Researchers at a fish hatchery near Suquamish in Kitsap County are trying to identify the toxic substance in storm water runoff that deadens coho salmon in streams, prevents them from spawning and causes deformities in coho embryos.
Observers have noticed coho seemed confused and turn onto their sides a few hours after a rainstorm.
Researchers with National Oceanic and Atmospheric Administration and the Suquamish Tribe are conducting tests at the Grover's Creek Hatchery.
They are placing coho in samples of storm water. After an hour or two the fish start bumping into the sides of their tanks and keeling over.
Researchers haven't yet identified the toxic substance, but the work may lead to ways to control runoff in urban areas to protect salmon in streams.
(copyright 2013 Associated Press)