Lake Superior has seen half dozen blue-green algae blooms this year

A short-lived blue-green algae bloom was spotted on Friday, Sept. 10, 2021, at the Barker's Island beach area in Superior.

Blooms Were Minor But Underscore Troubling Changes For The Lake

A decade ago, a blue-green algae bloom had never been reported on Lake Superior. Now, half a dozen blue-green algae blooms have been reported this summer across Lake Superior, including one that formed recently in Superior. But researchers say the blooms were relatively minor. 

The Wisconsin Department of Natural Resources is aware of six blooms reported across the lake with five observed during the month of July and one that occurred on Sept. 10, at the Barker's Island beach area in Superior. 

"In general in Lake Superior, the conditions where you would typically see blooms occurring in the lake would be if you had really calm conditions," said Gina LaLiberte, the DNR's harmful algal blooms coordinator. "So, any cyanobacteria, or blue-green algae, in that lake water can then float to the surface, and it can be accumulated near shores if wind is blowing towards shore."

LaLiberte noted the bloom observed in the Barker’s Island beach area formed in a more protected spot, creating calm conditions that allow blue-green algae to build up. 

The Thunder Bay District Health Unit reported the lake's first bloom on July 9 in Black Bay within the Canadian province of Ontario. Nearly a week later, University of Minnesota-Duluth scientists, the Minnesota Pollution Control Agency and a National Park Service ranger observed four blooms in and around Duluth and within the Apostle Islands sea caves during the weekend of July 17-19. 

Blue-green algae often looks like pea soup or spilled paint as it collects near the shore. The scum can produce toxins that can make people or animals sick. LaLiberte said state health officials haven't received any definitive reports of illnesses linked to blooms on the lake this year.

The public has reported around 160 blooms statewide this year — not all of which were blue-green algae.

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