Looks like some guy knows a thing or two about that river.- http://www.totalflyfishing.com/index..._in_a_Lifetime
Then there's this
Other than that its hard to find man. You'd probably be covering your bases with some yellow stimulators in sizes 12 and 14, and some princes or zug bugs in the same. On the other hand, if the stones are little yellow sallies, you'll want 16's and maybe 18's and smaller nymphs as well. There's also a possibility of there being little black stones around, but they're least common nationwide.
There's no chance of needing any of the gigantic (size 4 or 6) salmonfly patterns, as those hatches all happen west of Yellowstone.