I'm a long ways from the lake. I've sorta equated chalkbrood with dampness and or shade. I've taken to placeing my hives in full sun whenever I can, and I haven't had any chalkbrood for quite a while. Maybe it's the queens, maybe the heat, maybe just luck. I can't prove it, but I think the hot summer sun slows down the mites some too. It's harder on me workin them in heat with no shade, but I've decided that I'm old enough to slow down or even take a break if I need one.