I agree with that, East Bay, and like your proposal for cleaning the pools without using anything chemical. Vinegar sounds safe enough to me, but I'd prefer to see what the forest service thinks about it first, in case there is something I don't know.
DCV hasn't been able to meet for two months, but I'm hoping we will meet in January. I can make it, and so can Paul.
Speaking of Paul, he just suggested that another theory might be from a leaf or two of poison oak or sumac getting into the water, which might produce a milder and more temporary rash. Sounds like bacteria to me, though.