The U.S. Army Corps of Engineers is boosting releases from Gavins Point Dam and other mainstream Missouri River dams to prepare its reservoirs for the upcoming runoff season.
Jody Farhat, chief of the Corps’ Missouri River Water Management Division, says Gavins Point releases will be stepped up this month from 17,000 to 24,000 cubic feet per second. That will help to move water out of flood storage.
Farhat says releases from Gavins Point and other dams may be further adjusted during January and February, depending on observed runoff. Farhat says the river reservoirs are being lowered ahead of the spring snow melt.
“Runoff in 2015 was very near average although the timing and distribution was not,” Farhat says. “Releases from the main stem reservoirs are being adjusted to evacuate the remainder of the water stored in the annual flood control zones and prepare the reservoir system for the 2016 runoff season.”
During the winter, the corps will closely monitor ice conditions below Garrison, Oahe and Gavins Point dams, and make reservoir regulation adjustments to lessen the impact of river ice formation.
Kevin Stamm, an engineer in the corps’ water management division, says current conditions would lead to lower-than-normal runoff. Stamm says, “The 2016 calendar year runoff forecast for the Missouri Basin above Sioux City, Iowa, is 23.8-million acre feet, which is 94% of average.”
Mike Swenson, who’s also with the water management division, says the reservoirs have all of their flood capacity ready.
“On March 1st, which is typically near the start of the runoff season, the basic simulation shows system storage right at 56.1-million acre feet,” Swenson says. “This means that the reservoir system would start the runoff season at the base of the annual flood control zone and that all 16.3-million acre feet of flood control capacity will be available.”
Cold temperatures typically form river ice on the Missouri River and its tributaries above Sioux City. However, corps officials say warmer-than-normal temperatures in December inhibited ice development and runoff was 155% of average.
Reporting by Jerry Oster, WNAX, Yankton and Mike Peterson, KMA, Shenandoah