City posts advisory on Shadow Lake
Swimmers report becoming sick
By James Card
The city of Waupaca issued a swim advisory for the South Park beach on Shadow Lake.
On Friday, June 24, swimmers complained of feeling ill.
The symptoms were vomiting and gastrointestinal pain.
The next day, the city of Waupaca and the Waupaca County Health Department posted swim advisory signs around the beach area and briefed lifeguards on the situations so they could inform the public.
The Waupaca County Health Department took water samples on the same day as the complaints.
Test results showed that bacterial levels were below standard levels.
They also surveyed for blue-green algae but there were no indications that it was present.
Blue-green algae isn’t a true algae but it is the common name for cyanobacteria, a type of bacteria that thrives in warm water. It appears like algae when it spreads and it looks like a slick of green paint or pea soup. It is often referred to as “pond scum.”
Sometimes these blooms can be large and other times they are not visible.
Although the presence of blue-green algae was not discovered, the water tests represent a snapshot for the particular conditions when the samples were taken.
According to a Wisconsin Department of Natural Resources (DNR) fact sheet, blue-green algae can appear quickly: “Even if you can’t see blue-green algae floating on the surface of the water, that doesn’t mean they aren’t there. Blue-green algae can be suspended at various depths in the water, and their location depends on a number of factors.
“The most important of these are light and nutrients (phosphorus and nitrogen).
“Many species of blue-green algae have evolved to be able to control their buoyancy as the availability of light and nutrients change with the time of day and local weather conditions.
“At night, when there is no light, cells are unable to adjust their buoyancy and often float to the surface, forming a surface scum. So this scum can literally appear overnight and may linger until wind and waves scatter the cells throughout the water body.”
The city staff has done extra cleaning at the beach facilities and individuals who complained of feeling ill are to be tested.
Swimming lessons scheduled for the June 28-30 are rescheduled for July 5-7.
The lessons for the next group of swimmers scheduled to start on July 1 is rescheduled for July 18.
On Wednesday, July 29 there were no swimmers at the South Park beach.
However, there were multiple anglers fishing from boats, the shoreline and docks, and there were a handful of kayakers and stand-up paddle boarders enjoying Shadow Lake.
The lifeguards were keeping busy shoveling sand and tidying up around the facility.
This report will be updated as more information comes available.