TVA spilling water from dams due to heavy rainfall

Chattanooga is over 13 inches above normal in rainfall to date for 2020 with more falling on Wednesday, and with the heavy rain, comes runoff and the need to control the water flow.

The above-normal rainfall extends beyond Chattanooga to the entire Tennessee River Valley, where over 30 inches of rain has fallen. This number is not typically reached until July.

Although we’ve had serious flooding this year, there is an upside to all of this rain: increased generation of hydroelectric power like at the Chickamauga Dam.

“It’s very flexible. The fuel is free. It’s from Mother Nature, and so we’re utilizing this extra flow to run water through as much hydroelectric turbines as we can at the dams,” James Everett, Manager of TVA’s River Forecast Center in Knoxville told Channel 3.

About a half-million gallons per second were flowing through the generators and spillway gates at Chickamauga and Nickajack Dams on Wednesday. Watts Bar reported 400,000 gallons per second.

“Looking back at the last 7 days, we’re about 300% of normal for hydro generation,” said Everett.

That’s 3 times the typical amount, and the dams are about 35 percent above normal for 2020 so far.

“That hydroelectric generation is very, very cost-effective and can offset some of those more expensive forms of generation, and then those savings can be transferred to the ratepayer,” Everett explained.

2020 is outpacing 2019, which set a record for rainfall and runoff.

Runoff is the portion of rain that enters back into the reservoir system through streams and groundwater. It plays a big part in both power generation and flooding.

“We’re already about 22 inches of runoff for the year, which is what we would normally see during an entire calendar year, and we’re just now 4 months through the year,” stated Everett.

Managing the river is a balancing act of demands, needs, and Mother Nature, so operating plans are constantly being adjusted.

“We’re using the system of dams in an integrated manor to store water, reduce flood levels downstream, and provide a tremendous amount of flood protection in areas like Chattanooga,” Everett said of the process.

The River Forecast Center is monitoring conditions 24 hours a day to try to provide the best combination of flood control, power generation, navigational and recreational abilities, and water supply and quality along the Tennessee River.