Officials confirm algal bloom on Illinois River near Starved Rock

Residents should use caution when recreating and be aware of blue-green algae


SPRINGFIELD – Following sampling on the Illinois River, Illinois officials have confirmed the presence of the algal toxin, microcystin, above the 8 parts per billion (ppb) health advisory established by U.S. Environmental Protection Agency. The Illinois Environmental Protection Agency collected samples on June 10 along the northern bank of the Illinois River at the Starved Rock Lock & Dam (Illinois River mile 231.1). The Illinois EPA’s laboratory confirmed the microcystin level in the sample at 95.4 ppb, well above the health advisory limit. Illinois EPA proactively sampled again on June 16 for microcystin and awaits the results of the resampling event.

Algal toxins (e.g., microcystin and cylindrospermopsin), sometimes produced by blue-green algae, can cause sickness or other adverse health effects in people and pets, depending on the amount and type of exposure. Illinois EPA also tested for cylindrospermopsin, anatoxin, and saxitoxin but did not detect their presence near any level of concern.

The very young, elderly, and people with compromised immune systems are most at risk of illness if exposed to algal toxins. Adverse health effects attributable to algal toxins can occur from direct skin contact, swallowing contaminated water, or inhaling water droplets in the air. Symptoms of exposure 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 your health care provider or call the Illinois Poison Center at (800) 222-1222. If your pet experiences symptoms that may be a result of exposure, contact your veterinarian immediately.

Residents who plan to recreate in, on, or near Illinois rivers, lakes or streams 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
  • has greenish globs suspended in the water below the surface

Do not let pets drink from or swim in water with any of the above characteristics.

If you or your pet have come into contact with water you suspect may have a bloom of blue-green algae, rinse off with clean, fresh water as soon as possible. Do not let pets lick scum from their fur. With all activities that may involve contact with lake or stream water, wash your hands before eating.