Blue-Green Algae Detected near Granite Springs Reservoir

The Wyoming Department of Health (WDH) has issued a harmful cyanobacterial bloom recreational use advisory for the Causeway at the City of Cheyenne Board of Public Utilities’ (BOPU) Granite Springs Reservoir.

The reservoir is located about 30 miles west of Cheyenne in Curt Gowdy State Park. The Causeway is an area west of the Granite Springs Reservoir where Middle Crow Creek flows toward the reservoir. The Causeway is separated from the main reservoir by a road.

Harmful cyanobacteria, also known as blue-green algae, can form harmful blooms in slow-moving water during the late summer when water temperatures are warmer. These blooms are considered harmful because they can produce toxins and other irritants that pose a risk to humans, pets, livestock and wildlife.

Cyanobacteria was not detected in the main reservoir, a source for Cheyenne’s drinking water. BOPU laboratory staff will continue to monitor water quality in Cheyenne’s water sources. The BOPU is also working with Curt Gowdy State Park to notify recreational users in the park of affected area.

The BOPU is asking residents to follow these recommendations:

  • 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 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.