Blue-green Algae in Wisconsin
5 confirmed blue-green algae reports in Wisconsin, 2 still active. About this disease: symptoms and prevention.
5
Reports on record
2
Currently active
0
Last 7 days
2
Last 30 days
Where in the state
2
1
1
Recent reports
Blue-green Algae
Active · Aug 21, 2026
East Troy
Booth Lake, Town of Troy, Walworth County; microcystin confirmed, state investigated 9 illness reports; elevated toxins expected through swim season
Source ↗Blue-green Algae
Active · Aug 13, 2026
Mosinee, Marathon County
Lake Du Bay, advisory re-issued 8/13, spans Marathon and Portage counties
Source ↗Blue-green Algae
Historical · Jul 21, 2026
Oshkosh, Winnebago County
Lake Winnebago (South Asylum Bay, Menominee Park)
Source ↗Blue-green Algae
Historical · Jul 21, 2026
Green Lake, Green Lake County
Green Lake (Sunset Park & County K Marsh boat launch)
Source ↗Blue-green Algae
Historical · Jun 16, 2026
Mosinee, Marathon County
Big Eau Pleine Reservoir (park beach)
Source ↗