When the rain starts, fall salmon runs begin! Returning salmon swim up streams and rivers throughout the Puget Sound region to lay eggs.

But many of these salmon, particularly in urban areas, are met with a blast of pollution. Polluted stormwater runoff — the cocktail of heavy metals, oil and petroleum products, fertilizers, and other waste that washes off roads and hard surfaces when it rains — is especially and tragically toxic to coho salmon. And where the pollution is worst, it kills fish before they can spawn, putting many populations in urban areas around the Puget Sound basin at risk of disappearing.

For the first time, researchers have a lead on what contaminants in stormwater might be killing these fish. They believe the culprit is a component of car tires, which release particles onto roads. But finding the specific chemical is challenging because the manufacturing process is complicated and many of the chemicals involved are not tested for toxicity.

To help solve the problem, researchers are asking the public to report sick fish spotted in the wild. If you see a salmon behaving oddly – swimming in circles, appearing to gasp for breath, and acting disoriented, as in the video below – report it to the partner organizations working to save these fish. One of the best remedies for polluted stormwater is natural filtration, via rain gardens and other green infrastructure. Community reports will help experts decide which areas need the most help, and where to start piloting solutions.  

You can also volunteer with Soundkeeper to track the coho salmon returning to Longfellow Creek. Longfellow Creek flows though urbanized areas in Roxhill, Delridge, and West Seattle, and drains over 2,000 acres of land. This means the coho salmon in Longfellow are often exposed to urban stormwater runoff after rainfall events. Over the past few years, we’ve documented as many as 90 percent of fish dying before they spawn. Volunteers commit to once-weekly surveys, and we provide gear and training. To sign up, register for our October training or contact us with questions.

Although the Southern Resident orcas prefer Chinook, they will also eat coho, and declining coho populations are a major issue for the survival of our endangered orcas. Coho are also a source of food for other animals. And their struggles indicate pollution issues that plague the entire Puget Sound watershed. Polluted stormwater runoff is one of the largest sources of toxic contamination to our local waterways. It will take a region-wide effort to clean up the water and recover struggling salmon runs and degraded habitat.