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No Further Detection of Anatoxin from Algae in Blue Lakes

Lake County, CA (January 22, 2020) – Follow-up testing after the detection of anatoxin in Blue Lakes in December (detailed in a press release dated 12/18/19) has been negative, so all caution signs have been removed and any restrictions have been lifted.  Initial testing in December demonstrated a low level of anatoxin (0.17 µg/l) and ‘Caution’ signs were posted.  Further tests were conducted on December 16 and January 7, and both specimens showed no signs of toxin.  Per the state’s protocol, when two consecutive tests come back negative, warning signs can be removed and usual activity can be resumed.  Conditions can change at any time, so we recommend continuing to watch for algae blooms, avoid contact, and report changes to Water Resources (707-263-2344) or to Environmental Health (707-263-1090).

The Clear Lake cyanobacteria monitoring program run by the Big Valley Band of Pomo Indians and Elem Indian Colony funded the analysis. Their program has been routinely collecting a water sample at the Upper Blue Lakes as part of their monitoring program.  Further testing will be performed in order to monitor ongoing risk.  This program has been highly beneficial to the health of our community.
For more information, the Water Boards posts information about the bloom on the State Water Boards twitter page:

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:

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