LAKE COUNTY, Calif. – Lake County Public Health is urging boaters and recreational users to avoid direct contact with or use of waters containing blue-green algae, or cyanobacteria, in the Richmond Park and Clearlake Oaks areas.

The recommendation is based on the potential health risks from the algae, which is currently blooming in all three of the lake’s arms – Upper arm, Oaks Arm and Lower Arm.

Bloom conditions can change rapidly and wind and waves may move or concentrate the bloom into different regions of the Clear Lake, officials reported.

Water monitoring is done by Big Valley Band of Pomo Indians and Elem Indian Colony.

The county said that on Tuesday lakewide sampling indicated that blooms were present in several locations on Clear Lake. Water samples have been submitted to the lab for cyanotoxin analysis, but a preliminary analysis on five sites using the ABRAXIS field strips was performed.

One site, Richmond Park, indicated at least 10 µg/L, considered a warning level, while another site by the county park in Clearlake Oaks, indicated at least 20 µg/L, which is a danger level, according to the county report.

County officials expect the pending lab results will confirm those levels; they said they will report on the results of that testing.

In the case of the Clearlake site, the county said it is close to a drinking water supply. Drinking water at the site was tested last on July 10 and was below the Environmental Protection Agency’s recommended guideline of 0.3 µg/L and was safe to drink. Sampling of drinking water at the site will next occur on Monday, July 23.

A danger sign was posted at the Clearlake Oaks site on Wednesday, officials said.

The Public Health Department gave warning signs to the bar and grill at Richmond Park on Wednesday and it is strongly recommended that the warning signs are posted immediately and remain posted until further notice.

Blue-green algae can pose health risks, particularly to children and pets. The county urges people to choose safe activities when visiting the Oaks arm and parts of the lower arm of Clear Lake and wherever blooms are visible. It is strongly recommend that people and their pets avoid contact with water, and avoid swallowing lake water in an algae bloom area.

Cyanobacteria, also known as blue-green algae, are common and natural to our waters and found throughout California. Cyanobacteria thrive in nutrient-rich water and can multiply rapidly to form blooms and scums, particularly during the warm days of summer and early fall.

The algae bloom resembles thick pea soup or spilled paint on the water’s surface. It can appear as cut grass in the water or blue-green, white or brown foam, scum or mats that can float on the water’s surface and accumulate along the shoreline and boat ramp area.

Signs of a toxic bloom may include: a large number of dead fish, waterfowl or other animals, or sudden, unexplained sickness or death of a cat or dog that has been exposed. It is not possible to tell if cyanobacteria are toxic by looking at them.

Recreational exposure to toxic blue-green algae can cause eye irritation, allergic skin rash, mouth ulcers, vomiting, diarrhea, and cold and flu-like symptoms.

Pets can be especially susceptible because they tend to drink while in the water and lick their fur after. Possible health effects of animal exposure to a toxic bloom include weakness and staggering, difficulty breathing, convulsions, vomiting or diarrhea.

A blue-green algae bloom is not stringy, made up of long bright grass-green strands that feel either slimy or cottony. This is harmless green algae. It’s also not mustard yellow in color; this probably is pollen.

Get medical treatment immediately if you think that you, your pet, or livestock might have been poisoned by blue-green algae toxins. Be sure to alert the medical professional to the possible contact with blue-green algae.

Also, make sure to contact the local county public health department at 707-263-1090.