I haven't fished that part of the country, but generaly speaking, I have done a lot of Trout fishing. Alway's with spinning gear, mostly use CELTA's, a small blade spinner, with good returns. As for fly fishing I am very ammaturist at it, it is an art on it's own. People I know that fly fish generally don't have the catch rate of spinning. Being a dam shouldn't be a problem, are you fishing from the bank or a canoe? Have caught trout in dams of varying size again with spinners. Another good lure for dams is the Tassie Devil. Alway's allow your spinners to sink before you start to retrieve. With your Fly rig, see what type (if any) of insects are hanging around the banks and water surface, and try to match your fly to that. Hope this help's, good luck. Trout are a great sport fish, and don't give them ay slack in your line or you will lose them.
Cheers
Rob T/Red C