Hi Arizona Mike! We seem to have agreement that "something has changed" in the water at Deep Creek, but we don't know why. I too had lengthy soaks there in previous years and never experienced a problem. Also, I have never had any rash problems at other hot springs where the flow of fresh water is much weaker than at Deep Creek. You would think that those types of pools would be the ones with bacteria problems. I can offer no explanation why bacteria would be a bigger problem now than it has been in the past.
I'm not a chemist (lemon juice does NOT contain acetic acid, as I wrote earlier, but rather citric acid), bacteriologist or medic. I was thinking about a trip to the springs later this winter, visited this forum and read Katrina's post about the rash. With the lousy weather up here this weekend I had time to do a little Internet research, and the bacteria explanation makes as much sense as any.
Vinegar is often suggested as an nontoxic alternative household cleaner. It is particularly effective as an antibacterial agent. So, if bacteria is indeed the problem, vinegar could be part of the cure. Whether to use vinegar, bleach or any other cleaning agent, or just to do nothing and wait for the problem to disappear naturally...I'll leave that matter for you locals and regulars to decide among yourselves.
Wizard, I've never been to Big Bend Hot Springs since I don't live that far north, but I see on the map that it's quite close to Ingot. I think Big Bend usually gets good reviews, but some of the pools are those in-the-river kind that are inaccessible during snowmelt season.