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Corps to increase releases from Gavins Point Dam

May 10, 2018 GMT

OMAHA — Releases from Gavins Point Dam and other Missouri River reservoirs will remain at above-average levels for the coming months to disperse runoff that remains above normal, the U.S. Army Corps of Engineers said Tuesday.

Releases from Gavins Point near Yankton, South Dakota, were increased to 37,000 cubic feet per second in early May and will gradually be increased to 42,000 cfs and possibly higher.

The higher releases are in response to an updated 2018 runoff forecast of 33.2 million acre feet in the Missouri River basin above Sioux City, Iowa. That forecast level, 131 percent of average, was raised by 3 MAF in April because of continued accumulation of mountain snowpack and the delayed melt of plains snow in early April. Mountain snowpack ranged from 129 percent to 135 percent of average.

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To put the runoff forecast in perspective, runoff in 2011, when damaging flooding was widespread in the river valley, was 61 MAF.

As of May 1, storage in the six Missouri River reservoirs was 60.6 MAF, occupying 4.5 MAF of the 16.3 MAF flood-control zone.

“More than 70 percent of the system’s flood storage remains available to capture runoff from the mountain snowmelt and spring and summer rainfall events,” John Remus, chief of the corps’ Missouri River Basin Water Management Division, said in a news release.

Remus said reservoir releases could be adjusted higher or lower depending on conditions downstream of Gavins Point.