Taum Sauk Water Storage Dam Failure

Event Year: 2005 Reliability: Confirmed
Country: United States
Industry Type: Power and Utilities

On the morning of December 14, 2005, the dike at the Taum Sauk Upper Resevoir failed.  The water in the Upper Resevoir was released into the East Fork of the Black River, located upstream of the lower Taum Sauk dam.  The 1.3 billion gallons of water flowed from the Black River, through Johnson’s Shut-Ins National Park into the Lower Resevoir, and then continued to flow down the Black River to the the town of Lesterville, Missouri. The water released destroyed the home of the Johnson’s Shut-Ins State Park superintendant, flooded motorists, and significantly damaged the park, campground, and adjacent properties.  There were no fatalities, however, the Park Superintendant and his family were injured when they were swept away by the water.  According to The Federal Energy Regulatory Commission (FERC), The primary cause of the Taum Sauk breach was overtopping of the upper resevoir due to improperly maintained and installed water level monitors.  The monitors became loose and indicated the resevoir levels lower than actual levels.  It was also found that emergency back up sensors proved ineffective because they “were set at an elevation above the lowest points along the parapet wall; thus, they failed their protection role because this enabled overtopping to occur before the probes could trigger a shutdown.”  In addition, Ameren typically operated with high water levels of one foot below the top of the parapet wall, which did not take into account any possible mistakes in operation.


The damage to the Johnson’s Shut-Ins National Park was extensive.  The Taum Sauk dam failure has been called the “Worst Man-Made Disaster in the history of Missouri”. FERC fined Ameren $15 million pursuant to a settlement for the breach at Taum Sauk.  The State of Missouri sued Ameren for Actual and Punitive Damages alleging Ameren reckless in its operation.  In November 2007, the state reached a $180 million settlement with Ameren.  The settlement reached compensates the people of Reynolds County and the state of Missouri for the loss of natural resources and recreation.

Action Description: The upper reservoir dam is being replaced with a roller compacted concrete dam.