The U.S. Army Corps of Engineers began reducing the Gavins Point releases to the winter release rate on Nov. 24, marking the end of flow support for the 2020 Missouri River navigation season.
?Releases from Gavins Point Dam were reduced from 34,000 cubic feet per second to 17,000 cfs,? said John Remus, Chief of the Missouri River Water Management Division. ?Releases from Gavins Point will be adjusted this winter as needed to lessen the impacts of river ice formation on water intakes in the lower river.? Based on the Sept. 1 System storage, Gavins Point Dam winter releases will be at least 17,000 cfs.
As the colder, winter temperatures enter the basin, USACE will closely monitor Missouri River ice conditions between the System reservoirs and downstream of Gavins Point Dam for potential ice jams that could impact river stages and water intakes.
Runoff in the upper Missouri River Basin above Sioux City, Iowa, was 1.2 million acre-feet during November, 116% of average. The 2020 calendar year runoff forecast is 30.6 MAF, 119% of average. The average annual runoff is 25.8 MAF. The total volume of water stored in the Missouri River mainstem reservoirs is currently 56.3 million acre-feet, occupying 0.2 MAF of the 16.3 MAF combined flood control storage zones. System storage is forecast to reach the base of the combined flood control storage zone in mid-to late-December.
Releases from Fort Peck Dam were increased to 10,500 cfs on Dec. 3 and will be increased to 11,500 cfs in January and February. Releases from Garrison Dam were increased to 16,000 cfs on Dec. 2. Releases from Garrison Dam are typically set near 16,000 cfs prior to the river freeze-in to reduce the risk of ice-induced flooding in the Bismarck, N.D., area. Releases will remain at that rate in December, and conditions permitting, will be gradually increased to 20,500 cfs following the formation of a stable river ice cover at Bismarck. Releases at Fort Peck and Garrison dams are being adjusted as part of balancing storage in the upper reservoirs.
To view the detailed three-week release forecast for the mainstem dams, go to http://go.usa.gov/xVgWr.
