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:  July 20, 2023


 Upper Missouri Basin

June precipitation across the Upper Missouri Basin ranged below to above average. Basin precipitation summaries for the Missouri Basin include: Milk St. Mary, 73 percent; Milk Canada, 94 percent; Lower Milk, 126 percent; above Toston, 148 percent; Toston to Ft. Peck, 155 percent. 

Of the four major irrigation reservoirs in Montana; Lima Reservoir had 131 percent average storage, Clark Canyon was holding 127 percent of average water, Gibson Reservoir had 94 percent of average stored water, and Fresno Reservoir had 103 percent of average stored water.

Yellowstone Basin 

Precipitation during June was above average. The upper Yellowstone River Basin received 207 percent of average precipitation while the Lower Yellowstone River Basin reported 229 percent of average. The Bighorn Basin received 284 percent of average precipitation while the Wind River Basin received 312 percent of average. The Little Bighorn - Upper Tongue Basin received 291 percent of average and the Powder River had 208 percent of average precipitation.

Monthend storage at Boysen Reservoir was 114 percent of average. Stored water in Buffalo Bill Reservoir was 102 percent of average. Monthend storage was 111 percent of average at Bighorn Reservoir.


Platte Basin 

Precipitation during June in the Upper North Platte Basin was 125 percent of average.  In the Lower North Platte Basin, precipitation was 192 percent of average.  The North Platte Plains below Guernsy Reservoir had 127 percent.  The South Platte Mountains had 199 percent whereas the Plains had 201 percent of average June precipitation.

Stored water in the South Platte Basin was 110 percent of average on July 1.


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