Swimmers, boaters urged to stay out of certain Clear Lake areas because of blue-green algae

The "Follow This Story" feature will notify you when any articles related to this story are posted.

When you follow a story, the next time a related article is published — it could be days, weeks or months — you'll receive an email informing you of the update.

If you no longer want to follow a story, click the "Unfollow" link on that story. There's also an "Unfollow" link in every email notification we send you.

This tool is available only to subscribers; please make sure you're logged in if you want to follow a story.

Please note: This feature is available only to subscribers; make sure you're logged in if you want to follow a story.


Lake County health officials are urging residents and visitors to stay out of certain areas of Clear Lake for the time being because of toxic blue-green algae and the potential health risks it poses to humans and their pets.

As is often the case during the warm weather months, routine testing has turned up elevated levels of an algae-related toxin called microcystin in the lower arm of the lake, around the city of Clearlake.

It’s the first time this season that routine cyanotoxin testing conducted each year by the Big Valley Band of Pomo and the Elem Indian Colony have reached levels triggering warnings by health officials and comes after several days of very high temperatures and little wind last week, said Angela DePalma-Dow, invasive species program coordinator for the Lake County Water Resources Department.

Four areas are of particular concern, including the water around Austin Park Beach and Redbud Park, both in Clearlake. Both locations also had high microcystin levels last August, according to state records.

Dangerous levels of the substance also have been measured in recent test samples from Lily Cove, just north of the city, and from Cache Creek near Shady Acres Campground in Clearlake, public health and water quality officials announced Tuesday.

The findings prompted public health officials to advise people to stay out of the lake and creek in those four areas, avoiding direct contact with the water through swimming and other activities. Exposure to microcystin can cause skin irritation, digestive issues and liver damage.

People also should avoid personal watercraft and boating in those areas because of the possibility that any dangerous substances could become aerosolized and inhaled, officials said.

In addition, pet owners should keep their animals away because of their tendency to drink whatever water is in front of them and the possibility their critters might lick their fur if it becomes wet, officials said.

Lower levels of microcystin have prompted public health officials to issue advisories about contact with water of Buckingham Park and in Jago Bay, as well.

Blooms of blue-green algae — technically cyanobacteria, not true algae — have become increasingly common around the planet during recent years of rising temperatures, though different kinds of organisms and types of toxin are sometimes involved.

“This is a very naturally occurring situation that happens all over the world,” Lake County Health Services Director Denise Pomeroy said. “It can happen in any body of water.”

Conditions change rapidly, and a few cool, windy days could reduce the algae bloom and eliminate the problem, DePalma-Dow said.

“Conditions change all the time,” DePalma-Dow said. “This lake is like multiple personalities.”

You can reach Staff Writer Mary Callahan at 707-521-5249.

Please read our commenting policy
  • No profanity, abuse, racism or hate speech
  • No personal attacks on other commenters
  • No spam or off-topic posts
  • Comments including URLs and media may be held for moderation
Send a letter to the editor
*** The system is currently unable to accept new posts (we're working on it) ***

Our Network

Sonoma Index-Tribune
Petaluma Argus Courier
North Bay Business Journal
Sonoma Magazine
Bite Club Eats
La Prensa Sonoma
Emerald Report
Spirited Magazine