Lake Burien Toxic Algae Levels Continue To Decrease

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Dennis Clark, Miller/Walker Creek Basin Steward, sent us an update about levels of the toxic blue-green algae recently found in Lake Burien:

On Tuesday, September 14, a water sample was taken from Lake Burien and analyzed for the presence of toxins in the algae.  Results came back Friday (Sept. 17).

The latest sample showed a substantial decrease in the algae toxin (microcystin) from 6.0 micrograms per liter (on September 7) to 2.68 micrograms per liter (on Sept. 14).  This new concentration is well below the state’s proposed recreational guideline “caution level” of 6.0 micrograms per liter.  Although this latest result was far below the state guideline, it came from a sample of visibly clear lake water, unlike previous samples that contained algae scum in which the toxins are more concentrated. This suggests that the toxin may still be present in higher concentrations in any algae scums that do remain around the lake.

We will take another sample Monday.

With the cool, rainy weather forecast for the next few days, we would expect the concentrations to continue to diminish.

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