PORT TOWNSEND — Something new is growing in Anderson Lake, and it isn’t good.
“For the first time ever, we have a new genus of toxic algae that has never shown up in our lakes before,” said Greg Thomason, Jefferson County environmental health specialist.
Coelosphaerium — a type of blue-green algae known to sometimes produce the powerful nerve toxin anatoxin-a — was discovered in a sample that was taken Sept. 10 from Anderson Lake west of Chimacum.
It is the first time this particular type of blue-green algae has been found in any East Jefferson County lake during six years of testing. Thomason said he didn’t know where it came from.
“This is not a good sign,” Thomason said. “Something different is going on here.
“It doesn’t point in the right direction.”
Toxin-producing blue-green algae typically found in the county’s lakes are anabaena, aphanizomenon and microcystis.
All three produce the potentially deadly anatoxin-a, while microcystis also can produce microcystin, which can cause skin irritation and nausea over the short term and liver damage if ingested over a long period of time.
Coelosphaerium “is something new,” Thomason said.
“It may account for our getting anatoxin later in the season.”
Thomason had been puzzled by recent test results of water samples taken from Anderson Lake — which has been closed for most of the summer because of elevated levels of anatoxin-a — that showed the level of that toxin on the rise during a season when it typically falls.
Test results received Friday found 15.3 micrograms of the toxin per liter of water.
That’s more than 15 times the safety threshold of 1 microgram per liter for anatoxin-a, which can cause paralysis and lead to death by stopping breathing.
The new level represents a surge from the week before, when the level of anatoxin-a in Anderson Lake had risen to just above the safety threshold: 1.43 micrograms per liter.
And prior to that, the levels of the toxin had been so low earlier this month that the county public health department had recommended the lake be reopened.
Mike Zimmerman, ranger in charge of the state lake, decided against that because — given the history of the lake — he feared toxin levels would rise again and it would have to be closed soon after reopening.
The lake will remain closed for the rest of the season.
The 410-acre Anderson Lake State Park around the lake remains open for recreation until the end of October. A Discover Pass is needed to park there.
The rise in toxins so late in the season is atypical, Thomason said.
“Anderson Lake just keeps going up,” he said.
“I don’t know if it is a fluke or a trend for the future.
“We’ve never seen it die off and then come back up late in the season.”
Because of the changes in the lake, the county public health department, which had decided to stop sampling at the end of this month, will continue for a week or two in October, Thomason said.
“We plan to stay with it,” he said.
“It’s definitely setting a new pattern or doing something crazy this year. We want to document it as much as we can.”
Only an estimate was available for anatoxin-a levels in Leland and Gibbs lakes. That estimate is that only a trace exists in those lakes.
No microcystin was found in Lake Leland, which is north of Quilcene, while a trace was found in Gibbs, which is south of Port Townsend.
Caution signs stay up at both lakes because they contain the types of algae known to sometimes produce toxins.
Blue-green algae is naturally occurring and usually benign, but at times, certain species begin producing toxins.
Researchers don’t understand what sparks the production of toxins from some species.
Gibbs Lake has scum and bloom, Thomason said.
“Stay away from scum,” he said. “That’s where the concentrated toxins are.”
No toxic blue-green algae has been reported in Clallam County, where health officers do not test for toxins; instead, they visually monitor lakes for signs of algae bloom.
Report algae blooms in Clallam County by phoning 360-417-2258.
Report algae blooms in Jefferson County by phoning 360-385-9444.
For more information about lake quality in Jefferson County, visit http://tinyurl.com/6z64ofy.
Managing Editor/News Leah Leach can be reached at 360-417-3531 or at leah.leach@peninsuladailynews.com.
