The Ohio Department of Natural Resources is warning visitors to avoid touching any blue green algae they see in the water at Dillon Lake.
Some campers had been swimming earlier in the week and are now wondering how serious it actually is.
"I wasn't very happy about it, knowing that we were already in it, my kids were in it, and you know, I didn't know what kind of reaction we'd have if you got in contact with it, so it kind of made me nervous," said camper, Josh Dunlevey.
Visitors are still allowed into the park but are advised to use caution for recreational activities at the lake.
"Just going to be camping out I don't think we're going to be going swimming, find something else to do," said camper, Joe Butler.
Samples collected from the lake are being analyzed to see if any algal toxins are present.