Bacterial blooms persist into fall, officials recommend caution

The Wyoming Department of Environmental Quality is warning residents that harmful cyanobacterial blooms will persist in some lakes and reservoirs into the fall.

Although most blooms occur during the warmer months and blooms typically dissipate as temperatures decrease, some of the single-celled organisms persist into the fall and winter seasons and pose health risks to humans and can also be fatal to wildlife, domestic pets and livestock.

Exposure can result in rashes, itching, numbness, fatigue, disorientation, abdominal pain, vomiting and diarrhea.

The highest risk area is Boysen Reservoir, where blooms are reported at the marina and most of the reservoir's boat ramps and camp groups. Blooms are also confirmed at Keyhole Reservoir, the dog park shore at Lake McKenzie in Casper, the south access area of Leazenby Lake and the North Red Hills ramp at Seminoe Reservoir.

DEQ and the Department of Health are recommending:

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, 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.

Zakary Sonntag is an Energy & Environment reporter for the Star-Tribune. He can be reached at

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