Subsurface food is available year round and since the tailwaters have generally consistent temps they are active year round.
Unless you are intent on catching these rising fish on a dry fly or surface patten, when the fish are rising nymph patterns are often still more productive.
Small stonefly nymphs, pheasant tails from 14-18, and scud/sowbug patterns will often be as or more productive. Sometimes you just have to figure out where the trout are in the water column and get the nymph at or just above that level. Sometimes the fish will be just 6 inches from the surface or sitting tight to the bottom.
The fish are often seeing a lot less presure this time of year and some real hogs can be found out feeding in bright sun.
You must have a drag free drift and a fly they are willing to eat.