LAKE COUNTY, Calif. — Officials reported that recent testing of sites on Clear Lake have shown dangerous levels of cyanotoxin.

While much of the aquatic plant growth visible in the lake right now is harmless, cyanobacteria, when present in sufficient abundance, can produce cyanotoxins, which pose health hazards to humans, livestock and pets.

Water monitoring is regularly conducted by the Big Valley Band of Pomo Indians with assistance from Robinson Rancheria EPA Department, at approximately 15 Clear Lake sites.

All verified results are publicly available here.

Currently, concentrations of microcystin cyanotoxin at numerous locations around the lake are extremely high.

During recent sampling conducted on Tuesday, Aug. 25, EPA lab-confirmed testing indicated the highest levels of two toxins that have been recorded on Clear Lake during water sampling events: a microcystin (liver toxin) result value of almost 26,000 micrograms per liter (µg/L) and an anatoxin-a (neurotoxin) result value of almost 13 µg/L.

The nine locations with DANGER levels of Cyanotoxin are the following (also see yellow CAUTION indicators on the map, below):

— Clearlake Oaks (CLOAKS01, Oaks Arm).
— Elem Indian Colony shoreline (ELEM01, Oaks Arm).
— Sulphur Bank Mercury Mine shoreline (SBMMEL01, Oaks Arm).
— Lily Cove (LC01, Lower Arm).
— Austin Park (AP01, Lower Arm).
— Redbud Park (RED01, Lower Arm).
— Shady Acres (SHADY01, Cache Creek).
— Jago Bay (JB, Lower Arm).
— Lakeport, Library Park (LPTNT, Upper Arm).

Public Health urges boaters and other recreational lake users to avoid direct contact with or use of waters containing cyanobacteria in Lake County and to follow all posted signage regarding safe activities.

This recommendation is based on the recent toxin results as well as the potential health risks from cyanobacteria, which is currently blooming at varying levels throughout the lake.

Cyanobacteria can pose health risks, particularly to children and pets. Officials urge people to choose safe activities when visiting natural bodies of water, particularly where blooms are visible.

It is strongly recommended people and their pets avoid contact with and avoid swallowing lake water in areas where algal blooms are present.

Conditions can quickly change. Before recreating in Clear Lake, check the most recent monitoring results.

For current cyanotoxin lab results, please visit the Big Valley Band of Pomo Indians cyanotoxin monitoring website and Clear Lake Water Quality Facebook page.

Further resources are available at the following webpages:
http://www.lakecountyca.gov/cyanobacteria/
http://www.lakecountyca.gov/cyanohealth/

California Portal on Harmful Algal Blooms:
https://mywaterquality.ca.gov/habs/index.html

CDC guidance regarding harmful algal blooms can be found here:
https://www.cdc.gov/habs/materials/factsheet-cyanobacterial-habs.html