Missouri Basin runoff increased

More water for Lake Sakakawea

There’s plenty of water on the way for the state’s largest reservoir. The latest information compiled by the U. S. Army Corps of Engineers shows a significant increase in the amount of runoff expected to enter the Missouri River Basin in the coming months.

The Corps February outlook called for 26.4 million acre feet of runoff. The March outlook has increased to 29.0 maf, a level the Corps says is 115 percent of average. To put the number in perspective, consider that the current mountain snowpack water content is tracking above 2011 levels, the year when high water resulted in the opening of the release gates at Garrison Dam for this first time in the history of the facility.

While this year’s reservoir conditions are much different than in 2011, namely the amount of flood storage available in the Missouri River system to adequately handle the heavy flows, the numbers are still attention getting. Lake Sakakawea is now projected to reach a peak elevation of 1,846 this summer, a foot more water than was expected a month ago. Overflow at Lake Sakakawea is 1,854 feet.

The latest mountain snowpack analysis shows a snow water equivalent above Fort Peck Reservoir in Montana to be 130 percent of average. The Yellowstone River reach, or Fort Peck to Garrison, is currently about 136 percent of average. Normally by March 1 about 79 percent of the peak snow water content has occurred in both reaches.

Snowmelt runoff information was compiled prior to the latest storm that dumped up to a foot of snow over portions of Montana and North Dakota. Although the snowfall is not generally expected to have much of an effect on overall runoff into the Missouri River Basin, the storm totals will be factored into the next outlook which will be issued in early April.