23 Clear Lake Sites Tested, Cyanobacteria Concern in 3 Lower Arm Areas and 1 Oaks Arm Area
Lake County, CA (August 12, 2019)– Large, biologically rich natural bodies of water, like Clear Lake, are dynamic in water quality. Understanding what signs to look for when recreating can help ensure residents and visitors safely enjoy our County’s defining feature. Activities such as swimming can greatly enhance well-being, and water monitoring data is one factor that helps all of us make healthy water-based recreation choices.
Water monitoring is regularly conducted by the Big Valley Band of Pomo Indians and Elem Indian Colony. The most recent results reflect testing largely conducted on August 5th, and four areas of Clear Lake demonstrated concerning levels of cyanotoxins, which are produced by blue-green algae.
Testing results from 7/26/19, 8/5/19 - (“danger” level triggering warnings at 20 micrograms per liter µg/L):
Lily Cove/LC01 with a lab result from 7/26/19 of 150 µg/L - Danger Zone (Red)**;
Austin Park Beach/AP01 had a lab result of 48 µg/L on 7/22/19; decreased to 1.9 µg/L on 8/5/19-Caution Zone (Yellow);
Sulphur Bank Mine/SBMMEL01 with a lab result from 8/5/19 of 0.92 µg/L- Caution Zone (Yellow);
Cache Creek Shady Acres/SHADY01 had a lab result of 25 µg/L on 7/26/19; decreased to 0.87 µg/L on 8/5/19 – Caution Zone (Yellow)*;
Redbud Park/RED01 had a lab result of 32 µg/L on 7/26/19; decreased to 0.41 µg/L on 8/5/19 –Below Caution Zone*;
* Lab results improved from Danger to Caution or below Caution level from additional testing done in between sampling events (7/26/19 compared to 8/5/19 results)
** This site is not yet a regular sampling site; however Danger Level from preliminary Abraxis strip testing done on 7/26/19 was confirmed with a lab result
CURRENT RESULTS - 2019 SAMPLING RESULTS/LOCATIONS (See Map Below)
GREEN MARKERS - BELOW CALIFORNIA TRIGGER LEVELS
BLUE MARKERS - REGULAR SITES NOT SAMPLED DURING THIS LAST SAMPLING EVENT
YELLOW MARKERS - CAUTION TRIGGER LEVEL
ORANGE MARKERS - WARNING TRIGGER LEVEL
RED MARKERS - DANGER TRIGGER LEVEL
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 Lower Arm and Oaks 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.
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: