Up to 8 inches of rain has fallen near Decatur, Tennessee over the past couple of days, causing localized flooding and swelling the Chickamauga Lake to a half foot above its normal summertime pool, the Tennessee Valley Authority said today.
James Everett, senior manager of TVA's River Forecast Center in Knoxville, said 4 to 6 inches of rain has fallen over much of northern Hamilton, Meigs and Bradley counties over the past two days and up to 3 more inches of rain is possible in some areas in the next day or two.
"Much of that rain came in a very short duration and that has created a lot of runoff and some localized flooding," Everett said today. "We're spilling water at most of our mainstream dams, but we're still seeing very high lake levels at Chickamauga and Watts Bar."
TVA has cut off most of the flow from its major storage reservoirs at its dams at Norris, Cherokee, Douglas and at other lakes in eastern Tennessee and Western North Carolina to help hold more water back and limit flooding problems downstream.
"As rainfall continues tonight and through tomorrow — and perhaps lingering into Friday and this weekend — we'll remain on high alert," Everett said. "We're not showing any water levels above flood stage at any location on the Tennessee River, although we may get close to flood stage at places downstream like in Savannah."
Rainfall in the eastern half of the Tennessee Valley is 10 inches above normal this year, making 2018 one of the wettest years so far in the 128 years that rainfall records have been kept in the region. So far this year, rainfall above Chattanooga in the Tennessee Valley has totaled 45.5 inches. The highest rainfall in the eastern half of the Tennessee Valley was in 2013 when precipitation for the entire year totaled 62 inches.
Everett urged lake users to be cautious while on the river with increased water flow and he said some lakefront property owners should be prepared for higher lake levels.
"We would expect to be spilling water on the mainstream dams through the rest of the week and perhaps across the weekend," he said. "We hope to be able to make some cuts (in the spilling levels) once the rain quits, but that is still uncertain because we're still expecting perhaps two more inches of rain to fall in the eastern half of the river."
Everett said TVA has talked with organizers of the Little Debbie Ironman Chattanooga scheduled for Sunday and cautioned that TVA may still be spilling water through the Chickamauga Dam, which could affect the swimming portion of the triathlon.
TVA has increased the flow of water through the Chickamauga Lock today to 78,0000 cubic feet per second (or about 550,000 gallons per second) which is significantly above the 46,000 cubic feet per second flowing through the turbines at the hydroelectric station at the Chickamauga Dam.
The flow is still below the 85,000 cubic feet per second that would restrict river navigation on the Tennessee River in Chattanooga.