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May water supply outlook reported

by Wyoming Livestock Roundup

On May 1, the U.S. Department of Agriculture’s (USDA) Natural Resources Conservation Service (NRCS) released the Wyoming Basin and Water Supply Outlook Report for May 2024, which analyzes snowpack, precipitation, streamflow and reservoir storage across the state of Wyoming. 

The report assesses the water supply outlook for the entire state of Wyoming, as well as individual basins including the Snake River, Madison Headwaters, Yellowstone River, Wind River, Big Horn River, Shoshone River, Powder River, Tongue River, Belle Fourche River, Cheyenne River, Upper North Platte River, Lower North Platte River, Laramie River, Sweetwater River, South Platte River, Little Snake River, Upper Green River, Lower Green River and Upper Bear River basins.

Snowpack and precipitation

According to NRCS, as of May 1, snow water equivalent (SWE) across Wyoming was 93 percent of median. 

The Laramie River Basin reported the highest SWE in the state at 105 percent of median, while both the Belle Fourche and Cheyenne River basins reported the lowest SWE at zero percent of median.

The Powder River Basin saw the highest amount of precipitation for the month of May at 126 percent of median, and the Lower Green River Basin saw the least amount of precipitation at 52 percent of median.


For May through September, USDA NRCS forecasts streamflow yields from all basins in Wyoming – except the Green River, Little Snake River and Cheyenne River basins – at 82 percent of median. 

For these three exceptions, median streamflow yields from May through July are predicted to report 86 percent of median in the Green River Basin, 99 percent of median in the Little Snake River Basin and 60 percent of median in the Cheyenne River Basin. 

According to USDA NRCS, streamflow yields for individual basins across Wyoming include the Powder River Basin at 67 percent of median, the Tongue River Basin at 71 percent of median, the Yellowstone River Basin at 84 percent of median, the Shoshone River Basin at 87 percent of median and the Lower North Platte River Basin at 91 percent of median. 

Additionally, the Upper North Platte River, Wind River, Big Horn River, Laramie River and Sweetwater River basins are forecast to yield 104 percent, 105 percent, 105 percent, 107 percent and 112 percent of median, respectively.

Reservoir storage

USDA NRCS further notes reservoir storage across the entire state of Wyoming averaged 106 percent of median.

All reservoirs reported numbers near or above median, with reservoirs in the Belle Fourche River Basin at 93 percent of median, reservoirs in the Lower North Platte River Basin at 97 percent of median and reservoirs in the Cheyenne River Basin at 100 percent of median.

Likewise, reservoirs in both the Wind River and Big Horn River basins reported numbers near median at 101 percent, and the Lower Green River Basin at 102 percent. 

Reservoirs in the Little Snake River Basin and the Upper Green River Basin, as well as the Buffalo Bill Reservoir on the Shoshone, had storage numbers above median, respectively reporting 112 percent, 117 percent and 118 percent of median. 

Reservoirs in the Upper North Platte River Basin reported the highest numbers at 121 percent of median. 

Hannah Bugas is the managing editor for the Wyoming Livestock Roundup. Send comments on this article to

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