Washington bans 6PPD in tires — coho salmon mortality driver phased out by 2035. Governor Ferguson signed HB 2421 on March 14, 2026, making Washington the first state to ban 6PPD, a tire rubber additive whose transformation product (6PPD-quinone) causes acute pre-spawn mortality in coho salmon. The ban takes effect in 2035. Research has documented pre-spawn mortality as high as 40% in Puget Sound urban streams exposed to stormwater runoff carrying the compound.
What this means for restoration portfolios. The 2035 timeline means this does not change near-term obligations. It does change the ecological baseline that restoration investments are designed around: entities funding urban stream restoration in Puget Sound are currently investing in habitat where a known lethal contaminant will persist for another decade. The ban establishes a future inflection point — restoration work that looks structurally marginal today may become viable once the contaminant source is removed.
Source: HB 2421, signed March 14, 2026; Puget Sound Institute
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