The Taum Sauk Pumped Storage Powerplant in Reynold County, Missouri (USA) was constructed between 1960 and 1963 to store water for generation during peak daytime power demands. The plant consists of a lower reservoir, which is sited along the East Fork of the Black River, and an upper reservoir, which is formed by a kidney-shaped rock-fill dike approximately 50 to 87 ft (15.2 to 26.5 m) high, capped by a 10-ft (3.05 m) concrete parapet wall set on crest that is 12 ft (3.66 m) wide. The Upper Reservoir held 4,600 acre-ft (5.67 billion liters) when filled. A variety of design/construction flaws, an instrumentation programming error, and human errors contributed to a catastrophic failure of the Upper Reservoir on December 14, 2005. Malfunctioning and improperly programmed and/or placed sensors failed to indicate that the reservoir was full and did not shut down the facility's remaining pump unit until water had been overflowing for 6 to 7 minutes. This overflow undermined the parapet wall and scoured the underlying embankment, leading to a complete failure within that time frame. The peak discharge from this outbreak flood was estimated to be 289,000 cfs (8,184 m3/s), obliterating most of Johnson Shut-ins State Park, where, miraculously, only five people were injured. The flood pulse was significantly mollified by capture within Lower Taum Sauk Reservoir, and the maximum discharge over the Lower Taum Sauk Dam was limited to just 1,600 cfs (45.3 m3/s), precluding any significant downstream damage.
