Further details were released regarding the massive water flow that resulted from the rainfall associated with Hurricane Helene.
Will Reid, deputy commissioner and chief engineer of TDOT, said Sunday. The peak daily water flow of Niagra Falls is around 700,000 gallons per second. The flow rate over the Nolichuckey Dam was estimated at 1.3 million gallons per second. The Nolichuckey Dam is around 482′ wide. Niagra Falls is 3,640′ wide.
TVA estimates that the river was rising at two feet per hour with over a million gallons pouring over the dam every second.
The Nolichucky Dam peak water elevation hit 1266.0’, which is 9.5 feet over the record elevation of 1256.5’ set on November 6, 1977. The 1.3 million gallons per second flow rate at 11 p.m. on September 27, more than doubles the flow rate of 613,000 gallons per second from the previous regulated release in 1977.
On September 27 at about 11:30 p.m. ET, out of an abundance of caution, TVA issued a Condition Red alert, which meant that a breach was imminent. The alert was issued due to a lack of visibility at the dam and high water levels at the dam that were rising at that time about 2 feet per hour.
Once water levels began to reduce and daylight came, the warning was lifted.