Ken, FWIW, I was thinking about it as I read through this post, but I don't think you'll find a hemlock along any reach of BS. I'm glad to hear that others have seen the spawning of brookies in January at BS, I believe these spawning brookies from the original strain of natives.
I've been to BS many times and have seen some pretty good hatch activity there and many fish rising to those hatches. The problem is in the catching. Those brookies are some difficult fish to catch, they can be tougher to catch than some of the browns I've fished over in many PA. streams. That's one of the reasons why the Loch Leven Trout were put in many Cumberland Valley Streams.