SUPPLEMENTARY INFORMATION:

I. Table of Abbreviations

BNM Broadcast Notice to Mariners

CFR Code of Federal Regulations

COTP Captain of the Port, Boston

DHS Department of Homeland Security

DMS Degrees, Minutes, Seconds (Geodetic coordinate format)

DP Dynamic Positioning

DWP Deepwater Port

EIR Environmental Impact Report

EIS Environmental Impact Statement

ENC Electronic Navigational Chart

ESA Endangered Species Act

FM Frequency Modulation

FR Federal Register

LNG Liquid Natural Gas

LNM Local Notice to Mariners

MARAD Maritime Administration (U.S. Department of Transportation)

MMPA Marine Mammal Protection Act

NEPA National Environmental Policy Act of 1969

NMFS National Marine Fisheries Service (NOAA Fisheries)

NOAA National Oceanic and Atmospheric Administration

NPRM Notice of proposed rulemaking

TFR Temporary Final Rule

PLEM Pipeline End Manifold

PSO Protected Species Observer

RFA Regulatory Flexibility Act of 1980

ROV Remotely Operated Vehicle

SRV Shuttle and Regasification Vessel

STL Submerged Turret Loading

MA Massachusetts

§ Section

U.S.C. United States Code

USACE United States Army Corps of Engineers

USCG United States Coast Guard

UTM Universal Transverse Mercator (Grid coordinate system)

VHF Very High Frequency

WGS 84 World Geodetic System 1984 (Geodetic reference system)

II. Background and Authority

On August 7, 2026, Neptune LNG LLC notified the Coast Guard that the Maritime Administration (MARAD) had granted final approval for the decommissioning of the Neptune LNG LLC Deepwater Port in Massachusetts Bay, located approximately 22 miles northeast of Boston, Massachusetts. The project is extensive and will require specialized equipment utilized by divers working on the sea floor. The planned physical removal framework involves taking out two submerged turret loading buoys, three transition manifolds, 16 wire rope and chain mooring lines and connecting infrastructure while partially abandoning buried pipeline in place. On September 23, 2026, the Coast Guard published a notice of proposed rulemaking (NPRM) titled Safety Zone; Massachusetts Bay, Boston, MA (91 FR 60347). In that NPRM, we stated why we issued the NPRM and invited comments on our proposed regulatory action related to this project. We ( printed page 73143) received one comment during the comment period that ended October 23, 2026.

The COTP has determined that this rule, which is published under the authority of 46 U.S.C. 70034, is necessary to protect personnel, vessels, and the marine environment from potential hazards associated with project. No vessel or person will be permitted to enter the safety zone without obtaining permission from the COTP or their designated representative.

III. Discussion of Comments

As noted above, the Coast Guard received one comment on the NPRM published on September 23, 2026 (91 FR 60247). The comment requested detailed clarifications regarding: (1) the geographic scope and reconciliation of work site coordinates; (2) the technical hazard basis for the 500-meter safety zone radius; (3) project environmental authorizations and marine mammal mitigation; (4) subsea infrastructure closeout, seabed clearance surveys, and nautical chart updates; and (5) enforcement, suspension, and potential extension of the safety zone.

The Coast Guard addresses each of these topics below:

1. Geographic Scope, Coordinate Reconciliation, and Movable Exclusion Zones Operational Phasing & Coordinates: The decommissioning campaign is designed as a phased, sequential operation spanning an estimated 146 days of offshore work, except for approximately a three-week period when flushing and flaring activities will take place simultaneously at two locations. During this period, the construction vessels will be located at the transition manifold (approx. posn 42°29′07.17″ N, 70°46′34.74″ W) while the flare/filtration vessel will be positioned at the South Pipeline End Manifold (PLEM) in the vicinity of the South STL Buoy (approx. posn 42°27′20.5″ N, 070°36′07.3″). The coordinate published in the NPRM (42°28′52.1″ N, 070°46′16.9″ W) represented a location in the vicinity of the decommissioning operations across the 2.3-mile spread between the North STL Buoy, the South STL Buoy, and the HubLine hot-tap tie-in location.

• Reconciling Distance: We acknowledge that the two STL buoys are located 2.3 miles apart (as documented in Section 2.7 of the Neptune Final Decommissioning Plan). To protect all work locations—including the North Buoy, the South Buoy, and the pipeline tie-in at the Algonquin HubLine “hot-tap” connection—without unnecessarily restricting commercial navigation and fishing across a static 2.3-mile corridor, the Coast Guard is clarifying that this is a moving safety zone.
• Movable Zone Application: The regulatory text in the Temporary Final Rule has been clarified to establish a 500-meter moving safety zone centered on the primary construction vessel or vessels. As work shifts from the North Buoy to the South Buoy and the hot-tap assembly, the safety zones will move with the active construction vessels. Again, as discussed above, we anticipate only one safety zone being enforced except for a three-week period where there will be two active zones. The Captain of the Port (COTP) Boston will make notification of the exact active location and the name of the primary construction vessel at that location in advance of each enforcement period to the local maritime community through the Local Notice to Mariners (LNM) Northeast District and will issue a Broadcast Notice to Mariners (BNM) via marine channel 16 (VHF-FM) as soon as practicable in response to an emergency. The LNM has historically been the primary means for disseminating information concerning aids to navigation, hazards to navigation, and other marine information of interest to mariners on the waters of the United States. The LNM is available online and can be found at its dedicated website www.navcen.uscg.gov. Notices are published weekly. Interested parties may subscribe to receive email updates at navcen.uscg.gov/​subscribe-email-rss-feeds. The Coast Guard believes the use of the LNM to be the most efficient means to distribute information concerning locations and enforcement periods for these moving safety zones. The Coast Guard will issue a BNM via marine channel 16 (VHF-FM) as soon as practicable in response to an emergency or hazardous condition. The Coast Guard now offers an online subscription service in addition to the standard VHF BNM broadcasts which, traditionally, was the only method to receive this vital navigational information. Mariners may now use a subscription service to plan for underway periods and can receive updates to navigational hazards in near-real-time without waiting on scheduled VHF broadcasts. Sign up to receive BNMs via email for your waterway at www.navcen.uscg.gov/​subscribe-email-rss-feeds.

2. Technical and Operational Basis for the 500-Meter Radius: The 500-meter (approx. 547-yard) radius was determined through an operational risk assessment in consultation with the Maritime Administration (MARAD) and the primary marine contractors. The 500-meter radius is also consistent with other rulemakings used during the construction of the deepwater port and during its operation as cited in 33 CFR 165.117 Regulated Navigation Areas, Safety and Security Zones: Deepwater Ports, USCG Northeast District. It represents the minimum necessary envelope to mitigate the following hazards:

• Vessel Positioning Failures: Heavy operations will utilize large construction vessels. A 500-meter radius provides a safe “drift-off” or “drive-off” buffer in the event of a Dynamic Positioning system failure, allowing time for emergency recovery before colliding with external vessels.
• Heavy Lifts and Tensioned Moorings: Recovering 16 massive catenary mooring lines (composed of 150m of spiral strand wire rope and heavy chain) and the 169,400 kg STL buoys involves high-tension shears and heavy crane lifts. This introduces significant snap-back, load-drop, and dropped-object risks extending well beyond the immediate hull profile.
• Diver and ROV Safety: Saturation diving and Work-Class Remotely Operated Vehicles (ROVs) will be deployed continuously. Protecting diver umbilicals and decompression profiles from vessel wake, propeller wash, and entangling drift traffic requires a strict 500-meter exclusion zone.

3. Environmental Authorizations and Protected Species Mitigation: The Coast Guard has analyzed this rule under Department of Homeland Security Directive 023-01, Rev. 1, associated implementing instructions, and Environmental Planning COMDTINST 5090.1 (series), which guide the Coast Guard's compliance with the National Environmental Policy Act of 1969 (42 U.S.C. 4321-4370f). The Coast Guard has determined that the action is one of a category of actions that do not individually or cumulatively have a significant effect on the human environment. This rule establishes a safety zone around subsea demolition operations to protect life, property, and the marine environment and is categorically excluded from further review under paragraph L60(a) of Appendix A, Table 1 of DHS Instruction Manual 023-01-001-01, Rev. 1. A Record of Environmental Consideration supporting this determination is available in the subject docket. For instructions on locating the docket, see the ADDRESSES section of the preamble.

The Coast Guard is also aware that all operations are authorized and governed by federal environmental requirements:

• MARAD & NEPA Approval: The decommissioning is authorized under the Deepwater Port Act of 1974 license ( printed page 73144) conditions, formally approved by the Maritime Administrator, Capt. Stephen M. Carmel, on July 20, 2026. MARAD determined that the environmental impacts are consistent with the original Final EIS/EIR, meaning further NEPA review is not required.
• Protected Species Mitigation: Operations must strictly comply with the Endangered Species Act (Section 7) Biological Opinion and Marine Mammal Protection Act (MMPA) requirements issued by National Marine Fisheries Service (NMFS). This includes:

1. Stationing certified Protected Species Observers (PSOs) onboard with full stop-work authority.

2. Mandatory 10-knot vessel speed caps within designated North Atlantic right whale management areas.

3. A seasonal work window: To avoid adverse impacts on Atlantic cod spawning aggregations, no offshore decommissioning activities will occur between October 1 and January 31.

4. Pipeline Isolation, Infrastructure Disposition, and Chart Updates: As an initial matter, the Coast Guard notes that the technical and structural details of subsea closeout, pipeline decommissioning, and permanent seabed configuration are beyond the scope of this rulemaking, which is strictly limited to establishing temporary safety zones for navigation safety during active operations. However, for transparency, the Coast Guard provides the following technical context from the approved decommissioning records including the Final Decommissioning Plan, March 2025 (available in the docket).

• Pipeline Decommissioning: Decommissioning of the 13.2-mile, 24-inch pipeline will strictly follow PHMSA (49 CFR part 192) standards. The pipeline has already been isolated from the Algonquin HubLine, depressurized, purged, and flooded.
• Infrastructure Recovery: The transition manifold, two PLEMs, four tie-in spools, and flexible risers will be completely removed and recovered to shore for recycling or disposal (at authorized facilities such as Jay Cashman Inc. in Quincy, MA).
• Anchors & Mattresses: Consistent with feedback from the Massachusetts Lobstermen's Association and trawlers, the 16 suction caisson anchors will be cut 3 feet below the mudline, capped with biodegradable sand/cement bags, and backfilled with native sediment to restore a flat, trawlable seafloor. Approximately 141 concrete mattresses will be fully recovered to shore.
• Post-Decommissioning Surveys and Charting: Following physical removal, Neptune will conduct high-resolution as-left multibeam bathymetric and side-scan sonar surveys, verified by an ROV. The certified as-left hydrographic surveys will be submitted immediately to the National Oceanic and Atmospheric Administration (NOAA) Office of Coast Survey to update Electronic Navigational Charts (ENCs) and paper nautical charts.

5. Suspension and Extension Protocols:

• Operational Suspensions: Enforcement of the safety zone is strictly tied to active operations. If operations are paused due to weather stand-downs or scheduling delays, the COTP will suspend active enforcement and broadcast this suspension to mariners via the LNM.
• Timeline and Extensions: Under the MARAD approval letter dated July 20, 2026, decommissioning must be completed within two years (by July 20, 2028). This rule will remain effective through September 30, 2027, which should accommodate the possibility of project delays due to unforeseen circumstances. If the project is completed before September 30, 2027, enforcement of the safety zone will be suspended, and notice will be provided via the LNM. The Coast Guard Northeast District LNM can be found at: www.navcen.uscg.gov/​maritime-safety-information.
• If additional delays occur requiring an extension of the safety zone past September 30, 2027, the Coast Guard will issue a new public notice to extend the regulation.

IV. Discussion of Changes, and the Rule

There are changes in the regulatory text of this rule from the proposed rule in the NPRM.

The regulatory text in this rule has been amended to clarify that the 500-meter safety zone will now center on the active decommissioning primary construction vessel or vessels conducting the decommissioning operations. As work shifts in the area from the vicinity of the North Buoy to the South Buoy and the hot-tap assembly, or at two locations simultaneously, the safety zones will move with the primary vessels. The COTP will make notification of the exact location and the name of the primary construction vessel at that location in advance of each enforcement period to the local maritime community through the LNM and will issue a BNM via marine channel 16 (VHF-FM) as soon as practicable in response to an emergency.

This rule establishes moving safety zones from 11:59 p.m. February 28, 2027, through 8 a.m. September 30, 2027. The safety zones will cover all the navigable waters of the Massachusetts Bay in a 500-meter radius of the primary construction vessels position operating in the approximately 22 miles northeast of Boston, MA (42°28′52.1″ N, 070°46′16.9″ W). The COTP will make notification of the exact location and the name of the primary construction vessel at that location in advance of each enforcement period to the local maritime community through the LNM and will issue a BNM via marine channel 16 (VHF-FM) as soon as practicable in response to an emergency. No vessel or person will be permitted to enter the moving safety zones without obtaining permission from the COTP or a designated representative.

This rule will remain in effect through September 30, 2027, which should accommodate the possibility of project delays due to unforeseen circumstances. If the project is completed before September 30, 2027, enforcement of the safety zone will be suspended, and notice will be provided via the Local Notice to Mariners.

The Coast Guard Northeast District Local Notice to Mariners can be found at: www.navcen.uscg.gov/​maritime-safety-information.

After considering the comment discussed above, the Coast Guard determined that no additional changes should be made to the regulatory text based on this comment. As written, the Coast Guard believes that the rule ensures consistency, sufficient notice, and improved safety while minimizing impact on vessel transit.

V. Regulatory Analyses

We developed this rule after considering numerous statutes and Executive Orders related to rulemaking. Below we summarize our analyses based on a number of these statutes and Executive Orders.

A. Impact on Small Entities

The Regulatory Flexibility Act of 1980, RFA), 5 U.S.C. 601-612, as amended, requires Federal agencies to consider the potential impact of regulations on small entities during rulemaking. The term “small entities” comprises small businesses, not-for-profit organizations that are independently owned and operated and are not dominant in their fields, and governmental jurisdictions with populations of less than 50,000. Section 605 of the RFA allows an agency to certify a rule, in lieu of preparing an analysis, if the rulemaking is not expected to have a significant economic impact on a substantial number of small entities. ( printed page 73145)

The Coast Guard certifies under 5 U.S.C. 605(b) that this temporary final rule would not have a significant economic impact on a substantial number of small entities for the following reasons. Vessel traffic will be able to safely transit around this regulated area. This regulation will only impact a small area of Massachusetts Bay. In addition, the Coast Guard will issue a Local Notice to Mariners and a Broadcast Notice to Mariners via VHF FM marine channel 16, which will allow small entities to adjust their transit plans, and the rule allows vessels to request permission to enter the regulated area from the COTP.

Under section 213(a) of the Small Business Regulatory Enforcement Fairness Act of 1996 (Pub. L. 104-121), if this rule will affect your small business, organization, or governmental jurisdiction and you have questions, contact the person listed in the FOR FURTHER INFORMATION CONTACT section.

Small businesses may send comments to the Small Business and Agriculture Regulatory Enforcement Ombudsman and the Regional Small Business Regulatory Fairness Boards by calling 1-888-REG-FAIR (1-888-734-3247).

B. Collection of Information

This rule will not call for a new collection of information under the Paperwork Reduction Act of 1995 (44 U.S.C. 3501-3520).

C. Federalism and Indian Tribal Governments

We have analyzed this rule under Executive Order 13132, Federalism, and have determined that it is consistent with the fundamental federalism principles and preemption requirements described in that Order.

Also, this rule does not have tribal implications under Executive Order 13175, Consultation and Coordination with Indian Tribal Governments, because it does not have a substantial direct effect on one or more Indian tribes, on the relationship between the Federal Government and Indian tribes, or on the distribution of power and responsibilities between the Federal Government and Indian tribes.

E. Unfunded Mandates Reform Act

As required by The Unfunded Mandates Reform Act of 1995 (2 U.S.C. 1531-1538), the Coast Guard certifies that this rule will not result in an annual expenditure of $100,000,000 or more (adjusted for inflation) by a State, local, or tribal government, in the aggregate, or by the private sector.

F. Environment

We have analyzed this rule under Department of Homeland Security Directive 023-01, Rev. 1, associated implementing instructions, and Environmental Planning COMDTINST 5090.1 (series), which guide the Coast Guard in complying with the National Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.), and have determined that this action is one of a category of actions that do not individually or cumulatively have a significant effect on the human environment.

This rule is a safety zone. It is categorically excluded from further review under paragraph L60(a) of Appendix A, Table 1 of DHS Instruction Manual 023-01-001-01, Rev. 1. A Record of Environmental Consideration supporting this determination is available in the docket.

For the reasons discussed in the preamble, the Coast Guard amends 33 CFR part 165 as follows:

91 FR 73142