Clean Water Under the Bridge

A newly completed bioswale at the foot of Seattle’s Aurora Bridge now removes pollutants from stormwater running into Lake Union. Myriad partners from public agencies, private businesses and nonprofits collaborated to make the Aurora Bridge Bioswale a reality, with major pollution-cleanup benefits – this piece of green stormwater infrastructure filters two million gallons of runoff each year. Projects building off this model could make an even bigger impact – including a proposed bioswale under Seattle’s I-5 bridge that could filter more than 900 million gallons of stormwater annually.  These types of projects are an important part of tackling pollution.  

Wherever vehicles drive over impervious surfaces, tiny particles of tire dust wind up in the water running off roadways when it rains, entering our waterways along with other toxic pollutants. Recently, scientists from Washington State University, U.S. Fish and Wildlife Service, the National Oceanic and Atmospheric Administration, and the University of Washington Tacoma discovered that one chemical present in all types of tires – 6PPD – is particularly harmful to salmon. While there is no known replacement for 6PPD, we do know that green stormwater infrastructure – like bioswales and rain gardens –is effective at removing this and other harmful substances from runoff. 

Watch the video below to learn more about the innovative approaches TNC and partners are taking to combat stormwater here in Washington. 

Thank you to the partners that made this possible: 

  • Boeing 

  • Clean Lake Union 

  • Department of Commerce  

  • Hess Callahan Grey Development 

  • KPFF 

  • Salmon Safe 

  • Stephen C. Grey and Associates 

  • The Nature Conservancy in Washington 

  • Weber Thompson 

  • Site Story

  • Adobe 

  • City of Seattle 

  • Fremont Dock Company 

  • Groundspeak/Geocaching 

  • Hal Real Estate 

  • Hess Callahan Partners 

  • Parametrix  

  • Rushing 

  • Spear Street Capital 

  • Tableau/Salesforce  

  • Turner Construction Company 

  • Washington State Legislature 

  • Washington State Department of Transportation


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