Public Health Madison & Dane County: Stay away from blue-green algae blooms

Contact: Sarah Mattes
(608) 216-3202
(608) 266-4821

Blooms can cause illness and should be avoided

Over the last few days, widespread areas of blue-green algae (cyanobacteria) have been spotted throughout Madison area lakes. Public Health Madison & Dane County (PHMDC) advises residents to avoid coming into contact with algal blooms.

Blue-green algae blooms may cause illness for those who accidentally ingest or inhale water containing algae, or have prolonged skin contact with the algae. The blooms produce toxins that can cause symptoms such as stomach upset, rashes, and respiratory irritation. Dogs that come into contact with algal blooms can also get sick and sometimes die because their bodies are smaller and they tend to swallow a lot of water. Both people and pets should avoid being in water where algal blooms are present.

Harmful blue-green algal blooms vary in their appearance, looking like scum, foam, or a mat, and despite their name, can be different colors. Lots of nutrients (phosphorus and nitrogen), sunlight, high water temperatures and calm wind levels usually allow them to grow.

Although they are likely denser near the shoreline, blooms are likely present in the middle of the lakes as well and should be avoided by boaters. Should people discover they are in the water near a bloom, it is important that they avoid swallowing water and that they rinse off well when they get out.

If people have symptoms they think are due to contact with blue-green algae blooms they should call their healthcare provider or the Poison Control Center at 1-800-222-1222. Dogs that have been in water near a bloom should also be rinsed well and a vet should be called if they seem ill after.

A current listing of beaches that are closed due to blue-green algae and bacteria can be found on the PHMCD website. Before swimming, always take an overall look at water conditions. Conditions can change quickly, and testing results may not always reflect real-time water quality.

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