Lake County News, CA – Regarding Cyanobacteria Levels Detected at Lake Pillsbury

Images of microscopic samples taken from Pillsbury Lake on June 20, 2022, courtesy of the Big Valley Band of Pomo Indians.

LAKE COUNTY, Calif. — County health officials report that recent tests have revealed levels of cyanobacteria in Lake Pillsbury.

Cyanobacteria, also known as blue-green algae, are microscopic organisms that occur naturally in all freshwater and marine aquatic ecosystems.

Cyanobacteria or blue-green algae should not be confused with green algae (i.e. phytoplankton), which are beneficial, non-toxic and always present in Pillsbury Lake.

Regional health and water resources officials are reminding those enjoying local lakes and streams to stay aware of cyanobacterial blooms and take appropriate precautions.

As with all large biologically rich bodies of water, Lake Pillsbury is dynamic in terms of water quality.

Recently, during a pre-holiday assessment, water quality technicians observed cyanobacteria in the water column throughout the area, appearing as small grass clippings, strings and clumps .

Pre-holiday samples collected at Lake Pillsbury on June 20 were recently analyzed.

Moderate to low densities of the following genera of cyanobacteria have been identified by microscopy: Aphanizomenon, Woronichinia, and Dolichospermum. The following cyanotoxins were not detected: anatoxin-a, cylindrospermopsin, microcystin and saxitoxin.

Blooms can appear, dissipate or move quickly depending on the conditions of the water body. Updated water quality sampling results will be available next week after the July 4 holiday.

Usually the levels of cyanobacteria are low and not harmful to humans and animals. However, under certain conditions (high nutrients and hot weather), these organisms can grow rapidly, forming visible colonies or “harmful algal blooms”.

The toxic chemicals sometimes produced by these algal blooms are called “cyanotoxins.” Exposure to these toxins causes disease and other serious health effects
people, pets and livestock.

Sensitive individuals, including young children, the elderly, and people with weakened immune systems are most at risk for adverse health effects from cyanotoxins.

Individuals are most often exposed while swimming or participating in other recreational activities in and on water.

The most common routes of exposure are direct skin contact, accidental ingestion of contaminated water, and accidental inhalation of airborne water droplets (eg, while waterskiing).

Symptoms of cyanotoxin exposure include skin rashes, hives, diarrhea, vomiting, coughing, or wheezing. More severe symptoms may result from longer or greater exposure.

Those planning to recreate in or on Lake County waters should look for information signs posted throughout the county and avoid contact with water that:

• looks like spilled green or blue-green paint;
• has scum, mats or films on the surface;
• has a blue or green crust on the shore;
• is discolored or has green streaks; Where
• has greenish globules suspended in the water below the surface.

If you are concerned that you may have symptoms resulting from exposure to cyanotoxins, contact your health care provider immediately or call Lake County Health Services at 707-263-1090. Be sure to report the timing and details of the exhibit.

If you see or think you see a cyanotoxin bloom, please contact Water Resources at 707-263-2344 or Environmental Health at 707-263-1164.

Anyone can report a cyanotoxin bloom or receive additional information at the California Harmful Algal Blooms portal here:

Keep pets and livestock out of the water during harmful algae blooms. Do not let pets and livestock drink the water or allow them to lick their fur after swimming in water containing cyanobacteria. If you or your pet comes in contact with water that you suspect has a cyanotoxin bloom, flush with clean, cool water as soon as possible.

If your pet has any symptoms that may be the result of exposure, contact your veterinarian immediately and let them know the timing and details of the exposure.

To find the most up-to-date information on Lake County water quality and where cyanotoxin blooms have been identified, visit the Big Valley Band of Pomo Indians Cyanotoxin Monitoring webpage here: www.bvrancheria. com/clearlakecyanotoxins.

For more information on cyanobacteria and harmful algal blooms, please visit the following sites:

• Centers for Disease Control and Prevention (CDC):
• Environmental Protection Agency (EPA):
• Lake Cyanobacteria County web page:


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