The next SWG 6PPD Subgroup will be on Thursday December 4th, 2025.

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Calendar Invitation

Date: Thursday December 4th, 2025

Time: 10am -12pm

Agenda and Meeting topics:

•  Agenda

• Meeting Notes - TBD

For more information, please contact Julian Carroll, the SWG Coordinator, at julian.carroll@ecy.wa.gov. 

For past meeting agendas and notes, see past meeting materials.

6PPD Subgroup Background
Coho pre-spawn mortality in Puget Sound streams has been the subject of two-plus decades of research including finding in 2015 that bioretention removes the acute toxicity from road runoff. In December 2020, UW Tacoma chemists released their findings that 6PPD-quinone -- a transformation byproduct of 6PPD, a ubiquitous tire preservative -- is the chemical culprit. 

While the search is on for a safe alternative to 6PPD, the region needs to engage stormwater managers, scientists, and engineers in discussions about what is known about the stormwater management needs and options to address tire wear particles and 6PPD-quinone from the tires on currently on our roads. In February 2021, SWG formed a new subgroup to discuss and continue to build on a list of questions and topics of interest around 6PPD and 6PPD-Q. People from nearly every sector of interest participated in the first meeting in April and the subgroup member list has grown to more than 80 individuals. SWG will continue to hear updates from the subgroup at its regular meetings. 

To receive updates:

Join the email list at Ecology's Subscriber Preferences Page to receive subgroup meeting agendas and notes (enter your email address, click to add subscriptions, and navigate to the Water Quality Program list to find SWG-6PPD-SUBGROUP). For more information, contact Julian Carroll at julian.carroll@ecy.wa.gov. 

Top Questions/Themes

1.    How effectively do current stormwater treatment BMPs in addition to bioretention remove 6PPD and 6PPD-quinone?

2.    What is the geographic scope of the problem and where should we focus retrofits?

3.    What are the chemical and physical characteristics of 6PPD-quinone, including fate and transport?

Additional priorities for investigation and updates

1.    What are the sub-lethal effects on other salmonids, and effects on other species?

2.    Besides treatment, how can we reduce transport from roadways to water bodies?

3.    Lab standards and sampling methods