Submitted Photo The shaded blue in these charts indicates current snowpack water content in the mountains and plains that comprise the Missouri River drainage above Lake Sakakawea. The red line is the 25-year average.

Indications are there won’t be much of a snowmelt runoff into the upper reaches of the Missouri River Basin this year. The U.S. Army Corps of Engineers issued their monthly update Thursday, saying that current conditions favor a below-normal runoff season.

“Despite runoff being slight above average in January, we expected 2021 runoff to be below average,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division. “Both plains snowpack and mountain snowpack continue to lag behind season averages, and soil moisture continues to be much drier than normal.”

The Corps’ Feb. 2 report on mountain snowpack water content confirms Remus’ view. Snowpack thus far in the winter season is tracking closer to the 25-year low than it is to average. As of Feb. 1, based on the long-term average, 60% of the typical snowpack accumulation season is complete. Mountain snowpack normally peaks about April 15.

Based on a variety of conditions, such as snowpack, soil moisture, and long-range weather outlooks, a Missouri Basin runoff of 22.9 million acre feet, or 89% of the 25.8 maf historic average, is currently forecast for 2021. That is a decrease of 0.2 maf from the January outlook.

According to the Corps, the Jan. 31 mountain snowpack above Fort Peck reservoir in Montana was 78% of average and the snowpack from Fort Peck to Garrison reservoir, Lake Sakakawea, was 79% of average. There’s not much chance of those percentages increasing, at least not through the middle of February. The National Weather Service lists only a slight chance of greater than normal precipitation throughout the Missouri River Basin the next two weeks.

Based on current conditions throughout the basin, Lake Sakakawea is projected to reach a peak elevation this year of 1,842.1 feet at the end of July. Sakakawea peaked at 1,844.5 feet in 2020. All three upper Missouri reservoirs, Fort Peck, Garrison, and Lake Oahe, are below or very near the bottom of their annual flood control zones.

“System storage remains slightly below the base of the annual flood control zone,” explained Remus, adding that system was in “good position” for 2021 to meet all authorized purposes, including flood control.