I spent the last 2 weeks on the MO between Holter Dam and Prewitt Creek close to Craig MT. The Nymphing was outstanding, hooking up 30 to 40 big fish a day, 17 to 23 inch bows and browns. scuds, caddis pupa, sj worms white/pink seemed to produce the best. Dry fly fishing was slow but we found a few fish rising to caddis here and there.
good luck! Brooks Jessen MT guide# 9431 Montana Fly Fishing, Missoula Montana, Montana Fly Fishing for Trout. Classic Journey Outfitters.