Harmful Cyanobacterial Bloom (HCB) Recreational Use Advisory: Lake DeSmet

Wyoming Department of Environmental Quality  | view as a webpage

Wyoming Department of Environmental Quality

Harmful Cyanobacterial Bloom (HCB) Advisory: Lake DeSmet

The Wyoming Department of Health (WDH) has issued a harmful cyanobacterial bloom (HCB) recreational use Bloom Advisory for Lake DeSmet based on data provided by the Wyoming Department of Environmental Quality (DEQ). The WDH is working directly with resource management agencies to ensure that signs are posted at all waterbodies with advisories. Additional details regarding advisory status, including changes to the type of advisory, and other HCB resources can be found at WyoHCBs.org

The WDH issues recreational use advisories when cyanobacterial cell densities or cyanotoxin concentrations pose a risk to people engaging in swimming or similar water contact activities in areas where cyanobacterial blooms occur. HCBs may also pose a health risk to animals. Bloom Advisories are issued when a HCB is present and toxins may be present. Toxin Advisories are issued when cyanotoxins exceed recreational thresholds. Waterbodies under an advisory are not closed since HCBs may only be present in certain areas and conditions can change frequently. Advisories will remain in place until blooms have fully dissipated and cyanotoxin concentrations are below recreational use thresholds identified in Wyoming's HCB Action Plan.

The table below outlines the recreational use advisories that remain in effect. Many blooms have begun to dissipate as temperatures have decreased this fall. DEQ continues to monitor waterbodies this fall and winter and will provide updated information on sampling results and advisory status via the HCB Advisories Webmap.

If you encounter a potential HCB, the Wyoming Department of Health and the Wyoming Livestock Board recommend the following:

  • Avoid contact with water in the vicinity of the bloom, especially in areas where cyanobacteria are dense and form scums.
  • 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 and contact a doctor or veterinarian.


Questions about health effects and recreational use advisories can be directed to Courtney Tillman, Surveillance Epidemiologist, Wyoming Department of Health, at courtney.tillman@wyo.gov or (307) 777-5522. Questions regarding cyanobacteria sampling can be directed to Kelsee Hurshman, Natural Resource Analyst, Wyoming Department of Environmental Quality, at kelsee.hurshman1@wyo.gov or (307) 777-2073.

Current HCB Recreational Use Advisories

Waterbody Name Observation or Sampling Location(s)    Advisory Type   Date Issued
Big Sandy Reservoir West Shore, Dam Area Bloom 7/28/2021
Boysen Reservoir Swim Beach, Tough Creek Camp Toxin 9/28/2021
Brooks Lake Boat Ramp Bloom 8/31/2021
Buffalo Bill Reservoir Bartlett Lane Bloom 8/19/2021
Diamond Lake (Bosler Reservoir) Northwest Access Toxin 10/14/2021
Eden Reservoir South Outlet Bloom 7/28/2021
Flaming Gorge Reservoir  Buckboard Marina, Firehole Beach Bloom 7/29/2021
Fontenelle Reservoir West-Central Boat Ramp Bloom 8/19/2021
West Granite Springs  West Causeway Bloom 7/29/2021
Kemmerer City Reservoir East Access Bloom 9/13/2021
Keyhole Reservoir Wind Creek Toxin 9/3/2021
Lake DeSmet North Dam Bloom 12/6/2021
Ocean Lake Long Point, South Cove Toxin 9/28/2021
Pelham Lake East Shore Bloom 8/31/2021
Rainbow Lake East Shore Bloom 8/31/2021
Saratoga Lake West Boat Ramp, West Beach Toxin 8/25/2021
Upper Brooks Lake East Shore Bloom 10/4/2021
Upper Jade Lake South Shore Bloom 8/31/2021
Viva Naughton Reservoir East Ramp Bloom 8/19/2021
Woodruff Narrows North Boat Ramp Toxin 9/13/2021