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Meetings & Hearings

Clean Vehicles Program, Chapter 173-423 WAC

Public hearing — online

Oct. 12, 2022, 1 p.m., online webinar

Ecology is holding a public hearing about the rulemaking for Clean Vehicles Program, Chapter 173-443 WAC.

Ecology is revising two rules: Chapter 173-423 WAC, Clean Vehicles Program and Chapter 173-400 WAC, General Regulations for Air Pollution Sources.

Ecology is directed by the Motor Vehicle Emission Standards law (RCW 70A.30.010) to adopt California vehicle emission standards and maintain consistency with new versions of California’s rules. This rulemaking will update:

  • Chapter 173-423 WAC, Clean Vehicles Program
    • ​Adopt California's Advanced Clean Cars II rule which will ramp up sales of zero emission vehicles (ZEVs) in Washington, starting in model year 2026.
    • Adopt California's Heavy-Duty Engine and Vehicle Omnibus rules, which require cleaner, less-polluting heavy-duty engines.
    • Establish a credit system for ZEV sales in model years 2023 and 2024, before regulatory requirements take effect.
    • Establish a one-time fleet reporting requirement for owners and operators of large vehicle fleets.
  • Chapter 173-400 WAC, General Regulations for Air Pollution Sources
    • Update adoption date of federal rules by amending sections:
      • WAC 173-400-025 – Adoption by reference
      • WAC 173-400-050 – Emission standards for combustion and incineration units
      • WAC 173-400-070 – Emission standards for certain source categories
      • WAC 173-400-115 – Standards of performance for new sources
      • WAC 173-400-720 – Prevention of significant deterioration (PSD). The rule will keep the current definition of "project emissions accounting."

Motor vehicles are the largest source of air pollution in Washington. Transportation contributes about 22 percent of total air pollution and 45 percent of greenhouse gas emissions throughout Washington. Along with cutting greenhouse gases, reducing vehicle emissions will improve air quality and protect public health, especially for people living near a highway or road with a lot of traffic.

Online public hearing (webinar)

  • Register for the webinar to get your access code and password.
  • To hear the webinar better or to call in only, use your phone (instead of the computer) to call 253-215-8782.


  • Presentation
  • Question-and-answer session
  • Public hearing


We write rules to implement and enforce state and federal environmental laws and rules.  Ecology follows a three-phase process for rulemaking:

  1. Announcement and development
  2. Proposal
  3. Adoption

For each phase of the process, we update the rulemaking web page and notify interested parties. We also file notice in the Washington State Register. To learn more about Ecology’s rulemaking process, read the Frequently Asked Questions.

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Oct. 12, 2022, 1 p.m.
Join online
Join by phone:
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Adam Saul
Rulemaking Lead
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Comment period

Clean Vehicles Program, Chapter 173-423 WAC — Proposed rulemaking
Closes: Oct. 19, 2022, 11:59 p.m.
See details

To request ADA accommodation, contact Ecology's ADA Coordinator by email at ecyadacoordinator@ecy.wa.gov, or call 360-407-6831, 711 (relay service), or 877-833-6341 (TTY). More about our accessibility services.