Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Port of Alaska Modernization Program Phase 2B: Cargo Terminals Replacement Project in Anchorage, Alaska

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 217

[250630-0117]

RIN 0648-BM30

Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Port of Alaska Modernization Program Phase 2B: Cargo Terminals Replacement Project in Anchorage, Alaska

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:

Final rule.

SUMMARY:

NMFS, upon request from the Don Young Port of Alaska (POA), hereby promulgates regulations to govern the taking of marine mammals incidental to the Cargo Terminals Replacement (CTR) project at the existing port facility in Anchorage, Alaska over the course of 5 years. These regulations, which allow for the issuance of a Letter of Authorization (LOA) for the incidental take of marine mammals during the specified activities in the specified geographical region (see Description of the Specified Activities section) during the effective dates of the regulations, prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on marine mammal species or stocks and their habitat, as well as requirements pertaining to the monitoring and reporting of such taking.

DATES:

Effective from March 1, 2026 through February 28, 2031.

ADDRESSES:

Electronic copies of the application and supporting documents, the proposed rule and associated public comments, as well as a list of the references cited in this document, may be obtained online at:

https://www.fisheries.noaa.gov/action/incidental-take-authorization-port-alaskas-construction-activities-port-alaska-modernization.

In case of problems accessing these documents, please call the contact listed below.

FOR FURTHER INFORMATION CONTACT:

Cara Hotchkin, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Purpose of Regulatory Action

These regulations, promulgated under the authority of the Marine Mammal Protection Act (MMPA) (16 U.S.C. 1361

et seq.

), establish a framework for NMFS to authorize the take of marine mammals incidental to construction activities associated with the CTR project (Phase 2B of the POA's Modernization Program) in Anchorage, Alaska.

Legal Authority for the Action

Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs the Secretary of Commerce, as delegated to NMFS, to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region for up to 5 years if, after notice and public comment, the agency makes certain findings and promulgates regulations that set forth permissible methods of taking pursuant to that activity and other means of effecting the “least practicable adverse impact” on the affected species or stocks and their habitat (see Mitigation section), as well as monitoring and reporting requirements.

Summary of Major Provisions Within the Rule

Following is a summary of the major provisions of this rule regarding POA's activities. These measures include:

• Prescribing permissible methods of taking of small numbers of 7 species (10 stocks) of marine mammals by Level B harassment, and for a subset of those (6 species comprising 9 stocks) by Level A harassment, incidental to the CTR project;

• Monitoring of the construction areas to detect the presence of marine mammals before beginning construction activities;

• Establishment of shutdown zones equivalent to the estimated Level B harassment zone for Cook Inlet beluga whales (CIBW);

• Establishment of shutdown zones for other species;

• Use of bubble curtains for all impact and vibratory driving of permanent (72-inch (in) (1.83 meter (m)) piles in more than 3 m of water depth in all months;

• Soft start for impact pile driving to allow marine mammals the opportunity to leave the area prior to beginning impact pile driving at full power; and

• Submittal of monitoring reports, including a summary of marine mammal species and behavioral observations, construction shutdowns or delays, and construction work completed.

Through adaptive management, the regulations will allow NMFS Office of Protected Resources to modify (

e.g.,

remove, revise, or add to) the existing mitigation, monitoring, or reporting measures summarized above and required by the LOA.

Background

The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361

et seq.

) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are promulgated or an incidental harassment authorization is issued.

Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). If such findings are made, NMFS must prescribe permissible methods of taking; other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in shorthand as “mitigation”); and requirements pertaining to the monitoring and reporting of the takings. The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below.

Summary of Request

On January 3, 2023, NMFS received a request from the POA for regulations and a subsequent LOA to take marine mammals incidental to construction activities related to the POA Modernization Program (PAMP) Phase 2B: CTR project at the POA in Anchorage, Alaska. NMFS provided comments on the application on March 3, 2023 and provided additional comments to POA in response to new information on April 20, 2023 and May 18, 2023. After POA submitted a revised application on October 13, 2023 and responded to additional questions sent on December 20, 2023, NMFS determined the application was adequate and complete on February 12, 2024.

On March 4, 2024, we published a notice of receipt (NOR) of application in the

Federal Register

(89 FR 15548),

requesting comments and information during a 30-day public comment period related to the POA's request. We received 1 comment letter from the Center for Biological Diversity (CBD) and considered the comments in that letter during development of the proposed rule. On October 28, 2024, we published the proposed rule in the

Federal Register

(89 FR 85686) and requested comments and information from the public. NMFS reviewed the submitted material and considered it for promulgation of these regulations.

Description of the Specified Activities

The POA, located on Knik Arm in upper Cook Inlet, was constructed primarily in the 1960s and is currently in poor condition and substantially past its initial design life. The CTR project includes construction of two new terminals (T1 and T2), which include planned wharves and access trestles. The two new terminals will be located 140 feet (ft) (42.7 m) seaward of the existing general cargo terminals (T1, T2, and T3). The CTR project also includes demolition of the existing Petroleum, Oil, and Lubricants Terminal 1 (POL1) and T1, T2, and T3. In-water pile installation will include both temporary (24-in (0.61m) or 36-in (0.91 m)) and permanent (72-in (1.83 m)) steel pipe piles by impact and vibratory hammers. Removal of temporary piles (24- or 35-in) and existing structures (16-in (0.41 m) to 42-in (1.07 m) steel pipe piles) will be primarily by cutting; dead-pull and vibratory extraction methods may also be used. Existing piles may also be left standing in their current positions. In-water work associated with the CTR project will include installation of approximately 275 permanent piles and 450 temporary piles and vibratory extraction of approximately 46 temporary piles. Work will occur on approximately 337 nonconsecutive days between the months of March and November in 2026 through 2030. The specified geographical region encompasses the land occupied by the POA, as well as the shoreline and waters extending from the POA across Knik Arm, northeast towards Wasilla, and southwest towards Fire Island and the Little Susitna River delta.

A detailed description of the specified activities is provided in the proposed rule (89 FR 85686, October 28, 2024). Since that time, POA has not modified their planned activities. Please refer to the proposed rule (89 FR 85686) for more information on the specified activities.

Comments and Responses

NMFS published the proposed rule in the

Federal Register

on October 28, 2024 (89 FR 85686), beginning a 30-day comment period. It described, in detail, the POA's specified activities, the marine mammal species that may be affected by the activities, and the anticipated effects on marine mammals. In that document, we requested public input on the request for authorization described therein, our analyses, preliminary determinations, and the proposed regulations and requested that interested persons submit relevant information, suggestions, and comments.

During the 30-day public comment period, NMFS received comments from the POA, the Alaska Department of Fish and Game (ADF&G), the CBD, Friends of Animals, and five anonymous members of the public. After conclusion of the comment period on January 1, 2025, we received an additional comment from Chickaloon Village Traditional Council (CVTC). Our responses to relevant substantive comments are below. We have not responded to comments that failed to raise a significant point for us to consider (

e.g.,

comments that are out of scope of the proposed rule or that call for mitigation, monitoring, or reporting measures already included in the proposed rule). Furthermore, if a comment received was unclear, NMFS does not include it here as it could not determine whether it raised a significant point for NMFS to consider. The comments and recommendations are available online at:

https://www.fisheries.noaa.gov/action/incidental-take-authorization-port-alaskas-construction-activities-port-alaska-modernization.

Please see the comment submissions for full details regarding the recommendations and supporting rationale.

Comment 1:

ADF&G commented that CIBW are “known to travel into Knik Arm to forage, particularly in the months of June through August.” ADF&G suggests that activities taking place in these months should be temporarily halted while CIBW are “in proximity,” and notes that it supports the use of “certified marine mammal observers.”

Response:

NMFS agrees that shutdowns of certain activities when marine mammals enter specified areas where they may be impacted and the use of approved Protected Species Observers (PSO) are appropriate and essential mitigation measures for the POA's activities and are included in the suite of prescribed mitigation measures for these Incidental Take Regulations (ITR). While ADF&G does not define what they mean by “in proximity,” pile driving at the CTR project will be required to temporarily shut down in all months when CIBWs approach or are observed within the modeled Level B harassment isopleths (

see

Mitigation section). We note that CIBW presence in Knik Arm is highest during the months of August through October (McGuire

et al.

2020; Castellote

et al.

2020), rather than June through August as suggested by ADF&G.

Comment 2:

The POA submitted a letter stating that the combined effects of certain proposed mitigation measures, specifically requirements to (1) employ a bubble curtain during vibratory temporary pile driving and extraction during the months of August through October and (2) shut down when CIBWs enter the predicted Level B harassment zone “will create undue hardship” to the CTR project. POA also asserts that these measures offer “no proven added benefit” for CIBW and that additional time required for implementation of these measures will prevent the completion of the CTR project on time, increasing the risk of a critical facility failure. The letter states that the North Extension Stabilization—Phase 1 (NES1) project faced significant delays associated with shutdown requirements during the 2024 construction season due to high CIBW presence. The POA requests that NMFS either (1) remove the requirement to use a bubble curtain during vibratory driving of temporary piles in the months of August through October, or (2) incorporate consideration of frequency sensitivity to its calculations of estimated Level B harassment isopleths. The POA states that use of the bubble curtain would differentially affect frequency content to which CIBW are more sensitive and, therefore, estimated Level B harassment isopleths would be smaller than calculated by NMFS (see Comment 3).

Response:

NMFS agrees, in part, with the POA's comments. The proposed mitigation requirement at issue was for the use of bubble curtains during vibratory driving of temporary piles in the months of historically high CIBW presence (August through October; bubble curtains were not proposed for use in other months for this activity). Other proposed mitigation requirements for CIBWs include shutdown zones equal to the predicted Level B harassment zone and the use of bubble curtains during all impact and vibratory driving of permanent piles in waters deeper than 3 m in all months. Notably, the POA presents practicability concerns regarding the likelihood of

increased operational impacts (

i.e.,

financial costs and potential need for additional construction seasons) associated with delays that may result from increased CIBW presence. These concerns, when considered in conjunction with the relatively lower assumed effectiveness of the proposed requirement to use bubble curtains during vibratory driving, lead to NMFS' determination that the POA provided a compelling justification for modification of the proposed mitigation requirements, as discussed below.

Sightings of CIBW at and around the POA during 2024 were between 53 and 330 percent higher than the prior construction period for the Petroleum and Cement Terminals (PCT) project in 2020-2021 in the months of June, July, and August. Pile driving activities associated with the NES1 project were shut down or delayed for a total of 228.5 hours over the course of the construction season, equivalent to nearly 23 ten-hour workdays. This increase relative to expectations in time lost to shutdowns was due in part to delays in starting the NES1 project that pushed the start of construction from April to the end of May, when CIBW presence is higher. However, NMFS acknowledges that increased occurrence of CIBW at the site during the early summer contributed to unanticipated project delays. Reasons for the increased CIBW presence at and around the POA are uncertain at this time but could include changes to prey availability throughout upper Cook Inlet or other factors and may persist into the time period covered by this rule. NMFS acknowledges the POA's concerns about the time required to deploy bubble curtains around each pile and regarding the effectiveness of bubble curtains at reducing sound energy in the far-field. Previous measurements conducted at POA showed that use of the bubble curtain did not effectively reduce actual distances to the 120 dB RMS threshold due to the prevalence of sound energy below 100 Hz. While use of a bubble curtain effectively reduces the sound pressure level (SPL) any marine mammal in the CTR project area would experience from any sound source, the use of a bubble curtain during vibratory pile driving is not common. Bubble curtains are most effective at reducing the injurious components of impulsive sounds, including sharp rise times and high peak pressures associated with impact pile driving (CALTRANS, 2020). While they can be used to reduce SPLs associated with continuous noise sources, such as vibratory pile driving, the benefits to species, including fishes and marine mammals, are fewer because of the less injurious nature of the sound sources.

The most effective mitigation measure for CIBWs included in these regulations is the requirement to implement a shutdown of pile driving activities at the predicted Level B harassment isopleth during vibratory and impact pile driving. This measure minimizes the potential for disruption of CIBW behavioral patterns by avoiding to the extent practicable exposure to sound exceeding harassment thresholds during pile driving. While bubble curtains effectively reduce vibratory pile driving noise levels at frequencies to which CIBWs are sensitive (

i.e.,

frequencies over 1,000 Hz) (Castellote et al. 2014; Illingworth and Rodkin 2021a) at any given distance, a shutdown upon occurrence of CIBW within the estimated Level B harassment zone is the most effective way of minimizing impacts to CIBW. For other species, while the predicted Level A harassment zones exceed the required shutdown zones during concurrent vibratory driving scenarios, the likelihood of these species approaching to within 165 m of the incident piles during concurrent driving is minimal. As documented by previous measurements of sound propagation in Cook Inlet, broadband sound levels at the predicted Level B harassment isopleth are driven by frequencies below 100 hertz (Hz), which are outside of the range of CIBWs' peak hearing sensitivity, indicating that the predicted Level B harassment zone is likely a conservative estimate for impacts to CIBW. Additionally, as shown by summer 2024 monitoring data and previous monitoring reports from 2020 and 2021, unattenuated vibratory pile driving in the vicinity of the POA does not prevent CIBW from approaching and passing the POA (61N Environmental 2021, 2022a, 2022b, 2025). NMFS, therefore, believes the risk that unattenuated vibratory pile driving would meaningfully impact CIBW behavioral patterns is low.

Given the documented practicability issues that the POA referenced in its comment letter and the other, more effective mitigation measures required, NMFS agrees with the POA's request to remove the requirement for the use of bubble curtains during vibratory installation and extraction of temporary piles in the months of August through October for the CTR project. NMFS has determined, based on the practicability concerns presented by POA and the relatively low effectiveness of this requirement during time periods when fewer CIBW are present at the POA, that the prescribed mitigation measures as modified remain sufficient to effect the least practicable adverse impact on the affected marine mammal stocks.

Comment 3:

The POA stated that calculation of the estimated Level B harassment isopleths should account for the hearing sensitivity of beluga whales. The POA suggested that NMFS apply the weighting functions used in the 2024 Updated Technical Guidance to the analysis of the Level B isopleths to reflect the reduction in sound energy expected at certain frequencies that belugas are sensitive to as a result of employing a bubble curtain during vibratory pile driving of temporary piles.

Response:

As noted by the POA, the estimated Level B harassment distances for sound from pile driving activities are based on unweighted broadband sound levels. However, use of the weighting functions recommended by POA relate specifically to the susceptibility to noise induced hearing loss for different groups of marine mammals and, therefore, are used for evaluation of potential auditory injury (which falls under Level A harassment) or temporary threshold shift (NMFS 2024). Thus, that weighting is not appropriate to consider in evaluating the potential for behavioral harassment (which falls under Level B harassment) as the POA recommends. Beluga hearing measurements indicate they can detect sounds from 4 Hz to 130 kilohertz (kHz) (Southall

et al.

2019) and vibratory pile driving sound is thus within the hearing range of this species. Even assuming use of a broader weighting function that is more appropriate for consideration with behavioral harassment (Southall

et al.

2007), only a minimal reduction would occur (

e.g.,

less than −5 dB weighting at 100 Hz). Therefore, NMFS does not agree with the POA's recommendation to reduce the size of the shutdown zones based on the POA's approximations of beluga hearing sensitivity.

Comment 4:

The CBD asserts that NMFS' small numbers determination is arbitrary, unlawful, unreasonable, and improper. It states that NMFS' determination is based on an unlawful interpretation of what constitutes a small number that is contrary to the plain meaning of the phrase and NMFS failed to consider the species' endangered status.

Response:

NMFS has provided a reasoned approach to small numbers, as described in full in the final rule, “Taking Marine Mammals incidental to Geophysical Surveys Related to Oil and Gas Activities in the Gulf of Mexico” (86 FR 5322, 5438, January 19, 2021). NMFS makes its small numbers findings

based on an analysis of whether the number of individuals authorized to be taken annually from a specified activity is small relative to the most appropriate estimate of stock size. CBD cites

NRDC

v.

Evans,

279 F.Supp. 2d 1129 (N.D. Cal. 2003) to support its position. However, CBD's reading of that case is inaccurate. In

Evans,

the court ruled that the negligible impact determination and the small numbers analysis must be undertaken separately, but the court specifically “does not require defendants to set an absolute numerical limit” for small numbers (

Id.

at 1152). Following that case, NMFS undertook separate small numbers findings from its negligible impact determinations, analyzing in each case whether the numbers were small relative to the stock or population size (the “proportional approach”).

We note that in this final rule, based on the best available scientific information for CIBW occurrence in the CTR project area (

i.e.,

NES1: POA Construction Monitoring 61N Environmental, 2025), the number of estimated takes of CIBWs increased from 90 to 118, amounting to 35.6 percent of the stock if each take accrued to a new individual (table 19). While NMFS typically presumes that each take is of a different individual, in this case, due to the CTR project location and feeding grounds in the upper Arm near Eagle Bay, we expect some individuals could be taken more than once. Thus, the actual number of individuals affected is expected to be fewer than 118 and the maximum annual number of animals taken from this stock is considered small relative to the relevant stock's abundance.

We disagree with CBD's assertion that NMFS' small number determination for CIBWs should consider the status of the species. The argument to establish a small numbers threshold on the basis of stock-specific context is unnecessarily duplicative of the required negligible impact finding, in which relevant biological and contextual factors are considered in conjunction with the number of takes and would conflate the two distinct standards (see

NRDC

v.

Evans,

279 F.Supp. at 1153).

Comment 5:

CBD contends that NMFS's small numbers and negligible impact determinations are arbitrary because NMFS failed to evaluate the finding that noise from tugboats and cargo/tanker vessels are the highest noise threats to CIBWs according to NMFS' Recovery Plan for CIBWs (NMFS, 2016). CBD further states that NMFS failed to account for take from all project activities, including soft starts.

Response:

NMFS' Recovery Plan (NMFS, 2016) ranks noise from tugboats and cargo/tanker vessels as the most important sources that could potentially interfere with CIBW recovery based on signal characteristics and spatio-temporal acoustic footprint. Specifically, NMFS (2016) identified propeller cavitation (the formation of bubbles in a liquid) and engine noise including azimuth/bow thruster noise from tugboats as concerning. However, notably, the Recovery Plan is referencing vessel noise as a whole across all vessels and the entirety of Cook Inlet, not POA's specified activity in the specified geographic region (

i.e.,

a heavily utilized port), which is a small portion of overall tugboat use in Cook Inlet throughout the year.

As described in the proposed rule (89 FR 85686, October 28, 2024) and this final rule, the POA is an industrialized area that regularly sees traffic from vessels ranging in size from a few meters to large cargo ships that dock and move cargo at the POA. Tugboats are required to assist in docking larger vessels and moving barges and construction equipment in the vicinity. As such, vessel noise is and has been part of the soundscape in Knik Arm at least since the opening of the POA facility on the same site in 1961 while the decline in the CIBW stock did not begin until the 1990s (NMFS 2016). The sound source levels of vessel activities range widely according to the type of vessel, and level of operational effort, with full power output and higher speeds generating more propeller cavitation and hence greater sound source levels than lower power output and lower speeds. Vessel movement around the POA is typically slow due to the needs of port operations, high vessel traffic, and a narrow navigational channel. The vessels required to support pile driving and extraction activities during the CTR project would be similar in type to those already operating at the POA during previous construction projects (

i.e.,

Petroleum and Cement Terminals (PCT), South Floating Dock (SFD), and NES1), and would not add significantly to the average sound levels from previous summer seasons during which CIBW continued to frequent Knik Arm and the general vicinity of the port (61N Environmental, 2021, 2022a, 2022b, 2025). It is important to note that there are multiple contextual factors (including the signal characteristics (

i.e.,

impulsivity, intensity, frequency, and duration) and the spatio-temporal (

i.e.,

space and time) acoustic footprint of POA's activity as well as bearing and distance, predictability of source movement, and likelihood of habituation to routine vessel traffic) that minimize the likelihood of behavioral disturbance even if a marine mammal is exposed to elevated sound levels relative to background sound levels. CIBWs regularly approach and pass the POA during normal port operations and during previous construction and dredging operations. While they are exposed to sounds from vessel traffic, the POA represents a small and relatively low-quality portion of the habitat, and the typical behaviors seen in the area are traveling and milling (61N Environmental 2020, 2021a, 2021b, 2025; Easley-Appleyard and Leonard 2022). No measurable increase in vessel traffic is expected at the POA as a result of the CTR project (POA 2024). Take by Level B harassment as a result of vessel noise is not considered reasonably likely to occur based on the long-term industrial nature of the area and the similarity of the expected vessel noise sources (

i.e.,

tugboats, barges, and small support vessels) to the existing vessel noise (

i.e.,

tugboats, barges, support vessels, and container ships) at the POA.

Additionally, the NMFS Alaska Regional Office's (AKRO) Biological Opinion under section 7 of the Endangered Species Act (ESA), which addressed the impacts of the CIBW take NMFS is authorizing in the context of both the environmental baseline and the cumulative effects (including vessel noise), found that it is not likely to jeopardize the continued existence of CIBWs or to destroy or adversely modify their designated Critical Habitat.

CBD states that NMFS failed to analyze potential take by Level B harassment from soft starts, a required mitigation measure during impact pile installation. Soft starts are required, among other reasons, to minimize the chances of injurious Level A harassment during exposure to impulsive sounds by first introducing lower-level sounds to the environment, allowing animals to move away from the sound source before the hammer energy increases to full power. In the case of CIBW, the shutdown zone established at the threshold for Level B harassment exceeds the predicted Level A harassment zone in all cases, and pile driving work (including soft starts) would be delayed upon observation of a CIBW approaching or within the shutdown zone. Thus, no Level B harassment of CIBW is expected from soft starts. For other marine mammal species, the predicted Level A harassment zone from impact driving of 72-in piles exceeds the Level B harassment and established shutdown

zone thresholds. Exposure during a soft-start procedure would occur within the predicted Level A harassment zone, and observations of animals within the Level A harassment zone during a soft-start and or subsequent impact driving would be recorded as a potential take by Level A harassment.

Comment 6:

Friends of Animals states that the proposed rule underestimates the effects of noise from the CTR project because NMFS did not consider the unlikely scenario of a third “spread” (

i.e.,

construction crew and associated equipment) of construction equipment working simultaneously at the POA during the CTR project.

Response:

As stated in the POA's application and the proposed rule, POA plans to operate no more than two vibratory hammers simultaneously. POA does not anticipate concurrent driving using three spreads for several reasons. First, the construction sequencing for pile installation and extraction involves long periods of equipment positioning, pile placement, bubble curtain placement (when required), and short periods of active pile driving. Pile sequencing requires that temporary piles are installed as a template, then larger permanent piles are installed, and then the temporary piles are removed. This required sequence plays out many times in this order during the construction season.

Comment 7:

CBD and Friends of Animals assert that NMFS' negligible impact determination is improper and arbitrary because it fails to account for “harassment by noise,” including vessel noise, in-water pile cutting, onshore demolition, and other construction activities that generate noise and that NMFS has no rational basis for concluding that the take proposed for authorization has no greater than a negligible impact on the species. CBD also asserts that NMFS's negligible impact determination is improper because it fails to consider cumulative impacts from other phases of the PAMP.

Response:

As described in the Description of Specified Activities section of the proposed rule (89 FR 85686, October 28, 2024), NMFS does not expect take of marine mammals from these activities because of the industrialized soundscape of the Port. CBD has not provided additional information for NMFS to consider to support its claim that take will occur from these activities. Furthermore, in the Negligible Impact Analysis and Determination section of the proposed rule and this final rule, we describe how the take estimated and authorized for POA's construction activity will have a negligible impact on all of the affected species or stocks, including CIBWs. We discuss how this determination is based upon, among other things, the number of takes of each stock that might be exposed to increased noise in each year and over the course of the 5-year ITR, the comparatively low intensity of behavioral harassment that might result from an instance of take that could occur within that year, and the likelihood that the mitigation measures required further lessen the likelihood, magnitude, or severity of exposures.

NMFS' negligible impact finding considers a number of parameters including, for example, the nature of the activities (

e.g.,

duration, sound source), effects/intensity of the taking, the context of takes, and mitigation. For CIBWs, NMFS considered data from previous similar construction activities, including previous phases of the PAMP. POA's previous monitoring efforts have yielded data showing that CIBWs continue to transit past the POA in construction seasons, and that behavioral responses to noise include reduced vocalizations, faster swim speeds, and increased group cohesion (61N Environmental 2020, 2021a, 2021b, 2025; Easley-Appleyard and Leonard 2022). Any disturbance that may occur is anticipated to be limited to behavioral changes such as increased swim speeds, changes in diving and surfacing behaviors, and alterations to communication signals, not the loss of foraging capabilities or the abandonment of critical habitat. Given these anticipated impacts, none of which would be expected to impact the fitness or reproduction of any individual marine mammals, much less adversely impact annual rates of recruitment or survival of CIBWs, NMFS' independent evaluation of the best scientific evidence in this case supports our negligible impact determination.

Neither the MMPA nor NMFS' implementing regulations require consideration of the take resulting from other activities in the negligible impact analysis. The preamble for NMFS' implementing regulations (54 FR 40338, September 29, 1989) states, in response to comments, that the impacts from other past and ongoing anthropogenic activities are to be incorporated into the negligible impact analysis via their impacts on the baseline. Consistent with that direction, NMFS has factored into its negligible impact analysis the impacts of other past and ongoing anthropogenic activities via their impacts on the baseline. The preamble of NMFS' implementing regulations also addresses cumulative effects from future, unrelated activities. Such effects are not considered in making the negligible impact determination under section 101(a)(5) of the MMPA. NMFS considers: (1) cumulative effects that are reasonably foreseeable when preparing a National Environmental Policy Act (NEPA) analysis; and (2) reasonably foreseeable cumulative effects under section 7 of the ESA for ESA-listed species, as appropriate. Accordingly, our analysis under NEPA in the final EA and consultation under Section 7 of the ESA does consider the cumulative impacts from nearby activities, including past and future phases of the PAMP. Further, the ESA Biological Opinion concluded that the CTR project is not likely to jeopardize the continued existence of CIBWs or to destroy or adversely modify designated CIBW critical habitat.

Comment 8:

CBD asserts that NMFS's negligible impact determination for all species relies on mitigation measures that depend upon the efficacy of visual monitoring measures that it claims are unreliable in Cook Inlet. CBD states that NMFS failed to acknowledge the difficulty of visually observing marine mammals via traditional aerial and boat-based surveys in year-round conditions.

Response:

NMFS disagrees that the mitigation and monitoring measures are ineffective, and CBD provides no additional information to support its claim. CBD's comment focuses on Cook Inlet as a whole as opposed to Knik Arm where the POA has a demonstrated history of successfully implementing a rigorous monitoring program during recent construction projects (

i.e.,

PCT, SFD, and NES1). Monitoring data from these projects provides evidence that their PSOs are capable of observing CIBWs out to 11,138-m from the CTR project site under good conditions, which is greater than any of the shutdown zones included in this rulemaking. Additionally, POA must delay pile installation if PSOs cannot effectively monitor the CIBW shutdown zone (

i.e.,

the largest shutdown zone) due to environmental conditions.

The proposed rule (89 FR 85686, October 28, 2024) and this final rule incorporate mitigation measures that are similar or identical to the measures required during the previous successful monitoring efforts. Additionally, the regulations require pile driving efforts to pause after completion of the current pile segment if weather or other conditions prevent PSOs from effectively observing the entire shutdown zone. These regulations require a minimum of four PSO stations and that at each station, at least two PSOs must be on watch at any given time. Further, the PSO stations must be

located so that the PSOs can fully monitor the shutdown zones and call for activities to be delayed when CIBWs are entering or observed within the Level B harassment zones. Observers will be positioned on stable land-based platforms, with suitable equipment, and will not be attempting to detect CIBWs in weather conditions deemed hazardous or which obscure the shutdown zones. Ice floes may occasionally be observed at the beginning and end of the construction season but are unlikely to significantly interfere with visual observations because construction work is impeded by ice and would not occur in conditions with high levels of ice.

NMFS has considered realistic assumptions of PSO effectiveness based on the precise configuration of the POA's visual monitoring program, as demonstrated during the PCT, SFD, and NES1 projects (61N Environmental, 2020, 2021a, 2021b, 2025). As part of the estimated take calculations for CIBW, NMFS first calculated the estimated take in the absence of mitigation measures and then applied a correction factor based on the most conservative estimate of potentially realized takes (68 percent) (61N Environmental 2025) from previous monitoring reports. The effectiveness of PSOs has thus been included in our analysis in both the proposed and final rules. This correction factor was not applied to other species authorized for take.

NMFS's Negligible Impact Determination relies on required mitigation measures being implemented by PSOs in order to limit the amount of noise to which CIBW may be exposed. Given the sizes of injurious (

i.e.,

Level A harassment) and behavioral (

i.e.,

Level B harassment) harassment zones in relation to the demonstrated visual range of PSOs, NMFS remains confident that the POA will effectively reduce the potential for exposure to noise sufficient to cause Level A harassment to zero. While PSOs may not spot some whales before they enter the Level B harassment zone, the intensity of take by Level B harassment is expected to be low, consisting of, at worst, temporary modifications in behavior while the whales transit through the area around POA on their way to foraging grounds in upper Knik Arm or out into greater Cook Inlet. Therefore, NMFS does not anticipate adverse effects on annual rates of recruitment or survival (

i.e.,

population-level effects).

Comment 9:

CBD and Friends of Animals assert that NMFS should defer authorization of incidental take of CIBWs unless and until NMFS has a better understanding of the reasons the species is failing to recover. They state that until it does so, NMFS has no rational basis for concluding that any number of take constitutes a “negligible impact” to the species.

Response:

NMFS shares the commenters' concern regarding the impacts of human activities on CIBWs and is committed to supporting the conservation and recovery of the species in accordance with its statutory responsibilities. However, section 101(a)(5)(A) of the MMPA requires upon request by U.S. citizens for NMFS, as delegated by the Secretary of Commerce, to allow the incidental taking of small numbers of marine mammals if it makes the necessary findings, which includes negligible impact. NMFS has defined negligible impact as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival (50 CFR 216.103).

Based on the best scientific evidence available, NMFS determined that the take, which is by Level B harassment only, incidental to POA's pile installation and removal activities, which is transient and of a generally low intensity, would have a negligible impact on CIBWs. No mortality, serious injury, or Level A harassment incidental to pile installation and removal activities is anticipated or authorized on CIBWs; therefore, no population effects are anticipated. Moreover, POA proposed and NMFS has required in these regulations a rigorous suite of mitigation measures to affect the least practicable adverse impact to CIBWs and other marine mammal species/stocks. The area within which CIBWs and other marine mammals could be exposed to elevated sound levels is limited to relatively low-quality, industrialized habitat primarily used as a travel corridor between foraging areas. No critical foraging grounds (

e.g.,

Eagle Bay, Eagle River, Susitna Delta) would be affected by sound from pile driving.

Results of recent studies provide evidence that the CIBW population increased between 2004 and 2010, declined after 2010, and increased again from 2016 to 2022 (Jacobsen

et al.,

2020; Shelden and Wade, 2019; Warlick

et al.,

2024; Goetz

et al.,

2023). While there is some uncertainty around CIBW population trend analyses, the results of these four studies are consistent in showing general trends. Thus, while Friends of Animals is correct that the status of CIBW abundance is less than certain, recent studies, which NMFS considers the best scientific information available, suggest the population may now be increasing (see Goetz

et al.,

2023). Additional data in the coming years will help to inform whether the recent positive trend in the CIBW population will continue. NMFS is taking several proactive steps to help protect and better understand the species. For more information, see NMFS' 5-year Priority Action Plan (2021-2025) for CIBWs as part of its Species in the Spotlight initiative (see

https://www.fisheries.noaa.gov/resource/document/species-spotlight-priority-actions-2021-2025-cook-inlet-beluga-whale

).

Furthermore, the ESA Biological Opinion determined that the issuance of the ITR is not likely to jeopardize the continued existence of CIBWs or to destroy or adversely modify CIBW critical habitat. The Biological Opinion also outlined Terms and Conditions and Reasonable and Prudent Measures to reduce impacts, which have been incorporated into the regulations.

Comment 10:

CBD commented that NMFS fails to ensure the least practicable adverse impact on CIBWs, the other species or stocks to be taken, and their habitats because NMFS failed to consider requiring several practicable mitigation measures. Friends of Animals recommended that NMFS should require more rigorous mitigation measures but did not provide any examples of such measures.

Response:

NMFS has included a suite of mitigation measures designed to effect the least practicable adverse impact on marine mammal species and their habitat and has also included appropriate monitoring and reporting requirements. Prior to starting pile driving activities, POA must conduct pre-clearance monitoring and may only commence activities once the shutdown zones have been monitored for 30 minutes and determined clear of marine mammals. At the start of pile driving, POA must use soft start techniques for impact pile driving (note that soft starts are considered ineffective for vibratory pile driving due to the non-impulsive nature of the sound source). During pile driving activities, POA must employ bubble curtains to reduce noise output in waters deeper than 3 m during all impact pile driving and during vibratory pile driving of permanent piles. If a marine mammal is observed within the shutdown zone, POA is required to halt activities until the animal has voluntarily left or has not been observed for species-specific time periods. Please see the Mitigation section of this final rule for a full description of the required mitigation measures.

Additional noise mitigation methods proposed by CBD included pile caps, dewatered cofferdams, and other physical barrier mitigation. NMFS does not consider pile caps an effective noise mitigation method because pile caps are used to protect piles and equipment during impact pile driving. They are typically made of wood or plastic and are designed to compress and fracture during use, limiting their consistency with respect to noise mitigation and potentially leading to safety issues if replaced during hammer operations (CALTRANS 2020). Additionally, because pile caps are used during most impact driving, any noise mitigation from caps is included in measured source values and proxy source values used in our analysis. Dewatered cofferdams are impracticable due to space restrictions in and around the POA, as well as the extreme environmental conditions in Knik Arm, including high tidal ranges and current velocities, as well as the unpredictable nature of ice movement during winter months. NMFS is not aware of other “physical barrier mitigation” methods that have been used during coastal construction projects, and CBD did not provide further examples.

CBD also stated that NMFS failed to consider the least practicable adverse impact to beluga whale habitat in Cook Inlet but neither provides any specific examples of adverse habitat impacts nor suggested mitigation measures. NMFS acknowledges that a minimal amount of low-quality habitat will be lost due to the expansion of the terminal footprint and that water-column noise levels will be increased during construction. While most of the physical and biological features essential to the CIBW critical habitat are found at the POA, and CIBW Biologically Important Area (BIA) includes the waters around the POA, this area represents a very small portion of the overall habitat available and is not known to be an important foraging or resting site for this stock (61N Environmental 2020, 2021a, 2021b, 2025). We anticipate minimal impacts to prey or other habitat features as outlined in the proposed rule (89 FR 85686; October 28, 2024) and this final rule.

Comment 11:

CBD commented that NMFS fails to ensure the least practicable adverse impact on CIBWs, the other species or stocks to be taken, and their habitats because NMFS failed to consider requiring the use of passive acoustic monitors (PAM) as a way to evaluate at the end of the construction activities (seasonal or comprehensive) whether CIBWs or other marine mammals went undetected by PSOs during visual monitoring.

Response:

NMFS agrees that archival PAM data would be useful in evaluating the presence of CIBWs at the POA and the effectiveness of the PSOs during times of visual observations. While some CIBWs and other marine mammals may not be detected by PSOs before entering the shutdown zones (61N Environmental, 2020, 2021a, 2021b, 2025), the design and deployment of the PAM systems and data analysis is too time- and cost-intensive to be practicable to the POA. An article on NOAA's website illustrates the level of customization, expertise, and difficulty required to assemble a passive acoustic mooring suitable for deployment in Cook Inlet (see

https://www.fisheries.noaa.gov/science-blog/beluga-whale-acoustic-monitoring-survey-post-3

).

Background acoustic conditions, including flow noise from strong currents, large tidal changes, weather, and normal port operations, along with additional noise from the project (

e.g.,

pile driving) can make it difficult to detect marine mammals during PAM, particularly when the site is known to be noisy (as it is at POA). Further, the data stored on these types of moorings is not accessible until they are retrieved by the researcher who deployed them. Lessons learned from prior sound source verification studies carried out at the POA (

e.g.,

I&R, 2021a, 2022b) indicate that Knik Arm is a very challenging environment in which to collect high quality acoustic data usable by NMFS, the POA, and others due to the presence of strong tidal currents, which can create substantial flow noise in recordings, and prevalent anthropogenic noise, which can mask acoustic signals of interest. Specifically, during the CTR project, multiple barges, tugboats, and other support vessels, which can obscure signals of interest, will be within the CTR project area at all times during the CTR project. As mentioned in the proposed rule (89 FR 85686, October 28, 2024) with respect to near-real-time PAM devices, the constraints of the system design even for archival moored systems and the known challenges of the area make PAM impracticable for the POA.

Comment 12:

CBD commented that NMFS fails to ensure the least practicable adverse impact on CIBWs, the other species or stocks to be taken, and their habitats because NMFS failed to consider requiring seasonal restrictions.

Response:

Contrary to CBD's assertion, NMFS did consider a seasonal restriction for this project, in addition to the PSO requirements. We note that August through October are months with high CIBW abundance, and NMFS expects that the POA will likely have to shut down pile driving activities more frequently during that time period due to the increased presence of CIBWs in Knik Arm. The POA is planning to complete in-water work as early in the construction season as is practicable. However, due to the scope of the CTR project and the needs of the construction sequencing, it is not practicable to restrict pile driving to any specific time periods or areas (

e.g.,

only allowing pile driving April through July or restricting vibratory driving but not impact driving to such periods). The necessary pile sequencing requires that temporary piles are installed as a template, then larger permanent piles are installed, and then the temporary piles are removed. This required sequence plays out many times, in this order, during the open water construction season. It is therefore not possible for POA to install all of the larger permanent piles during the early season and install temporary piles later in the season; the larger and smaller piles must be alternated.

Furthermore, there are potential consequences of pausing or delaying the construction season, including de-rating the structural capacity of the existing docks, a shutdown of dock operations due to deteriorated conditions, or an actual collapse of one or more dock structures. The potential for collapse increases with schedule delays, due to both worsening deterioration and the higher probability of a significant seismic event occurring. Any of these scenarios could have dire consequences for the populations of Anchorage and Alaska who are served by the POA. In this context, NMFS has determined that the current mitigation and monitoring measures affect the least practicable adverse impact on marine mammal species and stocks.

Comment 13:

CBD commented that NMFS fails to ensure the least practicable adverse impact on CIBWs, the other species or stocks to be taken, and their habitats because NMFS failed to consider requiring the use of drones to help detect the presence of marine mammals.

Response:

While unmanned aerial vehicles (UAVs) (

i.e.,

drones) have been used in some instances to observe marine mammals, there are logistical reasons why this measure is not practicable for POA to implement for this project. The POA is uniquely situated adjacent to an active military installation and airfield (Joint Base Elmendorf-Richardson (JBER)) and in close proximity to several civilian airports, including Ted Stevens Anchorage International Airport, Merrill

Field Airport, and Lake Hood Seaplane Base (the world's largest and busiest seaplane base). As such, the surrounding airspace is complex and heavily trafficked with general aviation, commercial (including cargo), and military aircrafts.

Flying UAVs at the POA or over Knik Arm would require FAA approval for four different jurisdictions of airspace in the Anchorage Terminal Area (14 CFR part 93 Subpart D). In order to obtain permission for drones, an event specific Notice to Airmen must be approved by the FAA and JBER. The JBER tower requires 48-hour notice prior to launch and 100 percent phone communication during all drone activities. In addition, the drone operator would have to be in constant communication with each respective airspace the drone occupies as it transits between segments over Knik Arm. Previous efforts to conduct surveys using UAV have shown that this is not practicable.

The POA operates a robust marine mammal monitoring program that utilizes multiple stations, big-eye binoculars, theodolites, and cloud-based mapping among four observation stations spaced along a linear distance of about 8.5 kilometers of coastline. It is unlikely drones would provide additional benefit to the monitoring program. The least practical adverse impact to CIBW and other marine mammals is thus achieved through standard PSO requirements already included in the proposed rule, and therefore, NMFS has not required that POA use UAVs to assist in detecting marine mammals during their planned construction activities.

Comment 14:

CBD commented that NMFS fails to ensure the least practicable adverse impact on CIBWs, the other species or stocks to be taken, and their habitats because NMFS failed to consider requiring the use of bubble curtains in all months and water depths. They stated that NMFS should require the POA to employ confined bubble curtains during all pile driving activities in all months and that no justification was given for not requiring the use of a bubble curtain in waters less than 3 m deep. CVTC stated that bubble curtains should be required for all impact or vibratory driving of any pile type (permanent or temporary) of all pile sizes (24-, 36-, and 72-in as well as other sizes) in all water depths (0.1 m and deeper) in all months of the year, and that between August and October two separate and completely overlapping layers of bubble curtains should be required, or that alternatively impact and vibratory driving of any pile type should be prohibited during those months.

Response:

NMFS considered the practicability of requiring the POA to use a bubble curtain in all construction months in conjunction with the need for POA to complete most work during the beginning of construction seasons (

i.e.,

in the months of April-July) when CIBWs are less likely to be present at the POA. In the proposed rule (89 FR 85686, October 28, 2024), we acknowledged the use of bubble curtains on all piles has the potential to drive the in-water construction schedule further into the late summer months, which are known for higher CIBW abundance in the CTR project area, thus lengthening the duration of potential interactions between CIBW and in-water work. Given the data from the 2024 NES1 construction project showing increased prevalence of CIBW near the POA and the resulting delays in construction due to work shutdowns (see Comment 2 and Response, above), NMFS determined that use of a bubble curtain for all piles in all months may ultimately result in increased impacts to CIBW by lengthening the total duration of the CTR project over additional years. This final rule maintains the requirement for POA to utilize a bubble curtain during all impact and vibratory driving of permanent 72-in piles in waters deeper than 3 m in all months, reducing the likelihood of auditory injury to all marine mammal species, particularly those for which the Level A harassment isopleth may exceed the shutdown zone. The least practicable adverse impact to CIBW and other marine mammals is thus achieved without requiring the use of bubble curtains during vibratory pile driving. Bubble curtains may be used at the POA and contractor's discretion.

With respect to the depth constraint specified in the proposed ITR, designing a bubble curtain that can handle the rapid rise and fall of the tides is infeasible. The average tidal range in Knik Arm is about 8 m (26 ft) and can be as great as 10.7 m (35 ft) (Lipscomb 1989). This means that when the tide level changes from low to high or from high to low, which takes about 5 hours and 15 minutes, the rate of change can be 1.5 to 2 vertical m (5 to 6.7 ft) per hour. Such a rapid increase and decrease in tide level makes it impossible to increase or decrease the number of rings and keep a bubble curtain system operating under water with full air flow and pressure. If an air hole is above water, it will create an easier route for air release and compromise the air pressure in the entire system. The POA encourages the contractor to install and remove piles at low tide or in the dry, when possible, which greatly reduces sound pressure levels in water. The 3 m cutoff for use of a bubble curtain gives contractors some flexibility to complete a pile installation under rapidly changing conditions.

Similarly, the design of the bubble curtain required for impact and vibratory driving of permanent piles is at the discretion of the contractor for the CTR project. While POA used a confined bubble curtain during the first year of the PCT project, there were significant financial expenses associated with the design and time delays required for operations that were reduced with the use of an unconfined system during the second year of the PCT project. Confined and unconfined bubble curtain systems required an average of 6 and 4 hours, respectively, for deployment and retrieval operations. Utilization of a double bubble curtain, as recommended by CVTC, would increase the costs and delays associated with single curtains. Additionally, requirements for more equipment increase safety concerns associated with deck space on work barges and maneuvering space in and around the POA and the construction site. Therefore, it is impracticable for the POA to implement these suggested mitigation measures except at the discretion of the contractor.

Comment 15:

CBD states that NMFS should prepare programmatic NEPA and ESA analyses for its CIBW take authorizations. CBD states that at a minimum, NMFS should analyze the PAMP in a single NEPA and ESA review that considers all cumulative, indirect, and direct environmental effects.

Response:

NMFS originally declared its intent to prepare an EIS for take authorizations in Cook Inlet, Alaska (79 FR 61616, October 14, 2014). However, in a 2017

Federal Register

notification (82 FR 41939, September 5, 2017), NMFS indicated that in part due to a reduced number of incidental take authorization requests in the region, we were postponing any potential preparation of an EIS for take authorizations in Cook Inlet. As stated in the 2017

Federal Register

notice, NMFS should the number of ITA requests, or anticipated requests, noticeably increase, NMFS will re-evaluate whether preparation of an EIS is necessary. Currently, the number of ITA requests for activities that may affect marine mammals in Cook Inlet is at such a level that preparation of an EIS is not appropriate. Nonetheless, under NEPA, NMFS is required to consider cumulative effects of other potential

activities in the same geographic area, and these are discussed in greater detail in the Final EA prepared for this promulgation of an ITR to the POA for the CTR project, which supports our finding that NMFS' issuance of the POA ITR will not have a significant impact on the human environment.

CBD asserts that NMFS should analyze the PAMP in a single NEPA review, rather than “segmenting” the various PAMP phases. NMFS has appropriately analyzed and captured all past, present and reasonably foreseeable future actions under NEPA. This includes the projects associated with the PAMP, which each have independent utility and require separate authorizations and NEPA analyses. The EAs for each PAMP activity appropriately analyze the cumulative, indirect, and direct environmental effects of each specified action. They include an evaluation of each action's affected area, the scale and geographic extent of each action, and the degree of cumulative effects on resources (

e.g.,

the duration of impact, and whether the impacts were adverse and/or beneficial and their magnitude) under NEPA.

NMFS can prepare an EA so long as the record supports the conclusion that potential impacts are not “significant” for the purposes of NEPA. Based on the information presented in the application and NMFS' Policy and Procedures for Compliance with the NEPA and Related Authorities (Companion Manual (CM) for NOAA Administrative Order (NAO) 216-6A) (NOAA 2017), sections 3 and 7, NMFS' determination to prepare an EA is appropriate and in compliance with NEPA, NMFS appropriately signed a Finding of No Significant Impact (FONSI) for the promulgation of the ITR for incidental take associated with the POA's CTR project in support of this determination. The FONSI concluded that NMFS' proposed action, the promulgation of an ITR and issuance of an associated LOA to the POA, will not meaningfully contribute to significant impacts to specific resources, given the limited scope of NMFS' action and required mitigation measures. Accordingly, preparation of an EIS for this action is not necessary.

With respect to ESA, while a programmatic approach streamlines the procedures and time involved in consultations for broad agency programs or multiple similar, frequently occurring, or routine actions with predictable effects on listed species and/or critical habitat, it is discretionary. This approach depends on knowing with reasonable certainty the broad types of actions and the expected impacts to the species. In Cook Inlet, NMFS consults on a wide variety of activities, including coastal construction, oil and gas exploration and extraction, research, and military readiness efforts. The variety of actions and potential impacts is such that NMFS is unable to conduct a programmatic Section 7 consultation for all actions that may impact CIBW. While a programmatic consultation for similar types of actions (

i.e.,

coastal construction) could be considered, NMFS still lacks relevant details such as project duration and design specifics for projects like the PAMP, which are funded and designed in phases. The timeline for the CTR project's funding and design, in combination with the vulnerability of this critical infrastructure to seismic events, makes a programmatic consultation impractical.

While a programmatic approach is currently not possible, the ESA requires consideration of cumulative impacts during the preparation of the Biological Opinion (BiOp). The NMFS Alaska Regional Office issued a BiOp concluding that the take, by harassment, of CIBW, humpback whales (Mexico-North Pacific DPS and Western North Pacific DPS), and Steller sea lions (Western DPS) would not jeopardize the continued existence of those stocks and the takings would not adversely modify critical habitat. The full analysis supporting these conclusions can be found in the BiOp (NMFS, 2025).

Comment 16:

CBD and Friends of Animals believe the draft EA for the CTR project fails to comply with the requirements of NEPA. They stipulate that the draft EA fails to consider a reasonable range of alternatives and to consider impacts of vessel noise associated with the CTR project and lacks a meaningful environmental and cumulative impacts analysis. Friends of Animals recommended that NMFS should conduct a more comprehensive assessment of the cumulative effects related to noise, habitat degradation, chemical exposure, mortality, stranding, climate change, and migration of the species and its prey, specifically mentioning potential synergistic effects of noise and toxic chemical exposure.

Response:

In accordance with the NEPA, NMFS is required to consider a reasonable range of alternatives to a Proposed Action, as well as a No Action Alternative. Reasonable alternatives are viable options for meeting the purpose and need for the proposed action. The evaluation of alternatives under NEPA assists NMFS with understanding, and as appropriate, minimizing impacts through an assessment of alternative ways to achieve the purpose and need for our Proposed Action. Reasonable alternatives are carried forward for detailed evaluation under NEPA while alternatives considered but determined not to meet the purpose and need are not carried forward. For the purposes of this EA, an alternative will only meet the purpose and need if it satisfies the requirements of section 101(a)(5)(A) of the MMPA.

In accordance with NOAA's implementing procedures, the CM for NAO 216-6A, Section 6.B.i, NMFS is defining the No Action alternative as not authorizing the requested incidental take of marine mammals under Section 101(a)(5)(A) of the MMPA. This is consistent with our statutory obligation under the MMPA to either: (1) deny the requested authorization; or (2) grant the requested authorization and prescribe mitigation, monitoring, and reporting requirements. The Preferred Alternative (

i.e.,

promulgation of the ITR) includes mandatory mitigation, monitoring, and reporting requirements for POA to achieve the MMPA standard of effecting the least practicable adverse impact on each species or stock of marine mammal and their habitat, paying particular attention to rookeries, mating grounds, and other areas of similar significance. Since NMFS is required to prescribe mitigation to effect the least practicable adverse impact on marine mammals, mitigation that reduces impacts on marine mammals is inherently included in Alternative 2 (the proposed action) and is included as part of the analysis of alternative(s) in the Environmental Consequences chapter in the EA. NMFS described both the No Action Alternative and Preferred Alternative in the EA. We have also included an “Alternatives Considered but Eliminated from Further Consideration” section in the final EA that considered whether other alternatives could meet the purpose and need while supporting this applicant's proposal to replace the existing cargo terminals at the POA. There is no requirement under NEPA to consider more than two alternatives or to consider alternatives that are substantially similar to other alternatives or which have substantially similar consequences. NMFS' range of alternatives is based on the proposed action and the purpose and need, which are linked to NMFS' authorities under the MMPA. For the purposes of analysis under NEPA in the EA, an alternative will only meet the purpose and need if it satisfies the requirements under section 101(a)(5)(A) of the MMPA. Therefore, NMFS determined that, based on our authorities and criteria under the MMPA, which included

criteria regarding mitigation measures, appropriate considerations were applied to identify which alternatives to carry forward for analysis.

NMFS considered vessel noise as a component of the acoustic environment in Cook Inlet and near the POA in section 3.2.3.3 of the Draft EA. We have revised the final EA to more explicitly discuss the potential impacts of vessel noise; however, these additions do not change the conclusions reached in the Draft EA.

CBD asserts that NMFS “fails to disclose or analyze the unique threat that the cumulative effects of multiple stressors have on” CIBWs. NMFS evaluated the cumulative impacts of multiple stressors associated with the past, present, and reasonably foreseeable future actions in the action area, including projects associated with other PAMP phases, vessel noise (

e.g.,

commercial shipping traffic and vessel noise associated with the CTR project), vessel traffic in Knik Arm, and research activities in Section 4.8 of the EA. Vessel operations at the POA are not expected to measurably increase as a result of the CTR project (POA 2024). As stated in the EA, while consideration of activities in sum suggests an increase in industrialization of Cook Inlet, many of the past, present, and reasonably foreseeable future actions are spatially and temporally limited and do not permanently reduce or degrade the habitat available to marine mammals or their prey species. While the CTR project would add an incremental contribution to the combined environmental impacts of other past, present, and reasonably foreseeable future actions; those direct and indirect adverse impacts are expected to be mainly short-term, localized, and minor, as described in the EA. None of the take authorized by NMFS in other ITAs would overlap in time or space with impacts from the CTR project.

NMFS appreciates Friends of Animals' recommendation for conducting a more comprehensive study of cumulative effects of the various stressors on CIBW. While Friends of Animals does not provide any new information on cumulative effects, including synergistic effects of marine pollution and noise, this has been studied in other beluga populations. Williams

et al.

(2021) found that in St. Lawrence River belugas, the combined effects of proximate threats such as ocean noise, prey limitation, and contaminants were less significant that the potential threats from global climate change and the resulting expected changes to habitat. Of note, while the Recovery Plan for the Cook Inlet Beluga Whale cited by Friends of Animals identifies pollution as a threat, it notes that available information indicates that the magnitude of the pollution threat to CIBW appears low, though not all pollutants to which CIBW are exposed have been studied in that environment. NMFS has revised the EA to include more information on the potential for exposure to contaminants to harm the health of CIBW.

Comment 17:

CTVC states that the POA should cover the costs of having NMFS study the noise protections offered by the bubble curtains including during different water temperatures, sediment loads, water currents, and other factors which may affect the protections for whales and that NOAA NMFS and the Port of Alaska should meet annually to discuss methods and devices for protection of whales that can be implemented in subsequent months/years of the CTR project.

Response:

Per section 101(a)(5)(A) of the MMPA, NMFS can require holders of issued authorizations to conduct monitoring for marine mammals during the specified activities, but it cannot require an applicant to fund specific NMFS studies. The POA has previously completed hydroacoustic monitoring of pile driving activities during the PCT project, including the effectiveness of bubble curtains, as part of required monitoring. In the proposed ITR, NMFS considered the mitigatory value of additional hydroacoustic monitoring and determined that more data would not significantly add to the value of the current dataset. If POA elects to conduct hydroacoustic monitoring, NMFS will include those data in future analyses.

Adaptive management is a key part of the ITR process (see § 217.18 Modifications of Letters of Authorization of the new regulatory text provided by this final rule). The POA submits monitoring reports to NMFS recording marine mammal sightings during each year of the CTR project. For the CTR project, weekly reports are required. NMFS tracks these reports and estimates take numbers for each species during the construction season. NMFS may modify LOA mitigation, monitoring, or reporting measures if doing so creates a reasonable likelihood of more effectively accomplishing the goal of the measure. Additionally, any new technologies or methods for reducing impact on marine mammals can be cause to update the required mitigations set forth in these regulations.

Changes From the Proposed Rule

There have been several changes from the proposed rule in this final rule. First, NMFS finalized the draft 2024 Updated Technical Guidance referenced in the proposed rule on October 24, 2024 (89 FR 84872). The incorporation of this updated guidance did not change the estimated take of marine mammals or the shutdown zones because the proposed rule analyzed the draft Updated Technical Guidance in anticipation of its incorporation in the final rule. Consistent with the Updated Technical Guidance, nomenclature changes have been made to the final rule: mid-frequency cetaceans have been re-classified as high-frequency cetaceans, and high-frequency cetaceans have been updated to very-high-frequency (VHF) cetaceans.

Secondly, NMFS has incorporated the most recent sighting data (from 2024) into our analysis of the sighting rate bins, and thus, the estimated take (see tables 13 and 17 in this notice). Take estimates for all years increased due as a result of inclusion of these updated data in the analysis. Additionally, NMFS has concurred with the change requested by the POA in their public comment letter (see

Comment 2

and

Response,

above) and removed the proposed requirement for the use of bubble curtains during vibratory driving of temporary (24-in or 36-in) piles, which was proposed to be implemented during the months of August through October. The removal of the bubble curtain requirement does not affect estimated take because attenuated and unattenuated vibratory pile driving isopleths both occurred in the same sighting rate bin in the estimated take analysis (see Estimated Take for more information).

Thirdly, NMFS has added the Western North Pacific (WNP) stock of humpback whale (

Megaptera novaengliae

) to this rule (see table 1). The POA did not request, and thus NMFS did not propose, take of the WNP stock of humpback whales because few individuals from this stock are estimated to occur in Cook Inlet (NMFS, 2025). However, as a result of NMFS' section 7 consultation under the ESA, impacts to the WNP stock were analyzed jointly with the impacts to the Mexico-North Pacific stock. Estimated take for this species has not changed because take was not delegated to stock level because it is not possible to identify humpback whales by stock in the field. In Cook Inlet, humpback populations are approximately 89 percent Hawaii DPS individuals, 11 percent Mexico DPS individuals, and less than one percent WNP DPS individuals (NMFS 2025).

Finally, the regulatory text in the proposed rule omitted language related

to qualifications of PSOs, which was included in the text of the rule and a requirement that PSO data be submitted in a queryable format, which was not. The regulatory language and text of the rule have been revised accordingly.

There are also several typographical errors in the Proposed Rule that are corrected in this notice. First, in the Summary of Major Provisions Within the Proposed Rule section, the proposed rule stated that shutdown zones for non-CIBW species would be equivalent to or greater than the estimated Level A harassment zones. This should have read “Establishment of shutdown zones equivalent to or greater than the estimated Level A harassment zones during vibratory pile driving; and at a practicable distance during impact driving for other species.” The shutdown zones for non-CIBW species during impact driving do not exceed the Level A harassment isopleths, as PSOs are unlikely to see some species at such distances. This was accurately described in the Mitigation section of the proposed rule.

Second, two errors were present in the “Number of Days over 5 Years” column in table 1 of the proposed rule. The number of days of temporary pile installation should be 159 instead of 144, and the number of days of temporary pile removal should be 19 instead of 15. The correct number of days was used in the take estimation and thus these corrections do not affect the take estimates.

Third, discussion of ensonified area within the Estimated Take section of the proposed rule (89 FR 85686, October 28, 2024) stated that “for vibratory driving during the CTR Project, it is assumed that a well-designed and robust bubble curtain system will achieve a mean reduction of 7 dB at the source.” This statement should have specified that the assumption applied only to 72-in permanent piles during vibratory driving, and that measurements of attenuated installation and extraction of temporary (24-in and 36-in) piles were used in the analysis.

Fourth, tables 15 and 16 of the proposed rule had an incorrect Level B harassment distance for vibratory removal (attenuated) of a 24-in pile; the table read 2,583 m when the correct distance is 2,089 m. This is corrected in table 10 of this final rule.

Finally, due to a rounding error, the Level A take estimates for harbor seals and harbor porpoise in table 25 (99 and 16, respectively) of the proposed rule did not match the values shown in tables 21 and 22 (98 and 15, respectively). The values in tables 21 and 22 were correct. The total maximum annual take estimates have been adjusted in table 19 of this final rule.

Description of Marine Mammals in the Specified Geographical Region

There are seven species, comprising 10 stocks, of marine mammals that may be found in upper Cook Inlet during the proposed construction and demolition activities. Sections 3 and 4 of the POA's application and request for regulations summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history of the potentially affected species. NMFS fully considered all of this information, and we refer the reader to these descriptions, instead of reprinting the information. Additional information regarding population trends and threats may be found in NMFS' Stock Assessment Reports (SARs) (see

https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments

) and more general information about these species (

e.g.,

physical and behavioral descriptions) may be found on NMFS' website at:

https://www.fisheries.noaa.gov/find-species.

Table 1 lists all species or stocks for which take is likely and may be authorized for the specified activities and summarizes information related to the population or stock, including regulatory status under the MMPA and ESA and potential biological removal (PBR), where known. PBR is defined by the MMPA as “the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population” (16 U.S.C. 1362(20)). While no serious injury or mortality is anticipated or proposed to be authorized here, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species or stocks and other threats.

Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS' stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All managed stocks in this region are assessed in NMFS' U.S. Alaska and Pacific SARs (

e.g.,

Carretta,

et al.,

2023; Young

et al.,

2023, 2024). Values presented in table 1 are the most recent available at the time of publication, including from the draft 2024 SARs, and are available online at:

https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports.

Table 1—Species Likely Impacted by the Specified Activities

Common name

Scientific name

MMPA stock

ESA/

MMPA status;

strategic

(Y/N)

1

Stock abundance

N

best

, (CV, N

min

,

most recent

abundance survey)

2

PBR

Annual

M/SI

3

Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales)

Family Eschrichtiidae:

Gray whale

Eschrichtius robustus

Eastern N Pacific

-/-; N

26,960 (0.05, 25,849, 2016)

801

131

Family Balaenopteridae (rorquals):

Humpback whale

Megaptera novaeangliae

Hawaii

-, -, N

11,278 (0.56, 7,265, 2020)

127

27.09

Mexico-North Pacific

T, D, Y

N/A (N/A, N/A, 2006)

4

UND

0.57

Western North Pacific

5

E,D,Y

1,084 (0.088, 1,007, 2006)

3.4

5.82

Order Cetartiodactyla—Superfamily Odontoceti (toothed whales, dolphins, and porpoises)

Family Delphinidae:

Killer whale

Orcinus orca

Eastern North Pacific Alaska Resident

-/-; N

1,920 (N/A, 1,920, 2019)

19

1.3

Eastern North Pacific Gulf of Alaska, Aleutian Islands and Bering Sea Transient

-/-; N

587 (N/A, 587, 2012)

5.9

0.8

Family Monodontidae

Beluga whale

Delphinapterus leucas

Cook Inlet

E/D; Y

331 (0.076, 311, 2022)

0.62

0

Family Phocoenidae (porpoises):

Harbor porpoise

Phocoena phocoena

Gulf of Alaska

-/-; Y

31,046 (0.214, N/A, 1998)

4

UND

72

Order Carnivora—Superfamily Pinnipedia

Family Otariidae (eared seals and sea lions):

Steller sea lion

Eumetopias jubatus

Western

E/D; Y

49,837 (N/A, 49,837 2022)

299

267

Family Phocidae (earless seals):

Harbor seal

Phoca vitulina

Cook Inlet/Shelikof Strait

-/-; N

28,411 (N/A, 26,907, 2018)

807

107

1

Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.

2

NMFS marine mammal stock assessment reports online at:

https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).

3

These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (

e.g.,

commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range.

4

UND means undetermined.

5

PBR in U.S. waters = 0.2, M/SI in U.S. waters = 0.06.

A detailed description of marine mammals in the specified geographic region, including brief introductions to the species and relevant stocks (with the exception of the WNP stock of humpback whales), as well as available information regarding population trends and threats, and information regarding local occurrence, were provided in the proposed rule (89 FR 85686, October 28, 2024). Please refer to the proposed rule (89 FR 85686, October 28, 2024) for full descriptions of all species.

The WNP stock is fully aligned with the WNP DPS and the stock range includes humpback whales in the Mariana Archipelago, as they are known to be part of this DPS based on both photographic identification matches and genetics (Hill et al. 2020). It consists of two units: the Philippines/Okinawa—North Pacific unit and the Marianas/Ogasawara—North Pacific unit. The units are managed as a single stock at this time, due to a lack of data available to separately assess them (NMFS 2023a, NMFS 2019, NMFS 2022d). Recognition of these units is based on movements and genetic data (Oleson

et al.

2022). Whales in the Philippines/Okinawa—North Pacific unit winter near the Philippines and in the Ryukyu Archipelago and migrate to summer feeding areas primarily off the Russian mainland (Oleson

et al.

2022). Whales that winter off the Mariana Archipelago, Ogasawara, and other areas not yet identified and then migrate to summer feeding areas off the Commander Islands, and to the Bering Sea and Aleutian Islands comprise the Marianas/Ogasawara—North Pacific unit.

Since the publication of the proposed rule in October 2024, two marine mammal entanglement or stranding events have been documented. On October 1, 2024, PSOs working on the POA's North Extension Stabilization (NES) project spotted a CIBW entangled in an unknown object (possibly a tire inner-tube) near the POA (61N Environmental, 2025). The whale was sighted again on October 2 but was not seen after that time. Video footage of the individual was taken, and the whale was determined to be a subadult, at least 7 years old (NMFS, 2024). The entanglement was determined to be life-threatening, but the whale was not seen after October 2, and no disentanglement effort was possible. This is the third known entanglement of a free-swimming CIBW; the others were observed in 2005 and 2010. There is no evidence that the entanglement material originated at the POA or that the pile driving occurring at the time of the observation contributed in any way to the entanglement or subsequent behavior. The POA implements measures to ensure construction materials and waste products do not enter Cook Inlet. The impacts of this entanglement were limited to the entangled individual, and NMFS does not believe that this type of event is likely to recur as a result of the POA's planned activities.

In November 2024, a deceased juvenile fin whale (

Balaenoptera physalus

) stranded close to Anchorage. Fin whales are common in lower Cook Inlet but uncommon in the upper inlet and the carcass is likely to have been moved to the upper inlet by tidal currents. Therefore, while NMFS acknowledges that there is a possibility of a fin whale approaching Anchorage during the CTR project, we do not believe that take of this species is reasonably likely to occur in the specified geographic region. Fin whales were excluded from further analysis in the proposed rule, and NMFS finds that this new information does not influence its conclusions regarding fin whales.

Marine Mammal Hearing

Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Not all marine mammal species have equal hearing capabilities (

e.g.,

Richardson

et al.,

1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall

et al.

(2007, 2019) recommended that marine mammals be divided into hearing groups based on directly measured (behavioral or auditory evoked potential techniques) or estimated hearing ranges (behavioral response data, anatomical

modeling,

etc.

). Note that no direct measurements of hearing ability have been successfully completed for mysticetes (

i.e.,

low-frequency cetaceans). Subsequently, NMFS (2018, 2024) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 dB threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall

et al.

(2007) retained.

On May 3, 2024, NMFS published and solicited public comment on its draft Updated Technical Guidance (89 FR 36762), which includes updated hearing ranges and names for the marine mammal hearing groups. This guidance was finalized on October 24, 2024 (89 FR 84872) with no substantive changes. In the proposed rulemaking, we considered both the 2018 and 2024 Technical Guidance in our effects and estimated take analysis. Therefore, the estimated take analysis in the proposed rule based on the draft 2024 Technical Guidance incorporates the best available scientific information and is carried forward in this final rule. Table 2 shows the updated hearing groups included in the 2024 Updated Technical guidance.

Table 2—Marine Mammal Hearing Groups

[NMFS 2024]

Hearing group

Generalized

hearing range *

UNDERWATER:

Low-frequency (LF) cetaceans (baleen whales)

7 Hz to 36 kHz.

High-frequency (HF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales)

150 Hz to 160 kHz.

Very High-frequency (VHF) cetaceans (true porpoises,

Kogia,

river dolphins, Cephalorhynchid,

Lagenorhynchus cruciger

&

L. australis

)

200 Hz to 165 kHz.

Phocid pinnipeds (PW) (underwater) (true seals)

40 Hz to 90 kHz.

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals)

60 Hz to 68 kHz.

IN-AIR:

Phocid pinnipeds (PA) (true seals)

42 Hz to 52 kHz.

Otariid pinnipeds (OA) (sea lions and fur seals)

90 Hz to 40 kHz.

* Represents the generalized hearing range for the entire group as a composite (

i.e.,

all species within the group), where individual species' hearing ranges may not be as broad. Generalized hearing range chosen based on ~65 dB threshold from composite audiogram, previous analysis in NMFS 2018, and/or data from Southall

et al.

2007; Southall

et al.

2019. Additionally, animals are able to detect very loud sounds above and below that “generalized” hearing range.

For more detail concerning these groups and associated frequency ranges, please see NMFS (2024) for a review of available information.

Potential Effects of the Specified Activity on Marine Mammals and Their Habitat

The effects of underwater noise from the POA's construction activities have the potential to result in harassment of marine mammals in the vicinity of the CTR project area. The proposed rule (89 FR 85686, October 28, 2024) included a discussion of the effects of anthropogenic noise on marine mammals and the potential effects of underwater noise from pile installation and extraction activities on marine mammals and their habitat. There is no newly available relevant information that would change our analyses or the results thereof. Please refer to the proposed rule (89 FR 85686, October 28, 2024) for the potential effects of the POA's activities on marine mammals and their habitat.

Estimated Take of Marine Mammals

This section provides an estimate of the number of incidental takes that may be authorized through issuance of a LOA, which will inform NMFS' consideration of “small numbers,” the negligible impact determinations, and impacts on subsistence uses.

Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment” as any act of pursuit, torment, or annoyance, which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (

i.e.,

Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (

i.e.,

Level B harassment).

Authorized takes will primarily be by Level B harassment, as use of the acoustic sources (

i.e.,

vibratory and impact pile driving) has the potential to result in disruption of behavioral patterns for individual marine mammals. There is also some potential for auditory injury (AUD INJ) constituting Level A harassment to result, primarily for very high frequency (VHF) cetaceans and phocids because predicted AUD INJ zones are larger than for high-frequency cetaceans and otariids. AUD INJ is unlikely to occur for mysticetes, high-frequency cetaceans, and otariids due to measures described in the Mitigation section. The required mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable. As described previously, no serious injury or mortality is anticipated or authorized for this activity. Below, we describe how the authorized take numbers were estimated.

For acoustic impacts, generally speaking, we estimate take by considering: (1) acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (2) the area or volume of water that will be ensonified above these levels in a day; (3) the density or occurrence of marine mammals within these ensonified areas; and, (4) the number of days of activities. We note that while these factors can contribute to a basic calculation to provide an initial prediction of potential takes, additional information that can qualitatively inform take estimates is also sometimes available (

e.g.,

previous monitoring results or average group size). Below, we describe the factors considered here in more detail and present the authorized take estimates.

Acoustic Thresholds

NMFS recommends the use of acoustic thresholds that identify the

received level of underwater sound above which exposed marine mammals would be reasonably likely to be behaviorally harassed (equated to Level B harassment) or to incur AUD INJ of some degree (equated to Level A harassment).

Level B Harassment

—Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source or exposure context (

e.g.,

frequency, predictability, duty cycle, duration of the exposure, signal-to-noise ratio, distance to the source), the environment (

e.g.,

bathymetry, other noises in the area, predators in the area), and the receiving animals (

e.g.,

hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict (

e.g.,

Southall

et al.,

2007, 2021; Ellison

et al.,

2012). Based on the best scientific information available and the practical need to use a threshold based on a metric that is both predictable and measurable for most activities, NMFS typically uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS generally predicts that marine mammals are likely to be behaviorally harassed in a manner considered to be Level B harassment when exposed to underwater anthropogenic noise above root-mean-squared pressure received levels (RMS SPL) of 120 dB re 1 μPa for continuous (

e.g.,

vibratory pile driving, drilling) and above RMS SPL 160 dB re 1 μPa for non-explosive impulsive (

e.g.,

seismic airguns) or intermittent (

e.g.,

scientific sonar) sources. Generally speaking, Level B harassment estimates based on these behavioral harassment thresholds are expected to include any likely takes by TTS as, in most cases, the likelihood of TTS occurs at distances from the source less than those at which behavioral harassment is likely. TTS of a sufficient degree can manifest as behavioral harassment, as reduced hearing sensitivity and the potential reduced opportunities to detect important signals (

e.g.,

conspecific communication, predators, prey) may result in changes in behavior patterns that would not otherwise occur.

The POA's planned activity includes the use of continuous (vibratory pile driving) and intermittent (impact pile driving) noise sources, and therefore, the RMS SPL thresholds of 120 and 160 dB re 1 μPa are applicable.

Level A Harassment

—NMFS' Updated Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 3.0; NMFS, 2024) identifies dual criteria to assess AUD INJ (Level A harassment) to five different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (

i.e.,

impulsive or non-impulsive). These thresholds are provided in the tables below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS' 2024 Updated Technical Guidance, which may be accessed at:

https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

The POA's planned activity includes the use of impulsive (impact pile driving) and non-impulsive (vibratory driving) sources.

Table 3—NMFS' 2024 Thresholds Identifying the Onset of Auditory Injury (AUD INJ)

Hearing group

AUD INJ acoustic thresholds *

(received level)

Impulsive

Non-impulsive

UNDERWATER:

Low-Frequency (LF) Cetaceans

Cell 1:

L

p,

0-pk,flat

:

222 dB;

L

E,

p,

LF,24h

:

183 dB

Cell 2:

L

E,

p,

LF,24h

:

197 dB.

High-Frequency (HF) Cetaceans

Cell 3:

L

p,

0-pk,flat

:

230 dB;

L

E,

p,

LF,24h

:

193 dB

Cell 4:

L

E,

p,

HF,24h

:

201 dB.

Very High-Frequency (VHF) Cetaceans

Cell 5:

L

p,

0-pk,flat

:

202 dB;

L

E,

p,

VHF,24h

:

159 dB

Cell 6:

L

E,

p,

VHF,24h

:

181 dB.

Phocid Pinnipeds (PW) (Underwater)

Cell 7:

L

p,

0-pk.flat

:

223 dB;

L

E,

p,

PW,24h

:

183 dB

Cell 8:

L

E,

p,

PW,24h

:

195 dB.

Otariid Pinnipeds (OW) (Underwater)

Cell 9:

L

p,

0-pk,flat

:

230 dB;

L

E,

p,

OW,24h

:

185 dB

Cell 10:

L

E,

p,

OW,24h

:

199 dB.

IN-AIR:

Phocid Pinnipeds (PA) (In-Air)

Cell 11:

L

p,

0-pk.flat

:

162 dB;

L

E,

p,

PA,24h

:

140 dB

Cell 12:

L

E,

p,

PA,24h

:

154 dB.

Otariid Pinnipeds (OA) (In-Air)

Cell 13:

L

p,

0-pk,flat

:

177 dB;

L

E,

p,

OA,24h

:

163 dB

Cell 14:

L

E,

p,

OA,24h

:

177 dB.

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be considered.

Note:

Peak sound pressure (

L

pk

) has a reference value of 1 µPa, and cumulative sound exposure level (

L

E

) has a reference value of 1µPa

2

s. In this table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI, 2013). However, peak sound pressure is defined by ANSI as incorporating frequency weighting, which is not the intent for NMFS' 2018 Technical Guidance. Hence, the subscript “flat” is being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be exceeded in a multitude of ways (

i.e.,

varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be exceeded.

Ensonified Area

Here, we describe operational and environmental parameters of the activity that are used in estimating the area ensonified above the acoustic thresholds, including source levels and transmission loss coefficient.

The sound field in the CTR project area is the existing background noise plus additional construction noise from the CTR project. Marine mammals are expected to be affected via sound generated by the primary components of the CTR project (

i.e.,

impact pile removal and vibratory pile installation and removal). Calculation of the area ensonified by the pile driving activities is dependent on the background sound levels at the CTR project site, the source levels of the activities, and the estimated transmission loss coefficients for the activities at the site. These factors are addressed in order, below.

Background Sound Levels at the Port of Alaska

—As discussed in the Specified Geographic Region section of the proposed rule (89 FR 85686, October 28, 2024), the POA is an industrial facility in a location with high levels of commercial vessel traffic, port operations (including dredging), and extreme tidal flow. Previous measurements of background noise at the POA have recorded a background SPL of 122.2 dB RMS (Austin

et al.,

2016). NMFS concurs that this SPL reasonably represents background noise near the CTR project area, and therefore, we have used 122.2 dB RMS as the threshold for Level B harassment (instead of 120 dB RMS).

Sound Source Levels of CTR Activities.

The intensity of pile driving sounds is greatly influenced by factors such as the type of piles (

e.g.,

material and diameter), hammer type, and the physical environment (

e.g.,

sediment type) in which the activity takes place. In order to calculate the distances to the Level A harassment and the Level B harassment sound thresholds for the methods and piles being used in this project, we used acoustic monitoring data from sound source verification studies (both at the POA and elsewhere) to develop proxy source levels for the various pile types, sizes and methods (tables 9 and 10).

The POA collected sound measurements during pile installation and removal for 3 seasons (Austin

et al.

2016; Illingworth & Rodkin (I&R) 2021a, 2021b); a summary of these data and findings can be found in appendix A of the POA's application.

Vibratory Driving

—NMFS concurs that the source levels in the POA's LOA application for vibratory installation and removal of all pile types are appropriate to use for calculating harassment isopleths for the POA's proposed CTR activities (tables 4 and 5). The sound levels for vibratory removal are based on an analysis done for the POA's NES1 IHA (89 FR 2832, January 14, 2024) and are partially based on sound source verification data measured at the POA during the PCT project (Illingworth & Rodkin, 2021a). Interestingly, the analyzed RMS SPL for the unattenuated vibratory removal of 24-in (61-cm) piles was much louder than the unattenuated vibratory removal of 36-in piles (91-cm), and even louder than the unattenuated vibratory installation of 24-in piles. Illingworth & Rodkin (2023) suggest that at least for data recorded at the POA, the higher 24-in (61-cm) removal levels are likely due to the piles being removed at rates of 1,600 to 1,700 revolutions per minute (rpm), while 36-in (91-cm) piles, which are significantly heavier than 24-in (61-cm) piles), were removed at a rate of 1,900 rpm. The slower rates combined with the lighter piles would cause the hammer to easily “jerk” or excite the 24-in (61-cm) piles as they were extracted, resulting in a louder rattling sound and louder sound levels. This did not occur for the 36-in (91-cm) piles, which were considerably heavier due to increased diameter, longer length, and greater thickness.

The TPP found that for vibratory installation of 48-in piles, an air bubble curtain provided about a 9-dB reduction at 10 m. An 8-dB reduction at close-in positions was estimated for vibratory pile driving that occurred during the PCT project in 2021 (I&R 2021b). The PCT 2020 measurements indicated 2 to 8 dB reduction for the 48-in piles at 10 m, but no apparent broadband reduction was found in the far-field at about 2,800 m (I&R 2021a). Far-field sound levels were characterized by very low frequency sound at or below 100 Hz, causing broadband measurements to remain above the ambient RMS level at approximately 2.8km from the source. However, levels at frequencies above 100 Hz were effectively reduced by the bubble curtain system. Because CIBW are most sensitive to frequencies over 100 Hz, NMFS considers the use of bubble curtains during vibratory driving to be a useful mitigation measure for CIBW.

Based on the aforementioned measurements conducted at POA, for vibratory driving during the CTR project, it is assumed that a well-designed and robust bubble curtain system will achieve a mean reduction of 7 dB at the source for 72-in piles, which are the only pile type for which site-specific measurements are unavailable. Bubble curtains will also reduce sound levels at frequencies over 100 Hz at longer ranges. The POA will use a bubble curtain when water depth is greater than 3 m during vibratory installation of all permanent (72-in) piles during all months of construction. The POA may, at its discretion, employ bubble curtains during vibratory driving of temporary piles to reduce the size of the required shutdown zones.

Impact Driving

—NMFS concurs that the source levels proposed by the POA for impact installation of all pile types are appropriate to use for calculating harassment isopleths for the POA's planned CTR activities (tables 4 and 5). Impact driving of temporary piles (24-in and 36-in piles) is not currently planned; however, in the unlikely event that vibratory driving is insufficient to stabilize a temporary pile, impact driving may be necessary. Sound source verification studies at the POA during the PCT project did not measure unattenuated impact driving of 24-in or 36-in piles; therefore, proxy sound levels from Navy (2015) are used.

The TPP measured reductions of 9 to 12 dB for a 48-in pile installed with an impact hammer using a confined air bubble curtain. The PCT 2020 measurements (I&R 2021a) found reductions of about 10 dB when comparing the attenuated conditions that occurred with that project to unattenuated conditions for the TPP. The TPP did not report the reduction in sound levels in the acoustic far field; however, the computed distances to 125 dB RMS isopleths were essentially reduced by half with the bubble curtain (from 1,291 to 698 m).

It is currently unclear whether the POA's planned bubble curtain system for the CTR project will be confined or unconfined; confined systems are typically more effective, especially in sites like Knik Arm, with high current velocity. Therefore, for impact pile installation for the CTR project, it is assumed that a well-designed and robust bubble curtain system will achieve a mean reduction of 7 dB from the source. The POA plans to use a bubble curtain system on all permanent piles in all months, which will be installed with both vibratory and impact hammers. The bubble curtain by necessity will be installed around each permanent pile as it is moved into position, and therefore, the bubble curtain will be available as a mitigation measure to reduce sound levels throughout each driving event for permanent 72-in piles when water depth is greater than 3 m. To account for piles driven in water less than 3 m deep, NMFS has estimated approximately 0.5 unattenuated 72-in piles will be driven (approximately 43 minutes of impact driving and 5 minutes of vibratory driving) each month.

Concurrent Activities

—The POA plans to concurrently operate up to 2 hammers to install or extract piles at different parts of the CTR project site, in order to reduce the need for pile driving during months of high CIBW presence. When 2 noise sources have overlapping sound fields, the sources are considered additive and combined using the rules of dB addition. For addition of 2 simultaneous sources, the difference between the 2 sound source levels is calculated, and if that difference is between 0 and 1 dB, 3 dB are added to the higher sound source levels; if the difference is between 2 and 3 dB, 2 dB are added to the highest sound source levels; if the difference is between 4 and 9 dB, 1 dB is added to the highest sound source levels; and with differences of 10 or more dB, there is no addition. For two simultaneous sources of different type (

i.e.,

impact and vibratory driving), there is no sound source addition. Possible concurrent scenarios and the predicted source values and transmission loss coefficients for these combinations are shown in table 6.

Transmission Loss

—For all piles driven with an active bubble curtain (

i.e.,

“attenuated” impact and vibratory

driving), and for unattenuated impact installation, the POA proposed to use 15 as the

TL

coefficient, meaning they assume practical spreading loss (

i.e.,

the POA assumes

TL

= 15*Log

10

(range)); NMFS concurs with this value and has assumed practical spreading loss for all (attenuated impact and vibratory) driving and unattenuated impact driving.

The

TL

coefficient that the POA proposed for unattenuated vibratory installation and removal of piles is 16.5 (

i.e., TL

= 16.5*Log

10

(range)). This value is an average of measurements obtained from 2, 48-in (122-cm) piles installed via an unattenuated vibratory hammer in 2016 (Austin

et al.,

2016). To assess the appropriateness of this

TL

coefficient to be used for the CTR project, NMFS examined and analyzed additional

TL

measurements recorded at the POA. This includes a

TL

coefficient of 22 (deep hydrophone measurement) from the 2004 unattenuated vibratory installation of one 36-in (91-cm) pile at Port MacKenzie, across Knik Arm from the POA (Blackwell, 2005), as well as

TL

coefficients ranging from 10.3 to 18.2 from the unattenuated vibratory removal of 24-in (61-cm) and 36-in (91-cm) piles and the unattenuated vibratory installation of one 48-in (122-cm) pile at the POA in 2021 (I&R 2021, 2023). To account for statistical interdependence due to temporal correlations and equipment issues across projects, values were averaged first within each individual project, and then across projects. The mean and median value of the measured

TL

coefficients for unattenuated vibratory piles in Knik Arm by project are equal to 18.9 and 16.5, respectively. NMFS therefore used the project median

TL

coefficient of 16.5 during unattenuated vibratory installation and removal of all piles during the CTR project. This value is representative of all unattenuated vibratory measurements in the Knik Arm,

i.e.,

including data from POA and Port MacKenzie. Further, 16.5 is the mean of the 2016 measurements, which were made closer to the CTR project area than other measurements and were composed of measurements from multiple directions (both north and south/southwest).

In certain scenarios, the POA may perform concurrent vibratory driving of 2 piles. The POA proposed, and NMFS concurs, that in the event that both piles are unattenuated, the

TL

coefficient will be 16.5; if both piles are attenuated, the

TL

coefficient will be 15. In the event that 1 pile is attenuated and 1 is unattenuated, the POA proposed a

TL

coefficient of 15.75 to be used in the acoustic modeling. NMFS evaluated the contributions of one attenuated and one unattenuated vibratory-driven pile to the sound field (assuming a 7-dB reduction in source level due to the bubble curtain for the attenuated source) and determined that the unattenuated source would likely dominate the received sound field. Therefore, the POA's proposed

TL

coefficient is conservative, and NMFS concurs with this value.

Table 4—Summary of Unattenuated In-Water Pile Driving Proxy Levels

[at 10 m]

Vibratory hammer

Method and pile type

dB RMS

TL

coefficient

Data source for source levels

24-in steel installation

161

16.5

U.S. Navy 2015.

24-in steel removal

169

NMFS average 2023; see 89 FR 2832.

36-in steel installation

166

U.S. Navy 2015.

36-in steel removal

159

NMFS average 2023; see 89 FR 2832.

72-in steel

171

I&R 2003, unpublished data for Castrol Oil berthing dolphin in Richmond, CA.

Impact hammer

dB RMS

dB SEL

dB peak

TL

coefficient

Data source for source levels

24-in steel

193

181

210

15.0

U.S. Navy 2015.

36-in steel

193

184

211

U.S. Navy 2015.

72-in steel

203

191

217

I&R model. Estimate based on interpolation of data for piles 24 to 144 in diameter.

Table 5—Summary of Attenuated In-Water Pile Driving Proxy Levels

[at 10 m]

Vibratory hammer

Method and pile type

dB RMS

TL

coefficient

Reference for proxy levels

24-in steel installation

158.5

15.0

I&R 2021a (measured).

24-in steel removal

157

I&R 2021a (measured).

36-in steel installation

160.5

I&R 2021a, 2021b (measured).

36-in steel removal

154

I&R 2021a (measured).

72-in steel

164

Assumed 7-dB reduction supported by I&R 2021a.

Impact hammer

dB RMS

dB SEL

dB peak

TL

coefficient

Reference for proxy levels

24-in steel

186

174

203

15.0

Assumed 7-dB reduction supported by I&R 2021a.

36-in steel

186

177

204

Assumed 7-dB reduction supported by I&R 2021a.

72-in steel

196

184

210

Assumed 7-dB reduction supported by Caltrans Compendium (2020).

Table 6—Source Values for Potential Concurrent Driving Scenarios

1

Activity

Method

Pile type/size

2

Attenuated or unattenuated

Proxy source value

dB RMS

dB SEL

dB peak

TL

coefficient

# Piles

per day

3

Concurrent Driving

(2 sources)

Vibratory/Vibratory

36-in and 36-in

Attenuated/Attenuated

163.5

15

8

Attenuated/Unattenuated

169

15.75

8

Unattenuated/Unattenuated

171

16.5

8

Vibratory/Impact

1

36in and 72in

Attenuated/Attenuated

166

15

7

Unattenuated/Attenuated

169

15.75

7

36in and 72in

Attenuated/Attenuated

160.5/196

-/184

-/210

15/15

8

Unattenuated/Attenuated

166/196

-/184

-/210

16.5/15

7

1

Concurrent vibratory and impact driving source values and TL coefficients are the same as for the piles driven individually (shown in tables 4 and 5), with no adjustments for concurrent driving. The Level A harassment isopleths would be determined by the calculated impact pile driving isopleths, and Level B harassment isopleth would be generated by vibratory pile driving.

2

POA may elect to use either 36-in or 24-in temporary piles; as 36-in piles are more likely and estimated to have larger ensonified areas, we have used these piles in our analyses of concurrent activities.

3

Piles per day were calculated as the maximum daily number of each type of pile (24-in and 36-in = 4 piles per hammer per day; 72-in piles = 3 piles per day) with complete overlap for 45 minutes of driving with the largest possible combined source value, a scenario that would over-estimate duration of noise production given the estimated time required to drive 72-in piles with a vibratory hammer (10 minutes).

Estimated Harassment Isopleths

—All estimated Level B harassment isopleths are reported in table 10. At POA, Level B harassment isopleths from the CTR project will be limited in some cases to less than the estimated value by the coastline along Knik Arm along and across from the CTR project site. The maximum predicted isopleth distance for a single pile is 9,069 m during vibratory installation of unattenuated 72-in (182-cm) steel pipe piles. For concurrent driving the maximum isopleth distance is 9,363 m during vibratory driving of two unattenuated 24- or 36-in piles or during vibratory driving of one attenuated (24-, 36-, or 72-in) and one unattenuated (24- or 36-in) pile (tables 15 and 16).

The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes. We note that because of some of the assumptions included in the methods underlying this optional tool, we anticipate that the resulting isopleth estimates are typically going to be overestimates of some degree, which may result in an overestimate of potential take by Level A harassment. However, this optional tool offers the best way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources, such as pile driving, the optional User Spreadsheet tool predicts the distance at which, if a marine mammal remained at that distance for the duration of the activity, it would be expected to incur AUD INJ. Inputs used in the optional User Spreadsheet tool and the resulting estimated isopleths are reported in tables 7 through 10, below.

Table 7—NMFS User Spreadsheet Inputs for 72-in Permanent Piles

Impact pile driving

Attenuated

Unattenuated

1

Vibratory pile driving

Attenuated

Unattenuated

2

Spreadsheet Tab Used

E.1) Impact pile driving

A.1) Non-Impul, Stat, Cont.

Source Level

184 dB SEL

191 dB SEL

164 dB RMS

171 dB RMS

Transmission Loss Coefficient

15

15

15

16.5

Weighting Factor Adjustment (kHz)

2

2.5

Time to install single pile (minutes)

—

10

Number of strikes per pile

5,743

—

Piles per day

1-3

1

3

Distance of sound pressure level measurement (m)

10

1

To account for piles driven in water less than 3 m deep, NMFS has estimated approximately 0.5 unattenuated 72-in piles will be driven (approximately 43 minutes of impact driving and 5 minutes of vibratory driving) each month.

Table 8—NMFS User Spreadsheet Inputs for Temporary (24- or 36-in) Piles

Vibratory pile driving

24-in (61-cm) steel pipe

Installation

Removal

Atten

Unatten

Atten

Unatten

36-in (91-cm) steel pipe

Installation

Removal

Atten

Unatten

Spreadsheet Tab Used

A.1) Non-Impul, Stat, Cont.

Source Level (dB RMS)

158.5

161

157

169

160.5

166

154

159

Transmission Loss Coefficient

15

16.5

15

16.5

15

16.5

15

16.5

Weighting Factor Adjustment (kHz)

2.5

Time to install or remove single pile (minutes)

30

45

30

45

Number of strikes per pile

—

Piles per day

4

Distance of sound pressure level measurement (m)

10

Impact pile driving

24-in (61-cm) steel pipe

36-in (91-cm) steel pipe

Attenuated

Unattenuated

Attenuated

Unattenuated

Spreadsheet Tab Used

E.1) Impact pile driving

Source Level

174 dB SEL

181 dB SEL

177 dB SEL

184 dB SEL

Transmission Loss Coefficient

15

Weighting Factor Adjustment (kHz)

2

Time to install or remove single pile (minutes)

—

Number of strikes per pile

1,000

Piles per day

1

Distance of sound pressure level measurement (m)

10

Table 9—NMFS User Spreadsheet Inputs for Concurrent Vibratory Driving

24- or 36-in AND 24-in or 36-in

Attenuated/

attenuated

Attenuated/unattenuated

Unattenuated/unattenuated

24- or 36-in AND 72-in

Attenuated/

attenuated

Unattenuated/attenuated

Spreadsheet Tab Used

Non-Impul, Stat, Cont.

Source Level (dB RMS)

163.5

170

172

166

170

Transmission Loss Coefficient

15

15.75

16.5

15

15.75

Weighting Factor Adjustment (kHz)

2.5

Time to install or remove a single pile (minutes)

45

Number of strikes per pile

—

Piles per day

8

7

Distance of sound pressure level measurement (m)

10

Table 10—Calculated Distance of Level A (Based on NMFS' 2024 Updated Technical Guidance) and Level B Harassment Isopleths by Pile Type and Pile Driving Method

Activity

Pile type/size

Attenuated or unattenuated

Level A harassment distance (m)

LF

HF

VHF

PW

OW

Level B

harassment

distance (m)

all hearing

groups

1

Impact

24-in (61-cm)

Unattenuated

732

94

1,133

651

243

1,585

Attenuated

250

32

387

222

83

541

36-in (91-cm)

Unattenuated

1,160

148

1,796

1,031

385

1,585

Attenuated

397

51

613

352

132

541

72-in (182-cm)

Unattenuated

10,896

1,390

16,861

9,679

3,608

7,356

Attenuated (1 pile per day)

3,720

474.7

5,757

3,305

1,232

2,512

Attenuated (2 piles per day)

5,906

753.5

9,139

5,246

1,956

Attenuated (3 piles per day)

7,739

987.4

11,976

6,875

2,563

Vibratory Installation

24-in (61-cm)

Unattenuated

14.1

5.9

11.8

17.8

6.6

2,247

Attenuated

10

3.8

8.1

12.8

4.3

2,630

36-in (91-cm)

Unattenuated

28.4

11.9

23.6

35.7

13.3

4,514

Attenuated

13.6

5.2

11.1

17.5

5.9

3,575

72-in (182-cm)

Unattenuated

24.6

10.3

20.5

31

11.5

9,069

Attenuated

9.2

3.5

7.5

11.9

4

6,119

Vibratory Removal

24-in (61-cm)

Unattenuated

55.2

23.1

45.9

69.5

25.8

6,861

Attenuated

10.4

4

8.5

13.4

4.5

2,089

36-in (91-cm)

Unattenuated

13.7

5.7

11.4

17.2

6.4

1,699

Attenuated

6.6

2.5

5.4

8.4

2.8

1,318

Concurrent Vibratory/Vibratory

36-in AND 36-in

Attenuated/Attenuated

44.7

17.2

36.5

57.5

19.4

5,667

Attenuated/Unattenuated

107.6

43.3

88.8

136.9

48.5

9,363

Unattenuated/Unattenuated

127.7

53.5

106.3

160.7

59.7

9,069

36-in AND 72-in

Attenuated/Attenuated

60

23.1

49

77.3

26

8,318

Unattenuated/Attenuated

98.9

39.8

81.6

125.8

44.6

9,363

Concurrent Vibratory/Impact

36-in AND 72-in

Attenuated/Attenuated (1 pile per day)

3,720

474.7

5,757

3,305

1,232

3,575

Attenuated/Attenuated (2 piles per day)

5,906

753.5

9,139

5,246

1,956

Attenuated/Attenuated (3 piles per day)

7,739

987.4

11,976

6,875

2,563

Unattenuated/Attenuated (1 pile per day)

3,720

474.7

5,757

3,305

1,232

4,514

Unattenuated/Attenuated (2 piles per day)

5,906

753.5

9,139

5,246

1,956

Unattenuated/Attenuated (3 piles per day)

7,739

987.4

11,976

6,875

2,563

1

Distances to thresholds are as modeled; however, interaction with shorelines would truncate zones. See figures 6-1 through 6-10 in the POA's application for further details.

Marine Mammal Occurrence

In this section, we provide information about the occurrence of marine mammals, including density or other relevant information, which informed the take calculations. Available information regarding marine mammal occurrence and abundance in the vicinity of the POA includes monitoring data from the PCT and SFD projects. These programs produced a unique and comprehensive data set of marine mammal sightings and for CIBWs, locations and movements near the POA (61N Environmental, 2021, 2022a, 2022b; Easley-Appleyard and Leonard, 2022). This is the most current data set available for Knik Arm. During the PCT and SFD projects, the POA's marine mammal monitoring programs included 11 PSOs working from four elevated, specially designed monitoring stations located along a 9-km stretch of coastline surrounding the POA. The number of days data was collected varied among years and projects, with 128 days during PCT Phase 1 in 2020, 74 days during PCT Phase 2 in 2021, and 13 days during SFD in 2022 (see tables 6-15 in the POA's application for additional information regarding CIBW monitoring data). PSOs during these projects used 25-power “big-eye” and hand-held binoculars to detect and identify marine mammals and theodolites to track movements of CIBW groups over time and collect location data while they remained in view.

These POA monitoring programs were supplemented in 2021 with a NMFS-funded visual marine mammal monitoring project that collected data during non-pile driving days during PCT Phase 2 (Easley-Appleyard and Leonard, 2022). NMFS replicated the POA monitoring efforts, as feasible, including use of 2 of the POA's monitoring platforms, equipment (Big Eye binoculars, theodolite, 7x50 reticle binoculars), data collection software, monitoring and data collection protocol, and observers; however, the NMFS-funded program utilized only 4 PSOs and 2 observation stations along with shorter (4- to 8-hour) observation periods compared to PCT or SFD data collection, which included 11 PSOs, 4 observation stations, and most observation days lasting close to 10 hours. Despite the differences in effort, the NMFS dataset fills in gaps during the 2021 season and is thus valuable in this analysis. NMFS' PSO's monitored for 231.6 hours on 47 non-consecutive days in July, August, September, and October.

Density data are not available for any of the relevant species in this area; therefore, we have used reasonable yearly, monthly, or hourly occurrence estimates based on the previous POA monitoring datasets for all species. Table 11 shows the estimated occurrence rates for non-CIBW species at the POA; descriptions are provided in the text below.

Table 11—Estimated Occurrence for Non-CIBW Species at the POA

Species

Timeframe

Estimated

occurrence rates

Estimated

annual occurrence

Estimated 5-year

occurrence

Gray whale

Yearly

6/year

6

30

Humpback whale

4/year

4

20

Killer whale

6/year

6

30

Steller sea lion

9/year

9

45

Harbor porpoise

Hourly

0.15/hour

1,314

6,570

Harbor seal

1/hour

8,760

43,800

Gray Whale

Sightings of gray whales in the CTR project area are rare. Few, if any, gray whales are expected to approach the CTR project area. However, based on three separate sightings of single gray whales near the POA in 2020 and 2021 (61N Environmental, 2021, 2022a; Easley-Appleyard and Leonard, 2022), the POA anticipates that up to 6 individuals could occur within estimated harassment zones each year during CTR project activities.

Humpback Whale

Sightings of humpback whales in the CTR project area are rare, and few, if any, humpback whales are expected to approach the CTR project area. However, there have been previous observations of humpback whales near the POA. Based on the 2 sightings in 2017 of what was likely a single individual at the Anchorage Public Boat Dock at Ship Creek (ABR, Inc., 2017) south of the CTR project area, the POA estimated that 6 humpback whales per year may occur in the vicinity of the CTR project. However, given the maximum number of humpback whales observed within a single construction season was two (in 2017), NMFS instead anticipates that only up to 4 humpback whales could be exposed to project-related underwater noise per year during the CTR project.

Killer Whale

Few, if any, killer whales are expected to approach the CTR project area. No killer whales were sighted during previous monitoring programs for POA construction projects, including the 2016 TPP, 2020 PCT, and 2022 SFD projects (Prevel-Ramos

et al.,

2006; Markowitz and McGuire, 2007; Cornick and Saxon-Kendall, 2008, 2009; Cornick

et al.,

2010, 2011; ICRC, 2009, 2010, 2011, 2012; Cornick and Pinney, 2011; Cornick and Seagars, 2016; 61N Environmental, 2021, 2022b), except during PCT construction in 2021, when 2 killer whales were sighted (61N Environmental, 2022a). Previous sightings of transient killer whales have documented pod sizes in upper Cook Inlet between 1 and 6 individuals (Shelden

et al.,

2003). The POA estimates, and NMFS concurs, that 1 pod (assumed to be 6 individuals) could occur within the CTR project area during CTR project activities each year.

Harbor Porpoise

Monitoring data recorded from 2005 through 2022 were used to evaluate hourly sighting rates for harbor porpoises in the proposed CTR area (see table 4-3 in the POA's application). During most years of monitoring, no harbor porpoises were observed. However, there has been an increase in harbor porpoise sightings in upper Cook Inlet in recent decades (

e.g.,

61N Environmental, 2021, 2022a; Shelden

et al.,

2014). The highest sighting rate for any recorded year during in-water pile installation and removal was an average of 0.037 harbor porpoises per hour during PCT construction in 2021, when observations occurred across most months. Given the uncertainty around harbor porpoise occurrence at the POA and potential that occurrence is increasing, the POA calculated requested takes using a sighting rate of 0.5 harbor porpoises per hour. For the recent NES1 project (88 FR 76576, November 6, 2023), NMFS estimated that a more realistic sighting rate would be closer to approximately 0.07 harbor porpoises per hour (the 2021 rate of 0.037 harbor porpoises per hour doubled). However, the sizes of the ensonified areas for the NES1 project are much smaller than those predicted for the CTR project. Based on the larger ensonified areas, which more closely resemble the observable area from the PCT project, the cryptic nature of the species, and the potential for increased occurrence of harbor porpoise in and around upper Cook Inlet, NMFS estimates that approximately 0.15 harbor porpoises per hour (four times the maximum observed 2021 rate of 0.037 per hour) may be observed near the CTR area during the 5 years covered under this rulemaking.

Steller Sea Lion

Steller sea lions are anticipated to occur in low numbers within the CTR project area as summarized in the Description of Marine Mammals in the Area of Specified Activities section. Similar to the approach used above for harbor porpoises, the POA used previously recorded sighting rates of Steller sea lions near the POA to estimate requested take for this species. During SFD construction in May and June of 2022, the hourly sighting rate for Steller sea lions was 0.028. The hourly sighting rate for Steller sea lions in 2021, the most recent year with observations across most months, was approximately 0.01. The highest number of Steller sea lions that have been observed during the 2020-2022 monitoring efforts at the POA was 9 individuals (8 during PCT Phase 1 monitoring and 1 during NMFS' 2021 monitoring).

Recent counts of sightings of Steller sea lions around the POA may include multiple re-sights of single individuals. For instance, in 2016, Steller sea lions were observed on 2 separate days. On May 2, 2016, 1 individual was sighted, while on May 25, 2016, there were 5 Steller sea lion sightings within a 50-minute period, and these sightings occurred in areas relatively close to one another (Cornick and Seagars, 2016). Given the proximity in time and space, it is believed these 5 sightings were of the same individual sea lion. The POA is concerned that multiple re-sights of a single individual within a day may overestimate the true number of individuals exposed to sound levels at or above harassment thresholds over the course of the CTR project. Therefore, given the uncertainty around Steller sea lion occurrence at the POA and potential that occurrence is increasing, the POA estimated that approximately 0.14 Steller sea lions per hour (the May and June 2022 rate of 0.028 Steller sea lions per hour multiplied by a factor of 5) may be observed near the proposed CTR project areas per hour of hammer use. However, the highest number of Steller sea lion sightings during the 2020-2022 monitoring efforts at the POA was 9 (8 during PCT Phase 1 monitoring and 1 during NMFS' 2021 monitoring).

Given the POA's estimate assumes a higher Steller sea lion sighting rate (0.14) than has been observed at the POA and results in an estimate that is more than double the maximum number of Steller sea lions observed in a year, NMFS believes that the sighting rate proposed by the POA overestimates potential exposures of this species. Based on the ensonified areas, which closely resemble the observable area from the PCT project, the potential for re-sightings of individual animals, and the uncertainty around increased occurrence of Steller sea lions in and around upper Cook Inlet, NMFS instead assumes that 9 Steller sea lions (

i.e.,

the maximum number observed in a single year between 2020 and 2022 during projects with similar sized harassment isopleths) could occur within the CTR project area each year during the 5 years covered under this rulemaking.

Harbor Seal

No known harbor seal haulout or pupping sites occur in the vicinity of the POA. In addition, harbor seals are not known to reside in the CTR project area, but they are seen regularly near the mouth of Ship Creek when salmon are running, from July through September. With the exception of newborn pups, all ages and sexes of harbor seals could occur in the CTR project area. Harbor seals often appear curious about onshore activities and may approach closely. The mouth of Ship Creek,

where harbor seals linger, is about 1,500 m from the southern end of the CTR project area.

The POA evaluated marine mammal monitoring data to calculate hourly sighting rates for harbor seals in the CTR project area (see table 4-1 in the POA's application). Of the 524 harbor seal sightings in 2020 and 2021, 93.7 percent of the sightings were of single individuals; only 5.7 percent of sightings were of 2 individual harbor seals, and only 0.6 percent of sightings reported 3 harbor seals. Sighting rates of harbor seals were highly variable and appeared to have increased during monitoring between 2005 and 2022. It is unknown whether any potential increase was due to local population increases or habituation to ongoing construction activities. The highest individual hourly sighting rate recorded for the previous year was used to quantify take of harbor seals for in-water pile installation and removal associated with CTR. This occurred in 2021 during PCT Phase 2 construction, when harbor seals were observed from May through September. A total of 220 harbor seal sightings were observed over 734.9 hours of monitoring, at an average rate of 0.30 harbor seal sightings per hour. The maximum monthly sighting rate occurred in September 2020 and was 0.51 harbor seal sightings per hour. Based on these data, the POA estimated, and NMFS concurs, that approximately 1 harbor seal (the maximum monthly sighting rate (0.51) rounded up) may be observed near the CTR project per hour of hammer use.

Beluga Whale

CIBWs are regular and frequent visitors to Knik Arm, sometimes passing by the POA multiple times a day, as documented by the previous PAMP monitoring projects (61N Environmental, 2021, 2022a, 2022b). Distances from CIBW sightings to the CTR project site from the POA and NMFS-funded monitoring programs ranged from less than 10 m up to nearly 15 km. The robust marine mammal monitoring programs in place at the POA from 2020 through 2022 located, identified, and tracked CIBWs at greater distances from the proposed project site than previous monitoring programs (

i.e.,

Kendall and Cornick, 2015) and has contributed to a better understanding of CIBW movements in upper Cook Inlet (

e.g.,

Easley-Appleyard and Leonard, 2022).

For the NES1 project, NMFS and the POA collaboratively developed a new sighting rate methodology that incorporates a spatial component for CIBW observations, which allows for more accurate estimation of potential take of CIBWs (89 FR 2832, January 14, 2024). We have used this same methodology in the analysis of estimated CIBW incidental take during the CTR project. A detailed description of the differences from the sighting-rate methods used in the PCT and SFD projects can be found in the proposed rule for the NES1 project (88 FR 76576, November 6, 2023).

During the POA's and NMFS' marine mammal monitoring programs for the PCT and SFD projects (table 12), PSOs had an increased ability to detect, identify, and track CIBWs groups at greater distances from the project work site when compared with previous years because of the POA's expanded monitoring program as described above. This meant that observations of CIBWs in the 2020-2022 dataset (table 12) include sightings of individuals at distances far outside some of the ensonified areas estimated for the CTR project and at ranges close to the extent of the larger ensonified areas (table 10). Therefore, it would not be appropriate to group all CIBW observations from these datasets into a single sighting rate as was done for the PCT and SFD projects. Rather, CIBW observations were considered in relation to their distance to the CTR project site when determining appropriate sighting rates to use when estimating take for this project. This helped to ensure that the sighting rates used to estimate take are representative of CIBW presence in the estimated ensonified areas.

Table 12—Marine Mammal Monitoring Data Used for CIBW Sighting Rate Calculations

Year

Monitoring type and data source

Number of

CIBW group fixes

Number of

CIBW groups

Number of

CIBWs

2020

PCT: POA Construction Monitoring, 61N Environmental, 2021

2,653

245

987

2021

PCT: NMFS Monitoring, Easley-Appleyard and Leonard, 2022

694

1

109

575

2021

PCT: POA Construction Monitoring, 61N Environmental, 2021, 2022a

1,339

132

517

2022

SFD: POA Construction Monitoring, 61N Environmental, 2022b

151

9

41

2024

NES1: POA Construction Monitoring, 61N Environmental, 2025

4,618

433

1,924

1

This number differs slightly from table 6-8 in the POA's application due to our removal of a few duplicate data points in the NMFS data set.

To incorporate a spatial component into the sighting rate methodology, the POA calculated each CIBW group's closest point of approach (CPOA) relative to the CTR project site. The 2020-2022 and 2024 marine mammal monitoring programs (table 12) enabled the collection, in many cases, of multiple locations of CIBW groups as they transited through Knik Arm, which allowed for track lines to be interpolated for many groups. The 2024 sightings data were received from the POA on March 3, 2024 and have been analyzed according to the same methodologies described in the proposed rule (89 FR 85686, October 28, 2024). The POA used these track lines or single recorded locations in instances where only one sighting location was available to calculate each group's CPOA. CPOAs were calculated in ArcGIS software using the Geographic Positioning System (GPS) coordinates provided for documented sightings of each group (for details on data collection methods, see 61N Environmental, 2021, 2022a, 2022b; 2025; Easley-Appleyard and Leonard, 2022) and the CTR location midpoint, centered on the CTR project site. A CIBW group was defined as a sighting of one or more CIBWs as determined during data collection. The most distant CPOA location to CTR was 12,791 m and the closest CPOA location was 6 m.

The cumulative density distribution of CPOA values represents the percentage of CIBW observations that were within various distances to the CTR project site (figure 1). This distribution shows how CIBW observations differed with distances to the CTR site and was used to infer appropriate distances within which to estimate spatially-derived CIBW sighting rates (figure 1). The POA implemented a piecewise regression model that detected breakpoints (

i.e.,

points within the CPOA data at which statistical properties of the sequence of observational distances changed) in the cumulative density distribution of the CPOA locations, which they proposed

to represent spatially-based sighting rate bins for use in calculating CIBW sighting rates. The POA used the “Segmented” package (Muggeo, 2020) in the R Statistical Software Package (R Core Team, 2022) to determine statistically significant breakpoints in the linear distances of the CIBW data using this regression method (see section 6.5.5.3 of the POA's application for more details regarding this statistical analysis). This analysis identified breakpoints in the CPOA locations at 281, 2,213, 3,149, and 6,639 m (figure 1), differ by between 5.7 and 335 m from the breakpoints identified from the 2020 and 2021 data (

i.e.,

195.7; 2,337; 3,154.7; and 6,973.9 m) in the proposed rule (89 FR 85686, October 28, 2024).

ER15JY25.017

Piecewise regression is a common tool for modeling ecological thresholds (Lopez

et al.,

2020; Whitehead

et al.,

2016; Atwood

et al.,

2016). In a similar scenario to the one outlined above, Mayette

et al.

(2022) used piecewise regression methods to model the distances between two individual CIBWs in a group in a nearshore and a far shore environment. For the POA's analysis, the breakpoints (

i.e.,

281, 2,213, 3,149, and 6,639 m) detect a change in the frequency of CIBW groups sighted and the slope of the line between two points indicates the magnitude of change. A greater positive slope indicates a greater accumulation of sightings over the linear distance (x-axis) between the defining breakpoints, whereas a more level slope (

i.e.,

closer to zero) indicates a lower accumulation of sightings over that linear distance (x-axis) between those defining breakpoints (figure 1; see table 6-16 in the POA's application for the slope estimates for the empirical cumulative distribution function).

The breakpoints identified by the piecewise regression analysis are in agreement with what is known about CIBW behavior in Knik Arm based on recent monitoring efforts (61N Environmental, 2021, 2022a, 2022b, 2025; Easley-Appleyard and Leonard, 2022). Observation location data collected during POA monitoring programs indicate that CIBWs were consistently found in higher numbers in the nearshore areas, along both shorelines, and were found in lower numbers in the center of the Arm. Tracklines of CIBW group movements collected from 2020 to 2022 and 2024 show that CIBWs displayed a variety of movement patterns that included swimming close to shore past the POA on the east side of Knik Arm (defined by breakpoint 1 at 281 m), with fewer CIBWs swimming in the center of Knik Arm (breakpoints 1 to 2, at 281 to 2,213 m). CIBWs commonly swam past the POA close to shore on the west side of Knik Arm, with no CIBWs able to swim farther from the POA in that area than the far shore (breakpoints 2 to 3, at 2,213 to 3,149 m). Behaviors and locations beyond breakpoint 4 (6,639 m) include swimming past the mouth of Knik Arm between the Susitna River area and Turnagain Arm; milling at the mouth of Knik Arm but not entering the Arm; and milling to the northwest of the POA without exiting Knik Arm. The shallowness of slope 5, at distances greater than 6,639 m, could be due to detection falloff from a proximity (distance) bias, which would occur when PSOs are less likely to detect CIBW groups that are farther away than groups that are closer.

The POA, in collaboration with NMFS, used the distances detected by the breakpoint analysis to define 5 sighting rate distance bins for CIBWs in the NES1 project area. Each breakpoint (281, 2,213, 3,149, and 6,639 m, and the complete data set of observations (>6,639 m)) was rounded up to the nearest meter and considered the outermost limit of each sighting rate bin, resulting in 5 identified bins (table 19).

All CIBW observations less than each bin's breakpoint distance were used to calculate that bin's respective monthly sighting rates (

e.g.,

all sightings from 0 to 281 m are included in the sighting rates calculated for bin number 1, all sightings from 0 to 2,213 m are included in the sighting rates calculated for bin number 2, and so on). CTR construction is anticipated to take place in the months of April through November over the 5-year timeframe of this rule; therefore, monthly sighting rates were only derived for these months (table 13).

Table 13—CIBW Monthly Sighting Rates for Different Spatially-Based Bin Sizes

Bin No.

Distance

(m)

CIBW/hour

1

April

May

June

July

August

September

October

November

1

281

0.05

0.04

0.14

0.03

0.97

0.39

0.53

0.02

2

2213

0.32

0.16

0.36

0.11

1.97

1.35

1.18

0.65

3

3149

0.36

0.22

0.47

0.13

2.62

2.01

1.97

0.72

4

6639

0.64

0.31

0.57

0.16

2.88

2.30

2.35

0.73

5

>6639

0.71

0.39

0.58

0.16

2.94

2.35

2.48

0.73

1

Observation hours have been totaled from the PCT 2020 and 2021 programs, the NMFS 2021 data collection effort, and the SFD 2022 program (61N Environmental 2021, 2022a, 2022b, 2025; Easley-Appleyard and Leonard, 2022).

Take Estimation

In this section, we describe how the information provided above was synthesized to produce a quantitative estimate of the take that is reasonably likely to occur and may be authorized.

To quantitatively assess exposure of marine mammals to noise from pile driving activities, we used the occurrence estimate (number/unit of time; tables 11 and 13) and the estimated work hours per year (table 14) to determine the number of animals potentially exposed to an activity. Because the size of the Level A harassment zones may exceed the shutdown zones (see the Mitigation section) and the limits of PSO visibility during impact driving activities, the number of takes by Level A harassment was estimated based on the proportion of work hours allocated to impact pile driving (table 14) for all species except killer whales, which have smaller predicted Level A harassment zones, and CIBWs, which have larger required shutdown zones, described in further detail below.

For killer whales, while unlikely, it is possible that a group could approach the POA from the northern portion of Knik Arm and immediately enter into a Level A harassment zone before PSOs are able to shut down pile driving activities. The POA estimates, and NMFS concurs, that 1 pod (assumed to be 6 individuals) could be taken by Level A harassment over the 5 years of the CTR project.

Table 14—Estimated Predicted Number of Hours of Impact and Vibratory Hammer Use for Each Construction Year

Year

Impact

duration

(hrs)

Vibratory

duration

(hrs)

Total

duration

(hrs)

Proportion of

impact

hammer use

1

98.9

55.0

153.9

0.6

2

87.4

47.9

135.4

0.7

3

38.7

96.5

135.2

0.3

4

87.4

50.4

137.9

0.6

5

81.7

55.5

137.2

0.6

The equation used to calculate estimated take by Level A harassment for species with yearly occurrence estimates is:

Level A harassment estimate = occurrence × proportion of impact hammer use

where occurrence per year is taken from table 11, and proportion of impact hammer use per year from table 14. For species with hourly occurrence estimates, the equation is:

Level A harassment estimate = (hourly occurrence × total duration in hours) × proportion of impact hammer use.

Estimates of take by Level A and Level B harassment for all species are based on the best available data. NMFS will authorize total takes for each species by Level A and Level B harassment over the 5-year period of the proposed ITR as calculated and shown in the relevant tables, with annual take by Level A and Level B harassment for each species not to exceed the maximum annual values shown in tables 15, 16, and 19.

Table 15—Authorized Take by Level A Harassment in Each of the 5 Years and in Total for Non-CIBW Marine Mammal Species in the CTR Project Area

1

Species

Authorized Level A harassment by year

1

2

3

4

5

Total

Gray whale

4

4

2

4

4

18

Humpback whale

3

3

1

3

2

12

Killer whale

6

6

Harbor porpoise

15

13

6

13

12

59

Steller sea lion

6

6

3

6

5

26

Harbor seal

98

88

39

87

82

394

1

Annual take may not be distributed exactly as shown; NMFS authorizes total take over the 5 year construction period, with annual take by Level A harassment for each species not to exceed the maximum annual value shown in years 1-5.

Estimates of take by Level B harassment for non-CIBW species were calculated as the difference between the estimated Level A harassment exposures and total estimated yearly occurrence (either the estimated yearly occurrence from table 15 or calculated as the hourly occurrence from table 11 multiplied by the total yearly duration in table 14) for each stock.

Table 16—Authorized Take by Level B Harassment in Each of the 5 Years and in Total for Non-CIBW Marine Mammal Species in the CTR Project Area

1

Stock

Authorized Level B harassment by year

1

2

3

4

5

Total

Gray whale

2

2

4

2

2

12

Humpback whale

1

1

3

1

2

8

Killer whale

6

6

6

6

6

30

Harbor porpoise

8

7

14

8

8

45

Steller sea lion

3

3

6

3

4

20

Harbor seal

55

47

96

51

55

304

1

Annual take may not be distributed exactly as shown; NMFS authorizes total take over the 5 year construction period, with annual take by Level A and Level B harassment not to exceed the sum of the maximum annual values shown in years 1-5 in tables 15 and 16.

Beluga Whale

Potential exposures above harassment thresholds of CIBWs, which we equate with takes, were calculated by multiplying the total number of vibratory installation or removal hours per month for each sized/shaped pile based on the anticipated construction schedule (see table 2 in the proposed rule) with the corresponding sighting rate month and sighting rate distance bin (table 17). For example, the Level B harassment isopleth distance for the vibratory installation of 36-in (91-cm) piles is 4,514 m, which falls within bin number 4 (table 17). Therefore, take for this activity was calculated by multiplying the total number of hours estimated each month to install 36-in piles via a vibratory hammer by the monthly CIBW sighting rates calculated for bin number 4 (table 17). The resulting estimated CIBW exposures were totaled for all activities in each month (table 18).

In their calculation of CIBW take, the POA assumed that only 36-in template piles will be installed (rather than 24-in) and removed during the CTR project. If 24-in piles are used for temporary stability template piles, it would be assumed that the potential impacts of this alternate construction scenario and method on marine mammals are fungible (

i.e.,

that potential impacts of installation and removal of 24-in steel pipe piles would be similar to the potential impacts of installation and removal of 36-in steel pipe piles). While removal of 24-in piles may be louder than removal of 36-in piles (tables 9 and 10), installation would be significantly quieter. Given the number of piles to be installed and extracted using vibratory methods, overall impacts from 36-in piles are expected to be greater than those from 24-in piles.

Table 17—Allocation of Each Level B Harassment Isopleth to a Sighting Rate Bin and CIBW Monthly Sighting Rates for Different Pile Sizes and Hammer Types

Activity

Level B

isopleth

distance

(m)

Sighting

rate bin No. and

distance

CIBWs/hour

Apr

May

Jun

Jul

Aug

1

Sep

1

Oct

1

Nov

Unattenuated Values (without the use of a bubble curtain)

36-in Vibratory Removal

1

2

1,699

2 (2,213 m)

0.32

0.16

0.36

0.11

1.97

1.35

1.18

0.65

36-in Vibratory Installation

1

2

4,514

4 (6,639 m)

0.64

0.31

0.57

0.16

2.88

2.30

2.35

0.73

72-in Vibratory Installation

3

9,069

5 (>6,639)

0.71

0.39

0.58

0.16

2.94

2.35

2.48

0.73

Concurrent 36-in AND 36-in Vibratory Installation

9,069

Concurrent 36-in AND 36-in OR 72-in Vibratory Installation

4

9,363

36-in Impact Installation

1

2

1,585

2 (2,213 m)

0.32

0.16

0.36

0.11

1.97

1.35

1.18

0.65

72-in Impact Installation

3

7,356

5 (>6,639)

0.71

0.39

0.58

0.16

2.94

2.35

2.48

0.73

Attenuated Values (with the use of a bubble curtain)

36-in Vibratory Removal

2

1,318

2 (2,213)

0.32

0.16

0.36

0.11

1.97

1.35

1.18

0.65

36-in Vibratory Installation

2

3,575

4 (6,639 m)

0.64

0.31

0.57

0.16

2.88

2.30

2.35

0.73

72-in Vibratory Installation

3

6,119

Concurrent 36-in AND 36-in Vibratory Installation

5,667

Concurrent 36-in AND 72-in Vibratory Installation

8,318

5 (>6,639)

0.71

0.39

0.58

0.16

2.94

2.35

2.48

0.73

36-in Impact Installation

1

2

541

2 (2,213)

0.32

0.16

0.36

0.11

1.97

1.35

1.18

0.65

72-in Impact Installation

2,512

3 (3,149 m)

0.36

0.22

0.47

0.13

2.62

2.01

1.97

0.72

1

Unattenuated vibratory and impact driving of permanent piles during the months of August through October would be limited to the minimum possible number of piles that must be driven in-water in depths <3 m.

2

Unattenuated and attenuated vibratory installation of 36-in temporary piles both result in bin 4; vibratory removal of this pile type results in bin 2 in both attenuated and unattenuated conditions. Unattenuated and attenuated impact pile driving of 36-in piles results in bin 2 in both conditions.

3

Unattenuated vibratory and impact installation of permanent (72-in) piles will be minimized to the extent possible by driving as many piles as possible in the dry for all months of the construction seasons. To account for piles driven in water less than 3 m deep, NMFS has estimated approximately 0.5 unattenuated 72-in piles will be driven (approximately 43 minutes of impact driving and 5 minutes of vibratory driving) each month. Impact driving (attenuated and unattenuated) results in Bin 2; vibratory driving (attenuated and unattenuated) results in Bin 5.

4

Both concurrent driving of 2 temporary piles (1 attenuated, 1 unattenuated) and 1 temporary (unattenuated) and 1 permanent (attenuated) piles result in a Level B harassment isopleth of 9,363 m.

For the PCT (85 FR 19294, April 6, 2020), SFD (86 FR 50057, September 7, 2021), and NES1 (89 FR 2832, January 14, 2024) projects, NMFS accounted for the implementation of mitigation measures (

e.g.,

shutdown procedures implemented when CIBWs entered or approached the estimated Level B harassment zone) by applying an adjustment factor to CIBW take estimates. This was based on the assumption that some Level B harassment takes would likely be avoided based on required shutdowns for CIBWs at the Level B harassment zone isopleths (see the Mitigation section for more information). For the PCT project, NMFS compared the number of observations of CIBW within estimated harassment zones at the POA to the number of authorized takes for previous projects from 2008 to 2017 and found the percentage ranged from 12 to 59 percent with an average of 36 percent (85 FR 19294, April 6, 2020). NMFS then applied the highest percentage of previous potentially realized takes (

i.e.,

number of CIBWs observed within estimated Level B harassment zones; 59 percent during the 2009-2010 season) to ensure potential takes of CIBWs were fully evaluated. In doing so, NMFS assumed that approximately 59 percent of the takes calculated could be realized during PCT and SFD construction (85 FR 19294, April 6, 2020; 86 FR 50057, September 7, 2021) and that 41 percent of the calculated CIBW Level B harassment takes would be avoided by successful implementation of required mitigation measures.

The POA calculated the adjustment for successful implementation of mitigation measures for CTR using the percentage of potentially realized takes for the PCT project (see table 6-20 in the POA's application). The data from PCT Phase 1 and PCT Phase 2 most accurately reflect the current marine mammal monitoring program, the current program's effectiveness, and

CIBW occurrence in the CTR project area. Between the 2 phases of the PCT project, 90 total Level B harassment takes were authorized and 53 were potentially realized, equating to an overall percentage of 59 percent. The SFD Project, during which only 7 percent of authorized take was potentially realized, represents installation of only 12 piles during a limited time period and does not represent the much higher number of piles and longer construction timeframe anticipated for the CTR project.

In the proposed rule (89 FR 85686, October 28, 2024), NMFS concurred that the 59-percent adjustment accurately accounted for the efficacy of the POA's marine mammal monitoring program and required shutdown protocols, based on past performance. Between the publication of the proposed rule and this final rule, POA submitted the final monitoring report for the NES1 project, and those data have been incorporated in this final rule. The sighting rates for CIBW at the POA shown in table 13 have been adjusted based on the new data. Additionally, the percentage of potentially realized takes from the NES1 project was higher than previous projects at 68 percent (49 out of 72 authorized takes). NMFS, therefore, has applied the highest previously observed take percentage as a conservative correction factor and assumes that approximately 68 percent of the takes calculated for CTR may actually be realized (table 18). Take by Level A harassment is not anticipated or authorized for CIBWs because the POA will be required to shut down activities when CIBWs approach and or enter the Level B harassment zone, which in all cases is larger than the estimated Level A harassment zones (see the Mitigation section for more information).

Table 18—Calculated Level B Harassment Takes of CIBWs by Month, Year, and Activity

1

Apr

May

Jun

Jul

Aug

2

Sep

2

Oct

2

Nov

Year 1

1

36-in vibratory installation

3

1.59

1.84

3.45

0.98

17.30

13.79

7.06

1.45

36-in vibratory removal

3

0.24

0.12

0.27

0.08

1.48

1.01

0.89

0.49

72-in vibratory installation (attenuated)

0.48

0.54

1.01

0.29

4.08

3.26

3.33

0.06

72-in vibratory installation (unattenuated)

4

0.06

0.03

0.05

0.01

0.24

0.20

0.21

0.06

72-in impact installation (attenuated)

2.35

3.36

7.11

1.97

31.93

24.48

24.02

3.62

72-in impact installation (unattenuated)

4

0.49

0.27

0.41

0.11

2.06

1.65

1.73

0.51

Year 1 total

173

With 68% Correction Factor

5

118

Year 2

1

36-in vibratory installation

3

1.91

1.54

2.87

0.82

14.42

11.49

5.88

1.45

36-in vibratory removal

3

0.24

0.12

0.27

0.08

1.48

1.01

0.89

0.00

72-in vibratory installation (attenuated)

0.48

0.44

0.81

0.23

4.08

2.87

2.94

0.42

72-in vibratory installation (unattenu

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