The Army Corps of Engineers say they saw record runoff in the upper Missouri River Basin above Sioux City in March. They said they had 11 million acre feet (MAF) for the month when the average is 2.9. The previous record was set in 1952 at 7.3 MAF.
U.S. Army Corps of Engineers Chief John Remus for the Missouri River Basin Water Management Division said that the record runoff has altered their forecast of the upper basin for the year.
“Our runoff forecast increased to 38.2 MAF, which is 151 percent of normal. The March runoff was nearly 4 times the average. Runoff in the Fort Randall Dam to Gavins Point Dam reach was nearly twice the record highest March runoff. March runoff in the Gavins Point to Sioux City reach was more than that reach typically sees during a year,” Remus said.
Releases at Gavins Point are currently 39,000 cfs. The Corps plans to increase the releases to 55,000 cubic feet per second by early next week. The average rate of releases for March was 30,600 cfs. They believe that releases at Gavins Point will be above average for several months, possibly even into November. the Reservoir level at Gavins Point was 1205.4 feet. Releases at Fort Randall with be adjusted as necessary to maintain the desired elevation at Gavins Point.
Four projects on the system, Fort Peck, Garrison, Oahe and Fort Randall, have significant flood control storage and their pool levels increased as they captured much of the runoff. Remus said that to reduce flood risk, they need to reduce pool levels in Oahe and Fort Randall, while Fort Peck and Garrison reservoirs are ready to receive mountain snowmelt.
The mountain snowpack above Fort Peck is 3 percent below average and from Fort Peck to Garrison it is 7 percent below. The mountain snowpack usually peaks in mid-April.
Next Wednesday, April 10, the Missouri River Basin Water Management Division will host a public meeting in Sioux City. it is wet for 4 p.m. at the Sioux City Lewis & Clark Interpretive at 900 Larsen Park Rd.