Contents

• Introduction
• The U.S. Pipeline Network
• Safety in the Pipeline Industry
• PHMSA's Pipeline Safety Program
• Pipeline and Hazardous Materials Safety Administration
• Organization and Funding
• Regulatory Activities
• Regulation of Offshore Pipelines
• Pipeline Safety Enforcement
• Reauthorization and Pipeline Safety Statutes
• Cooperation with FERC
• PHMSA and the NTSB
• PHMSA's Role in Pipeline Security
• DOT's Early Role in Pipeline Security
• PHMSA Cooperation with TSA
• Clarifying PHMSA and TSA Security Roles
• Colonial Pipeline Incident
• Policy Issues for Congress
• Staffing Resources for Pipeline Safety
• Aging Pipeline Modernization
• Gathering Line Regulation
• PHMSA Regulation of Methane Leaks and Emissions
• PHMSA and Pipeline Security
• Carbon Dioxide Pipeline Rulemaking
• Hydrogen Pipeline Safety
• Special Permits
• Outdated LNG Safety Standards
• Class Location Requirements
• Pipeline Safety Research, Development, and Demonstration
• Pipeline Repair Criteria
• Conclusion

Summary

The U.S. energy pipeline network includes 3.3 million miles of onshore pipeline transporting natural gas, crude oil, and other hazardous liquids. Over the past decade, major safety incidents in California, Texas, Pennsylvania, and other states have drawn criticism from stakeholders and have raised concerns in Congress about pipeline safety regulation. The 2021 ransomware attack on the Colonial Pipeline has also drawn attention to federal pipeline security activities, including agency roles and the linkage between pipeline safety and security.

The federal safety program for onshore pipelines is administered by the Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA), which relies heavily on state partnerships for inspection and enforcement. PHMSA's pipeline safety program was authorized through FY2023 under the Protecting Our Infrastructure of Pipelines and Enhancing Safety Act of 2020 (PIPES Act; P.L. 116-260, Div. R). Although this authorization has expired, Congress has appropriated funds for PHMSA's continued operation. The Infrastructure Investment and Jobs Act (IIJA; P.L. 117-58) appropriated $200 million annually through FY2026 for PHMSA's Natural Gas Distribution Infrastructure Safety and Modernization Grant Program.

To promote regulatory compliance, PHMSA conducts programmatic inspections of management systems and procedures; inspects facilities and construction; investigates safety incidents; and maintains a dialogue with pipeline operators. The agency clarifies its expectations through orders, guidance manuals, and public meetings. It also administers a pipeline safety research and development (R&D) program to address emerging risks and new technologies. PHMSA works with the Transportation Security Administration (TSA) on pipeline security and incident response.

As Congress considers reauthorizing PHMSA's pipeline safety program, Congress may examine PHMSA staffing, which faces persistent shortfalls affecting the agency's ability to conduct inspections and revise regulations. Other potential topics of congressional interest could include

• the implementation of PHMSA's distribution modernization grant program;
• the effects of the agency's 2021 rule for natural gas gathering lines, bringing 425,000 miles of gathering lines under regulation;
• PHMSA's implementation of the PIPES Act mandate regarding its regulation of methane leaks and emissions;
• what role PHMSA might play in any future TSA pipeline security initiatives;
• updates to safety standards for liquefied natural gas facilities; for pipelines carrying carbon dioxide, hydrogen, or hydrogen-methane blends; for gas pipeline class location changes; and for pipeline repair criteria;
• PHMSA's issuance and oversight of standards exemptions via special permits; and
• PHMSA's implementation and coordination of pipeline safety R&D through its own grants, operator demonstrations, and programs at other federal agencies.

In addition to these issues, Congress may assess how the many elements of U.S. pipeline safety fit together in the nation's overall approach to protecting the public and the environment. Pipeline safety necessarily involves various groups: federal and state agencies, tribal governments, pipeline associations, large and small pipeline operators, local communities, and other interest groups. Reviewing how these groups work together to achieve common goals or resolve conflicting approaches could be an overarching concern for Congress.

Introduction

The U.S. energy pipeline network is integral to the nation's energy supply and provides vital links to other critical infrastructure, such as power plants, airports, and military bases. These pipelines are geographically widespread, running alternately through remote and densely populated regions—from Arctic Alaska to Florida and nearly everywhere in between (Figure 1). Because energy pipelines carry volatile, flammable, or toxic materials, they have the potential to injure the public, destroy property, and harm the environment. Although they are considered an efficient and comparatively safe means of transport, pipeline systems are also vulnerable to accidents, operational failure, and malicious attacks. Recent major incidents in California, Texas, and Pennsylvania, among other places, have demonstrated the risks of pipeline failure and have heightened congressional concern about U.S. pipeline safety. A 2021 cyberattack on the Colonial Pipeline likewise demonstrated the economic impacts of a major pipeline disruption and put a focus on the linkage between pipeline safety and security.

Figure 1. U.S. Natural Gas Transmission and Hazardous Liquid Pipelines

Source: National Pipeline Mapping System (NPMS), March 2025, https://www.npms.phmsa.dot.gov/Documents/NPMS_Pipelines_Map.pdf. Notes: Map does not show gas distribution or gas gathering pipelines. Hazardous liquids primarily include crude oil, gasoline, jet fuel, diesel fuel, home heating oil, propane, and butane. Other hazardous materials transported by pipeline and regulated as liquids include anhydrous ammonia, carbon dioxide, kerosene, liquefied ethylene, and petrochemical feedstock.

The federal safety program for onshore pipelines resides primarily within the Department of Transportation's (DOT's) Pipeline and Hazardous Materials Safety Administration (PHMSA), although its inspection and enforcement activities rely heavily upon partnerships with the states. Together, the federal and state pipeline safety agencies administer a comprehensive set of regulatory authorities that continues to evolve. DOT's pipeline safety program was authorized through the fiscal year ending September 30, 2023, under the Protecting Our Infrastructure of Pipelines and Enhancing Safety Act of 2020 (PIPES Act; P.L. 116-260, Div. R) signed by President Trump on December 27, 2020. Although this authorization has expired, Congress has appropriated funds for PHMSA's continued operation.

This report reviews the history and role of the federal program for pipeline safety, including a discussion of pipeline safety trends and major accidents. It discusses significant regulatory changes in reauthorization statutes and summarizes ongoing developments in key policy areas. It discusses PHMSA's relationship with other federal agencies involved in pipeline safety. Although pipeline security is not mainly under PHMSA's jurisdiction, the report examines the agency's role in pipeline security and its recent work on security-related issues with other agencies.

The U.S. Pipeline Network

The onshore U.S. energy pipeline network is composed of 3.3 million miles of pipeline transporting natural gas, oil, and other hazardous liquids (Table 1). Of the nation's approximately half-million miles of long-distance transmission pipeline, roughly 230,000 miles carry hazardous liquids—over 83% of the nation's crude oil and refined products—along with carbon dioxide (CO₂) and other products.¹ The U.S. natural gas pipeline network consists of around 300,000 miles of transmission and 380,000 miles of gathering lines. The natural gas transmission pipelines feed around 2.4 million miles of regional pipeline mains and service lines in some 1,300 local distribution networks serving over 72 million customers.² A relatively small network of dedicated hydrogen pipelines, with around 1,600 total miles of pipe, is also in operation.

Natural gas pipelines also connect to 176 active liquefied natural gas (LNG) storage sites, as well as underground storage facilities, both of which can augment pipeline gas supplies during peak demand periods.³

Safety in the Pipeline Industry

Uncontrolled pipeline releases can result from a variety of causes, including third-party excavation, corrosion, mechanical failure, control system failure, operator error, and malicious acts. Natural forces, such as floods and earthquakes, can also damage pipelines. Taken as a whole, releases from pipelines cause few annual injuries or fatalities compared to other product transportation modes.⁴ According to PHMSA statistics, there were, on average, 11 deaths and 48 injuries caused by 26 pipeline incidents annually in all U.S. pipeline systems from 2014 through 2024.⁵ During this period, the yearly incident count has fluctuated, with no clear trend (Figure 2). A total of 25 serious pipeline incidents was reported for 2024.

Figure 2. Pipeline Incidents Causing Injuries or Fatalities, 2014-2024 (Annual "Serious" Incidents)

Source: PHMSA, "Pipeline Incident 20 Year Trends," online database, accessed April 9, 2025, https://www.phmsa.dot.gov/data-and-statistics/pipeline/pipeline-incident-20-year-trends. Note: PHMSA defines "serious" incidents as those causing a fatality or injury requiring inpatient hospitalization.

Apart from injury to people, some accidents may cause local environmental damage or other physical impacts, which may be significant, particularly in the case of oil spills or fires. PHMSA requires the reporting of such incidents involving

• $50,000 or more in total costs, measured in 1984 dollars;
• highly volatile liquid releases of 5 barrels or more or other liquid releases of 50 barrels or more; or
• liquid releases resulting in an unintentional fire or explosion.⁶

On average there were 265 such "significant" incidents (those not involving injury or fatality) per year from 2014 through 2024. The average significant incident count has fluctuated since 2014, with a declining overall trend (Figure 3). A total of 235 significant pipeline incidents were reported for 2024. It should be noted that federally regulated pipeline mileage overall rose approximately 8% over this period; neither the annual statistics for injury nor environmental incidents are adjusted on a per-mile basis.⁷

Figure 3. Pipeline Incidents Causing Environmental or Property Damage, 2014-2024 (Annual "Significant" Incidents)

Source: PHMSA, "Pipeline Incident 20 Year Trends," online database, accessed April 9, 2025, https://www.phmsa.dot.gov/data-and-statistics/pipeline/pipeline-incident-20-year-trends. Notes: Includes "significant" incidents, with $50,000 or more in total costs (1984 dollars), highly volatile liquid releases of 5 barrels or more or other liquid releases of 50 barrels or more, or liquid releases resulting in an unintentional fire or explosion. Excludes incidents causing a fatality or injury requiring inpatient hospitalization; these are categorized as "serious" incidents (see Figure 2).

Although pipeline releases have caused relatively few fatalities in absolute numbers, a single pipeline accident can be catastrophic in terms of public safety and environmental damage. For example, in 2015, the Aliso Canyon Underground Storage Facility near the Porter Ranch community in Los Angeles County, CA, began experiencing an uncontrolled natural gas leak that ultimately released an estimated 5.4 billion cubic feet of natural gas, an asphyxiant and a potent greenhouse gas (GHG).⁸ The risk to safety from the fugitive methane and the presence of odorants and other chemicals in the gas led to the temporary relocation of over 8,000 households and two schools in nearby Porter Ranch. In 2018, overpressure in a natural gas distribution main in Merrimack Valley, MA, killed one person, injured 21 others, damaged 131 structures, and caused 30,000 residents to evacuate their homes for several days.⁹ In 2023, a natural gas pipeline-related explosion and fire at a West Reading, PA, candy factory destroyed the factory, killed 7 people, caused 10 other people to be hospitalized, and severely damaged nearby buildings.¹⁰ Such incidents have generated persistent scrutiny of pipeline risks and have increased federal, state, and community activity related to pipeline safety.

PHMSA's Pipeline Safety Program

PHMSA has the primary responsibility for the formulation, administration, and oversight of onshore pipeline safety regulations in the United States. The agency does so through its Office of Pipeline Safety (OPS), whose functions include oversight of pipeline operators, support of state pipeline safety agencies, and cooperation with other federal agencies that have pipeline safety responsibilities. The latter include the Department of the Interior's Bureau of Safety and Environmental Enforcement (BSEE), which regulates offshore oil and natural gas facilities, and the Federal Energy Regulatory Commission (FERC), which has siting authority for interstate natural gas pipelines. PHMSA also cooperates with the National Transportation Safety Board (NTSB), an independent agency that investigates accidents and issues safety recommendations.

Pipeline and Hazardous Materials Safety Administration

The Natural Gas Pipeline Safety Act of 1968 (P.L. 90-481) and the Hazardous Liquid Pipeline Safety Act of 1979 (P.L. 96-129) are the principal acts establishing the federal role in pipeline safety. Under both statutes, the Secretary of Transportation has primary authority to regulate key aspects of pipeline safety: design, construction, operation and maintenance, and spill response planning. Pipeline safety regulations are covered in Title 49 of the Code of Federal Regulations.¹¹

Organization and Funding

As of February 14, 2025, PHMSA's organizational chart listed 326 full-time equivalent (FTE) staff in OPS—including 113 staff listed as "inspectors" and 12 staff listed as "accident investigators."¹² There are also agency positions outside of OPS that support certain pipeline safety functions.¹³ In addition to federal staff, PHMSA's enabling legislation allows the agency to delegate authority to state pipeline safety offices, enabling them to act as "agents" administering pipeline safety programs for intrastate pipelines and allowing them to perform inspections (but not enforcement) of interstate pipeline segments within their boundaries.¹⁴ According to DOT, "States inspect and enforce pipeline safety regulations for over 85 percent of the infrastructure under PHMSA's safety authority."¹⁵ A few states serve as agents for inspection of interstate pipelines as well. There were 444 state inspectors in 2024.¹⁶ PHMSA may reimburse states for up to 80% of their pipeline safety expenditures through State Pipeline Safety Grants. In 2023 (the latest year with published data), actual grant awards to states covered approximately 53% of state expenditures, on average.¹⁷ PHMSA may also fund states through Underground Natural Storage Grants, State Damage Prevention Grants, State One-Call Grants, and Natural Gas Distribution Infrastructure Safety and Modernization Grants, discussed further below.

Figure 4. PHMSA Pipeline Safety Total Annual Budget Authority, 2015-2025 (Millions of Dollars)

Source: U.S. Office of Management and Budget, Budget of the United States Government, Appendix, Fiscal Years 2015 through 2023, "Pipeline Safety," Line 1900 "Budget authority (total)"; Consolidated Appropriations Act, 2024 (P.L. 118-42); Full-Year Continuing Appropriations and Extensions Act, 2025 (P.L. 119-4). Notes: Column values are "actual" budget authority totals except for 2024, which is "estimated," and 2025, which is based on funding as provided under a continuing resolution. Values are not adjusted for inflation.

PHMSA's pipeline safety program is funded primarily by user fees assessed on a per-mile basis on each regulated pipeline operator.¹⁸ The agency's total annual budget authority has grown over the last decade (Figure 4). PHMSA's pipeline safety budget in FY2025 is approximately $218 million, roughly $73 million more than the FY2023 budget authority (in nominal dollars).

Regulatory Activities

PHMSA uses a variety of strategies to promote compliance with its safety standards. The agency conducts programmatic inspections of management systems, procedures, and processes; conducts physical inspections of facilities and construction projects; investigates safety incidents; and maintains a dialogue with pipeline operators. The agency clarifies its regulatory expectations through published protocols and regulatory orders, guidance manuals, and public meetings.

In 1997, PHMSA began requiring industry to implement "integrity management" programs on pipeline segments near "high consequence areas" (HCAs). Integrity management provides for continual evaluation of pipeline condition, assessment of risks to the pipeline, inspection or testing, data analysis, and follow-up repair as well as preventive or mitigative actions. High consequence areas include population centers, commercially navigable waters, and environmentally sensitive areas, such as drinking water supplies or ecological reserves. The integrity management approach is intended to prioritize resources to locations of highest consequence rather than applying uniform treatment to the entire pipeline network. PHMSA made integrity management programs mandatory for most oil pipeline operators with 500 or more miles of regulated pipeline as of March 31, 2001 (49 C.F.R. §195). Congress subsequently mandated the expansion of integrity management to natural gas pipelines and has continued to make other significant changes to federal pipeline safety requirements through PHMSA budget reauthorizations, as discussed below.

Regulation of Offshore Pipelines

Offshore pipelines are regulated primarily by BSEE, which is responsible for the safety and environmental oversight of oil and gas operations, as well as oil spill response on the Outer Continental Shelf.¹⁹ PHMSA shares with BSEE oversight of certain offshore pipeline facilities. Under the terms of a December 2020 Memorandum of Understanding (MOU) between the two agencies, PHMSA is responsible for "all OCS pipelines beginning downstream of the point at which operating responsibility transfers from a producing operator to a transporting operator, or downstream of the last valve on the last production facility on the OCS for pipelines that cross into State waters."²⁰ In addition, BSEE regulations allow a producer to petition to have its pipeline operate under PHMSA regulations for pipeline design, construction, operation, and maintenance.²¹ Likewise, a transporter who operates a PHMSA-regulated pipeline may petition to operate under BSEE regulations for pipeline operation and maintenance.²² Policy issues related primarily to BSEE or to pipelines under its jurisdiction are outside the scope of this report.

Pipeline Safety Enforcement

PHMSA relies upon a range of enforcement actions, including administrative actions such as safety orders and civil penalties, to try to ensure that operators correct safety violations and take measures to preclude future safety problems. From 2020 through 2024, PHMSA initiated 1,081 enforcement actions against pipeline operators.²³ Of these cases, 376 involved notices of probable violation, which allege specific regulatory violations, and 15 involved corrective action orders, which "usually address urgent situations arising out of an accident, spill, or other significant, immediate, or imminent safety or environmental concern."²⁴ Civil penalties proposed by PHMSA for safety violations during this period totaled approximately $44 million.²⁵ PHMSA also conducts accident investigations and system-wide reviews focusing on high-risk operational or procedural problems and areas of the pipeline near sensitive environmental areas, high-density populations, or navigable waters.

Reauthorization and Pipeline Safety Statutes

The PIPES Act was preceded by a periodic series of pipeline safety statutes, each of which reauthorized funding for PHMSA's pipeline safety program and included other provisions related to PHMSA's authorities, administration, or regulatory activities.

Pipeline Safety Improvement Act of 2002

On December 12, 2002, President George W. Bush signed into law the Pipeline Safety Improvement Act of 2002 (P.L. 107-355). The act strengthened federal pipeline safety programs, state oversight of pipeline operators, and public education regarding pipeline safety.²⁶ Among other provisions, P.L. 107-355 required operators of regulated natural gas pipelines in high consequence areas to conduct risk analysis and implement integrity management programs similar to those required for oil pipelines. The act authorized DOT to order safety actions for pipelines with potential safety problems and increased violation penalties. The act streamlined the permitting process for emergency pipeline restoration by establishing an interagency committee—including DOT, the Environmental Protection Agency, the Bureau of Land Management, FERC, and other agencies—to ensure coordinated review and permitting of pipeline repairs. The act required DOT to study ways to limit pipeline safety risks from population encroachment and ways to preserve environmental resources in pipeline rights-of-way. P.L. 107-355 also included provisions for public education, grants for community pipeline safety studies, "whistleblower" and other employee protection, employee qualification programs, and mapping data submission.

Pipeline Inspection, Protection, Enforcement, and Safety Act of 2006

On December 29, 2006, President Bush signed into law the Pipeline Inspection, Protection, Enforcement and Safety Act of 2006 (P.L. 109-468). The main provisions of the act address pipeline damage prevention, integrity management, corrosion control, and enforcement transparency. The act created a national focus on pipeline damage prevention through grants to states for improving damage prevention programs, establishing 811 as the national "call before you dig" one-call telephone number, and giving PHMSA limited "backstop" authority to conduct civil enforcement against one-call violators in states that have failed to conduct such enforcement. The act mandated the promulgation by PHMSA of minimum standards for integrity management programs for natural gas distribution pipelines.²⁷ It also mandated a review of the adequacy of federal pipeline safety regulations related to internal corrosion control and required PHMSA to increase the transparency of enforcement actions by issuing monthly summaries including violation and penalty information and a mechanism for pipeline operators to make response information available to the public.

Pipeline Safety, Regulatory Certainty, and Job Creation Act of 2011

On January 3, 2012, President Obama signed the Pipeline Safety, Regulatory Certainty, and Job Creation Act of 2011 (Pipeline Safety Act; P.L. 112-90). The act contains a broad range of provisions addressing pipeline safety. Among the most significant are provisions to increase the number of federal pipeline safety inspectors, require automatic shutoff valves for transmission pipelines, mandate verification of maximum allowable operating pressure for gas transmission pipelines, increase civil penalties for pipeline safety violations, and mandate reviews of diluted bitumen pipeline regulation. Altogether, the act imposed 42 mandates on PHMSA regarding studies, rules, maps, and other elements of the federal pipeline safety program. P.L. 112-90 authorized the federal pipeline safety program through the fiscal year ending September 30, 2015.

Protecting Our Infrastructure of Pipelines and Enhancing Safety Act of 2016

On June 22, 2016, President Obama signed the Protecting Our Infrastructure of Pipelines and Enhancing Safety Act (PIPES Act) of 2016 (P.L. 114-183). Among other provisions, the act requires PHMSA to promulgate federal safety standards for underground natural gas storage facilities and grants PHMSA emergency order authority to address urgent "industry-wide safety conditions" without prior notice. The act also requires PHMSA to report regularly on the progress of outstanding statutory mandates. The act authorized the federal pipeline safety program through FY2019.

Protecting Our Infrastructure of Pipelines and Enhancing Safety Act of 2020

On December 27, 2020, President Trump signed the PIPES Act of 2020 (P.L. 116-260, Div. R).²⁸ The act authorized the federal pipeline safety program through FY2023. Among its key provisions, the act required PHMSA to review and update its safety standards for large-scale LNG facilities, adopting a risk-based regulatory approach. The act also imposed stricter standards for natural gas pipeline leak detection and repair, requiring repair of all leaks hazardous to human safety or the environment or with the potential to become hazardous. It also mandated new safety requirements for natural gas distribution systems in response to the 2018 Merrimack Valley incident.²⁹ These requirements include updates to distribution integrity management, emergency response plans to address overpressurization risks, and a requirement for PHMSA to report on industry adoption of pipeline safety management systems. The act also included provisions intended to help PHMSA attract and maintain a sufficient workforce of pipeline inspection and enforcement personnel.

In addition to the authorization in the PIPES Act of 2020, the Infrastructure Investment and Jobs Act (IIJA; P.L. 117-58) appropriates annual funding through FY2026 for a new Natural Gas Distribution Infrastructure Safety and Modernization Grant Program administered by PHMSA.³⁰

Cooperation with FERC

One area related to pipeline safety not under PHMSA's primary jurisdiction is the siting approval of interstate natural gas pipelines, which is the responsibility of FERC. Companies building interstate natural gas pipelines must first obtain from FERC certificates of public convenience and necessity. (FERC does not oversee oil pipeline siting or construction.) FERC must also approve the abandonment of gas facility use and services. These approvals may include safety provisions with respect to pipeline routing, safety standards, and other factors.³¹ In particular, pipeline and aboveground facilities associated with a proposed pipeline project must be designed in accordance with PHMSA's safety standards regarding material selection and qualification, design requirements, and protection from corrosion.³²

PHMSA and FERC cooperate on pipeline safety-related matters, according to an MOU signed in 1993. According to the MOU, PHMSA agrees to

• promptly alert FERC when safety activities may impact commission responsibilities;
• notify FERC of major accidents or significant enforcement actions involving pipelines under FERC's jurisdiction;
• refer to FERC any complaints and inquiries by state and local governments and the public about environmental or certificate matters related to FERC-jurisdictional pipelines; and,
• when requested by FERC, review draft mitigation conditions considered by the commission for potential conflicts with PHMSA's regulations.

Under the MOU, FERC agrees to

• promptly alert PHMSA when the commission learns of an existing or potential safety problem involving natural gas transmission facilities;
• notify PHMSA of future pipeline construction;
• periodically provide PHMSA with updates to the environmental compliance inspection schedule and coordinate site inspections, upon request, with PHMSA officials;
• notify PHMSA when significant safety issues have been raised during the preparation of environmental assessments or environmental impact statements for pipeline projects; and
• refer to PHMSA complaints and inquiries made by state and local governments and the public involving safety matters related to FERC-jurisdictional pipelines.³³

FERC may also serve as a member of PHMSA's Technical Pipeline Safety Standards Committee, which determines whether proposed safety regulations are technically feasible, reasonable, cost-effective, and practicable.

In April 2015, FERC issued a policy statement to provide "greater certainty regarding the ability of interstate natural gas pipelines to recover the costs of modernizing their facilities and infrastructure to enhance the efficient and safe operation of their systems."³⁴ FERC's policy statement was motivated by the commission's expectation that governmental safety and environmental initiatives could cause greater safety and reliability costs for interstate gas pipeline systems.³⁵

PHMSA and the NTSB

The NTSB is an independent federal agency charged with determining the probable cause of transportation incidents—including pipeline releases—and promoting transportation safety. The board's experts investigate significant incidents, develop factual records, and issue safety recommendations to prevent similar events from reoccurring. The NTSB has no statutory authority to regulate transportation, however, and it does not perform cost-benefit analyses of regulatory changes; its safety recommendations to industry or government agencies are not mandatory. Nonetheless, because of the board's strong reputation for thoroughness and objectivity, 82% of the NTSB's safety recommendations have been implemented across all transportation modes.³⁶

In the pipeline sector, the NTSB's past safety recommendations have led to changes in pipeline safety regulation regarding one-call systems before excavation ("call before you dig"), use of pipeline internal inspection devices, facility response plan effectiveness, hydrostatic pressure testing of older pipelines, and other safety improvements.³⁷ As of April 15, 2025, the NTSB listed 11 open pipeline safety recommendations to PHMSA. In eight cases, the NTSB has classified PHMSA's responses to these recommendations as "Acceptable" because they are being incorporated satisfactorily in ongoing PHMSA rulemakings or because PHMSA is implementing other measures to meet the same objectives. In three cases (all stemming from the 2023 West Reading accident), the NTSB is awaiting PHMSA's response to its recommendations. Detailed discussion of NTSB pipeline accident investigations and safety recommendations are publicly available through the NTSB's Case Analysis and Reporting Online query tool.³⁸ In addition to making specific safety recommendations, the NTSB may also comment on proposed changes to PHMSA's pipeline safety regulations, such as those involving pipeline hazard class locations and standards for valve installation and rupture detection, among other standards.³⁹

PHMSA's Role in Pipeline Security

Pipeline safety and security are distinct issues involving different threats, statutory authorities, and regulatory frameworks. Nonetheless, aspects of pipeline safety and security can be intertwined. PHMSA has historically played a significant role in pipeline security and continues to be involved in pipeline security oversight and incident response. The 2021 ransomware attack on the Colonial Pipeline Company, which disrupted gasoline supplies throughout the East Coast, elevated concern in Congress about federal oversight of pipeline security, including PHMSA's role within the nation's pipeline security framework.⁴⁰

DOT's Early Role in Pipeline Security

DOT played the leading role in pipeline security through the late 1990s. Presidential Decision Directive 63 (PDD-63), issued during the Clinton Administration, assigned lead responsibility for pipeline security to DOT.⁴¹ These responsibilities fell to OPS, at that time a part of DOT's Research and Special Programs Administration, because the agency was already addressing some elements of pipeline security in its role as safety regulator.⁴² DOT's pipeline (and LNG) safety regulations already included provisions related to physical security, such as requirements to protect surface facilities (e.g., pumping stations) from vandalism and unauthorized entry.⁴³ Other regulations required continuing surveillance, patrolling pipeline rights-of-way, damage prevention, and emergency procedures.⁴⁴

On September 5, 2002, OPS circulated formal guidance developed in cooperation with the pipeline industry associations defining the agency's security program recommendations and implementation expectations. This guidance recommended that operators identify critical facilities, develop security plans consistent with prior trade association security guidance, implement these plans, and review them annually.⁴⁵ While the guidance was voluntary, OPS expected compliance and informed operators of its intent to begin reviewing security programs and to test their effectiveness.⁴⁶

PHMSA Cooperation with TSA

In November 2001, President Bush signed the Aviation and Transportation Security Act (P.L. 107-71) establishing the Transportation Security Administration (TSA) within DOT. According to TSA, the act placed DOT's pipeline security authority (under PDD-63) within TSA. The act specified for TSA a range of duties and powers related to general transportation security, such as intelligence management, threat assessment, mitigation, security measure oversight, and enforcement. On November 25, 2002, President Bush signed the Homeland Security Act of 2002 (P.L. 107-296) creating the Department of Homeland Security (DHS). Among other provisions, the act transferred TSA from DOT to DHS (§403). On December 17, 2003, President Bush issued Homeland Security Presidential Directive 7 (HSPD-7), clarifying executive agency responsibilities for identifying, prioritizing, and protecting critical infrastructure.⁴⁷ HSPD-7 maintained DHS as the lead agency for pipeline security (paragraph 15) and instructed DOT to "collaborate in regulating the transportation of hazardous materials by all modes (including pipelines)" (paragraph 22h).

In 2004, DOT and DHS entered into an MOU concerning their respective security roles in all modes of transportation. The MOU notes that DHS has the primary responsibility for transportation security with support from DOT and establishes a general framework for cooperation and coordination. The MOU states that "specific tasks and areas of responsibility that are appropriate for cooperation will be documented in annexes … individually approved and signed by appropriate representatives of DHS and DOT."⁴⁸ On August 9, 2006, the departments signed an annex "to delineate clear lines of authority and responsibility and promote communications, efficiency, and nonduplication of effort through cooperation and collaboration between the parties in the area of transportation security."⁴⁹

In January 2007, the PHMSA administrator testified before Congress that the agency had established a joint working group with TSA "to improve interagency coordination on transportation security and safety matters, and to develop and advance plans for improving transportation security," presumably including pipeline security.⁵⁰ According to TSA, the working group developed a multiyear action plan specifically delineating roles, responsibilities, resources, and actions to execute 11 program elements: identification of critical infrastructure/key resources and risk assessments, strategic planning, developing regulations and guidelines, conducting inspections and enforcement, providing technical support, sharing information during emergencies, communications, stakeholder relations, research and development, legislative matters, and budgeting.⁵¹

Clarifying PHMSA and TSA Security Roles

P.L. 109-468 required the DOT inspector general (IG) to assess the pipeline security actions taken by DOT in implementing its 2004 MOU with DHS (§23). The IG published this assessment in May 2008. The IG report stated,

PHMSA and TSA have taken initial steps toward formulating an action plan to implement the provisions of the pipeline security annex…. However, further actions need to be taken with a sense of urgency because the current situation is far from an "end state" for enhancing the security of the Nation's pipelines.⁵²

The report recommended that PHMSA and TSA finalize and execute their security annex action plan, clarify their respective roles, and jointly develop a pipeline security strategy that maximizes the effectiveness of their respective capabilities and efforts.⁵³ According to TSA, working with PHMSA "improved drastically" after the release of the IG report; the two agencies began to maintain daily contact, share information in a timely manner, and collaborate on security guidelines and incident response planning.⁵⁴ Consistent with this assertion, in March 2010, TSA published a Pipeline Security and Incident Recovery Protocol Plan, which lays out in detail the separate and cooperative responsibilities of the two agencies with respect to a pipeline security incident. Among other notes, the plan states,

DOT has statutory tools that may be useful during a security incident, such as special permits, safety orders, and corrective action orders. DOT/PHMSA also has access to the Regional Emergency Transportation Coordinator (RETCO) Program…. Each RETCO manages regional DOT emergency preparedness and response activities in the assigned region on behalf of the Secretary of Transportation.⁵⁵

The plan also refers to the establishment of an Interagency Threat Coordination Committee established by TSA and PHMSA to organize and communicate developing threat information among federal agencies that may have responsibility for pipeline incident response.⁵⁶

DOT has continued to cooperate with TSA on pipeline security over the last decade. For example, TSA coordinated with DOT and other agencies to address ongoing vandalism and sabotage against critical pipelines by environmental activists in 2016.⁵⁷ In April 2016, the director of TSA's Surface Division testified about her agency's relationship with DOT:

TSA and DOT co-chair the Pipeline Government Coordinating Council to facilitate information sharing and coordinate on activities including security assessments, training, and exercises. TSA and DOT's Pipeline and Hazardous Materials Safety Administration (PHMSA) work together to integrate pipeline safety and security priorities, as measures installed by pipeline owners and operators often benefit both safety and security.⁵⁸

In December 2016, PHMSA issued an Advisory Bulletin "in coordination with" TSA regarding cybersecurity threats to pipeline Supervisory Control and Data Acquisition systems.⁵⁹ In July 2017, the two agencies collaborated on a web-based portal to facilitate sharing sensitive but unclassified incident information among federal agencies with pipeline responsibilities.⁶⁰ In February 2018, the director of TSA's Surface Division again testified about cooperation with PHMSA, stating, "TSA works closely with [PHMSA] for incident response and monitoring of pipeline systems," although she did not provide specific examples.⁶¹

In June 2019, the Government Accountability Office (GAO) published a report examining the relative roles and responsibilities of DOT and DHS in pipeline security.⁶² GAO concluded that, while the 2006 TSA-PHMSA MOU Annex delineated the agencies' mutually agreed-upon roles and responsibilities, it had not been reviewed to consider pipeline security developments since its inception. TSA's Pipeline Security and Incident Recovery Protocol Plan likewise had not been updated since it was issued in 2010 "to reflect changes in pipeline security threats, technology, federal law and policy, and any other factors."⁶³ Among other things, GAO recommended that TSA and PHMSA update these documents and put in place formal processes to periodically update them in the future. In response to this recommendation, TSA and PHMSA signed an update to the MOU Annex in February 2020.⁶⁴ In its November 2024 proposed rule to regulate pipeline (and rail) cybersecurity, TSA states that it "will coordinate activities under this part with ... PHMSA of the DOT with respect to regulation of pipeline systems ... to avoid conflicting requirements and minimize redundancy of compliance activities."⁶⁵

Colonial Pipeline Incident

Following the Colonial Pipeline ransomware attack, PHMSA joined TSA and the Cybersecurity and Infrastructure Security Agency (CISA) on a teleconference call with pipeline operators to provide updates on the incident, answer questions, and provide resources to support cybersecurity mitigation efforts.⁶⁶ The Deputy Secretary of Transportation subsequently testified that PHMSA intended to "leverage its authorities to inspect and enforce three critical components of pipeline operations" related to cybersecurity: system control room regulations, integrity management plan requirements,⁶⁷ and emergency response plan regulations.⁶⁸ The Deputy Secretary also stated that DOT's Office of Intelligence, Security, and Emergency Response was collaborating with the National Security Council and interagency partners on a natural gas pipelines Industrial Control Systems Cybersecurity Initiative and that "DOT continues work with [its] sister agencies, especially TSA and CISA, to invest in world class research and pursue initiatives to address cybersecurity threats."⁶⁹

Policy Issues for Congress

PHMSA's pipeline safety authorization expired at the end of FY2023, although the agency has continued to receive funding under subsequent appropriations. In considering future reauthorization, Congress may focus on oversight of the agency's ongoing regulatory activities and implementation of its most recent legislative priorities. Among these issues, the following may be of particular interest, in no particular order: staffing resources; pipeline modernization; new regulation of gas gathering lines; regulation of methane leaks; PHMSA's role in pipeline security; updates to regulation of LNG, carbon dioxide, and hydrogen infrastructure; special permits; class location; pipeline safety R&D; and repair criteria. These issues are discussed in the following sections.

Staffing Resources for Pipeline Safety

The U.S. pipeline safety program employs a combination of federal and state staff to implement and enforce federal pipeline safety regulations. To date, PHMSA has relied heavily on state agencies for pipeline inspections, with over three-quarters of inspectors being state employees. As the PHMSA administrator remarked in 2018,

PHMSA faces a manpower issue. It is obvious that [PHMSA] … cannot oversee 2.7 million miles of pipeline all by itself. In fact, PHMSA makes no attempt to do so. Most actual safety inspections are performed by our state partners.⁷⁰

Nonetheless, some in Congress have criticized staffing at PHMSA for being insufficient to inspect pipelines under the agency's jurisdiction and to revise its regulations in line with legislative mandates and deadlines. In considering PHMSA staffing levels, issues of particular interest have been the number of federal inspectors and the agency's historical use of staff funding.

In FY2023, PHMSA was funded for 356 full-time equivalent (FTE) employees in pipeline safety. This total included eight new FTE positions required by the PIPES Act of 2020 (§102) "to finalize outstanding rulemakings and fulfill congressional mandates." PHMSA's enacted budget authority for FY2024 and FY2025 included funding for 365 FTE employees in both years.⁷¹

Figure 5. PHMSA Pipeline Safety Staffing, Historical and Enacted, 2015-2025 (Full-Time Equivalent Staff)

Sources: U.S. Office of Management and Budget, Budget of the United States Government: Appendix, Fiscal Years 2016-2025, "Pipeline Safety," line 1001, "Direct civilian full-time equivalent employment"; Linda Daugherty, PHMSA, email communication, April 16, 2025. Notes: These figures assume all staff are full-time equivalent employees (FTEs). Funded staff are "estimated staff" anticipated by the agency as reported in annual budget requests. They differ from actual staff employed (for the same fiscal year) as reported in subsequent budget requests. Pipeline safety FTEs in the figure include pipeline safety positions reporting directly through the Office of Pipeline Safety and through other program offices.

As Figure 5 shows, PHMSA has faced a persistent staffing shortfall, which has generally been due to a shortage of inspectors. Agency officials have offered a number of reasons for the shortfall, including a scarcity of qualified inspector job applicants, delays in the federal hiring process (during which applicants accept other job offers), and PHMSA inspector turnover—especially due to retirements and departures to pipeline companies. Because PHMSA pipeline inspectors are extensively trained by the agency—typically for two years before being allowed to operate independently—they are highly valued by pipeline operators seeking to comply with federal safety regulations.

A 2017 DOT IG report supported PHMSA's assertions about industry-specific hiring challenges and confirmed "a significant gap between private industry and Federal salaries for the types of engineers PHMSA hires."⁷² PHMSA has continued to experience staff losses due to an aging workforce and continued difficulty hiring and retaining engineers and technical staff because of competition from the oil and natural gas industry as well as lingering workforce challenges related to the COVID-19 pandemic.⁷³

Although PHMSA has acted in recent years to shore up its workforce, there have been recommendations for improvement. A 2018 GAO study stated that PHMSA had not "planned for future workforce needs for interstate pipeline inspections" and, in particular, had not assessed the resources and benefits available from its state partners.⁷⁴ GAO concluded that without this type of forward-looking analysis, PHMSA could not "proactively plan for future inspection needs to ensure that federal and state resources are in place to provide effective oversight of interstate pipelines."⁷⁵ According to GAO, PHMSA concurred with its recommendation to develop a workforce plan for interstate pipeline inspections.

The PIPES Act of 2020 (§102(b)) established a yearly minimum number of FTEs for pipeline safety inspection and enforcement for FY2021-FY2023. The act also required PHMSA to "use incentives, as necessary, to recruit and retain a qualified workforce" as permitted under Title 5 of the U.S. Code, including special pay rates, student loan repayment, tuition assistance, and retention incentives. The agency has long been taking measures to address its staffing challenges, such as using Direct Hiring Authority for applicable positions; investing in education programs promoting pipeline safety engineering; developing targeted recruitment and hiring strategies for key positions; extending outreach among universities and professional associations; and participating in special hiring events, among other activities.⁷⁶ PHMSA has also received approval for a special pay rate table from the Office of Personnel Management for a 35% premium for engineer inspectors in its five regional offices, and PHMSA continues to implement other financial incentives, including recruitment and retention bonuses, tuition assistance, and student loan repayment.⁷⁷

The second Trump Administration has stated plans to downsize the federal workforce, which it has indicated may involve actions in which individuals' employment with federal agencies is ended either voluntarily or involuntarily.⁷⁸ There are several preexisting voluntary and involuntary mechanisms the executive branch may use to downsize its workforce. In January, the Trump Administration announced a voluntary deferred resignation program.⁷⁹ According to press reports, some senior PHMSA staff have accepted the Administration's retirement offers, and other staff may be subject to involuntary separation, although the agency has made no public statements about staff departures.⁸⁰ What impact the Trump Administration's government downsizing efforts may have on PHMSA's future staffing levels—and how they may affect the agency's ability to effectively carry out its mission—may be of interest to Congress.

Aging Pipeline Modernization

The NTSB listed the safe shipment of hazardous materials by pipeline among its 2019-2020 Most Wanted List of Transportation Safety Improvements, stating "as infrastructure ages, the risk to the public from pipeline ruptures also grows."⁸¹ Likewise, Congress has been concerned about the safety of older transmission pipelines—a key factor in the San Bruno, CA, accident—and in leaky and deteriorating cast iron pipe in natural gas distribution systems—at issue in Merrimack Valley.⁸² Construction work in Merrimack Valley, which led to the release of natural gas, was part of a cast iron pipe replacement project. According to the American Gas Association and other stakeholders, antiquated cast iron pipes in natural gas distribution systems, many over 50 years old, "have long been recognized as warranting attention in terms of management, replacement and/or reconditioning."⁸³ Old distribution pipes have also been identified as a significant source of methane leakage, which poses safety risks and contributes to U.S. GHG emissions.⁸⁴

Natural gas distribution system operators with antiquated pipes in their systems all have programs for their replacement, although some are constrained by costs and rate regulation. Upgrading or replacing natural gas distribution infrastructure involves substantial capital investment. According to a 2015 Department of Energy analysis, the total cost of replacing all cast iron and bare steel distribution pipes in the United States at that time would have been approximately $270 billion (2015 dollars).⁸⁵ These costs, in turn, could be passed on to consumers through increased natural gas rates. The costs could pose particular challenges for publicly owned (e.g., municipal) gas utilities with constrained budgets and limited access to capital. Practical barriers, such as urban excavation and disruption of gas supplies, also constrain annual pipe replacement. Nonetheless, as the Department of Energy stated in a 2017 report, "many policymakers and the utilities responsible for delivering natural gas to customers broadly recognize the need to accelerate ongoing efforts to replace aging infrastructure while embracing new approaches to operations and maintenance."⁸⁶

Although the federal role in natural gas distribution systems is limited because they are under state jurisdiction, there have been past legislative proposals in Congress to provide federal support for the replacement of old cast iron pipe.⁸⁷ Likewise the House Select Committee on the Climate Crisis majority staff report, released in June 2020, concluded that Congress should "provide financial support for cities and states to eliminate methane leaks from natural gas distribution lines within 10 years."⁸⁸ Consistent with these efforts, IIJA authorized a Natural Gas Distribution Infrastructure Safety and Modernization Grant Program (NGDISM), administered by PHMSA. The program was designed to provide grants to municipal or community-owned natural gas distribution utilities (excluding for-profit utilities) for the repair, rehabilitation, or replacement of some or all of their pipeline systems in order to reduce safety incidents and "avoid economic losses." IIJA appropriated a total of $1.0 billion for the program in $200 million increments annually from FY2022 to FY2026 to remain available until expended.

PHMSA announced it had begun accepting applications for the grants in May 2022.⁸⁹ According to the DOT FY2024 budget request, the agency awarded no grants in FY2022 but expected to award $392 million in grants through the end of FY2023.⁹⁰ In May 2024 testimony, PHMSA's deputy administrator stated,

We have been delighted to see the interest and excitement from grant applicants and recipients and are happy to say that the NGDISM program is working. During our first year of project solicitations, the program attracted nearly $1.8 billion worth of applications for $200 million in funding. We had similar interest when we announced the FY23 and FY24 round of funding.... And this week, we are issuing another Notice of Funding Opportunity for the FY25 round of funding, which I know applicants are eager to apply for... Although the program is funded through 2026, PHMSA anticipates the work in carrying out and overseeing the infrastructure projects from the NGDISM program won't be completed until 2033.⁹¹

On January 20, 2025, President Trump issued Executive Order 14154, "Unleashing American Energy," which, among other provisions, directs agencies to pause disbursement of funds appropriated in the IIJA and to "review their processes, policies, and programs for issuing grants."⁹² As of the date of this report, an FY2025 funding opportunity does not appear on PHMSA's website for the NGDISM grant program, nor is there an NGDISM grant opportunity listed in Grants.gov.

As PHMSA's implementation of the NGDISM program continues, Congress may examine its structure and effectiveness along with the industry's overall progress in addressing the safety of antiquated distribution lines.

Gathering Line Regulation

Natural gas gathering lines are pipelines that collect produced gas from wellheads and transport it to centralized collection points. The latter are usually gas processing facilities where impurities are removed and gas constituents (e.g., methane, propane) are separated into distinct products for further shipment to market. Natural gas gathering lines have historically operated in mostly rural areas at lower pressure than transmission lines and with smaller diameters—typically 20 inches or less. However, due to differences in extraction techniques, especially in shale gas production with hydraulic fracturing, newer gathering lines have been constructed up to 36 inches in diameter and operated at pressures similar to those in transmission lines.⁹³ Shale gas production has also been occurring in relatively more populated areas, notably the Marcellus basin in Ohio, Pennsylvania, and West Virginia. The construction of larger gathering lines in more populous regions, together with recent gathering pipeline accidents, has raised concerns about safety risks in nearby communities.

The Pipeline Safety Act of 1992 (P.L. 102-508, §109) authorized PHMSA to regulate the safety of gas gathering lines that "warrant regulation," taking account of "such factors as location, length of line from the well site, operating pressure, throughput, and the composition of the transported gas." Under these provisions, PHMSA issued a 2006 final rule defining regulated gathering line that covered less than 10% of U.S. natural gas gathering line mileage at the time.⁹⁴ The remaining gathering lines were judged to pose little risk to the public due to their physical characteristics and more remote locations.

In 2011, PHMSA published an Advance Notice of Proposed Rulemaking to begin examining, among other things, whether new regulations were needed to govern the safety of natural gas gathering lines—with specific reference to shale gas lines.⁹⁵ Continuing this rulemaking process, in 2016, PHMSA published a Notice of Proposed Rulemaking (NPRM) to modify the regulation of onshore gas gathering lines—repealing an exemption for operator reporting and extending specific regulatory requirements to certain gas gathering lines with large diameters and high operating pressures in certain locations.⁹⁶

The PIPES Act of 2020 (§112(a)) required PHMSA to finalize its rule for onshore gas gathering lines by March 27, 2021. PHMSA published its final rule in the Federal Register on November 15, 2021.⁹⁷ Among its key provisions, the rule requires operators to report incidents and file annual reports for all natural gas gathering lines to "help determine the need for future regulatory changes to address the risks to the public, property and the environment."⁹⁸ According to PHMSA's announcement, under this requirement, "there are at least 425,000 miles of onshore gas gathering lines that have not been subject to PHMSA oversight but will be after this rule takes effect."⁹⁹

The final rule also imposes new safety requirements (e.g., for damage prevention, construction, and operation) on gathering lines that have outer diameters of 8.625 inches or greater and operate at higher stress levels or pressures, with greater requirements for lines larger than 16 inches and certain gathering lines that could directly affect homes and other structures.¹⁰⁰ PHMSA estimated at the time of the rule that approximately 91,000 miles of gathering lines fell into this category.¹⁰¹ Operators were required to comply with safety requirements for the larger gathering lines as of May 16, 2022, with initial annual reports due by May 15, 2023.

Pipeline stakeholder representatives participated in PHMSA's gathering line rulemaking process both as members of technical panels and as commenters on the proposed rule. While stakeholders reached a consensus on many provisions in PHMSA's final rule, some remained the subject of disagreement. In December 2021, two pipeline trade associations filed a petition with PHMSA to stay enforcement and reconsider a number of specific requirements due to disagreement with the agency's risk assessment and cost-benefit determination, arguing that PHMSA was imposing excessive and unnecessary burdens on operators.¹⁰² Conversely, pipeline safety advocates supported implementing the agency's final rule "unhindered," citing the perceived "progress" in gathering line safety and concerns about industry's potentially negative influence on PHMSA's safety regulation.¹⁰³ In April 2022, PHMSA denied the petition for reconsideration of the final rule.¹⁰⁴ As PHMSA's final gathering line rule continues to be implemented, compliance among operators and the effects of the final rule on overall safety in the pipeline sector may be oversight issues for Congress.

PHMSA Regulation of Methane Leaks and Emissions

The Environmental Protection Agency's Greenhouse Gas Inventory lists "natural gas systems" as among the highest U.S. emissions sources of atmospheric methane, a potent GHG.¹⁰⁵ Within this category, studies have identified pipeline emissions—arising from leaks, planned maintenance releases, accidents, and other releases—as a major source of fugitive methane.¹⁰⁶ Given national goals to reduce GHG emissions in an effort to limit climate change, some in Congress have called for tighter regulation of pipeline methane releases to reduce the sector's GHG contribution.¹⁰⁷ Reflecting these views, the PIPES Act (§113) mandates that PHMSA promulgate regulations requiring natural gas pipeline operators "to conduct leak detection and repair programs … to meet the need for gas pipeline safety, as determined by the Secretary; and … to protect the environment" (emphasis added). The act similarly requires PHMSA to evaluate "protection of the environment" as a factor in its review of pipeline operators' inspection and maintenance plans (§114).

The inclusion by Congress of explicit language in the PIPES Act about protecting "the environment" has been widely viewed as expanding PHMSA's traditional safety mission to include climate considerations. As PHMSA's former acting administrator stated in 2021, "we need to do all we can to prevent climate change[,] and reducing leaks which contribute to methane emission is a critical part of that."¹⁰⁸ The Biden Administration likewise cited the PIPES Act provisions as elements of a national strategy to "to tackle super-polluting methane emissions—a major contributor to climate change."¹⁰⁹

The inspection and maintenance plan provisions in the PIPES Act (§114) are self-executing, applying directly to pipeline operators. PHMSA published an advisory bulletin in the Federal Register in June 2021 reminding pipeline operators to update their plans by the statutory deadline of December 27, 2021.¹¹⁰

In compliance with Section 113 of the PIPES Act, on January 17, 2025, PHMSA posted a final rule for "Gas Pipeline Leak Detection and Repair" (LDAR) on its website.¹¹¹ The rule would "require pipeline operators to establish advanced leak detection programs aimed at detecting and repairing all gas leaks" (emphasis added) through a set of new or expanded requirements:

• Increasing leak survey frequency and requiring the use of advanced leak detection technology.
• Reducing unintentional gas emissions (e.g., from leaks and equipment failures) and lowering the minimum volume threshold for reporting leaks.
• Minimizing intentional gas releases from planned pipeline maintenance, repair, and construction activities, and encouraging the use of methane capture equipment.
• Setting clear criteria and time frames for repairing all leaks that pose a safety or environmental risk.¹¹²

On January 17, 2025, PHMSA also submitted the LDAR final rule to the Office of the Federal Register (OFR) for publication in the Federal Register, the final statutory requirement for the rule to take effect. However, on January 20, 2025, President Trump issued a memorandum, "Regulatory Freeze Pending Review," ordering "all executive departments and agencies" to "immediately withdraw any rules that have been sent to the OFR but not published in the Federal Register, so that they can be reviewed and approved."¹¹³ In compliance with the memorandum, PHMSA withdrew the LDAR final rule from Federal Register publication, so the rule is not in effect and operators are not required to comply with it. The future status of the rule under the Trump Administration remains to be seen.

Given the PIPES Act's mandate that PHMSA incorporate new environmental considerations in its pipeline safety standards, its Section 114 enforcement and Section 113 rulemaking continue to be of great interest among industry and environmental stakeholders as well as in Congress. As PHMSA implements the environmental protection and leak-related provisions in the PIPES Act, Congress may examine how the agency quantifies the costs and benefits of climate-related regulatory requirements, potential impacts to pipeline operations, how new information on methane leaks can inform future regulation, and how new technologies could improve leak identification and mitigation.

PHMSA and Pipeline Security

Ongoing physical and cyber threats against the nation's pipelines have heightened concerns about pipeline security risks. In a December 2018 study, GAO stated that, since the terrorist attacks of September 11, 2001, "new threats to the nation's pipeline systems have evolved to include sabotage by environmental activists and cyber attack or intrusion by nations."¹¹⁴ The 2021 ransomware attack on the Colonial Pipeline Company brought pipeline security to the fore. Recent oversight of federal pipeline safety and security activities has included discussion of PHMSA's role in pipeline security.

In October 2021, PHMSA's acting administrator stated that the agency's security role "includes coordination efforts with [TSA] and other federal agencies to ensure there is a collaborative and efficient approach to monitoring, inspecting, and promulgating regulations related to cybersecurity in the pipeline industry."¹¹⁵ While PHMSA has reported past cooperation with TSA in pipeline security under the terms of the pipeline security annex and subsequent collaboration, questions may remain regarding the ongoing roles of the two agencies. Some in Congress have been interested in PHMSA's role in the overall federal regulatory structure overseeing pipeline security, particularly cybersecurity, and incident response.¹¹⁶ In March 2023 testimony before Congress, the PHMSA Deputy Administrator stated,

We work very closely with [TSA].... There are operational impacts, potentially, when you have a cyberattack, and we're responsible for [overseeing] safe operations.... We've provided our input to the Transportation Security Administration on their proposed security directives on cybersecurity and we've engaged with leadership of pipeline companies ... to make sure we're all on the same page.¹¹⁷

In past Congresses, some legislative proposals would have promoted greater coordination among federal agencies and state government agencies and the energy sector in pipeline security.¹¹⁸ What role PHMSA might play in any future pipeline security initiatives, and what resources it might require to perform that role, may be a consideration for Congress.

Carbon Dioxide Pipeline Rulemaking

Carbon dioxide (CO₂) pipelines are essential components of carbon capture and storage (CCS) systems, which are proposed to reduce atmospheric emissions of anthropogenic CO₂, a greenhouse gas.¹¹⁹ Pipelines are needed to transport the CO₂ from where it is captured (e.g., power plants) to the underground geologic formations where it can be stored. Approximately 5,300 miles of pipeline already carry CO₂ in the United States (Table 1), primarily linking natural CO₂ sources to aging oil fields where the CO₂ is used for enhanced oil recovery. However, a larger CO₂ pipeline network could be needed for CCS to significantly reduce U.S. greenhouse gas emissions. A 2021 study suggested that such a network could total some 66,000 miles of pipeline by 2050, requiring some $170 billion in new capital investment.¹²⁰ Because CO₂ in high concentrations can be hazardous to human health, building out a national CO₂ pipeline network raises safety issues that may affect communities near such a network and may hinder CCS deployment because of public concerns about safety.

CO₂ occurs naturally in the atmosphere and is produced by the human body, so it is often perceived to be relatively harmless. However, as concentrations increase, CO₂ displaces oxygen—which may cause a range of negative health impacts, including suffocation.¹²¹ Pipeline CO₂ also may contain potentially hazardous contaminants, such as hydrogen sulfide. Because CO₂ is colorless, odorless, and heavier than air, an uncontrolled release may spread undetected near the ground or in confined spaces. Therefore, CO₂ pipelines pose a public safety risk, as demonstrated by the 2020 CO₂ pipeline rupture in Satartia, MS, which led to a local evacuation and caused 45 people to be hospitalized.¹²²

PHMSA has promulgated and enforces regulations for construction, operation and maintenance, and emergency response planning for CO₂ pipelines.¹²³ Although CO₂ is listed as a Class 2.2 (nonflammable gas) hazardous material under DOT regulations, PHMSA currently applies safety requirements to CO₂ pipelines similar to those for pipelines carrying hazardous liquids such as crude oil and anhydrous ammonia.¹²⁴ Prior to the Satartia accident, according to PHMSA statistics, CO₂ pipeline operators reported only one injury and no fatalities caused by regulated pipelines over the last 20 years. However, pipeline safety advocates have argued that PHMSA's regulations for CO₂ pipelines are insufficient with respect to hazard zones around CO₂ releases, potential pipeline fractures, and corrosion of CO₂ pipeline steel, among other things.¹²⁵

Concerns about CO₂ pipeline safety have emerged as an issue for developing CCS projects, especially in the Upper Midwest, where several CO₂ pipeline projects have been proposed in recent years.¹²⁶ These pipelines have faced opposition among affected landowners and advocacy groups for reasons including risks to public safety. As a consequence, the developers have faced resistance securing voluntary agreements with landowners for pipeline rights-of-way through their properties and there have been regulatory interventions and legislative efforts to limit state eminent domain authority for such projects.¹²⁷

The Pipeline Safety, Regulatory Certainty, and Job Creation Act of 2011 (P.L. 112-90, §15) directed PHMSA to "prescribe minimum safety standards for the transportation of carbon dioxide by pipeline in a gaseous state" and to "consider" whether applying the safety standards in effect at that time for transporting liquid carbon dioxide or gaseous carbon dioxide "would ensure safety." In response to this previously unfulfilled mandate, and findings from its own Satartia accident investigation, PHMSA announced a rulemaking on May 26, 2022, to update its CO₂ pipeline safety standards and a research solicitation to study the impact of CO₂ pipeline releases.¹²⁸

On January 15, 2025, PHMSA announced an NPRM to "strengthen existing standards for hazardous liquid and CO₂ pipelines (including CO₂ that is transported in a supercritical fluid state), and for the first-time, establish new standards for transporting carbon dioxide in a gaseous state via pipeline."¹²⁹ If adopted, the rule would establish new safety requirements for CO₂ pipelines, including

• establishing design, installation, operation, maintenance, and reporting requirements for CO₂ gas pipelines;
• establishing new requirements for converting existing pipelines to transport CO₂ in different phases;
• requiring CO₂ pipeline operators to provide training to emergency responders and ensure the availability of CO₂ detection and other equipment for emergency response;
• implementing more robust requirements for public communication during an emergency; and
• requiring more detailed CO₂ vapor dispersion analyses to better protect the public and the environment in a pipeline failure.¹³⁰

According to PHMSA, the agency submitted the NPRM for publication in the Federal Register concurrently with its posting on its website.¹³¹ However, as in the case of the LDAR final rule, in accordance with President Trump's memorandum, "Regulatory Freeze Pending Review," PHMSA subsequently withdrew the CO₂ pipeline NPRM from Federal Register publication. Consequently, the proposed rule is not "official" and is not open for public comment.

Given the fundamental need for pipelines in CCS systems, actual or perceived safety risks associated with CO₂ pipelines may limit the potential of CCS as a greenhouse gas mitigation option. Opposition to siting of pipelines due to safety concerns may prevent CO₂ pipeline development in certain localities and increase development time and costs in others. How PHMSA will proceed with its CO₂ pipeline NPRM under the Trump Administration is uncertain, but CO₂ pipeline safety, and its implications for CCS deployment, may be an oversight issue for Congress.

Hydrogen Pipeline Safety

Some in Congress have proposed hydrogen as an environmentally friendlier alternative to conventional fossil fuels for vehicles, vessels, and electric power generation. IIJA authorized an $8 billion program of Regional Clean Hydrogen Hubs, which would be centers of activity involving hydrogen production, delivery, and end use.¹³² Supplying hydrogen from sources like regional hubs to power plants, industrial facilities, and vehicular fuel distribution centers could require the development of an expansive hydrogen pipeline network.

Shipping hydrogen by pipeline in the United States is not new, but the existing pipeline network is relatively small and located almost entirely along the Gulf Coast. There are approximately 1,600 miles of active hydrogen pipeline in the United States (Table 1), with over 90% located in Texas, Louisiana, and Alabama, primarily serving refineries and ammonia plants.¹³³ The pipeline network required to support a hydrogen-based U.S. energy strategy would need to be much larger. To facilitate the pipeline transportation of hydrogen, some in Congress, in the pipeline industry, and in the executive branch have proposed blending significant hydrogen volumes with methane in existing natural gas pipelines.¹³⁴

Transporting hydrogen by pipeline, especially in existing natural gas pipelines, poses safety challenges due to hydrogen's chemical characteristics. Hydrogen molecules are the smallest of all molecules, and therefore are more prone than methane (the principal component of natural gas) to leak through joints, microscopic cracks, and seals in pipelines and associated infrastructure.¹³⁵ Hydrogen can also permeate directly through polymer (plastic) materials, such as those typically used to make natural gas distribution pipes. The presence of hydrogen can deteriorate steel pipe, pipe welds, valves, and fittings through a variety of mechanisms, particularly embrittlement.¹³⁶ In 2022, a safety advocacy group published a report on hydrogen blending that "identifies serious concerns about the pursuit of hydrogen blending options for existing gas transmission or gas distribution pipelines" due to the potential for pipeline leaks and failures and the greater flammability of hydrogen compared to methane.¹³⁷ However, a pipeline industry trade group disagreed with these findings, pointing to operator experience safely transporting hydrogen blends.¹³⁸

PHMSA's pipeline safety authority extends to hydrogen pipelines, which the agency has regulated since 1970 as a "flammable gas."¹³⁹ PHMSA does not currently prohibit natural gas pipeline operators from introducing hydrogen into their systems. However, some stakeholders have questioned whether PHMSA's existing regulations are appropriate and sufficient to ensure the safety of an expanding hydrogen pipeline network, especially if it includes existing natural gas pipelines carrying hydrogen blends.¹⁴⁰ For example, the agency does not currently require operators to report information about hydrogen blends in their pipeline systems if natural gas is the dominant commodity. A 2021 Sandia National Laboratories report reviewing pipeline industry standards concluded,

There are many safety codes and standards that are relevant to hydrogen blending in the natural gas infrastructure. Relevant codes include those that address natural gas and hydrogen specifically, as well as those that address blended gasses. However, there are gaps that will need to be addressed when considering introducing hydrogen/natural gas blends into the current infrastructure.¹⁴¹

PHMSA's research and development program database currently lists 13 active projects related to hydrogen infrastructure safety funded under its existing research grant program.¹⁴² Congress has promoted additional federal initiatives around hydrogen pipeline safety-related research and development. The IIJA directs the Secretary of Energy to advance the safe and efficient delivery of hydrogen or hydrogen-carrier fuels in pipelines, including by retrofitting existing natural gas pipelines (§40313). In the 118^th Congress, the Hydrogen Infrastructure Finance and Innovation Act (S. 649; H.R. 7200) would have established a DOE hydrogen infrastructure finance and innovation pilot program. The act also would have required federal agencies, including PHMSA, to cooperatively study outstanding questions regarding research, development, and demonstration of hydrogen pipeline infrastructure and to separately study "jurisdiction over the siting, construction, safety, and regulation of hydrogen transportation infrastructure, including, at a minimum, the blending of hydrogen in natural gas pipelines." The bill also would have imposed hydrogen leakage, monitoring, reporting, verification, detection, and repair requirements on pipelines receiving federal financial support under the bill.

PHMSA officials stated in 2022 that the agency was "taking a look at" revising its regulations for hydrogen pipelines but that "research ... needs to be done, we need to know more" to ensure that any potential future changes to its regulations appropriately address risks to hydrogen pipeline safety.¹⁴³ In 2024, PHMSA's acting administrator testified that research on hydrogen pipeline transportation was "necessary and timely as we look towards ... varying hydrogen blending of natural gas pipelines ... which may involve additional rulemaking efforts at PHMSA."¹⁴⁴ Some stakeholders have questioned whether new hydrogen pipeline projects, especially blending projects, should be permitted while PHMSA's existing regulations are being reexamined. As hydrogen infrastructure research, development, and deployment continues, the adequacy of PHMSA's hydrogen pipeline safety regulation may be an issue for Congress.

Special Permits

If a pipeline operator believes unique circumstances would make it impracticable or inappropriate to comply with PHMSA's pipeline safety regulations, the operator may apply to the agency for a special permit to waive or modify compliance. By statute, PHMSA is authorized to "waive compliance with any part of an applicable standard ... with respect to such facility on terms the Secretary [of Transportation] considers appropriate if the Secretary determines that the waiver is not inconsistent with pipeline safety."¹⁴⁵ PHMSA's website lists 135 special permits (formerly called waivers) for pipelines dating back to 1976.¹⁴⁶ PHMSA issued 18 such permits in 2023, all for natural gas transmission pipelines. The agency did not issue any special permits in 2024 or in the first quarter of 2025. PHMSA has not denied a pipeline special permit since 2019.¹⁴⁷

In 2021, GAO published a report reviewing PHMSA's oversight of the Keystone Pipeline, which had experienced several spills while operating under a special permit.¹⁴⁸ The pipeline's special permit, issued in 2007, allowed it to operate at a pressure level of 80% of its specified minimum yield strength (SMYS) rather than the standard limit of 72% of SMYS.¹⁴⁹ The GAO report identified shortcomings in PHMSA's administration of special permits and stated that PHMSA was "establishing a process to more formally document and track the safety and compliance of all special permits."¹⁵⁰ However, PHMSA's special permits continued to be an issue of concern after the December 2022 oil spill near Washington, KS, again from the Keystone Pipeline, which released an estimated 14,000 barrels of crude oil and impacted Mill Creek.¹⁵¹ Some in Congress and other stakeholders questioned PHMSA's issuance and enforcement of the Keystone Pipeline special permit, and the agency's use of such permits in general.¹⁵²

Following the GAO report, PHMSA commissioned Oak Ridge National Laboratory "to assess the overall effectiveness of its pipeline special permit program."¹⁵³ The Oak Ridge report, issued in 2023, concluded that "the enforcement history for special permit pipeline segments is generally positive," and that "based on OPS accident records, the special permit process has not resulted in a reduction in safety of special permit segments."¹⁵⁴ However, the report recommended several changes to improve PHMSA's administration of pipeline special permits, such as establishing an approved standard operating procedure for the special permit process, consistent procedures for special permit compliance oversight, and sunset provisions for special permits.¹⁵⁵ Congress may examine PHMSA's implementation of these recommendations and its oversight and enforcement of existing special permits.

Outdated LNG Safety Standards

The adequacy of PHMSA's minimum safety standards for LNG facilities (49 C.F.R. §193) has become a concern in Congress due to growth in U.S. LNG infrastructure and recent safety incidents.¹⁵⁶ Although PHMSA has no siting authority, FERC requires compliance with PHMSA's regulations for the siting and operation of LNG marine terminals for import or export.¹⁵⁷ In August 2020, GAO published a study of U.S. LNG exports that examined PHMSA's regulation of LNG terminal safety, among other topics. The study reported,

PHMSA's Part 193 regulations for permitting LNG export facilities, last revised in 2015, incorporate nine technical standards that, according to a PHMSA document, are the basis for FERC's safety review of LNG export facilities. Eight of the nine incorporated standards are outdated.¹⁵⁸

The PIPES Act of 2020 subsequently required PHMSA to review its minimum LNG operating and maintenance standards and, based on its review, to update its standards for "large-scale liquefied natural gas facilities (other than peak shaving facilities) to provide for a risk-based regulatory approach for such facilities" (Section 110a).¹⁵⁹ PHMSA was given a three-year deadline from enactment to complete these tasks.

The issue of outdated LNG facility standards initially drew scrutiny after the 2018 partial shutdown of the Sabine Pass LNG terminal in Cameron Parish, TX, due to cracks found in LNG storage tanks that resulted in leaking LNG.¹⁶⁰ This incident was followed by the June 8, 2022, accident at the Freeport LNG export terminal. In the latter incident, a piping failure caused a rapid release of methane, forming a flammable vapor cloud that subsequently exploded as a massive fireball.¹⁶¹ Although no injuries were reported, the incident caused significant damage to adjacent piping, electrical systems, and other facility infrastructure. The LNG terminal was forced to shut down to make repairs and conduct safety recommissioning, temporarily halting approximately 20% of U.S. LNG exports. Freeport LNG was able to resume full operation in March 2023, approximately eight months after the accident.¹⁶² In the wake of the Freeport accident, pipeline safety advocates and community stakeholders called for greater urgency in updating PHMSA's LNG safety requirements.¹⁶³

The PHMSA Deputy Administrator testified in March 2023 that the agency's updated LNG rule was a "priority" and that he "hoped to get a proposal this year."¹⁶⁴ According to PHMSA's public tracker for PIPES Act rulemakings, as of January 2025, the agency expected to publish a revised LNG safety standard in the Federal Register in February 2026.¹⁶⁵ However, on April 29, 2025, the Secretary of Transportation announced that PHMSA was publishing a new Advance Notice of Proposed Rulemaking (ANPRM) to revisit its LNG safety standards, effectively starting the rulemaking process from the beginning.¹⁶⁶ When PHMSA promulgates its new regulations, and whether the revisions to its regulations appropriately incorporate the newest industry standards to reduce LNG safety risks, may be oversight issues for Congress.

Class Location Requirements

PHMSA's safety regulations for natural gas pipelines use "class location" as a method to differentiate risk to the public based on the population density adjacent to a pipeline.¹⁶⁷

Locations along gas pipelines are divided into classes from 1 (rural) to 4 (densely populated) and are based upon the number of buildings or dwellings for human occupancy. Allowable pipe stresses ... decrease as class location increases from Class 1 to Class 4 locations.¹⁶⁸

In October 2020, PHMSA published an NPRM to amend its safety regulations for natural gas transmission pipelines that experience a change in class location due to changes in population density.

Under the existing regulations, pipeline segments located in areas where the population density has significantly increased must perform one of the following actions: Reduce the pressure of the pipeline segment, pressure test the pipeline segment to higher standards, or replace the pipeline segment. This proposed rule would add an alternative set of requirements operators could use, based on implementing integrity management principles and pipe eligibility criteria, to manage certain pipeline segments where the class location has changed.¹⁶⁹

In March 2024, PHMSA convened its Gas Pipeline Advisory Committee to discuss its class location NPRM and recommend approval or modifications to technical aspects of the rule.¹⁷⁰

According to PHMSA, pipeline operators assert "that performing integrity management measures on pipelines where class locations have changed due to population increases would be an equally safe but less costly alternative to the current requirements."¹⁷¹ Pipeline safety advocates have also stated their support for PHMSA to "finalize the rule without major departures from its original intent."¹⁷² However, as of April 2025, PHMSA had not published a final rule. On April 29, 2025, the Secretary of Transportation announced that finalizing PHMSA's pipeline class location change requirements would be a top priority for the agency.¹⁷³ The timing and nature of PHMSA's updated class location regulations, and whether they strike a proper balance between operator efficiency and public safety, may be oversight issues for Congress.

Pipeline Safety Research, Development, and Demonstration

Congress provides PHMSA with funding for pipeline safety-related research and development. According to PHMSA, the agency "conducts and supports research to support regulatory and enforcement activities and to provide the technical and analytical foundation necessary for planning, evaluating, and implementing the pipeline safety program."¹⁷⁴ As of April 30, 2025, PHSMA's database listed 61 active projects supported by approximately $42.4 million in agency funding.¹⁷⁵

In addition to R&D activities funded by PHMSA, the PIPES Act of 2020 included provisions allowing PHMSA to "establish and carry out limited safety-enhancing testing programs to evaluate innovative technologies and operational practices" for natural gas and hazardous liquid pipeline facilities implemented by pipeline operators (§104). In February 2002, PHMSA published in the Federal Register a notice outlining how the agency would review and process Pipeline Safety Enhancement Program (PSEP) applications by pipeline owners and operators, establishing a three-year time limit for the duration of a PSEP pilot project, and setting an application deadline of December 21, 2023.¹⁷⁶ However, according to March 2023 hearing testimony from pipeline industry representatives, no operator had participated in the PSEP technology pilot program because, in their view, PHMSA did not allow sufficient time for the program to operate and imposed excessive administrative and review requirements on the PSEP applications.¹⁷⁷ At the same hearing, the PHMSA Acting Administrator testified that a high standard of safety review is necessary because PSEP projects have safety implications for the public.¹⁷⁸ He also testified that environmental review is mandated under the National Environmental Policy Act (NEPA) but that it is a "common goal" to make the program more efficient.¹⁷⁹

Apart from PHMSA's R&D activities, Congress has funded pipeline safety-related research through DOE. For example, DOE's Hydrogen Program funded a study from 2020 to 2022 by Sandia National Laboratories on hydrogen blending in natural gas pipelines; the study examined, among other things, hydrogen-induced degradation of distribution piping and gaps in related safety codes and standards.¹⁸⁰ In addition, DOE's Office of Fossil Energy and Carbon Management, through its Carbon Transport program and in collaboration with PHMSA and other federal agencies, works "to ensure a safe and reliable CO₂ transport network that supports the deployment of carbon capture, utilization, and storage (CCUS) and carbon dioxide removal (CDR)."¹⁸¹

The Next Generation Pipelines Research and Development Act (H.R. 2613), which was ordered to be reported on April 29, 2025, by the House Committee on Science, Space, and Technology, Subcommittee on Energy, would require the DOE, in coordination with PHMSA, to establish a new initiative to fund

demonstration projects on low- to mid-technology readiness level subjects ... applicable to pipelines and associated infrastructure, including liquefied natural gas facilities and underground and above ground gas and liquid fuel storage facilities; and ... development of next generation pipeline systems, components, and related technologies (§4(a)).

Focus areas under the initiative would include advanced leak detection and mitigation, novel materials, technologies and methods for retrofitting existing pipelines, advanced sensors, and technologies and methods to reduce potential environmental impacts, among others. The initiative would prioritize a diverse mix of commodities, including gas and liquid hydrocarbons, carbon dioxide, hydrogen, and hydrogen blends.

As the programs above indicate, Congress has supported ongoing initiatives within PHMSA, DOE, and the pipeline industry, to develop and deploy new pipeline safety technologies and operating practices. Budgetary and legislative proposals in the 119^th Congress could expand these initiatives. Ensuring that these programs are implemented and coordinated effectively among the various entities involved may require additional congressional oversight and direction.

Pipeline Repair Criteria

In 2022, PHMSA published a final rule including, among other things, updated repair criteria for gas transmission pipelines in HCAs and new repair criteria for pipelines outside HCAs.¹⁸² The final rule updated repair criteria for HCAs to address additional types of pipeline defects, including crack anomalies, corrosion metal loss, and mechanical damage defects. PHMSA's intention was to "provide greater assurance that operators will repair injurious anomalies and defects before those defects grow to a size that causes a leak or rupture."¹⁸³ The rule also established explicit repair criteria for non-HCA pipelines, which previously were subject only to general requirements for repair. However, on August 16, 2024, in a challenge to the rule brought by the Interstate Natural Gas Association of America (INGAA), the United States Court of Appeals for the District of Columbia Circuit vacated some of the repair criteria in the final rule, as well as certain other provisions.¹⁸⁴

In January 2025, PHMSA issued correcting amendments to its final rule, removing several vacated provisions while retaining the rest of the rule.¹⁸⁵ On April 29, 2025, the Secretary of Transportation announced that PHMSA would be issuing an ANPRM addressing both hazardous liquid and gas transmission pipeline repair criteria "to modernize pipeline repair requirements to improve safety and efficiency."¹⁸⁶ How PHMSA may revisit its gas transmission pipeline repair criteria, or consider new repair criteria for hazardous liquids pipelines, may be an oversight issue for Congress.

Conclusion

Government and industry have taken numerous steps to improve pipeline, natural gas storage, and LNG infrastructure safety over the past 10 years. Nonetheless, major oil and natural gas pipeline accidents and security incidents continue to occur. Congress and various stakeholders have called for additional regulatory measures to reduce the likelihood of future failures. Recent PHMSA reauthorizations have included expansive pipeline safety mandates, such as requirements for the agency to update its LNG safety standards, significantly increase inspector staffing, and account for the climate impacts of methane leaks. Congress may consider new regulatory mandates for PHMSA or may impose new requirements directly on the pipeline industry. However, significant changes to pipeline safety regulation are being implemented, and certain rulemakings remain outstanding, so their effects on pipeline safety have yet to be determined. The emergence of new safety risks from the development of carbon dioxide and hydrogen pipeline infrastructure raises additional regulatory challenges. As Congress continues its oversight of the federal pipeline safety program, an important focus may be the practical effects of the many changes being made to particular aspects of PHMSA's pipeline safety regulations.

In addition to the specific issues highlighted in this report, Congress may assess how the many elements of U.S. pipeline safety activity fit together in the nation's overall strategy to protect the public and the environment. Pipeline safety necessarily involves various groups: federal and state agencies, tribal governments, pipeline associations, large and small pipeline operators, local communities, and other interest groups. Reviewing how these groups work together to achieve common goals or resolve conflicting approaches could be an overarching concern for Congress.

Footnotes