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

Timeline

Announcement phase (CR-101)

Filing date:
Nov. 20, 2024


Announcement documents

Rule development phase

Nov. 20, 2024 - May 2025

Public 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 
10 a.m. – noon

Presentation

 Information session recording

Combined Community Forum

Wednesday, Jan. 29, 2025 
5 p.m.

Presentation Community forum recording

Industry Focused Public Meeting

Thursday, Jan. 30, 2025
9 a.m. 

Presentation Meeting recording

Public Information Session

Monday, Feb. 3, 2025
9 a.m.

Presentation Session recording

Rule proposal phase (CR-102)

Filing date:
May 15, 2025

Rule proposal documents:

Comment period

You're invited to comment on the rulemaking documents from May 15, 2025 at 12 a.m. to July 3, 2025, at 11:59 p.m. 

Submit comments online. Any information (e.g., personal or contact) you provide in a comment or in an attachment may be publicly disclosed and posted on the internet. 

Attend an online public hearing June 24, 2025, at 9 a.m. or June 25, 2025, at 5 p.m. Please see the Zoom registration links below. 

Mail comments to: 
Nikki Harris 
Washington Department of Ecology
Climate Pollution Reduction Program 
PO Box 47600
Olympia, WA 98504-7600 

Attend a public hearing. We’re hosting public hearings to share information about the proposed rule, answer attendees’ questions, and record testimony.

The public hearings are online (webinar) only, and you can attend from any computer or phone using internet access. Please contact Nikki Harris (Nikki.Harris@ecy.wa.gov) as soon as possible to request interpretation services.

The hearings begin with a short presentation and question-and-answer session, followed by the opportunity to provide testimony. The hearings conclude once attendees who want to provide testimony have had the opportunity to do so. Written comments receive the same consideration as verbal testimony. 

Additional languages

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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.