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Harmful Algal Blooms (HABs)

Due to the emergence of harmful algal blooms (HABs) in surface water bodies across the United States, the Illinois Department of Public Health (IDPH) and the Illinois Environmental Protection Agency (IEPA) are conducting surveillance to detect HAB events and associated illnesses.

What are Harmful Algal Blooms?

Harmful algal blooms result from a rapid growth, or bloom, of blue-green algae (also known as cyanobacteria). Blue-green algae are a natural component of the aquatic environment in Illinois, but excessive blooms can occur in warm-weather months during calm and sunny conditions. Blooms may appear as a thick scum layer or green paint on the surface of the water, and can be a variety of colors such as blue, green, or brown. There may also be a foul odor present during a bloom. In many cases, excessive blooms are associated with fish kills and animal deaths, most notably dogs. Though these warning signs are often good indicators of a potential bloom, water quality testing must be conducted to determine if toxins are present at harmful levels.

How Can I be Exposed to Harmful Algal Blooms?

Humans are primarily exposed to blooms by incidentally ingesting contaminated water while swimming, wading, or participating in water sports such as canoeing, kayaking, water skiing, or tubing. Exposure can also occur by inhaling water mist while boating or by fishing or eating fish from a contaminated water body. In rare cases, humans can be exposed when untreated surface water is utilized as a drinking water source. You can reduce your exposure to blooms by avoiding waters that are showing signs of a bloom and by washing your body with soap and clean water after swimming in a lake, river, or pond. If your pet has been exposed to a bloom, rinse it with soap and clean water.

How Can Harmful Algal Blooms Affect my Health?

The production of cyanotoxins is what makes a bloom harmful. The most commonly observed and well-known cyanotoxins include anatoxin, cylindrospermopsin, microcystin, and saxitoxin. Exposure to cyanotoxins can cause a variety of harmful effects within hours of exposure. Incidental exposure from swimming or playing in contaminated water may lead to nausea, diarrhea, lethargy, and irritation of the skin, eyes, and respiratory system. Liver damage and death can occur in pets, livestock, and humans when untreated surface water is used as a drinking water source.

What Should I do if I See or Have Been Exposed to a Bloom?

If you see a bloom, avoid the water where the bloom is located and notify IEPA via the Illinois EPA HAB Report Form.

If you or your pet have been exposed to a bloom, immediately bathe using soap and clean water and monitor for symptoms associated with exposure. If you become ill, see a doctor or contact the Illinois Poison Center at 1-800-222-1222. If your pet shows exposure symptoms, such as vomiting, fatigue, stumbling and falling, difficulty breathing, trembling, or unusual drooling, call a veterinarian.

Suspected human or animal cases of HAB-related illnesses should be reported to IDPH via the IDPH HAB Human Illness Report Form or the IDPH HAB Animal Illness Report Form.