Commenting open: January 20, 2026 12:00AM PT - March 03, 2026 11:59PM PT.
Chapter 173-424 WAC, Clean Fuels Program Rulemaking Informal Comment Period
The Washington State Department of Ecology (Ecology) is beginning a new rulemaking to update the Clean Fuel Standard by implementing Second Substitute House Bill 1409 (SSHB 1409), which was signed into law on May 17, 2025. The rulemaking will amend Chapter 173-424 WAC, Clean Fuels Program Rule and Section 150 of Chapter 173-455 WAC, clean fuels program fees.
Decarbonizing transportation — Washington’s top source of greenhouse gas emissions — is essential to the state’s climate strategy. The Clean Fuel Standard reduces emissions by driving investment in low-carbon transportation fuels, such as renewable diesel, ethanol and electricity for vehicle charging. This legislation more than doubles the policy’s carbon intensity reduction requirements. Previously, the program required a 20% reduction in transportation fuel emissions by 2038. With these changes, the Clean Fuel Standard will reduce the life cycle greenhouse gas emissions from transportation fuels by 45% below 2017 levels by 2038, with the option to reduce as much as 55% by 2038 if certain conditions are met. The policy is already exceeding expectations, and strengthening it will yield even more emissions reductions.
During this rulemaking Ecology will also update the program’s primary carbon intensity determination tool, the WA-GREET model, to WA-GREET 4.0. This will ensure the use of the most up-to-date scientific methodology and make other technical improvements to support policy implementation, such as aligning with other low carbon fuel programs, as directed by RCW 70A.535.060. This rulemaking will also consider other technical amendments necessary to improve implementation of the rule, the fee structure, and the integrity of the greenhouse gas emissions reductions credited in the program.
We invite you to submit informal written comments on the scope of this rulemaking. We will use your input to develop our rule language before proposing the rule. We will also use your comments for the Environmental Justice Assessment associated with this rule. During rule development, we plan to hold multiple meetings to provide updates and gather additional feedback. Please visit WAC 173-424-455 - Washington State Department of Ecology for additional information on this rulemaking.
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The Washington State Department of Ecology (Ecology) is beginning a new rulemaking to update the Clean Fuel Standard by implementing Second Substitute House Bill 1409 (SSHB 1409), which was signed into law on May 17, 2025. The rulemaking will amend Chapter 173-424 WAC, Clean Fuels Program Rule and Section 150 of Chapter 173-455 WAC, clean fuels program fees.
Decarbonizing transportation — Washington’s top source of greenhouse gas emissions — is essential to the state’s climate strategy. The Clean Fuel Standard reduces emissions by driving investment in low-carbon transportation fuels, such as renewable diesel, ethanol and electricity for vehicle charging. This legislation more than doubles the policy’s carbon intensity reduction requirements. Previously, the program required a 20% reduction in transportation fuel emissions by 2038. With these changes, the Clean Fuel Standard will reduce the life cycle greenhouse gas emissions from transportation fuels by 45% below 2017 levels by 2038, with the option to reduce as much as 55% by 2038 if certain conditions are met. The policy is already exceeding expectations, and strengthening it will yield even more emissions reductions.
During this rulemaking Ecology will also update the program’s primary carbon intensity determination tool, the WA-GREET model, to WA-GREET 4.0. This will ensure the use of the most up-to-date scientific methodology and make other technical improvements to support policy implementation, such as aligning with other low carbon fuel programs, as directed by RCW 70A.535.060. This rulemaking will also consider other technical amendments necessary to improve implementation of the rule, the fee structure, and the integrity of the greenhouse gas emissions reductions credited in the program.
We invite you to submit informal written comments on the scope of this rulemaking. We will use your input to develop our rule language before proposing the rule. We will also use your comments for the Environmental Justice Assessment associated with this rule. During rule development, we plan to hold multiple meetings to provide updates and gather additional feedback. Please visit WAC 173-424-455 - Washington State Department of Ecology for additional information on this rulemaking.
Contact Information
*Indicates Required Fields