Bull Lake, Boysen Reservoirs below average capacity for early April

Wyoming NOAA hydrologist Jim Fahey shares the April 2020 Wyoming water supply outlook.

Below are the highlights from the complete report that can be viewed here: Water Supply Report



…Wyoming March 2020 precipitation was 80 to 90 percent of average…

…Current water year precipitation is averaging 95 to 105 percent of normal across Wyoming…

…Mountain snowpack across Wyoming is still 105 to 115 percent of median…

Near normal (95 to 110 percent) snowmelt streamflow volumes are still expected across several major basins in Wyoming…


…Wyoming reservoirs continue to average 75 to 80 percent of capacity in early April…


March 2020 precipitation totals across Wyoming were 80 to 90 percent of average. Precipitation numbers varied between 145 percent of normal over the South Platte River (southeast  Wyoming) and Upper Yellowstone (northwest Wyoming) Drainages; to near 45 percent of average over the Big Horn and Tongue Basins (north-central Wyoming).  Current water year (October 2019 – March 2020) precipitation across Wyoming was 95 to 105 percent of average.


Mountain snowpack across Wyoming was 105 to 115 percent of the median by early April. Snowpack “water” numbers and/or SWEs were the highest across basins in north-central through western Wyoming—varying between 115 to 125 percent of median.  SWEs across basins in south-central Wyoming (Sweetwater Basin) and eastern Wyoming were 70 to 80 percent of median.

Near normal (95 to 110 percent) snowmelt streamflow volumes are still expected across several major basins in Wyoming. Above-average snowmelt streamflow volumes are expected across portions of the Laramie, Upper North Platte, Powder, and Snake (Salt)  Watersheds. The Sweetwater and Upper Green Basins, as well as portions of the Little Wind River Drainage, are still forecasted to have below-normal streamflow volumes during the upcoming snowmelt season.

Wyoming reservoirs are averaging 75 to 80 percent of capacity in early April. Reservoir storages across Wyoming remained above average at 120 to 130 percent for April.

h/t NOAA via Jim Fahey

Other hydrological information for Wyoming can be found at the NOAA hydrology website

Monthly Wyoming Hydrologic Summary and Graphics: (updated monthly around the 15th of every month)

Wyoming Drought Information Page: (updated at least once a month)

Wyoming Graphical Water Supply Outlook: (updated by the 10th of every month—January-June)

Wyoming Average Precipitation by Basin: (updated monthly)

Wyoming Spring Snowmelt Runoff Flood Potential Graphic: (updated around the 20th of the month—February-April—sometimes May)

Current and Forecast Wyoming Streamflows and/or River Stages:


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