Unusually dry and warm conditions in March led to below-normal run-off in the Missouri River basin, according to new data from the U.S. Army Corps of Engineers. Steven Predmore, with the National Weather Service’s Missouri River basin prediction office, says flood risks are only average this spring.
That’s a big change from last year when record flooding hit the waterway and lasted all through the summer months. “The National Weather Service continues to project a normal risk of springtime flooding for most areas within the Missouri River basin,” Predmore says. “An exception exists in the Dakotas where we are calling for a slightly-lower-than-normal risk of flooding.”
Jody Farhart, chief of the Missouri River Basin Water Management Division for the Corps of Engineers, says flood storage is right where it should be. “The total volume of water stored in the Missouri River Main Stem Reservoir System is currently 56.9-million acre feet, just 0.1-million acre feet above the base of the annual flood control pool,” Farhat says.
“This means that we have 16.2 of the total 16.3-million acre feet of flood control storage available.” Runoff above Sioux City was 78% of normal through the end of March. Kevin Stom, who’s also with the Corps’ Water Management Division, says their forecasts indicate a below-normal run-off.
“The April 1 run-off forecast above Sioux City is 23.4-million acre feet or 94% of normal,” Stom says. “This is a decrease from the March 1 forecast due to much lower than normal plains snowpack run-off which normally occurs in March and April. In addition, overall mountain snowpack decreased as a percent of normal. Record high March temperatures occurred throughout the basin and precipitation was well below normal.”
Stom says snowpack above Fort Peck Dam was at 97% of normal. Releases from Gavins Point Dam near Yankton will be increased to just under 29,000 cubic feet per second to support navigation from Sioux City downstream. Peak flows during last summer’s flooding maxed out at just over 160,000 cubic feet per second.
By Jerry Oster, WNAX, Yankton