John, I'd love to hear what you find if you go this weekend.
This is a great thread. I've been intrigued with it pretty much since you started it. And I've even referred a number of friends to it. Finally, I was thinking that maybe this would be the year that I'd get off my couch and make the drive over the mountain, and I may have even talked a couple of fishing buddies into going with me sometime in the next couple of weeks.
As for the comments on Anakeesta, it's a bit late to be responding, but I was fortunate to be a tag-along at a meeting with some folks from the Carter administration back in the winter of 1980 when they were just getting serious about construction on the Cherohala Pkwy on the Tennessee side.
Randy Brown, the president of the Chattanooga TU chapter at the time, and Don Byerley, a trout fisherman and geology professor at UTK had set the meeting up over concerns about sulfuric acid leeching into McNabb Creek and a couple of neighboring tributaries to North River in Tennessee as a result of blasting through Anakeesta rock formations near Rattlesnake Rock.
The meeting resulted in a good bit of remediation (allowing piles of lime to leech into the creek to balance out the pH) which has finally brought McNabb creek back w/in a range that brook trout can tolerate at least if the recent droughts would hold off.
But as for Jim's supposition that this might have happened naturally, I'm not so sure.
The mechanism for the acid leeching goes something like this. The Anakeesta rock contains iron sulfate, naturally, but when you break open those deposits and expose them to air and water, you end up with sulfuric acid seeping into the runoff which, in turn, lowers the pH of the affected streams. Forgive my sloppy science, and please no one tell my dad who is a retired chemist, but that's the gist of it.
Anyway, at that meeting back in '80 someone mentioned that the precedent for this problem was set by construction of the Newfound Gap road in the Smokies. They also said that over time the exposed iron sulfate gradually dissipates, and the pH gradually heads back to whatever was normal.
I had no idea just how gradual that might be, though. Fast-forward to early last Spring. Again, I was tagging along with one of the teams of volunteers made up, primarily, of E. Tennessee TU members on their long-running acid deposition/stream sampling project in the Smokies.
I can't remember the name of the first creek that we checked, but it's the first large tributary to the Ocanaluftee River that you cross after heading down 441 on the NC side of Newfound Gap. The first sample was taken at the pull-off, there, upstream from the highway, and was normal.
However, the next sample was taken immediately across the road and downstream from where the creek flows under the highway. At this point, the roadbed is built up from fill that resulted from blasting through the Anakeesta rock formations.
I was startled to see that the stream bed appeared to have been scoured clean. Not clean of dirt, but clean of anything alive, like moss or algae or any plant or bug life. It appeared that someone had dumped in a bottle of bleach somewhere upstream. I've never seen anything like it. It looked like a ribbon of brand-new, shiny rip-rap for the several hundred feet from the road cut to where the stream fell out of sight.
So will nature heal itself? Sure, given time. Just look at the Smokies, themselves. But the Newfound Gap road cut was made about 70 years ago. And you can be sure that if the Cherohala road crews hit Anakeesta near Rattlesnake Rock on the TN/NC state line that they also hit it on the NC side.
Anyway, enough of the history lesson, we never seem to learn from those, anyway, but please do report back on how the fishing was on Snowbird if you go this weekend.