Toxic Algae Found In Lake Burien By King County Water Resource Staff

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A toxic blue-green algae bloom was recently discovered in Lake Burien, but may not be visible in this panoramic photo (click to see larger image). Photo taken Aug. 12, 2010 by Scott Schaefer.

by Scott Schaefer

A toxic blue-green algae bloom was recently discovered in Lake Burien – whose shoreline residents have extolled the quality of its water – by King County water resource staff.

“Blue-green algae was first observed by King County staff working with lake neighbors on invasive plant control on Lake Burien on August 16,” Dennis Clark, public outreach/ stewardship coordinator for Watershed Resource Inventory Area (WRIA) 9, has informed the city.

WRIA 9 encompasses the Green/Duwamish watershed and the central Puget Sound region.

Clark said county staff took a sample of the algae and analyzed it during the week, confirming on Aug. 20 that it is blue-green algae – which can cause health problems for people and dogs.

“Residents should take steps to minimize their exposure to this algae” and keep their dogs from drinking lake water, he added. Swimmers and retrieval dogs should stay out of areas of the lake where the water is scummy.

Nitrogen and phosphorus, which come from lawn and garden fertilizers, are primary nutrients for algae,” Clark noted. “Residents can reduce the amount of nutrients and enhance the lake through a variety of steps.”

Here is detailed information about blue-green algae included in the notice from King County to Burien:

What is the algae and what does it look like?
The algae is cyanobacteria and is commonly called blue-green algae. A blue-green algae bloom often looks like green paint floating on the water and is hard to pick up or hold. It can take the form of a scum. Despite its name, it can be a range of colors including bright green, blue-green, olive, yellow-brown, and red. Because the algaeis often at the surface, the wind blows it around and it can get caught up in shoreline vegetation.

King County steward Dennis Clark.

Why is blue-green algae a cause for concern?
The Washington State Department of Ecology notes that some blue-green algae blooms pose a human health concern and have killed pets and livestock. Although most blue-green blooms are not toxic, some blue-green algae produce nervous system or liver toxins. Toxicity is hard to predict, especially by sight. The size or intensity of the scum do not indicate the toxicity. A single species of algae can have toxic and non-toxic strains. A bloom that tests non-toxic one day can become toxic the next day.

People may become ill after swimming or water skiing in lakes with toxic blue-green algae. Human health effects may include stomach pains, vomiting, diarrhea, skin rashes, and nerve and liver damage. Pets and wildlife have died after exposure to toxic blue-green algae in Washington lakes.

What is the type and concentration of blue-green algae in Lake Burien?
The type of blue-green algae found on Lake Burien produces toxins that harm the liver, known as hepatotoxins. The analysis showed this type of toxin present at a concentration of 5.72 micrograms per liter. This concentration is just below the state’s proposed recreational guideline of 6 micrograms per liter. Note that this sample represents a shoreline concentration as opposed to a whole lake average. Because the toxin is concentrated mostly in the algae, in this case found along the shore, concentrations of the toxin in the open water of the lake may well be lower.

How should I reduce my exposure to this algae and its toxins?
Lake Burien residents should take steps to reduce their potential exposure to toxins that may be in the water:

  • People should avoid swimming, playing, or boating in areas where the water is scummy or blue-green algae has accumulated.
  • Swimmers should take care to minimize accidental ingestion of water.
  • Clean fish well and discard the guts.

The most immediate health risk – given the current low level of toxins present – is to dogs. Owners should take care to keep their dogs from drinking lake water. Owners should avoid “retrieval” games with dogs who will ingest water when fetching balls or sticks in the water. Dogs should be kept out of the scum because they can ingest the algae when cleaning themselves.

How long is the algae going to be a problem?
Blue-green algae will die out with the onset of cold weather but may be present in the lake into November. King County staff will sample algae every two weeks if algae continue to be reported. The Washington State Department of Ecology pays for the cost of analyzing samples.

Cyanobacteria health effects may include stomach pains, vomiting, diarrhea, skin rashes, and nerve and liver damage.

How can I learn more about blue-green algae?
A good source of information in the Washington State Department of Ecology’s website:

More general information on algae in local lakes is here (PDF file).

What if I see blue-green algae in the lake at my property?
Please report sightings of blue-green algae to the Miller/Walker Creek basin steward Dennis Clark, [email protected], or at 206-296-1909. Reports on the presence of algae will help staff determine when and where to take future samples.

How can I stay informed of the results of future algae samplings?
Sampling results will be posted at the Miller/Walker basin web page:

If algae conditions worsen significantly, you will be notified through this newsletter, local media, and notices sent to shoreline properties. You may contact Miller/Walker Creek basin steward Dennis Clark, [email protected], or at 206-296-1909 at any time to learn more.

Is there anything we can do to reduce the likelihood blue-green algae will recur in future years?
A big driver of algae blooms are nutrient inputs including nitrogen and phosphorous. Residents can reduce the amount of nutrients and enhance the lake through a variety of steps. Many of these steps are associated with lawn and garden care. For more information, please see the “Living with Lakes” website:

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5 Responses to “Toxic Algae Found In Lake Burien By King County Water Resource Staff”
  1. NoWaterfront says:

    Useful information for the tiny handful of people who actually have access to Lake Burien…

  2. watching says:

    Lake Burien has had a Lake Steward for 34 years. The lake is checked weekly. This algae has popped up a number of times over the years and has always been reported to the County. Interesting that the basin steward reported it to the city – for whatever reason? Nobody has ever been made ill. The toxin has never reached the stage where people should be worried about it, but the shoreline residents know about it from the shore club and if they wish they stay away from it for the short period of time that it appears. There has been less of it, and less often, in recent years because fewer residents use fertilizers and pesticides. it is also present in other local lakes and occasionally along creeks and streams.

  3. watching says:

    Lake Burien has had a lake steward for 34 years, the water is tested weekly and a report is sent to the County. This particular algae, and several others, appear off and on. Nobody has ever been made sick or hurt by them. They have never reached a level that hurts people and they disappear in a matter of a week or so. The Shore Club always advises residents of them so nobody is taken by surprise. We are seeing less of them, and less often, over the years because fewer residents are using pesticides and fertilizers. The other lakes in King County also experience these blooms, as well as local creeks and streams. Its a fact of life living on inland lakes and waterways.

  4. Eaton B. Verz says:

    Sounds to me that we need another car tab tax to prevent this from happening in the future! I’ll bet it was really caused by an “outsider” sneaking onto the lake!! Quick, hire a security force to keep the riff raff away!!!!

  5. Ed Dacy says:

    I have attended almost all of the testimony before the City Counci on the SNP. What I have been hearing is that Lake Burien is almost as pristine as an alpine lake. This bloom is a shock to me.

    From what I have been told it is primarily caused by fertlizer run off that buffers in place around the lake are supposed to prevent. It sounds like to me that someone on the lake as used fertlizer within the current buffer, or perhaps the buffer is to small. I think it is probably someone not observing the buffer, as the current buffer seems large enocugh to me. Hopefully this practice will stop in the future so thaat the lake will remain as pristine as it has been advertised.

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