July 17-18, 1996 Storm Event and the Failure of the Channahon Dam

On July 17-18, 1996 an extreme storm event occurred over a large area of northern Illinois. The heavy rainfall extended from south central Wisconsin across Joliet, Illinois to north central Indiana. The maximum recorded precipitation occurred at Aurora, Illinois. The Aurora Sanitary District station reported 16.91 inches of rain in an 18 hour period. The first section of this paper will describe the storm event in some detail. There are 190 Illinois dams on the national dam inventory located in the area covered by the storm. As of the date of this paper, we know of two complete failures of inventoried low hazard dams, the failure of the feeder canal at the hydroelectric plant at a third dam, and the failure of two previously uninventoried dams. We have observed and received reports of lesser damages at a number of other dams. An unofficial visit at a Corps of Engineers structure on the Illinois Waterway showed evidence of overtopping, but was not reported to the state dam safety office. The second part of this paper will detail the failure of Channa-hon Dam, a low hazard dam originally constructed in the 1840's as part of the Illinois & Michigan Canal. 12 pp., 3 references.