Several factors affect the water temp on that river. Primarily water temp in the lake is the major contributor. But once summer sun hits the large shallow flats that ae all along the river, that flat shallow water warms a lot during the day. When the pulses get in to that flat water and push it in the main flow of the river there are some places when that occurs where one leg will be standing in warm water flow (from the flats) and the other in cold water flow(from the dam release). Further down the river the greater this temp affect , and when river temp pops up from that pulse carrying warm water the fish are effected , both feeding wise and fighting wise. Spring inflow and more two generator discharge usually offset the warm flat inflow, but this year has not seen the affect of this factors as much.
Good news is that TVA has added in last year or so an additional 12 miles or so of ventilated tubing that carries liquid oxygen into the bottom of cherokee lake, which has the affect of both re-areating the lake (and discharges even more) plus some cooling affects. The larger holdover fish that are in the river this year undoubtedly benefited a lot from that improvement. When you see all the improvements in the tailwaters cold water quality, it makes you sort of scratch your head about why TVA would consider walking away from supporting the trout sticking programs when it has spent millions to improve the oxygen and temp issues in the last three decades?
Personally l think the intense daily fishing pressure in some areas of the river have affected the condition of the fish. Many of the larger fish are caught several times a week and that stress is taking perhaps more toll on the fish than the water temps. Careful handling and releases are important to get the fish revived in many instances. This is particularly true in the rivers lower reaches i think as several guides seem to have spent the spring there.