10th Anniversary of the Taum Sauk Dam Failure

The original Taum Sauk Upper Reservoir Dam was located in Reynolds County in southeast Missouri (Figure 1). The dam was part of a pumped storage project owned by Ameren Missouri. Construction started in 1960 and operation began in December 1963. The 55 acre upper reservoir was impounded by a 6,562 feet long kidney shaped dike. The embankment was constructed of dumped sand and rock fill, with a concrete lined upstream face. The downstream face was at the natural angle of repose of the
rockfill/sand shell at a 1.3:1 slope. The dam had a hydraulic height of approximately 90 feet which included a 10 feet tall reinforced concrete parapet wall. There was no spillway or overflow structure. On December 14, 2005 at 5:15 AM, the northwest side of the upper reservoir was overtopped when water from the lower reservoir continued to be pumped after the upper reservoir was full. A 680 feet wide trapezoidal shaped section of the upper reservoir embankment failed releasing approximately 4,600 acre-feet of water down the west slope of Proffit Mountain, into the East Fork of the Black River. The flood moved downstream through Johnson’s Shut-Ins State Park back into the lower reservoir on the East Fork Black River. A Missouri state highway was inundated by the flood, pushing two vehicles off the road. The home of the park superintendent was ripped apart, leaving only the concrete foundation. The park superintendent and his family, who were home when the flood wave hit their house, miraculously survived, as did the drivers of the two vehicles swept off of the state highway. Flood depths were greater than 50 feet as the breach wave flowed down the side of Proffit Mountain and as much as 40 feet along the East Fork of the Black River. A large amount of sediment and debris was deposited in the park and further downstream in the lower reservoir. The state park campground, empty at the time of the failure, was inundated by up to 40 feet of water. The dam was later rebuilt using roller compacted concrete.