The recent hot, humid weather is fueling blue-green algae blooms on some popular Wisconsin lakes. These blooms can produce harmful toxins (known as cyanotoxins), which can cause illness in people and their pets. There have been a number of reports of algae-related health concerns, and state and local public health and water quality officials are warning the public to avoid swimming, wading, skiing or coming into contact with lake and pond water where a green to bluish-green scum or mat of algae is present.

Gina Egan, Vilas County health officer, is asking families to make sure their children and pets do not swim in or drink scummy lake water. The public is also encouraged to report potential algae-related illnesses to the Wisconsin Department of Health Services by filling out an electronic form found at www.dhs.wi.gov/eh/bluegreenalgae or by calling (608) 266-1120.

Blue-green algae, technically known as cyanobacteria, are microscopic organisms that are naturally present in Wisconsin lakes, streams and ponds at low levels.

When conditions are favorable, usually in summer, the number of algae can increase dramatically, forming pea-soup blooms and scums on the water surface.

Some algal species produce toxins that, when ingested, can harm the neurological systems or liver of people, pets, livestock and wildlife. Not all cyanobacteria produce toxins, but the presence of blue-green algae in a lake or pond is a marker for a potential hazard.

Individuals who experience health effects related to blue-green algae often report rashes, gastrointestinal upset, respiratory irritation and eye irritation.

“Dogs are particularly at risk of illness because they do not naturally avoid scummy water and they can ingest algal material when they groom themselves after swimming,” said Egan.

The Wisconsin Department of Health Services and the Wisconsin Department of Natural Resources advise the following:

• Avoid areas of water that look like paint or pea soup or where algal scums or mats are present

• Always shower with soap after swimming in a lake and wash hands after coming in contact with lake water

• Don’t let pets drink lake water; wash a pet with clean, fresh water after he or she swims in lake water

For more information on blue-green algae, log on to www.dhs.wisconsin.gov/eh/bluegreenalgae/ or dnr.wi.gov/lakes/bluegreenalgae/.