Lake Delton is a man-made freshwater lake in Sauk County in central Wisconsin. For much of 2008, it was a mostly empty lake basin after a portion of a county highway that forms part of the dike wall eroded on June 9, 2008, under the pressure of floods in the area. The resulting washout caused the lake to empty, leaving behind only rainwater pools and the flow from Dell Creek. By March 2009, major repairs to correct the problem were completed, and the lake was allowed to refill. Minor repairs were expected to continue after that time, but the lake is now completely refilled and has been usable since Memorial Day weekend of 2009.
The lake was formed in 1927 to attract tourists to the area and became a popular attraction in the Wisconsin Dells tourist area following the economic recovery after the Great Depression. Resorts and tourist attractions line its banks. The lake is the site of Tommy Bartlett's Thrill Show, which features acrobatic water skiing.