All that investment there will be a good thing!! The locals will make some money, and the Nashville boys will go bankrupt, and that ought to keep them quiet for a while...

Seriously, in the first 10 miles or so of river the only naturally occuring invertibrates are midges. That may change with the new schedule being a bit more consistent, especially further downstream towards Old Dam Ford. I have never seen anything coming off that I could characterise as a "mayfly".
You will see some terrestial activity, especially hoppers, inch worms, and ants as well as the occasional worm and bait fish. But other than a hopper pattern, and cracklebacks, it's midge size flys that consistently pull in the fish.
Ralph