McHENRY – Petersen Park Beach is closed because of an unsightly, foul-smelling algae bloom caused by high temperatures and a lack of rain.
The area was treated with herbicides in the spring to remove Eurasian milfoil, McHenry Parks and Recreation Director Peter Merkel said. The treatment caused the weeds to die, decompose and wash ashore.
Combined with record-high temperatures and severe drought, blue-green algae fed off the nutrient-enriched water and weeds to create the bloom.
McCullom Lake also is down about a foot in depth compared with last year in that area, Merkel said. The majority of the problems are on the west shoreline near Petersen Park Beach and Hickory Creek Farm, and the area near the village of McCullom Lake.
“It is a shallow lake already and has warmed up very quickly,” Merkel said. “We have been dealing with this for more than a month now, and cleaning can’t keep up with the weather.
Eurasian milfoil is an aggressive, non-native species that chokes out native plants. It can become so dense that it restricts boating, fishing and swimming.
The blue-green algae blooms, also known as cyanobacteria, are common in the region, said Kevin Irons, aquatic nuisance species coordinator for the Illinois Department of Natural Resources.
“We are just in a bad situation,” he said. “It really blossoms when you have hot weather, a lack of winds and a lack of clouds. That’s exactly where we’ve been at the last three weeks.”
Pets and residents should stay out of the water where blooms are, Irons said.
Symptoms of blue-green algae poisoning in humans include rashes, gastrointestinal pain and respiratory irritation.
Animals are at a higher risk because of the possibility of ingesting the water. Their symptoms include loss of appetite or vomiting, among others.
The beach, at 4300 Petersen Park Road, will be closed for the foreseeable future. Reopening is dependent on the weather. Water needs to be circulated from the bottom of the lake to the top.
“There has been no influx of freshwater to help with this situation,” Merkel said. “We can try and control it the best we can, but we can’t eradicate it.”