The Secret Killer of Puget Sound Salmon — The Nature Conservancy in Washington

By Eric Wagner, Freelance Author

The Ship Canal Bridge is a double-deck metal truss that looms practically 200 ft above Portage Bay, between Lake Washington and Lake Union in Seattle. Greater than 200,000 automobiles cross over this bridge on daily basis, as they’ve for 50 years, whipping north or south alongside the twelve lanes that make up Interstate 5. Stand beneath the bridge at North Passage Level Park, on the shore of Portage Bay, and you’ll hear the surging hum of all these tires as they whoosh far above you. And should you occur to be within the park throughout one of many area’s many rainstorms—even one which appears temporary and light-weight—you possibly can watch veils of water cascade from the bridge overhead into the bay beneath. Beneath your ft, in the meantime, you hear speeding water because it gathers from hundreds of acres of Inexperienced Lake, Aurora, and north Seattle streets, consolidated right into a single pipe that dumps it, untreated, into the canal.

That stormwater, scientists now know, is stuffed with poisonous chemical compounds. However one particularly has caught their consideration: N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine; or, because it’s known as in shorthand, 6PPD-quinone. An industrial chemical, 6PPD-quinone is used as an antioxidant in rubber tires. Each time a automotive or truck drives, friction causes tiny bits of tire to flake off onto the highway. These bits and all of the toxins they include—together with 6PPD-quinone—lie there till stormwater picks them up and carries them away as runoff to the closest stream, creek, lake, or river.