Thanks for the water test results. "Normal" total alkalinity is 80-120. Prolonged exposure to higher levels of alkalinity (like at Deep Creek) is a knoown skin and eye irritant.
So Wizard's (and others) rashes are likely from sitting in the pools for a long time and being exposed to the high alkalinity of the waters.
The other conceivable option is the bacteria present, especially if the water tests positive for fecal coliform.
Bottom Line: We can all keep soaking, just don't stay in the pools for do long!