Coralville Lake averts more than $105 million in flood damages

Published June 18, 2013

ROCK ISLAND, Ill.  – (June 18) During the recent heavy rainfall events in the Iowa River basin, Coralville Lake outflows were regulated to help lower river levels and minimize flooding to communities on the Iowa and Mississippi rivers. The reduced river levels resulting from the operation of Coralville Lake prevented more than $105 million in additional flood damages to downstream areas.

Inflows to Coralville Lake peaked at 40,000 cubic feet per second (cfs) June 1, while the maximum outflow was held at 18,400 cfs. Storing flood waters and reducing outflows lowered the Iowa River by approximately 6.2 feet in Iowa City, Iowa, and 3.8 feet in Lone Tree, Iowa; and nearly ½ foot at Quincy, Ill., on the Mississippi River.

Coralville Lake peaked at 708.44’ June 5, using 80 percent of its available flood storage. The lake is currently at 701’ using 43 percent of its available flood storage.

Coralville Lake was built and is maintained by the U.S. Army Corps of Engineers, Rock Island District, and is operated as a multi-purpose reservoir. The primary purpose authorized by Congress is flood risk reduction for areas below the reservoir. Other purposes include recreation and conservation. Coralville also maintains a conservation summer pool to augment low flows during drought and an additional fall pool rise to accommodate migrating bird species.

For more information about Coralville Reservoir visit

Release no. FY13-06-27