Blue-green algae is harmful to humans and pets

It is a bacteria that can make people and animals sick by touching or even inhaling it
Updated: Aug. 8, 2022 at 6:30 PM CDT
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MOSINEE, Wis. (WSAW) - While coming across algae at the lake is unpleasant, certain types can even be dangerous. Marathon County Health Department said August is usually the peak time for algae blooms. That includes blue-green algae, which isn’t technically algae.

“It looks like algae, but it’s actually a bacteria,” said Dale Grosskurth, Marathon County Health Dept.

It looks similar to true algae, but it might have a surface film. There could be green dots floating below the surface, too.

“Blue-green algae will look like green paint on the surface. It will look very liquid like a scum,” said Grosskurth.

It can also have a distinct smell like fishy or gasoline. Telling harmful algae apart from true algae is challenging. Click here to find photos to help you identify the difference. There are lookalikes and water testing isn’t effective for long.

“It takes several days to get the results back on a sample after it’s gotten to the lab. And in that time period the water may have moved on,” said Grosskurth.

You can do some tests of your own. Use gloves to scoop some of the algae and water into a jar. Wait a few hours and true algae will settle to the bottom while blue-green algae will create a green ring floating at the top.

You can also do a stick test. Scoop the algae and if it appears to be hairlike strands, it’s likely true algae. If it looks like spilled paint, it’s likely blue-green algae.

“If it looks questionable, please stay out,” said Grosskurth.

Touching or inhaling it can cause serious symptoms like voting, cough, diarrhea and skin rash.

“Shower or rinse off as soon as possible. And you should also monitor your symptoms the days and hours following exposure,” said Jordan Murray, University of Wisconsin water resources science policy fellow at the Wisconsin Department of Health Services.

If your symptoms continue, you should contact a doctor. You can report symptoms to the Department of Health Services by calling 608-266-1120.

Blue-green algae is also harmful to pets. If they drink it or are exposed too long, it can even kill them. Make sure you wash your pet immediately, monitor symptoms and call a veterinarian if you have concerns.

Sites to learn more about blue-green algae.

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