While parts of central Iowa saw severe flash flooding and damage to hundreds of homes after recent rains, Missouri River levels are expected to stay high throughout summer and into fall. Hydrologist Kevin Stamm, with the U-S Army Corps of Engineers, says they’re revising up all estimates for the Missouri due to unusually high mountain snowpack run-off.  Stamm says, “The 2018 calendar year run-off forecast for the Upper Missouri basin above Sioux City, Iowa, is 39.8 million acre feet, which is 150% of average.”

June run-off into the system above Sioux City was about 300-percent of normal. Joel Knofczynski, a senior hydraulic engineer in the Corps’ Omaha office, says there’s still room in the reservoirs upriver to hold back very large quantities of water.”Reservoir system storage is currently 68.4 million acre feet, or 12.3 million acre feet into the 16.3 million acre feet of available flood storage,” Knofczynski says. “Approximately 25% of the flood storage is still available to capture run-off.”

Knofczynski says releases from Gavins Point Dam near Yankton are already strong and they’ll increase substantially over the next few days. “Currently, Gavins Point releases are 42,000 cubic feet per second and will be increased to 60,000 cubic feet per second and possibly higher as downstream tributary flows recede,” he says.

The Corps expects to maintain the high flows into the fall months to get the upstream reservoirs down to ideal winter levels.

(Radio Iowa)