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At the height of blue-green algae season: What is it? Should you be worried about it?

blue-green algae at Asylum Point on Lake Winnebago
Posted at 6:40 PM, Jul 20, 2023
and last updated 2023-07-20 19:40:34-04

WINNEBAGO COUNTY (NBC 26) — “The biggest thing is, if you see any algae on the lake, or any possible evidence of that... just stay out of the water,” said Environmental Health Specialist Morgan Peterson.

Peterson works with the Winnebago County Health Department, and she said we are in the middle of a big season for scum.

Specifically, blue-green algae, which is a type of scum.

“From June to September is kind of that season that we have where we see the big scums and the big growth on the lakes,” Peterson said.

She said there are many reasons to want to avoid water with that soupy green growth on it when you see it.

“There can be rashes that can kind of come up. But also if you ingest the water it can cause kind of stomach issues – vomiting, diarrhea – that can be an issue," Peterson said. "But that's why showering after swimming and not drinking the water is the best.”

In Menasha, Heckrodt Wetland Preserve's naturalist Andrea Bierbrauer said it's possible to help limit the growth of this kind of algae by being mindful of the chemicals used in your lawn care.

“Blue-green algae is caused by the additional nutrients in the water by runoff; it's additional phosphorus and nitrogen," Bierbrauer said. "And by thinking about what we're putting in our lawns actually can decrease that.”

She said that your lawn doesn't have to be next to the lake in order to affect it.

“It can run off from your yards down to the sewers and down the — into the waterways. It could be streams, lakes — and then it all kind of runs into Lake Winnebago," said Bierbrauer. "Could come from everywhere.”

She also said wetlands like Heckrodt are one of the natural defenses against scum like blue-green algae.

“When a runoff goes through a wetland such as Heckrodt, it actually filters out that, those extra nutrients,” Bierbrauer said.

Another factor that can encourage blue-green algae growth is still water. So, in drier summers like the one we're currently experiencing, you're likely to see more of it.

"Blue-green algae has like a kind of a soupy look to it," Bierbrauer said. "It's different than your normal, good algae. It's very thick and soupy.

close look at blue-green algae
A close look at "soupy" blue-green algae

It looks different than another type of green that you may find floating on the water in places like Heckrodt: duckweed.

"Duckweed looks like somebody sprinkled confetti," said Bierbrauer. She added that it's the smallest blooming plant in Wisconsin.

duckweed close up
Duckweed is the smallest blooming plant in Wisconsin. It is not toxic or dangerous to touch.

If you believe you, your children, or your pets may be experiencing poisoning symptoms after touching blue-green algae, the Department of Health and Human Services urges you to call them at 608-266-1120 or fill out this online form.

You can also view a map of blue-green algae in the area that updates several times a week.

For more information about blue-green algae, you can visit the Winnebago County Health Department's website.