Going with the Slow Flow

As summer gives way to a dry and hot early fall, lake levels continue to drop as TVA works to meet its system minimum flows for navigation, power production and water quality.

OCTOBER 2, 2017—From a meteorological perspective, late August and early September were scary, with the whirling specters of Hurricane Harvey and Hurricane Irma threatening the southeastern seaboard of the U.S. Indeed, when they came ashore, the damage they caused was massive.

The land-locked Tennessee Valley was never in danger of the kind of intensity that much of Texas and Louisiana saw, of course, but was certainly susceptible to follow-on tropical rains, which had the River Forecasting Center hedging its bets and dropping water levels. “We lowered much of the main river ahead of those storms so that we had ourselves in a good position if we were going to get the kind of torrential rainfall that’s been associated with other hurricanes,” explains James Everett, River Forecast Center Operations support manager. “As it turned out, we got fortunate and flooding along the Tennessee River was a non-issue.”

In the weeks since, the weather has been dry, with rainfall at only 15-20 percent of normal levels—and the outlook for October is looking dry, too.

fishermen in the fall

Now, TVA is releasing water from the tributary lakes into the main stem river system slowly and steadily to meet not only winter flood guide targets, but to ensure a host of other benefits are provided, including water quality and electric generation. “Another thing we’re working hard on right now is coordinating water levels to maintain minimum depths for navigation,” Everett says. “We have to consider the Tennessee River, but also conditions on the Ohio and Mississippi, which do have a big impact on our coal plants and barge movements in the Tennessee and Cumberland valleys. We need to make sure barges can get through the entire inland waterway system with minimal problems.”

Water temperature is an issue now—whereas a cool snap in August was favorable for operations, now flows must be sufficient to keep river temps under control at nuclear and fossil plants. So, too, are dissolved oxygen levels and water quality under careful observation. “We are always maintaining our minimum flows to support aquatic life,” Everett notes.

Slow and steady is the name of the game, according to Everett: “We’re running a marathon now, not a sprint. We want to spread the drawdown out.”

Recreation is still top of mind for the River Forecast Center. ‘We’re still doing recreation releases; we’ll continue them for the Ocoee into October,” he says. “We just accommodated a large Iron Man event in Chattanooga, and we receive flow requests for bass tournaments and we try to work with them if the weather is favorable—we take them on a case-by-case basis.”

The moral of this story? Appreciate the high water quality and safety TVA’s trusted river management system affords you. And recreation season is still on: Get out there on the water and play amidst the autumn color!

The River Forecast Center

TVA’s River Forecast Center—located in Knoxville, Tenn.—is staffed around the clock, 365 days a year, monitoring the river to control flooding, as well as water quality data, availability and demand—all with the goal of routing water through the system to provide the most public value given changing weather conditions and water demands. Read more about the River Forecast Center.