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29 Clear Lake Sites Tested For Cyanobacteria, “Elevated” Levels of Cyanotoxin Near Austin Park

Lake County, CA (June 10, 2020) – Clear Lake is finally open now, and summer is rapidly approaching.  Due to the restrictions of recent Shelter-in-Place and statewide Stay at Home Orders in response to COVID-19, people have been especially excited to use the lake this year. 

Water-based activities can be a great enhancement of overall well-being, and must be done safely.  Social distancing and other precautions must augment awareness of the risks customarily associated with large, biologically rich natural bodies of water.

Like all natural bodies of water, Clear Lake is dynamic in water quality.  Understanding the signs to look for when recreating can help ensure residents and visitors safely enjoy our County’s defining feature. 

Water monitoring data is one factor that helps all of us make healthy water-based recreation choices.  We are very fortunate that lake water monitoring is regularly conducted by the Big Valley Band of Pomo Indians and Elem Indian Colony at approximately 30 Clear Lake sites.

Testing conducted on June 8 showed one area of Clear Lake with concerning levels of cyanotoxins, which are produced by blue-green algae (also known as cyanobacteria).

Significant Testing result from 6/8/2020:

Austin Park Beach/AP01 had a screening Abraxis test strip showing more than 20 parts/billion of microcystin cyanotoxin.  This is considered “elevated,” and raises concern, and the samples were sent to a regional lab for confirmation and quantification.  Caution signs have been posted.

In the same area, there has been visual evidence of large algal blooms that resemble the kinds that produce cyanotoxins.  Additionally, last week, one person reported a skin reaction after boating through a large bloom in the area.

28 other sites around the lake were tested, and did not show elevated levels on the screening tests performed.

Public Health urges boaters and recreational users to avoid direct contact with or use of waters containing cyanobacteria in Lake County.  The recommendation is based on the potential health risks from cyanobacteria, which is currently blooming at varying levels in the Clearlake Oaks area and the Lower Arm of Clear Lake.

Cyanobacteria can pose health risks, particularly to children and pets. We urge people to choose safe activities when visiting natural bodies of water, particularly where blooms are visible.  It is strongly recommended that people and their pets avoid contact with water and avoid swallowing lake water in an algae bloom area.

If anyone you are with begins to experience problems (skin, gastrointestinal, neurologic) that may be related to contact with blue- green algae (cyanobacteria), contact your medical provider or go to the Emergency Department.  If your animal has symptoms, contact your veterinarian immediately. 

In either circumstance, call the Public Health Department, at 707-263-1164, so further investigation can be undertaken.

For current cyanotoxin lab results, please visit the Big Valley Band of Pomo Indians cyanotoxin monitoring website:

For more information and resources, visit the County’s cyanobacteria pages:

For general Water Quality questions regarding Clear Lake, call Lake County Water Resources, at 707-263-2344.

Thank you for taking appropriate precautions.

Gary Pace, MD, MPH

Many thanks to the Big Valley Band of Pomo Indians, Elem Indian Colony, and the Lake County Water Resources Department for their invaluable contributions to this release.

Cyano Austin Park

Austin Park 6/8/20

Soda Bay June 2020
Soda Bay Cove 6/27/16

Soda Bay Cove June 2017
Soda Bay Cove 7/31/17

Cayno June 2020Gloeotrichia (large one) and Microcystis (smaller ones) August 6, 2019 at Austin Park

Cyao June 2020Gloeotrichia (spiked) and Microcystis (smaller ones) June 6, 2020 at Austin Park

Cyano Rods
Dolichospermum at Rodman Slough July 21, 2017

Microcystin June 2020
Microcystis at Lakeshore Drive (Lakeport) August 20, 2019

Water Faucet
Urgent Health Advisory

Effective immediately, people on private water systems whose tap water comes from their own private intake into the lake, in the Oaks Arm and Lower Arm of Clear Lake should not drink the water.

More info