Missouri River basin’s below-normal precipitation leads to lower runoff forecast; reduced Gavins Point releases

Staff Writer
Nebraska City News-Press
The Upper Missouri River basin has experienced below-normal precipitation since January. This map shows the precipitation departure from normal for the last 180 days from May 7, 2020. The map and data are generated by the National Weather Service's Advanced Hydrologic Prediction Service. The location of upper basin Missouri River mainstem dams has been spotlighted.

Gavins Point releases were to be reduced to 33,000 cubic feet per second (cfs) on Friday, May 8, following a reduction in forecast 2020 upper basin runoff.

Since January, precipitation in the upper basin has been well below normal, which has led to a reduction in the runoff forecast. Some areas of the Dakotas received less than half of their normal precipitation during the first four months of 2020.

The 2020 calendar year upper basin runoff forecast has been reduced to 32.2 MAF. “This is still an above average runoff forecast. The upper basin runoff for the remainder of 2020 depends on mountain snowmelt and rain events,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. Although this forecast is a reduction of 3.3 MAF from the April 1 forecast, it is still in the top 25 percent of the 122 years of runoff record. Average annual runoff for the upper basin is 25.8 MAF. The runoff forecast is updated on a monthly basis, and more often if basin conditions warrant.

Soil moisture conditions continue to be wet in much of the upper Missouri River Basin, which increases the potential for above average runoff in the upper basin. The potential for flooding remains, particularly in the lower river due to continued high river stages on many of the uncontrolled tributaries downstream of the Missouri River Mainstem Reservoir System. When possible, additional adjustments to Gavins Point releases may be made to offset tributary flows from heavy rain events. “I encourage all interested parties to check the Corps’ Missouri River Basin Water Management and the National Weather Service websites on a daily basis for the most up-to-date information on System conditions and forecasted river stages,” said Remus.

For more information, visit https://www.nwd.usace.army.mil/Media/News-Releases/Article/2179600/missouri-river-basins-below-normal-precipitation-leads-to-lower-runoff-forecast/