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Potential for Human Illness Associated with Blue-Green Algae Blooms in Oklahoma lakes

Blue-green algae (BGA), also known as cyanobacteria, are microscopic organisms that live in water.  The algae are usually too small to be seen, but sometimes can form visible algae blooms.  BGA blooms can form in warm, slow-moving waters that are rich in nutrients.  Blooms usually occur in late summer or early fall.  BGA can produce toxins that may contaminate drinking or recreational water, and can produce toxins (anatoxin, microcystins, etc.) that can cause illness in humans and animals.

BGA can be found in any body of water, such as, lakes, ponds, creeks, ocean, and brackish water.  BGA blooms can look like foam, scum, or mats on the surface of water.  The blooms can be blue, bright green, brown, or red.  Some blooms may not affect the appearance of the water.  As algae in the BGA blooms die, the water may have an unpleasant odor.

Potential health effects can vary and are dependent upon the type of toxin present and the route of exposure.  Contact with high concentrations of cyanobacteria, independent of the level of toxins, may also cause adverse health effects.

Exposure to BGA may cause the following symptoms:

  1. Skin Exposure: rash, hives, or skin blisters.
  2. Inhalation: runny eyes, runny nose, sore throat, asthma like symptoms, or allergic reactions
  3. Ingestion: Acute, severe gastroenteritis (stomach cramps, nausea, diarrhea or vomiting)

The time period between exposure to BGA and developing symptoms is unknown.  However, it may take hours or days for liver toxicity to show up in humans or animals, and neurotoxicity symptoms may appear within 15 to 20 minutes after exposure.  There are currently no tests to detect cyanobacteria toxins or antibodies in human specimens.  Medical care is supportive.

The Oklahoma State Department of Health (OSDH) recommends individuals to avoid swimming or participating in water recreational activities where the water is discolored or where you see foam, scum, or mats of algae on the water.  Individuals are also advised to follow any water body closures announced by the DEQ or GRDA. 

Please contact the DEQ Complaint Hotline (24/7/365) at 1-800-522-0206 for questions regarding blue-green algal blooms or visit the DEQ website at  Individuals experiencing symptoms after exposure to affected lakes may contact the OSDH Acute Disease Service at 1-800-234-5963 to report their illness.

Agencies that monitor Oklahoma lake water quality

Check Oklahoma Lake Conditions (Oklahoma Department of Tourism)

US Army Corps of Engineers – Tulsa District

Blue-Green Algae Fact Sheets and Information

Blue-Green Algae Fact Sheet, Oklahoma State Dept. of Health (OSDH)

Blue-Green Algae Fact Sheet, Oklahoma Department of Environmental Quality (OK DEQ) 

Harmful Algal Blooms, Centers for Disease Control and Prevention (CDC)

Facts about Blue-green Algae, Wisconsin Department of Health Services