For years, something strange was happening in the Pacific Northwest: migrating coho salmon were dying in large quantities. However, only in the last few years have researchers and biologists begun to understand what was happening. They determined that chemical pollution from tires–6PPD-quinone, specifically–was entering streams and killing these salmon and harming other aquatic life. Earlier this month, the Yurok Tribe, the Port Gamble S’Klallam Tribe, and the Puyallup Tribe of Indians (through the organization Earthjustice) petitioned the EPA to officially ban the use of the 6PPD chemical.

How do Tires Harm Salmon?

  •  “Urban runoff mortality syndrome (URMS) occurs annually among adult coho salmon returning to spawn…In the most urbanized watersheds with extensive impervious surfaces, 40 to 90% of returning salmon may die before spawning.” (A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon)
  • ~40% of the Puget Sound’s salmonid habitats are compromised by this pollution.
  • 6PPD has been used in tire manufacturing for decades, but its impact as a potent pollutant is a relatively recent development.
  • As tires wear and degrade, the chemical leaches onto roadways. Then after rain and runoff events, 6PPD is washed into waterways, where we now understand it to have devastating effects on wildlife, coho salmon, specifically.
  • As part of the above study, researchers found that pollution from tires was acutely and rapidly (~2 to 6 hours) lethal to juvenile coho (24 hours exposures, 98.5% mortality, n = 135).
  • 6PPD-q is the second most toxic chemical to aquatic species ever evaluated by EPA.
The Stormwater Heatmap provides a clear picture of stormwater pollution across the Puget Sound. TNC-Washington

The EPA now has 90 days to respond to this petition. While urban waterways will always be subject to heightened runoff pollution, more so than undeveloped areas, this is troubling and deserves a lot of attention. We’ll see what happens with the petition, but our society is not just going to stop using tires anytime soon. So, let’s hope that tire manufactures can start innovating a cleaner, safer alternative to 6PPD, and maybe this petition can incentivize that action! Our fisheries face so many issues and threats–we all need to work together to make things better for the near-term AND the long-term.

Cover picture by Dr. Katherine Peter,  University Washington Tacoma, Center for Urban Waters.


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Will Poston
Will Poston has been with us here at Flylords since 2017 and is now our Conservation Editor. Will focuses on high-profile conservation issues, such as Pebble Mine, the Clean Water Act rollbacks, recovering the Pacific Northwest’s salmon and steelhead, and everything in-between. Will is from Washington, DC, and you can find him fishing on the tidal Potomac River in Washington, DC or chasing striped bass and Albies up and down the East Coast—and you know, anywhere else he can find a good bite!


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