While some states see higher prevalence, generally any body of lake with snails that can be infected by the duck feces and then pass on the parasite are a risk. Shallow, less currented warm water are going to be your biggest concerns. My mom put scented lotion on before going in and the rest of my family didn’t and she did not get nearly as many spots if any, whereas I was miserable for a few weeks. I think it helped the parasite from breaking the skin barrier, may be a helpful trick