Coralville Lake is an artificial Johnson County, Iowa, reservoir created by the Coralville Dam on the Iowa River. The main purpose of the U.S. Army Corps of Engineers-built dam, which was built between 1949 and 1958, is flood control. The 100-foot-high dam impounds a large area, forming Coralville Lake with a surface area of 5,280 acres under normal conditions, which can expand to 24,800 acres during flood events.
The lake has significant storage capacity for flood management, holding up to 421,000 acre-feet of water in the flood storage pool. Notably, the lake first overflowed its emergency spillway in the Great Flood of 1993 and again during the 2008 Midwest floods, temporarily merging it with Lake Macbride upstream.
Coralville Lake is surrounded by a wealth of recreational opportunities, including boating facilities, fishing spots, hiking and bicycling routes, and camping areas. The area features 11 recreation spots, 4 swimming beaches, 3 marinas, 18 boat ramps, 3 campgrounds with 620 campsites, 7 large picnic shelters, 2 disc golf courses, and 7 trails totaling 29 miles.