PORT HADLOCK — Anderson Lake will remain closed Saturday on the opening day of fishing season because test results found too high a concentration of a blue-green algae toxin to permit recreational use, the Jefferson County Health Department said.
This weekend will be the first time the lake has been closed for the fishing season opener since toxic blue-green algae was first discovered there in 2006. The park will remain open.
Preliminary results of the first round of testing done in Jefferson County lakes since October found 7.3 micrograms of anatoxin-a — a neurotoxin — per liter of water in Anderson Lake, south of Port Townsend.
“The draft state guidance recommends cutting off recreational exposure at 1 microgram per liter,” said Neil Harrington, Jefferson County Public Health water quality manager, Thursday.
“The verdict is that it’s toxic,” he said.
“It’s got such a huge, dense scum on it, with anatoxin-a, and that is what killed the dogs,” he added. “It’s unfortunate.”
Two dogs died from drinking Anderson’s water in spring 2006. That was the first indication that the popular trout fishing lake was poisoned.
Although the neurotoxin anatoxin-a does not harm fish or amphibians, it can cause convulsions or even death in mammals, Harrington said.
Earlier this year
Harrington said he didn’t know why the toxin had shown up earlier in the year than in the past.
Anderson Lake State Park is expected to remain open for equestrian, hiking and biking activities, but use of the lake is banned, he said.
The fear is of physical contact with the water, he said.
Not only is a neurotoxin potentially deadly, it can act quickly.
“The dogs were dead 20 minutes” after contact with the lake in May 2006, Harrington said.
At least two weeks
Anderson Lake will be closed for at least two weeks and probably more.
The next test will be on Monday, with results from King County Environmental Labs due by Thursday, but the county health department wants at least two weeks of test results showing that a lake is clear before permitting usual recreational use, Harrington said.
“Our experience is that it may take much longer than two weeks for the bloom to dissipate.”
Blooms tend to begin in the spring slightly toxic and then “get really, really toxic” in the summer, he said.
In 2008, the lake was found to have 100,000 or more micrograms of toxin per liter of water at its worst, he added.
“Last summer, it was closed most of the summer,” he said.
“I hope that it’s not” this year.
Weekly testing will continue through September, he said.
County tests found microcystin toxin in Gibbs Lake near Chimacum and Lake Leland north of Quilcene.
It’s not enough to close the county lakes to recreation, but the health department warns against eating fish from the lakes, drinking the water or swimming in them.
They can be used for such activities as boating, catch and release fishing, hiking, bicycling and bird-watching.
Microcystin is a cyanotoxin that can cause serious liver damage, and “fish are a potential pathway,” Harrington said.
“Right now, it’s just potential at those lakes [Gibbs and Leland],” he said. “The concern is that fish might have microcystin in their tissues.”
No toxic algae has been discovered in Clallam County.
The Clallam County Health Department does not actively test water samples of lakes, instead relying on visual monitoring for algae blooms.
Where does it come from?
Toxins are produced by algae, but not all algae produce toxins.
Scientists do not know what causes algae blooms to become toxic.
Algae blooms in fresh water lakes, which occur naturally, are fed by nutrients such as nitrogen or phosphorus, which can come from fertilizer, sewage, lake sediments or other sources, Harrington said.
Since 2006, Jefferson County Public Health has tested water samples from Lake Leland, Anderson Lake and Gibbs Lake to determine what species of algae are present and at what concentration.
This year, the department also is collecting samples for nutrient analyses and physical data to determine possible causes for the blue-green algae blooms. The study is funded by a $45,000 state Department of Ecology grant.
The county health department expects to complete the study early next year, Harrington said.
No conclusions are possible yet, but Harrington doesn’t think the source is either fertilizer or sewage, because of the paucity of potential sources near the lake.
“One thing I’ve been scratching my head about is, where does this come from?” he said.
Harrington speculated that the source could be the algae itself. Each year, the algae die and sink to the bottom of the lake. In the spring, the lake “turns over,” bringing up sediment and the nutritional content of the dead plants — essentially, recycling the phosphorus.
Although he will know more after the study is complete, Harrington said he thought the blooms of algae “may have more to do with light availability than with temperature. It’s not that warm out there, but it’s bright.”
Jefferson County Public Health maintains an updated database of lake monitoring information at www.jeffersoncountypublichealth.org/. The department can be reached at 360-385-9400.
Algae blooms in Clallam County lakes should be reported to Clallam County Department of Health and Human Services environmental health division at 360-417-2258.
Port Townsend-Jefferson County Editor Jeff Chew can be reached at 360-385-2335 or at email@example.com.
Managing Editor Leah Leach contributed to this story.