PORT TOWNSEND — With warm weather conditions combined with naturally recurring elements, Anderson Lake has become a prime haven for deadly cyanobacteria.

“With the heat wave, we’re really going to have to be careful,” said county Environmental Health Director Mike McNickle, addressing the county Board of Health on Thursday.

He referred to temperatures expected to rise this weekend, mixing with naturally recurring nitrogen and phosphorous that makes for fertile algae blooms around the lake.

Those blooms contain cyanobacteria.

Several different toxins have run the cycle in the lake, some more deadly than strychnine.

“Toxins in the lake are competing with each other, so hopefully they will kill each other off,” McNickle said.

The 70-acre lake — the centerpiece of Anderson Lake State Park near Chimacum –was closed June 4 after two dogs drank its waters and died during a blue-green algae bloom.

Since then, dead muskrats have been found around the lake, said McNickle, whose department has been water-sampling lakes Anderson, Leland and Gibbs, and visually monitoring seven other county lakes for algae blooms.

Dangerously high

Anderson Lake’s toxic cyanobacteria levels remain dangerously high, said McNickle, and the popular park remains closed to the public until further notice.

Other lakes around Jefferson County remain clear of cyanobacteria, which appear in so-called blue-green algae blooms, said McNickle.

Higher than ever, the cyanobacteria level in the 70-acre Anderson Lake was tested at 1.3 million cells per milliliter, said McNickle, adding that the lake is now testing extremely high for saxotoxins.

Saxotoxins are similar to what causes paralytic shellfish poisoning in saltwater locations.