Lakes-L Blog News Blue Green Algae in Lake Kegonsa


Wisconsin Dept. of Natural Resources & Public Health Madison & Dane County

Blue-Green Algae Blooms Trigger Health Reminder

Avoiding Contact is the Safest Approach



Susan Graham,

DNR Lake Management Coordinator, Fitchburg:

(608) 275-3329


Jeff Golden

Public Health Madison & Dane County

608) 243-0302




Madison, WI – June 30, 2010 – Recent warm weather has fueled the growth of noxious blue-green algae on Lake Kegonsa and this has prompted the Department of Natural Resources and Public Health Madison & Dane County (PHMDC) to remind folks to avoid swimming in areas blanketed with this type of algae.


On the morning of June 29, most of the lake’s surface area was reported to have been supporting heavy blue green algae growth which can have a paint slick or pea soup like appearance,” noted Susan Graham, DNR Lake Management Coordinator based at Fitchburg.  She added that such blooms can be a moving target, since wind and wave action can often make a bloom disappear or appear quickly. 


Bluegreen algae, technically known as Cyanobacteria, are microscopic organisms that are naturally present in Wisconsin lakes, streams and ponds at low levels. When conditions are favorable, massive blooms can appear. According to Kirsti Sorsa, PHMDC’s Public Health Laboratory Manager, “some species produce toxins that, with exposure, can harm the skin (rashes, lip blistering), liver or nervous systems of people, pets, livestock and wildlife. It can also produce sore throats, headaches, muscular and joint pain and gastro-intestinal symptoms.”   In rare cases, the toxins can be fatal to animals although not all blue green algae produce toxins.  Anyone who is experiencing such symptoms should contact their clinic or physician.  They can report this exposure to PHMDC at 266-4821, and to the State Department of Health Services at this link:


With the upcoming July 4th weekend, now is the ideal time to remind people that the presence of blue-green algae in a lake or pond is a marker for a potential hazard,” said Graham. 


Health officials advise people to avoid swimming in areas of lakes and ponds where a scum or mat of algae is present on the water. People also should keep their children from playing in the water, and keep their animals from drinking or swimming in the water with visible blue-green algal blooms.


“Heavy rainfall causing nutrient rich runoff coupled with sunny calm days  create ideal conditions for the growth of heavy blue green algae blooms,” according to Graham.


Blue-green algae blooms are common in Wisconsin, with its 15,000 lakes; about 44,000 miles of flowing rivers and countless small ponds.   The presence of the algae does not mean the water is toxic, but large, unsightly blooms with a blue-green cast serve as a warning that blue-green algae are present and may be producing toxin, potentially at concentrations that could be a health threat.


The World Health Organization advises that people who choose to eat fish taken from water where blue-green algae bloom is present to consume such fish in moderation and avoid eating fish guts, where accumulation of toxins may be greatest. Also, anglers should take care to not cut into organs when filleting fish and rinse fillets with clean water to remove any liquids from the guts or organs before freezing or cooking.


For more information on blue-green algae, check out the DNR’s website at

or the state Department of Health Services website at


For updated information on the conditions at Madison and Dane County beaches, check out PHMDC’s beach information website at:



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