Part 4 – Harmful Algal Blooms (HABs)

Report blooms to  Need Bloom location with Lake, Town & County Name, size, duration, and photos.

Did you go swimming and start coughing a couple of hours later? Go waterskiing, jetskiing or tubing and feel a little tired? Go boating and feel nauseated? All of these symptoms could be just an everyday thing—or they could be symptoms on contact with potentially-toxic blue-green algae. Many people don’t realize they are having such a reaction because the symptoms mimic common problems.

Blue-green algae are ordinary and necessary for our lakes, streams, and rivers. However, some blue-green algae can become toxic and cause many symptoms (even death in extreme instances) to both humans and animals. Exposure can occur through skin contact, inhalation (breathing in), and/or ingestion (swallowing).

Common human symptoms caused by exposure to these bacteria are:

  • Skin irritations: itchy skin; red skin; blistering; hives; rash.
  • Respiratory Irritations: sore throat; congestion; cough; wheezing; breathing difficulty.
  • General body reactions such as fever, diarrhea, earache, runny nose; vomiting; abdominal pain; nausea; headache; muscle/joint pain; eye irritation; agitation.
  • In severe cases, convulsions/seizures; paralysis, respiratory failure, even death.

To avoid these problems, use common sense. If the water looks scummy, has a large mat of gunk, or otherwise looks iffy, avoid contact. Don’t let children or pets play in shallow, scummy areas or where algae blooms are present. Avoid jet-skiing, water-skiing, or tubing over mats of algae. Don’t use raw, untreated water for drinking, cleaning food, or washing gear. Don’t boil contaminated water, as this may release more toxins from the algae. After family members come into contact with water that may be contaminated, wash thoroughly, especially in areas covered by swimsuits (which may concentrate the algae). Thoroughly wash any clothing or fabric that has come into contact with the water. If your pet or livestock come into contact with such water, wash the coat to prevent the animal from taking potentially-toxic algae in while self-cleaning.

The State of Wisconsin has a program to track negative consequences of contacts with algae. If you think you or others (including pets) have symptoms from such contact, you should call 608-266-1120 or fill out a report on line at You will be contacted shortly by someone from the program to get details and schedule further action.


This series about algae in our waters was written by Lake Specialist Reesa Evans of the Adams County Land & Water Conservation Department. She is also a lake manager certified by the North American Lake Management Society.