The Wyoming Department of Health is urging recreationists to use caution at Brooks Lake in the Shoshone National Forest, after water sampling detected a harmful cyanobacterial bloom (HCB). HCBs — also known as harmful algal blooms — are dense concentrations of cyanobacteria or blue-green algae that pose a health risk to humans, pets, livestock, wildlife and aquatic life.

The advisory at Brooks Lake, located northwest of Dubois, will remain in place until the bloom has fully dissipated and cyanotoxin concentrations are below recreational use thresholds.

Under normal conditions, cyanobacteria are present at low levels and play an important role in aquatic ecosystems. When blooms occur, cyanobacteria become visibly abundant and can look like grass clippings, blue-green scum, or spilled paint on the water surface. HCBs may also be found suspended in the water column and make the water appear green. Cyanobacteria can produce toxins and other irritants that can cause health effects such as rashes, fatigue, disorientation and gastrointestinal illnesses. In extreme cases, toxins may lead to pet, livestock or wildlife death.

Blooms may only be present in certain areas of the waterbody and conditions can change frequently, the Department of Health says. As of Tuesday, there were 15 active advisories in Wyoming, including near the Brannon Boat Ramp at Boysen Reservoir, north of Shoshoni. No water bodies in the Big Horn Basin are on the list.

Recreationists are urged to avoid contact with the water where scum is visible. Other safety tips include: Do not ingest water from the bloom; rinse fish with clean water and eat only the fillet; and 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 and contact a doctor or veterinarian. For more information, visit www.WyoHCBs.org.