Salmon, stormwater and streets – a toxic mix

Urban watercyle

Alan Lande, KUOW 94.9 Public Radio

Have you ever seen one of those fish drawings near the street on a storm drain – a stencil saying something like, “don’t dump, drains to stream.” And even though you might think of salmon as all living in pristine, beautiful rivers, it turns out that polluted stormwater runoff from developed areas and roads and highways threatens these fish too.

Coho salmon have been dying in urban streams throughout the Puget Sound region before they have the chance to swim back upstream and spawn, raising concerns about these fish populations. The dying fish corresponded to the amount and intensity of rainfall in urban areas, and so scientists from the National Oceanic and Atmospheric Administration (NOAA) have been working in partnership with the Suquamish tribe to pinpoint the exact cause.

Recently, NOAA confirmed that polluted stormwater runoff from roads and highways are causing coho salmon deaths. In the study, fish exposed to the polluted water collected running off from highways caused the fish to lose their sense of direction and keel over onto their sides. While it’s still unclear whether the fish are harmed from one specific pollutant or a combination of them, the research raises concerns for the future as sprawling urban development continues.

Polluted stormwater runoff is recognized as one of the most serious threats to Puget Sound, and is a leading cause of water quality problems nationwide. As areas change from rural to suburban and urban, the impacts of all the roads, rooftops and other hard surfaces harm our rivers and streams as water runs quickly off these surfaces, quickly dumping a mix of pollutants into local waters instead of soaking gradually into the ground where pollution can be filtered.

Urban areas will continue to grow, so finding ways to make them benefit people and rivers by using smarter approaches to water management, like rain gardens and green roofs to reduce pollution and flooding, will be critical going forward.

That’s why we’re working to protect clean water by advocating for policies, like updates to national stormwater rules, and improvements to stormwater permits that will help communities manage water to better protect streams nationwide, and to help fish, like salmon in the Puget Sound region.