As a precaution, health officials recommend that individuals of all ages and pets avoid swimming in or ingesting lake water in these affected areas. Avoid contact with areas in and around algae mats. Families should exercise caution in keeping children and pets away from the water in these areas.
In response to public complaints of foul odors and floating scum on the lake surface, Environmental Health reported that it has performed bacteriological water testing in the affected areas and has determined the observations are not related to a sewage discharge.
A sampling and analysis done by Lake County Vector Control District indicates the presence of lyngbya, a relatively uncommon form of blue-green algae bloom in Clear Lake, according to Environmental Health.
Some types of blue-green algae can release toxins and allergens in the water. Lyngbya, the identified species, is known to cause skin irritation resulting in dermatitis.
County Health Officer Dr. Karen Tait advised the public to keep away from areas with visible algae mats and to avoid direct contact with affected water, including drinking the water and recreational activities such as swimming, wading and water skiing.
According to the Lake County Water Resources Division of Public Works, this type of algae forms mats on the lake bottom that, during photosynthesis, release sulfur-containing gases. These gases release strong odors similar in smell to sewer gases and also create buoyancy that causes the mats to rise to the surface.
Once at the surface, winds then move the algal mats to the shoreline, thickening the mats and creating nuisance odors. The mats form blue-green, black, and/or gray clumps that rise to the surface, and as the mats decay, they bleach to a grayish-white color.
Although not one of the commonly occurring algal bloom species on Clear Lake, lyngbya previously was identified on Clear Lake most recently in 2001, in 1997, and also during the mid-1980s.
Clear Lake is a nutrient-rich lake with four predominant types of blue-green algae identified to cause blooms.
The lyngbya species is yellow-brown filamentous algae with a self-protective mucus, which makes it resistant to control methods.
In an effort to mitigate the nuisance caused by these blooms, the California Department of Food and Agriculture is using air boats to help reduce the presence of algae mats in the affected areas. Local fire districts, staff from the City of Clearlake, and local volunteers also are working together to help break up the mats.
Shoreline property owners within the affected areas are encouraged to use portable re-circulating pumps to spray lake water to break up unsightly slicks and reduce nuisance odors.
Environmental Health has posted health advisory signs, which will remain in effect, on public beaches and access points near the affected areas, which will remain in effect. Environmental Health and Vector Control will continue to test and monitor the affected areas.
For more information, contact Lake County Environmental Health at 707-263-1164 during regular business hours.
