Draft Regulations Expand Advanced Clean Fleet Regulations

Earlier this month the California Air Resources Board (CARB) released a revised set of amendments to its Advanced Clean Fleets (ACF) regulations. For background the ACF regulations mandate that state and local governments — including counties — transition their medium-duty and heavy-duty vehicle fleets to zero-emission vehicles (ZEV) by 2030. In the revised amendments CARB is seeking to expand the applicability of the ACF regulations to include private fleets that operate under contract with a public agency which could potentially encompass any county contract, regardless of the nature of the work. If CARB adopts the revised language, this would mean that the ACF would apply to a variety of services that county’s contract for, including: 

• Private waste haulers 
• Heavy construction equipment used by contractors on Public Works projects 
• Contract fleets that service county sewer infrastructure 

CSAC, along with a coalition of local government associations, filed formal comments expressing serious concern about the practical and financial impacts of these rules on public agencies.   

Next Steps and Timeline 

The 15-day public comment period on CARB’s second round of ACF amendments closed on June 16, 2026. CARB may now consider further amendments to its ZEV rule before finalizing the regulation. County staff involved in fleet planning, emergency management, or vendor contracting should monitor developments closely. 

A Legislative Response  

A variety of local government and fleet associations believe that CARB’s current proposed changes to the ACF regulations is their attempt to reassert regulatory control over private fleets through their contractual relationships with public agencies.  In response to CARB’s efforts, AB 1436 was recently amended to clarify in state law that CARB cannot regulate private contract fleets, either directly or indirectly, without first securing a federal preemption waiver under the Clean Air Act. We note that CARB withdrew their waiver request to apply the ACF to private fleets from the federal Environmental Protection Agency on January 13, 2025 and it’s unlikely the current federal administration would grant them a waiver. CSAC is part of a broad coalition that is supporting and advocating for AB 1436. 

Mandate Implications 

The ACF regulations have significant mandate implications for counties, particularly public works fleets that are unable to charge user fees to support fleet operations. If CARB successfully updates the ACF regulations to apply to private fleets that counties contract with, there would be notable implications for the likelihood of a successful mandate test claim with the Commission on State Mandates. CSAC encourages counties to determine if they have or will soon be incurring fleet costs to implement the ACF regulations that could be part of a test claim before the Commission on State Mandates. We recommend that counties contact Jessica Sankus (jsankus@counties.org) with any questions on potential mandates costs and the claims process.