While PHMSA is responsible for developing and publishing pipeline safety regulations, the pipeline safety statutes provide for States to assume intrastate regulatory, inspection, and enforcement responsibilities under an annual certification. If a State has a pipeline safety program certified by PHMSA, a State Agency is responsible for complaince inspections and failure investigations on intrastate pipeline systems, including most gas distribution pipeline systems. As a result, the majority of pipeline mileage is regulated by State Agencies.

PHMSA issues state certifications for pipeline safety oversight separately for gas pipelines/liquefied natural gas facilities, hazardous liquid pipelines, and underground natural gas storage facilities with different levels of certification possible. See Federal and State Authorities for more information.

Click here for an explanation of various Regulated Entities and Facilities subject to pipeline safety regulations.