It was Craig Matthews, at Blue Ribbon Flies that told me that the left side below $3 Bridge was private. I figure he should know. I didn't see any Posted signs, but why take chances?
We drove by Reynold's Pass several times (almost daily), but we never tried to fish right there. The water was just a tad deep for wading, I don't think you could have gotten out that far when we were there. It's highly variable, though, you just don't know from week to week what the wading conditions will be.
The fish are definitely bigger than what we are used to. Anything under 14" is small, and 16" to 18" is only average. Whitefish are fun to catch too, although I wouldn't target them. The Madison between Hebgan Lake and Quake lake is another good stretch. Reasonably good access and fairly wade-able.
We used a lot of local flies, as well as a few standards. In Sept, hoppers should be good. I used a lot of double nymph rigs, like a size 12 hare's ear on top and a size 18 red serendipity on the bottom. Lots of weight to get it down, because that water is really moving!
If I weren't going to Alaska with Al, this year, I'd be planning a return trip to MT.