A recent sheen on Ellis Pond is caused by decomposing algae and the pollen from local cottonwood trees, according to the city, and the city is asking residents and pond visitors to refrain from feeding ducks.
Feeding the ducks can cause fertilization of the algae, according to the city newsletter released this week. The sheen is expected to disappear in the rainy weather, the city reported.
Ellis Pond is at 4590 90th Ave SE, Mercer Island.
Mercer Island provided the following information about Ellis Pond:
Recent visitors to Ellis Pond may havenoticed an unusual sheen on the pond's surface in the last few weeks. This sheen, which appears oil-like and gray, is likely the result of decomposing algae and aquatic plants that flourished during recent warm sunny weather.
Tricia Shoblom, Environmental Specialist with the Washington Department of Ecology's Northwest Office, indicated that debris and pollen from the surrounding cottonwood trees can also cause the surface of small ponds to appear dull or oily. Shoblom and the City of Mercer Island suggest that park visitors refrain from feeding the pond's duck population, as this encourages more ducks to populate the small pond and ultimately fertilize the algae. The sheen has begun to dissipate over the past several days, and is expected to disappear with the ongoing rain this week. For more information, please contact Alaine Sommargren,Mercer Island Parks Natural Resources Specialist, at (206) 275-7879.
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