Harmful algal bloom found at Indian Creek Reservoir

Submitted to the Tribune

SOUTH LAKE TAHOE, Calif. – The Lahontan Regional Water Quality Control Board is urging visitors to Indian Creek Reservoir in Alpine County to stay out of the water after tests confirmed the presence of harmful algal blooms that can pose a health threat to humans and their pets. A lakewide “DANGER” advisory has been posted to alert lake users of the elevated risk.

Visitors to the reservoir are encouraged to follow the below guidance until further notice. 


  • Stay out of the water, 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.

Indian Creek Reservoir is routinely monitored by South Tahoe Public Utility District. During testing on Aug. 22, staff observed a harmful algal bloom with a spilled paint appearance. Monitoring results confirmed toxins are present at a danger level threshold at all three of the areas monitored. The advisory has been issued for the entire lake.  

Note that cyanobacteria, a group of organisms that form harmful algal blooms, can produce potent toxins. Health risks are associated with HABs as they produce dermatoxins that can cause skin inflammation, which 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. Due to the size and toxicity of the bloom with increasing temperatures and decreased precipitation this time of year, the bloom may proliferate and alter its potential to produce toxins. 

Algal bloom danger sign

 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. 

 Advisory signs to notify recreational users of the bloom have been posted. The Water Board will provide regular updates to inform the community when postings are removed on the California HAB Reports Web Map.

The Water Board recommend that people practice healthy water habits while enjoying the outdoors this summer 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:
  • Call the HABs hotline: 1-844-729-6466 (toll free)
  • Contact your County Public Health Office

Support Local Journalism

Support Local Journalism

Readers around the Lake Tahoe Basin and beyond make the Tahoe Tribune's work possible. Your financial contribution supports our efforts to deliver quality, locally relevant journalism.

Now more than ever, your support is critical to help us keep our community informed about the evolving coronavirus pandemic and the impact it is having locally. Every contribution, however large or small, will make a difference.

Your donation will help us continue to cover COVID-19 and our other vital local news.