Gavins Point Dam

After record flooding in western Iowa much of last year, runoff into the Missouri River system is expected to be above-normal again this year, but the experts say the runoff will be well-contained in the reservoir system.

Kevin Grode, with the U.S. Army Corps of Engineers in Omaha, says we’ve already had a couple of relatively dry months and that’s been a big help. “Below-normal precipitation in April led to below-average runoff in most of the upper basin,” Grode says. “Precipitation in the upper basin has been well below normal, with some areas of the Dakotas receiving less than half their normal precipitation.”

Grode says the runoff forecast has been dramatically reduced. It originally called for 3.2 million acre-feet of runoff during April but they recorded about 1.3 million acre-feet less. “The 2020 calendar year runoff forecast for the upper Missouri River basin above Sioux City is 32.2 million acre-feet or 125% of average,” Grode says.

Grode says the Corps of Engineers is still expecting above-normal runoff each month this year. “Even with the below-normal precipitation that we’ve seen, we’ve seen above-average runoff in each of the first four months of the year due to the very wet soil conditions,” Grode says. “We are still forecasting slightly above-average runoff for each of the remaining months of 2020.”

He says above-normal river releases all winter allowed the Corps to add more flood storage capacity in the upstream reservoirs.

(By Jerry Oster, WNAX, Yankton)