New Harmful Cyanobacteria Bloom (HCB) Recreational Use Advisory

Wyoming Department of Environmental Quality  | view as a webpage

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New Harmful Cyanobacteria Bloom (HCB) Recreational Use Advisory

A harmful cyanobacteria bloom (HCB) recreational use BLOOM ADVISORY has been issued for HAWK SPRINGS RESERVOIR

The Wyoming Department of Health (WDH) works cooperatively with the Wyoming Department of Environmental Quality to issue recreational use advisories when cyanobacteria cell densities or cyanotoxin concentrations pose a risk to people engaging in swimming or similar water contact activities in areas where cyanobacteria 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 WyoHCBs.org

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 courtney.tillman@wyo.gov or (307) 777-5522. Questions regarding cyanobacteria sampling can be directed to Rachel Eyres, Recreational Water Quality Coordinator, Wyoming Department of Environmental Quality, at rachel.eyres@wyo.gov or (307) 777-2073.

Current HCB Recreational Use Advisories*

Waterbody Name

Observation or Sampling Location(s)    

Advisory Type  

Date Issued

Beck Lake

Dog Park

Bloom

7/9/2026

Bighorn Reservoir

Horseshoe Bend Beach

Bloom

7/9/2026

Big Sandy Reservoir

Southeast Shore

Bloom

7/17/2026

Boysen Reservoir

Tamarask Campground

Bloom

7/13/2026

Brooks Lake

Outlet

Bloom

7/21/2026

Glendo Reservoir

Custer Cove Campground

Bloom

7/16/2026

Grayrocks Reservoir

Central East Boat Ramp

Bloom

7/2/2026

Guernsey Reservoir  

Black Canyon Cove Campground

Bloom

6/19/2026

Hawk Springs Reservoir

Northwest Ramp

Bloom

8/6/2026

High Savery Reservoir        

Shore

Bloom

7/2/2026

Lake DeSmet

Mikesell-Potts Recreation Area

Bloom

7/15/2026

Little Soda Lake

Shore

Bloom

7/13/2026

McKenzie Lake

Dog Park Shore

Bloom

7/16/2026

Miller Lake

Shore

Bloom

7/31/2026

Pathfinder Reservoir

Bishops Point

Bloom

7/16/2026

Saratoga Lake

West Central Beach

Bloom

7/28/2026

Sloans Lake

South Beach

Bloom

8/4/2026

South Worland Pond

Shore

Bloom

5/26/2026

V Lake

Shore

Bloom

7/31/2026

Wheatland Reservoir #1

Southwest Ramp

Bloom

7/16/2026

Wind River Lake

Shore

Bloom

7/30/2026

*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.