Between Memorial Day and Labor Day, Public Health Madison & Dane County monitors conditions and tests the water at local beaches to make sure they are safe for swimming.

“During the summer months, harmful bacteria and toxins can be lurking in the water and it can sometimes be hard to know if it’s safe by simply looking at the water,” says Jennifer Lavender-Braun, Microbiologist for Public Health Madison & Dane County. “That’s why we have a rigorous water monitoring protocol during swimming season.”

Nearly two dozen Dane County beaches are sampled for the presence of E. coli bacteria and blue-green algae every week. Crews run the samples through various tests and then check the results, a process that takes about 18 hours. If unsafe levels of bacteria are detected, the beach is closed and staff will retest the water each weekday until levels return to normal.

“In addition to posting signs at the beach, we update our website with the test results and closures daily, and you can sign up for email updates to ensure swimmers can check the status before heading to the beach,” says Lavender-Braun. “Conditions can change quickly, so we strongly encourage you to stay away from the water if you notice blue-green algae blooms or if the water appears murky, even if you don’t see any closure signs up.”

When conditions are just right, blue-green algae can grow very quickly. Do not swim in water that looks like "pea soup", green or blue paint, or that has a scum layer or puffy blobs floating on the surface.

If you suspect your pet has been exposed to blue-green algae, contact your veterinarian right away. Monitor your pet for symptoms of exposure including vomiting, diarrhea, seizures, disorientation, drooling, or trouble breathing.

“Dogs that come into contact with blue-green algae blooms can get very sick, and sometimes die because their bodies are smaller and they tend to swallow a lot of water,” says Lavender-Braun.

Report a blue-green algae bloom or illness to the Wisconsin Harmful Algal Blooms Program (WI DHS) or contact Public Health at (608) 266-4821.