Chapter 173-423 WAC – Clean Vehicles Program
Ecology is proposing amendments to our Clean Vehicles Program Rules (Chapter 173-423 WAC) to incorporate changes to the Advanced Clean Trucks and Heavy-Duty Low NOx Omnibus regulations adopted by the California Air Resources Board (CARB), in accordance with RCW 70A.30.010.
This statute states that Ecology shall adopt rules to implement the motor vehicle emission standards of the state of California, including the zero emission vehicle program, and shall amend the rules from time to time, to maintain consistency with the California motor vehicle emission standards. These regulations are an essential policy tool for addressing climate change and improving air quality in Washington.
These amendments respond to industry concerns by easing compliance requirements for the heaviest vehicles. They also streamline implementation and maintain consistency with state and federal laws. The Advanced Clean Trucks program applies to medium- and heavy-duty engine and vehicle manufacturers. It requires manufacturers to gradually sell more new zero-emission models in Washington through model year 2035, and provides flexibility by allowing manufacturers to purchase credits from other manufacturers to meet this requirement and choose which models to transition to zero-emissions technology.
The Heavy-Duty Low NOx Omnibus regulation applies to heavy-duty internal combustion engine manufacturers and requires them to meet more protective air quality standards, particularly on oxides of nitrogen and particulate matter, starting in model year 2026.
Rulemaking timeline
Announcement phase (CR-101)
Filing date:
Nov. 20, 2024
Announcement documents
Rule development phase
Nov. 20, 2024 - May 2025Public input & involvement
Ecology's public meetings
Public comment period (informal)
Dec. 2, 2024, midnight – Feb. 9, 2024, 11:59 p.m.
Read the comments on the Clean Vehicles Program rulemaking.
| Date | Documents | Location |
|---|---|---|
|
Public Information Session Tuesday, Dec. 10, 2024 |
Presentation | |
|
Combined Community Forum Wednesday, Jan. 29, 2025 |
Presentation | Community forum recording |
|
Industry Focused Public Meeting Thursday, Jan. 30, 2025 |
Presentation | Meeting recording |
|
Public Information Session Monday, Feb. 3, 2025 |
Presentation | Session recording |
Rule proposal phase (CR-102)
May 15, 2025
- Proposal notice (CR-102 form)
- Proposed rule language
- SEPA Determination of Non-significance and Environmental Checklist
Comment period
The comment period closed July 3, 2025, at 11:59 p.m. Please see submitted comments here.
Public hearings for this rulemaking were held on June 24, 2025, at 9 a.m. and June 25, 2025, at 5 p.m. Please see recordings and presentation materials below.
The hearings began with a short presentation and question-and-answer session, followed by the opportunity to provide testimony. Written comments receive the same consideration as verbal testimony.
Accessibility
To request ADA accommodation for disabilities, or printed materials in a format for the visually impaired, contact Ecology's ADA Coordinator by email at ecyadacoordinator@ecy.wa.gov, or call 360-407-6831. People with impaired hearing may call Washington Relay Service at 711. People with speech disability may call TTY at 877-833-6341.