It's not AMD on those streams, it is acid rain fallout. Elk County is reknowned for that problem. Lot's of streams where the trout move out quickly in search of better water, not just the Millstones.
Still, more than just the state stocks streams in that area. You will catch, brook, brown or rainbow there.
It will be fairly busy fishing that weekend. Wouldn't be difficult finding good fishing closer to St Marys unless you just wanted to fish those two streams in particular.
The lower reaches of the Millstones are known to have rattlers also, not saying you're def going to run into them but I'd keep an eye open. Good luck.