PORT TOWNSEND — Anderson Lake, which has been closed because of toxins since May 30, remains a conundrum for public health officials, since it contains a dangerous level of poisonous blue-green algae even as other lakes within Jefferson County are clearing during chilly weather.
Public health officials are considering what to do about the toxic algae in the popular trout-fishing lake inside Anderson Lake State Park — which closed for the season on Saturday — after a year of weekly lake water sampling and testing.
Blue-green algae can produce anatoxin-a, which can cause liver damage or nerve impairment.
Small children and people with liver disease, such as chronic hepatitis, are most at risk from these toxins.
The unchanging status of Anderson Lake, which is between Port Hadlock and Chimacum, comes as the Jefferson County Public Health Department on Friday upgraded water-quality advisories on three county-owned lakes — Gibbs, Tarboo and Crocker — clearing them as safe for recreational use, although with cautions for Gibbs and Tarboo.
In Clallam County, health officials say they are observing lakes and will test them if they see a blue-green algae bloom.
Unlike Lake Anderson — which is slowly filling in and stays relatively warm — Clallam’s lakes are deeper and colder and less conducive to algal blooms, they say.
Cold no cure
Colder fall weather, which last year was believed to have an adverse effect on the potentially toxic algae in Anderson Lake, has failed to curb toxin levels in Anderson Lake this year.
“Anderson is continuing to bloom despite the cold,” said Neil Harrington, Environmental Health’s water quality manager, who has closely monitored lake water conditions since May 2006, when the lake was first closed after a dog died from drinking the water.
Toxins remain at nearly double the threshold that would make Anderson safe for public use.
The most recently tested sample of Anderson Lake water was found to have 190,000 cells per milliliter.
The threshold is 100,000 cells per milliliter. A sample testing at that level or above is considered hazardous.
The highest cell count found in the lake was 1.9 million recorded on June 23; the lowest cell count was in August at 66,000, but it soared to 460,000 shortly thereafter.
Alum treatment
One option under consideration is to treat Lake Anderson with alum to bind the phosphorous generated by the algae and force it to fall to the lake bottom.
If not carefully balanced with other chemicals that neutralize some of its effects, alum will kill fish.
Improper treatment led to a large fish kill in July in Pierce County’s Wapato Lake after water acidity levels soared.
But the treatment may never be tried.
It’s considered too expensive.
Treating the lake with alum could cost hundreds of thousands of dollars, Harrington said.
“It’s not a $200 fix.”
County officials have not discussed the options with Washington State Parks.
“What may make a lot of sense, if we can’t treat Anderson Lake, is to shift the time of year that fishing is done,” said Andrew Shogren, environmental health/water quality director for Jefferson County Public Health, in a written statement on Friday.
Testing ends for the year
Health officials have ended their weekly county lakes water sampling and testing until May.
“With the end of recreational season, we will be ending regular testing of the lakes,” Shogren said.
“However, we will continue to test for nutrients on a monthly basis, and watch for blue-green algae blooms.”
The test results collected during the past year will help officials, Shogren said, although he did not go into detail.
“With this information, we can make decisions and recommendations about the county’s lakes,” he said.
Other lakes
Public Health upgraded Gibbs Lake, near Chimacum, and Tarboo Lake, north of Quilcene, to “caution,” marked by yellow signs, removing the health advisory warning with red signs.
Crocker Lake was upgraded to clear, marked by a green sign. Crocker was formerly in the red as well.
Lake Leland, north of Quilcene, continues to be posted with a yellow caution sign.
Health officials said that the water in Lake Leland, a source of drinking water for some shoreline homes, is not safe to drink.
Gibbs, Tarboo and Leland lakes are cleared for recreational use with some cautions:
• Small children and pets should stay out of the water.
• Avoid visible scums.
• Fish caught for consumption should be cleaned in fresh water and the organs and skin discarded.
Teal Lake, which is on state land west of Paradise Bay, had high toxin levels in the summer, but was found clear of all toxins in September.
Anderson’s future
Why has Anderson Lake remains toxic while algae-generated poison in other lakes has succumbed to chillier weather is uncertain.
Calling Anderson Lake “a big pond,” Harrington said it has no inlet or outlet like other lakes in the county, trapping its waters.
“It’s got quite a bit of nutrients in it,” he added.
High levels of phosphorous make it an ideal algae breeding ground.
Anderson is also about 25 feet at its deepest point. Shallow lakes tend to have more algae growth than deep water, he said.
County health officials are studying Sandy Shore Lake, in the headwaters of Thorndyke Creek near state Highway 104, which has low levels of algae.
Harrington said the county is also looking at “depressional lakes” in Pierce, Kitsap, Skagit and Snohomish counties.
One thought is that a former dairy near Lake Anderson could have been the source of phosphorous, which was churned up when the lake naturally turned over during temperatures changes.
“What we want to know is what’s driving that spring bloom, with the end game being of determining what do we do,” Harrington said.
All Jefferson County lakes monitored have the potential to form dense scums of algae that pose a high risk and are visible around the lake’s shorelines.
The scum can range in appearance from pale cottony masses to green fuzzy blobs to slicks that look like paint spills.
Anderson Lake State Park will reopen April 29.
Lake status and more detailed recommendations can be found on the Jefferson County Public Health Web site at www.jeffersoncountypublichealth.org.
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Port Townsend-Jefferson County Editor Jeff Chew can be reached at 360-385-2335 or at jeff.chew@peninsuladailynews.com.
