The Alpine County Health Department has been working with The Lahontan Regional Water Quality
Control Board and South Tahoe Public Utility District and the Alpine Watershed Group (AWG) in
determining that there are levels of toxin associated with blooms of blue-green algae in multiple lakes
in Alpine County that are toxic to animals and humans.
Samples have been collected from Red Lake and Heenan Reservoir which have shown no toxins are
present at this time requiring no advisories.
Levels at Indian Creek Reservoir have been determined to be well above the “DANGER” level.
The lake is being posted with the appropriate warning signs in effect until further notice. Ongoing testing
will be conducted on a regular basis. My prediction (always risky but based on evidence!) is that
conditions will get worse before they get better. My hypothesis is that significant amounts of ash from
the Tamarack Fire surrounding the lake have been washed into the lake with each rain event this
winter and spring creating a nutrient rich environment facilitating growth of the algae.
Potential symptoms in dogs following exposure to blue-green algae toxins can include lethargy,
difficulty breathing, salivation, vomiting, urination, diarrhea, or convulsions leading to death.
The unexplained death of a dog after contact with contaminated water is often a sentinel event which
alerts officials to the potential of a toxic bloom. People can experience eye irritation, skin rash, mouth
ulcers, vomiting, diarrhea, and cold or flu-like symptoms, with impacts to the liver. Dogs and children
are most likely to be affected because of their smaller body size and tendency to stay in the water for
longer periods. While there is no antidote for exposures, persons should see their physician and
those with pets which may have been exposed should go to their veterinarian for supportive care.
Livestock who are drinking contaminated water can also suffer fatal consequences.
Blue-green algae (known as cyanobacteria) can be naturally present in any body of fresh water. It
looks like green, blue-green, white or brown scum, foam or mats floating on the water. Warmer air
and water temperatures, high nutrient levels, and slow and stagnant water can cause cyanobacteria
to multiply at an excessive rate and turn in to a harmful algae bloom (HAB). When HABs are present,
the algal scum can be a variety of colors such as fluorescent blue, green white, red or brown. Blooms
can have more than one color present and may look like thick paint floating on the water and give off
a foul odor. HABs may move to different locations of the lake by wind or wave. If you see signs of a
HAB, such as discolored, pea-green water, surface scum, floating algae, stay out of the water.
A few good links:
State Incident Report Map, where you can see updates on blooms across the State
Healthy Water Habits page on the CA HABs Portal.
The State Water Board and the nine Regional Water Boards (known as the Water Boards), in
partnership with other programs and agencies, are actively supporting and coordinating a statewide
HAB incident response with many publicly available resources. To learn how to stay safe around
HABs, report a bloom and more, visit the CA HABs Portal: http://www.mywaterquality.ca.gov/habs/
FAQ: Algae Blooms
What are cyanobacteria and how do they occur?
- Cyanobacteria are small microbes or bacteria that live in nearly every habitat on land and in the water. They have existed for billions of years as essential components of freshwater ecosystems and form the foundation of most aquatic food chains.
- When environmental conditions favor the growth of cyanobacteria and algae – warm temperatures and low or stagnant water flows, excessive nutrient inputs they can multiply very rapidly creating nuisance blooms.
- Some cyanobacteria are capable of producing toxins that can harm pets or
people that come into contact with them.
- Not all cyanobacteria produce toxins, but those that do can cause
rashes, diarrheal disease and respiratory problems.
- Different genera of cyanobacteria can produce different toxins that pose
a health risk if ingested. Children and dogs are particularly vulnerable,
but adults can also experience eye irritation, allergic skin rash, mouth
ulcers, vomiting, diarrhea, and cold and flu-like symptoms. Ongoing
daily exposures can lead to more serious effects.
- In California, harmful algal blooms are most common during the warm
weather months between late May through October, but they can occur
Additional Information on HABs:
• HABs can be a variety of colors such as green, white, red or brown. They can
be more than one color and may look like thick paint floating on the water.
Blooms can also appear as algal mats in rivers and streams, and also shallow
areas of lakes.
○ In lakes, they usually are a mix of intense shades of green paint-like
sheen on the water’s surface.
○ In rivers, the look like algal mats that are attached to the bottom of the
river. The algal mats can also become stranded on a shoreline. floating
mats of algae-like material.
Factors contributing to blooms?
• Common factors contributing to blooms are warm weather, sunlight, large rain
events and nutrient run-off.
• Current research suggests that climate change provides a catalyst for their
○ Rising temperatures and changing precipitation patterns both energize
○ Warmer temperatures can favor blooms because many genera of
cyanobacteria are adapted to hot conditions and they grow most at
relatively high temperatures; often in excess of 25 °C where they
generally outcompete eukaryotic algae.
• Rising global temperatures also change weather patterns and amounts of
precipitation, which may support cyanobacteria growth.
○ The frequency of extreme rainfall events is projected to increase.
○ This will lead to larger surface and groundwater nutrient discharge
events into water bodies.
What should you do if you see a bloom?
• Practice Healthy Water Habits:
○ Avoid algae and scum in the water
○ Keep an eye on children and pets (dogs); they are most susceptible for
○ If in doubt, keep pets out! Do not let pets and other animals go into or
drink the water, or eat scum on the shore
○ Do not drink this water or use it for cooking
○ Wash yourself, your family and your pets with CLEAN water after playing
○ If an advisory is posted, follow all instructions on posted advisory
How to report a suspected bloom?
• Please report blooms to the CA HABs Portal using the ‘Report a Bloom’ feature.
○ Reports will alert the CA Water Boards and our sister agencies of the
need for assistance and will expedite our efforts to track the frequency,
distribution and impacts of HABs in California.
Information specific for dog owners
• Dog owners should be aware of HABs just as they are aware of other potential
risks or hazards (such as poison oak, rattlesnakes, mountain lions, and so on)
when outdoors with their dogs.
○ Bring bottled water with you to give to your dog to drink. When in doubt,
stay out. But also don’t be afraid to be outdoors. Enjoy the outdoors and
just be aware.
• If your animal gets in the water with a bloom, immediately wash them with
clean water and do not let them lick their fur.
• If your pet displays symptoms such as seizures, vomiting, or diarrhea after
contact with surface water, contact your veterinarian right away. Animals and
livestock can become very ill and die after exposure to harmful algal blooms.
○ Provide your vet with this fact sheet that assists with identification of
illness due to cyanotoxins.
○ Limited funding is available to cover physical examination of ill dogs
with suspected poisoning, and other lab analyses.
Information on Water Board Freshwater and Estuarine Harmful Algal Bloom
• While cyanobacteria have been around for millions of years, the state’s
program to address HABs is relatively new (within the last couple of years).
○ We are currently working on collecting data to better track the
occurrence and frequency of HABs statewide.
○ Based on the limited data that we do have from voluntary reports, there
was a twofold increase in reported HABs from 2016 to 2017. Most
recently, reports are increasing each year with over 300 in 2020, and
over 600 reports in 2021.
○ Awareness of HABs has likely also increased, so it’s difficult to say with
certainty that things are getting worse; however, we can say with
certainty that HABs can cause adverse health effects in humans and
that animal and livestock can become very ill and/or die after exposure
○ The Water Board FHAB Program also does not have the resources to
investigate every water body across the state or respond to every
incident reported, so it is vital for the public to always follow Healthy
Where should the public go for more information on HABs in California?
• The California Water Quality Monitoring Council HAB web portal:
https://mywaterquality.ca.gov/habs/index.html as it contains a HAB Incident
Report map updated daily on all HAB information received by the Water Board
and resources available for the public (i.e. fact sheets; FAQs; videos).
Planktonic vs. benthic bloom planktonic tend to float/drift near the top of the water
and benthic are attached to a substrate (i.e. rocks) at the bottom of the water
harmful algal bloom vs. harmful algal mats harmful algal bloom is a general term for
any type of toxin producing bloom whereas harmful algal mats are specific to benthic
toxin producing cyanobacteria that can be attached in mats on substrate or dislodged
and floating near shores. Often harmful algal mats refer to harmful algal blooms in
streams or rivers
FHAB Program the Water Board Freshwater and Estuarine Harmful Algal Bloom
Program consisting of 2 staff at the State Water Resources Control Board and 3 staff at
the Regional Water Quality Control Boards (Lahontan; Central Valley; North Coast)
Algae vs. bacteria cyanobacteria are often referred to as an algae but are actually a
bacteria. These terms to describe cyanobacteria are often used interchangeably
HAB “harmful algal bloom” and preferred language when referring to a cyanobacteria
bloom producing toxins; do not use “blue-green algae,” “green algae,” or any other