Little rise for Lake Sakakawea

Lake Sakakawea will rise only slightly this summer, maybe not even enough to notice.

That’s according to the most recent runoff outlook issued by the U.S. Army Corps of Engineers.

The April outlook projects Lake Sakakawea to peak this summer at just over 1,831 feet. The reservoir stood at 1827.7 feet Monday and is projected to end the month of April at 1,829.4 feet. However, based on the Corps’ three-week forecast, it appears likely that Sakakawea will end April at less than than 1,829 feet. Runoff, which has yet to get under way, and rainfall could change those projections.

A summer rise of 10 feet to 20 feet is not unusual for Lake Sakakawea, but this summer is not setting up to be anything close to a normal runoff season. The Mountain Snowpack Report for April 1 says the snowpack is 90 percent of normal above Fort Peck Dam in Montana and only 84 percent of normal in the reach from Fort Peck to Sakakawea. The former is generally considered the Missouri River drainage and the latter the Yellowstone River drainage. Both rivers greatly influence the amount of water that enters Lake Sakakawea.

The mountain snowpack traditionally reaches its peak at mid-April, but has been trending slightly downward since the beginning of the year. As always, there remains several variable that could substantially change the amount of runoff – lower or higher. Factors include soil moisture content, temperatures during the melt season and the amount of rainfall received over portions of the drainage.

According to the Corps, this year’s Missouri River Basin runoff is now expected to total 20.5 million acre feet. The long-term average is 24.8 maf. The projected levels for Lake Sakakawea should not create any difficulties for access ramps to the lake. However, if Sakakawea should drop much lower than what is currently projected, boat ramp access will begin to become an issue.