How to spot them
From the U.S. Centers for Disease Control: Look for “a foam, scum, or mats on the surface of fresh water lakes and ponds. The blooms can be blue, bright green, brown, or red and may look like paint floating on the water. Some blooms may not affect the appearance of the water. As algae in a cyanobacterial bloom die, the water may smell bad.”
If you spot them
- Call the authorities. Kirsti Sorsa at Madison and Dane County Public Health: 243-0356. Around the state: Check the DNR’s frequently asked questions about blue-green algae for relevant phone numbers.
- If it’s a swimming area, collect a water sample. “It doesn’t have to be sterile,” Sorsa said.
- Try a different beach. Water quality can vary a lot around a lake. “People think that if one beach is closed, the whole lake is in bad shape,” Sorsa said. “There are lots of good places to swim.”
Algae and illness
Cyanobacteria don’t always produce the toxins that make people sick. The toxins vary in their toxicity and what they damage — some are neurotoxins that affect the central nervous system, while others damage the liver. Symptoms may not show up immediately, said Sorsa.
Signs of illness in people: Respiratory symptoms include sore throat, cough, wheezing, trouble breathing and irritated eyes. Skin may become itchy, red or blistered, or hives may appear. Other symptoms can include agitation, headache, abdominal pain, diarrhea or vomiting, according to the Wisconsin Department of Health Services.
Signs of illness in pets: Lethargy or weakness, difficulty breathing, diarrhea, seizures or vomiting. Pets and algae: fact sheet from DHS.
Where to report potential illness: Online, use the DHS’s Algae-Related Illness Report Form. Or call DHS at 608-266-1120.