Illinois e-News Release

June 03, 2024

Kim Biggs (IEPA) – 217-558-1536

Jim Leach (IDPH) – 217-785-9209

Michael Claffey (IDPH) – 312-814-4669

SPRINGFIELD – In anticipation of seasonal weather and higher temperatures, the Illinois Environmental Protection Agency (Illinois EPA) and Illinois Department of Public Health (Illinois DPH) are issuing an annual reminder for individuals to use caution when recreating on or in Illinois waterways, as harmful algal (cyanobacteria) blooms are possible on any body of water. Cyanobacteria, also known as blue-green algae, are microscopic organisms that naturally occur in lakes, streams, and ponds. A “bloom” can occur when cyanobacteria have a rapid and expansive growth. While most blooms are harmless, some produce toxic chemicals that can cause sickness or other adverse health effects in exposed people and pets.

Residents can find information on the Illinois EPA’s 2024 Harmful Algal Bloom Program through the Illinois EPA’s website. The program includes routine monitoring at lakes and lake beaches throughout Illinois. In addition, “Event Response” investigates credible reports of a potential cyanobacteria bloom. A credible report refers to a direct observation by Illinois EPA staff or observations and pictures submitted by the public to Illinois EPA. In 2023, Illinois EPA created the new online Harmful Algal Bloom Dashboard that displays information submitted through the public Illinois Bloom Report Form and has a map of blooms that have been reported to Illinois EPA, investigated, and confirmed. Two blooms have already been posted for 2024.

If a bloom producing toxins is confirmed, local officials are advised to post appropriate signage to warn residents to avoid contact with affected waters. However, it is important to remember that not all blooms are reported to state officials. Therefore, residents are advised to avoid contact with a body of water that:

• looks like spilled green or blue-green paint;

• has surface scums, mats, or films;

• has a blue or green crust at the shoreline;

• is discolored or has green-colored streaks; or

• has greenish globs suspended in the water below the surface.

Examples of cyanobacteria blooms can be found at: https://epa.illinois.gov/topics/water-quality/monitoring/algal-bloom/identifying.html

Residents or local officials who suspect a cyanobacteria bloom may report the bloom to the Illinois EPA through the Bloom Report Form App, which is accessible by computer or phone. The App and other reporting methods are available on the Illinois EPA website at https://epa.illinois.gov/topics/water-quality/monitoring/algal-bloom/reporting.html.

Individuals most at risk for adverse health effects attributed to algal toxins include young children, the elderly, and individuals with compromised immune systems. Individuals are most commonly 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, ingestion of contaminated water, or inhalation of water droplets in the air (e.g., while water skiing or tubing). 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. If you are concerned you have symptoms that are a result of exposure to algal toxins, contact a health care provider or call the Illinois Poison Center Helpline at 1-800-222-1222.

Residents are also advised to keep pets out of water that may contain cyanobacteria. Do not allow pets to drink from the water, swim in the water, or lick their fur after being in contact with water containing a cyanobacteria bloom. Residents and pets that have contact with cyanobacteria should rinse with clean water as soon as possible. If pets experience symptoms that may be the result of exposure, residents are advised to contact a veterinarian immediately.

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

For additional information about harmful algal blooms, please visit the Illinois EPA Harmful Algal Bloom website:

To report a human or animal illness from harmful algal bloom exposure, please visit the Illinois DPH Harmful Algal Bloom website: