Chemicals in our waterways are killing fish.

During the salmon run each fall, coho salmon enter the Duwamish River from Elliott Bay, and then swim up Longfellow Creek to spawn.

Historically, Longfellow Creek contained populations of coho, chum, and Chinook salmon, cutthroat trout, and steelhead trout. The creek was a traditional fishery dating back to the 14th century. Because of area development, Longfellow Creek, like many urban creeks, suffers from habitat and water quality degredation. Various federal and state agencies conducted surveys on coho (Oncorhynchus kisutch), Chinook (O. tshawytscha) and chum (O. keta) salmon that use Longfellow Creek as spawning habitat in order to gauge the effectiveness of stream restoration projects. During these surveys they noticed coho salmon uniquely suffered from exposure to urban stormwater runoff, a disease now referred to as Urban Runoff Mortality Syndrome (URMS).

Fish deaths caused by toxic stormwater is of particular concern as regional efforts are underway to restore endangered salmonoid species and Southern Resident Killer Whales.

Efforts to survey fish mortality in Longfellow Creek, and specifically coho females that died before being able to spawn began in 1999. When public funding was no longer available to continue these survey efforts, Puget Soundkeeper trained community volunteers to collect salmon run data and continue to monitor trends in spawning success and salmon survival. Puget Soundkeeper began monitoring the salmon trends in 2015 and continues in October every year.

Adventurous volunteers are needed to conduct salmon surveys starting in October. To be eligible to conduct surveys, volunteers must attend a 2-hour training workshop in early October.

What We’re Finding:

As coho migrate through urban streams like Longfellow, they encounter a chemical cocktail of toxic runoff from roadways and other paved surfaces. These chemicals severely disorient adult coho and result in “pre-spawn mortality” in many individuals, meaning the salmon die before reproducing.  

Previous surveys conducted by the City of Seattle and NOAA on Longfellow Creek have found pre-spawn mortality rates of up to 90% among females, an alarmingly high statistic.

Examining the number of salmon that return to Longfellow Creek every year and documenting the pre-spawn mortality rate are great indicators of the health of our local waterways.