Friend of mine who runs an outdoor supply store here in VA is saying that the Dept. of Game and Inland Fisheries may outlaw felt bottom waders to try and stop the spread of the Didymo Algae in our trout streams.
A research biologist from App State spoke at my TU meeting last year. He's studying didymo right now. We asked about felt vs rubber soles and he just laughed. Told us it only takes a few dozen diatoms for it to spread to a new system. The trouble is, these diatoms are microscopic. So even if you clean your rubber bottoms, it could be very well hiding in the nooks and crannies of your laces or anywhere else. He also said the spread of it probably isn't so much because of anglers. Rather, it's already been in these streams but something about the water has prevented it from blooming. But whether through pollution, ph change, temperature change, etc., the previously unseen colonies are beginning to bloom. So basically, there's extremely little you as an angler can do to stop the spread. That's why Simms started selling felt bottoms again. It gives the gov't control and revenue opportunities to get involved, and so they do, not because the science is solid (his words, not mine).