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The Tennessee Valley Authority released data Monday that was collected during, and after, Tropical Storm Helene that provides insight into the magnitude of the storm that swept across the Appalachian region beginning Friday, Sept. 27.  

Significant and catastrophic flood damage to communities occurred throughout northeast Tennessee and western North Carolina. These were areas where TVA flood control operations could not mitigate impact. Our hearts go out to these communities. When that floodwater began flowing into the Tennessee River watershed, TVA’s network of dams, and employees, were already at work to protect people downstream. 

Data shows that TVA’s flood mitigation strategies prevented approximately $406 million of potential damages; dams in the TVA system stored 404 billion gallons of water; enough to gill 612,000 Olympic-sized swimming pools; and two months of normal rainfall fell in three days on the Tennessee River watershed.

“Greene County was aided immeasurably by engineer representatives from TVA from the very early stages of the storm and flooding affecting Greene County,” said Greene County Mayor Kevin Morrison. “TVA’s timely, accurate, and wise forecasting and professional advice to our leadership team on the conditions of the Nolichucky River and the Nolichucky Dam saved lives. We are eternally grateful to the TVA team for standing side by side with us throughout this disaster, recovery and rebuild.”  

Providing flood control of the Tennessee River is a core mission of TVA and has been since its inception more than 91 years ago. Evaluating rainfall and stream flow data from across the Valley provides engineers in TVA’s state-of-the-art River Forecast Center the information to make operational decisions to minimize flood impacts along the river system 24 hours a day, seven days a week, 365 days a year. 

Using computer modeling, TVA tracks what might have happened without dams and flood mitigation as a way of helping determine how well its system is operating. That data collectively informs “flood damage averted” calculations.

Data from this event shows that flood mitigation strategies enacted by TVA prevented approximately $406 million of potential damages in Lenoir City, Chattanooga, Kingsport, Elizabethton, Clinton, and South Pittsburg. Since TVA’s inception in 1933, more than $10 billion in potential flood damage has been averted.

Potential flood damage averted by TVA to Elizabethton was estimated at $5,100,000; to Chattanooga, $166,000,000; Clinton, $2,600,000; Lenoir City, $136,000,000; Kingsport, $75,200,000; and South Pittsburg, $1,200,000

“This was some of the highest flood levels we’ve seen in the Tennessee Valley in its entire history,” said James Everett, TVA’s general manager of river management. “We saw a record amount of flooding and we saw tremendous amounts of rainfall that caused that flooding. TVA’s dams and the people who manage these dams stepped up to that challenge and managed this record setting event.” 

“No one could have imagined the destruction Hurricane Helene would unleash on our community and our utilities. One of the first calls I received was from TVA to understand how dire our situation was. TVA provided valuable support, manpower, and equipment to aid in our restoration of power and early damage assessment at our wastewater treatment plant,” said Lee Brown, Erwin Utilities President & CEO. “TVA enabled us to move quickly and efficiently in our work to recover from Helene. Our partnership with TVA and other local power companies is the perfect example of the benefits provided by Public Power.”

Records show that the Watauga River at Elizabethton reached 5 feet above flood stage and is the highest flood level in Elizabethton since 1940.

TVA’s Watauga Dam on the Watauga River in Carter County, east of Elizabethton, reached an elevation of 1,970.29 feet, which broke the previous record by about three feet. 

The Doe River at Elizabethton reached 10.78 feet – nearly 3 feet above Flood Stage and just inches below the flood of record in 1998. 

TVA is continuing work to support communities and local power companies in recovery efforts.