Water Levels To Remain Steady At Dam
Below-average precipitation and dry soil conditions persist in the upper Missouri River Basin above Sioux City, Iowa (upper Basin).
The updated 2021 upper Basin runoff forecast is 17.9 million acre-feet (MAF), 69 percent of average. If realized, this runoff amount would be in the 22nd driest year in the upper Basin since 1898. The May upper Basin runoff was 64 percent of average. May runoff in the Fort Peck and Garrison reaches, where much of the upper Basin runoff from mountain snowmelt originates, was 60 percent and 68 percent of average, respectively. “Per our June 1 upper Basin forecast, we expect runoff to continue to be well-below average through the summer and fall,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division.
“The June 1 reservoir studies indicate the navigation service level, based on the July 1 System storage check, will be reduced by approximately 1,000 cubic feet per second (cfs) for the second half of the navigation season. The studies also indicate that the winter release from Gavins Point will be at minimum levels, which is 12,000 cfs.”
System storage is currently 55.2 MAF, 0.9 MAF below the base of the Annual Flood Control and Multiple Use Zone. System storage is expected to remain in the Carryover Multiple Use Zone during 2021.
Mountain Snowpack: Mountain snowpack in the upper Basin was below the June 1 average and is melting rapidly. The mountain snowpack peaked above Fort Peck in late March at 86 percent of average, while the mountain snowpack in the Fort Peck to Garrison reach peaked in late April at 96 percent of average. Mountain snowpack normally peaks near April 15.
Fort Peck Dam: Average releases past month – 8,400 cfs; Current release rate – 9,500 cfs; Forecast average release rate – 9,500 cfs; End-of-May reservoir level – 2233.0 feet’ Forecast end-of-June reservoir level – 2233.1 feet Releases will be maintained at 9,500 cfs through August.
