National Weather Service United States Department of Commerce

Missouri Basin River Forecast Center
Water Supply Statement
Issued in cooperation with the Natural
Resources Conservation Service
Issued:  September 20, 2023


 Upper Missouri Basin

August precipitation across the Upper Missouri Basin was near to above average. Basin precipitation summaries for the Missouri Basin include: Milk St. Mary, 184 percent; Milk Canada, 86 percent; Lower Milk, 87 percent; above Toston, 206 percent; Toston to Ft. Peck, 90 percent. 

Of the four major irrigation reservoirs in Montana; Lima Reservoir had 189 percent average storage, Clark Canyon was holding 152 percent of average water, Gibson Reservoir had 30 percent of average stored water, and Fresno Reservoir had 71 percent of average stored water.

Yellowstone Basin 

Precipitation during August was above average. The upper Yellowstone River Basin received 175 percent of average precipitation while the Lower Yellowstone River Basin reported 188 percent of average. The Bighorn Basin received 169 percent of average precipitation while the Wind River Basin received 235 percent of average. The Little Bighorn - Upper Tongue Basin received 167 percent of average and the Powder River had 169 percent of average precipitation.

Monthend storage at Boysen Reservoir was 103 percent of average. Stored water in Buffalo Bill Reservoir was 101 percent of average. Monthend storage was 98 percent of average at Bighorn Reservoir.


Platte Basin 

Precipitation during August in the Upper North Platte Basin was 149 percent of average.  In the Lower North Platte Basin, precipitation was 185 percent of average.  The North Platte Plains below Guernsy Reservoir had 129 percent.  The South Platte Mountains had 136 percent whereas the Plains had 142 percent of average August precipitation.

Stored water in the South Platte Basin was 133 percent of average on September 1.


August 2023  WY 2023
August 2023 Precipitation Percent of 1981-2010 Average WY2023 Precipitation as Percent of 1981-2010 Average
August 2023 Basin Mean Precipitation          WY2023 Basin Mean Precipitation
August 2023 MBRFC Basin Mean Precipitation      WY2023 MBRFC Basin Mean Precipitation