Washington Proposes New Carbon Reduction Trajectories for State’s Clean Fuel Standard
The Washington State Department of Ecology (Ecology) outlined potential updates late Tuesday to the state’s Clean Fuel Standard (CFS) carbon intensity reduction schedule for 2028 through 2038 and the agency is seeking public comment on the changes, which aim to align the schedule with recently enacted state legislation.
Adopted in May 2025, Washington’s House Bill (HB) 1409 amended the existing carbon intensity standard for the CFS and advanced a schedule to reduce the carbon intensity of transportation fuels in the state to 45% below 2017 levels by 2038. HB-1409 required target adjustments to begin in January 2026 and add onto the reduction targets that were previously adopted when Ecology established the Washington State CFS in 2023.
Through this active rulemaking, Ecology will set the annual CI reduction targets for 2028 through 2038. The annual reduction increases will range from a 3% minimum to a 4% maximum to achieve a cumulative 45% CI reduction by 2038. The regulatory framework established via HB-1409 grants Ecology the flexibility to determine the exact annual percentage within that range and also authorizes the state agency to conditionally increase the total greenhouse gas emissions reduction requirement to 55% by 2038, which would require updates to the annual targets via further rulemaking.
Ecology is analyzing and seeking public input on three closely aligned scenarios that each yield an identical 45% cumulative CI reduction result by 2038, despite subtle differences in their annual reduction trajectories. Scenario A represents the least gradual approach with an initial 4% reduction in 2028 followed by 3% annual decreases in subsequent years, while Scenarios B and C phase the targets incrementally by starting with 3.5% reductions for 2028 to 2029 and 3.25% reductions for 2028 to 2031, respectively.
The state agency also published feedback received from the public comment period that ran from Ecology’s initial announcement of the proposed rulemaking on Jan. 20, 2026 through March 2026. Several stakeholders recommended that Ecology implement both the maximum 4% annual reduction and the 55% cumulative reduction target to signal market support for low-carbon fuels.
Ecology’s official rule proposal is expected to be formally filed in spring 2027. The deadline for comments submitted to the agency on the proposed rulemaking and three CI reduction modeling scenarios is Sept. 30.
Reporting by Maura Hossler, mhossler@opisnet.com ; Editing by Jordan Godwin, jgodwin@opisnet.com