85686 Federal Register / Vol. 89, No. 208 / Monday, October 28, 2024 / Proposed Rules 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

50 CFR Part 217 

[Docket No. 241018–0276] 

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: Proposed rule; request for 

comments. 

SUMMARY: NMFS received a request from 

the Don Young Port of Alaska (POA) for 

authorization to take marine mammals 

incidental to the Cargo Terminals 

Replacement Project at the existing port 

facility in Anchorage, Alaska over the 

course of 5 construction seasons (2026 

through 2030). Pursuant to the Marine 

Mammal Protection Act (MMPA), NMFS 

is proposing regulations setting forth 

permissible methods of taking, other 

means of effecting the least practicable 

adverse impact on such marine mammal 

stocks (i.e., mitigation measures), and 

requirements pertaining to monitoring 

and reporting such takes and requests 

comments on the proposed regulations. 

NMFS will consider public comments 

prior to making any final decision on 

the promulgation of the requested 

MMPA regulations, and NMFS’s 

responses to public comments will be 

summarized in the final notification of 

our decision. 

DATES: Comments and information must 

be received no later than November 27, 

2024. 

ADDRESSES: A plain language summary 

of this proposed rule is available at 

https://www.regulations.gov/docket/ 

NOAA-NMFS-2024-0030. You may 

submit comments on this document, 

identified by NOAA–NMFS–2024–0030, 

by the following method: 

• Electronic Submission: Submit all 

electronic public comments via the 

Federal e-Rulemaking Portal. Visit 

https://www.regulations.gov and type 

NOAA–NMFS–2024–0030 in the Search 

box. Click on the ‘‘Comment’’ icon, 

complete the required fields, and enter 

or attach your comments. 

Instructions: Comments sent by any 

other method, to any other address or 

individual, or received after the end of 

the comment period, may not be 

considered by NMFS. All comments 

received are a part of the public record 

and will generally be posted for public 

viewing on https://www.regulations.gov 

without change. All personal identifying 

information (e.g., name, address, etc.), 

confidential business information, or 

otherwise sensitive information 

submitted voluntarily by the sender will 

be publicly accessible. NMFS will 

accept anonymous comments (enter ‘‘N/ 

A’’ in the required fields if you wish to 

remain anonymous). 

Electronic copies of the application 

and supporting documents, 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-portalaskas-construction-activities-portalaska-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 proposed regulations, 

promulgated under the authority of the 

MMPA (16 U.S.C. 1361 et seq.), would 

provide a framework for authorizing the 

take of marine mammals incidental to 

construction activities associated with 

the POA’s Modernization Program, 

including impact and vibratory pile 

driving. 

NMFS received an application from 

the POA requesting 5-year regulations 

and a letter of authorization issued 

thereunder to take individuals of seven 

species, comprising nine stocks of 

marine mammals by Level A harassment 

and Level B harassment incidental to 

the POA’s activities. No serious injury 

or mortality is anticipated or proposed 

for authorization. Please see Background 

below for definitions of harassment. 

Legal Authority for the Proposed Action 

Section 101(a)(5)(A) of the MMPA (16 

U.S.C. 1371(a)(5)(A)) directs the 

Secretary of Commerce 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 the 

discussion below in the Proposed 

Mitigation section), as well as 

monitoring and reporting requirements. 

Section 101(a)(5)(A) of the MMPA and 

the implementing regulations at 50 CFR 

part 216, subpart I provide the legal 

basis for issuing this proposed rule 

containing 5-year regulations and for 

any subsequent Letters of Authorization 

(LOAs). 

Summary of Major Provisions Within 

the Proposed Rule 

Following is a summary of the major 

provisions of this proposed rule 

regarding POA’s activities. These 

measures include: 

• Prescribing permissible methods of 

taking of small numbers of marine 

mammals by Level A harassment and/or 

Level B harassment incidental to the 

Cargo Terminals Replacement Project; 

• Required 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 beluga whales; 

• Establishment of shutdown zones 

equivalent to or greater than the 

estimated Level A harassment zones for 

other species; 

• Bubble curtains required 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 and for vibratory 

driving of all temporary (24-in (0.61 m) 

or 36-in (0.91 m)) and permanent (72-in) 

piles between August and October; 

• 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 

proposed regulations would 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 


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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 the permissible 

methods of taking and 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 

are set forth. The definitions of all 

applicable MMPA statutory terms cited 

above are included in the relevant 

sections below. 

National Environmental Policy Act 

To comply with the National 

Environmental Policy Act of 1969 

(NEPA; 42 U.S.C. 4321 et seq.) and 

NOAA Administrative Order (NAO) 

216–6A, NMFS must evaluate our 

proposed action’s (i.e., promulgation of 

regulations and subsequent issuance of 

a LOA thereunder) and alternatives to 

that action’s potential impacts on the 

human environment. 

Accordingly, NMFS has prepared an 

Environmental Assessment (EA) to 

evaluate the environmental impacts 

associated with the issuance of the 

proposed regulations and LOA. NMFS’ 

EA is available at https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-portalaskas-construction-activities-portalaska-modernization. We will review 

all comments submitted in response to 

this notice prior to concluding our 

NEPA process or making a final 

decision on this request. 

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: Cargo Terminals Replacement (CTR) 

at the POA in Anchorage, Alaska. NMFS 

provided comments on the application 

on March 3, 2023, 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, we 

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 one comment letter from the 

Center for Biological Diversity. NMFS 

has reviewed all submitted material and 

taken the information into consideration 

during the drafting of this proposed 

rule. 

The POA’s request is for take of seven 

species of marine mammals by Level B 

harassment and for a subset of these 

species, Level A harassment. Neither 

POA nor NMFS expect serious injury or 

mortality to result from the specified 

activities. If promulgated, the 

regulations would be effective for the 

first 5 construction seasons (2026– 

2030). 

NMFS previously issued IHAs to the 

POA for similar work (85 FR 19294, 

April 6, 2020; 86 FR 50057, September 

7, 2021; 89 FR 2832, January 14, 2024). 

The POA complied with all the 

requirements (e.g., mitigation, 

monitoring, and reporting) of the 

previous IHAs and information 

regarding their monitoring results may 

be found in the Effects of the Specified 

Activity on Marine Mammals and their 

Habitat and Estimated Take of Marine 

Mammals sections of this proposed rule 

and online at https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/incidentaltake-authorizations-constructionactivities. 

Description of the Specified Activities 

Overview 

The POA, located on Knik Arm in 

upper Cook Inlet, provides critical 

infrastructure for the citizens of 

Anchorage and a majority of the citizens 

of Alaska. The POA was constructed 

primarily in the 1960s and is currently 

in poor condition and substantially past 

its initial design life. The existing cargo 

terminals T1, T2, and T3 are 

deteriorating and in poor structural 

condition and present safety and 

security concerns for human health and 

the economic stability of the state of 

Alaska. The PAMP is designed to 

replace the existing facilities with new 

infrastructure incorporating modern 

seismic codes over a 75-year design life. 

PAMP Phase 2B includes the demolition 

and replacement of terminals T1 and T2 

and the partial demolition of T3. This 

phase is expected to take approximately 

6 years of in-water work to complete. If 

promulgated, the regulations would be 

effective for the first 5 construction 

seasons (2026–2030). 

In-water pile installation will include 

both temporary (24-in (0.61 m) 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) would 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. Inwater work associated with the project 

would include installation of 

approximately 275 permanent piles and 

450 temporary piles and vibratory 

extraction of approximately 46 

temporary piles over the 5-year period. 

Dates and Duration 

The POA anticipates that in-water 

construction activities associated with 

this proposed rule would begin on April 

1, 2026 and extend through November 

30, 2030. In-water pile installation and 

removal associated with the CTR project 

is anticipated to take place over 

approximately 689 hours on 

approximately 337 nonconsecutive days 

between the months of April and 

November over the 5 year period (see 

table 1 for estimated production rates 

and durations). While the exact 

sequence of demolition and 

construction is uncertain, an estimated 

schedule is shown in table 2. This 

schedule is based on best available 

information and is not intended to be a 

limitation on the number of pile 

installation or removal hours that may 

occur in any given month. 

The POA has presented the schedule 

shown in table 2 using the best available 

information derived from what is 

known of the existing Cargo Terminals 

site and the POA’s experience with 

similar construction and demolition 

projects. A typical construction season 

at the POA extends from approximately 

mid-April to mid-October (6 months) 

and may include November. Exact dates 

of ice-out in the spring and formation of 

new ice in the fall vary from year to year 

and cannot be predicted with accuracy. 

In-water pile installation and removal 

cannot occur during the winter months 

when ice is present because of the 

hazards associated with moving ice 

floes that change directions four times a 

day, preventing the use of tugs, barges, 

workboats, and other vessels. Ice 


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movement also prevents accurate 

placement of piles. 

While the POA plans to conduct as 

much work as possible between April 

and July, when there is lower Cook Inlet 

beluga whale (CIBW; Delphinapterus 

leucas) abundance (see the Description 

of Marine Mammals in the Area of 

Specified Activities section for details 

on CIBW presence at the POA), frontloading of work is dependent on 

construction sequencing. Construction 

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 not 

possible 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. Exact project sequencing 

and installation and extraction methods 

are at the discretion of the construction 

crew. Construction dates may change 

because of unexpected project delays, 

ongoing construction activities in other 

areas of the POA, timing of ice-out and 

spring breakup, and other factors. 

Therefore, the estimated schedule (table 

2) reflects a realistic scenario for the 

proposed project, but conditions on the 

ground may result in slight changes to 

this estimated schedule. 


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TABLE 1—PILE INSTALLATION AND

REMOVAL

METHODS, ESTIMATED

AMOUNTS, AND

ESTIMATED

DURATIONS FOR

YEARS 1–5 

Activity type Pile size and type 

Total 

estimated 

number of 

piles 

Estimated number 

of piles in the 

water 1

Average 

vibratory 

duration per pile 

(minutes) 

Average 

impact 

duration 

per pile 

(minutes) 

Estimated 

impact 

strikes per 

pile 

Total duration of 

removal or installation in water 

(hours) 

Average 

production 

rate, piles 

per day 

(range) 

Estimated 

number of 

days over 5 

years 

Temporary pile installation .................... 24- or 36-in (61- or 91-cm) Steel pipe 565 450 30 ................ .................... 225 hours 2–4 144. Temporary pile removal ........................ 24- or 36-in (61- or 91-cm) Steel pipe 161 46 45 ................ .................... 35 hours 2–4 15. Permanent pile installation .................... 72-in (182-cm) Steel pipe ..................... 310 275 10 86 5,743 440 hours 0.5–3 159. 

Total ............................................... ............................................................... 1,036 771 .............................. ................ .................... 700 hours .................... 337 days. 

Note: cm = centimeter(s); 1—Piles installed above the mean lower low water line are considered ‘‘in the dry’’ (i.e., not in-water). It is anticipated that the permanent and temporary piles in the three bents nearest the 

shore for all five trestles would be installed in the dry at low tide levels. An additional bent would be installed in the dry for the northernmost trestle of T1 and for the three trestles of T2. These piles are not considered to have the potential for impact to marine mammals and are thus excluded from the following analyses. 

TABLE 2—ESTIMATED

TIMING AND

DURATION (IN

HOURS PER

MONTH) OF

PILE INSTALLATION AND

REMOVAL

ACTIVITIES 1

Activity 

Duration (hours of activity by month and year) 

Apr May Jun Jul Aug Sep Oct Nov 

Imp 2 Vib 3 Imp Vib Imp Vip Imp Vib Imp Vib Imp Vib Imp Vib Imp Vib 

Year 1—2026 

24- or 36-in Temporary Pile Installation ............................. ............ 2.5 ............ 6.0 ............ 6.0 ............ 6.0 ............ 6.0 ............ 6.0 ............ 3.0 ............ 2 24- or 36-in Temporary Pile Removal ................................ ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 72-in Permanent Pile Installation 4 ...................................... 7.2 0.8 15.8 1.8 15.8 1.8 15.8 1.8 12.9 1.5 12.9 1.5 12.9 1.5 5.7 0.7 

Year 1 total hours ........................................................ 7.2 4.1 15.8 8.6 15.8 8.6 15.8 8.6 12.9 8.3 12.9 8.3 12.9 5.3 5.7 3.4 

Year 2—2027 

24- or 36-in Temporary Pile Installation ............................. ............ 3.0 ............ 5.0 ............ 5.0 ............ 5.0 ............ 5.0 ............ 5.0 ............ 2.5 ............ 2 24- or 36-in Temporary Pile Removal ................................ ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ ............72-in Permanent Pile Installation 4 ...................................... 7.2 0.8 12.9 1.5 12.9 1.5 12.9 1.5 12.9 1.5 11.5 1.3 11.5 1.3 5.7 0.7 

Year 2 total hours ........................................................ 7.2 4.6 12.9 7.3 12.9 7.3 12.9 7.3 12.9 7.3 11.5 7.1 11.5 4.6 5.7 2.7 

Year 3—2028 

24- or 36-in Temporary Pile Installation ............................. ............ 6.5 ............ 13.0 ............ 13.0 ............ 13.0 ............ 13.0 ............ 13.0 ............ 6.5 ............ 2 24- or 36-in Temporary Pile Removal ................................ ............ 0.8 ............ 2.3 ............ 2.3 ............ 2.3 ............ 1.5 ............ 1.5 ............ 0.8 ............ 0.8 72-in Permanent Pile Installation 4 ...................................... 5.7 0.7 5.7 0.7 5.7 0.7 4.3 0.5 4.3 0.5 4.3 0.5 4.3 0.5 4.3 0.5 

Year 3 total hours ........................................................ 5.7 7.9 5.7 15.9 5.7 15.9 4.3 15.8 4.3 15.0 4.3 15.0 4.3 7.8 4.3 3.3 

Year 4—2029 

24- or 36-in Temporary Pile Installation ............................. ............ 2.5 ............ 5.5 ............ 5.5 ............ 6.0 ............ 5.5 ............ 5.5 ............ 2.5 ............ 2 24- or 36-in Temporary Pile Removal ................................ ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 ............ ............72-in Permanent Pile Installation 4 ...................................... 7.2 0.8 12.9 1.5 12.9 1.5 12.9 1.5 12.9 1.5 11.5 1.3 11.5 1.3 5.7 0.7 

Year 4 total hours ........................................................ 7.2 4.1 12.9 7.8 12.9 7.8 12.9 8.3 12.9 7.8 11.5 7.6 11.5 4.6 5.7 2.7 

Year 5—2030 

24- or 36-in Temporary Pile Installation ............................. ............ 2.5 ............ 6.0 ............ 6.0 ............ 6.0 ............ 6.0 ............ 5.5 ............ 5.5 ............ 2.5 24- or 36-in Temporary Pile Removal ................................ ............ 0.8 ............ 0.8 ............ 1.5 ............ 1.5 ............ 0.8 ............ 0.8 ............ 0.8 ............ 0.8 72-in Permanent Pile Installation 4 ...................................... 4.3 0.5 12.9 1.5 12.9 1.5 12.9 1.5 11.5 1.3 11.5 1.3 11.5 1.3 4.3 0.5 Year 5 total hours ............................................................... 4.3 3.8 12.9 8.3 12.9 8.3 12.9 8.3 11.5 8.1 11.5 7.6 11.5 7.6 4.3 3.8 

1 Duration estimates assume a single hammer active at any time and therefore likely overestimates of actual time needed due to simultaneous pile installation and removal; 2 Impact pile installation; 


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-f--
85690 Federal Register / Vol. 89, No. 208 / Monday, October 28, 2024 / Proposed Rules 

3Vibratory pile installation or extraction; 4To account for piles driven in water less than 3m 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. Numbers may not add exactly due to rounding. 


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Specific Geographic Region 

The specific geographic region for this 

action 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 (figure 1). 

Northern Cook Inlet bifurcates into 

Knik Arm to the north and Turnagain 

Arm to the east. Knik Arm is generally 

considered to begin at Point Woronzof, 

7.4 km southwest of the POA. From 

Point Woronzof, Knik Arm extends 

about 48 km in a north-northeasterly 

direction to the mouths of the 

Matanuska and Knik rivers. At Cairn 

Point, just northeast of the POA, Knik 

Arm narrows to about 2.4 km before 

widening to as much as 8 km at the tidal 

flats northwest of Eagle Bay at the 

mouth of Eagle River. 

Knik Arm comprises narrow channels 

flanked by large tidal flats composed of 

sand, mud, or gravel, depending upon 

location. Approximately 60 percent of 

Knik Arm is exposed at Mean Lower 

Low Water (MLLW). The intertidal 

(tidally influenced) areas of Knik Arm 

are mudflats, both vegetated and 

unvegetated, which consist primarily of 

fine, silt-sized glacial flour. Freshwater 

sources often are glacially born waters, 

which carry high suspended sediment 

loads as well as a variety of metals such 

as zinc, barium, mercury, and cadmium. 

Surface waters in Cook Inlet typically 

carry high silt and sediment loads, 

particularly during summer, making 

Knik Arm an extremely silty, turbid 

waterbody with low visibility through 

the water column. The Matanuska and 

Knik Rivers contribute the majority of 

freshwater and suspended sediment into 

Knik Arm during summer. Smaller 

rivers and creeks also enter along the 

sides of Knik Arm (U.S. Department of 

Transportation and Port of Anchorage, 

2008). During winter, sea, beach, and 

river ice are dominant physical forces 

within Cook Inlet and Knik Arm. In 

upper Cook Inlet, sea ice generally 

forms in October to November and 

continues to develop through February 

or March (Moore et al., 2000). 

Tides in Cook Inlet are semidiurnal, 

with two unequal high and low tides 

per tidal day (tidal day = 24 hours, 50 

minutes). Due to Knik Arm’s 

predominantly shallow depths and 

narrow widths, tides near Anchorage are 

greater than those in the main body of 

Cook Inlet. The tides at the POA have 

a mean range of about 8 m, and the 

maximum water level has been 

measured at more than 12.5 m at the 

Anchorage station (NMFS, 2015). 

Currents throughout Cook Inlet are 

strong and tidally periodic, with average 

velocities ranging from 3 to 6 knots (5.6 

to 11.1 kilometers (km)/hour (h)) 

(Sharma and Burrell, 1970). Maximum 

current speeds in Knik Arm, observed 

during spring ebb tide, exceed 7 knots 

(13 km/h). These tides result in strong 

currents in alternating directions 

through Knik Arm and a well-mixed 

water column. The navigation harbor at 

the POA is a dredged basin in the 

natural tidal flat. Sediment loads in 

upper Cook Inlet can be high; spring 

thaws occur, and accompanying river 

discharges introduce considerable 

amounts of sediment into the system 

(Ebersole and Raad, 2004). Natural 

sedimentation processes act to 

continuously infill the dredged basin 

each spring and summer. 

The Municipality of Anchorage is 

located in the lower reaches of Knik 

Arm of upper Cook Inlet (see figure 2– 

1 in the POA’s application). The POA 

sits on the industrial waterfront of 

Anchorage, just south of Cairn Point and 

north of Ship Creek (lat. 61°15′ N, long. 

149°52′ W; Seward Meridian) (figure 1). 

The POA’s boundaries currently occupy 

an area of approximately 0.52 km2

(figure 2). Other commercial and 

industrial activities related to secured 

maritime operations are located near the 

POA on Alaska Railroad Corporation 

property immediately south of the POA, 

on approximately 0.45 km2 at a similar 

elevation. The POA is located north of 

Ship Creek, an area that experiences 

concentrated marine mammal activity 

during seasonal runs of several salmon 

species. Ship Creek serves as an 

important recreational fishing resource 

and is stocked twice each summer. Ship 

Creek flows into Knik Arm through the 

Municipality of Anchorage industrial 

area. Joint Base Elmendorf-Richardson 

(JBER) is located east of the POA, 

approximately 30.5 m higher in 

elevation. The U.S. Army Defense Fuel 

Support Point-Anchorage site is located 

east of the POA, south of JBER, and 

north of Alaska Railroad Corporation 

property. The perpendicular distance to 

the west bank directly across Knik Arm 

from the POA is approximately 4.2 km. 

The distance from the POA (east side) 

to nearby Port MacKenzie (west side) is 

approximately 4.9 km. 

BILLING CODE 3510–22–P 


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Figure 1 - Overview of POA Location in Knik Arm 

-•.•• -~-•-CaigoT8f1rim•hi 

t::!=:t~~~: -. 

r 

J) 
Federal Register / Vol. 89, No. 208 / Monday, October 28, 2024 / Proposed Rules 85693 

BILLING CODE 3510–22–C 

Detailed Description of the Specified 

Activities 

As discussed previously, marine-side 

infrastructure and facilities at the POA 

are in need of replacement because they 

are substantially past their design life 

and in poor and deteriorating structural 

condition. Those facilities include three 

general cargo terminals, two petroleum 

terminals, a dry barge landing, and an 

upland sheet-pile-supported storage and 

work area. To address deficiencies, the 

POA is modernizing its marine 

terminals through the PAMP to enable 

safe, reliable, and cost-effective Port 

operations. The PAMP will support 

infrastructure resilience in the event of 


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Port of Alaska Modernization 

Program Phasei;; 

- Pllase1 

- Phase2A 

Phase 2B 

- Phases 3. 4. & 5 

Figure 2 - Overview of Cargo Terminals Location at POA 
85694 Federal Register / Vol. 89, No. 208 / Monday, October 28, 2024 / Proposed Rules 

a catastrophic natural disaster over a 75- 

year design life. 

The PAMP is critical to maintaining 

food and fuel security for the state. At 

the completion of the PAMP, the POA 

will have modern, safe, resilient, and 

efficient facilities through which more 

than 90 percent of Alaskans will 

continue to obtain food, supplies, tools, 

vehicles, and fuel. The PAMP is divided 

into five separate phases; these phases 

are designed to include projects that 

have independent utility yet streamline 

agency permitting. The projects 

associated with the PAMP include: 

• Phase 1: Petroleum and Cement 

Terminal (PCT Phase 1 and 2) and 

South Floating Dock (SFD) replacement; 

• Phase 2A: North Extension 

Stabilization Phase 1 (NES1); 

• Phase 2B: CTR; 

• Phase 3: Petroleum, Oil and 

Lubricants Terminal 2 Replacement; 

• Phase 4: North Extension 

Stabilization part 2; and 

• Phase 5: Demolition of Terminal 3. 

Phase 1 of the PAMP was completed 

in 2022. NMFS issued IHAs for take 

incidental to the now completed PCT 

(Phase 1 and Phase 2; 85 FR 19294, 

April 6, 2020) and SFD projects (86 FR 

50057, September 7, 2021). Phase 2A of 

the PAMP began in 2023; an IHA was 

issued for phase one of the NES project 

(89 FR 2832, January 14, 2024) and inwater construction associated with this 

project is planned for 2024. The project 

discussed herein, CTR, is Phase 2B of 

the PAMP and is proposed to begin 

onshore preparation in 2025 and inwater construction work in 2026. 

The purpose of the CTR project is to 

replace the existing general cargo docks. 

It would address deteriorating 

conditions of the existing cargo 

facilities; improve operational safety 

and efficiency; accommodate modern 

(existing and future) shipping 

operations; and improve the resiliency 

of the POA to extreme seismic events, 

all while sustaining ongoing cargo 

operations. This project is urgently 

needed due to severe corrosion of the 

foundation piles and deteriorating 

structural conditions at Terminals 1, 2, 

and 3. The existing terminals are more 

than 50 years old and suffer from severe 

damage to the foundation piles caused 

by corrosion and seismic forces. The 

piles have exceeded their useful service 

life, and multiple engineering 

investigations have highlighted the 

probability of wharf and trestle structure 

failure during a future major seismic 

event. The remaining service life of the 

cargo terminals is unknown. These 

facilities must be replaced with new 

resilient terminals for the Port to 

continue to meet its critical role serving 

Alaska’s general cargo needs as well as 

supporting national defense and 

military readiness capabilities. 

The geographical isolation of Alaska 

and the POA’s role as the containerized 

logistic hub and distribution center for 

much of the state make the cargo 

terminals a critical lifeline for the 

southcentral region and Alaska. There 

are no other ports with the cargo 

capacity, proximity to Alaska’s 

population centers, and intermodal 

transportation capabilities that can 

support the logistic missions sustained 

by the POA, including commerce, 

national defense, and earthquake 

resiliency/disaster response and 

recovery. 

CTR Project Activities 

The CTR project includes 

construction of new terminals T1 and 

T2, which include planned wharves and 

access trestles. The two new terminals 

would be located 140 feet (ft) (42.7 

meters (m)) seaward of the existing T1, 

T2, and T3. It is anticipated that this 

more seaward location of the new 

terminals will reduce sedimentation, 

improve room for handling of berthing 

ships, and allow construction of the 

new terminals while the existing 

terminals remain in use. CTR also 

includes demolition of the existing 

Petroleum, Oil, and Lubricants Terminal 

1 (POL1) and general cargo terminals 

(T1, T2, and T3). 

The southernmost end of the new T1 

and T2 would be approximately 1.4 km 

(0.9 mile (mi)) north of Ship Creek. 

Construction of the Project will include 

completion of the following 

components: 

• Component 1. Onshore ground 

improvement shoreline stabilization 

(2025) 

• Component 2. Shoreline expansion 

and protection (2026) 

• Component 3. General cargo 

terminals (new Terminals 1 and 2) 

construction (2026–2031) 

• Component 4. Demolition of 

existing terminals (POL1 and general 

cargo terminals (existing Terminals 1, 2, 

and 3)) (2026–2031) 

• Component 5. Onshore utilities and 

storm drain outfall replacement (2030– 

2031) 

Of these activities, only Components 

3 and 4 include construction work that 

would occur in the water, and therefore, 

these would be the only components of 

the project expected to potentially 

impact marine mammals. 

Landside Activities 

Landside activities include work 

which takes place ‘‘in the dry,’’ either 

above the high tide line or in the 

intertidal zone but de-watered. These 

activities include shoreline stabilization 

and protection as well as placement of 

onshore utilities and decking 

components. 

Ground Improvement Shoreline 

Stabilization—A ground improvement 

technique, such as deep soil mixing 

(DSM), or a similar technique would be 

used to stabilize the shoreline. DSM and 

similar techniques mechanically mix 

weak soils with a cement binder causing 

the soils to behave more like soft rock. 

This process is used to create 

foundations for buildings and roads and 

is used in earthquake-prone areas to 

prevent soil liquefaction. Soil 

improvements at trestle abutments, and 

potentially between the abutments, will 

mitigate the potential for seismicinduced slope failure that could result 

in catastrophic structural failure. 

The first stage of construction would 

include installation of soil 

improvements in the five locations 

where the access trestles meet the beach 

to provide geotechnical stability to the 

embankment. Centered at each of the 

five trestle abutments, the ground 

improvement technique would create 

approximately 200- by 96-ft (61- by 29- 

m) blocks of treated soil extending from 

the surface to the top of the clay layer 

approximately 85-ft (25.9-m) deep (see 

figure 1–2 of the POA’s application). 

The size of the block is designed to 

create enough contact area with the clay 

layer to restrain and significantly reduce 

the overall ground movements of the 

liquefiable soils surrounding the trestle 

abutment. If deemed necessary for 

geotechnical stability, ground 

improvements would extend along the 

embankment in areas between the 

abutments. 

During construction, a temporary soil 

work pad would be constructed at each 

of the five trestles to provide a level 

temporary work surface. The ground 

improvement panels/columns would 

extend approximately 100 feet (ft) (30.5- 

m) seaward and shoreward of the crest 

of the slope and approximately 30 ft (9- 

m) to either side of the trestle structure. 

Temporary armoring will protect the 

work pad from water forces while in 

use. After completion of the ground 

improvement work, the temporary 

construction work pads will be removed 

and the foreshore graded and armored. 

Shoreline Expansion and Protection— 

The existing shoreline behind the 

existing Terminals 1, 2, and 3 is 

irregular, with two areas where the 

shoreline is located about 100 ft (30-m) 

to the east of the typical shoreline (see 

figure 1–3 of the POA’s application). 

These areas would be excavated to 

remove deposited silts before the areas 


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are then filled with more dense, stable 

materials such as clean gravel and rock. 

The filled area would provide a 

consistent shoreline and additional 

container storage area. 

Excavation for the CTR project would 

be limited to removal of materials that 

are above the high-water line or below 

the high-water line in a dewatered state. 

Sea-based dredging of materials under 

water will not take place as part of this 

project. 

After ground improvement work and 

shoreline expansion have been 

completed, the slope along the shore 

would be secured with armor stone 

placed over the clean gravel and rock 

fill. Placement of armor rock requires 

good visibility of the shore as each rock 

is placed carefully to interlock with 

surrounding armor rock. It is therefore 

anticipated that placement of most 

armor rock, filter rock, and granular fill 

will occur in the dry at low tide levels; 

however, some placement of armor rock, 

filter rock, and granular fill may occur 

in shallow water (i.e., less than 3 m 

deep). After placement of armor rock, 

the top of the fill will be paved to match 

the existing backland pavements. 

Onshore utilities and storm drain 

outfall replacement—The replacement 

of onshore utilities will involve 

construction on land and replacement of 

utilities above the high tide line, on 

land. Similarly, the storm drain outfall 

replacement will involve construction 

on land and replacement of four outfall 

pipes above the high tide line. No inwater work is proposed as a part of this 

component. 

Ground improvement shoreline 

stabilization, shoreline expansion and 

protection, and onshore utilities and 

storm drain outfall replacement 

activities would take place on land or in 

the dry. While a minimal amount of fill 

and armor rock placement may occur in 

water, this activity would not be 

expected to impact marine mammals. 

Therefore, take of marine mammals 

related to these activities is not 

anticipated or proposed to be 

authorized, and it will not be 

considered further in this proposed 

rulemaking. 

In-Water Construction 

New terminals T1 and T2 would be 

constructed as seismically resilient 

adjoining terminals on a continuous 

berthline with mooring features and 

appurtenances as required to support 

safe ship mooring for lift-on/lift-off and 

roll-on/roll-off related cargo handling 

operations. The new T1 wharf would be 

870 ft x 120 ft (265- x 37-m) with two 

36-ft-wide (11-m) trestles of varying 

length. The new T2 wharf would be 932 

ft x 120 ft (284- x 37-m) with two 259- 

ft- long x 54-ft-wide (79- x 16.5-m) 

trestles and one 259-ft-long x 76-ft-wide 

(79- x 23-m) trestle. Both T1 and T2 

would be constructed using 48- and 72- 

in-diameter (121- and 183-centimeter 

(cm), respectively) steel piles. The 48- 

in-diameter piles will be installed in the 

dry. 

Both new terminals would be 

designed to accommodate lift-on/lift-off 

container operations serviced by railmounted ship-to-shore cranes. 

Structural, in-deck, and surface features 

to support operational interface for three 

100-gauge rail mounted gantry cranes, 

and associated appurtenances along 

with an on-terminal combination 

stevedore-operations building, would be 

included on the wharf. Additionally, T2 

would be designed to support roll-on/ 

roll-off container operations and other 

multi-purpose cargo functions. The 

reinforced concrete deck structure for 

both new terminals and all new access 

trestles would be designed to 1,000 

pound per square foot load capacity. 

Construction would also include 

installation of power, lighting, 

communications, and signal 

infrastructure to terminal and onshore 

electrically powered features; potable 

water service including ship’s water; 

and fire-flow water for terminal-related 

operations. The on-terminal stevedoreoperations building would also be 

constructed with a connection to the 

onshore, existing public utility 

infrastructure. 

In addition to these permanent 

structures, temporary work including 

temporary pile installation and removal 

would be required to support 

construction. Temporary piles would 

likely be 36-in-diameter (91-cm) steel; 

however, 24-in (61-cm) steel piles may 

be used in place of some of the larger 

temporary piles. Various work boats and 

barges would be utilized and would be 

moored at or in the immediate vicinity 

of the project, but these vessels are not 

expected to increase overall noise levels 

at the POA above existing operational 

levels. No thrusters or other dynamic 

positioning methods will be used during 

pile driving activities. 

Construction of each terminal would 

require installation and removal of 

temporary steel pipe piles, including 

template piles, and installation of 

permanent steel pipe piles. Pile 

installation would occur in water 

depths that range from a few feet or dry 

(dewatered) conditions nearest the shore 

to approximately 20 meters (70 ft) at the 

outer face of the wharves, depending on 

tidal stage; the mean diurnal tide range 

at the POA is approximately 8.0 meters 

(26 ft; NOAA 2015). 

Concurrent Activities—In-water 

construction activities would occur at 

multiple locations across the project site 

simultaneously; the POA anticipates 

that two ‘‘spreads’’ (a construction crew 

with crane and pile driving hammer) 

would be on site and working 

throughout the construction season, 

with a third ‘‘spread’’ present on some 

days. Of the two regular spreads, one 

would be designated for permanent (72- 

in) piles and one for temporary (24-in or 

36-in) piles. Each spread would operate 

a single hammer at a time (impact or 

vibratory), with no more than two 

vibratory hammers simultaneously 

active in-water at any given time. It is 

not expected that three piles would be 

driven concurrently, and this scenario is 

not addressed further in this analysis. 

The only combinations of vibratory 

hammers that could be used 

simultaneously would be for installation 

of an attenuated (through use of a 

bubble curtain; see Proposed Mitigation 

later in this notice) 72-in pile and an 

attenuated temporary pile, an attenuated 

72-in pile and an unattenuated 

temporary pile, or two temporary piles. 

There would be no simultaneous 

driving of unattenuated 72-in piles in 

water. Simultaneous use of two 

hammers would increase production 

rates. 

Duration of active hammer use is 

anticipated to be brief each day (see 

table 1), and it is, therefore, anticipated 

that overlap in use of hammers would 

be uncommon. Pile installation and 

removal would occur intermittently 

over the work period, for durations of 

minutes to hours at a time. Use of two 

simultaneous hammers would serve to 

reduce the overall duration of in-water 

pile installation and removal during 

each construction season. One 

construction crane would likely be 

based on a floating work barge, and one 

would likely be based on land or on an 

access trestle. Table 3 provides a 

summary of concurrent pile driving 

scenarios. 


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TABLE 3—POTENTIAL CONCURRENT DRIVING SCENARIOS THAT COULD OCCUR DURING CTR CONSTRUCTION

Equipment type and quantity Pile type and size Construction months 

Vibratory × 2 .................................... 2 x 36-in steel pipe 1 ............................................................................. April–July. 

Vibratory, Impact .............................. 2 x 72-in steel pipe 2 OR 1 x 72-in steel pipe 2 (impact) and 

1 x 36-in steel pipe (vibratory) 

April–November. 

1POA 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; 2All 72-in piles driven concurrently will be attenuated. 

Pile Installation and Removal— 

Vibratory and impact hammers would 

be used for the installation of 72-in 

(182-cm) permanent piles. Vibratory 

hammers would be used for installation 

and removal of 24- (61-cm) and or 36- 

in (91-cm) temporary piles; however, if 

obstructions are encountered during 

installation, impact driving may be 

necessary. Installation and removal of 

piles in the dry would be maximized as 

much as feasible, depending on 

construction sequencing and tide 

heights. However, the exact number of 

piles that may be installed and removed 

in the dry is unknown (see table 1 for 

estimates and numbers of piles analyzed 

for in-water construction activities). 

Impact and vibratory pile driving 

activities conducted in the dry are not 

expected to impact marine mammals 

and therefore, are not discussed further 

in this rule. 

Pile Cutting—A majority of in-water 

temporary piles (approximately 90 

percent) would be cut off at the mudline 

and remain in place, removed via direct 

pulling, or would remain in place intact 

(without cutting). Temporary piles that 

conflict with construction or operations 

or that can be removed in the dry would 

be removed. Leaving piles in place 

below the mudline supports stability of 

the soil. Also, many of the existing T1 

and T2 piles are corroded and may 

break during removal, with the lower 

part remaining in place. The existing 

structure is closer to shore than new 

construction, and many piles can be cut 

or removed in the dry when their 

location is dewatered. 

The number of piles that would be cut 

or remain in place would be maximized 

as feasible; however, the exact number 

of piles that may be cut or can remain 

in place is unknown (see table 1 for best 

estimates of piles to be removed). While 

the exact method of pile cutting is at the 

discretion of the construction 

contractor, any methodology considered 

for cutting and removing the piles 

would account for worker safety, 

constructability, and minimization of 

potential acoustic impacts that the 

operation may have on marine 

mammals. Potential methods of 

underwater cutting include ultrathermic 

cutting, pile clippers or wire-saws. 

Underwater ultrathermic cutting is 

performed by commercial divers using 

hand-held equipment to cut or melt 

through ferrous and non-ferrous metals. 

These systems operate through a torchlike process, initiated by applying a 

melting amperage to a steel tube packed 

with alloy steel rods, sometimes mixed 

with aluminum rods to increase the heat 

output. In the hands of skilled 

commercial divers, underwater 

ultrathermic cutting is reputed to be 

relatively fast and efficient, cutting 

through approximately 2 to 4 inches (5 

to 10 cm) per minute, depending upon 

the number of divers deployed. This 

efficacy may be constrained by the 

requirement to secure the severed piles 

from falling into the inlet to prevent an 

extreme hazard to the diver cutting the 

piles. Tidally driven currents in Cook 

Inlet may limit dive times to 

approximately 2 to 3 hours per highand low-tide event, depending upon the 

tide cycle and the ability of divers to 

efficiently perform the cutting task 

while holding position during high 

current periods. This activity is not 

considered to produce sound. 

Pile clipping and underwater sawing 

generate noise that is typically nonimpulsive, low-level, and short duration 

(typically less than 15 seconds per pile) 

(NAVFAC SW, 2020). Potential pile 

cutting methodologies are not 

anticipated to result in incidental take 

of marine mammals because they are 

either above water, do not last for 

sufficient duration to present the 

reasonable potential for disruption of 

behavioral patterns, do not produce 

sound levels likely to result in marine 

mammal harassment, or some 

combination of the above. Impacts on 

marine mammals from pile cutting are 

therefore considered de minimis and 

NMFS is not proposing to authorize 

incidental take from this activity. 

Demolition of Existing Terminals— 

Once the new T1, T2, and petroleum 

products transfer system are complete 

and operational, any remaining existing 

T1, T2, and POL1 platforms, wharves, 

and trestles would be dismantled (see 

figure 1–5 of the POA’s application). 

Existing and most temporary piles 

would be cut and removed, removed via 

vibratory extraction or direct pull, or left 

in place. The selection of construction 

equipment by the contractor, including 

cranes and barges, would determine the 

plans and sequencing for demolition. 

Portions of the existing terminals may 

be used for construction phasing and as 

support platforms for ongoing new 

construction, as feasible. 

T3 may be partially demolished 

during Phase 2B construction of T1 and 

T2, especially where the existing 

infrastructure may interfere with new 

construction. Elements of T3 that 

remain after Phase 2B is complete 

would remain in place until Phase 5, 

when they would be removed at that 

time. 

Demolition would take place above 

the water, and demolished decking, 

pipes, and other superstructure 

materials would be contained before 

they fall into the water following best 

management practices. Demolished 

materials would be removed by barge or 

truck. Because work would take place 

out of water with best management 

practices in place to limit any release of 

material into Cook Inlet, in addition to 

cutting off or leaving existing piles in 

place, impacts on marine mammals 

from demolition of the existing 

terminals are considered de minimis 

and NMFS is not proposing to authorize 

incidental take from this activity. 

Proposed mitigation, monitoring, and 

reporting measures are described in 

detail later in this document (please see 

Proposed Mitigation and Proposed 

Monitoring and Reporting). 

Description of Marine Mammals in the 

Specified Geographical Region 

There are seven species, comprising 9 

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 


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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; 

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 (https://

www.fisheries.noaa.gov/find-species). 

Table 4 lists all species or stocks for 

which take is likely and proposed to be 

authorized for the specified activities 

and summarizes information related to 

the population or stock, including 

regulatory status under the MMPA and 

Endangered Species Act (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 4 

are the most recent available at the time 

of publication (including from the draft 

2023 SARs) and are available online at: 

https://www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

marine-mammal-stock-assessmentreports. The most recent abundance 

estimate for CIBWs is available from 

Goetz et al. (2023) and available online 

at https://www.fisheries.noaa.gov/ 

feature-story/new-abundance-estimateendangered-cook-inlet-beluga-whales. 

TABLE 4—SPECIES LIKELY IMPACTED BY THE SPECIFIED ACTIVITIES

Common name Scientific name MMPA stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 1

Stock abundance 

Nbest, (CV, Nmin, 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) .... UND 5 0.57 

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, 290, 2022) 4 0.53 0 

Family Phocoenidae (porpoises): 

Harbor porpoise ............... Phocoena phocoena .............. Gulf of Alaska ......................... -/-; Y 31,046 (0.214, N/A, 

1998).

UND 5 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 

1Endangered 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.). 3These 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. 4This abundance estimate is from Goetz et al. (2023); which was published after the most recent CIBW SAR (Young et al., 2023). 5 UND means undetermined. 


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85698 Federal Register / Vol. 89, No. 208 / Monday, October 28, 2024 / Proposed Rules 

As indicated above, all seven species 

(nine managed stocks) in table 4 

temporally and spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur. Minke 

whales (Balaenoptera acutorostrata) and 

Dall’s porpoises (Phocoenoides dalli) 

also occur in Cook Inlet; however, the 

spatial occurrence of these species is 

such that take is not likely to occur, and 

they are not discussed further beyond 

the explanation provided here. Data 

from the Alaska Marine Mammal 

Stranding Network database (NMFS, 

unpublished data) provide additional 

support for these determinations. From 

2011 to 2020, only one minke whale and 

one Dall’s porpoise were documented as 

stranded in the portion of Cook Inlet 

north of Point Possession. Both were 

dead upon discovery; it is unknown if 

they were alive upon their entry into 

upper Cook Inlet or drifted into the area 

with the tides. With very few 

exceptions, minke whales and Dall’s 

porpoises do not occur in upper Cook 

Inlet, and therefore, take of these species 

is considered unlikely. 

In addition to what is included in 

sections 3 and 4 of the POA’s 

application (https://www.fisheries.

noaa.gov/action/incidental-takeauthorization-port-alaskas-constructionactivities-port-alaska-modernization), 

the SARs (https://www.fisheries.

noaa.gov/national/marine-mammalprotection/marine-mammal-stockassessments), and NMFS’ website, we 

provide further detail below informing 

the baseline for species likely to be 

found in the project area (e.g., 

information regarding current UMEs 

and known important habitat areas, 

such as Biologically Important Areas 

(BIAs; https://oceannoise.noaa.gov/ 

biologically-important-areas) (Van Parijs 

et al., 2015)). 

Gray Whale 

Gray whales are infrequent visitors to 

Cook Inlet but can be seasonally present 

during spring and fall in the lower inlet 

(Bureau of Ocean Energy Management 

(BOEM), 2021). Migrating gray whales 

pass through the lower inlet during their 

spring and fall migrations to and from 

their primary summer feeding areas in 

the Bering, Chukchi, and Beaufort seas 

(Swartz, 2018; Silber et al., 2021; 

BOEM, 2021). There are no BIAs for 

gray whales in Cook Inlet. 

Gray whales are rarely documented in 

upper Cook Inlet and in the project area. 

Gray whales were not documented 

during POA construction or scientific 

monitoring from 2005 to 2011 or during 

2016 (Prevel-Ramos et al., 2006; 

Markowitz and McGuire, 2007; Cornick 

and Saxon-Kendall, 2008, 2009; Cornick 

et al., 2010, 2011; Integrated Concepts 

and Research Corporation (ICRC), 2009, 

2010, 2011, 2012; Cornick and Pinney, 

2011; Cornick and Seagars, 2016); 

however, one gray whale was observed 

near Port MacKenzie during 2020 PCT 

construction (61 North (61N) 

Environmental, 2021) and a second 

whale was observed off of Ship Creek 

during 2021 PCT construction 

monitoring (61N Environmental, 2022a, 

Easley-Appleyard and Leonard, 2022). 

The whale observed in 2020 is believed 

to be the same whale that later stranded 

in the Twentymile River, at the eastern 

end of Turnagain Arm, approximately 

80 km southeast of Knik Arm. There 

was no indication that work at the PCT 

had any effect on the animal, which was 

reported to be in ‘‘fair to poor’’ 

condition during evaluation (see https:// 

www.fisheries.noaa.gov/feature-story/ 

alaska-gray-whale-ume-updatetwentymile-river-whale-likely-onetwelve-dead-gray-whales for more 

information). No gray whales were 

observed during POA’s transitional 

dredging or SFD construction 

monitoring from May to August, 2022 

(61N Environmental, 2022b, 2022c). 

Under the MMPA, a UME is defined 

as ‘‘a stranding that is unexpected; 

involves a significant die-off of any 

marine mammal population; and 

demands immediate response’’ (16 

U.S.C. 1421h(6)). A recently closed 

UME for gray whales along the West 

Coast and in Alaska occurred from 

December 17, 2018 through November 

9, 2023. During that time, 146 gray 

whales stranded off the coast of Alaska. 

The investigative team concluded that 

the preliminary cause of the UME was 

localized ecosystem changes in the 

whale’s Subarctic and Arctic feeding 

areas that led to changes in food, 

malnutrition, decreased birth rates, and 

increased mortality (see https://

www.fisheries.noaa.gov/national/ 

marine-life-distress/2019-2023-graywhale-unusual-mortality-event-alongwest-coast-and for more information). 

Given the changing environment in the 

polar regions due to climate change, 

there is potential for changes to gray 

whale behavior and distribution in the 

near future. 

Humpback Whale 

The 2022 Alaska and Pacific SARs 

described a revised stock structure for 

humpback whales, which modifies the 

previous stocks designated under the 

MMPA to align more closely with the 

ESA-designated distinct population 

segments (DPSs) (Carretta et al., 2023; 

Young et al., 2023). Specifically, the 

three previous North Pacific humpback 

whale stocks (Central and Western 

North Pacific stocks and a CA/OR/WA 

stock) were replaced by five stocks, 

largely corresponding with the ESAdesignated DPSs. These include 

Western North Pacific and Hawaii 

stocks and a Central America/Southern 

Mexico-CA/OR/WA stock (which 

corresponds with the Central America 

DPS). The remaining two stocks, 

corresponding with the Mexico DPS, are 

the Mainland Mexico-CA/OR/WA and 

Mexico-North Pacific stocks (Carretta et 

al., 2023; Young et al., 2023). The 

former stock is expected to occur along 

the west coast from California to 

southern British Columbia, while the 

latter stock may occur across the Pacific, 

from northern British Columbia through 

the Gulf of Alaska and Aleutian Islands/ 

Bering Sea region to Russia. 

The Hawaii stock consists of one 

demographically independent 

population (DIP) (Hawaii—Southeast 

Alaska/Northern British Columbia DIP) 

and the Hawaii—North Pacific unit, 

which may or may not be composed of 

multiple DIPs (Wade et al., 2021). The 

DIP and unit are managed as a single 

stock at this time, due to the lack of data 

available to separately assess them and 

lack of compelling conservation benefit 

to managing them separately (NMFS, 

2019, 2022b, 2023). The DIP is 

delineated based on two strong lines of 

evidence: genetics and movement data 

(Wade et al., 2021). Whales in the 

Hawaii—Southeast Alaska/Northern 

British Columbia DIP winter off Hawaii 

and largely summer in Southeast Alaska 

and Northern British Columbia (Wade et 

al., 2021). The group of whales that 

migrate from Russia, western Alaska 

(Bering Sea and Aleutian Islands), and 

central Alaska (Gulf of Alaska excluding 

Southeast Alaska) to Hawaii have been 

delineated as the Hawaii-North Pacific 

unit (Wade et al., 2021). There are a 

small number of whales that migrate 

between Hawaii and southern British 

Columbia/Washington, but current data 

and analyses do not provide a clear 

understanding of which unit these 

whales belong to (Wade et al., 2021; 

Carretta et al., 2023; Young et al., 2023). 

The Mexico-North Pacific stock is 

likely composed of multiple DIPs, based 

on movement data (Martien et al., 2021; 

Wade, 2021; Wade et al., 2021). 

However, because currently available 

data and analyses are not sufficient to 

delineate or assess DIPs within the unit, 

it was designated as a single stock 

(NMFS, 2019, 2022c, 2023). Whales in 

this stock winter off Mexico and the 

Revillagigedo Archipelago and summer 

primarily in Alaska waters (Martien et 

al., 2021; Carretta et al., 2023; Young et 

al., 2023). 


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The most comprehensive photoidentification data available suggest that 

approximately 89 percent of all 

humpback whales in the Gulf of Alaska 

are members of the Hawaii stock, 11 

percent are from the Mexico-North 

Pacific stock, and less than 1 percent are 

from the Western North Pacific stock 

(Wade, 2021). Members of different 

stocks are known to intermix in feeding 

grounds. 

On October 9, 2019, NMFS proposed 

to designate critical habitat for the 

Western North Pacific, Mexico, and 

Central America DPSs of humpback 

whales (84 FR 54354). NMFS issued a 

final rule on April 21, 2021 to designate 

critical habitat for ESA-listed humpback 

whales pursuant to section 4 of the ESA 

(86 FR 21082). There is no designated 

critical habitat for humpback whales in 

or near the Project area (86 FR 21082, 

April 21, 2021), nor does the project 

overlap with any known BIAs. 

Humpback whales are encountered 

regularly in lower Cook Inlet and 

occasionally in mid-Cook Inlet; 

however, sightings are rare in upper 

Cook Inlet (e.g., Witteveen et al., 2011). 

During aerial surveys conducted in 

summers between 2005 and 2012, 

Shelden et al. (2013) reported dozens of 

sightings in lower Cook Inlet, a handful 

of sightings in the vicinity of Anchor 

Point and in lower Cook Inlet, and no 

sightings north of 60° N latitude. NMFS 

changed to a biennial survey schedule 

starting in 2014 after analysis showed 

there would be little reduction in the 

ability to detect a trend given the 

current growth rate of the population 

(Hobbs, 2013). No survey took place in 

2020. Instead, consecutive surveys took 

place in 2021 and 2022 (Shelden et al., 

2022). During the 2014–2022 aerial 

surveys, sightings of humpback whales 

were recorded in lower Cook Inlet and 

mid-Cook Inlet, but none were observed 

in upper Cook Inlet (Shelden et al., 

2015b, 2017, 2019, 2022). Vessel-based 

observers participating in the Apache 

Corporation’s 2014 survey operations 

recorded three humpback whale 

sightings near Moose Point in upper 

Cook Inlet and two sightings near 

Anchor Point, while aerial and landbased observers recorded no humpback 

whale sightings, including in the upper 

inlet (Lomac-MacNair et al., 2014). 

Observers monitoring waters between 

Point Campbell and Fire Island during 

summer and fall 2011 and spring and 

summer 2012 recorded no humpback 

whale sightings (Brueggeman et al., 

2013). Monitoring of Turnagain Arm 

during ice-free months between 2006 

and 2014 yielded one humpback whale 

sighting (McGuire, unpublished data, 

cited in LGL Alaska Research 

Associates, Inc., and DOWL, 2015). 

There have been few sightings of 

humpback whales in the vicinity of the 

proposed project area. Humpback 

whales were not documented during 

POA construction or scientific 

monitoring from 2005 to 2011, in 2016, 

or during 2020 (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). Observers 

monitoring the Ship Creek Small Boat 

Launch from August 23 to September 

11, 2017 recorded two sightings, each of 

a single humpback whale, which was 

presumed to be the same individual 

(POA, 2017). One other humpback 

whale sighting has been recorded for the 

immediate vicinity of the project area. 

This event involved a stranded whale 

that was sighted near a number of 

locations in upper Cook Inlet before 

washing ashore at Kincaid Park in 2017; 

it is unclear as to whether the 

humpback whale was alive or deceased 

upon entering Cook Inlet waters. 

Another juvenile humpback stranded in 

Turnagain Arm in April 2019 near mile 

86 of the Seward Highway. One 

additional humpback whale was 

observed in July during 2022 

transitional dredging monitoring (61N 

Environmental, 2022c). No humpback 

whales were observed during the 2020 

to 2021 PCT construction monitoring, 

the NMFS marine mammal monitoring, 

or the 2022 SFD construction 

monitoring from April to June (61N 

Environmental, 2021, 2022a, 2022b, 

2022c; Easley-Appleyard and Leonard, 

2022). 

Killer Whale 

Killer whales are rare in Cook Inlet, 

and there are no known BIAs for this 

species in Cook Inlet. Most sightings of 

killer whales in the area are in lower 

Cook Inlet (Shelden et al., 2013). The 

infrequent sightings of killer whales that 

are reported in upper Cook Inlet tend to 

occur when their primary prey 

(anadromous fish for resident killer 

whales and beluga whales for transient 

killer whales) are also in the area 

(Shelden et al., 2003). During CIBW 

aerial surveys between 1993 and 2012, 

killer whales were sighted in lower 

Cook Inlet 17 times, with a total of 70 

animals (Shelden et al., 2013); no killer 

whales were observed in upper Cook 

Inlet during this time. Surveys over 20 

years by Shelden et al. (2003) 

documented an increase in CIBW 

sightings and strandings in upper Cook 

Inlet beginning in the early 1990s. 

Several of these sightings and strandings 

reported evidence of killer whale 

predation on CIBWs. The pod sizes of 

killer whales preying on CIBWs ranged 

from one to six individuals (Shelden et 

al., 2003). Passive acoustic monitoring 

efforts throughout Cook Inlet 

documented killer whales at the Beluga 

River, Kenai River, and Homer Spit, 

although they were not encountered 

within Knik Arm (Castellote et al., 

2016). These detections were likely 

resident killer whales. Transient killer 

whales likely have not been acoustically 

detected due to their propensity to move 

quietly through waters to track prey 

(Small, 2010; Lammers et al., 2013). 

Few killer whales, if any, are expected 

to approach or be in the vicinity of the 

proposed project area. No killer whales 

were spotted in the vicinity of the POA 

during surveys by Funk et al. (2005), 

Ireland et al. (2005), or Brueggeman et 

al. (2007, 2008a, 2008b). Killer whales 

have also not been documented during 

any POA construction or scientific 

monitoring from 2005 to 2011, in 2016, 

or in 2020 (Prevel-Ramos et al., 2006; 

Markowitz and McGuire, 2007; Cornick 

and Saxon-Kendall, 2008; ICRC, 2009, 

2010, 2011, 2012; Cornick et al., 2010, 

2011; Cornick and Pinney, 2011; 

Cornick and Seagars, 2016; 61N 

Environmental, 2021). Two killer 

whales, one male and one juvenile of 

unknown sex, were sighted offshore of 

Point Woronzof in September 2021 

during PCT Phase 2 construction 

monitoring (61N Environmental, 2022a). 

The pair of killer whales moved up Knik 

Arm, reversed direction near Cairn 

Point, and moved southwest out of Knik 

Arm toward the open water of Upper 

Cook Inlet. No killer whales were 

sighted during the 2021 NMFS marine 

mammal monitoring or the 2022 

transitional dredging and SFD 

construction monitoring that occurred 

between May and June 2022 (61N 

Environmental, 2022b, 2022c; EasleyAppleyard and Leonard, 2022). 

Beluga Whale 

Five stocks of beluga whales are 

recognized in Alaska: the Beaufort Sea 

stock, eastern Chukchi Sea stock, 

eastern Bering Sea stock, Bristol Bay 

stock, and Cook Inlet stock (Young et 

al., 2023). The Cook Inlet stock is 

geographically and genetically isolated 

from the other stocks (O’Corry-Crowe et 

al., 1997; Laidre et al., 2000) and resides 

year-round in Cook Inlet (Laidre et al., 

2000; Castellote et al., 2020). Only the 

CIBW stock inhabits the proposed 

project area. CIBWs were designated as 

a DPS and listed as endangered under 

the ESA in October 2008 (73 FR 62919, 

October 10, 2008). 


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On June 15, 2023, NMFS released an 

updated abundance estimate for CIBWs 

(Goetz et al., 2023) that incorporates 

aerial survey data from June 2021 and 

2022, which represents an update from 

the most recent SAR (Young et al., 2023) 

and suggest that the CIBW population is 

stable or may be slightly increasing. The 

methodology in the 2023 report is the 

same as that used for NMFS’s SARs 

(Young et al. 2023) and incorporates the 

same time-series of data from previous 

years. The only change was the 

inclusion of more recent data from 2021 

and 2022 surveys; the 2021 data 

collection efforts were delayed from 

2020 due to COVID–19. Goetz et al. 

(2023) estimated that the population 

size is currently between 290 and 386, 

with a median best estimate of 331. We 

have determined that Goetz et al. (2023) 

represents the most recent and best 

available science. 

Goetz et al. (2023) also present an 

analysis of population trends for the 

most recent 10-year period (2012–2022). 

The addition of data from the 2021 and 

2022 survey years in the analysis 

resulted in a 65.1 percent probability 

that the CIBW population is now 

increasing at 0.9 percent per year (95 

percent prediction interval of ¥3 to 5.7 

percent). This increase drops slightly to 

0.2 percent per year (95 percent 

prediction interval of ¥1.8 to 2.6 

percent) with a 60 percent probability 

that the CIBW population is increasing 

more than 1 percent per year when data 

from 2021, which had limited survey 

coverage due to poor weather, are 

excluded from the analysis. Median 

group size estimates in 2021 and 2022 

were 34 and 15, respectively (Goetz et 

al., 2023). NMFS has determined that 

the carrying capacity of Cook Inlet is 

1,300 CIBWs (65 FR 34590, May 31, 

2000) based on historical CIBW 

abundance estimated by Calkins (1989). 

Additional information may be found in 

NMFS’ 2023 report on the abundance 

and trend of CIBWs in Cook Inlet in 

June 2021 and June 2022, available 

online at https://www.fisheries.

noaa.gov/resource/document/ 

abundance-and-trend-belugasdelphinapterus-leucas-cook-inletalaska-june-2021-and. 

Live stranding events of CIBWs have 

been regularly observed in upper Cook 

Inlet. This can occur when an 

individual or group of individuals 

strands as the tide recedes. Most live 

strandings have occurred in Knik Arm 

and Turnagain Arm, which are shallow 

and have large tidal ranges, strong 

currents, and extensive mudflats. Most 

whales involved in a live stranding 

event survive, although some associated 

deaths may not be observed if the 

whales die later from live-strandingrelated injuries (Vos and Shelden, 2005; 

Burek-Huntington et al., 2015). Between 

2014 and 2018, there were reports of 

approximately 79 CIBWs involved in 3 

known live stranding events plus 1 

suspected live stranding event with two 

associated deaths reported (NMFS, 

2016b; NMFS, unpublished data; Muto 

et al., 2020). In 2014, necropsy results 

from two whales found in Turnagain 

Arm suggested that a live stranding 

event contributed to their deaths as both 

had aspirated mud and water. No live 

stranding events were reported prior to 

the discovery of these dead whales 

suggesting that not all live stranding 

events are observed. 

Another source of CIBW mortality in 

Cook Inlet is predation by transient-type 

(mammal-eating) killer whales (NMFS, 

2016b; Shelden et al., 2003). No humancaused mortality or serious injury of 

CIBWs through interactions with 

commercial, recreational, and 

subsistence fisheries or because of other 

human-caused events (e.g., 

entanglement in marine debris, ship 

strikes) has been recently documented, 

and subsistence harvesting of CIBWs 

has not occurred since 2008 (NMFS, 

2008b). 

Recovery Plan. The Final Recovery 

Plan for CIBW was published in the 

Federal Register on January 5, 2017 (82 

FR 1325), available online at https://

www.fisheries.noaa.gov/resource/ 

document/recovery-plan-cook-inletbeluga-whale-delphinapterus-leucas. 

In its Recovery Plan (82 FR 1325, 

January 5, 2017), NMFS identified 

several potential threats to CIBWs, 

including: (1) high concern: catastrophic 

events (e.g., natural disasters, spills, 

mass strandings), cumulative effects of 

multiple stressors, and noise; (2) 

medium concern: disease agents (e.g., 

pathogens, parasites, and harmful algal 

blooms), habitat loss or degradation, 

reduction in prey, and prohibited take 

(e.g., entanglements, strikes, poaching or 

intentional harassment, and close 

approaches by private vessels); and (3) 

low concern: pollution, predation, and 

subsistence harvest. The recovery plan 

did not treat climate change as a distinct 

threat but rather as a consideration in 

the threats of high and medium concern. 

Other potential threats most likely to 

result in direct human-caused mortality 

or serious injury of this stock include 

vessel strikes. 

Critical Habitat. On April 11, 2011, 

NMFS designated two areas of critical 

habitat for CIBW (76 FR 20179). The 

designation includes 7,800 km2 of 

marine and estuarine habitat within 

Cook Inlet, encompassing 

approximately 1,909 km2 in Area 1 and 

5,891 km2 in Area 2 (see figure 1 in 76 

FR 20179). Area 1 of the CIBW critical 

habitat encompasses all marine waters 

of Cook Inlet north of a line connecting 

Point Possession (lat. 61.04° N, long. 

150.37° W) and the mouth of Three Mile 

Creek (lat. 61.08.55° N, long. 151.04.40° 

W), including waters of the Susitna, 

Little Susitna, and Chickaloon Rivers 

below mean higher high water. From 

spring through fall, Area 1 critical 

habitat has the highest concentration of 

CIBWs due to its important foraging and 

calving habitat. Area 2 critical habitat 

has a lower concentration of CIBWs in 

spring and summer but is used by 

CIBWs in fall and winter. Critical 

habitat does not include two areas of 

military usage: the Eagle River Flats 

Range on Fort Richardson and military 

lands of JBER between Mean Higher 

High Water and MHW. Additionally, the 

POA, adjacent navigation channel, and 

turning basin (approximately 6.84 km2) 

were excluded from the critical habitat 

designation due to national security 

reasons (76 FR 20180, April 11, 2011). 

The POA exclusion area is within Area 

1, however, marine mammal monitoring 

results from the POA suggest that this 

exclusion area is not a particularly 

important feeding or calving area. 

CIBWs have been occasionally 

documented to forage around Ship 

Creek (south of the POA) but are 

typically transiting through the area to 

other, potentially richer, foraging areas 

to the north (e.g., Six Mile Creek, Eagle 

River, Eklutna River) (e.g., 61N 

Environmental, 2021, 2022a, 2022b, 

2022c, Easley-Appleyard and Leonard, 

2022). These locations contain 

predictable salmon runs, an important 

food source for CIBWs, and the timing 

of these runs has been correlated with 

CIBW movements into the upper 

reaches of Knik Arm (Ezer et al., 2013). 

More information on CIBW critical 

habitat can be found at https://

www.fisheries.noaa.gov/action/criticalhabitat-cook-inlet-beluga-whale. 

The designation identified the 

following Primary Constituent Elements 

(PCE), essential features important to 

the conservation of the CIBW: 

(1) Intertidal and subtidal waters of 

Cook Inlet with depths of less than 9 m 

(MLLW) and within 8 km of high- and 

medium-flow anadromous fish streams; 

(2) Primary prey species, including 

four of the five species of Pacific salmon 

(chum (Oncorhynchus keta), sockeye 

(Oncorhynchus nerka), Chinook 

(Oncorhynchus tshawytscha), and coho 

(Oncorhynchus kisutch)), Pacific 

eulachon (Thaleichthys pacificus), 

Pacific cod (Gadus macrocephalus), 

walleye pollock (Gadus 

chalcogrammus), saffron cod (Eleginus 


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gracilis), and yellowfin sole (Limanda 

aspera); 

(3) The absence of toxins or other 

agents of a type or amount harmful to 

CIBWs; 

(4) Unrestricted passage within or 

between the critical habitat areas; and 

(5) The absence of in-water noise at 

levels resulting in the abandonment of 

habitat by CIBWs. 

The area around the POA, while 

exempted from the Critical Habitat 

designation due to national security 

issues, does contain the requisite 

bathymetric features in the first PCE, as 

well as the presence of primary prey 

species. However, given the 

industrialized nature of the POA and 

the historical use of the site from the 

early 1900s, the other physical features 

are more difficult to confirm. Sediment 

contamination was examined during a 

2008 U.S. Army Corps of Engineers 

dredging project near the Port, and 

contaminant levels of volatile and semivolatile organic compounds, total 

recoverable petroleum hydrocarbons, 

PCBs, pesticides, cadmium, mercury, 

selenium, silver, arsenic, barium, 

chromium, and lead were found to be 

suitable for in-water discharge (USACE 

2008). Ambient and background noise 

levels at the POA have been measured 

and are addressed quantitatively later in 

this document; briefly, noise levels are 

elevated due to both anthropogenic 

activities (i.e., commercial shipping, 

dredging, and construction) and normal 

environmental factors (e.g., high current 

velocity, ice movement, seismic 

activity). While neither contaminants 

nor noise have been shown to approach 

the ‘‘harmful’’ and ‘‘habitat 

abandonment’’ thresholds described in 

the PCEs, the concentration of both 

stressors is highest closer to the POA 

facilities, within the exemption area, 

ultimately degrading the habitat at POA 

relative to the surrounding areas. In 

total, the exempted area surrounding the 

POA represents approximately 0.35 

percent of the designated Critical 

Habitat Area 1. 

Biologically Important Areas. Wild et 

al. (2023) delineated portions of Cook 

Inlet, including near the proposed 

project area, as a BIA for the small and 

resident population of CIBWs based on 

scoring methods outlined by Harrison et 

al. (2023) (see https://oceannoise.

noaa.gov/biologically-important-areas 

for more information). The BIA is used 

year-round by CIBWs for feeding and 

breeding, and there are limits on food 

supply such as salmon runs and 

seasonal movement of other fish species 

(Wild et al., 2023). The boundary of the 

CIBW BIA is consistent with NMFS’ 

critical habitat designation and does not 

include the aforementioned exclusion 

areas (e.g., the POA and surrounding 

waters) (Wild et al., 2023). 

Foraging Ecology. CIBWs feed on a 

wide variety of prey species, 

particularly those that are seasonally 

abundant. From late spring through 

summer, most CIBW stomachs sampled 

contained salmon, which corresponded 

to the timing of fish runs in the area. 

Anadromous smolt and adult fish 

aggregate at river mouths and adjacent 

intertidal mudflats (Calkins, 1989). All 

five Pacific salmon species (i.e., 

Chinook, pink (Oncorhynchus 

gorbuscha), coho, sockeye, and chum) 

spawn in rivers throughout Cook Inlet 

(Moulton, 1997; Moore et al., 2000). 

Overall, Pacific salmon represent the 

highest percent frequency of occurrence 

of prey species in CIBW stomachs. This 

suggests that their spring feeding in 

upper Cook Inlet, principally on fat-rich 

fish, such as salmon and eulachon, is 

important to the energetics of these 

animals (NMFS, 2016b). 

The nutritional quality of Chinook 

salmon in particular is unparalleled, 

with an energy content four times 

greater than that of a Coho salmon. It is 

suggested the decline of the Chinook 

salmon population has left a nutritional 

void in the diet of the CIBWs that no 

other prey species can fill in terms of 

quality or quantity (Norman et al., 2020, 

2022). 

In fall, as anadromous fish runs begin 

to decline, CIBWs consume fish species 

(cod and bottom fish) found in 

nearshore bays and estuaries. Stomach 

samples from CIBWs are not available 

for winter (December through March), 

although dive data from CIBWs tagged 

with satellite transmitters suggest that 

they feed in deeper waters during 

winter (Hobbs et al., 2005), possibly on 

such prey species as flatfish, cod, 

sculpin, and pollock. 

Fish runs in the Anchorage and 

Matanuska-Susitna area include 

Chinook (May–August), sockeye (June– 

September), coho (July–September), pin 

(July–August), and chum (July– 

September) salmon, as well as dolly 

varden, rainbow and lake trout, 

northern pike, burbot, grayling, smelt, 

and whitefish. In proximity to the POA, 

anadromous fish runs occur at Ship 

Creek, which is heavily used by 

recreational anglers. On June 26, 2024, 

the Alaska Department of Fish and 

Game (ADF&G) issued an emergency 

closure of recreational fishing on Ship 

Creek until July 13, 2024, and limited 

Chinook catching to catch-and-release 

for the remainder of the season due to 

low returns of Chinook in the creek. 

ADF&G anticipates a poor return of this 

species throughout Knik Arm for 2024, 

in keeping with a trend of declining 

Chinook Runs throughout Cook Inlet 

since 2008 (ADF&G 2019). The Gulf of 

Alaska Chinook salmon is currently 

under review for listing under the ESA 

(89 FR 45815, May 24, 2024). 

Distribution in Cook Inlet. The CIBW 

stock remains within Cook Inlet 

throughout the year, showing only small 

seasonal shifts in distribution (Goetz et 

al., 2012a; Lammers et al., 2013; 

Castallotte et al., 2015; Shelden et al., 

2015a, 2018; Lowery et al., 2019). 

During spring and summer, CIBWs 

generally aggregate near the warmer 

waters of river mouths where prey 

availability is high and predator 

occurrence is low (Moore et al., 2000; 

Shelden and Wade, 2019; McGuire et 

al., 2020). In particular, CIBW groups 

are seen in the Susitna River Delta 

approximately 36 km (23 mi) to the west 

of the POA across the mouth of Knik 

arm in Upper Cook Inlet, the Beluga 

River (approximately 55 km (34 mi) 

west) and along the shore to the Little 

Susitna River (21 km (13 mi) west), 

within all of Knik Arm, and along the 

shores of Chickaloon Bay to the south of 

Anchorage, across Turnagain Arm 

(figure 3). Small groups were recorded 

farther south in Kachemak Bay, Redoubt 

Bay (Big River), and Trading Bay 

(McArthur River) prior to 1996 but 

rarely thereafter. Since the mid-1990s, 

most CIBWs (96 to 100 percent) 

aggregate in shallow areas near river 

mouths in upper Cook Inlet, and they 

are only occasionally sighted in the 

central or southern portions of Cook 

Inlet during summer (Hobbs et al., 

2008). Almost the entire population can 

be found in northern Cook Inlet from 

late spring through the summer and into 

the fall (Muto et al., 2020). 


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Data from tagged whales (14 tags 

deployed July 2000 through March 

2003) show that CIBWs use upper Cook 

Inlet intensively between summer and 

late autumn (Hobbs et al., 2005). CIBWs 

tagged with satellite transmitters 

continue to use Knik Arm, Turnagain 

Arm, and Chickaloon Bay as late as 

October, but some range into lower 

Cook Inlet to Chinitna Bay, Tuxedni 

Bay, and Trading Bay (McArthur River) 

in fall (Hobbs et al., 2005, 2012). From 

September through November, CIBWs 

move between Knik Arm, Turnagain 

Arm, and Chickaloon Bay (Hobbs et al., 

2005; Goetz et al., 2012b). By December, 

CIBWs are distributed throughout the 

upper to mid-inlet. From January into 

March, they move as far south as Kalgin 

Island and slightly beyond in central 

offshore waters. CIBWs make occasional 

excursions into Knik Arm and 

Turnagain Arm in February and March 

in spite of ice cover (Hobbs et al., 2005). 

Although tagged CIBWs move widely 

around Cook Inlet throughout the year, 

there is no indication of seasonal 

migration in and out of Cook Inlet 

(Hobbs et al., 2005). Data from NMFS 

aerial surveys, opportunistic sighting 

reports, and corrected satellite-tagged 

CIBWs confirm that they are more 

widely dispersed throughout Cook Inlet 

during winter (November–April), with 

animals found between Kalgin Island 

and Point Possession. Generally fewer 

observations of CIBWs are reported from 

the Anchorage and Knik Arm area from 

November through April as documented 


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Figure 3 - Overview of Cook Inlet Geography. 
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in the designation of Critical Habitat (76 

FR 20179, April 11, 2011; Rugh et al., 

2000, 2004). 

The NMFS Marine Mammal Lab has 

conducted long-term passive acoustic 

monitoring demonstrating seasonal 

shifts in CIBW concentrations 

throughout Cook Inlet. Castellote et al. 

(2015) conducted long-term acoustic 

monitoring at 13 locations throughout 

Cook Inlet between 2008 and 2015: 

North Eagle Bay, Eagle River Mouth, 

South Eagle Bay, Six Mile, Point 

MacKenzie, Cairn Point, Fire Island, 

Little Susitna, Beluga River, Trading 

Bay, Kenai River, Tuxedni Bay, and 

Homer Spit; the former 6 stations being 

located within Knik Arm. In general, the 

observed seasonal distribution is in 

accordance with descriptions based on 

aerial surveys and satellite telemetry: 

CIBW detections are higher in the upper 

inlet during summer, peaking at Little 

Susitna, Beluga River, and Eagle Bay, 

followed by fewer detections at those 

locations during winter. Higher 

detections in winter at Trading Bay, 

Kenai River, and Tuxedni Bay suggest a 

broader CIBW distribution in the lower 

inlet during winter, particularly in 

Tuxedni Bay in the months of 

September through March (Castellote et 

al., 2015, 2018, 2024; Castellote et al. 

2024). 

Goetz et al. (2012b) modeled habitat 

preferences using NMFS’ 1994–2008 

June abundance survey data. In large 

areas, such as the Susitna Delta (Beluga 

to Little Susitna Rivers) and Knik Arm, 

there was a high probability that CIBWs 

were in larger groups. CIBW presence 

and acoustic foraging behavior also 

increased closer to rivers with Chinook 

salmon runs, such as the Susitna River 

(e.g., Castellote et al., 2021). Movement 

has been correlated with the peak 

discharge of seven major rivers 

emptying into Cook Inlet. Boat-based 

surveys from 2005 to the present 

(McGuire and Stephens, 2017) and 

results from passive acoustic monitoring 

across the entire inlet (Castellote et al., 

2015) also support seasonal patterns 

observed with other methods. Based on 

long-term passive acoustic monitoring, 

seasonally, foraging behavior was more 

prevalent during summer, particularly 

at upper inlet rivers, than during winter. 

Foraging index was highest at Little 

Susitna, with a peak in July-August and 

a secondary peak in May, followed by 

Beluga River and then Eagle Bay; 

monthly variation in the foraging index 

indicates CIBWs shift their foraging 

behavior among these three locations 

from April through September. 

CIBWs are believed to mostly calve in 

the summer and concurrently breed 

between late spring and early summer 

(NMFS, 2016b), primarily in upper Cook 

Inlet. McGuire et al. (2020) documented 

three suspected calving events between 

July and September with no neonates 

observed during surveys conducted 

from April to June. The first neonates 

encountered during each field season 

from 2005 through 2015 were always 

seen in the Susitna River Delta in July. 

Important calving grounds are thought 

to be located near the river mouths of 

upper Cook Inlet—both potential births 

documented in July were at the Susitna 

River Delta; the third was in Turnagain 

Arm in September (McGuire et al., 

2020). The photographic identification 

team’s documentation of the dates of the 

first neonate of each year indicate that 

calving begins in mid-late July/early 

August, generally coinciding with the 

observed timing of annual maximum 

group size. Probable mating behavior of 

CIBWs was observed during all months 

of the aerial surveys (McGuire et al., 

2020). Young CIBWs are nursed for 2 

years and may continue to associate 

with their mothers for a considerable 

time thereafter (Colbeck et al., 2013). 

Demographic rates were modeled for 

this population, indicating that low 

survival of non-breeding (i.e., subadult, 

male, and non-breeding adult female) 

CIBWs and general low reproductive 

rates are likely contributing to the nonrecovery of the population (Himes Boor 

et al., 2022). 

Presence in Project Area. Knik Arm is 

one of three areas in upper Cook Inlet 

where CIBWs are concentrated during 

spring, summer, and early fall. Most 

CIBWs observed in or near the POA are 

transiting between upper Knik Arm and 

other portions of Cook Inlet, and the 

POA itself is not considered highquality foraging habitat. CIBWs tend to 

follow their anadromous prey and travel 

in and out of Knik Arm with the tides. 

The predictive habitat model derived by 

Goetz et al. (2012a) indicated that the 

highest predicted densities of CIBWs are 

in Knik Arm near the mouth of the 

Susitna River and in Chickaloon Bay. 

The model suggests that the density of 

CIBWs ranges from 0 to 1.12 whales per 

km2 in Cook Inlet but is lower at the 

mouth of Knik Arm, near the POA, 

ranging between approximately 0.013 

and 0.062 whales per km2. The 

distribution presented by Goetz et al. 

(2012a) is generally consistent with 

CIBW distribution documented in upper 

Cook Inlet throughout ice-free months 

(NMFS, 2016b). 

Several marine mammal monitoring 

programs and studies have been 

conducted at or near the POA during the 

last 17 years. These studies offer some 

of the best available information on the 

presence of CIBWs in the proposed 

project area. Studies that occurred prior 

to 2020 are summarized in Section 4.5.5 

of the POA’s application. More recent 

programs, which most accurately 

portray current information regarding 

CIBW presence in the proposed project 

area, are summarized here. 

PCT Construction Monitoring (2020– 

2021). A marine mammal monitoring 

program was implemented during 

construction of the PCT in 2020 (Phase 

1) and 2021 (Phase 2), as required by the 

NMFS IHAs (85 FR 19294, April 6, 

2020). PCT Phase 1 construction 

included impact installation of 48-in 

(122-cm) attenuated piles; impact 

installation of 36-in (91-cm) and 48-in 

(122-cm) unattenuated piles; vibratory 

installation of 24-in (61-cm), 36-in (91- 

cm), and 48-in (122 cm) attenuated and 

unattenuated piles; and vibratory 

installation of an unattenuated 72-in 

(183-cm) casing for a confined bubble 

curtain across 95 days. PCT Phase 2 

construction included vibratory 

installation of 36-in (91-cm) attenuated 

piles and impact and vibratory 

installation of 144-in (366-cm) 

attenuated breasting and mooring 

dolphins across 38 days. Marine 

mammal monitoring in 2020 occurred 

during 128 non-consecutive days with a 

total of 1,238.7 hours of monitoring 

from April 27 to November 24, 2020 

(61N Environmental, 2021). Marine 

mammal monitoring in 2021 occurred 

during 74 non-consecutive days with a 

total of 734.9 hours of monitoring from 

April 26 to June 24 and September 7 to 

29, 2021 (61N Environmental, 2022a). A 

total of 1,504 individual CIBWs across 

377 groups were sighted during PCT 

construction monitoring. Sixty-five and 

67 percent of CIBW observations 

occurred on non-pile driving days or 

before pile driving occurred on a given 

day during PCT Phase 1 and PCT Phase 

2 construction, respectively. 

The monitoring effort and data 

collection were conducted before, 

during, and after pile driving activities 

from four locations as stipulated by the 

PCT IHAs (85 FR 19294, April 6, 2020): 

(1) the Anchorage Public Boat Dock by 

Ship Creek, (2) the Anchorage 

Downtown Viewpoint near Point 

Woronzof, (3) the PCT construction site, 

and (4) the North End (North Extension) 

at the north end of the POA, near Cairn 

Point. Marine mammal sighting data 

from April to September both before, 

during, and after pile driving indicate 

that CIBWs swam near the POA and 

lingered there for periods of time 

ranging from a few minutes to a few 

hours. CIBWs were most often seen 

traveling at a slow or moderate pace, 

either from the north near Cairn Point 

or from the south or milling at the 


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mouth of Ship Creek. Groups of CIBWs 

were also observed swimming north and 

south in front of the PCT construction 

and did not appear to exhibit avoidance 

behaviors either before, during, or after 

pile driving activities (61N 

Environmental, 2021, 2022a). CIBW 

sightings in June were concentrated on 

the west side of Knik Arm from the 

Little Susitna River Delta to Port 

MacKenzie. From July through 

September, CIBWs were most often seen 

milling and traveling on the east side of 

Knik Arm from Point Woronzof to Cairn 

Point (61N Environmental, 2021, 

2022a). 

SFD Construction Monitoring and 

Transitional Dredging (2022). In 2022, a 

marine mammal monitoring program 

almost identical to that used during PCT 

construction was implemented during 

construction of the SFD, as required by 

the NMFS IHA (86 FR 50057, September 

7, 2021). SFD construction included the 

vibratory installation of ten 36-in (91- 

cm) attenuated plumb piles and two 

unattenuated battered piles (61N 

Environmental, 2022b). Marine mammal 

monitoring was conducted during 13 

non-consecutive days with a total of 

108.2 hours of monitoring observation 

from May 20 through June 11, 2022 

(61N Environmental, 2022b). Forty-one 

individual CIBWs across 9 groups were 

sighted (61N Environmental, 2022b). 

One group was observed on a day with 

no pile-driving, three groups were seen 

on days before pile driving activities 

started, and five groups were seen 

during vibratory pile driving activities 

(61N Environmental, 2022b). 

During SFD construction, the position 

of the Ship Creek monitoring station 

was adjusted to allow monitoring of a 

portion of the shoreline north of Cairn 

Point that could not be seen by the 

station at the northern end of the POA 

(61N Environmental, 2022b). Eleven 

protected species observers (PSOs) 

worked from four monitoring stations 

located along a 9-km (6-mi) stretch of 

coastline surrounding the POA. The 

monitoring effort and data collection 

were conducted at the following four 

locations: (1) Point Woronzof 

approximately 6.5 km (4 mi) southwest 

of the SFD, (2) the promontory near the 

boat launch at Ship Creek, (3) the SFD 

project site, and (4) the northern end of 

the POA (61N Environmental, 2022b). 

Ninety groups comprised of 529 

CIBWs were also sighted during the 

transitional dredging monitoring that 

occurred from May 3 to 15, 2022 and 

June 27 to August 24, 2022 (61N 

Environmental, 2022b). Of the nine 

groups of CIBWs sighted during SFD 

construction, traveling was recorded as 

the primary behavior for each group 

(61N Environmental, 2022b). CIBWs 

traveled and milled between the SFD 

construction area, Ship Creek, and areas 

to the south of the POA for more than 

an hour at a time, delaying some 

construction activities. 

Harbor Porpoise 

Harbor porpoises occur throughout 

Cook Inlet with passive acoustic 

detections being more prevalent in 

lower Cook Inlet. Although harbor 

porpoises have been frequently 

observed during aerial surveys in Cook 

Inlet (Shelden et al., 2014), most 

sightings are of single animals and are 

concentrated at Chinitna and Tuxedni 

bays on the west side of lower Cook 

Inlet (Rugh et al., 2005). The occurrence 

of larger numbers of porpoise in the 

lower Cook Inlet may be driven by 

greater availability of preferred prey and 

possibly less competition with CIBWs as 

CIBWs move into upper inlet waters to 

forage on Pacific salmon during the 

summer months (Shelden et al., 2014). 

There are no known BIAs for harbor 

porpoise in Cook Inlet. 

An increase in harbor porpoise 

sightings in upper Cook Inlet has been 

observed over recent decades (e.g., 61N 

Environmental, 2021, 2022a; Shelden et 

al., 2014). Small numbers of harbor 

porpoises have been consistently 

reported in upper Cook Inlet between 

April and October (Prevel-Ramos et al., 

2008). The overall increase in the 

number of harbor porpoise sightings in 

upper Cook Inlet is unknown, although 

it may be an artifact from increased 

studies and marine mammal monitoring 

programs in upper Cook Inlet. It is also 

possible that the apparent contraction in 

the CIBW’s range has opened up 

previously occupied CIBW range to 

harbor porpoises (Shelden et al., 2014). 

Harbor porpoises have been observed 

within Knik Arm during monitoring 

efforts from 2005 to 2016. Between 

April 27 and November 24, 2020, 18 

harbor porpoises were observed near the 

POA during the PCT Phase 1 

construction monitoring (61N 

Environmental, 2021). Twenty-seven 

harbor porpoises were observed near the 

POA during the PCT Phase 2 

construction monitoring conducted 

between April 26 and September 29, 

2021 (61N Environmental, 2022a). 

During NMFS marine mammal 

monitoring conducted in 2021, one 

harbor porpoise was observed in August 

and six harbor porpoises were observed 

in October (Easley-Appleyard and 

Leonard, 2022). During 2022, five harbor 

porpoises were sighted during 

transitional dredging monitoring (61N 

Environmental, 2022c). No harbor 

porpoises were sighted at the POA 

during the 2022 SFD construction 

monitoring that occurred between May 

and June 2022 (61N Environmental, 

2022b). 

Steller Sea Lion 

Two DPSs of Steller sea lion occur in 

Alaska: the western DPS and the eastern 

DPS. The western DPS includes animals 

that occur west of Cape Suckling, 

Alaska and therefore, includes 

individuals within the Project area. The 

western DPS was listed under the ESA 

as threatened in 1990 (55 FR 49204, 

November 26, 1990), and its continued 

population decline resulted in a change 

in listing status to endangered in 1997 

(62 FR 24345, May 5, 1997). Since 2000, 

studies indicate that the population east 

of Samalga Pass (i.e., east of the 

Aleutian Islands) has increased and is 

potentially stable (Young et al., 2023). 

NMFS designated critical habitat for 

Steller sea lions on August 27, 1993 (58 

FR 45269). The critical habitat 

designation for the Western DPS of was 

determined to include a 37-km (20- 

nautical mile) buffer around all major 

haul-outs and rookeries, and associated 

terrestrial, atmospheric, and aquatic 

zones, plus three large offshore foraging 

areas, none of which occurs in the 

project area. There are no known BIAs 

for Steller sea lions in Cook Inlet. 

Within Cook Inlet, Steller sea lions 

primarily inhabit lower Cook Inlet. 

However, they occasionally venture to 

upper Cook Inlet and Knik Arm and 

may be attracted to salmon runs in the 

region. Steller sea lions have not been 

documented in upper Cook Inlet during 

CIBW aerial surveys conducted 

annually in June from 1994 through 

2012 and in 2014 (Shelden et al., 2013, 

2015b, 2017; Shelden and Wade, 2019); 

however, there has been an increase in 

individual Steller sea lion sightings near 

the POA in recent years. 

Steller sea lions were observed near 

the POA in 2009, 2016, and 2019 

through 2022 (ICRC, 2009; Cornick and 

Seagars, 2016; POA, 2019; 61N 

Environmental, 2021, 2022a, 2022b, 

2022c). In 2009, there were three Steller 

sea lion sightings that were believed to 

be the same individual (ICRC, 2009). In 

2016, Steller sea lions were observed on 

2 separate days. On May 2, 2016, one 

individual was sighted, while on May 

25, 2016, there were five 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 

five sightings were of the same 

individual sea lion. In 2019, one Steller 

sea lion was observed in June at the 

POA during transitional dredging (POA, 


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2019). There were six sightings of 

individual Steller sea lions near the 

POA during PCT Phase 1 construction 

monitoring (61N Environmental, 2021). 

At least two of these sightings may have 

been re-sights on the same individual. 

An additional seven unidentified 

pinnipeds were observed that could 

have been Steller sea lions or harbor 

seals (61N Environmental, 2021). In 

2021, there were a total of eight 

sightings of individual Steller sea lions 

observed near the POA during PCT 

Phase 2 construction monitoring (61N 

Environmental, 2022a). During NMFS 

marine mammal monitoring, one Steller 

sea lion was observed in August 2021 in 

the middle of the inlet (EasleyAppleyard and Leonard, 2022). In 2022, 

there were three Steller sea lion 

sightings during the transitional 

dredging monitoring and three during 

SFD construction monitoring (61N 

Environmental, 2022b, 2022c). All 

sightings occurred during summer, 

when the sea lions were likely attracted 

to ongoing salmon runs. Sea lion 

observations near the POA may be 

increasing due to more consistent 

observation effort or due to increased 

presence; observations continue to be 

occasional. 

Harbor Seal 

Harbor seals inhabit the coastal and 

estuarine waters of Cook Inlet and are 

observed in both upper and lower Cook 

Inlet throughout most of the year 

(Boveng et al., 2012; Shelden et al., 

2013), though there are no known BIAs 

for this species in this area. Recent 

research on satellite-tagged harbor seals 

observed several movement patterns 

within Cook Inlet (Boveng et al., 2012), 

including a strong seasonal pattern of 

more coastal and restricted spatial use 

during the spring and summer 

(breeding, pupping, molting) and more 

wide-ranging movements within and 

outside of Cook Inlet during the winter 

months, with some seals ranging as far 

as Shumagin Islands. During summer 

months, movements and distribution 

were mostly confined to the west side 

of Cook Inlet and Kachemak Bay, and 

seals captured in lower Cook Inlet 

generally exhibited site fidelity by 

remaining south of the Forelands in 

lower Cook Inlet after release (Boveng et 

al., 2012). In the fall, a portion of the 

harbor seals appeared to move out of 

Cook Inlet and into Shelikof Strait, 

northern Kodiak Island, and coastal 

habitats of the Alaska Peninsula. The 

western coast of Cook Inlet had higher 

usage by harbor seals than eastern coast 

habitats, and seals captured in lower 

Cook Inlet generally exhibited site 

fidelity by remaining south of the 

Forelands in lower Cook Inlet after 

release (south of Nikiski; Boveng et al., 

2012). 

The presence of harbor seals in upper 

Cook Inlet is seasonal. Harbor seals are 

commonly observed along the Susitna 

River and other tributaries within upper 

Cook Inlet during eulachon and salmon 

migrations (NMFS, 2003). The major 

haulout sites for harbor seals are in 

lower Cook Inlet; however, there are a 

few haulout sites in upper Cook Inlet, 

including near the Little and Big Susitna 

rivers, Beluga River, Theodore River, 

and Ivan River (Barbara Mahoney, 

personal communication, November 16, 

2020; Montgomery et al., 2007). During 

CIBW aerial surveys of upper Cook Inlet 

from 1993 to 2012, harbor seals were 

observed 24 to 96 km south-southwest 

of Anchorage at the Chickaloon, Little 

Susitna, Susitna, Ivan, McArthur, and 

Beluga rivers (Shelden et al., 2013). 

Harbor seals have been observed in Knik 

Arm and in the vicinity of the POA 

(Shelden et al., 2013), but they are not 

known to haul out within the proposed 

project area. 

Harbor seals were observed during 

construction monitoring at the POA 

from 2005 through 2011 and in 2016, in 

groups of one to seven individuals 

(Prevel-Ramos et al., 2006; Markowitz 

and McGuire, 2007; Cornick and SaxonKendall, 2008, 2009; Cornick et al., 

2010, 2011; Cornick and Seagars, 2016). 

Harbor seals were also observed near the 

POA during construction monitoring for 

PCT Phase 1 in 2020 and PCT Phase 2 

in 2021, NMFS marine mammal 

monitoring in 2021, and transitional 

dredging monitoring and SFD 

construction monitoring in 2022 (61N 

Environmental, 2021, 2022a, 2022b, 

2022c, Easley-Appleyard and Leonard, 

2022). During the 2020 PCT Phase 1 and 

2021 PCT Phase 2 construction 

monitoring, harbor seals were regularly 

observed in the vicinity of the POA with 

frequent observations near the mouth of 

Ship Creek, located approximately 1,500 

m southeast of the CTR location. Harbor 

seals were observed almost daily during 

2020 PCT Phase 1 construction, with 54 

individuals documented in July, 66 

documented in August, and 44 sighted 

in September (61N Environmental, 

2021). During the 2021 PCT Phase 2 

construction, harbor seals were 

observed with the highest numbers of 

sightings in June (87 individuals) and in 

September (124 individuals) (61 N 

Environmental, 2022a). Over the 13 

days of SFD construction monitoring in 

May and June 2022, 27 harbor seals 

were observed (61N Environmental, 

2022b). Seventy-two groups of 75 total 

harbor seals (3 groups of 2 individuals) 

were observed during transitional 

dredging monitoring in 2022 (61N 

Environmental, 2022c). Sighting rates of 

harbor seals have been highly variable 

and may have increased since 2005. It 

is unknown whether any potential 

increase was due to local population 

increases or habituation to ongoing 

construction activities. It is possible that 

increased sighting rates are correlated 

with more intensive monitoring efforts 

in 2020 and 2021, when the POA used 

11 PSOs spread among four monitoring 

stations. 

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 

decibel (dB) threshold from the 

normalized composite audiograms, with 

the exception for lower limits for lowfrequency 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 and is intended 

to replace the 2018 Technical Guidance 

once finalized. The public comment 

period ended on June 17th, 2024. 

Because NMFS may finalize the 

Guidance prior to taking a final agency 

action on this proposed rulemaking, we 

considered both the 2018 and 2024 

Technical Guidance in our effects and 

estimated take analysis below. Marine 

mammal hearing groups and their 

associated hearing ranges from NMFS 

(2018) and NMFS (2024) are provided in 

tables 5 and 6. In the draft Updated 


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Technical Guidance, mid-frequency 

cetaceans have been re-classified as 

high-frequency cetaceans, and highfrequency cetaceans have been updated 

to very-high-frequency (VHF) cetaceans. 

Additionally, the draft Updated 

Technical Guidance includes in-air data 

for phocid (PA) and otariid (OA) 

pinnipeds. 

TABLE 5—MARINE MAMMAL HEARING GROUPS

[NMFS, 2018] 

Hearing group Generalized 

hearing range * 

Low-frequency (LF) cetaceans (baleen whales) ..................................................................................................................... 7 Hz to 35 kHz. 

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) ........................................... 150 Hz to 160 kHz. 

High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. 

australis).

275 Hz to 160 kHz. 

Phocid pinnipeds (PW) (underwater) (true seals) ................................................................................................................... 50 Hz to 86 kHz. 

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) .............................................................................................. 60 Hz to 39 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 are typically not as broad. Generalized hearing range chosen based on ∼65 dB threshold from normalized composite audiogram, 

with the exception for lower limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation). 

TABLE 6—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 (2018, 2024) for a 

review of available information. 

Potential Effects of the Specified 

Activity on Marine Mammals and Their 

Habitat 

This section provides a discussion of 

the ways in which components of the 

specified activity may impact marine 

mammals and their habitat. The 

Estimated Take of Marine Mammals 

section later in this document includes 

a quantitative analysis of the number of 

individuals that are expected to be taken 

by this activity. The Negligible Impact 

Analysis and Determination section 

considers the content of this section, the 

Estimated Take of Marine Mammals 

section, and the Proposed Mitigation 

section, to draw conclusions regarding 

the likely impacts of these activities on 

the reproductive success or survivorship 

of individuals and whether those 

impacts are reasonably likely to, 

adversely affect the species or stock 

through effects on annual rates of 

recruitment or survival. 

Acoustic effects on marine mammals 

during the specified activities are 

expected to potentially occur from 

vibratory pile installation and removal 

and impact pile installation. The effects 

of underwater noise from the POA’s 

proposed activities have the potential to 

result in Level B harassment of marine 

mammals in the project area and, for 

some species as a result of certain 

activities, Level A harassment. 

Background on Sound 

This section contains a brief technical 

background on sound, on the 

characteristics of certain sound types 

and on metrics used relevant to the 

specified activity and to a discussion of 

the potential effects of the specified 

activities on marine mammals found 

later in this document. For general 

information on sound and its interaction 

with the marine environment, please 

see: Erbe and Thomas (2022); Au and 

Hastings (2008); Richardson et al. 

(1995); Urick (1983); as well as the 

Discovery of Sound in the Sea website 

at https://dosits.org/. 

Sound is a vibration that travels as an 

acoustic wave through a medium such 

as a gas, liquid or solid. Sound waves 

alternately compress and decompress 

the medium as the wave travels. In 

water, sound waves radiate in a manner 

similar to ripples on the surface of a 

pond and may be either directed in a 

beam (narrow beam or directional 

sources) or sound may radiate in all 

directions (omnidirectional sources), as 

is the case for sound produced by the 

construction activities considered here. 

The compressions and decompressions 

associated with sound waves are 

detected as changes in pressure by 

marine mammals and human-made 

sound receptors such as hydrophones. 

Sound travels more efficiently in 

water than almost any other form of 

energy, making the use of sound as a 

primary sensory modality ideal for 

inhabitants of the aquatic environment. 

In seawater, sound travels at roughly 

1,500 meters per second (m/s). In air, 

sound waves travel much more slowly 

at about 340 m/s. However, the speed of 

sound in water can vary by a small 

amount based on characteristics of the 


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transmission medium such as 

temperature and salinity. 

The basic characteristics of a sound 

wave are frequency, wavelength, 

velocity, and amplitude. Frequency is 

the number of pressure waves that pass 

by a reference point per unit of time and 

is measured in hertz (Hz) or cycles per 

second. Wavelength is the distance 

between two peaks or corresponding 

points of a sound wave (length of one 

cycle). Higher frequency sounds have 

shorter wavelengths than lower 

frequency sounds, and typically 

attenuate (decrease) more rapidly with 

distance. The amplitude of a sound 

pressure wave is related to the 

subjective ‘‘loudness’’ of a sound and is 

typically expressed in dB, which are a 

relative unit of measurement that is 

used to express the ratio of one value of 

a power or pressure to another. A sound 

pressure level (SPL) in dB is described 

as the ratio between a measured 

pressure and a reference pressure, and 

is a logarithmic unit that accounts for 

large variations in amplitude; therefore, 

a relatively small change in dB 

corresponds to large changes in sound 

pressure. For example, a 10-dB increase 

is a ten-fold increase in acoustic power. 

A 20-dB increase is then a 100-fold 

increase in power and a 30-dB increase 

is a 1,000-fold increase in power. 

However, a ten-fold increase in acoustic 

power does not mean that the sound is 

perceived as being 10 times louder due 

to the anatomy of mammalian ears. A 

10-dB increase in sound is perceived as 

a doubling of loudness to the human 

ear, and marine mammal studies of 

loudness perception are ongoing 

(Houser et al. 2017). 

The dB is a relative unit comparing 

two pressures; therefore, a reference 

pressure must always be indicated. For 

underwater sound, this is 1 microPascal 

(mPa). For in-air sound, the reference 

pressure is 20 microPascal (mPa). The 

amplitude of a sound can be presented 

in various ways; however, NMFS 

typically considers three metrics: sound 

exposure level (SEL), root-mean-square 

(RMS) SPL, and peak SPL (defined 

below). The source level represents the 

SPL referenced at a standard distance 

from the source, typically 1 m 

(Richardson et al., 1995; American 

National Standards Institute (ANSI, 

2013), while the received level is the 

SPL at the receiver’s position. For pile 

driving activities, the SPL is typically 

referenced at 10 m. 

SEL (represented as dB referenced to 

1 micropascal squared second (re 1 

mPa2-s)) represents the total energy in a 

stated frequency band over a stated time 

interval or event, and considers both 

intensity and duration of exposure. The 

per-pulse SEL (e.g., single strike or 

single shot SEL) is calculated over the 

time window containing the entire 

pulse (i.e., 100 percent of the acoustic 

energy). SEL can also be a cumulative 

metric; it can be accumulated over a 

single pulse (for pile driving this is the 

same as single-strike SEL, above; SELss), 

or calculated over periods containing 

multiple pulses (SELcum). Cumulative 

SEL (SELcum) represents the total energy 

accumulated by a receiver over a 

defined time window or during an 

event. The SEL metric is useful because 

it allows sound exposures of different 

durations to be related to one another in 

terms of total acoustic energy. The 

duration of a sound event and the 

number of pulses, however, should be 

specified as there is no accepted 

standard duration over which the 

summation of energy is measured. 

RMS SPL is equal to 10 times the 

logarithm (base 10) of the ratio of the 

mean-square sound pressure to the 

specified reference value, and given in 

units of dB (International Organization 

for Standardization (ISO), 2017). RMS is 

calculated by squaring all of the sound 

amplitudes, averaging the squares, and 

then taking the square root of the 

average (Urick, 1983). RMS accounts for 

both positive and negative values; 

squaring the pressures makes all values 

positive so that they may be accounted 

for in the summation of pressure levels 

(Hastings and Popper, 2005). This 

measurement is often used in the 

context of discussing behavioral effects, 

in part because behavioral effects, 

which often result from auditory cues, 

may be better expressed through 

averaged units than by peak SPL. For 

impulsive sounds, RMS is calculated by 

the portion of the waveform containing 

90 percent of the sound energy from the 

impulsive event (Madsen, 2005). 

Peak SPL (also referred to as zero-topeak sound pressure or 0-pk) is the 

maximum instantaneous sound pressure 

measurable in the water, which can 

arise from a positive or negative sound 

pressure, during a specified time, for a 

specific frequency range at a specified 

distance from the source, and is 

represented in the same units as the 

RMS sound pressure (ISO, 2017). Along 

with SEL, this metric is used in 

evaluating the potential for permanent 

threshold shift (PTS) and temporary 

threshold shift (TTS) associated with 

impulsive sound sources. 

Sounds are also characterized by their 

temporal components. Continuous 

sounds are those whose sound pressure 

level remains above that of the ambient 

or background sound with negligibly 

small fluctuations in level (ANSI, 2005) 

while intermittent sounds are defined as 

sounds with interrupted levels of low or 

no sound (National Institute for 

Occupational Safety and Health 

(NIOSH), 1998). A key distinction 

between continuous and intermittent 

sound sources is that intermittent 

sounds have a more regular 

(predictable) pattern of bursts of sounds 

and silent periods (i.e., duty cycle), 

which continuous sounds do not. 

Sounds may be either impulsive or 

non-impulsive (defined below). The 

distinction between these two sound 

types is important because they have 

differing potential to cause physical 

effects, particularly with regard to noiseinduced hearing loss (e.g., Ward, 1997 

in Southall et al., 2007). Please see 

NMFS (2018) and Southall et al. (2007, 

2019) for an in-depth discussion of 

these concepts. 

Impulsive sound sources (e.g., 

explosions, gunshots, sonic booms, 

seismic airgun shots, impact pile 

driving) produce signals that are brief 

(typically considered to be less than 1 

second), broadband, atonal transients 

(ANSI, 1986, 2005; NIOSH, 1998) and 

occur either as isolated events or 

repeated in some succession. Impulsive 

sounds are all characterized by a 

relatively rapid rise from ambient 

pressure to a maximal pressure value 

followed by a rapid decay period that 

may include a period of diminishing, 

oscillating maximal and minimal 

pressures, and generally have an 

increased capacity to induce physical 

injury as compared with sounds that 

lack these features. Impulsive sounds 

are intermittent in nature. The duration 

of such sounds, as received at a 

distance, can be greatly extended in a 

highly reverberant environment. 

Non-impulsive sounds can be tonal, 

narrowband, or broadband, brief or 

prolonged, and may be either 

continuous or non-continuous (i.e., 

intermittent) (ANSI, 1995; NIOSH, 

1998). Some of these non-impulsive 

sounds can be transient signals of short 

duration but without the essential 

properties of impulses (e.g., rapid rise 

time). Examples of non-impulsive 

sounds include those produced by 

vessels, aircraft, machinery operations 

such as drilling or dredging, vibratory 

pile driving, and active sonar systems. 

Even in the absence of sound from the 

specified activity, the underwater 

environment is characterized by sounds 

from both natural and anthropogenic 

sound sources. Ambient sound is 

defined as a composite of naturallyoccurring (i.e., non-anthropogenic) 

sound from many sources both near and 

far (ANSI, 1995). Background sound is 

similar but includes all sounds, 

including anthropogenic sounds minus 


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the sound produced by the proposed 

activities (NMFS, 2012, 2016a). The 

sound level of a region is defined by the 

total acoustical energy being generated 

by known and unknown sources. These 

sources may include physical (e.g., 

wind and waves, earthquakes, ice, 

atmospheric sound), biological (e.g., 

sounds produced by marine mammals, 

fish, and invertebrates), and 

anthropogenic (e.g., vessels, dredging, 

construction) sound. A number of 

sources contribute to background and 

ambient sound, including wind and 

waves, which are a main source of 

naturally occurring ambient sound for 

frequencies between 200 Hz and 50 

kilohertz (kHz) (Mitson, 1995). In 

general, background and ambient sound 

levels tend to increase with increasing 

wind speed and wave height. 

Precipitation can become an important 

component of total sound at frequencies 

above 500 Hz, and possibly down to 100 

Hz during quiet times. Marine mammals 

can contribute significantly to 

background and ambient sound levels, 

as can some fish and snapping shrimp. 

The frequency band for biological 

contributions is from approximately 12 

Hz to over 100 kHz. Sources of 

background sound related to human 

activity include transportation (surface 

vessels), dredging and construction, oil 

and gas drilling and production, 

geophysical surveys, sonar, and 

explosions. Vessel noise typically 

dominates the total background sound 

for frequencies between 20 and 300 Hz. 

In general, the frequencies of many 

anthropogenic sounds, particularly 

those produced by construction 

activities, are below 1 kHz (Richardson 

et al., 1995). When sounds at 

frequencies greater than 1 kHz are 

produced, they generally attenuate 

relatively rapidly (Richardson et al., 

1995), particularly above 20 kHz due to 

propagation losses and absorption 

(Urick, 1983). 

Transmission loss (TL) defines the 

degree to which underwater sound has 

spread in space and lost energy after 

having moved through the environment 

and reached a receiver. It is defined by 

the ISO as the reduction in a specified 

level between two specified points that 

are within an underwater acoustic field 

(ISO, 2017). Careful consideration of 

transmission loss and appropriate 

propagation modeling is a crucial step 

in determining the impacts of 

underwater sound, as it helps to define 

the ranges (isopleths) to which impacts 

are expected and depends significantly 

on local environmental parameters such 

as seabed type, water depth 

(bathymetry), and the local speed of 

sound. Geometric spreading laws are 

powerful tools which provide a simple 

means of estimating TL, based on the 

shape of the sound wave front in the 

water column. For a sound source that 

is equally loud in all directions and in 

deep water, the sound field takes the 

form of a sphere, as the sound extends 

in every direction uniformly. In this 

case, the intensity of the sound is spread 

across the surface of the sphere, and 

thus we can relate intensity loss to the 

square of the range (as area = 4*pi*r2). 

This can be expressed logarithmically, 

where TL = 20*Log10(range). This 

situation is known as spherical 

spreading. In shallow water, the sea 

surface and seafloor will bound the 

shape of the sound wave, leading to a 

more cylindrical shape, as the top and 

bottom of the sphere is truncated by the 

largely reflective boundaries. This 

situation is termed cylindrical 

spreading, and is given by TL = 

10*Log10(range) (Urick, 1983). An 

intermediate scenario may be defined by 

the equation TL = 15*Log10(range), and 

is referred to as practical spreading. 

Though these geometric spreading 

scenarios do not capture many often 

important details (scattering, absorption, 

etc.), they offer a reasonable and simple 

approximation of how sound decreases 

in intensity as it is transmitted. In the 

absence of measured data indicating the 

level of transmission loss at a given site 

for a specific activity, NMFS 

recommends practical spreading (i.e., 

TL = 15*Log10(range)) to model acoustic 

propagation for construction activities 

in most nearshore environments. 

The sum of the various natural and 

anthropogenic sound sources at any 

given location and time depends not 

only on the source levels, but also on 

the propagation of sound through the 

environment. Sound propagation is 

dependent on the spatially and 

temporally varying properties of the 

water column and sea floor, and is 

frequency-dependent. As a result of the 

dependence on a large number of 

varying factors, background and 

ambient sound levels can be expected to 

vary widely over both coarse and fine 

spatial and temporal scales. Sound 

levels at a given frequency and location 

can vary by 10 to 20 dB from day to day 

(Richardson et al., 1995). The result is 

that, depending on the source type and 

its intensity, sound from the specified 

activity may be a negligible addition to 

the local environment or could form a 

distinctive signal that may affect marine 

mammals. 

Background underwater noise levels 

in the CTR Project area are both variable 

and relatively high, primarily because of 

extreme tidal activity, elevated sediment 

loads in the water column, periodic 

high winds, the seasonal presence of 

ice, and anthropogenic activities. 

Sources of anthropogenic noise in the 

CTR Project area consist of dredging 

operations, boats, ships, oil and gas 

operations, construction noise, and 

aircraft overflights from JBER and Ted 

Stevens International Airport, all of 

which contribute to high underwater 

noise levels in upper Cook Inlet (e.g., 

Blackwell and Greene, 2002; (Knik Arm 

Bridge and Toll Authority (KABATA), 

2011; Castellote et al., 2018). 

Background sound levels were 

measured at the POA during the PAMP 

2016 Test Pile Program (TPP) in the 

absence of pile driving at two locations 

during a 3-day break in pile installation. 

Median background noise levels, 

measured at a location just offshore of 

the POA SFD and at a second location 

about 1 km offshore, were 117 and 122.2 

dB RMS, respectively (Austin et al., 

2016). NMFS considers the median 

sound levels to be most appropriate 

when considering background noise 

levels for purposes of evaluating the 

potential impacts of the proposed 

project on marine mammals (NMFS, 

2012). By using the median value, 

which is the 50th percentile of the 

measurements, for background noise 

levels, one will be able to eliminate the 

few transient loud identifiable events 

that do not represent the true ambient 

condition of the area. This is relevant 

because during 2 of the 4 days (50 

percent) when background 

measurement data were being collected, 

the USACE was dredging Terminal 3 

(located just north of the AmbientOffshore hydrophone) for 24 hours per 

day with two 1-hour breaks for crew 

change. On the last 2 days of data 

collection, no dredging occurred. 

Therefore, the median provides a better 

representation of background noise 

levels when the CTR project would be 

occurring. During the measurements, 

some typical sound signals were noted, 

such as noise from current flow and the 

passage of vessels. 

With regard to spatial considerations 

of the measurements, the offshore 

location is most applicable to assessing 

background sound during the CTR 

project (NMFS, 2012). The median 

background noise level measured at the 

offshore hydrophone was 122.2 dB 

RMS. The measurement location closer 

to the POA was quieter, with a median 

of 117 dB; however, that hydrophone 

was placed very close to a dock. During 

PCT acoustic monitoring, noise levels in 

Knik Arm absent pile driving were also 

collected (Illingworth & Rodkin (I&R), 

2021a, 2022b)); however, the PCT IHAs 

did not require background noise 


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measurements to be collected in 

adherence with NMFS (2012) 

methodological recommendations. 

Despite this, the noise levels measured 

during the PCT project were not 

significantly different from 122.2 dB 

(I&R, 2021a, 2022b). If additional 

background data are collected in the 

future in this region, NMFS may reevaluate the data to appropriately 

characterize background sound levels in 

Knik Arm. 

Description of Sound Sources for the 

Specified Activities 

In-water construction activities 

associated with the project that have the 

potential to incidentally take marine 

mammals through exposure to sound 

would include impact pile installation 

and vibratory pile installation and 

removal. Impact hammers typically 

operate by repeatedly dropping and/or 

pushing a heavy piston onto a pile to 

drive the pile into the substrate. Sound 

generated by impact hammers is 

impulsive, characterized by rapid rise 

times and high peak levels, a potentially 

injurious combination (Hastings and 

Popper, 2005). Vibratory hammers 

install piles by vibrating them and 

allowing the weight of the hammer to 

push them into the sediment. Vibratory 

hammers typically produce less sound 

(i.e., lower levels) than impact 

hammers. Peak SPLs may be 180 dB or 

greater but are generally 10 to 20 dB 

lower than SPLs generated during 

impact pile driving of the same-sized 

pile (Oestman et al., 2009; California 

Department of Transportation 

(CALTRANS), 2015, 2020). Sounds 

produced by vibratory hammers are 

non-impulsive; the rise time is slower, 

reducing the probability and severity of 

injury, and the sound energy is 

distributed over a greater amount of 

time (Nedwell and Edwards, 2002; 

Carlson et al., 2005). 

The likely or possible impacts of the 

POA’s proposed activities on marine 

mammals could involve both nonacoustic and acoustic stressors. 

Potential non-acoustic stressors could 

result from the physical presence of the 

equipment and personnel; however, 

given there are no known pinniped 

haul-out sites in the vicinity of the CTR 

project site, visual and other nonacoustic stressors would be limited, and 

any impacts to marine mammals are 

expected to primarily be acoustic in 

nature. 

Acoustic Impacts 

The introduction of anthropogenic 

noise into the aquatic environment from 

pile driving is the primary means by 

which marine mammals may be 

harassed from the POA’s specified 

activity. In general, animals exposed to 

natural or anthropogenic sound may 

experience physical and psychological 

effects, ranging in magnitude from none 

to severe (Southall et al., 2007, 2019). 

Exposure to pile driving noise has the 

potential to result in auditory threshold 

shifts and behavioral reactions (e.g., 

avoidance, temporary cessation of 

foraging and vocalizing, changes in dive 

behavior). Exposure to anthropogenic 

noise can also lead to non-observable 

physiological responses, such as an 

increase in stress hormones. Additional 

noise in a marine mammal’s habitat can 

mask acoustic cues used by marine 

mammals to carry out daily functions, 

such as communication and predator 

and prey detection. The effects of pile 

driving noise on marine mammals are 

dependent on several factors, including, 

but not limited to, sound type (e.g., 

impulsive vs. non-impulsive), the 

species, age and sex class (e.g., adult 

male vs. mom with calf), duration of 

exposure, the distance between the pile 

and the animal, received levels, 

behavior at time of exposure, and 

previous history with exposure 

(Wartzok et al., 2004; Southall et al., 

2007). Here, we discuss physical 

auditory effects (threshold shifts) 

followed by behavioral effects and 

potential impacts on habitat. 

NMFS defines a noise-induced 

threshold shift (TS) as a change, usually 

an increase, in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level (NMFS, 2018). The amount of 

threshold shift is customarily expressed 

in dB. A TS can be permanent or 

temporary. As described in NMFS 

(2018, 2024) there are numerous factors 

to consider when examining the 

consequence of TS, including, but not 

limited to, the signal temporal pattern 

(e.g., impulsive or non-impulsive), 

likelihood an individual would be 

exposed for a long enough duration or 

to a high enough level to induce a TS, 

the magnitude of the TS, time to 

recovery (seconds to minutes or hours to 

days), the frequency range of the 

exposure (i.e., spectral content), the 

hearing frequency range of the exposed 

species relative to the signal’s frequency 

spectrum (i.e., how animal uses sound 

within the frequency band of the signal; 

e.g., Kastelein et al., 2014), and the 

overlap between the animal and the 

source (e.g., spatial, temporal, and 

spectral). 

Auditory Injury and Permanent 

Threshold Shift (PTS). NMFS defines 

auditory injury as ‘‘damage to the inner 

ear that can result in destruction of 

tissue . . . which may or may not result 

in PTS’’ (NMFS, 2024). NMFS defines 

PTS as a permanent, irreversible 

increase in the threshold of audibility at 

a specified frequency or portion of an 

individual’s hearing range above a 

previously established reference level 

(NMFS, 2024). PTS does not generally 

affect more than a limited frequency 

range, and an animal that has incurred 

PTS has incurred some level of hearing 

loss at the relevant frequencies; 

typically, animals with PTS are not 

functionally deaf (Au and Hastings, 

2008; Finneran, 2016). Available data 

from humans and other terrestrial 

mammals indicate that a 40–dB 

threshold shift approximates PTS onset 

(see Ward et al., 1958, 1959, 1960; 

Kryter et al., 1966; Miller, 1974; Ahroon 

et al., 1996; Henderson et al., 2008). PTS 

levels for marine mammals are 

estimates, as with the exception of a 

single study unintentionally inducing 

PTS in a harbor seal (Kastak et al., 

2008), there are no empirical data 

measuring PTS in marine mammals 

largely due to the fact that, for various 

ethical reasons, experiments involving 

anthropogenic noise exposure at levels 

inducing PTS are not typically pursued 

or authorized (NMFS, 2018). 

Temporary Threshold Shift (TTS). A 

temporary, reversible increase in the 

threshold of audibility at a specified 

frequency or portion of an individual’s 

hearing range above a previously 

established reference level (NMFS, 

2018). Based on data from marine 

mammal TTS measurements (see 

Southall et al., 2007, 2019), a TTS of 6 

dB is considered the minimum 

threshold shift clearly larger than any 

day-to-day or session-to-session 

variation in a subject’s normal hearing 

ability (Finneran et al., 2000, 2002; 

Schlundt et al., 2000). As described in 

Finneran (2015), marine mammal 

studies have shown the amount of TTS 

increases with SELcum in an accelerating 

fashion: at low exposures with lower 

SELcum, the amount of TTS is typically 

small and the growth curves have 

shallow slopes. At exposures with 

higher SELcum, the growth curves 

become steeper and approach linear 

relationships with the noise SEL. 

Depending on the degree (elevation of 

threshold in dB), duration (i.e., recovery 

time), and frequency range of TTS, and 

the context in which it is experienced, 

TTS can have effects on marine 

mammals ranging from discountable to 

serious (similar to those discussed in 

auditory masking, below). For example, 

a marine mammal may be able to readily 

compensate for a brief, relatively small 

amount of TTS in a non-critical 

frequency range that takes place during 


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a time when the animal is traveling 

through the open ocean, where ambient 

noise is lower and there are not as many 

competing sounds present. 

Alternatively, a larger amount and 

longer duration of TTS sustained during 

time when communication is critical for 

successful mother/calf interactions 

could have more serious impacts. We 

note that reduced hearing sensitivity as 

a simple function of aging has been 

observed in marine mammals, as well as 

humans and other taxa (Southall et al., 

2007), so we can infer that strategies 

exist for coping with this condition to 

some degree, though likely not without 

cost. 

Many studies have examined noiseinduced hearing loss in marine 

mammals (see Finneran (2015) and 

Southall et al. (2019) for summaries). 

TTS is the mildest form of hearing 

impairment that can occur during 

exposure to sound (Kryter, 2013). While 

experiencing TTS, the hearing threshold 

rises, and a sound must be at a higher 

level in order to be heard. In terrestrial 

and marine mammals, TTS can last from 

minutes or hours to days (in cases of 

strong TTS). In many cases, hearing 

sensitivity recovers rapidly after 

exposure to the sound ends. For 

cetaceans, published data on the onset 

of TTS are limited to captive bottlenose 

dolphin (Tursiops truncatus), beluga 

whale, harbor porpoise, and Yangtze 

finless porpoise (Neophocoena 

asiaeorientalis) (Southall et al., 2019). 

For pinnipeds in water, measurements 

of TTS are limited to harbor seals, 

elephant seals (Mirounga angustirostris), 

bearded seals (Erignathus barbatus) and 

California sea lions (Zalophus 

californianus) (Kastak et al., 1999, 2007; 

Kastelein et al., 2019b, 2019c, 2021, 

2022a, 2022b; Reichmuth et al., 2019; 

Sills et al., 2020). TTS was not observed 

in spotted (Phoca largha) and ringed 

(Pusa hispida) seals exposed to single 

airgun impulse sounds at levels 

matching previous predictions of TTS 

onset (Reichmuth et al., 2016). These 

studies examine hearing thresholds 

measured in marine mammals before 

and after exposure to intense or longduration sound exposures. The 

difference between the pre-exposure 

and post-exposure thresholds can be 

used to determine the amount of 

threshold shift at various post-exposure 

times. 

The amount and onset of TTS 

depends on the exposure frequency. 

Sounds at low frequencies, well below 

the region of best sensitivity for a 

species or hearing group, are less 

hazardous than those at higher 

frequencies, near the region of best 

sensitivity (Finneran and Schlundt, 

2013). At low frequencies, onset-TTS 

exposure levels are higher compared to 

those in the region of best sensitivity 

(i.e., a low frequency noise would need 

to be louder to cause TTS onset when 

TTS exposure level is higher), as shown 

for harbor porpoises and harbor seals 

(Kastelein et al., 2019a, 2019c). Note 

that in general, harbor seals and harbor 

porpoises have a lower TTS onset than 

other measured pinniped or cetacean 

species (Finneran, 2015). In addition, 

TTS can accumulate across multiple 

exposures, but the resulting TTS will be 

less than the TTS from a single, 

continuous exposure with the same SEL 

(Mooney et al., 2009; Finneran et al., 

2010; Kastelein et al., 2014, 2015). This 

means that TTS predictions based on 

the total, cumulative SEL will 

overestimate the amount of TTS from 

intermittent exposures, such as sonars 

and impulsive sources. Nachtigall et al. 

(2018) describe measurements of 

hearing sensitivity of multiple 

odontocete species (bottlenose dolphin, 

harbor porpoise, beluga, and false killer 

whale (Pseudorca crassidens)) when a 

relatively loud sound was preceded by 

a warning sound. These captive animals 

were shown to reduce hearing 

sensitivity when warned of an 

impending intense sound. Based on 

these experimental observations of 

captive animals, the authors suggest that 

wild animals may dampen their hearing 

during prolonged exposures or if 

conditioned to anticipate intense 

sounds. Another study showed that 

echolocating animals (including 

odontocetes) might have anatomical 

specializations that might allow for 

conditioned hearing reduction and 

filtering of low-frequency ambient 

noise, including increased stiffness and 

control of middle ear structures and 

placement of inner ear structures 

(Ketten et al., 2021). Data available on 

noise-induced hearing loss for 

mysticetes are currently lacking (NMFS, 

2018). Additionally, the existing marine 

mammal TTS data come from a limited 

number of individuals within these 

species. 

Relationships between TTS and PTS 

thresholds have not been studied in 

marine mammals, and there is no PTS 

data for cetaceans. However, such 

relationships are assumed to be similar 

to those in humans and other terrestrial 

mammals. PTS typically occurs at 

exposure levels at least several dB above 

that inducing mild TTS (e.g., a 40-dB 

threshold shift approximates PTS onset 

(Kryter et al., 1966; Miller, 1974), while 

a 6-dB threshold shift approximates TTS 

onset (Southall et al., 2007, 2019). Based 

on data from terrestrial mammals, a 

precautionary assumption is that the 

PTS thresholds for impulsive sounds 

(such as impact pile driving pulses as 

received close to the source) are at least 

6 dB higher than the TTS threshold on 

a peak-pressure basis, and PTS 

cumulative sound exposure level 

thresholds are 15 to 20 dB higher than 

TTS cumulative sound exposure level 

thresholds (Southall et al., 2007, 2019). 

Given the higher level of sound or 

longer exposure duration necessary to 

cause PTS as compared with TTS, it is 

considerably less likely that PTS could 

occur. 

Behavioral Harassment. Exposure to 

noise also has the potential to 

behaviorally disturb marine mammals to 

a level that rises to the definition of 

harassment under the MMPA. Generally 

speaking, NMFS considers a behavioral 

disturbance that rises to the level of 

harassment under the MMPA a nonminor response—in other words, not 

every response qualifies as behavioral 

disturbance, and for responses that do, 

those of a higher level, or accrued across 

a longer duration, have the potential to 

affect foraging, reproduction, or 

survival. Behavioral disturbance may 

include a variety of effects, including 

subtle changes in behavior (e.g., minor 

or brief avoidance of an area or changes 

in vocalizations), more conspicuous 

changes in similar behavioral activities, 

and more sustained and/or potentially 

severe reactions, such as displacement 

from or abandonment of high-quality 

habitat. Behavioral responses may 

include changing durations of surfacing 

and dives; changing direction and/or 

speed; reducing/increasing vocal 

activities; changing/cessation of certain 

behavioral activities (such as socializing 

or feeding); eliciting a visible startle 

response or aggressive behavior (such as 

tail/fin slapping or jaw clapping); 

avoidance of areas where sound sources 

are located. Pinnipeds may increase 

their haul out time, possibly to avoid inwater disturbance (Thorson and Reyff, 

2006). 

Behavioral responses to sound are 

highly variable and context-specific and 

any reactions depend on numerous 

intrinsic and extrinsic factors (e.g., 

species, state of maturity, experience, 

current activity, reproductive state, 

auditory sensitivity, time of day), as 

well as the interplay between factors 

(e.g., Richardson et al., 1995; Wartzok et 

al., 2004; Southall et al., 2007, 2019; 

Weilgart, 2007; Archer et al., 2010, Erbe 

et al., 2019). Behavioral reactions can 

vary not only among individuals but 

also within an individual, depending on 

previous experience with a sound 

source, context, and numerous other 

factors (Ellison et al., 2012), and can 


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vary depending on characteristics 

associated with the sound source (e.g., 

whether it is moving or stationary, 

number of sources, distance from the 

source). In general, pinnipeds seem 

more tolerant of, or at least habituate 

more quickly to, potentially disturbing 

underwater sound than do cetaceans 

and generally seem to be less responsive 

to exposure to industrial sound than 

most cetaceans. Please see appendices B 

and C of Southall et al. (2007) and 

Gomez et al. (2016) for reviews of 

studies involving marine mammal 

behavioral responses to sound. 

Habituation can occur when an 

animal’s response to a stimulus wanes 

with repeated exposure, usually in the 

absence of unpleasant associated events 

(Wartzok et al., 2004). Animals are most 

likely to habituate to sounds that are 

predictable and unvarying. It is 

important to note that habituation is 

appropriately considered as a 

‘‘progressive reduction in response to 

stimuli that are perceived as neither 

aversive nor beneficial,’’ rather than as, 

more generally, moderation in response 

to human disturbance (Bejder et al., 

2009). The opposite process is 

sensitization, when an unpleasant 

experience leads to subsequent 

responses, often in the form of 

avoidance, at a lower level of exposure. 

As noted above, behavioral state may 

affect the type of response. For example, 

animals that are resting may show 

greater behavioral change in response to 

disturbing sound levels than animals 

that are highly motivated to remain in 

an area for feeding (Richardson et al., 

1995; Wartzok et al., 2004; National 

Research Council (NRC), 2005). 

Controlled experiments with captive 

marine mammals have showed 

pronounced behavioral reactions, 

including avoidance of loud sound 

sources (Ridgway et al., 1997; Finneran 

et al., 2003). Observed responses of wild 

marine mammals to loud pulsed sound 

sources (e.g., seismic airguns) have been 

varied but often consist of avoidance 

behavior or other behavioral changes 

(Richardson et al., 1995; Morton and 

Symonds, 2002; Nowacek et al., 2007). 

Available studies show wide variation 

in response to underwater sound; 

therefore, it is difficult to predict 

specifically how any given sound in a 

particular instance might affect marine 

mammals perceiving the signal (e.g., 

Erbe et al., 2019). If a marine mammal 

does react briefly to an underwater 

sound by changing its behavior or 

moving a small distance, the impacts of 

the change are unlikely to be significant 

to the individual, let alone the stock or 

population. However, if a sound source 

displaces marine mammals from an 

important feeding or breeding area for a 

prolonged period, impacts on 

individuals and populations could be 

significant (e.g., Lusseau and Bejder, 

2007; Weilgart, 2007; NRC, 2005). 

However, there are broad categories of 

potential response, which we describe 

in greater detail here, that include 

alteration of dive behavior, alteration of 

foraging behavior, effects to breathing, 

interference with or alteration of 

vocalization, avoidance, and flight. 

Changes in dive behavior can vary 

widely and may consist of increased or 

decreased dive times and surface 

intervals as well as changes in the rates 

of ascent and descent during a dive (e.g., 

Frankel and Clark, 2000; Costa et al., 

2003; Ng and Leung, 2003; Nowacek et 

al., 2004; Goldbogen et al., 2013a, 

2013b, Blair et al., 2016). Variations in 

dive behavior may reflect interruptions 

in biologically significant activities (e.g., 

foraging) or they may be of little 

biological significance. The impact of an 

alteration to dive behavior resulting 

from an acoustic exposure depends on 

what the animal is doing at the time of 

the exposure and the type and 

magnitude of the response. 

Disruption of feeding behavior can be 

difficult to correlate with anthropogenic 

sound exposure, so it is usually inferred 

by observed displacement from known 

foraging areas, the appearance of 

secondary indicators (e.g., bubble nets 

or sediment plumes) or changes in dive 

behavior. However, acoustic and 

movement bio-logging tools have been 

used in some cases, to infer responses 

of feeding to anthropogenic noise. For 

example, Blair et al. (2016) reported 

significant effects on humpback whale 

foraging behavior in Stellwagen Bank in 

response to ship noise including slower 

descent rates, and fewer side-rolling 

events per dive with increasing ship 

nose. In addition, Wisniewska et al. 

(2018) reported that tagged harbor 

porpoises demonstrated fewer prey 

capture attempts when encountering 

occasional high-noise levels resulting 

from vessel noise as well as more 

vigorous fluking, interrupted foraging, 

and cessation of echolocation signals 

observed in response to some high-noise 

vessel passes. 

In response to playbacks of vibratory 

pile driving sounds, captive bottlenose 

dolphins showed changes in target 

detection and number of clicks used for 

a trained echolocation task (Branstetter 

et al. 2018). Similarly, harbor porpoises 

trained to collect fish during playback of 

impact pile driving sounds also showed 

potential changes in behavior and task 

success, though individual differences 

were prevalent (Kastelein et al. 2019d). 

As for other types of behavioral 

response, the frequency, duration, and 

temporal pattern of signal presentation, 

as well as differences in species 

sensitivity, are likely contributing 

factors to differences in response in any 

given circumstance (e.g., Croll et al., 

2001; Nowacek et al., 2004; Madsen et 

al., 2006; Yazvenko et al., 2007). A 

determination of whether foraging 

disruptions incur fitness consequences 

would require information on or 

estimates of the energetic requirements 

of the affected individuals and the 

relationships among prey availability, 

foraging effort and success, and the life 

history stage(s) of the animal. 

Variations in respiration naturally 

vary with different behaviors and 

alterations to breathing rate as a 

function of acoustic exposure can be 

expected to co-occur with other 

behavioral reactions, such as a flight 

response or an alteration in diving. 

However, respiration rates in and of 

themselves may be representative of 

annoyance or an acute stress response. 

Various studies have shown that 

respiration rates may either be 

unaffected or could increase, depending 

on the species and signal characteristics, 

again highlighting the importance in 

understanding species differences in the 

tolerance of underwater noise when 

determining the potential for impacts 

resulting from anthropogenic sound 

exposure (e.g., Kastelein et al., 2001, 

2005, 2006; Gailey et al., 2007). For 

example, harbor porpoise’ respiration 

rate increased in response to pile 

driving sounds at and above a received 

broadband SPL of 136 dB (zero-peak 

SPL: 151 dB re 1 mPa; SEL of a single 

strike: 127 dB re 1 mPa2-s) (Kastelein et 

al., 2013). 

Avoidance is the displacement of an 

individual from an area or migration 

path as a result of the presence of a 

sound or other stressors, and is one of 

the most obvious manifestations of 

disturbance in marine mammals 

(Richardson et al., 1995). For example, 

gray whales are known to change 

direction—deflecting from customary 

migratory paths—in order to avoid noise 

from seismic surveys (Malme et al., 

1984). In response to construction noise 

from offshore wind farms, harbor 

porpoises and harbor seals have 

demonstrated avoidance on the scale of 

hours to weeks (Brandt et al., 2018; 

Russell et al., 2016). Avoidance may be 

short-term, with animals returning to 

the area once the noise has ceased (e.g., 

Bowles et al., 1994; Goold, 1996; Stone 

et al., 2000; Morton and Symonds, 2002; 

Gailey et al., 2007). Longer-term 

displacement is possible, however, 

which may lead to changes in 

abundance or distribution patterns of 


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the affected species in the affected 

region if habituation to the presence of 

the sound does not occur (e.g., 

Blackwell et al., 2004; Bejder et al., 

2006; Teilmann et al., 2006). 

A flight response is a dramatic change 

in normal movement to a directed and 

rapid movement away from the 

perceived location of a sound source. 

The flight response differs from other 

avoidance responses in the intensity of 

the response (e.g., directed movement, 

rate of travel). Relatively little 

information on flight responses of 

marine mammals to anthropogenic 

signals exist, although observations of 

flight responses to the presence of 

predators have occurred (Connor and 

Heithaus, 1996; Bowers et al., 2018). 

The result of a flight response could 

range from brief, temporary exertion and 

displacement from the area where the 

signal provokes flight to, in extreme 

cases, marine mammal strandings 

(England et al., 2001). However, it 

should be noted that response to a 

perceived predator does not necessarily 

invoke flight (Ford and Reeves, 2008), 

and whether individuals are solitary or 

in groups may influence the response. 

Behavioral disturbance can also 

impact marine mammals in more subtle 

ways. Increased vigilance may result in 

costs related to diversion of focus and 

attention (i.e., when a response consists 

of increased vigilance, it may come at 

the cost of decreased attention to other 

critical behaviors such as foraging or 

resting). These effects have generally not 

been demonstrated for marine 

mammals, but studies involving fishes 

and terrestrial animals have shown that 

increased vigilance may substantially 

reduce feeding rates (e.g., Beauchamp 

and Livoreil, 1997; Fritz et al., 2002; 

Purser and Radford, 2011). In addition, 

chronic disturbance can cause 

population declines through reduction 

of fitness (e.g., decline in body 

condition) and subsequent reduction in 

reproductive success, survival, or both 

(e.g., Harrington and Veitch, 1992; Daan 

et al., 1996; Bradshaw et al., 1998). 

However, Ridgway et al. (2006) reported 

that increased vigilance in bottlenose 

dolphins exposed to sound over a 5-day 

period did not cause any sleep 

deprivation or stress effects. 

Many animals perform vital functions, 

such as feeding, resting, traveling, and 

socializing, on a diel cycle (24-hour 

cycle). Disruption of such functions 

resulting from reactions to stressors 

such as sound exposure are more likely 

to be significant if they last more than 

one diel cycle or recur on subsequent 

days (Southall et al., 2007). 

Consequently, a behavioral response 

lasting less than 1 day and not recurring 

on subsequent days is not considered 

particularly severe unless it could 

directly affect reproduction or survival 

(Southall et al., 2007). Note that there is 

a difference between multi-day 

substantive (i.e., meaningful) behavioral 

reactions and multi-day anthropogenic 

activities. For example, just because an 

activity lasts for multiple days does not 

necessarily mean that individual 

animals are either exposed to activityrelated stressors for multiple days or, 

further, exposed in a manner resulting 

in sustained multi-day substantive 

behavioral responses. 

Behavioral Reactions Observed at the 

POA. Specific to recent construction at 

the POA, behavioral reactions to pile 

driving have not been reported in nonCIBW species. During POA’s PCT 

construction, 81 harbor seals were 

observed within estimated Level B 

harassment zones associated with 

vibratory and impact installation and 

removal of 36-in (61-cm) and 144-in 

(366-cm) piles, and 5 harbor seals were 

observed within estimated Level A 

harassment zones during the installation 

of 144-in (366-cm) piles. No observable 

behavioral reactions were observed in 

any of these seals (61N Environmental, 

2021, 2022a). One harbor porpoise was 

observed within the estimated Level B 

harassment zone during vibratory 

driving of a 36-in (61-cm) pile in May 

2021. The animal was traveling at a 

moderate pace. No observable reactions 

to pile driving were noted by the PSOs. 

Another harbor porpoise near the border 

of (and may have been within) the 

estimated Level B harassment zone 

during the impact installation of 36-in 

(61-cm) piles in June 2021, but PSOs did 

not record any behavioral responses of 

this individual to the pile driving 

activities. Similarly 13 harbor seals 

observed within estimated Level B 

harassment zones associated with pile 

driving 36-in (61-cm) piles during 

POA’s SFD construction did not exhibit 

observable behavioral reactions (61N 

Environmental, 2022b). 

Specific to CIBWs, several years of 

marine mammal monitoring data 

demonstrate behavioral responses to 

pile driving at the POA. Previous pile 

driving activities at the POA include the 

installation and removal of sheet piles, 

the vibratory and impact installation of 

24-in (61-cm), 36-in (91-cm), 48-in (122- 

cm), and 144-in (366-cm) pipe piles, and 

the vibratory installation of 72-in (182- 

cm) air bubble casings. 

Kendall and Cornick (2015) provide a 

comprehensive overview of 4 years of 

scientific marine mammal monitoring 

conducted before (2005–2006) and 

during the POA’s MTRP (2008–2009). 

These were observations made by 

biologists at Alaska Pacific University, 

funded by the POA and other groups but 

independent of the POA’s required 

monitoring for pile driving activities 

(i.e., not construction based PSOs). The 

authors investigated CIBW behavior 

before and during pile driving activity at 

the POA. Sighting rates, mean sighting 

duration, behavior, mean group size, 

group composition, and group formation 

were compared between the two 

periods. A total of about 2,329 hours of 

sampling effort was completed across 

349 days from 2005 to 2009. Overall, 

687 whales in 177 groups were 

documented during the 69 days that 

whales were sighted. A total of 353 and 

1,663 hours of pile driving took place in 

2008 and 2009, respectively. There was 

no relationship between monthly CIBW 

sighting rates and monthly pile driving 

rates (r = 0.19, p = 0.37). Sighting rates 

before (n = 12; 0.06 ± 0.01) and during 

(n = 13; 0.01 ± 0.03) pile driving were 

not significantly different. However, 

sighting duration of CIBWs decreased 

significantly during pile driving (39 ± 6 

min before and 18 ± 3 min during). 

There were also significant differences 

in behavior before versus during pile 

driving. CIBWs primarily traveled 

through the study area both before and 

during pile driving; however, traveling 

increased relative to other behaviors 

during pile driving. Documentation of 

milling was observed on 21 occasions 

during pile driving. Mean group size 

decreased during pile driving; however, 

this difference was not statistically 

significant. In addition, group 

composition was significantly different 

before and during pile driving, with 

more white (i.e., likely older) animals 

being present during pile driving 

(Kendall and Cornick, 2015). CIBWs 

were primarily observed densely packed 

before and during pile driving; however, 

the number of densely packed groups 

increased by approximately 67 percent 

during pile driving. There were also 

significant increases in the number of 

dispersed groups (approximately 81 

percent) and lone white whales 

(approximately 60 percent) present 

during pile driving than before pile 

driving (Kendall and Cornick, 2015). 

During PCT and SFD construction 

monitoring, behaviors of CIBWs groups 

were compared by month and by 

construction activity (61N 

Environmental, 2021, 2022a, 2022b). 

Little variability was evident in the 

behaviors recorded from month to 

month or among sightings that 

coincided with in-water pile installation 

and removal and those that did not (61N 

Environmental, 2021, 2022a). Definitive 

behavioral reactions to in-water pile 


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driving or avoidance behaviors were not 

documented; however, potential 

reactions (where a group reversed its 

trajectory shortly after the start of inwater pile driving occurred; a group 

reversed its trajectory as it got closer to 

the sound source during active in-water 

pile driving; or upon an initial sighting, 

a group was already moving away from 

in-water pile driving, raising the 

possibility that it had been moving 

towards, but was only sighted after they 

turned away) and instances where 

CIBWs moved toward active in-water 

pile driving were recorded. During these 

instances, impact driving appeared to 

cause potential behavioral reactions 

more readily than vibratory hammering 

(61N Environmental, 2021, 2022a, 

2022b). One minor difference 

documented during PCT construction 

was a slightly higher incidence of 

milling behavior and diving during the 

periods of no pile driving and slightly 

higher rates of traveling behavior during 

periods when potential CIBW 

behavioral reactions to pile driving, as 

described above, were recorded (61N 

Environmental, 2021, 2022a). Note, 

narratives of each CIBW reaction can be 

found in the appendices of the POA’s 

final monitoring reports (61N 

Environmental, 2021, 2022a, 2022b). 

Acoustically, Saxon-Kendall et al. 

(2013) recorded echolocation clicks 

(which can be indicative of feeding 

behavior) during the MTR Project at the 

POA both while pile driving was 

occurring and when it was not. This 

indicates that while feeding is not a 

predominant behavior that PSOs 

visually observed in CIBWs sighted near 

the POA (61N Environmental, 2021, 

2022a, 2022b, 2022c; Easley-Appleyard 

and Leonard, 2022) CIBWs can and still 

exhibit feeding behaviors during pile 

driving activities. In addition, Castellote 

et al. (2020) found low echolocation 

detection rates in lower Knik Arm (i.e., 

Six Mile, Port MacKenzie, and Cairn 

Point) and suggested that CIBWs moved 

through that area relatively quickly 

when entering or exiting the Arm. No 

whistles or noisy vocalizations were 

recorded during the MTRP construction 

activities; however, it is possible that 

persistent noise associated with 

construction activity at the MTR project 

masked beluga vocalizations and or that 

CIBWs did not use these communicative 

signals when they were near the MTR 

Project (Saxon-Kendall et al., 2013). 

Recently, McHuron et al. (2023) 

developed a model to predict general 

patterns related to the movement and 

foraging decisions of pregnant CIBWs in 

Cook Inlet. They found that the effects 

of disturbance from human activities, 

such as pile driving activities occurring 

at the POA assuming no mitigation 

measures, are inextricably linked with 

prey availability. If prey are abundant 

during the summer and early fall and 

prey during winter is above some 

critical threshold, pregnant CIBWs can 

likely cope with intermittent 

disruptions, such as those produced by 

pile driving at the POA (McHuron et al., 

2023). However, they stress that more 

information needs to be acquired 

regarding CIBW prey and CIBW body 

condition, specifically in their critical 

habitat, to better understand possible 

behavioral responses to disturbance. 

Stress responses. An animal’s 

perception of a threat may be sufficient 

to trigger stress responses consisting of 

some combination of behavioral 

responses, autonomic nervous system 

responses, neuroendocrine responses, or 

immune responses (e.g., Selye, 1950; 

Moberg, 2000). In many cases, an 

animal’s first and sometimes most 

economical (in terms of energetic costs) 

response is behavioral avoidance of the 

potential stressor. Autonomic nervous 

system responses to stress typically 

involve changes in heart rate, blood 

pressure, and gastrointestinal activity. 

These responses have a relatively short 

duration and may or may not have a 

significant long-term effect on an 

animal’s fitness. 

Neuroendocrine stress responses often 

involve the hypothalamus-pituitaryadrenal system. Virtually all 

neuroendocrine functions that are 

affected by stress—including immune 

competence, reproduction, metabolism, 

and behavior—are regulated by pituitary 

hormones. Stress-induced changes in 

the secretion of pituitary hormones have 

been implicated in failed reproduction, 

altered metabolism, reduced immune 

competence, and behavioral disturbance 

(e.g., Moberg, 1987; Blecha, 2000). 

Increases in the circulation of 

glucocorticoids are also equated with 

stress (Romano et al., 2004). 

The primary distinction between 

stress (which is adaptive and does not 

normally place an animal at risk) and 

‘‘distress’’ is the cost of the response. 

During a stress response, an animal uses 

glycogen stores that can be quickly 

replenished once the stress is alleviated. 

In such circumstances, the cost of the 

stress response would not pose serious 

fitness consequences. However, when 

an animal does not have sufficient 

energy reserves to satisfy the energetic 

costs of a stress response, energy 

resources must be diverted from other 

functions. This state of distress will last 

until the animal replenishes its 

energetic reserves sufficient to restore 

normal function. 

Relationships between these 

physiological mechanisms, animal 

behavior, and the costs of stress 

responses are well-studied through 

controlled experiments and for both 

laboratory and free-ranging animals 

(e.g., Holberton et al., 1996; Hood et al., 

1998; Jessop et al., 2003; Krausman et 

al., 2004; Lankford et al., 2005). Stress 

responses due to exposure to 

anthropogenic sounds or other stressors 

and their effects on marine mammals 

have also been reviewed (Fair and 

Becker, 2000; Romano et al., 2002b) 

and, more rarely, studied in wild 

populations (e.g., Romano et al., 2002a). 

For example, Rolland et al. (2012) found 

that noise reduction from reduced ship 

traffic in the Bay of Fundy was 

associated with decreased stress in 

North Atlantic right whales. In addition, 

Lemos et al. (2022) observed a 

correlation between higher levels of 

fecal glucocorticoid metabolite 

concentrations (indicative of a stress 

response) and vessel traffic in gray 

whales. These and other studies lead to 

a reasonable expectation that some 

marine mammals will experience 

physiological stress responses upon 

exposure to acoustic stressors and that 

it is possible that some of these would 

be classified as ‘‘distress.’’ In addition, 

any animal experiencing TTS would 

likely also experience stress responses 

(NRC, 2005), however distress is an 

unlikely result of this project based on 

observations of marine mammals during 

previous, similar construction projects. 

Norman (2011) reviewed 

environmental and anthropogenic 

stressors for CIBWs. Lyamin et al. (2011) 

determined that the heart rate of a 

beluga whale increases in response to 

noise, depending on the frequency and 

intensity. Acceleration of heart rate in 

the beluga whale is the first component 

of the ‘‘acoustic startle response.’’ 

Romano et al. (2004) demonstrated that 

captive beluga whales exposed to highlevel impulsive sounds (i.e., seismic 

airgun and/or single pure tones up to 

201 dB RMS) resembling sonar pings 

showed increased stress hormone levels 

of norepinephrine, epinephrine, and 

dopamine when TTS was reached. 

Thomas et al. (1990) exposed beluga 

whales to playbacks of an oil-drilling 

platform in operation (‘‘Sedco 708,’’ 40 

Hz–20 kHz; source level 153 dB). 

Ambient SPL at ambient conditions in 

the pool before playbacks was 106 dB 

and 134 to 137 dB RMS during 

playbacks at the monitoring hydrophone 

across the pool. All cell and platelet 

counts and 21 different blood 

chemicals, including epinephrine and 

norepinephrine, were within normal 


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limits throughout baseline and playback 

periods, and stress response hormone 

levels did not increase immediately 

after playbacks. The difference between 

the Romano et al. (2004) and Thomas et 

al. (1990) studies could be the 

differences in the type of sound (seismic 

airgun and/or tone versus oil drilling), 

the intensity and duration of the sound, 

the individual’s response, and the 

surrounding circumstances of the 

individual’s environment. The 

construction sounds in the Thomas et 

al. (1990) study would be more similar 

to those of pile installation than those 

in the study investigating stress 

response to water guns and pure tones. 

Therefore, no more than short-term, 

low-level hormonal stress responses, if 

any, of beluga whales or other marine 

mammals are expected as a result of 

exposure to in-water pile installation 

and removal during the CTR project. 

Auditory Masking. Since many marine 

mammals rely on sound to find prey, 

moderate social interactions, and 

facilitate mating (Tyack, 2008), noise 

from anthropogenic sound sources can 

interfere with these functions but only 

if the noise spectrum overlaps with the 

hearing sensitivity of the receiving 

marine mammal (Southall et al., 2007; 

Clark et al., 2009; Hatch et al., 2012). 

Chronic exposure to excessive, though 

not high-intensity, noise could cause 

masking at particular frequencies for 

marine mammals that utilize sound for 

vital biological functions (Clark et al., 

2009). Acoustic masking is when other 

noises such as from human sources 

interfere with an animal’s ability to 

detect, recognize, or discriminate 

between acoustic signals of interest (e.g., 

those used for intraspecific 

communication and social interactions, 

prey detection, predator avoidance, 

navigation) (Richardson et al., 1995; 

Erbe et al., 2016). Therefore, under 

certain circumstances, marine mammals 

whose acoustical sensors or 

environment are being severely masked 

could also be impaired from maximizing 

their performance fitness in survival 

and reproduction. The ability of a noise 

source to mask biologically important 

sounds depends on the characteristics of 

both the noise source and the signal of 

interest (e.g., signal-to-noise ratio, 

temporal variability, direction), in 

relation to each other and to an animal’s 

hearing abilities (e.g., sensitivity, 

frequency range, critical ratios, 

frequency discrimination, directional 

discrimination, age or TTS hearing loss), 

and existing ambient noise and 

propagation conditions (Hotchkin and 

Parks, 2013). 

Marine mammals vocalize for 

different purposes and across multiple 

modes, such as whistling, echolocation 

click production, calling, and singing. 

Changes in vocalization behavior in 

response to anthropogenic noise can 

occur for any of these modes and may 

result from a need to compete with an 

increase in background noise or may 

reflect increased vigilance or a startle 

response. For example, in the presence 

of potentially masking signals, 

humpback whales and killer whales 

have been observed to increase the 

length of their songs (Miller et al., 2000; 

Fristrup et al., 2003) or vocalizations 

(Foote et al., 2004), respectively, while 

North Atlantic right whales (Eubalaena 

glacialis) have been observed to shift the 

frequency content of their calls upward 

while reducing the rate of calling in 

areas of increased anthropogenic noise 

(Parks et al., 2007). Fin whales have also 

been documented lowering the 

bandwidth, peak frequency, and center 

frequency of their vocalizations under 

increased levels of background noise 

from large vessels (Castellote et al. 

2012). Other alterations to 

communication signals have also been 

observed. For example, gray whales, in 

response to playback experiments 

exposing them to vessel noise, have 

been observed increasing their 

vocalization rate and producing louder 

signals at times of increased outboard 

engine noise (Dahlheim and Castellote, 

2016). Alternatively, animals may cease 

sound production during production of 

aversive signals (Bowles et al., 1994). 

Under certain circumstances, marine 

mammals experiencing significant 

masking could also be impaired from 

maximizing their performance fitness in 

survival and reproduction. Therefore, 

when the coincident (masking) sound is 

human-made, it may be considered 

harassment when disrupting or altering 

critical behaviors. It is important to 

distinguish TTS and PTS, which persist 

after the sound exposure, from masking, 

which occurs during the sound 

exposure. Because masking (without 

resulting in TS) is not associated with 

abnormal physiological function, it is 

not considered a physiological effect but 

rather, a potential behavioral effect 

(though not necessarily one that would 

be associated with harassment). 

The frequency range of the potentially 

masking sound is important in 

determining any potential behavioral 

impacts. For example, low-frequency 

signals may have less effect on highfrequency echolocation sounds 

produced by odontocetes but are more 

likely to affect detection of mysticete 

communication calls and other 

potentially important natural sounds 

such as those produced by surf and 

some prey species. The masking of 

communication signals by 

anthropogenic noise may be considered 

as a reduction in the communication 

space of animals (e.g., Clark et al., 2009) 

and may result in energetic or other 

costs as animals change their 

vocalization behavior (e.g., Miller et al., 

2000; Foote et al., 2004; Parks et al., 

2007; Di Iorio and Clark, 2010; Holt et 

al., 2009). Masking can be reduced in 

situations where the signal and noise 

come from different directions 

(Richardson et al., 1995), through 

amplitude modulation of the signal, or 

through other compensatory behaviors 

(Hotchkin and Parks, 2013). Masking 

can be tested directly in captive species 

(e.g., Erbe, 2008), but in wild 

populations, it must be either modeled 

or inferred from evidence of masking 

compensation. There are few studies 

addressing real-world masking sounds 

likely to be experienced by marine 

mammals in the wild (e.g., Branstetter et 

al., 2013). 

Marine mammals at or near the 

proposed CTR project site may be 

exposed to anthropogenic noise, which 

may be a source of masking. 

Vocalization changes may result from a 

need to compete with an increase in 

background noise and include 

increasing the source level, modifying 

the frequency, increasing the call 

repetition rate of vocalizations, or 

ceasing to vocalize in the presence of 

increased noise (Hotchkin and Parks, 

2013). For example, in response to loud 

noise, beluga whales may shift the 

frequency of their echolocation clicks 

and communication signals, reduce 

their overall calling rates, and or 

increase the emission of certain call 

signals to prevent masking by 

anthropogenic noise (Lessage et al., 

1999; Tyack, 2000; Eickmeier and 

Vallarta, 2022). 

Masking occurs in the frequency band 

or bands that animals utilize and is 

more likely to occur in the presence of 

broadband, relatively continuous noise 

sources such as vibratory pile driving. 

Energy distribution of pile driving 

covers a broad frequency spectrum, and 

sound from pile driving would be 

within the audible range of pinnipeds 

and cetaceans present in the proposed 

action area. While some construction 

during the POA’s activities may mask 

some acoustic signals that are relevant 

to the daily behavior of marine 

mammals, the short-term duration and 

limited areas affected make it very 

unlikely that the fitness of individual 

marine mammals would be impacted. 

Airborne Acoustic Effects. Pinnipeds 

that occur near the project site could be 

exposed to airborne sounds associated 

with construction activities that have 


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the potential to cause behavioral 

harassment, depending on their distance 

from these activities. Airborne noise 

would primarily be an issue for 

pinnipeds that are swimming or hauled 

out near the project site within the range 

of noise levels elevated above airborne 

acoustic harassment criteria. Although 

pinnipeds are known to haul-out 

regularly on man-made objects, we 

believe that incidents of take resulting 

solely from airborne sound are unlikely 

given there are no known pinniped 

haulout or pupping sites within the 

vicinity of the proposed project area; the 

nearest known pinniped haulout is 

located a minimum of 24 km southsouthwest of Anchorage for harbor seals. 

Cetaceans are not expected to be 

exposed to airborne sounds that would 

result in harassment as defined under 

the MMPA. 

We recognize that pinnipeds in the 

water could be exposed to airborne 

sound that may result in behavioral 

harassment when looking with their 

heads above water. Most likely, airborne 

sound would cause behavioral 

responses similar to those discussed 

above in relation to underwater sound. 

For instance, anthropogenic sound 

could cause hauled-out pinnipeds to 

exhibit changes in their normal 

behavior, such as reduction in 

vocalizations or cause them to 

temporarily abandon the area and move 

further from the source. However, these 

animals would previously have been 

‘taken’ because of exposure to 

underwater sound above the behavioral 

harassment thresholds, which are in all 

cases larger than those associated with 

airborne sound. Thus, the behavioral 

harassment of these animals is already 

accounted for in these estimates of 

potential take. Therefore, we do not 

believe that authorization of incidental 

take resulting from airborne sound for 

pinnipeds is warranted, and airborne 

sound is not discussed further here. 

Potential Effects on Marine Mammal 

Habitat 

The proposed project would occur 

mostly within the same footprint as 

existing marine infrastructure; the new 

T1 and T2 would extend approximately 

140 ft (47-m) seaward of the existing 

terminals. The nearshore and intertidal 

habitat where the proposed project will 

occur is an area of relatively high 

marine vessel traffic. Temporary, 

intermittent habitat alteration may 

result from increased noise levels 

during the proposed construction 

activities. Noise from impact and 

vibratory pile driving may extend across 

Knik Arm, and affect areas outside of 

the area around POA excluded from 

designated CIBW Critical Habitat. 

However, increased noise levels will 

only be present during construction 

activities and will cease when pile 

driving ends. Pile driving is not 

expected on all days during the 

construction season (April–November) 

and is not expected at all during the 

months of December–March. Noise 

exposure is, therefore, expected to be 

temporary and intermittent with long 

periods of typical background noise 

levels on a daily and seasonal scale. 

Effects to CIBW critical habitat are, 

therefore, considered to be nonsignificant. Effects on prey species will 

be limited in time and space. The longterm impact on marine mammal habitat 

associated with CTR would be a small 

permanent decrease in low-quality 

potential habitat because of the 

expanded footprint of the new cargo 

terminals T1 and T2. Installation and 

removal of in-water piles would be 

temporary and intermittent, and the 

increased footprint of the facilities 

would destroy only a small amount of 

low-quality habitat, which currently 

experiences high levels of 

anthropogenic activity. 

Water quality—Temporary and 

localized reduction in water quality 

would occur as a result of in-water 

construction activities. Most of this 

effect would occur during the 

installation and removal of piles when 

bottom sediments are disturbed. The 

installation and removal of piles would 

disturb bottom sediments and may 

cause a temporary increase in 

suspended sediment in the project area. 

During pile removal, sediment attached 

to the pile moves vertically through the 

water column until gravitational forces 

cause it to slough off under its own 

weight. The small resulting sediment 

plume is expected to settle out of the 

water column within a few hours. 

Studies of the effects of turbid water on 

fish (marine mammal prey) suggest that 

concentrations of suspended sediment 

can reach thousands of milligrams per 

liter before an acute toxic reaction is 

expected (Burton, 1993). 

Effects to turbidity and sedimentation 

are expected to be short-term, minor, 

and localized. Since the currents are so 

strong in the area, following the 

completion of sediment-disturbing 

activities, suspended sediments in the 

water column should dissipate and 

quickly return to background levels in 

all construction scenarios. Turbidity 

within the water column has the 

potential to reduce the level of oxygen 

in the water and irritate the gills of prey 

fish species in the proposed project 

area. However, turbidity plumes 

associated with the project would be 

temporary and localized, and fish in the 

proposed project area would be able to 

move away from and avoid the areas 

where plumes may occur. Thus, it is 

expected that the impacts on prey fish 

species from turbidity and therefore, on 

marine mammals, would be minimal 

and temporary. In general, the area 

likely impacted by the proposed 

construction activities is relatively small 

compared to the available marine 

mammal habitat in Knik Arm, and does 

not include any areas of particular 

importance. 

Potential Effects on Prey. Sound may 

affect marine mammals through impacts 

on the abundance, behavior, or 

distribution of prey species (e.g., 

crustaceans, cephalopods, fishes, 

zooplankton). Marine mammal prey 

varies by species, season, and location 

and, for some, is not well documented. 

Studies regarding the effects of noise on 

known marine mammal prey are 

described here. 

Fishes utilize the soundscape and 

components of sound in their 

environment to perform important 

functions such as foraging, predator 

avoidance, mating, and spawning (e.g., 

Zelick et al., 1999; Fay, 2009). 

Depending on their hearing anatomy 

and peripheral sensory structures, 

which vary among species, fishes hear 

sounds using pressure and particle 

motion sensitivity capabilities and 

detect the motion of surrounding water 

(Fay et al., 2008). The potential effects 

of noise on fishes depends on the 

overlapping frequency range, distance 

from the sound source, water depth of 

exposure, and species-specific hearing 

sensitivity, anatomy, and physiology. 

Key impacts to fishes may include 

behavioral responses, hearing damage, 

barotrauma (pressure-related injuries), 

and mortality. 

Fish react to sounds that are 

especially high amplitude and/or 

intermittent at low frequencies. Short 

duration, sharp sounds can cause overt 

or subtle changes in fish behavior and 

local distribution. The reaction of fish to 

noise depends on the physiological state 

of the fish, past exposures, motivation 

(e.g., feeding, spawning, migration), and 

other environmental factors. Hastings 

and Popper (2005) identified several 

studies that suggest fish may relocate to 

avoid certain areas of sound energy. 

Additional studies have documented 

effects of pile driving on fishes (e.g. 

Scholik and Yan, 2001, 2002; Popper 

and Hastings, 2009). Several studies 

have demonstrated that impulsive 

sounds might affect the distribution and 

behavior of some fishes, potentially 

impacting foraging opportunities or 

increasing energetic costs (e.g., Fewtrell 


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and McCauley, 2012; Pearson et al., 

1992; Skalski et al., 1992; Santulli et al., 

1999; Paxton et al., 2017). However, 

some studies have shown no or slight 

reaction to impulse sounds (e.g., Pen ̃ a et 

al., 2013; Wardle et al., 2001; Jorgenson 

and Gyselman, 2009; Cott et al., 2012). 

More commonly, though, the impacts of 

noise on fishes are temporary. 

During the POA’s MTRP, the effects of 

impact and vibratory installation of 30- 

in (76-cm) steel sheet piles at the POA 

on 133 caged juvenile coho salmon in 

Knik Arm were studied (Hart Crowser 

Incorporated et al., 2009; Houghton et 

al., 2010). Acute or delayed mortalities 

or behavioral abnormalities were not 

observed in any of the coho salmon. 

Furthermore, results indicated that the 

pile driving had no adverse effect on 

feeding ability or the ability of the fish 

to respond normally to threatening 

stimuli (Hart Crowser Incorporated et 

al., 2009; Houghton et al., 2010). 

SPLs of sufficient strength have been 

known to cause injury to fishes and fish 

mortality (summarized in Popper et al., 

2014). However, in most fish species, 

hair cells in the ear continuously 

regenerate and loss of auditory function 

likely is restored when damaged cells 

are replaced with new cells. Halvorsen 

et al. (2012b) showed that a TTS of 4 to 

6 dB was recoverable within 24 hours 

for one species. Impacts would be most 

severe when the individual fish is close 

to the source and when the duration of 

exposure is long. Injury caused by 

barotrauma can range from slight to 

severe, can cause death, and is most 

likely for fish with swim bladders. 

Barotrauma injuries have been 

documented during controlled exposure 

to impact pile driving (Halvorsen et al., 

2012a; Casper et al., 2013, 2017). 

Fish populations in the proposed 

project area that serve as marine 

mammal prey could be temporarily 

affected by noise from pile installation 

and removal. The frequency range in 

which fishes generally perceive 

underwater sounds is 50 to 2,000 Hz, 

with peak sensitivities below 800 Hz 

(Popper and Hastings, 2009). Fish 

behavior or distribution may change, 

especially with strong and/or 

intermittent sounds that could harm 

fishes. High underwater SPLs have been 

documented to alter behavior, cause 

hearing loss, and injure or kill 

individual fish by causing serious 

internal injury (Hastings and Popper, 

2005). 

Essential Fish Habitat (EFH) has been 

designated in the estuarine and marine 

waters in the vicinity of the proposed 

project area for all five species of 

salmon (i.e., chum salmon, pink salmon, 

coho salmon, sockeye salmon, and 

Chinook salmon; North Pacific Fishery 

Management Council (NPFMC), 2020, 

2021), which are common prey of 

marine mammals, as well as for other 

species. (NPFMC, 2020). However, there 

are no designated habitat areas of 

particular concern in the vicinity of the 

Port, and therefore, adverse effects on 

EFH in this area are not expected. 

The greatest potential impact to fishes 

during construction would occur during 

impact pile installation. Impact piling 

would occur over 1 to 3 hours on any 

given day across the construction 

season, with significant breaks between 

piles due to repositioning of the crane, 

installation and removal of temporary 

piles, and other construction 

sequencing. Additionally, impact 

driving of 72-in permanent piles would 

be mitigated with the use of a bubble 

curtain (see Proposed Mitigation section 

for full details) in all months of 

construction for piles driven in water 

greater than 3-m deep. Unattenuated 

impact driving in shallow water would 

be minimized as much as feasible by 

timing installation to occur during 

periods of low tide, when the pilings are 

out of water (‘‘in the dry’’). In-water 

construction activities would only occur 

during daylight hours, allowing fish to 

forage and transit the project area in the 

evening. Vibratory pile driving would 

possibly elicit behavioral reactions from 

fishes, such as temporary avoidance of 

the area, but is unlikely to cause injuries 

to fishes or have persistent effects on 

local fish populations. Construction also 

would have minimal permanent and 

temporary impacts on benthic 

invertebrate species, a marine mammal 

prey source. In addition, it should be 

noted that the area in question is lowquality habitat since it is already highly 

developed and experiences a high level 

of anthropogenic noise from normal 

operations and other vessel traffic at the 

POA. In general, any negative impacts 

on marine mammal prey species are 

expected to be minor and temporary. 

In-Water Construction Effects on 

Potential Foraging Habitat 

The CTR project area is not 

considered to be high-quality habitat for 

marine mammals or marine mammal 

prey, such as fish, and it is anticipated 

that the long-term impact on marine 

mammals associated with CTR would be 

a small permanent decrease in lowquality potential habitat because of the 

expanded footprint of the new cargo 

terminals T1 and T2. The CTR project 

is not expected to result in any habitat 

related effects that could cause 

significant negative consequences for 

individual marine mammals or their 

populations since installation and 

removal of in-water piles would be 

temporary and intermittent and the 

increased footprint of the facilities 

would destroy only a small amount of 

low-quality habitat, which currently 

experiences high levels of 

anthropogenic activity. Therefore, 

impacts of the project are not likely to 

have adverse effects on marine mammal 

foraging habitat in the proposed project 

area. 

Estimated Take of Marine Mammals 

This section provides an estimate of 

the number of incidental takes proposed 

for authorization through promulgation 

of regulations and 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 (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 

(Level B harassment). 

Authorized takes would 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 (Level A harassment) 

to result, primarily for high frequency 

cetaceans and phocids because 

predicted auditory injury zones are 

larger than for mid-frequency cetaceans 

and otariids. Auditory injury is unlikely 

to occur for mysticetes, mid-frequency 

cetaceans, and otariids due to measures 

described in the Proposed Mitigation 

section. The proposed 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 proposed to 

be authorized for this activity. Below, 

we describe how the proposed take 

numbers are 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 


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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 proposed 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 PTS 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 (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-meansquared pressure received levels (RMS 

SPL) of 120 dB re 1 mPa for continuous 

(e.g., vibratory pile driving, drilling) and 

above RMS SPL 160 dB re 1 mPa for nonexplosive 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 (conspecific 

communication, predators, prey) may 

result in changes in behavior patterns 

that would not otherwise occur. 

The POA’s proposed 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 mPa are applicable. 

Level A harassment. NMFS’ Technical 

Guidance for Assessing the Effects of 

Anthropogenic Sound on Marine 

Mammal Hearing (Version 2.0; NMFS, 

2018) and the draft Updated Technical 

Guidance (NMFS, 2024) identify dual 

criteria to assess auditory injury (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 (impulsive or non-impulsive). 

This proposed rule estimates Level A 

harassment using the existing Technical 

Guidance (NMFS, 2018) as well as the 

draft Updated Technical Guidance 

(NMFS, 2024) because at the time of the 

final agency decision on this request for 

incidental take, it’s possible NMFS may 

have made a final agency decision on 

the draft Guidance. 

These thresholds are provided in the 

tables below. The references, analysis, 

and methodology used in the 

development of the thresholds are 

described in NMFS’ 2018 Technical 

Guidance and NMFS’ 2024 draft 

Updated Technical Guidance, both of 

which may be accessed at: https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/marinemammal-acoustic-technical-guidance. 

The POA’s proposed activity includes 

the use of impulsive (impact pile 

driving) and non-impulsive (vibratory 

driving) sources. 

TABLE 7—NMFS’ 2018 THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT (PTS) 

Hearing group 

PTS onset acoustic thresholds * 

(received level) 

Impulsive Non-impulsive 

Low-Frequency (LF) Cetaceans ...................................... Cell 1: Lpk,flat: 219 dB; LE,LF,24h: 183 dB ......................... Cell 2: LE,LF,24h: 199 dB. 

Mid-Frequency (MF) Cetaceans ...................................... Cell 3: Lpk,flat: 230 dB; LE,MF,24h: 185 dB ........................ Cell 4: LE,MF,24h: 198 dB. 

High-Frequency (HF) Cetaceans ..................................... Cell 5: Lpk,flat: 202 dB; LE,HF,24h: 155 dB ........................ Cell 6: LE,HF,24h: 173 dB. 

Phocid Pinnipeds (PW)(Underwater) ............................... Cell 7: Lpk,flat: 218 dB; LE,PW,24h: 185 dB ....................... Cell 8: LE,PW,24h: 201 dB. 

Otariid Pinnipeds (OW)(Underwater) ............................... Cell 9: Lpk,flat: 232 dB; LE,OW,24h: 203 dB ....................... Cell 10: LE,OW,24h: 219 dB. 

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS 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 (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s. 

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. 


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TABLE 8—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: Lp,0-pk,flat: 222 dB; LE,p,LF,24h: 183 dB .................. Cell 2: LE,p,LF,24h: 197 dB. 

High-Frequency (HF) Cetaceans ............................. Cell 3: Lp,0-pk,flat: 230 dB; LE,p,HF,24h: 193 dB ................. Cell 4: LE,p,HF,24h: 201 dB. 

Very High-Frequency (VHF) Cetaceans .................. Cell 5: Lp,0-pk,flat: 202 dB; LE,p,VHF,24h: 159 dB ............... Cell 6: LE,p,VHF,24h: 181 dB. 

Phocid Pinnipeds (PW) (Underwater) ...................... Cell 7: Lp,0-pk.flat: 223 dB; LE,p,PW,24h: 183 dB ................ Cell 8: LE,p,PW,24h: 195 dB. 

Otariid Pinnipeds (OW) (Underwater) ...................... Cell 9: Lp,0-pk,flat: 230 dB; LE,p,OW,24h: 185 dB ................ Cell 10: LE,p,OW,24h: 199 

dB. 

In-air: 

Phocid Pinnipeds (PA) (In-Air) ................................. Cell 11: Lp,0-pk.flat: 162 dB; LE,p,PA,24h: 140 dB ............... Cell 12: LE,p,PA,24h: 154 dB. 

Otariid Pinnipeds (OA) (In-Air) ................................. Cell 13: Lp,0-pk,flat: 177 dB; LE,p,OA,24h: 163 dB ............... Cell 14: LE,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 (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s. 

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 project area is 

the existing background noise plus 

additional construction noise from the 

proposed project. Marine mammals are 

expected to be affected via sound 

generated by the primary components of 

the project (i.e., impact pile removal and 

vibratory pile installation and removal). 

Calculation of the area ensonified by the 

proposed action is dependent on the 

background sound levels at the project 

site, the source levels of the proposed 

activities, and the estimated 

transmission loss coefficients for the 

proposed activities at the site. These 

factors are addressed in order, below. 

Background Sound Levels at the Port 

of Alaska—As noted in the Potential 

Effects of Specified Activities on Marine 

Mammals and Their Habitat section of 

this proposed rule, 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 proposed 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 Proposed 

Activities—The intensity of pile driving 

sounds is greatly influenced by factors 

such as the type of piles (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 proposed by the 

POA 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 9 and 10). The 

proposed 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 and 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 

and 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 meters. 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 meters, but no apparent 

broadband reduction was found in the 

far-field at about 2,800 meters (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 


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are most sensitive to frequencies over 

100 Hz, NMFS considers the use of 

bubble curtains during vibratory driving 

to be an effective and important 

mitigation measure for CIBW. 

Based on the aforementioned 

measurements conducted at POA, for 

vibratory driving during the CTR 

Project, it is assumed that a welldesigned and robust bubble curtain 

system will achieve a mean reduction of 

7 dB at the source and will also reduce 

sound levels at frequencies over 100 Hz 

at longer ranges. The POA proposes to 

use a bubble curtain when water depth 

is greater than 3 meters during vibratory 

installation of all permanent (72-in) 

piles and during vibratory driving of 

temporary (24-in or 36-in) piles during 

the months of August through October 

when CIBWs are most likely to be 

present. 

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 

proposed CTR activities (tables 9 and 

10). Impact driving of temporary piles 

(24-in and 36-in piles) is not currently 

proposed; 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 proposed. 

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 meters). 

It is currently unclear whether the 

POA’s proposed 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 proposes 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 meters. To 

account for piles driven in water less 

than 3m 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 

proposes to concurrently operate up to 

two hammers to install or extract piles 

at different parts of the project site, in 

order to reduce the need for pile driving 

during months of high beluga presence. 

When two noise sources have 

overlapping sound fields, the sources 

are considered additive and combined 

using the rules of dB addition. For 

addition of two simultaneous sources, 

the difference between the two 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 are 

shown in table 3; the predicted source 

values and transmission loss 

coefficients for these combinations are 

shown in table 11. 

Transmission Loss. For all piles 

driven with an active bubble curtain 

(‘‘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*Log10(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*Log10(range)). This value 

is an average of measurements obtained 

from two 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 proposed 

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, 2004), 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 proposes to 

use 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 proposed 

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 

two piles. The POA proposed, and 

NMFS concurs, that in the event that 

both piles are unattenuated, the TL 

coefficient would be 16.5; if both piles 

are attenuated, the TL coefficient would 

be 15. In the event that one pile is 

attenuated and one 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. 


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TABLE 9—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 inches in diameter. 

TABLE 10—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). 


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TABLE 11—SOURCE

VALUES FOR

POTENTIAL

CONCURRENT

DRIVING

SCENARIOS 1

Activity Method Pile type/size 2 Attenuated or unattenuated Proxy source value TL coefficient # Piles per day 3 dB RMS dB SEL dB peak 

Concurrent Driving (2 sources) ....................................... Vibratory/Vibratory ........ 36-in and 36-in ........... Attenuated/Attenuated ..............

Attenuated/Unattenuated ..........Unattenuated/Unattenuated ......

163.5 

169 

171 

............................................................

............................................................

15 

15.75 

16.5 

8 

8 

8 

36-in and 72-in ........... Attenuated/Attenuated ..............

Unattenuated/Attenuated ..........

166 

169 

........................................

........................................

15 

15.75 

7 7 

Vibratory/Impact 1 ......... 36-in and 72-in ........... Attenuated/Attenuated ..............

Unattenuated/Attenuated ..........

160.5/196 

166/196 

—/184 —/184 

—/210 —/210 

15/15 

16.5/15 

8 

7 

1 Concurrent vibratory and impact driving source values and TL coefficients are the same as for the piles driven individually (shown in tables 7 and 8), 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. 2POA 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. 3Piles 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). 


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85722 Federal Register / Vol. 89, No. 208 / Monday, October 28, 2024 / Proposed Rules 

Estimated Harassment Isopleths. All 

estimated Level B harassment isopleths 

are reported in tables 15 and 16. At 

POA, Level B harassment isopleths from 

the proposed project will be limited in 

some cases to less than the estimated 

value by the coastline along Knik Arm 

along and across from the 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 auditory injury. 

Inputs used in the optional User 

Spreadsheet tool and the resulting 

estimated isopleths are reported in 

tables 12 through 14, below. 

TABLE 12—NMFS USER SPREADSHEET INPUTS FOR 72-IN PERMANENT PILES

Impact pile driving Vibratory pile driving 

Attenuated Unattenuated 1 Attenuated Unattenuated 1

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 

1To account for piles driven in water less than 3m 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 13—NMFS USER SPREADSHEET INPUTS FOR TEMPORARY (24- OR 36-in) PILES

Vibratory pile driving 

24-in (61-cm) steel pipe 36-in (91-cm) steel pipe 

Installation Removal Installation Removal 

Atten. Unatten. Atten. Unatten. Atten. Unatten. 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 (dB RMS) .................................... 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) — 


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TABLE 13—NMFS USER SPREADSHEET INPUTS FOR TEMPORARY (24- OR 36-in) PILES—Continued 

Vibratory pile driving 

24-in (61-cm) steel pipe 36-in (91-cm) steel pipe 

Installation Removal Installation Removal 

Atten. Unatten. Atten. Unatten. Atten. Unatten. Atten. Unatten. 

Number of strikes per pile ................................. 1,000 

Piles per day ..................................................... 1 

Distance of sound pressure level measurement (m) ........................................................ 10 

TABLE 14—NMFS USER SPREADSHEET INPUTS FOR CONCURRENT VIBRATORY DRIVING

24- or 36-in AND 24-in or 36-in 24- or 36-in AND 72-in 

Attenuated/ 

attenuated 

Attenuated/ 

unattenuated 

Unattenuated/ 

unattenuated 

Attenuated/ 

attenuated 

Unattenuated/ 

attenuated 

Spreadsheet Tab Used .................................................... (A.1) 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 15—CALCULATED DISTANCE OF LEVEL A (BASED ON NMFS’ 2018 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) Level B 

harassment 

distance 

(m) all 

hearing 

groups 1

LF MF HF PW OW 

Impact ................................... 24-in (61-cm) .............. Unattenuated ........................ 735 27 876 394 29 1,585

Attenuated ............................ 251 9 299 135 10 541 

36-in (91-cm) .............. Unattenuated ........................ 1,165 42 1,387 624 46 1,585 

Attenuated ............................ 398 15 474 213 16 541 

72-in (182-cm) ............ Unattenuated ........................ 10,936 389 13,026 5,853 427 7,356 

Attenuated (1 pile per day) ... 3,734 133 4,448 1,999 146 2,512 

Attenuated (2 piles per day) 5,928 211 7,061 3,173 231 ........................

Attenuated (3 piles per day) 7,767 277 9,252 4,157 303 ........................

Vibratory Installation ............. 24-in (61-cm) .............. Unattenuated ........................ 11 2 16 7 1 2,247 

Attenuated ............................ 8 1 11 5 1 2,630 

36-in (91-cm) .............. Unattenuated ........................ 22 3 31 14 2 4,514 

Attenuated ............................ 11 1 15 7 1 3,575 

72-in (182-cm) ............ Unattenuated ........................ 19 3 27 12 2 9,069 

Attenuated ............................ 7 1 11 5 1 6,119 

Vibratory Removal ................ 24-in (61-cm) .............. Unattenuated ........................ 42 4.6 60 27 2.4 6,861 

Attenuated ............................ 16 1.7 23 11 1 2,583 

36-in (91-cm) .............. Unattenuated ........................ 11 2 15 7 1 1,699 

Attenuated ............................ 5 1 8 3 1 1,318 

Concurrent Vibratory ............. 36-in AND 36-in .......... Attenuated/Attenuated .......... 33 2.9 49 20 1.4 5,667 

Attenuated/Unattenuated ...... 81 8.0 118 51 4.0 9,363 

Unattenuated/Unattenuated .. 98 11 139 62 5.5 9,069 

36-in AND 72-in .......... Attenuated/Attenuated .......... 45 3.9 66 27 1.9 8,318 

Unattenuated/Attenuated ...... 75 7.4 108 47 3.7 9,363 

Concurrent Vibratory/Impact 36-in AND 72-in .......... Attenuated/Attenuated (1 pile 

per day).

3,734 133 4,448 1,999 146 3,575 

Attenuated/Attenuated (2 

piles per day).

5,928 211 7,061 3,173 231 ........................

Attenuated/Attenuated (3 

piles per day).

7,767 277 9,252 4,157 303 ........................

Unattenuated/Attenuated (1 

pile per day).

3,734 133 4,448 1,999 146 4,514 

Unattenuated/Unattenuated 

(2 piles per day).

5,928 211 7,061 3,173 231 ........................

Unattenuated/Attenuated (3 

piles per day).

7,767 277 9,252 4,157 303 ........................

1 Distances to thresholds are as modeled; however, interaction with shorelines would truncate zones. See figures 6–1 thorough 6–10 in the POA’s application for 

further details. 


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TABLE 16—CALCULATED DISTANCE AND AREAS OF LEVEL A (BASED ON NMFS’ PROPOSED 2024 UPDATE TO THE 2018 

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) Level B 

harassment 

distance (m) 

all hearing 

groups 1

LF HF VHF PW OW 

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 2,583 

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 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 

36-in AND 72-in .......... 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 thorough 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 will 

inform 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 table 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 NMFSfunded 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 NMFSfunded 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’ PSOs 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 17 shows the estimated 

occurrence rates for non-CIBW species 

at the POA; descriptions are provided in 

the text below. 


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TABLE 17—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 

proposed project area are rare. Few, if 

any, gray whales are expected to 

approach the proposed project area. 

However, based on three separate 

sightings of single gray whales near the 

POA in 2020 and 2021 (61N 

Environmental, 2021, 2022a; EasleyAppleyard and Leonard, 2022), the POA 

anticipates that up to six individuals 

could occur within estimated 

harassment zones each year during CTR 

project activities. 

Humpback Whale 

Sightings of humpback whales in the 

proposed project area are rare, and few, 

if any, humpback whales are expected 

to approach the proposed project area. 

However, there have been a few 

observations of humpback whales near 

the POA. Based on the two 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 Project area, the POA 

requested authorization of six takes of 

humpback whales per year 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 four 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 

two killer whales were sighted (61N 

Environmental, 2022a). Previous 

sightings of transient killer whales have 

documented pod sizes in upper Cook 

Inlet between one and six individuals 

(Shelden et al., 2003). While unlikely, it 

is possible that killer whales 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 one pod 

(assumed to be six individuals) could be 

taken by Level A harassment over the 5 

years of the CTR project. NMFS also 

concurs that no more than one pod 

(assumed to be six individuals) could 

occur within the Level B harassment 

zones during CTR project activities per 

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 proposed 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 proposed CTR area during the 5 

years covered under this proposed 

rulemaking. 

Steller Sea Lion 

Steller sea lions are anticipated to 

occur in low numbers within the 

proposed 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 nine individuals (eight during 

PCT Phase 1 monitoring and one 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, one individual was 

sighted, while on May 25, 2016, there 

were five 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 five 

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 


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levels at or above harassment thresholds 

over the course of the proposed 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 nine 

(eight during PCT Phase 1 monitoring 

and one 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 

proposes that nine Steller sea lions (the 

maximum number observed in a single 

year between 2020 and 2022 during 

projects with similar sized harassment 

isopleths) may be taken each year 

during the 5 years covered under this 

proposed rulemaking, up to a total of 45 

individuals over the course of the 

project. 

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 proposed 

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. 

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 two individual harbor 

seals, and only 0.6 percent of sightings 

reported three 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 a previous year was used 

to quantify take of harbor seals for inwater 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 

one 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 notice of 

proposed IHA 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 18), 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 18) 

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 (tables 15 

and 16). 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, we 

propose that CIBW observations should 

be 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 would help to ensure that 

the sighting rates used to estimate take 

are representative of CIBW presence in 

the proposed ensonified areas. 

TABLE 18—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 

1This 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. 


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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 proposed project 

site. The 2020–2022 marine mammal 

monitoring programs (table 18) 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 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; 

Easley-Appleyard and Leonard, 2022) 

and the CTR location midpoint, 

centered on the proposed 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 11,138 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 action site (figure 4). 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 4). 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 

195.7, 2,337.0, 3,154.7, and 6,973.9 m 

(figure 4). 

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., 195.7, 

2,337.0, 3,154.7, and 6,973.9 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 (xaxis) between the defining breakpoints, 

whereas a more level slope (i.e., closer 

to zero) indicates a lower accumulation 

of sightings over that linear distance (xaxis) between those defining 

breakpoints (figure 4; 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; 


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Figure 4 -- Percent of CIBW CPOA Observations in Relation to Distance from the CTR 

Project Site and Associated Breakpoints Determined by Piecewise Linear Regression 
85728 Federal Register / Vol. 89, No. 208 / Monday, October 28, 2024 / Proposed Rules 

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 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 195.7 m), 

with fewer CIBWs swimming in the 

center of Knik Arm (breakpoints 1 to 2, 

at 195.7 to 2,337 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 2,337 to 3,154.7 

m). Behaviors and locations beyond 

breakpoint 4 (6,973.9 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 6,973.9 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 five 

sighting rate distance bins for CIBWs in 

the NES1 project area. Each breakpoint 

(196, 2,337, 3,155, and 6,974 m, and the 

complete data set of observations 

[>6,974 m]) was rounded up to the 

nearest meter and considered the 

outermost limit of each sighting rate bin, 

resulting in five identified bins (table 

19). All CIBW observations less than 

each bin’s breakpoint distance were 

used to calculated that bin’s respective 

monthly sighting rates (e.g., all sightings 

from 0 to 196 m are included in the 

sighting rates calculated for bin number 

1, all sightings from 0 to 2,337 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 

the proposed rulemaking; therefore, 

monthly sighting rates were only 

derived for these months (table 19). 

TABLE 19—CIBW MONTHLY SIGHTING RATES FOR DIFFERENT SPATIALLY-BASED BIN SIZES

Bin number Distance 

(m) 

CIBW/Hour 1

April May June July August September October November 

1 ........................................................................ 196 0.05 0.06 0.10 0.04 0.82 0.59 0.51 0.10 

2 ........................................................................ 2,338 0.34 0.16 0.15 0.09 1.55 1.42 1.09 0.65 

3 ........................................................................ 3,155 0.36 0.22 0.21 0.09 2.02 1.89 1.98 0.72 

4 ........................................................................ 6,974 0.67 0.33 0.29 0.13 2.24 2.18 2.42 0.73 

5 ........................................................................ >6,974 0.71 0.39 0.30 0.13 2.29 2.23 2.56 0.73 

1Observation 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; Easley-Appleyard and Leonard, 2022). 

Take Estimation 

In this section, we describe how the 

information provided above is 

synthesized to produce a quantitative 

estimate of the take that is reasonably 

likely to occur and proposed for 

authorization. 

To quantitatively assess exposure of 

marine mammals to noise from pile 

driving activities, we used the 

occurrence estimate (number/unit of 

time; tables 17 and 19) and the 

estimated work hours per year (table 20) 

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 Proposed 

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 20) for all 

species except killer whales, which 

have smaller predicted Level A 

harassment zones, and CIBWs, which 

have larger proposed shutdown zones, 

described in further detail below. 

TABLE 20—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 ....................................................................................................................... 98.90 55.00 153.90 0.64 

2 ....................................................................................................................... 87.43 47.92 135.35 0.65 

3 ....................................................................................................................... 38.70 96.50 135.20 0.29 

4 ....................................................................................................................... 87.43 50.42 137.85 0.63 

5 ....................................................................................................................... 81.70 55.50 137.20 0.60 

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 17, and proportion of impact 

hammer use per year from table 20. 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 

proposes to 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 


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each species not to exceed the maximum annual values shown in 

tables 21, 22, and 24. 

TABLE 21—ESTIMATED TAKE BY LEVEL A HARASSMENT IN EACH OF THE 5 YEARS AND IN TOTAL FOR NON-CIBW MARINE

MAMMAL SPECIES IN THE PROPOSED CTR PROJECT AREA 1

Species 

Potential 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 

1Annual take may not be distributed exactly as shown; NMFS proposes to authorize 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. 

Proposed 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 17 or calculated as the hourly 

occurrence from table 17 multiplied by 

the total yearly duration in table 20) for 

each stock. 

TABLE 22—ESTIMATED TAKE BY LEVEL B HARASSMENT IN EACH OF THE 5 YEARS AND IN TOTAL FOR NON-CIBW MARINE

MAMMAL SPECIES IN THE PROPOSED CTR PROJECT AREA 1

Stock 

Potential 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 

1Annual take may not be distributed exactly as shown; NMFS proposes to authorize total take over the 5 year construction period, not to exceed the sum of the maximum annual values shown in years 1–5 in Tables 21 and 22. 

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 (table 2) with the 

corresponding sighting rate month and 

sighting rate distance bin (table 19). 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 19). Therefore, take for this 

activity is 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 19). The resulting estimated 

CIBW exposures were totaled for all 

activities in each month (table 23). 

In their calculation of CIBW take, the 

POA assumed that only 36-in template 

piles would be installed (rather than 24- 

in) and removed during the 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. Using the 

monthly activity estimates in hours 

(table 2) and monthly calculated 

sighting rates (CIBWs/hour) for the 

spatially derived distance bins (table 

23), we estimated take by Level B 

harassment for each of the 5 years of the 

CTR project (table 24). 


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TABLE 23—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 number 

and distance 

Belugas/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 (2,338 m) .... 0.34 0.16 0.15 0.09 1.55 1.42 1.09 0.65 

36-in Vibratory Installation 1 2 ....................................... 4,514 4 (6,974 m) .... 0.67 0.33 0.29 0.13 2.24 2.18 2.42 0.73 

72-in Vibratory Installation 3 .......................................... 9,069 5 (>6,974) ....... 0.71 0.39 0.30 0.13 2.29 2.23 2.56 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 (2,338 m) .... 0.34 0.16 0.15 0.09 1.55 1.42 1.09 0.65 

72-in Impact Installation 3 ............................................. 7,356 5 (>6,974) ....... 0.71 0.39 0.30 0.13 2.29 2.23 2.56 0.73 

Attenuated Values (with the use of a bubble curtain) 

36-in Vibratory Removal 2 ............................................. 1,318 2 (2,338) ......... 0.34 0.16 0.15 0.09 1.55 1.42 1.09 0.65 

36-in Vibratory Installation 2 .......................................... 3,575 4 (6,974 m) .... 0.67 0.33 0.29 0.13 2.24 2.18 2.42 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 (>6,974) ....... 0.71 0.39 0.30 0.13 2.29 2.23 2.56 0.73 

36-in Impact Installation 1 2 ........................................... 541 2 (2,338) ......... 0.34 0.16 0.15 0.09 1.55 1.42 1.09 0.65 

72-in Impact Installation ............................................... 2,512 3 (3,155 m) .... 0.36 0.22 0.21 0.09 2.02 1.89 1.98 0.72 

1 Unattenuated vibratory and impact driving of temporary and 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. 4Both 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 Proposed 

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 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 proposed project area. 

Between the two 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 CTR. 

NMFS proposes that the 59-percent 

adjustment accurately accounts for the 

efficacy of the POA’s marine mammal 

monitoring program and required 

shutdown protocols, based on past 

performance. NMFS, therefore, assumes 

that approximately 59 percent of the 

takes calculated for CTR may actually be 

realized (table 24). Take by Level A 

harassment is not anticipated or 

proposed to be 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 Proposed 

Mitigation section for more 

information). 

TABLE 24—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′′ vibratory installation 3 .................................................................. 1.68 2.01 1.76 0.78 13.44 13.10 7.26 1.47 

36′′ vibratory removal 3 ...................................................................... 0.26 0.12 0.11 0.07 1.16 1.06 0.82 0.49 


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TABLE 24—CALCULATED LEVEL B HARASSMENT TAKES OF CIBWS BY MONTH, YEAR, AND ACTIVITY 1—Continued 

Apr May Jun Jul Aug 2 Sep 2 Oct 2 Nov 

72′′ vibratory installation (attenuated) ............................................... 0.50 0.59 0.51 0.23 3.17 3.09 3.43 0.06 

72′′ vibratory installation (unattenuated) 4 ......................................... 0.06 0.03 0.03 0.01 0.19 0.19 0.21 0.06 

72′′ impact installation (attenuated) .................................................. 2.35 3.36 3.19 1.40 24.67 23.08 24.18 3.62 

72′′ impact installation (unattenuated) 4 ............................................ 0.49 0.27 0.21 0.09 1.60 1.56 1.79 0.51 

Year 1 total ................................................................................ ................ ................ ................ ................ ................ ................ ................ 151 

With 59% Correction Factor 5 .................................................... ................ ................ ................ ................ ................ ................ ................ 90 

Year 2 1

36′′ vibratory installation 3 .................................................................. 2.01 1.67 1.47 0.65 11.20 10.91 6.05 1.47 

36′′ vibratory removal 3 ...................................................................... 0.26 0.12 0.11 0.07 1.16 1.06 0.82 0.00 

72′′ vibratory installation (attenuated) ............................................... 0.50 0.47 0.42 0.18 3.17 2.73 3.03 0.43 

72′′ vibratory installation (unattenuated) 4 ......................................... 0.06 0.03 0.03 0.01 0.19 0.19 0.21 0.06 

72′′ impact installation (attenuated) .................................................. 2.35 2.72 2.58 1.14 24.67 20.36 21.34 3.62 

72′′ impact installation (unattenuated) 4 ............................................ 0.49 0.27 0.21 0.09 1.60 1.56 1.79 0.51 

Year 2 total ................................................................................ ................ ................ ................ ................ ................ ................ ................ 137 

With 59% Correction Factor 5 .................................................... ................ ................ ................ ................ ................ ................ ................ 81 

Year 3 1

36′′ vibratory installation 3 .................................................................. 4.36 4.35 3.82 1.68 29.13 28.38 15.73 1.47 

36′′ vibratory removal 3 ...................................................................... 0.26 0.37 0.34 0.21 2.33 2.12 0.82 0.49 

72′′ vibratory installation (attenuated) ............................................... 0.39 0.20 0.17 0.05 0.93 0.91 1.01 0.31 

72′′ vibratory installation (unattenuated) 4 ......................................... 0.06 0.03 0.03 0.01 0.19 0.19 0.21 0.06 

72′′ impact installation (attenuated) .................................................. 1.83 1.12 1.07 0.34 7.28 6.81 7.13 2.59 

72′′ impact installation (unattenuated) 4 ............................................ 0.49 0.27 0.21 0.09 1.60 1.56 1.79 0.51 

Year 3 total ................................................................................ ................ ................ ................ ................ ................ ................ ................ 136 

With 59% Correction Factor 5 .................................................... ................ ................ ................ ................ ................ ................ ................ 81 

Year 4 1

36′′ vibratory installation 3 .................................................................. 4.36 4.35 3.82 1.68 29.13 28.38 15.73 1.47 

36′′ vibratory removal 3 ...................................................................... 0.26 0.37 0.34 0.21 2.33 2.12 0.82 0.49 

72′′ vibratory installation (attenuated) ............................................... 0.39 0.20 0.17 0.05 0.93 0.91 1.01 0.31 

72′′ vibratory installation (unattenuated) 4 ......................................... 0.06 0.03 0.03 0.01 0.19 0.19 0.21 0.06 

72′′ impact installation (attenuated) .................................................. 1.83 1.12 1.07 0.34 7.28 6.81 7.13 2.59 

72′′ impact installation (unattenuated) 4 ............................................ 0.49 0.27 0.21 0.09 1.60 1.56 1.79 0.51 

Year 4 total ................................................................................ ................ ................ ................ ................ ................ ................ ................ 138 

With 59% Correction Factor 5 .................................................... ................ ................ ................ ................ ................ ................ ................ 82 

Year 5 1

36′′ vibratory installation 3 .................................................................. 1.68 2.01 1.76 0.78 13.44 12.00 13.31 1.84 

36′′ vibratory removal 3 ...................................................................... 0.26 0.12 0.11 0.07 1.16 1.06 0.82 0.49 

72′′ vibratory installation (attenuated) ............................................... 0.28 0.47 0.42 0.18 2.80 2.73 3.03 0.31 

72′′ vibratory installation (unattenuated) 4 ......................................... 0.06 0.03 0.03 0.01 0.19 0.19 0.21 0.06 

72′′ impact installation (attenuated) .................................................. 1.31 2.72 2.58 1.14 21.77 20.36 21.34 2.59 

72′′ impact installation (unattenuated) 4 ............................................ 0.49 0.27 0.21 0.09 1.60 1.56 1.79 0.51 

Year 5 total ................................................................................ ................ ................ ................ ................ ................ ................ ................ 143 

With 59% Correction Factor 5 .................................................... ................ ................ ................ ................ ................ ................ ................ 85 

Years 1–5 Total 

Project Total Estimated Exposures ........................................... ................ ................ ................ ................ ................ ................ ................ 705 

With 59% Correction Factor 5 .................................................... ................ ................ ................ ................ ................ ................ ................ 419 

1 Concurrent driving scenarios that would improve the production efficiency in the months of April through July have been conservatively excluded from this analysis. 2 Unattenuated vibratory driving of temporary and 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 <3m. 3Attenuated and unattenuated bins for this activity are the same. 

4 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. This calculation assumes 0.5 72-in piles per month may be driven in water depths <3m and thus be unattenuated. 5 Corrected exposure estimates have been rounded up for each year (e.g., Year 1 = 0.59 * 151 = 89.1, which has been rounded up to 90). 

In summary, the maximum annual 

amount of Level A harassment and 

Level B harassment proposed to be 

authorized for each marine mammal 

stock is presented in table 25. 


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TABLE 25—NUMBER OF PROPOSED TAKES AS A PERCENTAGE OF STOCK ABUNDANCE, BY STOCK AND HARASSMENT TYPE

FOR THE MAXIMUM ANNUAL ESTIMATED TAKES OF THE PROJECT

Species 

Proposed take 

Stock Percent of 

stock Level A Level B Total 

Gray whale .............................................. 4 2 6 Eastern North Pacific .............................. 0.02 

Humpback whale 1 .................................. 3 1 4 Hawai1i .................................................... 0.04 

Mexico-North Pacific ............................... 2 UNK 

Beluga whale .......................................... 0 90 90 Cook Inlet 3 ............................................. 27.2 

Killer whale 1 ........................................... 6 6 12 Eastern North Pacific Alaska Resident .. 0.6 

Eastern North Pacific Gulf of Alaska, 

Aleutian Islands and Bering Sea Transient.

2.04 

Harbor porpoise ...................................... 16 8 24 Gulf of Alaska ......................................... 0.08 

Steller sea lion ........................................ 6 3 9 Western .................................................. 0.015 

Harbor seal ............................................. 99 55 154 Cook Inlet/Shelikof Strait ........................ 0.54 

1 NMFS conservatively assumes that all takes occur to each stock 

2 NMFS does not have an official abundance estimate for this stock and the minimum population estimate is considered to be unknown (Young 

et al., 2023). See Small Numbers for additional discussion. 3This abundance estimate is from Goetz et al. (2023); which was published after the most recent CIBW SAR (Young et al., 2023). 

Proposed Mitigation 

In order to promulgate a rulemaking 

under section 101(a)(5)(A) of the 

MMPA, NMFS must set forth the 

permissible methods of taking pursuant 

to the activity and other means of 

effecting the least practicable adverse 

impact on the species or stock and its 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance and on the 

availability of the species or stock for 

taking for certain subsistence uses (latter 

not applicable for this action). NMFS 

regulations require applicants for 

incidental take authorizations to include 

information about the availability and 

feasibility (economic and technological) 

of equipment, methods, and manner of 

conducting the activity or other means 

of effecting the least practicable adverse 

impact upon the affected species or 

stocks, and their habitat (50 CFR 

216.104(a)(11)). 

In evaluating how mitigation may or 

may not be appropriate to ensure the 

least practicable adverse impact on 

species or stocks and their habitat, as 

well as subsistence uses where 

applicable, NMFS considers two 

primary factors: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure(s) is 

expected to reduce impacts to marine 

mammals, marine mammal species or 

stocks, and their habitat. This considers 

the nature of the potential adverse 

impact being mitigated (likelihood, 

scope, range). It further considers the 

likelihood that the measure will be 

effective if implemented (probability of 

accomplishing the mitigating result if 

implemented as planned), the 

likelihood of effective implementation 

(probability implemented as planned), 

and; 

(2) The practicability of the measures 

for applicant implementation, which 

may consider factors such as cost and 

impact on operations. 

The POA presented mitigation 

measures in section 11 of their 

application that were modeled after the 

requirements included in the IHAs 

issued for Phase 1 and Phase 2 PCT 

construction (85 FR 19294, April 6, 

2020) and for SFD construction (86 FR 

50057, September 7, 2021), which were 

designed to minimize the total number, 

intensity, and duration of harassment 

events for CIBWs and other marine 

mammal species during those projects 

(61N Environmental, 2021, 2022a, 

2022b). NMFS concurs that these 

proposed measures reduce the potential 

for CIBWs and other marine mammals 

to be adversely impacted by the 

proposed activity. 

Noise Mitigation for Pile Installation 

and Removal—The POA has previously 

utilized and assessed the effectiveness 

of bubble curtains for noise mitigation at 

the project site (Austin et al. 2016; 

Illingworth and Rodkin, LLC (I&R) 

2021a, 2021b, 2023). In all previous 

years of the PAMP, bubble curtains were 

not used on piles installed or removed 

in shallow water less than 3 meters deep 

or piles installed or removed ‘‘in the 

dry’’ (e.g., at times when the tide is low 

and the pile’s location is dewatered) 

because low water levels prevent proper 

deployment and function of a bubble 

curtain system. When a pile was 

installed or removed in the dry, it was 

assumed that no exposure to received 

sound levels equated with potential 

incidental harassment occurred and, 

therefore, that no take of marine 

mammals occurred. The same 

assumptions and approach to mitigation 

associated with use of a bubble curtain 

have been used in the analyses for this 

project. 

NMFS is proposing that the POA must 

employ the following mitigation 

measures: 

• Ensure that construction 

supervisors and crews, the monitoring 

team and relevant POA staff are trained 

prior to the start of all pile driving, so 

that responsibilities, communication 

procedures, monitoring protocols, and 

operational procedures are clearly 

understood. New personnel joining 

during the project must be trained prior 

to commencing work; 

• Employ PSOs and establish 

monitoring locations as described in the 

POA’s Marine Mammal Monitoring and 

Mitigation Plan (see appendix B of the 

POA’s application). The POA must 

monitor the project area to the 

maximum extent possible based on the 

required number of PSOs, required 

monitoring locations, and 

environmental conditions; 

• Monitoring must take place from 30 

minutes prior to initiation of pile 

driving (i.e., pre-clearance monitoring) 

through 30 minutes post-completion of 

pile driving; 

• Pre-start clearance monitoring must 

be conducted during periods of 

visibility sufficient for the lead PSO to 

determine that the shutdown zones 

indicated in table 26 are clear of marine 

mammals. Pile driving may commence 

following 30 minutes of observation 

when the determination is made that the 

shutdown zones are clear of marine 

mammals or when the mitigation 

measures proposed specifically for 

CIBWs (below) are satisfied; 

• If work ceases for more than 30 

minutes, PSOs must observe a 30- 

minute pre-start clearance period (i.e., 


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the shutdown zones must be observed 

for 30 minutes and confirmed clear of 

marine mammals) prior to reinitiating 

pile driving. A determination that the 

shutdown zone is clear must be made 

during a period of good visibility. 

• For all construction activities, 

shutdown zones must be established 

following table 26. The purpose of a 

shutdown zone is generally to define an 

area within which shutdown of activity 

would occur upon sighting of a marine 

mammal entering or within the defined 

area. The shutdown zones (table 26) 

were calculated based on the minimum 

100-m shutdown zone proposed by the 

POA for all pile installation and 

vibratory extraction activities, as well as 

the calculated Level A (non-CIBW 

species) and Level B (CIBWs) 

harassment isopleths shown in table 16. 

In most cases, the shutdown zones 

exceed the calculated Level A isopleths; 

exceptions occur during impact pile 

driving, when the calculated Level A 

harassment isopleths exceed practicable 

shutdown zones for non-CIBW species, 

and during concurrent vibratory driving 

(the largest Level A isopleth is 161 m 

during this activity). For CIBWs, the 

shutdown zones exceed the calculated 

Level B harassment isopleths in all 

scenarios. 

TABLE 26—PROPOSED SHUTDOWN ZONES DURING SPECIFIED ACTIVITIES

Activity Pile type/size Attenuated or 

unattenuated 

Shutdown zone (m) 

LF 

cetaceans 

Non-CIBW 

MF 1

cetaceans 

CIBWs HF 1

cetaceans PW OW 

Vibratory Installation ......... 24-in ............................ Unattenuated .................... 100 100 2,250 100 100 100 

36-in ............................ 4,520 

72-in ............................ .

72-in ............................ 9,100 

24-in ............................ Attenuated ........................ 2,630 

36-in ............................ 3,580 

72-in ............................ 6,120 

Vibratory Removal ............ 24-in ............................ Unattenuated .................... 5,970 

36-in ............................ 1,700 

24-in ............................ Attenuated ........................ 2,100 

36-in ............................ 1,320 

Impact Installation—1 pile 

per day.

24-in ............................

36-in ............................

Unattenuated .................... 500 500 1,600 500 100 100 

24-in ............................

36-in ............................

Attenuated ........................ 100 100 550 100 100 100 

Impact Installation—1 pile 

per day.

72-in ............................ Unattenuated .................... 500 500 7,360 500 100 100 

Attenuated ........................ 2,520 

Impact Installation—2 piles 

per day.

Impact Installation—3 piles 

per day.

Concurrent—2 Vibratory 

sources.

36-in ............................

AND ............................

36-in ............................

Attenuated/Attenuated ......

Attenuated/Unattenuated ..

Unattenuated/ 

Unattenuated.

100 100 5,670 

9,370 

9,070 

100 100 100 

36-in ............................

AND ............................

72-in ............................

Attenuated/Attenuated ......

Unattenuated/Attenuated ..

8,320 

9,370 

Concurrent Vibratory/Impact.36-in ............................

AND ............................

72-in ............................

Attenuated/Attenuated (1 

pile per day).

Attenuated/Attenuated (2 

piles per day).

Attenuated/Attenuated (3 

piles per day).

500 500 3,580 500 100 100 

Unattenuated/Attenuated 

(1 pile per day).

Unattenuated/Attenuated 

(2 piles per day).

Unattenuated/Attenuated 

(3 piles per day).

4,520 

Notes: cm = centimeter(s), m = meter(s); 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. 1 In the Updated Technical Guidance (NMFS, 2024), the MF Cetacean hearing group has been re-named the HF Cetacean group; HF Cetaceans from the 2018 

Technical Guidance have been re-named VHF Cetaceans. 

• Marine mammals observed 

anywhere within visual range of the 

PSO must be tracked relative to 

construction activities. If a marine 

mammal is observed entering or within 

the shutdown zones indicated in table 

26, pile driving must be delayed or 

halted. If pile driving is delayed or 

halted due to the presence of a marine 

mammal, the activity may not 

commence or resume until either the 

animal has voluntarily exited and been 

visually confirmed beyond the 

shutdown zone (table 26), or 15 minutes 

(non-CIBWs) or 30 minutes (CIBWs) 

have passed without re-detection of the 

animal; 

• The POA must use bubble curtains 

for all piles during both vibratory and 

impact pile driving in water depths 

greater than 3 m during the months of 

August through October. No bubble 

curtain is required for vibratory pile 

driving of temporary (24-in or 36-in) 

piles in the months of April–July (see 

discussion below). Bubble curtains must 


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be used for all permanent (72-in) piles 

during both vibratory and impact pile 

driving in waters deeper than 3 m in the 

months of April–November. The bubble 

curtain must be operated as necessary to 

achieve optimal performance. At a 

minimum, the bubble curtain must 

distribute air bubbles around 100 

percent of the piling circumference for 

the full depth of the water column; the 

lowest bubble ring must be in contact 

with the substrate for the full 

circumference of the ring; and air flow 

to the bubblers must be balanced around 

the circumference of the pile. 

• The POA must use soft start 

techniques when impact pile driving. 

Soft start requires contractors to provide 

an initial set of three strikes at reduced 

energy, followed by a 30-second waiting 

period, then two subsequent reduced 

energy strike sets. A soft start must be 

implemented at the start of each day’s 

impact pile driving and at any time 

following cessation of impact pile 

driving for a period of 30 minutes or 

longer. PSOs shall begin observing for 

marine mammals 30 minutes before 

‘‘soft start’’ or in-water pile installation 

or removal begins; 

• Pile driving activity must be halted 

upon observation of either a species for 

which incidental take is not authorized 

or a species for which incidental take 

has been authorized but the authorized 

number of takes has been met, entering 

or within the harassment zone; and 

• The POA must avoid direct 

physical interaction with marine 

mammals during non-pile-driving 

construction activities, including barge 

positioning and pile cutting. If a marine 

mammal comes within 10 m of such 

activity, operations shall cease. Should 

a marine mammal come within 10 m of 

a vessel in transit, the boat operator will 

reduce vessel speed to the minimum 

level required to maintain steerage and 

safe working conditions. If human safety 

is at risk, based on the best judgment of 

the vessel captain or project engineer, 

the in-water activity is allowed to 

continue until it is safe to stop. 

The following additional mitigation 

measures are proposed by NMFS for 

CIBWs: 

• Prior to the onset of pile driving, 

should a CIBW be observed approaching 

the estimated shutdown zone (table 26) 

(i.e. the CIBWs Level B harassment zone 

column in tables 15 and 16), pile 

driving must not commence until the 

whale(s) moves at least 100 m past the 

estimated shutdown zone and on a path 

away from the zone, or the whale has 

not been re-sighted within 30 minutes; 

• If pile installation or removal has 

commenced and a CIBW(s) is observed 

within or likely to enter the shutdown 

zone, pile installation or removal must 

shut down and not re-commence until 

the whale has traveled at least 100 m 

beyond the shutdown zone and is on a 

path away from such zone or until no 

CIBW has been observed in the 

shutdown zone for 30 minutes; and 

• If during installation and removal of 

piles, PSOs can no longer effectively 

monitor the entirety of the CIBW 

shutdown zone due to environmental 

conditions (e.g., fog, rain, wind), pile 

driving may continue only until the 

current segment of the pile is driven; no 

additional sections of pile or additional 

piles may be driven until conditions 

improve such that the shutdown zone 

can be effectively monitored. If the 

shutdown zone cannot be monitored for 

more than 15 minutes, the entire 

shutdown zone will be cleared again for 

30 minutes prior to pile driving. 

In addition to these mitigation 

measures being proposed by NMFS, 

NMFS requested that the POA restrict 

all pile driving and removal work to 

April to July, when CIBWs are typically 

found in lower numbers. However, the 

POA stated that given the scale of the 

project, construction sequencing 

requirements, critical nature of the CTR 

infrastructure and overall PAMP, and 

vulnerability of the existing cargo 

terminals to seismic events, it cannot 

commit to restricting pile driving and 

removal to April to July. Instead, the 

POA would complete as much work as 

is practicable in April to July to reduce 

the amount of pile driving and removal 

activities in August through November. 

The POA is aware that August through 

October are months with high CIBW 

abundance and plans to complete inwater work as early in the construction 

season as possible. The POA also 

recognizes that more work shutdowns 

for CIBW are likely to take place in high 

abundance months, which provides 

incentive to complete work earlier in 

the season. 

Due to the deterioration of the current 

facilities and complexity of the PAMP, 

it is important that the POA attempt to 

complete the CTR project as currently 

proposed (6 years in total), which 

requires the POA to make full use of the 

available annual construction window 

(August through October/November). 

Potential consequences of pausing the 

construction season (e.g., stopping work 

from August through October) include 

de-rating of the structural capacity of 

the existing cargo terminals, 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 

before T1 and T2 replacement. 

For previous IHAs issued to the POA 

(PCT: 85 FR 19294, April 6, 2020; SFD: 

86 FR 50057, September 7, 2021), the 

use of a bubble curtain to reduce noise 

has been required as a mitigation 

measure for certain pile driving 

scenarios. The POA has concerns about 

effectiveness of bubble curtains in the 

far-field during vibratory pile driving 

(see Appendix A of the POA’s 

application for further details). NMFS 

disagrees with the POA’s assertion of 

effectiveness but acknowledges 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 

project area, thus lengthening the 

duration of potential interactions 

between CIBW and in-water work. 

Therefore, NMFS is concerned that use 

of a bubble curtain for all piles in all 

months may ultimately result in 

increased impacts to CIBW. Given the 

extensive proposed visual monitoring 

and mitigation measures in place, and 

in order to facilitate increased 

production when CIBW abundance at 

POA is expected to be lowest, NMFS 

concurs that the POA’s proposal to use 

vibratory hammers to install and extract 

temporary piles with no bubble curtain 

during the months of April through July 

affects the least practicable adverse 

impact on marine mammals. A bubble 

curtain would be required during all 

installation of permanent piles in all 

months, and for vibratory driving of 

temporary piles in August through 

October. 

NMFS considered additional 

mitigation and monitoring requirements 

for the CTR project, including soundsource verification measurements and 

passive acoustic monitoring of marine 

mammals near the POA. Sound source 

verification is time-intensive and 

expensive, and the POA has previously 

collected data on most of the pile types 

proposed for the CTR project 

(Illingworth and Rodkin, 2021a, b). 

Following discussion with the POA, 

NMFS determined that conducting 

additional sound source verification 

measurements would not be practicable 

or provide support for additional 

mitigation value due to schedule 

concerns and the volume of data already 

collected and, therefore, this measure 

was eliminated from the suite of 

proposed mitigation requirements. 

However, depending on future project 

conditions, the POA may choose to 

conduct sound source verification 

measurements and work with NMFS to 


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revise the estimated harassment zones 

as indicated by the data collected. 

With respect to passive acoustic 

monitoring, available technologies to 

detect marine mammals in near realtime require a surface buoy for the 

device, and mooring locations would be 

limited by ongoing port operations, 

construction activities, and dredging. 

The high noise environment at the POA 

(from both anthropogenic and natural 

sources) would add additional 

limitations to the detection range of 

such devices. Therefore, NMFS believes 

that the POA’s extensive and successful 

visual monitoring program represents 

the best possible method of minimizing 

effects to marine mammals, including 

CIBWs to pile driving noise, and that 

passive acoustic monitoring would not 

provide additional benefits to marine 

mammals in this case. 

Based on our evaluation of the 

applicant’s proposed measures, as well 

as other measures considered by NMFS, 

NMFS has preliminarily determined 

that the proposed mitigation measures 

provide the means of affecting the least 

practicable impact on the affected 

species or stocks and their habitat, 

paying particular attention to rookeries, 

mating grounds, and areas of similar 

significance. 

Proposed Monitoring and Reporting 

In order to promulgate a rulemaking 

for an activity, section 101(a)(5)(A) of 

the MMPA states that NMFS must set 

forth requirements pertaining to the 

monitoring and reporting of such taking. 

The MMPA implementing regulations at 

50 CFR 216.104(a)(13) indicate that 

requests for authorizations must include 

the suggested means of accomplishing 

the necessary monitoring and reporting 

that will result in increased knowledge 

of the species and of the level of taking 

or impacts on populations of marine 

mammals that are expected to be 

present in the specified geographical 

region. Effective reporting is critical 

both to compliance as well as ensuring 

that the most value is obtained from the 

required monitoring. 

Monitoring and reporting 

requirements prescribed by NMFS 

should contribute to improved 

understanding of one or more of the 

following: 

• Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density); 

• Nature, scope, or context of likely 

marine mammal exposure to potential 

stressors/impacts (individual or 

cumulative, acute or chronic), through 

better understanding of: (1) action or 

environment (e.g., source 

characterization, propagation, ambient 

noise); (2) affected species (e.g., life 

history, dive patterns); (3) co-occurrence 

of marine mammal species with the 

activity; or (4) biological or behavioral 

context of exposure (e.g., age, calving or 

feeding areas); 

• Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors; 

• How anticipated responses to 

stressors impact either: (1) long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks; 

• Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat); and, 

• Mitigation and monitoring 

effectiveness. 

The POA’s draft Marine Mammal 

Monitoring and Mitigation Plan is 

Appendix B of the LOA application, and 

is available on regulations.gov and at 

https://www.fisheries.noaa.gov/action/ 

incidental-take-authorization-portalaskas-construction-activities-portalaska-modernization. The POA 

proposes to implement a marine 

mammal monitoring and mitigation 

strategy intended to avoid and minimize 

impacts to marine mammals. Marine 

mammal monitoring would be 

conducted at all times when in-water 

pile installation and removal is taking 

place. Prior to the beginning of 

construction, POA would submit a 

revised Marine Mammal Mitigation and 

Monitoring Plan containing additional 

details of monitoring locations and 

methodology for NMFS concurrence. 

The marine mammal monitoring and 

mitigation program that is planned for 

CTR construction would be modeled 

after the successful monitoring and 

mitigation programs outlined in the 

IHAs for Phase 1 and Phase 2 PCT 

construction (85 FR 19294, April 6, 

2020) and the IHAs for SFD (86 FR 

50057, September 7, 2021) and NES1 

(89 FR 2832, January 14, 2024) 

construction. These monitoring 

programs have provided the best 

available data on CIBW and other 

marine mammal presence at the POA 

and continue to be used successfully as 

of July 2024 at the NES1 project. 

Visual Monitoring 

Monitoring must be conducted by 

qualified, NMFS-approved PSOs, in 

accordance with the following: 

• PSOs must be independent of the 

activity contractor (e.g., employed by a 

subcontractor) and have no other 

assigned tasks during monitoring 

periods. At least one PSO at each 

monitoring station must have prior 

experience performing the duties of a 

PSO during construction activity 

pursuant to a NMFS-issued ITA or 

Letter of Concurrence. Other PSOs may 

substitute other relevant experience 

(including relevant Alaska Native 

traditional knowledge), education 

(degree in biological science or related 

field), or training for prior experience 

performing the duties of a PSO. PSOs 

must be approved by NMFS prior to 

beginning any activity subject to this 

ITA; 

• The POA must employ PSO stations 

at a minimum of four locations from 

which PSOs can effectively monitor the 

shutdown zones (table 24). PSO stations 

must be positioned at the best practical 

vantage points that are determined to be 

safe. Likely locations include the 

Anchorage Downtown Viewpoint near 

Point Woronzof, the Anchorage Public 

Boat Dock at Ship Creek, the CTR 

Project site, and the North End of POA 

property (see figure 13–1 in the POA’s 

application for potential locations of 

PSO stations). Areas near Cairn Point or 

Port MacKenzie have safety, security, 

and logistical issues, which would need 

to be considered. Cairn Point proper is 

located on military land and has bear 

presence, and restricted access does not 

allow for the location of an observation 

station at this site. Tidelands along 

Cairn Point are accessible only during 

low tide conditions and have inherent 

safety concerns of being trapped by 

rising tides. Port MacKenzie is a secure 

port that is relatively remote, creating 

safety, logistical, and physical staffing 

limitations due to lack of nearby lodging 

and other facilities. The roadway travel 

time between port sites is approximately 

2–3 hours. An additional possible 

monitoring location is proposed north of 

the proposed project site, pending 

selection of the Construction Contractor 

and more detailed discussions before 

the start of construction. Temporary 

staffing of a northerly monitoring station 

during peak marine mammal presence 

time periods and/or when shutdown 

zones are large would be considered by 

the POA, NMFS, and the construction 

contractor based on evaluation of CIBW 

occurrence reported in the required 

weekly monitoring reports. At least one 

PSO station must be able to fully 

observe the non-CIBW shutdown zones; 

multiple PSO stations will be necessary 

to fully observe the CIBW shutdown 

zones (table 24); 

• PSO stations must be elevated 

platforms constructed on top of 

shipping containers or a similar base 


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that is at least 8′6′′ high (i.e., the 

standard height of a shipping container) 

that can support at least three PSOs and 

their equipment. The platforms must be 

stable enough to support use of a 

theodolite and must be located to 

optimize the PSO’s ability to observe 

marine mammals and the harassment 

zones; 

• Each PSO station must have at least 

two PSOs on watch at any given time; 

one PSO must be observing and one 

PSO would be recording data (and 

observing when there are no data to 

record). Teams of three PSOs would 

include one PSO who would be 

observing, and one PSO who would be 

recording data (and observing when 

there are no data to record). The third 

PSO may help to observe, record data, 

or rest. In addition, if POA is 

conducting in-water work on other 

projects that includes PSOs, the CTR 

PSOs must be in real-time contact with 

those PSOs, and both sets of PSOs must 

share all information regarding marine 

mammal sightings with each other; 

• A designated lead PSO must always 

be on site. The lead observer must have 

prior experience performing the duties 

of a PSO during in-water construction 

activities pursuant to a NMFS-issued 

ITA or Letter of Concurrence. Each PSO 

station must also have a designated 

Station Lead PSO specific to that station 

and shift. These Station Lead PSOs must 

have prior experience working as a PSO 

during in-water construction activities; 

• PSOs would use a combination of 

equipment to perform marine mammal 

observations and to verify the required 

monitoring distance from the project 

site, which may include 7 by 50 

binoculars, 20x/40x tripod mounted 

binoculars, 25 by 150 ‘‘big eye’’ tripod 

mounted binoculars, and theodolites; 

• PSOs must record all observations 

of marine mammals, regardless of 

distance from the pile being driven. 

PSOs shall document any behavioral 

reactions in concert with distance from 

piles being driven or removed; 

PSOs must have the following 

additional qualifications: 

• Ability to conduct field 

observations and collect data according 

to assigned protocols; 

• Experience or training in the field 

identification of marine mammals, 

including the identification of 

behaviors; 

• Sufficient training, orientation, or 

experience with the construction 

operation to provide for personal safety 

during observations; 

• Writing skills sufficient to record 

required information including but not 

limited to the number and species of 

marine mammals observed; dates and 

times when in-water construction 

activities were conducted; dates, times, 

and reason for implementation of 

mitigation (or why mitigation was not 

implemented when required); and 

marine mammal behavior; and 

• Ability to communicate orally, by 

radio or in person, with project 

personnel to provide real-time 

information on marine mammals 

observed in the area as necessary. 

Reporting 

NMFS would require the POA to 

submit interim weekly monitoring 

reports within 14 calendar days after the 

conclusion of each calendar week (that 

include raw electronic data sheets) 

during the CTR construction seasons, 

including for weeks during which no inwater work occurred (an email 

notification for weeks with no in-water 

work would be sufficient). These reports 

must include a summary of marine 

mammal species observed and 

behavioral observations, mitigation 

actions implemented, construction 

delays, and construction work 

completed. They also must include an 

assessment of the amount of 

construction remaining to be completed 

(i.e., the number of estimated hours of 

work remaining), in addition to the 

number of CIBWs observed within 

estimated harassment zones to date for 

the current construction year. 

NMFS would also require the POA to 

submit annual reports after the end of 

each construction season and a 

comprehensive final report following 

the conclusion of year 5 construction 

activities. Draft annual marine mammal 

monitoring reports must be submitted to 

NMFS within 90 days after the 

completion of each construction season 

or 60 days prior to a requested date of 

issuance of any future incidental take 

authorization for projects at the same 

location, whichever comes first. Annual 

reports must detail the monitoring 

protocol and summarize the data 

recorded during monitoring, and 

associated PSO data sheets in electronic 

tabular format. Specifically, the reports 

must include: 

• Dates and times (begin and end) of 

all marine mammal monitoring; 

• Construction activities occurring 

during each daily observation period, 

including the number and type of piles 

driven or removed and by what method 

(i.e., impact or vibratory, the total 

equipment duration for vibratory 

installation and removal, and the total 

number of strikes for each pile during 

impact driving); 

• PSO locations during marine 

mammal monitoring; 

• Environmental conditions during 

monitoring periods (at beginning and 

end of PSO shift and whenever 

conditions change significantly), 

including Beaufort sea state and any 

other relevant weather conditions 

including cloud cover, fog, sun glare, 

and overall visibility to the horizon, and 

estimated observable distance; 

• Upon observation of a marine 

mammal, the following information: 

name of PSO who sighted the animal(s) 

and PSO location and activity at time of 

sighting; time of sighting; identification 

of the animal(s) (e.g., genus/species, 

lowest possible taxonomic level, or 

unidentified), PSO confidence in 

identification, and the composition of 

the group if there is a mix of species; 

distance and bearing of each marine 

mammal observed relative to the pile 

being driven for each sighting (if pile 

driving was occurring at time of 

sighting); estimated number of animals 

(minimum, maximum, and best 

estimate); estimated number of animals 

by cohort (adults, juveniles, neonates, 

group composition, sex class, etc.); 

animal’s closest point of approach and 

estimated time spent within the 

harassment zone; group spread and 

formation (for CIBWs only; see ethogram 

in Appendix B of the POA’s 

application); description of any marine 

mammal behavioral observations (e.g., 

observed behaviors such as feeding or 

traveling), including an assessment of 

behavioral responses that may have 

resulted from the activity (e.g., no 

response or changes in behavioral state 

such as ceasing feeding, changing 

direction, flushing, or breaching); 

• Number of marine mammals 

detected within the harassment zones, 

by species; 

• Detailed information about any 

implementation of mitigation action 

(e.g., shutdowns and delays), a 

description of specific actions that 

ensued, and resulting changes in 

behavior of the animal(s), if any; 

If no comments are received from 

NMFS within 30 days, the draft annual 

or comprehensive reports would 

constitute the final reports. If comments 

are received, a final report addressing 

NMFS comments must be submitted 

within 30 days after receipt of 

comments. 

Reporting Injured or Dead Marine 

Mammals 

In the event that personnel involved 

in the construction activities discover 

an injured or dead marine mammal, the 

POA must immediately cease the 

specified activities and report the 

incident to the Office of Protected 

Resources, NMFS 


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(PR.ITP.MonitoringReports@noaa.gov, 

ITP.hotchkin@noaa.gov) and to the 

Alaska Regional Stranding Coordinator 

as soon as feasible. If the death or injury 

was clearly caused by the specified 

activity, the POA must immediately 

cease the specified activities until 

NMFS is able to review the 

circumstances of the incident and 

determine what, if any, additional 

measures are appropriate to ensure 

compliance with the terms of the IHA. 

The POA must not resume their 

activities until notified by NMFS. The 

report must include the following 

information: 

• Time, date, and location (latitude 

and longitude) of the first discovery 

(and updated location information if 

known and applicable); 

• Species identification (if known) or 

description of the animal(s) involved; 

• Condition of the animal(s) 

(including carcass condition if the 

animal is dead); 

• Observed behaviors of the 

animal(s), if alive; 

• If available, photographs or video 

footage of the animal(s); and 

• General circumstances under which 

the animal was discovered. 

Adaptive Management 

These proposed regulations governing 

the take of marine mammals incidental 

to POA’s CTR construction activities 

contain an adaptive management 

component. Our understanding of the 

effects of pile driving and other coastal 

construction activities (e.g., acoustic 

stressors) on marine mammals 

continues to evolve, which makes the 

inclusion of an adaptive management 

component both valuable and necessary 

within the context of 5-year regulations. 

The monitoring and reporting 

requirements are associated with 

information that helps us to better 

understand the impacts of the project’s 

activities on marine mammals and 

informs our consideration of whether 

any changes to mitigation and 

monitoring are appropriate. The use of 

adaptive management allows NMFS to 

consider new information from different 

sources to determine (with input from 

the POA regarding practicability) if such 

modifications will have a reasonable 

likelihood of more effectively 

accomplishing the goals of the 

measures. 

The following are some of the 

possible sources of applicable data to be 

considered through the adaptive 

management process: (1) results from 

monitoring reports, including the 

weekly, situational, and annual reports 

required; (2) results from research on 

marine mammals, noise impacts, or 

other related topics; and (3) any 

information which reveals that marine 

mammals may have been taken in a 

manner, extent, or number not 

authorized by these regulations or LOAs 

issued pursuant to these regulations. 

Adaptive management decisions may be 

made at any time, as new information 

warrants it. 

Negligible Impact Analysis and 

Determination 

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). A negligible impact 

finding is based on the lack of likely 

adverse effects on annual rates of 

recruitment or survival (i.e., populationlevel effects). An estimate of the number 

of takes alone is not enough information 

on which to base an impact 

determination. In addition to 

considering estimates of the number of 

marine mammals that might be ‘‘taken’’ 

through harassment, NMFS considers 

other factors, such as the likely nature 

of any impacts or responses (e.g., 

intensity, duration), the context of any 

impacts or responses (e.g., critical 

reproductive time or location, foraging 

impacts affecting energetics), as well as 

effects on habitat, and the likely 

effectiveness of the mitigation. We also 

assess the number, intensity, and 

context of estimated takes by evaluating 

this information relative to population 

status. Consistent with the 1989 

preamble for NMFS’ implementing 

regulations (54 FR 40338, September 29, 

1989), the impacts from other past and 

ongoing anthropogenic activities are 

incorporated into this analysis via their 

impacts on the baseline (e.g., as 

reflected in the regulatory status of the 

species, population size and growth rate 

where known, ongoing sources of 

human-caused mortality, or ambient 

noise levels). 

To avoid repetition, this introductory 

discussion of our analysis applies to all 

the species listed in table 25 except 

CIBWs given that many of the 

anticipated effects of this project on 

different marine mammal stocks are 

expected to be relatively similar in 

nature. For CIBWs, there are meaningful 

differences in anticipated individual 

responses to activities, impact of 

expected take on the population, or 

impacts on habitat; therefore, we 

provide a separate detailed analysis for 

CIBWs following the analysis for other 

species for which we propose to 

authorize incidental take. 

NMFS has identified key factors 

which may be employed to assess the 

level of analysis necessary to conclude 

whether potential impacts associated 

with a specified activity should be 

considered negligible. These include, 

but are not limited to, the type and 

magnitude of taking, the amount and 

importance of the available habitat for 

the species or stock that is affected, the 

duration of the anticipated effect to the 

species or stock, and the status of the 

species or stock. The potential effects of 

the specified activities on gray whales, 

humpback whales, killer whales, harbor 

porpoises, Steller sea lions, and harbor 

seals are discussed below. Some of these 

factors also apply to CIBWs; however, a 

more detailed analysis for CIBWs is 

provided in a separate subsection 

below. 

Species Other than CIBW. Pile driving 

associated with the project, as outlined 

previously, has the potential to disturb 

or displace marine mammals. 

Specifically, the specified activities may 

result in take, in the form of Level B 

harassment and, for some species, Level 

A harassment, from underwater sounds 

generated by pile driving. Potential 

takes could occur if marine mammals 

are present in zones ensonified above 

the thresholds for Level B harassment or 

Level A harassment, identified above, 

while activities are underway. 

The POA’s proposed activities and 

associated impacts would occur within 

a limited, confined area of the stocks’ 

range (other than CIBW). The work 

would occur in the vicinity of the CTR 

site, and sound from the proposed 

activities would be blocked by the 

coastline along Knik Arm along the 

eastern boundaries of the site and for 

those harassment isopleths that extend 

more than 3,000 m, directly across the 

Arm along the western shoreline (see 

figures 6–10 and 6–11 in the POA’s 

application)). The intensity and 

duration of take by Level A and Level 

B harassment would be minimized 

through use of mitigation measures 

described herein. Further, the number of 

takes proposed to be authorized is small 

when compared to stock abundance (see 

table 25). In addition, NMFS does not 

anticipate that serious injury or 

mortality will occur as a result of the 

POA’s planned activity given the nature 

of the activity, even in the absence of 

required mitigation. 

Exposures to elevated sound levels 

produced during pile driving may cause 

behavioral disturbance of some 

individuals. Behavioral responses of 

marine mammals to pile driving at the 

proposed project site are expected to be 

mild, short term, and temporary. Effects 

on individuals that are taken by Level 


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B harassment, as enumerated in the 

Estimated Take section, on the basis of 

reports in the literature as well as 

monitoring from other similar activities 

at the POA and elsewhere, will likely be 

limited to reactions such as increased 

swimming speeds, increased surfacing 

time, or decreased foraging if such 

activity were occurring (e.g., Ridgway et 

al., 1997; Nowacek et al., 2007; Thorson 

and Reyff, 2006; Kendall and Cornick, 

2015; Goldbogen et al., 2013b; Blair et 

al., 2016; Wisniewska et al., 2018; 

Piwetz et al., 2021). Marine mammals 

within the Level B harassment zones 

may not show any visual cues they are 

disturbed by activities or they could 

become alert, avoid the area, leave the 

area, or display other mild responses 

that are not visually observable such as 

exhibiting increased stress levels (e.g., 

Rolland et al. 2012; Lusseau, 2005; 

Bejder et al., 2006; Rako et al., 2013; 

Pirotta et al., 2015b; Pe ́rez-Jorge et al., 

2016). They may also exhibit increased 

vocalization rates, louder vocalizations, 

alterations in the spectral features of 

vocalizations, or a cessation of 

communication signals (Hotchkin and 

Parks 2013). However, as described in 

the Potential Effects of Specified 

Activities on Marine Mammals and 

Their Habitat section of this proposed 

rule, marine mammals, except CIBWs, 

observed within Level A and Level B 

harassment zones related to recent POA 

construction activities have not shown 

any acute, visually observable reactions 

to pile driving activities that have 

occurred during the PCT and SFD 

projects (61N Environmental, 2021, 

2022a, 2022b). 

Some of the species present in the 

region will only be present temporarily 

based on seasonal patterns or during 

transit between other habitats. These 

temporarily present species will be 

exposed to even smaller periods of 

noise-generating activity, further 

decreasing the impacts. Most likely, 

individual animals will simply move 

away from the sound source and be 

temporarily displaced from the area. 

Takes may also occur during important 

feeding times. The project area though 

represents a small portion of available 

foraging habitat and impacts on marine 

mammal feeding for all species is 

expected to be minimal. 

The activities analyzed here are 

similar to numerous other construction 

activities conducted in Southern Alaska 

(e.g., 86 FR 43190, August 6, 2021; 87 

FR 15387, March 18, 2022), including 

the PCT and SFD projects within Upper 

Knik Arm (85 FR 19294, April 6, 2020; 

86 FR 50057, September 7, 2021, 

respectively) which have taken place 

with no known long-term adverse 

consequences from behavioral 

harassment. Any potential reactions and 

behavioral changes are expected to 

subside quickly when the exposures 

cease, and therefore, no long-term 

adverse consequences are expected (e.g., 

Graham et al., 2017). While there are no 

long-term peer-reviewed studies of 

marine mammal habitat use at the POA, 

studies from other areas indicate that 

most marine mammals would be 

expected to have responses on the order 

of hours to days. For example, harbor 

porpoises returned to a construction 

area between pile-driving events within 

several days during the construction of 

offshore wind turbines near Denmark 

(Carstensen et al., 2006). The intensity 

of Level B harassment events would be 

minimized through use of mitigation 

measures described herein, which were 

not quantitatively factored into the take 

estimates. The POA would use PSOs 

stationed strategically to increase 

detectability of marine mammals during 

in-water construction activities, 

enabling a high rate of success in 

implementation of shutdowns to avoid 

or minimize injury for most species. 

Further, given the absence of any major 

rookeries and haulouts within the 

estimated harassment zones, we assume 

that potential takes by Level B 

harassment would have an 

inconsequential short-term effect on 

individuals and would not result in 

population-level impacts. 

As stated in the mitigation section, 

the POA will implement shutdown 

zones (table 26) that equal or exceed the 

Level A harassment isopleths (table 16) 

for most vibratory pile driving and 

maximize practicability for shutdowns 

during impact pile driving. Take by 

Level A harassment is proposed for 

authorization for some species (gray 

whales, humpback whales, killer 

whales, harbor seals, Steller sea lions, 

and harbor porpoises) to account for the 

large Level A harassment zones from 

impact driving and the potential that an 

animal could enter and remain 

unobserved within the estimated Level 

A harassment zone for a duration long 

enough to incur auditory injury. Any 

take by Level A harassment is expected 

to arise from, at most, a small degree of 

auditory injury because animals would 

need to be exposed to higher levels and/ 

or longer duration than are expected to 

occur here in order to incur any more 

than a small degree of auditory injury. 

Due to the levels and durations of 

likely exposure, animals that experience 

auditory injury will likely only receive 

slight injury (i.e., minor degradation of 

hearing capabilities within regions of 

hearing that align most completely with 

the frequency range of the energy 

produced by POA’s proposed in-water 

construction activities (i.e., the lowfrequency region below 2 kHz)), not 

severe hearing impairment or 

impairment in the ranges of greatest 

hearing sensitivity. If hearing 

impairment does occur, it is most likely 

that the affected animal will lose a few 

dBs in its hearing sensitivity, which, in 

most cases, is not likely to meaningfully 

affect its ability to forage and 

communicate with conspecifics. There 

are no data to suggest that a single 

instance in which an animal incurs 

auditory injury (or TTS) would result in 

impacts to reproduction or survival. If 

auditory injury were to occur, it would 

be minor and unlikely to affect more 

than a few individuals. Additionally, 

and as noted previously, some subset of 

the individuals that are behaviorally 

harassed could also simultaneously 

incur some small degree of TTS for a 

short duration of time. Because of the 

small degree anticipated, though, any 

auditory injury or TTS potentially 

incurred here is not expected to 

adversely impact individual fitness, let 

alone annual rates of recruitment or 

survival for the affected species or 

stocks. 

Repeated, sequential exposure to pile 

driving noise over a long duration could 

result in more severe impacts to 

individuals that could affect a 

population (via sustained or repeated 

disruption of important behaviors such 

as feeding, resting, traveling, and 

socializing; Southall et al., 2007). 

Alternatively, marine mammals exposed 

to repetitious construction sounds may 

become habituated, desensitized, or 

tolerant after initial exposure to these 

sounds (reviewed by Richardson et al., 

1995; Southall et al., 2007). However, 

given the relatively low abundance of 

marine mammals other than CIBWs in 

Knik Arm compared to the stock sizes 

(table 25), population-level impacts are 

not anticipated. The absence of any 

pinniped haulouts or other known nonCIBW home-ranges in the proposed 

action area further decreases the 

likelihood of population-level impacts. 

The CTR project is also not expected 

to have significant adverse effects on 

any marine mammal habitat. The project 

activities would occur mostly within the 

same footprint as existing marine 

infrastructure; the new T1 and T2 

would extend approximately 140 ft (47- 

m) seaward of the existing terminals. 

The long-term impact on marine 

mammals associated with CTR would be 

a small permanent decrease in lowquality potential habitat because of the 

expanded footprint of the new cargo 

terminals T1 and T2. Installation and 

removal of in-water piles would be 


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temporary and intermittent, and the 

increased footprint of the facilities 

would destroy only a small amount of 

low-quality habitat, which currently 

experiences high levels of 

anthropogenic activity. Impacts to the 

immediate substrate are anticipated, but 

these would be limited to minor, 

temporary suspension of sediments, 

which could impact water quality and 

visibility for a short amount of time but 

which would not be expected to have 

any effects on individual marine 

mammals. Further, there are no known 

BIAs near the project zone, except for 

CIBWs, that will be impacted by the 

POA’s planned activities. 

Impacts to marine mammal prey 

species are also expected to be minor 

and temporary and to have, at most, 

short-term effects on foraging of 

individual marine mammals and likely 

no effect on the populations of marine 

mammals as a whole. Overall, the area 

impacted by the CTR project is very 

small compared to the available 

surrounding habitat and does not 

include habitat of particular importance. 

The most likely impact to prey would be 

temporary behavioral avoidance of the 

immediate area. During construction 

activities, it is expected that some fish 

and marine mammals would 

temporarily leave the area of 

disturbance, thus impacting marine 

mammals’ foraging opportunities in a 

limited portion of their foraging range. 

But, because of the relatively small area 

of the habitat that may be affected and 

lack of any habitat of particular 

importance, the impacts to marine 

mammal habitat are not expected to 

cause significant or long-term negative 

consequences. 

In summary, the following factors 

primarily support our preliminary 

negligible impact determinations for the 

affected stocks of gray whales, 

humpback whales, killer whales, harbor 

porpoises, Steller sea lions, and harbor 

seals: 

• No takes by mortality or serious 

injury are anticipated or proposed for 

authorization; 

• Any acoustic impacts to marine 

mammal habitat from pile driving are 

expected to be temporary and minimal; 

• Take would not occur in places 

and/or times where take would be more 

likely to accrue to impacts on 

reproduction or survival, such as within 

ESA-designated or proposed critical 

habitat, BIAs, or other habitats critical to 

recruitment or survival (e.g., rookery); 

• The project area represents a very 

small portion of the available foraging 

area for all potentially impacted marine 

mammal species and does not contain 

any habitat of particular importance; 

• Take will only occur within upper 

Cook Inlet—a limited, confined area of 

any given stock’s home range; 

• Monitoring reports from similar 

work in Knik Arm have documented 

little to no observable effect on 

individuals of the same species 

impacted by the specified activities; 

• The required mitigation measures 

(i.e., soft starts, pre-clearance 

monitoring, shutdown zones, bubble 

curtains) are expected to be effective in 

reducing the effects of the specified 

activity by minimizing the numbers of 

marine mammals exposed to injurious 

levels of sound and by ensuring that any 

take by Level A harassment is, at most, 

a small degree of AUD INJ and of a 

lower degree that would not impact the 

fitness of any animals; and 

• The intensity of anticipated takes 

by Level B harassment is low for all 

stocks consisting of, at worst, temporary 

modifications in behavior, and would 

not be of a duration or intensity 

expected to result in impacts on 

reproduction or survival. 

Cook Inlet Beluga Whales. For CIBWs, 

we further discuss our negligible impact 

findings in the context of potential 

impacts to this endangered stock based 

on our evaluation of the take proposed 

for authorization (table 25). 

As described in the Recovery Plan for 

the CIBW (NMFS, 2016b), NMFS 

determined the following physical or 

biological features are essential to the 

conservation of this species: (1) 

Intertidal and subtidal waters of Cook 

Inlet with depths less than 9 m mean 

lower low water and within 8 km of 

high and medium flow anadromous fish 

streams; (2) Primary prey species 

consisting of four species of Pacific 

salmon (Chinook, sockeye, chum, and 

coho), Pacific eulachon, Pacific cod, 

walleye pollock, saffron cod, and 

yellowfin sole, (3) Waters free of toxins 

or other agents of a type and amount 

harmful to CIBWs, (4) Unrestricted 

passage within or between the critical 

habitat areas, and (5) Waters with inwater noise below levels resulting in the 

abandonment of critical habitat areas by 

CIBWs. The CTR project will not impact 

essential features 1–3 listed above. All 

construction will be done in a manner 

implementing best management 

practices to preserve water quality, and 

no work will occur around creek 

mouths or river systems leading to prey 

abundance reductions. In addition, no 

physical structures will restrict passage; 

however, impacts to the acoustic habitat 

are relevant and discussed here. 

Monitoring data from the POA suggest 

pile driving does not discourage CIBWs 

from entering Knik Arm and traveling to 

critical foraging grounds such as those 

around Eagle Bay (e.g., 61N 

Environmental, 2021, 2022a, 2022b; 

Easley-Appleyard and Leonard, 2022). 

As described in greater detail in the 

Potential Effects of Specified Activities 

on Marine Mammals and Their Habitat 

section of this notice, sighting rates 

were not different in the presence or 

absence of pile driving (Kendall and 

Cornick, 2015). In addition, large 

numbers of CIBWs have continued to 

forage in portions of Knik Arm and pass 

through the area near the POA during 

pile driving projects over the past two 

decades (Funk et al., 2005; PrevelRamos et al., 2006; Markowitz and 

McGuire, 2007; Cornick and SaxonKendall, 2008, 2009; ICRC, 2009, 2010, 

2011, 2012; Cornick et al., 2010, 2011; 

Cornick and Pinney, 2011; Cornick and 

Seagars, 2016; POA, 2019), including 

during the recent PCT and SFD 

construction projects (61N 

Environmental, 2021, 2022a, 2022b; 

Easley-Appleyard and Leonard, 2022). 

These findings are not surprising as 

food is a strong motivation for marine 

mammals, and preying on seasonal 

anadromous fish runs in Eagle and Knik 

Rivers necessitates CIBWs passing the 

POA. As described in Forney et al. 

(2017), animals typically favor 

particular areas because of their 

importance for survival (e.g., feeding or 

breeding) and leaving may have 

significant costs to fitness (reduced 

foraging success, increased predation 

risk, increased exposure to other 

anthropogenic threats). Consequently, 

animals may be highly motivated to 

maintain foraging behavior in historical 

foraging areas despite negative impacts 

(e.g., Rolland et al., 2012). 

Previous monitoring data indicates 

CIBWs may be responding to pile 

driving noise but not through 

abandonment of primary foraging areas 

north of the port. Instead, they may 

travel faster past the POA, more quietly, 

and in smaller, tighter groups (Kendall 

and Cornick, 2015; 61N Environmental, 

2021, 2022a, 2022b). CIBW presence at 

the POA has been extensively 

monitored during pile driving projects 

over the last several years, with data 

gathered during active driving activities 

and during periods of no construction 

noise. CIBWs are regularly observed at 

the POA even during active pile driving 

as discussed below. 

During PCT and SFD construction 

monitoring, little variability was evident 

in the behaviors recorded from month to 

month or between sightings that 

coincided with in-water pile installation 

and removal and those that did not (61N 

Environmental, 2021, 2022a, 2022b; 

Easley-Appleyard and Leonard, 2022). 

Of the 386 CIBWs groups sighted during 


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PCT and SFD construction monitoring, 

10 groups were observed during or 

within minutes of in-water impact pile 

installation and 56 groups were 

observed during or within minutes of 

vibratory pile installation or removal 

(61N Environmental, 2021, 2022a, 

2022b). In general, CIBWs were more 

likely to display no reaction or to 

continue to move towards the PCT or 

SFD during pile installation and 

removal. In the situations during which 

CIBWs showed a possible reaction (6 

groups during impact driving and 13 

groups during vibratory driving), CIBWs 

were observed either moving away 

immediately after the pile driving 

activities started or were observed 

increasing their rate of travel. 

NMFS funded a visual marine 

mammal monitoring project in 2021 

(described in the Potential Effects of 

Specified Activities on Marine 

Mammals and Their Habitat) to 

supplement sighting data collected by 

the POA monitoring program during 

non-pile driving days in order to further 

evaluate the impacts of anthropogenic 

activities on CIBWs (Easley-Appleyard 

and Leonard, 2022). Preliminary results 

suggest that group size ranged from 1 to 

34 whales, with an average of 3 to 5.6, 

depending on the month. September 

had the highest sighting rate with 4.08 

whales per hour, followed by October 

and August (3.46 and 3.41, 

respectively). Traveling was recorded as 

the primary behavior for 80 percent of 

the group sightings and milling was the 

secondary behavior most often recorded. 

Sighting duration varied from a single 

surfacing lasting less than 1 minute to 

380 minutes. Preliminary findings 

suggest these results are consistent with 

the results from the POA’s PCT and SFD 

monitoring efforts. For example, group 

sizes ranged from 2.38 to 4.32 

depending on the month and the highest 

sighting rate was observed in September 

(1.75). In addition, traveling was the 

predominant behavior observed for all 

months and categories of construction 

activity (i.e., no pile driving, before pile 

driving, during pile driving, between 

pile driving, or after pile driving), being 

recorded as the primary behavior for 86 

percent of all sightings, and either the 

primary or secondary behavior for 95 

percent of sightings. 

Easley-Appleyard and Leonard (2022) 

also asked PSOs to complete a 

questionnaire post-monitoring that 

provided NMFS with qualitative data 

regarding CIBW behavior during 

observations. Specifically during pile 

driving events, the PSOs noted that 

CIBW behaviors varied; however, 

multiple PSOs noted seeing behavioral 

changes specifically during impact pile 

driving and not during vibratory pile 

driving. CIBWs were observed 

sometimes changing direction, turning 

around, or changing speed during 

impact pile driving, whereas there were 

numerous instances where CIBWs were 

seen traveling directly towards the POA 

during vibratory pile driving before 

entering the Level B harassment zone 

(61N Environmental, 2021, 2022a, 

2022b). The PSOs also reported that it 

seemed more likely for CIBWs to show 

more cryptic behavior during active 

impact and vibratory pile driving (e.g., 

surfacing infrequently and without clear 

direction), though this seemed to vary 

across months (Easley-Appleyard and 

Leonard, 2022). 

We anticipate that disturbance to 

CIBWs will manifest in the same 

manner when they are exposed to noise 

during the CTR project: whales would 

move quickly and silently through the 

area in more cohesive groups. Exposure 

to elevated noise levels during transit 

past the POA is not expected to have 

adverse effects on reproduction or 

survival as the whales continue to 

access critical foraging grounds north of 

the POA. Potential behavioral reactions 

that have been observed, including 

changes in group distribution and 

speed, may help to mitigate the 

potential for any contraction of 

communication space for a group. 

CIBWs are not expected to abandon 

entering or exiting Knik Arm as this is 

not evident based on monitoring data 

from the past two decades of work at 

POA (e.g., Funk et al., 2005; PrevelRamos et al., 2006; Markowitz and 

McGuire, 2007; Cornick and SaxonKendall, 2008, 2009; ICRC, 2009, 2010, 

2011, 2012; Cornick et al., 2010, 2011; 

Cornick and Pinney, 2011; Cornick and 

Seagars, 2016; POA, 2019; Kendall and 

Cornick, 2015; 61N Environmental, 

2021, 2022a, 2022b; Easley-Appleyard 

and Leonard, 2022). Finally, as 

described previously, both telemetry 

(tagging) and acoustic data suggest 

CIBWs likely stay in upper Knik Arm 

(i.e., north of the CTR project site) for 

several days or weeks before exiting 

Knik Arm. Specifically, a CIBW 

instrumented with a satellite link time/ 

depth recorder entered Knik Arm on 

August 18, 1999 and remained in Eagle 

Bay until September 12, 1999 (Ferrero et 

al., 2000). Further, a recent detailed reanalysis of the satellite telemetry data 

confirms how several tagged whales 

exhibited this same movement pattern: 

whales entered Knik Arm and remained 

there for several days before exiting 

through lower Knik Arm (Shelden et al., 

2018). This longer-term use of upper 

Knik Arm will avoid repetitive 

exposures from pile driving noise. 

It is possible that exposure to pile 

driving at the POA could result in 

CIBWs avoiding Knik Arm and thereby 

not accessing the productive foraging 

grounds north of POA such as Eagle 

River flats thus, impacting essential 

feature number five of the designated 

Critical Habitat. The data previously 

presented demonstrate CIBWs are not 

abandoning the area (i.e., continue to 

access the waters of northern Knik Arm 

during construction activities). 

Additionally, results of an expert 

elicitation (EE) at a 2016 workshop, 

which predicted the impacts of noise on 

CIBW survival and reproduction given 

lost foraging opportunities, helped to 

inform our assessment of impacts on 

this stock. The 2016 EE workshop used 

conceptual models of an interim 

population consequences of disturbance 

(PCoD) for marine mammals (NRC, 

2005; New et al., 2014; Tollit et al., 

2016) to help in understanding how 

noise-related stressors might affect vital 

rates (survival, birth rate and growth) for 

CIBW (King et al., 2015). NMFS (2016b) 

suggests that the main direct effects of 

noise on CIBW are likely to be through 

masking of vocalizations used for 

communication and prey location and 

habitat degradation. The 2016 workshop 

on CIBWs was specifically designed to 

provide regulators with a tool to help 

understand whether chronic and acute 

anthropogenic noise from various 

sources and projects are likely to be 

limiting recovery of the CIBW 

population. The full report can be found 

at https://www.smruconsulting.com/ 

publications/with a summary of the 

expert elicitation portion of the 

workshop below. 

For each of the noise effect 

mechanisms chosen for EE, the experts 

provided a set of parameters and values 

that determined the forms of a 

relationship between the number of 

‘‘days of disturbance’’ (defined as any 

day on which an animal loses the ability 

to forage for at least one tidal cycle (i.e., 

it forgoes 50–100 percent of its energy 

intake on that day)) a female CIBW 

experiences in a particular period and 

the effect of that disturbance on her 

energy reserves. Examples included the 

number of disturbed days during the 

months of April, May, and June that 

would be predicted to reduce the energy 

reserves of a pregnant CIBW to such a 

level that she is certain to terminate the 

pregnancy or abandon the calf soon after 

birth; the number of disturbed days of 

from April to September required to 

reduce the energy reserves of a lactating 

CIBW to a level where she is certain to 

abandon her calf; and the threshold 


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disturbed days where a female fails to 

gain sufficient energy by the end of 

summer to maintain themselves and 

their calves during the subsequent 

winter. 

Overall, median values ranged from 

16 to 69 days of disturbance depending 

on the question. However, a ‘‘day of 

disturbance’’ considered in the context 

of the report is notably more severe than 

the Level B harassment expected to 

result from these activities, which as 

described is expected to be comprised 

predominantly of temporary 

modifications in the behavior of 

individual CIBWs (e.g., faster swim 

speeds, more cohesive group structure, 

decreased sighting durations, cessation 

of vocalizations) based on the large body 

of observational data available from 

previous monitoring efforts at the Port. 

Also, NMFS proposes to authorize an 

annual maximum of 90 instances of 

takes, with the instances representing 

disturbance events within a day. This 

means that either 90 different individual 

CIBWs are disturbed on no more than 1 

day each per year or some lesser number 

of individuals may be disturbed on 

more than 1 day but with the product 

of individuals and days not exceeding 

90. Given the overall estimated take, it 

is unlikely that any one CIBW will be 

disturbed on more than a few days. 

Further, the mitigation measures NMFS 

has proposed for the CTR project are 

designed to avoid the potential that any 

animal will lose the ability to forage for 

one or more tidal cycles should they be 

foraging in the proposed action area, 

which is not known to be a particularly 

important feeding area for CIBWs. 

While Level B harassment (behavioral 

disturbance) is proposed to be 

authorized, the POA’s mitigation 

measures will limit the severity of the 

effects of that Level B harassment to 

behavioral changes such as increased 

swim speeds, tighter group formations, 

and cessation of vocalizations, not the 

loss of foraging capabilities. Regardless, 

this elicitation recognized that pregnant 

or lactating females and calves are 

inherently more at risk than other 

animals, such as males. Given that 

individuals in potentially vulnerable 

life stages, such as pregnancy, cannot be 

identified by visual observers, pile 

driving would be shut down for all 

CIBWs to be protective of potentially 

vulnerable individuals, and to avoid 

more severe behavioral reactions. 

NMFS proposes required mitigation 

measures to minimize exposure to 

CIBWs, specifically, shutting down pile 

driving should a CIBW approach or 

enter the Level B harassment zone. 

These measures are designed to reduce 

the intensity and duration of potential 

harassment CIBWs experience during 

the POA’s construction activities. 

Additionally, the proposed mitigation 

measures would help to ensure CIBWs 

will not experience degradation of 

acoustic habitat approaching the 

threshold set in the Critical Habitat 

designation (i.e., in-water noise at levels 

resulting in the abandonment of habitat 

by CIBWs). The location of the PSOs 

would allow for detection of CIBWs and 

behavioral observations prior to CIBWs 

entering the Level B harassment zone. 

Additionally, NMFS proposes to 

require use of a bubble curtain for all 

permanent piles in waters deeper than 

3 m in all months and for all piles 

(permanent or temporary) installed or 

extracted in waters deeper than 3 m 

during the months of August–October 

when CIBWs are present in higher 

numbers in Knik Arm. This measure is 

designed to reduce the amount of noise 

exposure at frequencies to which CIBWs 

are more sensitive (<100 Hz) during 

vibratory pile driving and to reduce 

overall sound levels during impact 

driving. During impact driving, the POA 

must implement soft starts, which 

ideally allows animals to leave a 

disturbed area before the full-power 

driving commences (Tougaard et al., 

2012). Although NMFS does not 

anticipate CIBWs will abandon entering 

Knik Arm in the presence of pile 

driving, PSOs will be integral to 

identifying if CIBWs are potentially 

altering pathways they would otherwise 

take in the absence of pile driving. 

Finally, take by mortality, serious 

injury, or Level A harassment of CIBWs 

is not anticipated or proposed to be 

authorized. 

In summary, the following factors 

primarily support our preliminary 

determination that the impacts resulting 

from this activity are not expected to 

adversely affect the CIBWs through 

effects on annual rates of recruitment or 

survival: 

• No mortality, serious injury, or 

Level A harassment is anticipated or 

proposed to be authorized; 

• Any acoustic impacts to marine 

mammal habitat from pile driving are 

expected to be temporary and minimal; 

• The required mitigation measures 

(i.e., soft starts, pre-clearance 

monitoring, shutdown zones, bubble 

curtains) are expected to be effective in 

reducing the effects of the specified 

activity by ensuring that no CIBWs are 

exposed to noise at injurious levels (i.e., 

Level A harassment); 

• The intensity of anticipated takes 

by Level B harassment is low, consisting 

of, at worst, temporary modifications in 

behavior, and would not be of a 

duration or intensity expected to result 

in impacts on reproduction or survival. 

• The area of exposure would be 

limited to habitat primarily used as a 

travel corridor. Data demonstrates Level 

B harassment of CIBWs typically 

manifests as increased swim speeds past 

the POA, tighter group formations, and 

cessation of vocalizations, rather than 

through habitat abandonment; 

• No critical foraging grounds (e.g., 

Eagle Bay, Eagle River, Susitna Delta) 

would be affected by pile driving; and 

• While animals could be harassed 

more than once, exposures are not likely 

to exceed more than a few per year for 

any given individual and are not 

expected to occur on sequential days; 

thereby decreasing the potential severity 

and interaction between harassment 

events for affected individuals. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat and taking into 

consideration the implementation of the 

required monitoring and mitigation 

measures, NMFS preliminarily finds 

that the proposed marine mammal take 

from the specified activity will have a 

negligible impact on all affected marine 

mammal species or stocks. 

Small Numbers 

As noted previously, only incidental 

take of small numbers of marine 

mammals may be authorized under 

sections 101(a)(5)(A) and (D) of the 

MMPA for specified activities other 

than military readiness activities. The 

MMPA does not define small numbers 

and so, in practice, where estimated 

numbers are available, NMFS compares 

the maximum estimated number of 

individuals annually taken to the most 

appropriate estimation of abundance of 

the relevant species or stock in our 

determination of whether an 

authorization is limited to small 

numbers of marine mammals. When the 

predicted maximum annual number of 

individuals to be taken is fewer than 

one-third of the species or stock 

abundance, the take is considered to be 

of small numbers. Additionally, other 

qualitative factors may be considered in 

the analysis, such as the temporal or 

spatial scale of the activities. 

For all stocks, except for the MexicoNorth Pacific stock of humpback whales 

whose abundance estimate is unknown, 

the proposed number of takes is less 

than one-third of the best available 

population abundance estimate (i.e., 

less than 1 percent for 6 stocks; less 

than 2 percent for 1 stock; and less than 

27.2 percent for CIBWs; see table 25). 

The maximum annual number of 

animals proposed for authorization to be 


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taken from these stocks would be 

considered small relative to the relevant 

stock’s abundances even if each 

estimated take occurred to a new 

individual. The number of takes 

authorized likely represents smaller 

numbers of individual harbor seals and 

Steller sea lions. Harbor seals tend to 

concentrate near Ship Creek and have 

small home ranges. It is possible that a 

single individual harbor seal may linger 

near the POA, especially near Ship 

Creek and be counted multiple times 

each day as it moves around and 

resurfaces in different locations. 

Previous Steller sea lion sightings 

identified that if a Steller sea lion is 

within Knik Arm, it is likely lingering 

to forage on salmon or eulachon runs 

and may be present for several days. 

Therefore, the number of takes 

authorized likely represents repeat 

exposures to the same animals in certain 

circumstances. For all species, PSOs 

would count individuals as separate 

unless they can be individually 

identified. 

Abundance estimates for the MexicoNorth Pacific stock of humpback whales 

are based upon data collected more than 

8 years ago, and therefore, current 

estimates are considered unknown 

(Young et al., 2023). The most recent 

minimum population estimates (NMIN) 

for this population include an estimate 

of 2,241 individuals between 2003 and 

2006 (Martinez-Aguilar, 2011) and 766 

individuals between 2004 and 2006 

(Wade, 2021). NMFS’ Guidelines for 

Assessing Marine Mammal Stocks 

suggest that the NMIN estimate of the 

stock should be adjusted to account for 

potential abundance changes that may 

have occurred since the last survey and 

provide reasonable assurance that the 

stock size is at least as large as the 

estimate (NMFS, 2023). The abundance 

trend for this stock is unclear; therefore, 

there is no basis for adjusting these 

estimates (Young et al., 2023). 

Assuming the population has been 

stable, the maximum annual 4 takes of 

this stock proposed for authorization 

represents small numbers of this stock 

(0.18 percent of the stock assuming a 

NMIN of 2,241 individuals and 0.52 

percent of the stock assuming an NMIN

of 766 individuals). 

Based on the analysis contained 

herein of the proposed activity 

(including the proposed mitigation and 

monitoring measures) and the estimated 

take of marine mammals, NMFS 

preliminarily finds that small numbers 

of marine mammals would be taken 

relative to the population size of the 

affected species or stocks. 

Unmitigable Adverse Impact Analysis 

and Determination 

In order to promulgate regulations, 

NMFS must find that the takings 

authorized will not have an 

‘‘unmitigable adverse impact’’ on the 

subsistence uses of the affected marine 

mammal species or stocks by Alaskan 

Natives. NMFS has defined 

‘‘unmitigable adverse impact’’ in 50 CFR 

216.103 as an impact resulting from the 

specified activity: (1) That is likely to 

reduce the availability of the species to 

a level insufficient for a harvest to meet 

subsistence needs by: (i) Causing the 

marine mammals to abandon or avoid 

hunting areas; (ii) Directly displacing 

subsistence users; or (iii) Placing 

physical barriers between the marine 

mammals and the subsistence hunters; 

and (2) That cannot be sufficiently 

mitigated by other measures to increase 

the availability of marine mammals to 

allow subsistence needs to be met. 

While no significant subsistence 

activity currently occurs within or near 

the POA, Alaska Natives have 

traditionally harvested subsistence 

resources, including marine mammals, 

in upper Cook Inlet for millennia. 

CIBWs are more than a food source; they 

are important to the cultural and 

spiritual practices of Cook Inlet Native 

communities (NMFS, 2008b). Dena’ina 

Athabascans, currently living in the 

communities of Eklutna, Knik, Tyonek, 

and elsewhere, occupied settlements in 

Cook Inlet for the last 1,500 years and 

have been the primary traditional users 

of this area into the present. 

NMFS estimated that 65 CIBWs per 

year (range 21–123) were killed between 

1994 and 1998, including those 

successfully harvested and those struck 

and lost. NMFS concluded that this 

number was high enough to account for 

the estimated 14 percent annual decline 

in population during this time (Hobbs et 

al., 2008); however, given the difficulty 

of estimating the number of whales 

struck and lost during the hunts, actual 

mortality may have been higher. During 

this same period, population abundance 

surveys indicated a population decline 

of 47 percent, although the reason for 

this decline should not be associated 

solely with subsistence hunting and 

likely began well before 1994 (Rugh et 

al., 2000). 

In 1999, a moratorium was enacted 

(Pub. L. 106–31) prohibiting the 

subsistence harvest of CIBWs except 

through a cooperative agreement 

between NMFS and the affected Alaska 

Native organizations. NMFS began 

working cooperatively with the Cook 

Inlet Marine Mammal Council (CIMMC), 

a group of tribes that traditionally 

hunted CIBWs, to establish sustainable 

harvests. CIMMC voluntarily curtailed 

its harvests in 1999. In 2000, NMFS 

designated the Cook Inlet stock of 

beluga whales as depleted under the 

MMPA (65 FR 34590, May 31, 2000). 

NMFS and CIMMC signed CoManagement of the Cook Inlet Stock of 

Beluga Whales agreements in 2000, 

2001, 2002, 2003, 2005, and 2006. CIBW 

harvests between 1999 and 2006 

resulted in the strike and harvest of five 

whales, including one whale each in 

2001, 2002, and 2003, and two whales 

in 2005 (NMFS, 2008b). No hunt 

occurred in 2004 due to higher-thannormal mortality of CIBWs in 2003, and 

the Native Village of Tyonek agreed to 

not hunt in 2007. Since 2008, NMFS has 

examined how many CIBWs could be 

harvested during 5-year intervals based 

on estimates of population size and 

growth rate and determined that no 

harvests would occur between 2008 and 

2012 and between 2013 and 2017 

(NMFS, 2008b). The CIMMC was 

disbanded by unanimous vote of the 

CIMMC member Tribes’ representatives 

in June 2012, and a replacement group 

of Tribal members has not been formed 

to date. There has been no subsistence 

harvest of CIBWs since 2005 (NMFS, 

2022d). 

Subsistence harvest of other marine 

mammals in upper Cook Inlet is limited 

to harbor seals. Steller sea lions are rare 

in upper Cook Inlet; therefore, 

subsistence use of this species is not 

common. However, Steller sea lions are 

taken for subsistence use in lower Cook 

Inlet. Residents of the Native Village of 

Tyonek are the primary subsistence 

users in the upper Cook Inlet area. 

While harbor seals are hunted for 

subsistence purposes, harvests of this 

species for traditional and subsistence 

uses by Native peoples have been low 

in upper Cook Inlet (e.g., 33 harbor seals 

were harvested in Tyonek between 1983 

and 2013; see table 8–1 in the POA’s 

application), although these data are not 

currently being collected and 

summarized. As the POA’s proposed 

project activities will take place within 

the immediate vicinity of the POA, no 

activities will occur in or near Tyonek’s 

identified traditional subsistence 

hunting areas. As the harvest of marine 

mammals in upper Cook Inlet is 

historically a small portion of the total 

subsistence harvest and the number of 

marine mammals using upper Cook 

Inlet is proportionately small, the 

number of marine mammals harvested 

in upper Cook Inlet is expected to 

remain low. 

The potential impacts from 

harassment on stocks that are harvested 

in Cook Inlet would be limited to minor 


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behavioral changes (e.g., increased swim 

speeds, changes in dive time, temporary 

avoidance near the POA) within the 

vicinity of the POA. Some PTS may 

occur; however, the shift is likely to be 

slight due to the implementation of 

mitigation measures (e.g., shutdown 

zones, pre-clearance monitoring, bubble 

curtains, soft starts) and the shift would 

be limited to lower pile driving 

frequencies which are on the lower end 

of phocid and otariid hearing ranges. In 

summary, any impacts to harbor seals 

would be limited to those seals within 

Knik Arm (outside of any hunting area) 

and the very few takes of Steller sea 

lions in Knik Arm would be far removed 

in time and space from any hunting in 

lower Cook Inlet. 

The POA will communicate with 

representative Alaska Native 

subsistence users and Tribal members to 

identify and explain the measures that 

have been taken or will be taken to 

minimize any adverse effects of CTR on 

the availability of marine mammals for 

subsistence uses. In addition, the POA 

will adhere to the following 

communication procedures regarding 

marine mammal subsistence use within 

the Project area: 

(1) Send letters to the Kenaitze, 

Tyonek, Knik, Eklutna, Ninilchik, 

Salamatof, and Chickaloon Tribes 

informing them of the proposed project 

(i.e., timing, location, and features). 

Include a map of the proposed project 

area; identify potential impacts to 

marine mammals and mitigation efforts, 

if needed, to avoid or minimize impacts; 

and inquire about possible marine 

mammal subsistence concerns they 

have. 

(2) Follow up with a phone call to the 

environmental departments of the seven 

Tribal entities to ensure that they 

received the letter, understand the 

proposed project, and have a chance to 

ask questions. Inquire about any 

concerns they might have about 

potential impacts to subsistence hunting 

of marine mammals. 

(3) Document all communication 

between the POA and Tribes. 

(4) If any Tribes express concerns 

regarding proposed project impacts to 

subsistence hunting of marine 

mammals, propose a Plan of 

Cooperation between the POA and the 

concerned Tribe(s). 

The proposed project features and 

activities, in combination with a 

number of actions to be taken by the 

POA during project implementation, 

should avoid or mitigate any potential 

adverse effects on the availability of 

marine mammals for subsistence uses. 

Furthermore, although construction will 

occur within the traditional area for 

hunting marine mammals, the proposed 

project area is not currently used for 

subsistence activities. In-water pile 

installation and removal will follow 

mitigation procedures to minimize 

effects on the behavior of marine 

mammals and impacts will be 

temporary. 

For the NES1 project, the POA 

expressed that, if desired, regional 

subsistence representatives may support 

project marine mammal biologists 

during the monitoring program by 

assisting with collection of marine 

mammal observations and may request 

copies of marine mammal monitoring 

reports. The POA proposes the same 

option for the CTR project. 

Based on the description of the 

specified activity, the measures 

described to minimize adverse effects 

on the availability of marine mammals 

for subsistence purposes, and the 

proposed mitigation and monitoring 

measures, NMFS has preliminarily 

determined that there will not be an 

unmitigable adverse impact on 

subsistence uses from the POA’s 

proposed activities. 

Endangered Species Act 

Section 7(a)(2) of the Endangered 

Species Act of 1973 (ESA; 16 U.S.C. 

1531 et seq.) requires that each Federal 

agency insure that any action it 

authorizes, funds, or carries out is not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or result in the 

destruction or adverse modification of 

designated critical habitat. To ensure 

ESA compliance for the promulgation of 

regulations, NMFS consults internally 

whenever we propose to authorize take 

for endangered or threatened species, in 

this case with the NMFS Alaska 

Regional Office. 

NMFS Office of Protected Resources 

(OPR) is proposing to authorize take of 

Mexico-North Pacific humpback whales 

(including individuals from the Mexico 

DPS), CIBWs, and western DPS Steller 

sea lions, which are listed under the 

ESA. NMFS OPR has requested 

initiation of section 7 consultation on 

the promulgation of regulations and 

issuance of a subsequent LOA. NMFS 

will conclude the ESA consultation 

prior to reaching a determination 

regarding the proposed issuance of the 

authorization. 

Proposed Promulgation 

As a result of these preliminary 

determinations, NMFS proposes to 

promulgate regulations that allow for 

the authorization of take, by Level A 

harassment and Level B harassment, 

incidental to construction activities 

associated with the Cargo Terminals 

Replacement Project at the Don Young 

Port of Alaska in Anchorage, Alaska for 

a 5-year period from March 1, 2026, 

through February 28, 2031, provided the 

previously mentioned mitigation, 

monitoring, and reporting requirements 

are incorporated. 

Request for Information 

NMFS requests interested persons to 

submit comments, information, and 

suggestions concerning the POA’s 

request and the proposed regulations 

(see ADDRESSES). All comments will be 

reviewed and evaluated as we prepare a 

final rule and make final determinations 

on whether to issue the requested 

authorization. This proposed rule and 

referenced documents provide all 

environmental information relating to 

our proposed action for public review. 

Classification 

The Office of Management and Budget 

has determined that this proposed rule 

is not significant for purposes of 

Executive Order 12866. 

Pursuant to section 605(b) of the 

Regulatory Flexibility Act (RFA) (5 

U.S.C. 601 et seq.), the Chief Counsel for 

Regulation of the Department of 

Commerce has certified to the Chief 

Counsel for Advocacy of the Small 

Business Administration that this 

proposed rule, if adopted, would not 

have a significant economic impact on 

a substantial number of small entities. 

The POA is an enterprise activity of the 

Municipality of Anchorage, Alaska, 

meaning that it is a department of the 

Municipality which generates adequate 

revenue to support its operational costs 

and annual payments to the 

Municipality. The POA is the sole entity 

that would be subject to the 

requirements in these proposed 

regulations, and the POA is not a small 

governmental jurisdiction, small 

organization, or small business, as 

defined by the RFA, because it is a 

department of the local government. 

Because of this certification, a 

regulatory flexibility analysis is not 

required and none has been prepared. 

This proposed rule contains a 

collection-of-information requirement 

subject to the provisions of the 

Paperwork Reduction Act (PRA). 

Notwithstanding any other provision of 

law, no person is required to respond to 

nor shall a person be subject to a 

penalty for failure to comply with a 

collection of information subject to the 

requirements of the PRA unless that 

collection of information displays a 

currently valid OMB control number. 

These requirements have been approved 

by OMB under control number 0648– 


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0151 and include applications for 

regulations, subsequent LOAs, and 

reports. 

List of Subjects in 50 CFR Part 217 

Acoustics, Administrative practice 

and procedure, Construction, 

Endangered and threatened species, 

Marine mammals, Mitigation and 

monitoring requirements, Reporting 

requirements, Wildlife. 

Dated: October 18, 2024. 

Samuel D. Rauch III, 

Deputy Assistant Administrator for 

Regulatory Programs, National Marine 

Fisheries Service. 

For reasons set forth in the preamble, 

NMFS proposes to amend 50 CFR part 

217 to read as follows: 

PART 217—REGULATIONS 

GOVERNING THE TAKING AND 

IMPORTING OF MARINE MAMMALS 

■ 1. The authority citation for part 217 

continues to read as follows: 

Authority: 16 U.S.C. 1361 et seq. 

■ 2. Add subpart B, consisting of 

§§ 217.11 through 217.19, to read as 

follows: 

Subpart B—Taking Marine Mammals 

Incidental to the Port of Alaska 

Modernization Program Phase 2B: Cargo 

Terminals Replacement Project in 

Anchorage, Alaska 

Sec. 

217.11 Specified activity and specified 

geographical region. 

217.12 Effective dates. 

217.13 Permissible methods of taking. 

217.14 Prohibitions. 

217.15 Mitigation requirements. 

217.16 Requirements for monitoring and 

reporting. 

217.17 Letters of Authorization. 

217.18 Modifications of Letters of 

Authorization. 

217.19 [Reserved] 

Subpart B—Taking Marine Mammals 

Incidental to the Port of Alaska 

Modernization Program Phase 2B: 

Cargo Terminals Replacement Project 

in Anchorage, Alaska 

§ 217.11 Specified activity and specified 

geographical region. 

(a) The incidental taking of marine 

mammals by the Port of Alaska (POA) 

may be authorized in a Letter of 

Authorization (LOA) only if it occurs at 

or around the Port of Alaska, including 

waters of Knik Arm and Upper Cook 

Inlet near Anchorage, Alaska incidental 

to the specified activities outlined in 

paragraph (b) of this section. 

(b) The specified activities are 

construction and demolition activities 

associated with the Cargo Terminals 

Replacement Project under the Port of 

Alaska Modernization Program at the 

Don Young Port of Alaska in Anchorage, 

Alaska. 

§ 217.12 Effective dates. 

Regulations in this subpart are 

effective from March 1, 2026, until 

February 28, 2031. 

§ 217.13 Permissible methods of taking. 

Under a LOA issued pursuant to 

§ 216.106 of this chapter and § 217.17, 

the POA and those persons it authorizes 

or funds to conduct activities on its 

behalf may incidentally, but not 

intentionally, take marine mammals 

within the specified geographical region 

by harassment associated with the 

specified activities provided they are in 

compliance with all terms, conditions, 

and requirements of the regulations in 

this subpart and the applicable LOA. 

§ 217.14 Prohibitions. 

(a) Except for the takings permitted in 

§ 217.13 and authorized by a LOA 

issued under § 216.106 of this chapter 

and § 217.17, it is unlawful for any 

person to do any of the following in 

connection with the specified activities: 

(1) Violate or fail to comply with the 

terms, conditions, and requirements of 

this subpart or a LOA issued under this 

subpart; 

(2) Take any marine mammal not 

specified in such LOA; 

(3) Take any marine mammal 

specified in such LOA in any manner 

other than specified; 

(4) Take a marine mammal specified 

in such LOA if NMFS determines such 

taking results in more than a negligible 

impact on the species or stocks of such 

marine mammal; or 

(5) Take a marine mammal specified 

in such LOA after NMFS determines 

such taking results in an unmitigable 

adverse impact on the species or stock 

of such marine mammal for taking for 

subsistence uses. 

(b) [Reserved] 

§ 217.15 Mitigation requirements. 

(a) When conducting the specified 

activities identified in § 217.11(b), POA 

must implement the mitigation 

measures contained in this section and 

any LOA issued under §§ 216.106 of this 

chapter and 217.17. These mitigation 

measures include, but are not limited to: 

(1) A copy of any issued LOA must be 

in the possession of the POA, its 

designees, and work crew personnel 

operating under the authority of the 

issued LOA. 

(2) The POA must ensure that 

construction supervisors and crews, the 

monitoring team and relevant POA staff 

are trained prior to the start of all pile 

driving so that responsibilities, 

communication procedures, monitoring 

protocols, and operational procedures 

are clearly understood. New personnel 

joining during the project must be 

trained prior to commencing work. 

(3) The POA must employ Protected 

Species Observers (PSOs) and establish 

monitoring locations pursuant to 

§ 217.16 and as described in a NMFSapproved Marine Mammal Monitoring 

and Mitigation Plan. 

(i) For all pile driving activities, landbased PSOs must be stationed at the best 

vantage points practicable to monitor for 

marine mammals and implement 

shutdown/delay procedures. A 

minimum of 4 locations must be used to 

monitor the designated harassment 

zones to the maximum extent possible 

based on daily visibility conditions. 

Additional PSOs must be added if 

warranted by site conditions and/or the 

level of marine mammal activity in the 

area. PSOs must be able implement 

shutdown or delay procedures when 

applicable through communication with 

the equipment operator. 

(ii) If during pile driving activities, 

PSOs can no longer effectively monitor 

the entirety of the Cook Inlet beluga 

whale (CIBW) shutdown zone due to 

environmental conditions (e.g., fog, rain, 

wind), pile driving may continue only 

until the current segment of the pile is 

driven; no additional sections of pile or 

additional piles may be driven until 

conditions improve such that the 

shutdown zone can be effectively 

monitored. If the shutdown zone cannot 

be monitored for more than 15 minutes, 

the entire zone must be cleared again for 

30 minutes prior to reinitiating pile 

driving. 

(4) Pre-start Clearance Monitoring 

must take place from 30 minutes prior 

to initiation of pile driving activity (i.e., 

pre-start clearance monitoring) through 

30 minutes post-completion of pile 

driving activity. 

(i) Pre-start clearance monitoring must 

be conducted during periods of 

visibility sufficient for the Lead PSO to 

determine that the shutdown zones are 

clear of marine mammals. 

(ii) Pile driving may commence if, 

following 30 minutes of observation, it 

is determined by the Lead PSO that the 

shutdown zones are clear of marine 

mammals and for CIBW, any observed 

whale(s) is at least 100 meters past the 

shutdown zone and on a path away 

from the zone or the whale has not been 

re-sighted for 30 minutes. 

(5) For all pile driving activity, the 

POA must implement shutdown zones 

with radial distances as identified in a 


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LOA issued under § 216.106 of this 

chapter and § 217.17. 

(i) If a marine mammal is observed 

entering or within the shutdown zone, 

all pile driving activities, including soft 

starts, at that location must be halted. If 

pile driving is halted or delayed due to 

the presence of a marine mammal, the 

activity may not commence or resume 

until either the animal has voluntarily 

left and is been visually confirmed 

beyond the shutdown zone or 15 

minutes (non-CIBWs) or 30 minutes 

(CIBWs) have passed without redetection of the animal. Specific to 

CIBW, if a CIBW(s) is observed within 

or on a path towards the shutdown 

zone, pile driving activities, including 

soft starts, must shut down and not recommence until the whale has traveled 

at least 100 m beyond the shutdown 

zone and is on a path away from such 

zone or until no CIBW has been 

observed in the shutdown zone for 30 

minutes. 

(ii) In the event of a delay or 

shutdown of activity resulting from 

marine mammals in the shutdown zone, 

animal behavior must be monitored and 

documented. 

(iii) If work ceases for more than 30 

minutes, the shutdown zones must be 

cleared again for 30 minutes prior to 

reinitiating pile driving. A 

determination that the shutdown zone is 

clear must be made during a period of 

good visibility. 

(iv) If a shutdown procedure should 

be initiated but human safety is at risk, 

as determined by the best professional 

judgment of the vessel operator or 

project engineer, the in-water activity, 

including pile driving, is allowed to 

continue until the risk to human safety 

has dissipated. In this scenario, pile 

driving may continue only until the 

current segment of the pile is driven; no 

additional sections of pile or additional 

piles may be driven until the Lead PSO 

has determined that the shutdown zones 

are clear of marine mammals and for 

Cook Inlet beluga whales (CIBW), any 

observed whale(s) is at least 100 meters 

past the shutdown zone and on a path 

away from the zone. 

(v) For in-water construction activities 

other than pile driving (e.g., barge 

positioning; use of barge-mounted 

excavators; dredging), if a marine 

mammal comes within 10 m, POA must 

cease operations and reduce vessel 

speed to the minimum level required to 

maintain steerage and safe working 

conditions. If human safety is at risk, as 

determined by the best professional 

judgment of the vessel operator or 

project engineer, the in-water activity is 

allowed to continue until the risk to 

human safety has dissipated. 

(6) The POA must use soft start 

techniques when impact pile driving. 

Soft start requires contractors to conduct 

three sets of strikes (three strikes per set) 

at reduced hammer energy with a 30- 

second waiting period between each set. 

A soft start must be implemented at the 

start of each day’s impact pile driving 

and at any time following cessation of 

impact pile driving for a period of 30 

minutes or longer. 

(7) The POA must use bubble curtains 

for all temporary (36- or 24-in diameter) 

piles during both vibratory and impact 

pile driving in water depths greater than 

3 meters (9.8 ft) between August 1 and 

October 31. Bubble curtains must be 

used for all permanent piles (72-in 

diameter) during both vibratory and 

impact pile driving in waters deeper 

than 3 meters (9.8 feet). The bubble 

curtain must be operated to achieve 

optimal performance. At a minimum, 

the bubble curtain must: 

(i) The bubble curtain must distribute 

air bubbles around 100 percent of the 

piling perimeter for the full depth of the 

water column. 

(ii) The lowest bubble ring must be in 

contact with the mudline and/or rock 

bottom for the full circumference of the 

ring, and the weights attached to the 

bottom ring shall ensure 100 percent 

mudline and/or rock bottom contact. No 

parts of the ring or other objects shall 

prevent full mudline and/or rock bottom 

contact. 

(iii) Air flow to the bubblers must be 

balanced around the circumference of 

the pile. 

(8) Pile driving activity must be halted 

upon observation of a species entering 

or within the harassment zone for either 

a species for which incidental take is 

not authorized or a species for which 

incidental take has been authorized but 

the authorized number of takes has been 

met. 

(b) [Reserved] 

§ 217.16 Requirements for monitoring and 

reporting. 

(a) The POA must submit a Marine 

Mammal Monitoring and Mitigation 

Plan to NMFS for approval at least 90 

days before the start of construction and 

abide by the Plan, if approved. 

(b) Monitoring must be conducted by 

qualified, NMFS-approved PSOs, in 

accordance with the following 

conditions: 

(1) PSOs must be independent of the 

activity contractor (e.g., employed by a 

subcontractor) and have no other 

assigned tasks during monitoring duties. 

(2) PSOs must be approved by NMFS 

prior to beginning work on the specified 

activities. 

(3) PSOs must be trained in marine 

mammal identification and behavior. 

(i) A designated Project Lead PSO 

must always be on site. The Project Lead 

PSO must have prior experience 

performing the duties of a PSO during 

in-water construction activities 

pursuant to a NMFS-issued ITA or 

Letter of Concurrence. 

(ii) Each PSO station must also have 

a designated Station Lead PSO specific 

to that station and shift. These Station 

Lead PSOs must have prior experience 

working as a PSO during in-water 

construction activities; 

(iii) Other PSOs may substitute other 

relevant experience (including relevant 

Alaska Native traditional knowledge), 

education (degree in biological science 

or related field), or training for prior 

experience performing the duties of a 

PSO during construction activity 

pursuant to a NMFS-issued incidental 

take authorization. 

(4) PSO stations must be elevated 

platforms constructed on top of 

shipping containers or a similar base 

that is at least 8′6′′ high (i.e., the 

standard height of a shipping container) 

that can support at least three PSOs and 

their equipment. The platforms must be 

stable enough to support use of a 

theodolite and must be located to 

optimize the PSO’s ability to observe 

marine mammals and the shutdown 

zones. Each PSO station must have at 

least two PSOs on watch at any given 

time, including the Station Lead PSO. 

(5) If the POA is conducting in-water 

work for other projects that includes 

PSOs, the PSOs for the Cargo Terminals 

Replacement Project must be in realtime contact with those PSOs, and both 

sets of PSOs must share all information 

regarding marine mammal sightings 

with each other. 

(c) The POA must submit weekly 

monitoring reports within 14 days after 

the conclusion of each calendar week 

during each Cargo Terminals 

Replacement Project construction 

season. These reports must include a 

summary of marine mammal species 

and behavioral observations, 

construction shutdowns or delays, and 

construction work completed during the 

reporting period. The weekly reports 

also must include an assessment of the 

amount of construction remaining to be 

completed (i.e., the number of estimated 

hours of work remaining), in addition to 

the number of beluga whales observed 

within estimated harassment zones to 

date. 

(d) The POA must submit a draft 

annual summary monitoring report on 

all monitoring conducted during each 

construction season which includes 

final electronic data sheets within 90 


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calendar days after the completion of 

each construction season or 60 days 

prior to a requested date of issuance of 

any future incidental take authorization 

for projects at the same location, 

whichever comes first. A draft 

comprehensive 5-year summary report 

must also be submitted to NMFS within 

90 days of the end of year 5 of the 

project. The reports must detail the 

monitoring protocol and summarize the 

data recorded during monitoring. If no 

comments are received from NMFS 

within 30 days of receipt of the draft 

report, the report may be considered 

final. If comments are received, a final 

report addressing NMFS comments 

must be submitted within 30 days after 

receipt of comments. At a minimum, the 

reports must contain: 

(1) Dates and times (begin and end) of 

all marine mammal monitoring; 

(2) Construction activities occurring 

during each daily observation period, 

including how many and what type of 

piles were driven or removed, by what 

method (i.e., impact or vibratory), the 

total duration of driving time for each 

pile (vibratory driving), and number of 

strikes for each pile (impact driving); 

(3) Environmental conditions during 

monitoring periods (at beginning and 

end of PSO shift and whenever 

conditions change significantly), 

Beaufort sea state, and any other 

relevant weather conditions including 

cloud cover, fog, sun glare, and overall 

visibility to the horizon, and estimated 

observable distance (if less than the 

harassment zone distance); 

(4) Upon observation of a marine 

mammal, the following information 

should be collected: 

(i) Name of the PSO who sighted the 

animal, observer location, and activity 

at time of sighting: 

(ii) Time of sighting; 

(iii) Identification of the animal (e.g., 

genus/species, lowest possible 

taxonomic level, or unidentified), PSO 

confidence in identification, and the 

composition of the group if there is a 

mix of species; 

(iv) Distances and bearings of each 

marine mammal observed in relation to 

the pile being driven for each sighting 

(if pile driving was occurring at time of 

sighting); 

(v) Estimated number of animals 

(min/max/best); 

(vi) Estimated number of animals by 

cohort (adults, juveniles, neonates, 

group composition, etc.); 

(vii) Animal’s closest point of 

approach and estimated time spent 

within the harassment zone; 

(viii) Description of any marine 

mammal behavioral observations (e.g., 

observed behaviors such as feeding or 

traveling), including an assessment of 

behavioral responses to the activity (e.g., 

no response or changes in behavioral 

state such as ceasing feeding, changing 

direction, flushing, or breaching); 

(ix) Detailed information about any 

implementation of any mitigation (e.g., 

shutdowns and delays), a description of 

specific actions that ensued, and 

resulting changes in the behavior of the 

animal, if any; and 

(x) All PSO datasheets and raw 

sightings data in electronic spreadsheet 

format. 

(e) In the event that personnel 

involved in the construction activities 

discover an injured or dead marine 

mammal, the POA must report the 

incident to NMFS Office of Protected 

Resources (OPR) and to the Alaska 

Regional Stranding Coordinator no later 

than 24 hours after the initial 

observation. If the death or injury was 

caused by the specified activity, the 

POA must immediately cease the 

specified activities until NMFS OPR is 

able to review the circumstances of the 

incident. The POA must not resume 

their activities until notified by NMFS. 

The report must include the following 

information: 

(1) Time, date, and location (latitude/ 

longitude) of the first discovery (and 

updated location information if known 

and applicable); 

(2) Species identification (if known) 

or description of the animal(s) involved; 

(3) Condition of the animal(s) 

(including carcass condition if the 

animal is dead); 

(4) Observed behaviors of the 

animal(s), if alive; 

(5) If available, photographs or video 

footage of the animal(s); and 

(6) General circumstances under 

which the animal was discovered. 

§ 217.17 Letters of Authorization. 

(a) To incidentally take marine 

mammals pursuant to these regulations, 

the POA must apply for and obtain an 

LOA. 

(b) An LOA, unless suspended or 

revoked, may be effective for a period of 

time not to exceed the effective dates of 

this subpart. 

(c) If an LOA expires prior to the end 

of the effective dates of this subpart, the 

POA may apply for and obtain a 

renewal of the LOA. 

(d) In the event of projected changes 

to the activity or to mitigation and 

monitoring measures required by an 

LOA, the POA must apply for and 

obtain a modification of the LOA as 

described in § 217.18. 

(e) The LOA must set forth the 

following information: 

(1) Permissible methods of incidental 

taking; 

(2) Means of effecting the least 

practicable adverse impact (i.e., 

mitigation) on the species, its habitat, 

and on the availability of the species for 

subsistence uses; and 

(3) Requirements for monitoring and 

reporting. 

(f) Issuance of the LOA must be based 

on a determination that the level of 

taking will be consistent with the 

findings made for the total taking 

allowable under this subpart. 

(g) Notice of issuance or denial of an 

LOA must be published in the Federal 

Register within 30 days of a 

determination. 

§ 217.18 Modifications of Letters of 

Authorization. 

(a) A LOA issued under §§ 216.106 of 

this chapter and 217.17 for the specified 

activities may be modified upon request 

by the POA, provided that: 

(1) The specified activity and 

mitigation, monitoring, and reporting 

measures, as well as the anticipated 

impacts, are the same as those described 

and analyzed for this subpart; and 

(2) NMFS determines that the 

mitigation, monitoring, and reporting 

measures required by the previous LOA 

were implemented. 

(b) For LOA modification by the POA 

that includes changes to the specified 

activity or the mitigation, monitoring, or 

reporting measures that do not change 

the findings made for the regulations in 

this subpart or result in no more than a 

minor change in the total estimated 

number of takes (or distribution by 

species or years), NMFS may publish a 

notice of proposed LOA in the Federal 

Register, including the associated 

analysis of the change and solicit public 

comment before issuing the LOA. 

(c) A LOA issued under § 216.106 of 

this chapter and § 217.17 for the 

specified activity may be modified by 

NMFS under the following 

circumstances: 

(1) NMFS may modify the existing 

mitigation, monitoring, or reporting 

measures, after consulting with the POA 

regarding the practicability of the 

modifications, if doing so creates a 

reasonable likelihood of more 

effectively accomplishing the goals of 

the mitigation and monitoring measures; 

(i) Possible sources of data that could 

contribute to the decision to modify the 

mitigation, monitoring, or reporting 

measures in an LOA include, but are not 

limited to: 

(A) Results from the POA’s 

monitoring; 

(B) Results from other marine 

mammal and/or sound research or 

studies; and 

(C) Any information that reveals 

marine mammals may have been taken 


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in a manner, extent or number not 

authorized by this subpart or 

subsequent LOAs; and 

(ii) If, through adaptive management, 

the modifications to the mitigation, 

monitoring, or reporting measures are 

substantial, NMFS shall publish a notice 

of proposed LOA in the Federal 

Register and solicit public comment; 

(2) If NMFS determines that an 

emergency exists that poses a significant 

risk to the well-being of the species or 

stocks of marine mammals specified in 

a LOA issued pursuant to § 216.106 of 

this chapter and § 217.17, a LOA may be 

modified without prior notice or 

opportunity for public comment. 

Notification will be published in the 

Federal Register within 30 days of the 

action. 

§ 217.19 [Reserved] 

[FR Doc. 2024–24580 Filed 10–25–24; 8:45 am] 

BILLING CODE 3510–22–P 


lotter on DSK11XQN23PROD with PROPOSALS3