I will defer to the people who fish those rivers for their favorite flies. I take that back. You should always have a selection of various buggers and Clousers with you wherever you go.
If you want to do a little leg work on your own do a Google search for "hatch chart (name of river)." These hatch charts usually tell of the bugs that are seasonally on the water and some examples of the flies.
For example, "hatch chart Current River" leads to this
website first in a Google search.
Good luck on your search.