In the Klamath Basin blue-green algae blooms typically occur between June and October when temperatures rise and water conditions are favorable for algal growth. Blue-green algae monitoring typically occurs May - November. If river conditions exceed public health standards for toxic algae the area is posted with a health advisory sign.

BGA Tracker 20211112

View the Klamath BGA Tracker Interactive Map


For more information, please check California's HAB Incident Reports Map.


To get email updates about posting/deposting decisions and other notifications, email This email address is being protected from spambots. You need JavaScript enabled to view it. to join the Klamath Blue Green Algae Workgroup list serve.


Updated Posting Status

Below Threshold 12/18/23- All reservoirs and reaches of the Klamath River are below public health thresholds for cyanotoxins.   


About the Tracker

The BGA Tracker Map was built to inform the public and research community regarding river conditions. The Tracker utilizes current information to track  and map the blue-green algae blooms throughout the Klamath Basin. The Blue-Green Algae Tracker identifies blue-green algae public health threats  (i.e. exceeds health thresholds identified in the appropriate guidance) by river reaches bounded by public health monitoring locations.

River reaches which exceed applicable criteria for public health are indicated by different colors on the map that vary depending on the number of tiers within each jurisdiction's advisory thresholds. Advisory colors within the map are:                 



Yurok Tribe   Yurok Caution 1 Yurok Warning 2 Yurok Danger 3


Blue-green Algae Official Notifications

Other Information