Totally common round here. Nothing works that I've found. I'm really sensitive to it, so generally avoid the lake.
For whatever reason... I tend to NOT get it when I'm swimming with my dog. Don't know why ... Something he's excreting in the water, maybe? Cleaner water for sure in dog beaches than people beaches (microbe and parasite counts are about 1/8th in the dog beaches as opposed to people ones, here, anyways. I tend to escape the itch BOTH at the dog park AND of private property with him. (So its not the groups of dogs keeping birds and raccoons away, although I'm sure that helps. Ditto a smaller food source because there are so few people). But again... I have no real idea.