Missouri Basin River Forecast Center
Water Supply Statement
Issued in cooperation with the Natural
Resources Conservation Service
Issued: November 23, 2020
Upper Missouri Basin
October precipitation across the Upper Missouri Basin was above average. Basin precipitation summaries for the Missouri Basin include: Milk St. Mary, 123 percent; Milk Canada, 123 percent; Lower Milk, 103 percent; above Toston, 100 percent; Toston to Ft. Peck, 170 percent.
Of the four major irrigation reservoirs in Montana; Lima Reservoir had 145 percent average storage, Clark Canyon was holding 98 percent of average water, Gibson Reservoir had 45 percent of average stored water, and Fresno Reservoir had 39 percent of average stored water.
The major hydroelectric reservoirs in Montana (Canyon Ferry and Fort Peck), had monthend storage in the average to above average range; 94 and 116 percent of average water, respectively.
Precipitation during October was average to above average. The upper Yellowstone River Basin received 193 percent of average precipitation while the Lower Yellowstone River Basin reported 126 percent of average. The Bighorn Basin received 92 percent of average precipitation while the Wind River Basin received 53 percent of average. The Little Bighorn - Upper Tongue Basin received 168 percent of average and the Powder River had 108 percent of average precipitation.
Monthend storage at Boysen Reservoir was 95 percent of average. Stored water in Buffalo Bill Reservoir was 121 percent of average. Monthend storage was 97 percent of average at Bighorn Reservoir.
Precipitation during October in the Upper North Platte Basin was 59 percent of average. In the Lower North Platte Basin, precipitation was 47 percent of average. The North Platte Plains below Guernsy Reservoir had 41 percent. The South Platte Mountains had 52 percent whereas the Plains had 39 percent of average October precipitation.
Stored water in the South Platte Basin was 95 percent of average on November 1.