Highway runoff blamed for salmon deaths in Puget Sound

Washington State University researchers have determined that toxic runoff from highways is leading to the death of salmon in the Puget Sound. The researcher say that simple filtering methods could prevent salmon from being killed by the toxic runoff. To come to the conclusion that runoff water from the highways are killing the fish, the researchers took a salmon and placed it into a tank of pure runoff water.

Over the next 24 hours they watched the fish become ill until it died after becoming lethargic and losing all sense of orientation. To prove that the fish could live after using their filtering methods, the researchers took runoff water and ran it through columns of sand and soil similar to a rain garden.

Fish placed in those tanks of filtered water surprised researchers by being unaffected by heavy metals and oils produced in the lab. Meanwhile runoff collected from a highway in Seattle proved lethal. This has led the researchers to the conclusion that something they aren't measuring is killing the fish.

The team needs to know what exactly is causing the fish deaths to be able to target the source of the toxin. In addition to the researchers from Washington State University, NOAA Fisheries, US Fish and Wildlife Service, and Squamish Tribe researchers participated in this study.

SOURCE: Bellingham Herald