Newly released documents show Wolf Creek Dam passed two major inspections in the 1990's before showing signs of strain.
Repairs are now underway on the dam which holds back Lake Cumberland.
The U.S. Army Corps of Engineers says it started spotting problems in 2004. Several wet areas formed on the earthen portion of the dam. They also found leaking inside the concrete part and cracks in the road that runs on top of the dam.
Lake Cumberland has since been lowered so repairs can be made.