Blue-green Algae

• Many of Ohio's lakes and streams contain cyanobacteria, often known as blue-green algae. It is caused when conditions such as fertilizer runoff from nearby farms create algal blooms. Some of those blooms can become harmful algal blooms, also known as HABs, that can cause neurotoxins and hepatoxins.
  
  

How It Forms

• According to the Ohio Department of Natural Resources, blue-green algae are more prevalent in the summer months, when hotter weather and more sunlight can cause the algal blooms to grow larger and more rapidly. Scientists have not yet figured out why some blooms produce toxins while others do not.
  
  

Grand Lake St. Marys

• While many of Ohio's lakes have been contaminated with blue-green algae, the one that has received the most attention is Grand Lake St. Marys, Ohio's largest inland lake. A popular spot for recreation, the lake has become contaminated with harmful algal blooms as the water quality in the lake has declined. Ohio agencies have spent thousands of dollars to treat the lake to kill the algae and have been working with surrounding communities to limit the runoff of nutrients into the water that cause the blooms.
  
  

Health Problems

• A number of health problems can be caused by exposure to harmful algal blooms. If it comes into contact with your skin, the Ohio Department of Health warns that it can cause rashes, hives or skin blisters. If you breathe water droplets, you can suffer runny eyes and noses, a sore throat, asthmalike symptoms or allergic reactions. Swallowing water contaminated with toxic blooms may cause severe diarrhea and vomiting, and toxicity in your liver, kidneys or nervous system.
  
  

Other Problems

• In addition to the health problems, a harmful algal bloom can create odors in drinking water and reduce oxygen levels for fish. Scums may also pollute lake beaches.
  
  

Avoiding Algal Blooms

• Many of the public lakes in Ohio post warnings when a lake is contaminated with the algal blooms. In addition, the Ohio Sea Grant College Program recommends that you avoid contact with water that is pea-green, has a floating bright green scum or is generally discolored. You should also avoid drinking lake or river water and keep your family members and pets from doing the same.