ROCK ISLAND, Ill. (May 16) – Following the heavy rains in April the Corps of Engineers began storing flood waters at its three reservoirs (Coralville, Red Rock and Saylorville) to reduce the amount of flooding downstream.
Coralville Lake, just north of Iowa City, Iowa, on the Iowa River, peaked April 24 at elevation 697.5’ using 32 percent of its available flood storage. The operation of Coralville Lake prevented more than $41 million in damages to areas downstream. In particular, the reduction of outflows at Coralville reduced the Iowa River level by six feet in Iowa City.
Saylorville Lake, located 11 miles north of Des Moines, Iowa, on the Des Moines River peaked April 20 at 836.99’ using one percent of its available flood storage. The operation of Saylorville Lake prevented $94,800 in damages to the Des Moines area.
Lake Red Rock, located 60 miles south of Des Moines, Iowa, on the Des Moines River peaked April 23 at elevation 757.2’ using 25 percent of its available flood storage. The operation of Lake Red Rock prevented more than $12 million in damages to areas downstream. In particular, the reduction of outflows at Lake Red Rock reduced the Des Moines River level by 11.3 feet in Tracy, Iowa and 5.3 feet at both Ottumwa and Keosauqua.
In addition, the operation of Lake Red Rock and Coralville Lake reduced river stages on the Mississippi River by nearly two feet at both Quincy, Ill., and Hannibal, Mo.
The three reservoirs (Saylorville, Red Rock and Coralville) built and maintained by the U.S. Army Corps of Engineers, Rock Island District, are operated as multi-purpose reservoirs. The primary purpose authorized by Congress is flood prevention for areas below the reservoirs. Other purposes include recreation and conservation. Corps reservoirs also maintain a conservation summer pool to augment low flows during drought and an additional fall pool rise to accommodate migrating bird species.
The Rock Island District, with its cost-share partners, has built nearly 100 flood risk management projects, in addition to more than 550 combined miles of levees and floodwalls along its reaches of the Mississippi and Illinois rivers and their tributaries.