Discharges containing the de-icing fluid -- variations of glycol, similar to antifreeze -- are harmful to fish and other aquatic life. Bacteria break down the fluid, robbing fish of oxygen in the Columbia Slough, where the water is emptied.Read the whole article here: Portland airport's de-icing system harms fish - USA Today
As glycol-laden water passes into the lower portion of the slough, it encounters habitat for juvenile coho and chinook salmon, members of the Columbia Slough Watershed Council wrote the state Department of Environmental Quality in 2004.
Susan Aha, a Port water-quality manager, said the chief problem with the current system was that it was based on models indicating that water flows in the slough ran 100 cubic feet per second.
"Since then we've come to realize that flows are much lower," Aha said, averaging 50 to 60 cubic feet per second. Many days there is no measurable flow at all.
The result of lower water flows is that the concentration of glycol in the slough is not sufficiently diluted.
The Port is looking at piping discharges directly into the Columbia River as part of enhancing its system. Current discharges eventually get there anyway, after passing from the slough to the Willamette River and then to the Columbia.
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