Study: Highway runoff kills salmon, but there’s a fix

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SEATTLE (AP) — New research says highway runoff is killing adult coho salmon in Puget Sound but simple filtering methods can help fish survive.

The study published Thursday in the Journal of Applied Ecology finds that salmon exposed to untreated highway runoff in controlled experiments died within a few hours. Fish survived if they were immersed in runoff that had been filtered through a soil column, similar to a rain garden.

Lead author Julann Spromberg says it offers pollution prevention that are effective and inexpensive. Heavy metals and PAHs weren’t enough to kill fish, but scientists haven’t pinpointed what exactly in the runoff is killing fish. Doing so can help control those toxics at its source.

In the meantime, the study suggests that rain gardens and other so-called green stormwater infrastructure should be incorporated where possible.

The study included researchers from NOAA Fisheries, U.S. Fish and Wildlife Service, Washington State University and the Squamish Tribe.

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