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:  October 18, 2023


 Upper Missouri Basin

September precipitation across the Upper Missouri Basin ranged from below to above average. Basin precipitation summaries for the Missouri Basin include: Milk St. Mary, 91 percent; Milk Canada, 83 percent; Lower Milk, 77 percent; above Toston, 153 percent; Toston to Ft. Peck, 159 percent. 

Of the four major irrigation reservoirs in Montana; Lima Reservoir had 179 percent average storage, Clark Canyon was holding 156 percent of average water, Gibson Reservoir had 55 percent of average stored water, and Fresno Reservoir had 53 percent of average stored water.

Yellowstone Basin 

Precipitation during September ranged from below to above average. The upper Yellowstone River Basin received 155 percent of average precipitation while the Lower Yellowstone River Basin reported 150 percent of average. The Bighorn Basin received 143 percent of average precipitation while the Wind River Basin received 92 percent of average. The Little Bighorn - Upper Tongue Basin received 129 percent of average and the Powder River had 174 percent of average precipitation.

Monthend storage at Boysen Reservoir was 107 percent of average. Stored water in Buffalo Bill Reservoir was 99 percent of average. Monthend storage was 101 percent of average at Bighorn Reservoir.


Platte Basin 

Precipitation during September in the Upper North Platte Basin was 49 percent of average.  In the Lower North Platte Basin, precipitation was 68 percent of average.  The North Platte Plains below Guernsy Reservoir had 111 percent.  The South Platte Mountains had 109 percent whereas the Plains had 80 percent of average September precipitation.

Stored water in the South Platte Basin was 134 percent of average on October 1.


September 2023  WY 2023
September 2023 Precipitation Percent of 1991-2020 Average WY2023 Precipitation as Percent of 1991-2020 Average
September 2023 Basin Mean Precipitation          WY2023 Basin Mean Precipitation
September 2023 MBRFC Basin Mean Precipitation      WY2023 MBRFC Basin Mean Precipitation