The Onset of Summer Means the Beaches are Open

Thursday, June 13, 2013 - 4:10am

It Also Means it's Time to Watch for Blue-Green Algae

After a seemingly endless cold spring, summer weather has finally arrived. Area beaches were officially open for business on May 25th. Unfortunately, these area beaches may be occasionally closed due to blue-green algae blooms or other types of bacterial contamination.

Blue-green algae blooms are pretty nasty. They are actually a type of photosynthetic (sunlight-loving) bacteria known as cyanobacteria that occur naturally in lakes, streams and ponds, some of which are capable of producing toxins. When water temperature, wind and wave patterns combine with high nutrient levels in the water, they will grow into ugly mats that are most often blue-green in color, but can also be reddish-purple, or brown. The only benefit to its disgusting appearance and smell is that it tends to keep people away. This is helpful since exposure to these toxins can produce a range of reactions, from rashes and lip blistering to sore throats, headaches, muscular and joint pain and asthmatic and gastro-intestinal symptoms.

These blooms tend to appear after heavy rains, meaning that swimming after a heavy rain is not a good idea. When a bloom does appear, PHMDC will close the beach to all swimming. Since winds and currents can make some blooms disappear as quickly as they appear, some of these closings may not be for very long. If you see a bloom, the safest response is to keep yourself, your children, and your pets out of the water. Dogs exposed to blue-green algae can suffer near fatal or fatal consequences.

The good news is that all public beaches in Dane County are monitored by the laboratory at Public Health - Madison & Dane County (PHMDC). During the swimming season the PHMDC laboratory conducts water quality testing at 13 Madison beaches, one UW beach and two Dane County beaches. All other Dane County Beaches are monitored by the Wisconsin Department of Natural Resources (DNR) or by municipalities. PHMDC will also close a beach if the water tests positive for other types of bacterial contamination, often caused by goose and other water bird droppings.

The PHMDC website at, has up-to-date beach conditions including the results of lab testing. The Public Health lab also tests the water of all public and commercial swimming pools in Dane County.

If you believe you have been exposed to blue-green algae, contact your health care provider right away. You should also report this to a lifeguard and call Public Health at (608) 266-4821.

For more information on water health and safety, see

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


Public Health - Madison & Dane County


  • Jeff Golden(608) 243-0302