(a) Regulations in this subpart apply only to Hilcorp Alaska LLC (Hilcorp) and those persons it authorizes or funds to conduct activities on its behalf for the taking of marine mammals in Cook Inlet, Alaska, and that occurs incidental to the activities described in paragraph (c) of this section. Requirements imposed on Hilcorp must be implemented by those persons it authorizes or funds to conduct activities on its behalf.

(b) The incidental taking of marine mammals by Hilcorp may be authorized in a letter of authorization (LOA) only if it occurs within in Cook Inlet, Alaska.

(c) The taking of marine mammals by Hilcorp is only authorized if it occurs incidental to the use of tugs towing, holding, or positioning a jack-up rig, impact pile driving, and pipeline installation and/or replacement involving anchor handling and/or pipe pulling.

Regulations in this subpart are effective from February 20, 2026, through February 19, 2031.

Under an LOA issued pursuant to §§ 217.106 of this chapter and 217.166, the holder of the LOA (hereinafter “Hilcorp”) may incidentally, but not intentionally, take marine mammals within the specified geographical region described in § 217.160(b) by harassment associated with the specified activities provided they are in compliance with all terms, conditions, and requirements of the regulations in this subpart and the applicable LOA.

Except for the takings permitted in § 217.162 and authorized by an LOA issued under §§ 216.106 of this chapter and 217.166, it is unlawful for any person to do any of the following in connection with the specified activities:

(a) Violate or fail to comply with the terms, conditions, and requirements of this subpart or an LOA issued under this subpart or an LOA issued under §§ 216.106 of this chapter and 217.166;

(b) Take any marine mammal not specified in such LOA;

(c) Take any marine mammal specified in such LOA in any manner other than specified;

(d) Take a marine mammal should NMFS withdraw or suspend such LOA; or

(e) Take a marine mammal specified in such LOA after NMFS determines such taking results in an unmitigable adverse impact on the species or stock of such marine mammal for taking for subsistence uses.

When conducting the specified activities identified in § 217.160(c), Hilcorp must implement the mitigation measures contained in this section and any LOA issued under §§ 216.106 of this chapter and 217.166 unless implementing the mitigation measure would create a risk to human safety or cause pile instability or refusal. These mitigation measures include, but are not limited to:

(a) A copy of any issued LOA should be in the possession of Hilcorp, its designees, and work crew personnel operating under the authority of the issued LOA.

(b) Hilcorp must coordinate with local Tribes as described in its Stakeholder Engagement Plan, notify the communities of any changes in the operation, and take action to avoid or mitigate impacts to subsistence harvests.

(c) Tug boat and pile driving supervisors and crews, the monitoring team, and relevant Hilcorp staff must be trained prior to the start of all activities so that responsibilities, communication procedures, mitigation measures, monitoring protocols, and operational procedures are clearly understood. New personnel joining during the project must be trained prior to commencing work.

(d) Hilcorp must implement clearance and shutdown zones with radial distances as identified in any LOA issued under §§ 216.106 of this chapter and 217.166.

(e) Pre-start clearance monitoring.

(1) Prior to initiating any activity or resuming those activities after a 30-minute lapse (e.g., pauses between intermittent pile driving), Hilcorp must conduct monitoring of the clearance zones 30 minutes prior to commencing activities identified in § 217.160(c) (i.e., pre-start clearance monitoring).

(2) Except for tugs towing a jack-up rig, activities may commence or resume if, following 30 minutes of observation of the clearance zone, it is determined by a protected species observer (PSO) that the clearance zones are clear of marine mammals.

(3) Should a marine mammal be within the clearance zone during the clearance monitoring period, the activity (except for tugs under tow if tidal restrictions necessitate) must not commence or resume until any animal has left the clearance zone and is on a path away from the clearance zone or at least 30 minutes has elapsed for all baleen whale species and Cook Inlet Beluga Whales (CIBWs) without subsequent detection, or 15 minutes has elapsed without subsequent detection for all other species.

(f) Pile driving at the Tyonek Platform may only occur from November 15 through April 15.

(g) Hilcorp must cease all pile driving activities, including soft starts, if a marine mammal is observed entering or within the shutdown zone. Should safety or pile instability or refusal concerns prevent a shutdown, pile driving may continue only until the current segment of the pile is driven; no additional sections of pile or additional piles may be driven until a PSO has determined that the clearance zones are clear of marine mammals.

(1) If pile driving is halted or delayed due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily left and is visually confirmed to be beyond the shutdown zone or at least 30 minutes has elapsed for all baleen whale species and CIBWs without subsequent detection or 15 minutes has elapsed without subsequent detection for all other species.

(2) If during pile driving, a PSO can no longer effectively monitor the entirety of the corresponding shutdown zone due to environmental conditions (e.g., fog, rain, wind), pile driving may continue only until the current segment of the pile is driven. No additional sections of pile or additional piles may be driven until conditions improve such that the shutdown zone can be effectively monitored. If the shutdown zone cannot be monitored for more than 15 minutes, the entire zone must be cleared again for 30 minutes prior to reinitiating pile driving.

(h) Hilcorp must use soft-start techniques when impact pile driving. Should safety or pile instability/refusal concerns arise during a soft start wherein this process cannot be met, Hilcorp must use the minimum amount of energy practicable. Prior to soft-start beginning, the operator must receive confirmation from the PSO that the clearance zone is clear of any marine mammals.

(i) For transportation of a jack-up rig to or from the Tyonek platform, in addition to PSOs stationed on the rig during towing, an additional PSO must be stationed on the Tyonek Platform to monitor for marine mammals. The PSO should be on watch for at least 1 hour before tugs are expected to arrive (scheduled to approach the estimated 120-dB isopleth).

(j) Unless deviation is necessary to maintain safe maneuvering speed and justified because the vessel is in an area where oceanographic, hydrographic, and/or meteorological conditions severely restrict the maneuverability of the vessel; an emergency situation presents a threat to the health, safety, life of a person; or a vessel is actively engaged in emergency rescue or response duties, including vessel-in-distress or environmental crisis response, Hilcorp must:

(1) Maneuver tugs engaged in towing, holding, or positioning a jack-up rig, and anchor handling and pipe pulling activities such that they maintain a consistent speed (approximately 4 knots [kt; 7 kilometers (km)/hr]) and avoid multiple changes of speed and direction to make the course of the vessels as predictable as possible to marine mammals in the surrounding environment, characteristics that are expected to be associated with a lower likelihood of disturbance;

(2) Not actively approach a marine mammal purposefully and must adhere to NOAA Alaska Region Marine Mammal Viewing Guidelines;

(3) Reduce vessel speed to < 9 km/hr (5 kt) when within 274 meters (m; 300 yards) of any whale, reduce speed to 18.5 km/hr (10 kt) or less when weather conditions reduce visibility to 1.6 km (1 mile [mi]) or less, avoid multiple changes in direction and speed when within 274 m (300 yards) of any whale, and place the engine in neutral if a whale is approaching within 91 m (100 yards) of a vessel;

(4) Maintain a distance of at least 2.4 km from the Mean Lower Low Water line of the Susitna River Delta (Beluga River to the Little Susitna River) between April 15 and November 15; and

(5) Maintain a watch for marine mammals while underway and check water immediately adjacent to the vessel prior to engaging propellers; should a marine mammal be observed near propellers and it is determined that interaction is possible, delay engaging propellers.

(k) Hilcorp must maintain clean, taught lines in the water such that no lines are in the water unless both ends are under tension and affixed to vessels or gear.

Hilcorp must implement the following monitoring and reporting measures:

(a) Monitoring must be conducted by NMFS-approved PSOs during all activities for which take is authorized, in accordance with Hilcorp's Marine Mammal Monitoring and Mitigation Plan (which is included in appendix A of Hilcorp's application). PSOs must be independent of the activity contractor (e.g., employed by a subcontractor) and have no other assigned tasks during monitoring duties.

(b) A lead PSO must be designated for all specified activities. The lead PSO must have prior experience performing the duties of a PSO during in-water activities pursuant to a NMFS-issued incidental take authorization or letter of concurrence.

(c) PSOs must monitor for marine mammals from the best available vantage point, ideally an elevated stable platform from which the PSO has an unobstructed 360-degree view of the water or a total 360-degree view of water between all PSOs on watch. Monitoring must occur from 30 minutes before an activity commences to 30 minutes after the activity ceases.

(d) PSOs must use a combination of equipment to scan the appropriate monitoring area and to identify the relevant mitigation distance from an activity, including the naked eye, binoculars (minimum 7x50), and night vision devices for low light and nighttime operations.

(e) PSOs must be in communication with all rig or vessel captains via VHF radio and/or cell phones at all times and alert rig or vessel captains to all marine mammal sightings relative to the vessel location.

(f) PSOs may not work in shifts lasting more than 4 hours without a minimum of 1-hour break and may not be on watch more than 12 hours in a 24-hour period.

(g) Hilcorp must notify NMFS Office of Protected Resources (OPR) at least 48 hours prior to the start of the specified activities each year.

(h) Hilcorp must submit interim monthly monitoring reports on the 15th day of the month after any specified activities occurred. These reports must include a summary of marine mammal species and behavioral observations, delays, shutdowns, and activities completed during the reporting period. The reports also must include an assessment of the amount of work remaining for the year, in addition to the number of CIBWs observed within estimated Level B harassment zones during activities to date, and any instances where mitigation could not be implemented due to safety or pile instability/refusal concerns.

(i) Hilcorp must submit a draft annual summary monitoring report on all monitoring conducted during each project year which includes final electronic data sheets within 90 calendar days of the completion of marine mammal monitoring or 90 days prior to a requested date of issuance of any future incidental take authorization for projects at the same location, whichever comes first. A draft comprehensive 5-year summary report must also be submitted to NMFS within 90 days of the end of year 5 of the project. The reports must detail the monitoring protocol and summarize the data recorded during monitoring. If no comments are received from NMFS within 30 days of receipt of the draft reports, the report may be considered final. If comments are received, revised reports addressing NMFS comments must be submitted within 30 days after receipt of comments. At a minimum, the reports must contain:

(1) Dates and times (begin and end) of all marine mammal monitoring;

(2) Activities occurring during each daily observation period, including the type of activity (tugs under load with a jack-up rig, pile driving, anchor handling, pipe pulling), the total duration of each type of activity, when nighttime operations occurred (and if they did, whether night vision devices (NVDs) were employed, including which lenses were utilized), and whether towing against the tide was required;

(3) PSO locations during marine mammal monitoring;

(4) Environmental conditions during monitoring periods (at beginning and end of PSO shift and whenever conditions change significantly), Beaufort sea state, and any other relevant weather conditions including cloud cover, fog, sun glare, and overall visibility to the horizon, and estimated observable distance; and

(5) Upon observation of a marine mammal, the following information must be collected and included in the annual and 5-year reports:

(i) Name of the PSO who sighted the animal, observer location, and activity at time of sighting;

(ii) Time of sighting;

(iii) Identification of the animal (e.g., genus/species, lowest possible taxonomic level, or unidentified), PSO confidence in identification, and the composition of the group if there is a mix of species;

(iv) Distances and bearings of each marine mammal observed in relation to the vessel (e.g., tug, pipe lay barge) or pile being driven for each sighting (if pile driving was occurring at time of sighting);

(v) Estimated number of animals (min/max/best);

(vi) Estimated number of animals by cohort (adults, juveniles, neonates, group composition, etc.);

(vii) Animal's closest point of approach and estimated time spent within the harassment zone;

(viii) Description of any marine mammal behavioral observations (e.g., observed behaviors such as feeding or traveling), including an assessment of behavioral responses to the activity (e.g., no response or changes in behavioral state such as ceasing feeding, changing direction, flushing, or breaching);

(ix) Detailed information about any implementation of any mitigation (e.g., shutdowns and delays), a description of specific actions that ensued, and resulting changes in the behavior of the animal, if any;

(x) All PSO datasheets and raw sightings data in electronic spreadsheet format; and

(xi) Any instances where mitigation could not be implemented due to safety or pile instability/refusal concerns.

(j) In the event that personnel involved in Hilcorp's activities discover an injured or dead marine mammal, Hilcorp must report the incident to NMFS OPR and the Alaska Regional Stranding Network as soon as feasible. If the death or injury was caused by a specified activity, Hilcorp must immediately cease the specified activity until NMFS is able to review the circumstances of the incident and determine what, if any, additional measures are appropriate to ensure compliance with the LOA. Hilcorp must not resume their activities until notified by NMFS. The report must include the following information:

(1) Time, date, and location (latitude/longitude) of the first discovery (and updated location information if known and applicable);

(2) Species identification (if known) or description of the animal(s) involved;

(3) Condition of the animal(s) (including carcass condition if the animal is dead);

(4) Observed behaviors of the animal(s), if alive;

(5) If available, photographs or video footage of the animal(s); and

(6) General circumstances under which the animal was discovered.

(a) To incidentally take marine mammals pursuant to this subpart, Hilcorp must apply for and obtain an LOA.

(b) An LOA, unless suspended or revoked, may be effective for a period of time not to exceed the effective dates of this subpart in § 217.161.

(c) In the event Hilcorp proposes projected changes to the activity or to mitigation and monitoring measures required by an LOA, Hilcorp must request and obtain a modification of the LOA as described in § 217.167.

(d) The LOA must set forth the following information:

(1) Permissible methods of incidental taking;

(2) Means of effecting the least practicable adverse impact (i.e., mitigation) on the species, its habitat, and on the availability of the species for subsistence uses; and

(3) Requirements for monitoring and reporting.

(e) Issuance of the LOA should be based on a determination that the level of taking will be consistent with the findings made for the total taking allowable under this subpart.

(f) Notice of issuance or denial of an LOA should be published in the Federal Register within 30 days of a determination.

(a) An LOA issued under §§ 216.106 of this chapter and 217.166 for the specified activities may be modified upon request by Hilcorp, provided that:

(1) The changes to the activity or the mitigation, monitoring, or reporting does not change the findings made pursuant to this subpart and do not result in more than a minor change in the total estimated number of takes (or distribution by species or stock or years); and

(2) NMFS determines that Hilcorp implemented the mitigation, monitoring, and reporting measures required by the LOA for which modification is requested.

(b) An LOA issued under §§ 216.106 of this chapter and 217.166 may be modified at NMFS' initiation if:

(1) Doing so creates a reasonable likelihood of more effectively accomplishing the goals of the mitigation and monitoring measures; or

(2) NMFS determines that an emergency exists that poses a significant risk to the well-being of the species or stocks of marine mammals specified in an LOA issued pursuant to §§ 216.106 of this chapter and 217.166, in which case, the LOA may be modified without prior notice or opportunity for public comment; however, notification will be published in the Federal Register within 30 days of the action.

(c) If the modifications to the specified activities, mitigation, monitoring, or reporting measures are substantial, NMFS shall publish a notice of proposed LOA in the Federal Register and solicit public comment prior to making a determination on issuance.

(d) Possible sources of data that could contribute to a decision to modify the LOA include, but are not limited to:

(1) Results from Hilcorp's monitoring;

(2) Results from other marine mammal and/or sound research or studies; and

(3) Any information that reveals marine mammals may have been taken in a manner, extent or number not authorized by this subpart or subsequent LOAs.