Each year, dedicated Puget Soundkeeper volunteers survey coho salmon as they return to Longfellow Creek, or t?áwi (pronounced t-AH-wee), in Lushootseed. The waterway runs through Roxhill, Delridge, and West Seattle, and drains over 2,000 acres of land. This means the coho in Longfellow Creek are exposed to stormwater laden with toxic substances, including the tire chemical derivative 6PPD-Q.
This chemical is lethal to coho and several other species of fish, and sublethal impacts are still being studied. Puget Soundkeeper volunteers look for fish experiencing Urban Runoff Mortality Syndrome, or URMS, which is characterized by disorientation, loss of swimming ability, a gaping or gasping at the surface of the water. These symptoms indicate that coho salmon have recently encountered toxic stormwater containing 6PPD-Q. Volunteers also look for salmon that died before they could spawn.
Soundkeeper volunteers counted 16 out of 33 dead female coho that had likely died of URMS and had not released their eggs, a 48.5% URMS rate. Read more of our 2023 Survey results here.
You can view our results in a storymap format by clicking here.