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Mountain snowpack water content in the Missouri River basin of western Montana has reached levels approaching some of the highest totals on record. In fact, the latest measurements provided by the U.S. Army Corps of Engineers are eerily close to the peak measurements of 2011, which was a historic flood year for the Missouri River system.
There though, the similarities end.
There is ample storage within the Missouri River reservoir system to easily handle the predicted runoff. Also, the snowpack is already reversing its upward trend. Indications are the build-up of snow in the mountains has reached its peak and is regressing under the warmer temperatures of recent days.
The projected amount of runoff into the Missouri River system, which includes Lake Sakakawea, has increased each month so far this year along with the snowpack. The April 1 forecast reached 30.2 million acre feet. The historic average for the system is 25.3 maf. When the new runoff outlook is issued later this week it is expected to contain only a slight increase.
A major difference in runoff this season as compared to many years in the past, including last year, is that runoff effecting Lake Sakakawea arrived somewhat early.
"The big difference now is that we came up early due to snowpack in Montana," said Todd Lindquist, Corps project manager, Riverdale. "The plains snowpack is gone. A lot of that actually soaked in because of pretty dry conditions."
Lake Sakakawea was at 1,842.27 feet Monday. The April first outlook anticipated an end of month elevation of 1,839.8 feet. Lindquist says, based on current conditions, he expects Lake Sakakawea to perhaps reach a level a 12 to 18 inches higher than last year. The 2017 high for the reservoir was about 1,846.6 feet.
Mountain snowpack above Fort Peck, Montana was measured at 143 percent of normal last week. A new runoff forecast for the Missouri River basin released later this week should provide a very good guideline of what to expect for snowmelt in the coming days.
Lake Sakakawea primarily remained frozen Monday with open water along some shoreline areas. The latest date the large reservoir was declared "ice free" by the Corps was May 17, 1979.