Freshwater habitat

The search for why large numbers of spawning coho salmon have been dying in Puget Sound's urban streams goes as far back as the 1980s and culminated this year with the discovery of a previously unidentified chemical related to automobile tires. We offer a detailed timeline for the discovery. 

Environmental engineers and chemists at the University of Washington Tacoma have identified a mysterious compound implicated in the deaths of large numbers of coho salmon in Puget Sound. The chemical is linked with a rubber additive commonly used in tires and is thought to kill more than half of the spawning coho that enter the region's urban streams every year. 

Many creeks and waterbodies in Puget Sound may look pristine, but most face serious threats from stormwater pollution. A new study at Soos Creek shows how mud-dwelling bugs, traditional chemistry and digital "heatmaps" can be used to track stormwater impacts and identify the most polluted areas. Scientists and planners hope that this may one day lower the price tag on costly stormwater fixes. 

The Nooksack River watershed spans part of the border between British Columbia and the State of Washington. In August 2018, the international, multi-agency Nooksack River Transboundary Technical Collaboration Group (TCG) was established to implement a three-year work plan to reduce fecal bacteria concentrations in the Nooksack River watershed. This 2019-2020 TCG annual report summarizes second year project activities and focuses on three of the watershed's transborder sub-basins.

Climate models project that if carbon emmisions continue as they are now, the vast majority of watersheds feeding Puget Sound will receive more rain and far less snow by 2080, causing increased flooding and other dramatic changes to the freshwater ecosystem. We look at the past and possible future of the region's snowpack and what this might mean for salmon and other species — including humans.

High levels of mercury and other toxic chemicals are showing up in seemingly remote and pristine parts of the Puget Sound watershed, the result of atmospheric deposition. Scientists talk about a “dome” of pollution hanging over urban areas, leading to a never-ending cycle of persistent compounds working their way through the air, onto the land and into the water.