Illinois residents should be cautious of algae blooms in waterways

Some cyanobacterial blooms can produce toxic chemicals

As warmer weather approaches, the Illinois Environmental Protection Agency and the Illinois Department of Public Health have issued a reminder to residents to be cautious if they are planning activities on Illinois lakes and rivers throughout the summer.

Water conditions are ideal for cyanobacterial growth. Cyanobacteria, or blue-green algae, are microscopic organisms that naturally occur in lakes, streams and ponds.

Most areas of rapid growth of the cyanobacteria are harmless, however, some can produce toxic chemicals that cause sickness or other health effects in people and pets depending on the amount and type of exposure.

Sensitive individuals including young children, the elderly and people with compromised immune systems are most at risk to adverse health effects from the toxic chemicals.

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, contact your health care provider or call the Illinois Poison Center at 1-800-222-1222.

Residents are asked to use caution when using Illinois waterways for recreation as cyanobacterial blooms are possible throughout the year. Residents are asked to avoid contact with water that:

  • Looks like spilled green or blue paint
  • Has surface scums, mats or films
  • Has a blue or green crust as the shoreline
  • Is discolored or has green-like streaks
  • Or has greenish globs suspended in the water surface below

Do not allow pets to drink from water or allow them to lick their fur after swimming in water containing a cyanobacterial bloom.

If you or your pet has contact with water you may suspect may have a cyanobacteria bloom, rinse off with clean water as soon as possible.

For more information about harmful algal blooms visit the IEPA’s Harmful Algal Bloom website at