On June 30, 2025, the U.S. Department of Transportation (DOT) issued DOT Order 5610.1D, DOT's Procedures for Considering Environmental Impacts, which includes PHMSA-specific guidance (Subpart E). These procedures were issued in coordination with the White House Council on Environmental Quality (CEQ) to simplify the environmental review and permitting process and to ensure efficient and timely environmental reviews. The PHMSA-specific procedures establish policies, responsibilities, and procedures to consider the environmental effects of their proposed actions in their decision-making processes and inform and engage the public in that process as required by NEPA (42 U.S.C. §§ 4321-4335).

PHMSA has developed five categorical exclusions, which are listed in Subpart E. Under NEPA and DOT Order 5610.1D, Categorical Exclusions (CEs) are categories of actions that the agency has determined normally do not have a significant effect on the human environment—in their agency NEPA procedures. Once established, an agency determines whether a CE covers a proposed action, and if so, whether there are extraordinary circumstances in which a normally excluded action may have a significant effect. If no extraordinary circumstances are present, the agency may apply the CE to the proposed action. If extraordinary circumstances are present, the agency nevertheless may still categorically exclude the proposed action if it determines there are circumstances that lessen the impacts or other conditions sufficient to avoid significant effects. Subpart E, as well as documentation for PHMSA's CEs are listed below.