Coralville Lake

History

After widespread flooding in the United States during the early 1930s, Congress passed the Flood Control Act of 1938. The United States Army Corps of Engineers built the 100-foot-high earthen dam primarily as a flood control project for the Mississippi River. Construction started in 1949, was delayed by the Korean War, and was completed in 1958.

The lake has a capacity of 461,200 acre⋅ft (568,900,000 m³) of water, equal to 137.18 billion gallons at its "100 year flood" level of 712-foot (217 m).

Floods

Water first flowed over the 712-foot (217 m) emergency spillway on July 5, 1993 (see Great Flood of 1993), reaching a then-record crest. This flood uncovered what is now the Devonian Fossil Gorge.

The 1993 record was surpassed by the June 2008 Midwest floods, when water again flowed over the 712-foot (217 m) emergency spillway on June 12, 2008, and the reservoir crested at 717 feet (219 m) early in the morning on June 15, 2008.

Lake Macbride is formed by another dam just up from the Coralville reservoir. This dam was overtopped by floodwaters in the flood of 2008, and the lake effectively became part of Coralville Lake.