Chiggers?? In California I don't think so!! That's more of a south eastern problem! And Wizard, no they can't live under water! Boy they do itch though!! BIG TIME! I just think that the red bump is just a bit larger than you describe for a red bug (better known as Chiggers). There is more of a probability that Bacteria is in the water! I know that the last time I had a soak, down at the springs some 20 yrs ago, I had the same thing happen but it disappeared a day later! Spoke with a doctor friend of mine a couple days after and he told me that, ' it was more likely that it was some bacteria that I picked up while at the springs!' Also, I do remember some 27 years back, if I remember right, that at one time BLM wouldn't issue permits, for a short time, to dredge Deep Creek because of the bacteria in the water. This is something that really needs to be brought to the attention of the BLM, because who knows maybe this is what is killing off the frog the environmentalist Nazi's have been talking about!