OMAHA -- The U.S. Army Corps of Engineers has enacted water conservation measures in the Missouri River reservoir system in response to continued drought conditions in the river's basin above Sioux City.
The corps announced Thursday that water releases from Gavins Point Dam near Yankton, South Dakota, have been decreased from 30,500 cubic feet per second to 28,500 cfs, reducing the river's flow support for downstream navigation.
"The intermediate service level is a necessary water conservation measure to ensure authorized purposes will be served in the short and long term," John Remus, chief of the corps’ Missouri River Basin Water Management Division, said in a news release.
Runoff into the river's upper basin was 52% of average in June. The corps on Thursday forecast 2021 runoff at 15.6 million acre-feet, 60% of average. That total would be the 10th driest year in the basin since 1898. The average annual runoff is 25.8 MAF.
As of Thursday, reservoir storage throughout the system was at 55.2 MAF, 0.9 MAF below the base of the annual flood control zone, and storage is expected to continue to decline.
Winter releases from Gavins Point likely will be at the minimum level of 12,000 cubic feet per second, the corps said.
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Precipitation in Montana and the Dakotas has been well below normal since October, and mountain snowpack that melts and feeds the Missouri River in the late spring and early summer also was below normal levels. Snowpack melted out in mid to late June, the corps said, several weeks earlier than normal.