Chapter 173-424 WAC – Clean Fuels Program
On October 20, 2025, we adopted amendments to Chapter 173-424 WAC (Clean Fuels Program Rule). The rule aims to reduce the carbon emissions from transportation fuels used in Washington.
Many of the adopted changes support greenhouse gas emissions reductions in “hard-to-decarbonize” sectors, such as aviation and heavy-duty trucking. Other major changes included the creation of a third-party verification program and amended crediting procedures for electricity and renewable natural gas. Edits were adopted based on experiences from the program’s first two years of implementation, best practices used in other states, and input from interested parties expressed through public comments, meetings with Ecology staff, informal workshops, and other engagement opportunities. Read the full list of changes adopted by Ecology.
Ecology plans to soon announce new rulemaking to incorporate changes to the Clean Fuel Standard set by House Bill 1409, which was passed in the 2025 legislative session and strengthens the program’s carbon intensity requirements.
Rulemaking timeline
Announcement phase (CR-101)
Filing date:
Dec. 18, 2023
Announcement documents
Rule development phase
Dec. 18, 2023 – Fall 2024Public input & involvement
Draft rule language
Below are the most updated drafts of the rule language, released Nov. 26, 2024:
- November 2024 CFS draft rule language
- November 2024 rule changes summary (updated Dec. 4, 2024, with corrections)
The following links contain the initial draft rule updates, released Aug. 29, 2024:
Fourth public comment period (informal)
Nov. 26, 2024 – Dec. 13, 2024
Third public comment period (informal)
Aug. 29, 2024 – Oct. 3, 2024
Second public comment period
April 25, 2024 – June 7, 2024
First public comment period (informal)
Feb. 15, 2024 – March 24, 2024
Ecology's public meetings
| Date | Documents | Location |
|---|---|---|
| Thursday Feb. 22, 2024 1 p.m. – 3 p.m. |
||
| Wednesday Feb. 28, 2024 1 p.m. – 3 p.m. |
Agenda Presentation |
Webinar recording 1 |
| Thursday May 2, 2024 1 p.m. – 3 p.m. |
Presentation | Webinar recording 1 |
| Wednesday May 8, 2024 10 a.m. – noon |
Presentation | Webinar recording 1 |
|
Wednesday |
Presentation | Listening session recording |
|
Monday |
Presentation | Webinar recording |
| Tuesday Sept. 12, 2024 10 a.m. – noon |
Presentation | Webinar recording |
| Thursday Sept. 26, 2024 1 p.m. – 3 p.m. |
Presentation | Webinar recording |
| Thursday Dec. 5, 2024 2 p.m. – 4 p.m. |
Presentation | Webinar recording |
| Wednesday Dec. 11, 2024 10 a.m. – noon |
Presentation | Webinar recording* |
* Ecology inadvertently began recording this webinar late and missed the opening slides of the presentation. The Dec. 5, 2024, recording linked above covers the same content and includes full information on the rulemaking timeline and updates to avoided methane crediting.
1 Webinar information:
Register for each webinar to get your meeting ID and passcode.
To hear the webinar better or to call in only, use your phone (instead of the computer) to call 253‑215‑8782.
Rule proposal phase (CR-102)
June 16, 2025
- Proposal Notice - CR-102 form
- Proposed rule language (173-424 WAC)
- Preliminary Regulatory Analysis
- SEPA Determination of Non-significance (DNS) and Environmental Checklist
Comment period
Comments were due by August 1, 2025, 11:59 PM.
Comment period: June 16, 2025 at 12am – August 1, 2025 at 11:59pm
Ecology will review and consider all the comments received before rule adoption later this year. See above for documents related to the Proposal Phase of the rulemaking.
We accepted comments in the following ways:
- Read comments submitted online
- Mail to:
For standard US Mail-
Department of Ecology
Climate Pollution Reduction Program
Adam Saul
PO BOX 47600
Olympia, WA 98504-7600
For Parcel Service-
Department of Ecology
Climate Pollution Reduction Program
Adam Saul
300 Desmond Dr SE
Lacey, WA 98503 - Attend a public hearing - see below
The hearings included a short presentation and question and answer session, followed by the opportunity to provide testimony.
Full list of changes
- Updated requirements regarding the production of low-carbon intensity alternative jet fuel, in alignment with Engrossed Substitute Senate Bill 5447 (Chapter 232, Laws of 2023).
- New requirements for electrolysis energy used in the production of alternative jet fuel and alternative marine fuel.
- Third-party verification requirements to improve the accuracy of information used to generate credits and deficits in the program.
- Amended requirements for the use of indirect (“book-and-claim”) accounting of low-carbon intensity biomethane or electricity. This accounting method allows fuel producers to use indirectly supplied renewable electricity or biomethane to lower the carbon intensities of fuels they report in the program, subject to certain conditions specified in rule. The amendments aim to encourage in-state and regional renewable energy production and maximize local environmental benefits.
- Updated requirements to “avoided methane crediting”, which grants fuel producers additional credits for voluntarily capturing methane from dairy and swine manure and organic waste diverted from landfills. To maximize short-term climate pollution reduction benefits, the highest incentives will be granted to new methane capture projects that begin initial construction on or before December 31, 2029. The adopted rule also adds safeguards intended to mitigate the risk of negative environmental and public health externalities occurring from these incentives.
- Amended requirements related to capacity credits for zero emission vehicle infrastructure, including expanding credit generation opportunities to electric charging and hydrogen refueling sites shared by multiple heavy-duty vehicle fleets.
- Updated requirements to harmonize the rule with policies in California and Oregon’s low-carbon fuels programs.
- Amendments to improve clarity and readability, correct errors, and streamline reporting and registration requirements.
Rule adoption phase (CR-103)
Oct. 20, 2025
Nov. 20, 2025
Related links
Contact information
Adam Saul
Environmental Planner
adam.saul@ecy.wa.gov
360-742-7998
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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.