PEORIA — The Illinois Environmental Protection Agency and Department of Public Health issued a warning Wednesday about blue-green algae growth in Illinois waterways.

Blue-green algae, also known as cyanobacteria, have been in the news lately for causing dogs deaths around the eastern and southern U.S. The microscopic organisms occur naturally in lakes and streams, and can bloom late in the summer when warmer temperatures and nitrogen run off cause a boost of growth.

While most blue-green algae are a harmless and natural part of the ecosystems, some can produce toxic chemicals which cause sickness or other health effects in people and pets, depending on the amount and type of exposure, the IEPA warns. Residents are urged to use caution when recreating on Illinois waterways, especially at this time of year when blue-green algae blooms are most prevalent. When a blue-green algae bloom has been confirmed, local officials are advised to post appropriate signage to warn residents to avoid contact with affected waters; however, not all blooms are reported to state officials. Residents must be aware and avoid contact with suspicious looking water.

People who plan to recreate on Illinois waters this summer are advised to avoid contact with water that:

looks like spilled green or blue-green paint;
has surface scums, mats, or films;
is discolored or has green-colored streaks; or
has greenish globs suspended in the water below the surface

People are also advised to keep children and pets out of the water. Do not allow pets to drink from the water and do not allow them to lick their fur after swimming in water containing a blue-green algae bloom. If you or your pet has contact with water you suspect may have a blue-green algae bloom, rinse off with clean, fresh water as soon as possible.

Sensitive individuals, including young children, the elderly, and people with compromised immune systems are most at risk to adverse health effects attributable to algal toxins. Individuals are most often exposed to algal toxins while swimming or participating in other recreational activities in and on the water. The most common routes of exposure are direct skin contact, accidental ingestion of contaminated water, or accidental inhalation of water droplets in the air. Symptoms of exposure to algal toxins include rashes, hives, diarrhea, vomiting, coughing, or wheezing. More severe symptoms may result from longer or greater amounts of exposure.

Activities near a lake or river, such as camping, picnicking, biking, and hiking, are not affected. With all activities, wash your hands before eating if you have had contact with lake or river water or shore debris.

If you are concerned you have symptoms that are a result of exposure to algal toxins, contact your health care provider or call the Illinois Poison Center at 1-800-222-1222. If your pet experiences symptoms that may be a result of exposure, contact your veterinarian.

For additional information about harmful algal blooms visit