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Local watershed group finds 6PPD‑quinone in bridge runoff, urges small bridge/road fixes and habitat projects
Summary
The North Coast Watershed Association reported detection of 6PPD‑quinone, a tire‑rubber byproduct toxic to coho salmon, at several stream locations in Clatsop County and outlined mitigation steps, monitoring, and habitat restoration projects funded with federal and other grants.
Graham Clague, executive director of the North Coast Watershed Association, and Kelly (researcher with the association) told the board the group detected 6PPD‑quinone — a toxic transformation product of a tire additive — in multiple stream samples collected after the first rains following dry periods.
"Every single one of those samples that was just run off had 6PPD‑Q in large amounts," Kelly said, summarizing the association’s field results for direct road runoff sampled at bridge outfalls.
Kelly described results from sampling conducted November 2022 through fall 2024 and said the research was funded in part by an EPA grant and analyzed at the Center for Urban Waters at the University of Washington Tacoma. She said the association detected 6PPD‑quinone at these sites: Bear Creek at Old Highway 30 Bridge; the Lewis and Clark River at Fort Clatsop Road Bridge; and the Skipanon River at the Highway 104 Spur/Alternate Highway 101 bridge.
Kelly said research worldwide shows 6PPD‑quinone can be lethal to coho salmon at extremely low concentrations (research cited in the presentation found effects as low as about 4 nanograms per liter). She described the chemical’s estimated half‑life in water at roughly two weeks and noted organic soils and vegetated buffers can retain and reduce the chemical before it reaches streams.
To reduce direct inputs, Kelly recommended small design changes at bridges with direct downspouts, such as routing runoff through short vegetated swales or organic media instead of discharging straight to streams; she suggested the county and ODOT evaluate small modifications when bridges are repaved or repaired. Kelly also proposed short‑term measures like deploying wattles at drain outlets during the critical early‑rain period.
Clague and Kelly also reviewed ongoing and planned watershed projects: a nearly $1 million grant from the (transcripted) "Bridal Marsh Enhancement Board" leveraged against roughly $3,000,000 in Bureau of Reclamation funding to remove legacy hatchery diversion structures on the North Fork (opening an estimated 12 miles of upstream habitat); large‑wood placements and bridge replacements with private partners such as Hampton Lumber; and continuing basin fish monitoring (snorkel and juvenile density surveys) to track outcomes. The association said the removal and engineered fixes will allow hatchery operations to maintain their functions while restoring access and stream health.
The group described work on invasive aquatic plants (purple loosestrife and yellow flag iris) using drone mapping and spatial models under a cooperative agreement with the National Park Service and Inflation Reduction Act funding; mapping is intended to reduce contractor costs and better target treatments using aquatic herbicide where necessary.
Commissioners expressed support. Commissioner Thompson said he would contact ODOT staff to follow up; Commissioner Webb proposed a summer field trip to sites in Clatsop County and invited the association to help plan it.
Clarifying details: detection sites were specified in the presentation; EPA funded sampling with lab analysis by the University of Washington Tacoma; the association recommended routing bridge runoff through vegetated media and cited estimated chemical persistence (water half‑life ~2 weeks; soils months).
