Eddie, the short answer to you question is at about 60 degrees. But if you want my explanation, keep reading.

Believe me I am not an expert in any of the stuff I am about to write about, but my reason for trying to determine when the Fall Turnover occurs is to be able to be on the water when the Fall Feeding Frenzy occurs. I think that the Feeding Frenzy starts after the temperatures and oxygen levels equalize (become the same/constant from top to close to the bottom) after the Turnover.

Sometime toward the end of September (in most years) the water will start to cool from its Summer time highs and this will cause the shad to move into the creeks and Bass will go after them. I call this the pre-turnover feeding frenzy, although it is not generally as frantic as the Fall Feeding Frenzy.

The pre-turnover feeding frenzy usually occurs in the creeks and longer coves, off the main lake, that are shallower then the depth of the lake’s thermolcline. The water/oxygen in the creeks/coves will be the first to mix but there won’t be a true “Fall Turnover” because there is not a Thermocline it these shallower areas.

Anyhow, I have watched the Corps’ Water Quality Data for the last couple of years. This year, as of September 22nd, the Thermolcline was at about 25 to 30 feet and the water temp. was about 75 degrees. At about 40 to 45 feet, which I think is a good average depth for Nolin, the temps were about 63 to 65 degrees. According to the “experts” that I have read, the Thermlcline will be at a constant depth throughout a lake. In other words, if it is a 30 feet at the dam, it will be around 30 feet everyplace in the lake that is 35 to 40 feet or deeper (there has to be room below the thermocline for the bottom layer to set up).

I think that when the surface water cools to about 70 degress, the water ABOVE the Thermocline will start to mix but not break through the Thermocline. When the upper layer cools to about 60 degrees (in this example) it will break through the Thermocline and cause the whole water column to turn over and mix from top to bottom, When this happens, the oxygen content is all mixed up along with all the muck and debris that comes up from the bottom and lower depths. After the Thermocline breaks up, I think it takes about seven to ten days for the water to stabilize and then the Fall Feeding Frenzy begins. Obviously, all of these timeframes, depths and guesses can vary greatly depending on when the weather changes or doesn’t change also on how fast or slowly it changes,..

The bottom line is that IN MY OPINION in most years the Fall Turnover and the Fall Feeding Frenzy happen sometime in between late September and the middle of November, but generally sometime in October. I love fall fishing, except during and right after the Turnover.

OK, now all of you others can chime in and tell me what you think.

Grumpy