Notice to Avoid and Report Possible Harmful Cyanobacterial Blooms in Wyoming Waters

Water Quality Division
Published: June 15, 2020

CHEYENNE, Wyo – With summer nearly upon us and more people heading to Wyoming’s lakes and reservoirs to recreate, the Wyoming Department of Environmental Quality (DEQ), the Wyoming Department of Health (WDH), and the Wyoming Livestock Board (WLB) want to remind the public to avoid and keep animals away from cyanobacterial blooms and to report suspected blooms to DEQ.

Cyanobacteria, also known as blue-green algae, can form harmful cyanobacterial blooms (HCBs) that produce toxins and other irritants that pose a risk to human and animal health. HCBs typically occur when water temperatures increase in still or slow-moving water, or when wind aggregates cyanobacteria near shorelines. HCBs are generally blue or green in color and may appear as green water, small grass clippings, scum, floating mats, or spilled paint on the water surface. HCBs may also be attached to rocks, sediment, or plants at the bottom of a waterbody. When HCBs form, they may last days, weeks or even months. Suspected HCBs can be reported to DEQ by calling 307-777-7501 or submitting a complaint online at WyoSpills.org.

Once reported, DEQ will investigate potential blooms to determine if they are harmful. The Wyoming Department of Health will issue advisories for publicly accessible waters when levels of cyanobacteria and/or toxins pose a risk to people engaging in swimming or similar types of water recreation activities. A map of advisories and answers to frequently asked questions (FAQs) can be found at: WyoHCBs.org.

If a harmful bloom is present, the WDH and WLB recommend the following:

  • Avoid contact with water in the vicinity of the bloom, especially in areas where cyanobacteria are dense and form scum.
  • Do not ingest water from the bloom. Boiling, filtration and/or other treatments will not remove toxins.
  • Rinse fish with clean water and eat only the fillet portion.
  • Avoid water spray from the bloom.
  • Do not allow pets or livestock to drink water near the bloom, eat bloom material or lick fur after contact.
  • If people, pets or livestock come into contact with a bloom, rinse off with clean water as soon as possible.

Seek medical attention or a veterinarian if a person or animal is experiencing adverse health effects after exposure to a cyanobacterial bloom. Young children, pregnant women, people with weak immune systems and animals are especially at risk. Questions regarding general health risks and symptoms related to a cyanobacterial bloom can be referred to Dr. Karl Musgrave, state public health veterinarian and environmental health epidemiologist with WDH at 307-777-5825. Health information is also available at https://www.cdc.gov/habs/.

For more information, visit the DEQ’s Wyoming’s HCB webpage at WyoHCBs.org.

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