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Puget Sound toxic pollution

In Puget Sound, 45 percent of river systems show levels of toxic chemical pollution that increase health risks to juvenile Chinook salmon. As they grow, Puget Sound Chinook salmon accumulate toxic chemicals, which poses health risks to predators, including southern resident orca whales. Most toxic pollution in the Puget Sound is carried by stormwater that runs off paved roads and driveways, rooftops, yards, and other developed land. These contaminants can reduce growth, increase disease susceptibility, and alter hormone production, all of which can reduce survival of fish. The greatest risks occurred in three highly developed watersheds–the Duwamish River, Hylebos/Puyallup, and Snohomish systems.

Stream flows in Puget Sound are in flux

When there is less rain and warmer temperatures in the summer, some of the streams have less water. Low water levels can reduce the amount of habitat, food, and water quality for fish. In Puget Sound, low water levels in the summer have remained consistent with the regional target or have improved. Although stream flows have improved over the long-term, they have improved only slightly in the past several years.

Indicator data

Water Quality

What does this indicator mean?


Geographical Representation of Caution For Contaminants in Juvenile Chinook Salmon

The chart below shows levels of polychlorinated biphenyls (PCBs), which are chemicals used in various industries and which were banned in the United States in 1979, and polybrominated diphenylethers, (PBDEs), which were used as flame-retardants in many products and which were banned in 2011 in Washington State.


Water Quantity


Visit How we measure for background about this data, and our Salmon Data Portal for original source data behind the indicator charts and graphs used throughout this site.