Officials have posted signs at a western Ohio state park lake to warn visitors about toxic blue-green algae.
The state Department of Natural Resources posted the first signs of the year Thursday at four beaches in Grand Lake St. Marys.
The Columbus Dispatch reports the signs warn people with weak immune systems to not swim or walk through the water. It also warns elderly and young people to stay away.
Blue-green algae are common in most lakes but grow thick in sun-warmed water that contains phosphorus.
Department spokeswoman Bethany McCorkle says a test on Tuesday of the 13,000-acre lake showed toxin levels higher than the recommended threshold.
Milt Miller, co-founder of the Grand Lake St. Marys Restoration Commission, says those levels are still lower than they were last year.
Information from: The Columbus Dispatch, http://www.dispatch.com