Summer is a great time to go outside and enjoy the sunshine, take a swim, or spend time near local water sources but there are a few things people should do to protect themselves and their pets from water illnesses.

We all like to enjoy our neighboring lakes in the summer, but recreational water illnesses can really put a damper on the summer fun and can be downright dangerous. These water illnesses are the various illnesses caused by germs that can contaminate water in lakes and other natural water sources. When you or your pet swim, you share the water with everyone, and germs are easily spread when swimmers or water enthusiasts swallow contaminated water (even just a little).

Have you heard of cyanobacteria, or blue-green algae? This kind of algal bloom is considered to be harmful and needs to be avoided. Many questions come into play when discussing blue-green algae, such as:

  1. What do blue-green algae blooms look like?
  2. Do they always look the same?
  3. How can you tell blooms apart from their non-harmful look-alikes?

Fortunately, blooms don’t all look alike. Bloom appearances can vary depending on the species present and their concentrations in the water. Generally speaking, the most common bloom conditions seen in Wisconsin result in water that looks like: spilled latex paint, green pea soup, is discolored or streaky, it has small green dots floating in it, floating scum, globs or mats and may have dead fish or other animals floating in it.

Anyone can do these simple, no-cost tests for identifying blue-green algae that are presented by the WI Department of Health Services. Remember to always wear rubber or latex gloves for your protection incase harmful blue-green algae is present.

The Jar Test

  • With gloves on, use a glass jar to collect a sample just below the surface of the water (avoid collecting just the top layer of scum).
  • Fill the jar about three-quarters full (leave room at the top for gas production). Wipe any scum off the outside of the jar and screw the lid on.
  • Leave the jar in a location where the contents will not be disturbed for 2–3 hours.
  • After 2 or 3 hours, observe the jar to see where the algae have settled. Algae that sink to the bottom are likely true algae, and algae that form a greenish ring at the top of the water are likely blue-green algae (cyanobacteria).

The Stick Test

  • With gloves on, push a long, sturdy stick into the surface of the algal material and slowly lift it out of the water.
  • If the stick comes out looking like it has been dipped into a can of paint, the material is likely blue-green algae. If it comes out with long, green, hair-like strands or threads, the material is probably true algae (filamentous green algae).
  • While accumulations of filamentous green algae may be a nuisance in a lake, they are not a health hazard.

These tests may help you determine if you have higher levels of blue-green algae in your lake, but they don’t tell you whether or not the blue-green algae are actually producing toxins. When in doubt, it’s best to keep out!

If you suspect that a lake or water way has a harmful algal bloom, do not swim, wade, ski boat or fish through algal scum and do not let pets drink lake water during an algal bloom, eat algal scum or even lick it off their fur. Always be sure to shower off with soap and water after swimming in a lake. Some common human and animal symptoms are difficulty breathing, lethargy, nausea, vomiting, and diarrhea. Please report any algae-related illness to the Wisconsin Harmful Algal Blooms Program by calling 608-266-1120 or by calling Burnett County Public Health at 715-349-7600.


Submitted by: Anna Treague, RN, Burnett County Public Health

“Healthy Minute” is brought to you by healthyburnett.org


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