Re: Book on Hatches.
There is a small laminated booklet- A Smoky Mountains &Southern Appalachains Fly Hatch Schedule by Ken Snelling. Cost less than $10. I am sure LRO has copies. Probably the best I've found. Lists flies by month, time of day emerge, suggested patterns. Really you don't need anything else. I've gotten all three books of Fishing the Smokies (I"M A BOOK JUNKIE) and this is the best for general use. Keep it on my tying table when putting fly boxes together by seasons.
Remember flies hatch according to altitude, weather, etc. NOT according to some book. Guys fishing from Townsend to Metcalf may see Sulfurs and Yellow Sallies weeks before I would high above Elkmont.
I'll echo the others and suggest Fishing Report or posting before leaving. Another forum-Southeasternflyfishingforum.com- has large number of tailwater folks from Tenn and NC posting who would be glad help if you post or shoot them an email.