Exceptional drought conditions across W. Slope

RBC | April 2021 was “exceptionally dry” according to the latest statistics from the USDA’s National Resource Conservation Service. NRCS Hydrologist Joel Atwood noted “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.”

According to the U.S. Drought monitor, the region is experiencing D4 drought level classified as “exceptional drought,” the highest level under extreme (D3), severe (D2), moderate (D1) and abnormally dry (D0).

Despite the well-below-average precipitation levels in the Yampa–White River Basin last month, reservoir storage is sitting at 106% of average. NRCS’ latest report notes however that consistent dry conditions since last summer combined with last month’s lack of precipitation compounded drought conditions. Atwood said, “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.” Streamflow volumes for all basins west of the Continental Divide are projected between 34 and 73 percent this summer.

With these statistics and projections in mind, the local White River Alliance this week heard from Colorado Parks and Wildlife’s Northwest Regional Water Specialist David Graf on the topics of a potential for expansion of the Lake Avery Reservoir at the headwaters of the White River and “some lease options CPW is considering for 2021.”

In an email sent out prior to the presentation, WRA member Dr. Bob Dorsett questioned the viability of increased storage as a solution “if there’s no water to store.” Dorsett also reiterated NRCS data points, noting that the White River peaked on May 2 at about 700 cfs and the Yampa peaked May 4 at about 3500 cfs. “The peaks occurred about six weeks ahead of the historical normal, and both rivers are running near historical lows,” wrote Dorsett.

He also highlighted the lack of “reserve moisture” in the soil which means much of the runoff that would normally make its way into rivers is being absorbed along the way. “Burro Mountain is reporting no snowpack remaining,” said Dorsett, adding “In a normal year it should have about 10 inches of water equivalent remaining.”

Severe to exceptional drought conditions persist across much of the state, with many Western Slope counties seeing the most significant decreases in precipitation and available water in storage. As an example, SNOTEL sites in the San Juan region are reporting just 40% median snowpack.

Statewide, apart from the South Platte River Basin (which has 102% median snowpack), all other basins are reporting less than 80% average snowpack. Snowpack in the Yampa/White River basin is at 73% of median for this time of year.

You can read more detailed information on snowpack in NRCS’ May 1, 2021 Colorado Water Supply Outlook Report. The most up to date information about Colorado snowpack and water supply is at the Colorado Snow Survey website https://www.nrcs.usda.gov/wps/portal/nrcs/main/co/snow/

By LUCAS TURNER | lucas@ht1885.com