Rain is welcome, but much more is needed

Executive Director Doug Murphy said that between 10 to 15 more inches of precipitation over the next three months is needed to make "a significant impact" to the level of the lake.

"If we are going to get it, it has to be now. The next few months are going to be real critical," Murphy said.

It would take an average of five inches a month to get the level up to the lake's winter pool as stated in Tennessee Valley Authority's operating guidelines for the reservoir, which would be near 864 feet.

Measurements taken at Normandy Reservoir Friday placed the elevation at 852.12 feet. As of Tuesday morning, that level had risen to 852.98 feet.

However, Murphy cautioned that the manual gauges which TVA uses to measure the level of water at the dam are still out, and that the numbers posted on TVA's website are modeled from their estimates of how much is in the lake.

"They only measure it manually three times a week," Murphy said. "You have to enter in evaporation rates also."

Murphy said that the wettest months for the region are January through April, but that only 50 to 75 percent of the rain that falls turns into runoff that would end up in the lake. The region gets an average of 52 inches of rain per year, or an inch per week.

However, the National Weather Service is predicting that after March, the area will see above normal temperatures and below normal rainfall.

The bureaucratic process of lowering the flow from the reservoir is still underway as well, Murphy said.

If all the involved parties, such as TVA and the Tennessee Department of Environment and Conservation (TDEC), agree to a discharge reduction at Normandy, or to change the lakes winter operating guidelines, it will have to be due to a change at gauge 221.4, which is the location of Shelbyville's water intake.

The city's wastewater plant currently requires a flow of 120 cubic feet per second (cfs), but if the plant is allowed to operate at a flow of 100 cfs, the amount of water released from the dam can be slowed, Murphy said.

The rainfall the area has received has also increased the runoff which feeds tributaries -- and their added inflow into the Duck River gives TVA more of an ability to reduce the discharge.

Currently, the flow from the dam is running between 44 and 46 cfs. The extra flow into the river from other tributaries will give TVA a reason to hold back more water as well.

"It's looking better, but I'm really waiting for that graph to turn and skyrocket," Murphy said. "That's what we want to see. Our best chance is in the next three months."

In the meantime, area residents should keep an eye on the skies today due to the possibility of violent weather. According to the National Weather Service, a strong low pressure system will move into the area today, bringing with it a line of storms that could contain damaging winds, hail, and a few tornadoes.

The greatest potential for bad weather is early Wednesday morning, when it is expected that a strong line of storms will move through the area.