What is Blue-Green Algae?

Blue-green algae, also known as cyanobacteria, is a bacteria that clusters in colonies, and not an algae or any plant at all. It is quite common in lakes with too many nutrients, particularly in shallow areas that are warm and still.

Cyanobacteria appear in blooms, usually in still coves, on the surface or just under the surface.

Characteristics of blooms include:

• 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.

Are Cyanobacteria Blooms Dangerous?

They can be. When cyanobacteria die, they sometimes release toxins. Toxins can be swallowed, absorbed through the skin, or breathed if the bloom has been disturbed into the air. Pets such as dogs are also susceptible.

Here is a list of symptoms, pulled directly from the US EPA:

It is extremely difficult to determine how dangerous any bloom is. A highly visible bloom may not produce any toxins, and a barely visible bloom may produce high amounts of toxins. Monitoring the toxins themselves with testing is the only way to be sure, but testing is not widely available. The Safety Committee is researching the feasibility of a monitoring program. For now, the Safety Committee is reporting blooms to the Illinois EPA, which can sometimes choose to test the water.

If you are concerned you or a pet have symptoms that are a result of exposure to algal toxins, contact your health care provider or call the Illinois Poison Center at 1-800-222-1222.

How Can I stay safe?

• Do not swim in or swallow water near a visible bloom, or allow pets to swim/drink. Avoid water that has had visible blooms for several days after the bloom disappears, and preferably longer.
• The deeper water in the middle of the lake can usually be considered to be safer.
• When there are any cyanobacteria bloom situations in the lake, shower immediately after lake activities.
• Report any blooms and symptoms to the Safety Committee.

How Can I Help to Prevent Future Blooms?

• Do not fertilize your lawn.
• If you fertilize your lawn, do not use phosphorus, and fertilize at least 15 feet from the lake or areas draining into the lake.
• Upcoming infrastructure projects should improve the water quality and decrease the blooms.

Would you like to know more?

Here are some helpful links:

• US EPA Harmful Algal Blooms
• Illinois EPA Harmful Algal Blooms
• Contact the Safety Committee