Lake Winnebago Water Quality Advisory for Blue-Green Algae

Winnebago Health Department declares a WATER QUALITY ADVISORY for Lake Winnebago due to blue-green algae blooms.  Visual and laboratory confirmation by the WI-DNR indicate high concentrations of blue-green algae on some Lake Winnebago west shore areas in Oshkosh.  Blue-green algae may also be impacting other areas so it is important to look at the water before entering, particularly before letting children and pets go in the lake.




If you suspect a child or pet has ingested contaminated water, contact your medical provider or veterinarian immediately.  Blue-green algae may produce a toxin that is harmful to health.  The DNR and Winnebago County Health Department are posting this advisory at common Lake Winnebago access points.


We recommend common sense measures for safe water recreation practices if blue-green algae are present:


  • If you wade into knee-deep water without disturbing the sediments and you still see your feet, the risk of illness from swallowing or inhaling blue-green algae in water is moderate to low.  You should still avoid swallowing untreated surface water, as other bacteria, viruses, or parasites may be present.
  • If you can't see your feet in knee-deep water, algae densities are elevated and there is a high risk of illness from swallowing or inhaling blue-green algae.  Avoid swimming in these conditions, if water has an opaque, pea soup-like appearance, or if surface scums or foams are present.  Keep small children and dogs out of the water.
  • Avoid boating, water skiing, or jet skiing through waters that are opaque, pea soup-like green or if surface scums or foams are present, to avoid inhalation of blue-green algae in water droplets.
  • Shower after swimming in any body of water, and wash dogs off as well, before they can groom themselves.


There's more information, including a YouTube video about blue-green algal blooms, at the DNR's blue-green algae page at


If you have any questions about the health effects of exposure to blue-green algal blooms, please see the DHS blue-green algae website at  If you have general questions about blue-green algal blooms, please see the DNR's blue-green algae page at



Check out the information on our Blue-Green Algae page.


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