As heavy Mississippi River flooding is receding along Iowa’s eastern border, the picture is much different on the western border. The experts predict higher-than-average runoff into the Missouri River this summer, but they’re quick to add, the waterway should stay well below flood stage and remain within its banks.
Kevin Stom , an engineer in the U.S. Army Corps of Engineers water control office in Omaha, says they have adjusted their forecasts. “The 2014 calendar year forecast for July 1 is 33-million acre feet, 131% of normal, above Sioux City, and 30.1-million acre feet or 131% of normal above Gavins Point,” Stom says. “Compared to the June forecast, this is an increase of 1.9-million acre feet above Sioux City or 0.8-million acre feet above Gavins Point.”
With all of the heavy rain, Stom says run-off has increased in the past couple of months. “June runoff was 8.3-million acre feet above Sioux City, or 153% of normal, and 1.2-million acre feet greater than forecast,” Stom says. “However, about 0.8-million acre feet of this additional runoff occurred in the Gavins Point to Sioux City reach as a result of the record flooding on the Big Sioux River.”
Corps engineer Alex Flanagan says there’s still plenty of water storage space in the upstream reservoirs. “We have 60.6-million acre feet stored and this is 4.5-million acre feet above the top of the carryover and multiple use zone,” Flanagan says. “At this current storage level, 11.8-million acre feet of the 16.3-million acre feet total flood control storage is available to benefit flood risk reduction.”
Forecasters say precipitation across the Missouri River basin is expected to be above-normal for the next three months.
By Jerry Oster, WNAX, Yankton