PORT TOWNSEND — The level of toxins in Anderson Lake skyrocketed more than 46 times last week.
The popular trout-fishing lake, which was closed May 3 — only days after it was opened for the fishing season April 28 — remains closed to recreational use while the 410-acre state park around it stays open.
The level of anatoxin-a, a potent and quick-acting nerve poison, was measured at 70.0 micrograms per liter in Anderson Lake last week.
The safety threshold for the toxin is 1 microgram per liter.
The week before, the level was 1.52, so the new results of tests on samples taken last Monday— which were announced late last week — showed an increase of 46.6 times.
Anatoxin-a, a quick-acting poison that can cause convulsions and stop breathing, is a product of some species of blue-green algae, which flourishes in warm temperatures when sufficient nutrients, such as phosphates, are present.
Algae can be benign, but at times, it creates toxins.
Researchers don’t understand why some species of blue-green algae begin to produce toxins, nor what makes them increase.
A large bloom of toxin-producing algae is in Anderson Lake, said Greg Thomason, Jefferson County environmental health specialist, last week, after results from King County Environmental Labs were received.
“There was a big bloom there when I took the sample on Monday,” he said. “It didn’t look very good.
“There were wide bands of scum both at the shoreline and as far as I could see,” he said. “It not only has scum on the surface; it’s also through the water column.”
Since 2006, Anderson Lake, which is between Port Townsend and Chimacum, has been closed during parts of the warmer months because of dangerous levels of toxins, especially anatoxin-a but also microcystin, which can cause skin irritation and — if ingested over a period of many years — can result in liver failure.
The level of microcystin in Anderson Lake was measured at 1.8 micrograms last week, Thomason said.
“Six micrograms [per liter] is the danger level, so we’re well below that, but it’s coming up,” he said.
Anderson Lake is the only lake sampled in East Jefferson County that contained unsafe levels of algae-produced toxins.
In Lake Leland, north of Quilcene, the level of anatoxin-a was 0.195 micrograms per liter — “still way low,” Thomason said.
Microcystin was not detectable.
Neither toxin could be detected in Gibbs Lake, which is south of Port Townsend.
Although Crocker Lake — near the U.S. Highway 101-state Highway 104 intersection — has a bloom, no toxins could be detected, Thomason said.
“Anderson stays closed. The others are open,” he summed up.
Caution signs remain posted at Leland, Gibbs and Crocker because of the continuing presence of the type of algae that can produce toxins.
The county’s yellow caution sign warns lake users to refrain from drinking lake water and from swimming or boating in areas of scum, while also keeping pets and livestock away from it and cleaning fish well and discarding guts.
Caution is urged because the status of lake quality can change very quickly, and testing is always a week behind reality.
Why does it happen?
Researchers don’t know, Thomason said.
“A lot of people are trying to figure this out — in England, Europe, Australia, all over the world,” he said.
“A lot of people are working on it, but nobody knows.”
He said the problem has worsened worldwide over the least few years. Since it affects more and more people, more attention is being paid.
“Hopefully, we’ll know more as time goes on,” Thomason said.
“But we can’t tell you why it’s actually happening.”
All that is know is that the typical pattern, seen in lakes that are aging and are relatively shallow, is that algae blooms increase along with hours of daylight.
In the case of Anderson Lake, “even though we didn’t have very warm temperatures, we did have sunny weather,” Thomson said.
“Last year, [Anderson Lake] was able to stay open for six weeks” after the beginning of the fishing season the last weekend in April.
“That’s the big question,” Thomason said.
“Why it did that last year and why it’s doing something different this year.
“We just don’t know.”
No toxic blue-green algae has been reported in Clallam County.
Because most lakes are deeper and clearer than many in East Jefferson County, algae produced toxins are less likely, Thomason has said.
However, health officers do not test for toxins. Instead, they visually monitor lakes for signs of algae bloom.
A Discover Pass — which is $10 for one day or $30 for an annual pass, and which can purchased at state parks — is needed to visit state parks.
Algae blooms in Clallam County lakes should be reported to the Clallam County Department of Health and Human Services’ environmental health division by phoning 360-417-2258.
Anyone who observes an algae bloom at a lake is urged to phone the Jefferson County Public Health Department at 360-385-9444.
For more information about lake quality in Jefferson County, visit the environmental health website http://tinyurl.com/6z64ofy.
________
Managing Editor/News Leah Leach can be reached at 360-417-3531 or at leah.leach@peninsuladailynews.com.
