JACKSON, Wyo. — The Wyoming water supply outlook this spring looks right on the mark. Too much stored water could lead to flooding; too little would further plunge the state into drought.

According to data compiled by the National Weather Service and released in a report May 8, April 2020 precipitation totals across Wyoming were 75-85 percent of average. Precipitation numbers varied between 135 percent of normal over the Snake River Basin (Jackson, et al) to 60-65 percent of average over the Powder and Belle Fourche Drainages (northeastern Wyoming).

Over the current water year (October 2019 through April 2020), precipitation across Wyoming was near average.

Mountain snowpack across Wyoming was 85-95 percent of median by early May. Snowpack “water” numbers and/or SWEs were the highest across basins in northwestern Wyoming—varying between 105 to 115 percent of median. SWEs across basins in south-central through southwestern Wyoming (Sweetwater, Upper Bear, and Lower Green Basins) were below 85 percent of median.

Snowmelt across the state is occurring at right about average. Near normal (95-105 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, Shoshone, and Snake River Watersheds. 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 75-85 percent of capacity in early May. Reservoir storages across Wyoming remained above average at 105-115 percent for May.