Blue-Green Algae
Blue-green algae, also known as cyanobacteria or “pond scum,” are naturally found in waterways in Wisconsin at low levels. When conditions are just right blue-green algae can grow very quickly in number, producing a scum layer or mat on the surface of water. Blooms typically occur during the warm weather months between mid-June and mid-September. People may be exposed to blue-green algae through contact with the skin, inhalation, or by swallowing contaminated water.

Exposure to blue-green algae blooms may cause: sore throat, congestion, cough, wheezing, difficulty breathing, eye irritation, itchy skin, red skin, hives, earache, headache, abdominal pain, diarrhea, and vomiting. Animals can also become ill from blue-green algae blooms.To protect pets from algae blooms do not let animals drink lake water during algae blooms. Keep animals out of green water or where you see foam, scum or mats of algae; and rinse animals off immediately if they are exposed to algae. Do not let them lick the algae from their fur.Since it is very difficult to tell whether algae blooms are toxic without lab analysis of the water; the safest thing to do is to treat every algae bloom as if it could be dangerous.

Safety Tips:
  • Do not swim in water that looks like “pea soup”, green or blue paint or that has a scum layer or puffy blobs floating on the surface.
  • Do not boat, water ski, etc. over such water.
  • Do not let children play with scum layers, even from shore.
  • Shower and wash hands after swimming in lakes, rivers and ponds.
  • Do not fish from lakes where algae scum is present.
  • Do get medical treatment right away if you think you, your pet or livestock might have been poisoned from algae toxins.
  • Do pay attention and respect water body closures and health advisories.
If you think you are experiencing symptoms related to exposure to blue-green algae (e.g., stomach cramps, diarrhea, vomiting, headache, fever, muscle weakness, difficulty breathing), contact your doctor or the Poison Information Hotline (800-222-1222) right away. If your pet displays symptoms such as seizures, vomiting, or diarrhea after contact with surface water, contact your veterinarian immediately. To report a blue-green algae bloom for more information contact Lincoln County Health Department at 715-536-0307.


Additional Resources
WI DHS "Blue-Green Algae"
WI DNR "Blue-Green Algae"
CDC "Harmful Algal Blooms"