Harmful algal bloom confirmed at Bridgeport Reservoir; public urged to avoid water activities.

MONO COUNTY –Tests have confirmed harmful algal blooms at multiple locations in Mono County’s Bridgeport Reservoir, 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 posted a recreational “warning” advisory for the Old Marina Boat Ramp area and a “danger” advisory for areas near the dam and RV park to alert lake users of the elevated health risk. Until the advisories are lifted, people visiting the popular boating and fishing lake located approximately 25 miles north of Mono Lake should mind the following harmful algal blooms (HABs) guidance:

Warning (Old Marina Boat Ramp)

  • No swimming.
  • Do not let pets and other animals go into or drink the water, or eat scum on the shore.
  • Stay away from scum, and cloudy or discolored water.
  • Do not use this water for drinking or cooking. Boiling or filtering will not make the water safe.
  • For fish caught here, throw away guts and clean fillets with tap water or bottled water before cooking.

Danger (RV Park and Dam)

  • 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 from this water.
  • Do not use this water for drinking or cooking. Boiling or filtering will not make the water safe.

Walker River Irrigation District, a regional partner that assists with HABs monitoring, noticed a potential bloom at Bridgeport Reservoir during a post-Labor Day assessment. Results from samples taken Sept. 23 at Old Marina Boat Ramp, the RV park and dam areas confirmed toxins were present at levels that exceed the warning and danger level thresholds. The blooms remain visible and appear to be extensive, so please steer clear of any visual signs of the bloom.

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 Bridgeport Reservoir 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.

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:

Fill out the Bloom Report form on the HABs Portal.

Email CyanoHAB.reports@waterboards.ca.gov.

Call the HABs hotline: 1-844-729-6466 (toll free).

Contact your County Public Health Office.

For more information about HABs, please visit the California Harmful Algal Blooms Portal and the California Department of Public Health Resource Page.