For several decades, many coho salmon returning to waterways around Seattle to spawn have died mysteriously following heavy rains. In some urban streams, nearly all of the coho returning from the ocean died.  It wasn’t until 2021 that scientists figured out what was behind what they called “urban runoff mortality syndrome,” and it was not until this month that federal regulators at the Environmental Protection Agency moved to do something about it. The EPA on Nov. 2 said it would consider an August petition from the California-based Yurok Tribe and the Washington-based Port Gamble S’Klallam and Puyallup tribes, calling for a ban of the chemical 6PPD-q. It’s used in car tires to keep them from cracking and degrading, but as tires wear down, they shed particles containing the chemical into stormwater and streams.

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