Harmful algal blooms confirmed at Lake Crowley; public urged to avoid water activities

SACRAMENTO – Tests have confirmed harmful algal blooms (HABs) at multiple locations in Mono County’s Lake Crowley, prompting the Lahontan Regional Water Quality Control Board to urge people and pets to stay out of the water.

The Lahontan Regional Water Board has a recreational “danger” advisory at two locations, the Marina and Hilton Creek Drainage, to alert lake users of the elevated risk. Until the advisories are lifted, people visiting the lake should mind the following HAB guidance:

Danger

  • Stay out of the water until further notice, including watercraft.
  • Do not let pets and other animals drink or go into the water or go near the scum.
  • Stay away from scum, and cloudy or discolored water.
  • Do not eat fish or shellfish from this water.
  • Do not use this water for drinking or cooking. Boiling or filtering will not make the water safe.

Lahontan Regional Water Board staff monitored Crowley Lake on Sept. 24 and noticed visual signs of HABs near the South Landing area of the lake at both the Marina and the Hilton Creek Drainage. Sample results confirmed that toxin levels were present at dangerous levels at both locations.

Cyanobacteria, a group of organisms that form HABs, can produce potent toxins. Health risks are associated with HABs, as they produce dermatoxins that can cause itching skin and rashes, as well as gastrointestinal distress, headaches, agitation and weakness, or abnormal breathing if HAB material is swallowed while swimming. Dogs and children are most susceptible to exposure because of their smaller body size, increased potential to swallow water while swimming and tendency to stay in the water longer. If you suspect exposure, wash your children and dog immediately.

The bloom occurring in the lake appears suspended on the water’s surface. Bloom

conditions can change rapidly, as the winds and waves move or concentrate the bloom into different regions of the lake. In some areas, the bloom may concentrate and form a film or scum on the water surface. The color of the water may also appear discolored as bright or dark green and brown.

The California Water Boards will provide regular updates to inform the community when postings are removed on the California HAB Reports Web Map.

The Water Boards recommend that people practice healthy water habits while enjoying the outdoors at your local lake, river or stream:

  • Heed all instructions on posted advisories if present.
  • Avoid algae and scum in the water and on the shore.
  • Keep an eye on children and pets.
  • If you think a harmful algal bloom or toxic algal mats are present, do not let pets and other animals go into or drink the water or eat scum/algal mats on the shore.
  • Don’t drink the water or use it for cooking.
  • Wash yourself, your family and your pets with clean water after water play.
  • If you catch fish, throw away guts and clean fillets with tap water or bottled water before cooking.
  • Avoid eating shellfish if you think a harmful algal bloom is present.

Get medical treatment immediately if you think that you, your pet, or livestock has gotten sick after going in the water. Be sure to alert the medical professional to the possible contact with cyanobacteria. Also, make sure to contact the local county public health department.

To report a bloom, do one of the following:

For more information about HABs, please visit the California Harmful Algal Blooms Portal.