Harmful cyanobacterial bloom toxin advisory issued for Boysen Reservoir, Ocean Lake

    (Fremont County, WY) – A harmful cyanobacterial bloom (HCB) recreational use Toxin Advisory has been issued for Boysen Reservoir and Ocean Lake, according to a release issued by the Wyoming Department of Environmental Quality on August 24.

    The Wyoming Department of Health (WDH) works cooperatively with the Wyoming Department of Environmental Quality to issue 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.

    The WDH is working directly with resource management agencies to ensure signs are posted at the reservoir. Additional details regarding advisories and other HCB resources can be found at


    Bloom advisories are issued when a HCB is present and cyanotoxins 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. 

    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 [email protected] or (307) 777-5522. Questions regarding cyanobacteria sampling can be directed to Kelsee Hurshman, Natural Resource Analyst, Wyoming Department of Environmental Quality, at [email protected] or (307) 777-2073.


    Current HCB Recreational Use Advisories*

    Waterbody Name     Observation or Sampling Location(s)   Advisory Type  Date Issued
    Beck LakeEast RampBloom08/03/2023
    Boysen ReservoirBrannon Ramp, Cottonwood BayToxin08/24/2023
    Brooks LakeSouth RampBloom08/03/2023
    Buffalo Bill ReservoirBartlett BeachBloom08/18/2023
    Festo LakeEast ShoreBloom07/13/2023
    Flaming Gorge ReservoirFirehole BeachBloom07/19/2023
    Gillette Fishing LakeEast Dam, North ShoreBloom08/18/2023
    Glendo ReservoirCuster Cove, Cottonwood CampgroundBloom08/09/2023
    Goshen Hole ReservoirNorthwest CampgroundBloom07/29/2023
    West Granite Springs ReservoirWest CausewayBloom08/09/2023
    High Savery ReservoirDamBloom07/12/2023
    Lake Viva NaughtonEast ShoreBloom07/19/2023
    Kemmerer City ReservoirEast AccessBloom08/18/2023
    Leazenby LakeSouth AccessToxin08/03/2023
    Miller LakeNortheast ShoreBloom 08/01/2023
    Ocean LakeLong PointToxin08/24/2023
    Pathfinder ReservoirBishops PointToxin08/10/2023
    Saratoga LakeWest-Central ShoreToxin08/10/2023
    Seminoe ReservoirSunshine BeachToxin08/10/2023
    Sloans LakeSouth BeachBloom08/14/2023
    Sodergreen LakeSoutheast AccessBloom08/09/2023
    Twin Buttes LakeSouth-Central RampBloom08/09/2023
    Wheatland Reservoir Number 3Northwest CausewayToxin08/03/2023
    Woodruff Narrows ReservoirNorth RampBloom08/04/2023

    *There may be additional waterbodies with HCBs that WDH and WDEQ are not aware of. Please report potential blooms to WDEQ and HCB-related illnesses to WDH.


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