Lake Catherine. | Photo via Compass Real Estate.

Health officials are warning residents to be careful when swimming in Lake Catherine in Antioch after more than 47 times the normal amount of algal toxin was detected in the lake.

The Lake County Health Department Ecological Services Division was notified of blue-green algae bloom on Lake Catherine in unincorporated Antioch, according to Emily Young, the Interim Marketing and Communications Manager for the Lake County Health Department.

Cyanobacteria, also known as blue-green algae, are microscopic organisms that naturally occur in lakes, streams, and ponds.

Rapid and expansive growth of cyanobacteria is referred to as a “bloom,” according to the Illinois EPA.

An example of blue-green algae blooms in an Illinois lake. | Photo Provided by Illinois EPA.

A sample was collected from Lake Catherine on June 2 and sent to the Illinois EPA for analysis, Young said.

The Illinois EPA notified the health department on Wednesday with final results showing 378 ug/L microcystin toxin. The Illinois EPA’s recommended value is 8 ug/L.

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Young said that it is recommended to avoid contact with water when the following conditions are present:

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

It is recommended to not swim in areas where the blooms are found, minimize contact with the lake water, and not let pets play or drink from the water.

Skin irritation is the most commonly reported side effect of exposure to algal toxins.

Other symptoms range from diarrhea, cramps, vomiting, fainting, numbness, dizziness and tingling. The most severe reactions occur when large amounts of water are swallowed.