Wisconsin Department of Natural Resources officials are warning swimmers and boaters to watch out for blue-green algae blooms.
DNR officials say bloom reports typically spike in August because the water has warmed up and conditions are most conducive for the growth of blue-green algae blooms.
"August has typically been when we receive the most bloom reports because the water is usually the warmest and conditions most conducive to fueling algae growth." says Gina LaLiberte, Wisconsin Department of Natural Resources research scientist and statewide blue-green algae coordinator.
Some species produce toxins that can cause a range of ailments, including stomach aches, flue-like symptoms, rashes and hives.
Blue-green algae, technically known as Cyanobacteria, are microscopic organisms that are naturally present at low numbers in all Wisconsin lakes, streams and ponds.
When conditions are favorable, usually in summer, the number of algae can increase dramatically, appearing as opaque, pea-soup-like water or forming colorful scums.
Some algal species produce toxins that, when ingested or inhaled, can cause illness in people, pets, livestock and wildlife, LaLiberte said in a statement.
Gastrointestinal upset from swallowing toxins in water and flu-like or asthma-like symptoms from inhaling algae in water droplets are the most common symptoms reported to the Wisconsin Harmful Algal Bloom Surveillance Program, said Emmy Wollenburg, Outreach Specialist at the Wisconsin Department of Health Services.
"People may also experience rashes and hives from skin contact with blue-green algae, particularly if they are susceptible to other allergic reactions," Wollenburg said.
The worst illnesses are usually seen in animals like dogs, which aren't concerned about water quality and may swim in or drink from water with significant blue-green algae blooms, Wollenburg said.
"Dogs also are at risk because they may ingest algae when they groom themselves after swimming, which is why it's so important to rinse your pet with fresh clean water every time they swim in a lake, pond or river," she said.
When blue-green algae appear as scums on the surface of the water, pea-soup like water discoloration, or a paint-like sheen, this indicates impaired water quality, according to LaLiberte.
"A good rule of thumb for assessing algae levels is that if you walk into the water up to your knees - being careful not to kick up the bottom sediments - and you can see your feet, the risk from blue-green algae is low to moderate, but it's still a good idea to avoid swallowing water," LaLiberte says.
"When you can't see your feet, keep children and dogs out of the water, and consider having the whole family pursue another activity that day," she said.
It's also a good idea to always wash hands before eating, and wash off after swimming in any lake or and pond to reduce the chance of irritation or allergenic effects.
And people should not forget about pets that have been playing in the water. Rinse off pets with clean water to prevent them from ingesting blue-green algae accumulated on their fur.
"Dogs also are at risk because they may ingest algae when they groom themselves after swimming, which is why it's so important to rinse your pet with fresh clean water every time they swim in a lake, pond or river," Wollenburg said.
If a pet displays symptoms such as seizures, vomiting, or diarrhea after contact with surface water, contact a veterinarian right away.
People who think they are experiencing symptoms related to exposure to blue-green algae - stomach cramps, diarrhea, vomiting, headache, fever, muscle weakness, difficulty breathing - should contact their doctor or the Wisconsin Poison Center at 800-222-1222.
To report illnesses that may be related to blue-green algae, contact the Wisconsin Department of Health Services at 608-266-1120, or fill out an online survey on its website. Go to www.dhs.wisconsin.gov and search for "blue-green algae"