Corps of Engineers to Increase Coralville Lake Outflows

Rock Island District
Published June 25, 2020
Coralville Tailwater

Coralville Tailwater

The U.S. Army Corps of Engineers, Rock Island District, is preparing to temporarily increase outflows at the Coralville Reservoir. This minor deviation to normal operations, which will occur on or around June 30 depending on precipitation in the area, was implemented due to recent rainfall on already saturated soils that has resulted in high inflows into Coralville Reservoir. 

With an extended period of rainfall forecast for the state of Iowa, the Corps will temporarily increase the release from the reservoir from the current seasonal maximum of 6,000 cubic feet per second (cfs) to 10,000 cfs in order to expedite evacuation of flood waters from the reservoir. Typically, reductions in outflow are made to reduce flood crests downstream of the reservoir. The action levels to trigger reductions will be increased from 14 feet to 19 feet at Lone Tree, Iowa, and increased from 21 feet to 25 feet at Wapello, Iowa.

Updated information about water levels at Coralville Lake is available at This website includes links to the U.S. Army Corps of Engineers and National Weather Service websites which track Coralville Lake elevations, Iowa River flow and projected rainfall amounts.


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Corporate Communications

Release no. 20-056