The Tennessee Valley Authority (TVA) is taking steps to account for the massive rainfall Florence could bring. The TVA manages lakes and reservoirs in east Tennessee and parts of Virginia, Georgia, and North Carolina. These watersheds in turn have tributaries which feed into the Tennessee River.
James Everett, Manager of the River Forecasting Center for TVA, says "it's like a tree, all of those branches feed back to it." "People think of these events as local, but they are actually regional events," Everett says.
The entire Tennessee watershed is 42,000 square miles with 49 dams. If a segment of the dams reach levels too high, water has to be released and it impacts rivers and creeks downstream. The TVA is hoping their current actions will help curb what could be a serious matter if Florence dumps the heavy rainfall expected.
The TVA is currently releasing water to bring lake levels down to account for the potential rainfall. As it stands, levels are already higher than normal since it's the summer season. The lakes are kept at higher levels for the summer and then TVA brings levels down in the winter and spring to account for rainfall during the January-March months.
However, Everett says lakes are already at an 8" surplus and it's not even in-season. If Florence were to bring the 8-12 inches of rainfall expected, it could pose big problems. "Even just two inches could cause a high runoff that will affect rivers and creeks," Everett says. "The problem right now is we don't know how much rainfall we will see or where, so we are monitoring things closely and will revise our strategy as needed."
It's not just portions of east Tennessee which could see impacts. Areas such as Knoxville, Chattanooga, Paris, and Johnsonville could see impacts even if the weather isn't severe there. The mountainous regions in the Tennessee and Carolinas are expected to see heavy rainfall and all the runoff goes downstream, feeding the Tennessee River.
Everett says the TVA will strongly urge Tennesseans who use waterways to be extremely cautious. Everett says there is already a high flow taking place in Knox County and more could come, so residents should be aware.