Miguel-Dolores-Animas-San Juan river basin. NRCS Hydrologist Joel Atwood notes, “Many SNOTEL sites reported record low precipitation for April west of the Continental Divide. Snowpack has also declined in all basins except the South Platte, due to higher temperature and below-average precipitation.” As of May 9th, all basins in the state have snowpack below 80 percent of median except the South Platte river basin, which has 102 percent of median snowpack.
Statewide reservoir storage declined by a percentage point over last month, where all basins except the South Platte river basin saw a decline in relative storage. The combined Yampa-White-North Platte and the South Platte river basins ended April with above-average storage at 106 and 101 percent of average, respectively. On the low end, the combined San Miguel-Dolores-Animas-San Juan and the Arkansas river basins ended April with 57 and 69 percent of average reservoir storage, respectively.
Recent precipitation that has helped improve water supply in the South Platte river basin has had little impact on the rest of the state. Dry conditions have persisted in much of the state since last summer, and a dry April only compounded current drought conditions. NRCS Hydrologist Atwood continued to comment that “With much of the snowpack in many basins already melted out, persistent dry soil conditions, and little hope for substantial precipitation moving into summer, runoff volumes will continue to be meager.” All basins west of the continental divide are forecasted to have streamflow volumes between 34 and 73 percent of average. The South Platte river basin, which has the best water supply outlook in the state, has streamflow volume forecasts range from 90 to 104 percent of average.
* For more detailed information about May 1st mountain snowpack refer to the May 1, 2021 Colorado Water Supply Outlook Report. For the most up to date information about Colorado snowpack and water supply related information, refer to the Colorado Snow Survey website.