In early June we began to see the first reports of blue-green algae at area beaches. When confirmed, these sightings require the closing of the beach, which means it is not safe to go in the water.     
 
Up-to-date beach conditions and closure notices
 
Blue-green algae are not actually algae. They are single celled bacteria known as cyanobacteria that use sunlight to make their own food and are among the world’s most ancient life forms.  Their growth which occurs naturally creates blooms that look like large scummy mats that appear on the surface of lakes and rivers, (which probably gave rise to its nickname “pond scum”). They tend to be green to blue-green in color, but can also be reddish-purple, or brown sometimes looking like a coat of paint on the surface of the water.
 
Some of these blooms are capable of producing toxins.  Exposure to these toxins can produce a range of serious reactions, from rashes and lip blistering to harmful effects on the liver and nervous system.  Other reactions can include sore throats, headaches, muscular and joint pain, gastro-intestinal symptoms and asthmatic reactions.  If you believe you have been exposed, wash it off quickly and contact your doctor right away.
 
When you see blue-green algae bloom, stay out of the water.  This means you, your children, and your pets.  Dogs swimming in or drinking water covered with a bloom can suffer near fatal or fatal consequences. This also means avoiding going through patches of blue-green algae when water skiing or using a Jet Ski® type personal watercraft.
 
The only benefit to blue-green algae´s disgusting appearance and smell is that it makes going into the water a clearly unattractive option.  Blue-green algae blooms occur frequently and intermittently throughout the summer season. Spells of hot weather and heavy rains carrying nutrients can create conditions that increase the possibility for increased blue-green algae blooms though they are hard to predict.    Since the lakes are always in motion, the wind and waves that can bring a bloom to a beach are just as capable of blowing or carrying it away.  Blooms can linger for a few hours or days depending on weather conditions. 
 
Unfortunately, there are no quick chemical fixes that we can use to make these blooms go away.  Past experience has taught us that if we try to use herbicides or algaecides, we may succeed in killing the bloom, but as the bacteria die, they will release their toxins into the water and thus create a potentially bigger problem. 
 
Phosphorous and nitrogen fertilizers used in our yards and farm fields run off into our lakes and other waterways, helping to create the conditions that generate the blooms.  Reducing the use of these chemicals could help to decrease the growth of these blooms.
 
PHMDC (Public Health-Madison and Dane County) regularly monitors water quality at many Madison area beaches including routine, testing for harmful bacteria and blue-green algae. If test results show that beach conditions are not safe, the beach will be closed for swimming. Follow-up testing is done every day until the problem clears up.   You can report the appearance of a bloom or illness possibly related to blue-green algae by calling PHMDC at (608) 266-4821.   You can get more detailed information about an exposure by calling the Wisconsin Poison Control Center at 1-800-222-1222.
 
More detailed information on blue-green algae from the DNR
 
More health information on blue-green algae is available at the State Dept. of Health Services
 
For information on blue-green algae from the CDC