Reservoir inflows in the upper Missouri River Basin (above Sioux City, Iowa) were below average last month (March 2021).
The updated 2021 upper Basin runoff forecast is 21.3 million acre-feet or 83% of average.
John Remus is the chief of the US Army Corps of Engineers’ Missouri River Basin Water Management Division. He says abundant precipitation fell during March below Sioux City, IA; however, March precipitation was less than 50% of normal over much of the upper Basin.
Remus says because of the lack of plains snowpack this winter, below-average mountain snowpack and dry upper Basin conditions, the Corps expects upper Basin runoff to be below average. He says the upper Basin runoff forecast is based on soil moisture conditions, plains snowpack, mountain snowpack and long-term precipitation and temperature outlooks.
The Oahe Dam reservoir at Pierre/Fort Pierre was at elevation 1607.2 at the end of March, up just over half of a foot (0.6 foot) from February. The elevation is forecast to be at the same level– 1607.2 feet– at the end of April.
The forecast reservoir releases and elevations are not definitive. Additional precipitation, lack of precipitation or other circumstances could cause adjustments to the reservoir release rates. The System is positioned to serve all Congressionally authorized purposes during 2021, including flood control, navigation and water supply.
Image credit US Army Corps of Engineers spring public meeting slide presentation.
Image credit US Army Corps of Engineers spring public meeting slide presentation.
Image credit US Army Corps of Engineers spring public meeting slide presentation.
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