[Federal Register Volume 87, Number 53 (Friday, March 18, 2022)]
[Notices]
[Pages 15387-15408]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-05561]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XB799]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Ferry Berth Improvements in Tongass 
Narrows in Ketchikan, Alaska

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

ACTION: Notice; issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
the Alaska Department of Transportation and Public Facilities (ADOT) to 
incidentally harass, by Level A harassment and Level B harassment only, 
marine mammals during construction activities associated with 
construction of four ferry berth facilities in Tongass Narrows in 
Ketchikan, Alaska.

DATES: This authorization is effective from March 5, 2022 through March 
4, 2023.

FOR FURTHER INFORMATION CONTACT: Leah Davis, Office of Protected 
Resources, NMFS, (301) 427-8401. 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/permit/incidental-take-authorizations-under-
marine-mammal-protection-act. In case of problems accessing these 
documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    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). Further, 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

[[Page 15388]]

``mitigation''); and requirements pertaining to the mitigation, 
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.

Summary of Request

    On August 19, 2021, NMFS received a request from the ADOT for an 
IHA to take marine mammals incidental to the construction of two ferry 
berth facilities in Tongass Narrows in Ketchikan, Alaska: The Gravina 
Airport Ferry Layup Facility and the Gravina Freight Facility. On 
December 17, 2021 we received a revised request that included 
additional work components associated with the Revilla New Ferry Berth 
and Upland Improvements and the New Gravina Island Shuttle Ferry Berth 
and Related Terminal Improvements in the same region. The application 
was deemed adequate and complete on January 4, 2022. ADOT's request is 
for take of a small number of eight species of marine mammals, by Level 
B harassment and Level A harassment. Of those eight species, five 
(Steller sea lion (Eumetopias jubatus), harbor seal (Phoca vitulina 
richardii), harbor porpoise (Phocoena phocoena), Dall's porpoise 
(Phocoenoides dalli) and minke whale (Balaenoptera acutorostrata)) may 
also be taken by Level A harassment. Neither ADOT nor NMFS expects 
serious injury or mortality to result from this activity and, 
therefore, an IHA is appropriate.
    NMFS previously issued two consecutive IHAs and a Renewal IHA to 
ADOT for this work (85 FR 673, January 7, 2020; 86 FR 23938, May 05, 
2021). ADOT 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 Description of 
Marine Mammals in the Area of Specified Activities and Marine Mammal 
Occurrence and Take Calculation and Estimation sections. An IHA for the 
first phase of construction of the Ketchikan-Gravina Access Project was 
issued to ADOT on December 20, 2019 (85 FR 673, January 7, 2020). 
Complete construction of two of those components, the Revilla New Ferry 
Berth and Upland Improvements and Gravina Island Shuttle Ferry Berth 
Facility/Related Terminal Improvements, did not occur within the 
timeframe authorized by the Phase 1 IHA and will not be finished before 
the expiration of the subsequent one-year renewal (86 FR 23938, May 05, 
2021). Therefore, ADOT requested a new IHA for incidental take 
associated with the continued marine construction of these facilities.

Description of the Specified Activity

    ADOT is making improvements to existing ferry berths and 
constructing new ferry berths on Gravina Island and Revillagigedo 
(Revilla) Island in Tongass Narrows, near Ketchikan in southeast Alaska 
(Figure 1 of proposed IHA; 87 FR 5980; February 2, 2022). These ferry 
facilities provide the only public access between the city of 
Ketchikan, AK on Revilla Island, and the Ketchikan International 
Airport on Gravina Island. The project's planned activities that have 
the potential to take marine mammals, by Level A harassment and Level B 
harassment, include vibratory and impact pile driving, down-the-hole 
(DTH) operations for pile installation (rock socketing of piles and 
tension anchors to secure piles), and vibratory pile removal. The 
marine construction associated with the activities is planned to occur 
over 91 non-consecutive days over one year beginning March 2022.
    A detailed description of the planned construction project is 
provided in the Federal Register notice for the proposed IHA (87 FR 
5980; February 2, 2022). Since that time, no changes have been made to 
the planned activities. Therefore, a detailed description is not 
provided here. Please refer to that Federal Register notice for the 
description of the specific activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to ADOT was published in 
the Federal Register on February 2, 2022 (87 FR 5980). That notice 
described, in detail, ADOT's activity, the marine mammal species that 
may be affected by the activity, and the anticipated effects on marine 
mammals. During the 30-day public comment period, NMFS did not receive 
any public comments.

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
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 1 lists all species or stocks for which take is expected and 
proposed to be authorized for this specified activity, 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. For taxonomy, we follow 
Committee on Taxonomy (2021). 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 (as described in NMFS' 
SARs). While no mortality is anticipated or authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species 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 SARs (e.g., Muto et al. 2021). All values presented 
in Table 1 are the most recent available at the time of publication and 
are available in the draft 2021 SARs (Muto et al. 2021; available 
online at: https://www.fisheries.noaa.gov/national/marine-mammal-
protection/draft-marine-mammal-stock-assessment-reports).

[[Page 15389]]



                                   Table 1--Marine Mammal Species or Stocks for Which Take is Expected and Authorized
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            Stock abundance Nbest,
                                                                                         ESA/MMPA status;   (CV; Nmin; most recent             Annual M/
             Common name                  Scientific name             MMPA stock          strategic (Y/N)    abundance survey) \2\     PBR       SI \3\
                                                                                                \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
    Humpback whale..................  Megaptera novaeangliae.  Central North Pacific..  E, D, Y             10,103 (0.3; 7,890;            83         26
                                                                                                             2006).
    Minke whale.....................  Balaenoptera             Alaska.................  -, N                N.A. (See SAR; N.A.;          UND          0
                                       acutorostrata.                                                        see SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                            Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer whale....................  Orcinus orca...........  Alaska Resident........  -, N                2,347 (N.A.; 2,347;            24          1
                                                                                                             2012).
                                                               West Coast Transient...  -, N                349 (N.A, 349; 2018)..        3.5       *0.4
                                                               Northern Resident......  -, N                302 (N.A.; 302; 2018..        2.2        0.2
    Pacific white-sided dolphin.....  Lagenorhynchus           North Pacific..........  -,-; N              26,880 (N.A.; N.A.;           UND          0
                                       obliquidens.                                                          1990).
Family Phocoenidae:
    Harbor porpoise.................  Phocoena phocoena......  Southeast Alaska.......  -, Y                See SAR (see SAR; see     See SAR         34
                                                                                                             SAR; 2012).
    Dall's porpoise.................  Phocoenoides dalli.....  Alaska.................  -, N                See SAR (see SAR; see     See SAR         37
                                                                                                             SAR; 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Steller sea lion................  Eumetopias jubatus.....  Eastern U.S............  -,-, N              43,201 (see SAR;            2,592        112
                                                                                                             43,201; 2017).
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina           Clarence Strait........  -, N                27,659 (See SAE;              746         40
                                       richardii.                                                            24,854; 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-
  assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury (M/SI) 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. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.

    All species that could potentially occur in the project area are 
included in Table 3-1 of ADOT's IHA application. However, the spatial 
occurrence of gray whale and fin whale is such that take is not 
expected to occur, and they are not discussed further beyond the 
explanation provided here. Gray whales have not been reported by any 
local experts or recorded in monitoring reports and it would be 
extremely unlikely for a gray whale to enter Tongass Narrows or the 
small portions of Revillagigedo Channel this project will impact. 
Similarly for fin whale, sightings have not been reported and it would 
be unlikely for a fin whale to enter the project area as they are 
generally associated with deeper, more offshore waters. The eight 
species (with 10 managed stocks) in Table 1 temporally and spatially 
co-occur with the activity to the degree that take is reasonably likely 
to occur, and we have authorized it.
    A detailed description of the of the species likely to be affected 
by ADOT's project, including brief introductions to the species and 
relevant stocks as well as available information regarding population 
trends and threats, and information regarding local occurrence, were 
provided in the Federal Register notice for the proposed IHA (87 FR 
5980; February 2, 2022); since that time, we are not aware of any 
changes in the status of these species and stocks; therefore, detailed 
descriptions are not provided here. Please refer to that Federal 
Register notice for these descriptions. Please also refer to NMFS' 
website (https://www.fisheries.noaa .gov/find-species) for generalized 
species accounts.

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. Current data indicate that 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) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) 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 low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 2.

[[Page 15390]]



                  Table 2--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans           150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true    275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)     50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* 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).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al. 2006; Kastelein et al. 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Eight marine mammal species (six cetacean and two pinniped (one otariid 
and one phocid) species) have the reasonable potential to co-occur with 
the planned activities. Please refer to Table 1. Of the cetacean 
species that may be present, two are classified as low-frequency 
cetaceans (i.e., all mysticete species), two are classified as mid-
frequency cetaceans (i.e., all delphinid and ziphiid species and the 
sperm whale), and two are classified as high-frequency cetaceans (i.e., 
harbor porpoise, Dall's porpoise and Kogia spp.).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from the ADOT's activities have the 
potential to result in take of marine mammals by Level B harassment and 
Level A harassment in the vicinity of the survey area. The notice of 
proposed IHA (87 FR 5980; February 2, 2022) included a discussion of 
the effects of anthropogenic noise on marine mammals and the potential 
effects of underwater noise from ADOT's construction activities on 
marine mammals and their habitat. That information and analysis is 
incorporated by reference into this final IHA and is not repeated here; 
please refer to the notice of the proposed IHA (87 FR 5980; February 2, 
2022).
    The Estimated Take section 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 section, and 
the Mitigation Measures section, to draw conclusions regarding the 
likely impacts of these activities on the reproductive success or 
survivorship of individuals and how those impacts on individuals are 
likely to impact marine mammal species or stocks. We also provided 
additional description of sound sources in our notice of proposed IHA 
(87 FR 5980; February 2, 2022).

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized through this IHA, which will inform both NMFS' consideration 
of ``small numbers'' and the negligible impact determination.
    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 will primarily be by Level B harassment, as use of 
the acoustic sources (i.e., impact and vibratory pile driving and DTH) 
have 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 mysticetes, high 
frequency species and phocids because predicted auditory injury zones 
are larger than for mid-frequency species and otariids. Auditory injury 
is unlikely to occur to mid-frequency species and otariids. The 
required mitigation and monitoring measures are expected to minimize 
the severity of such taking to the extent practicable.
    As described previously, no mortality is anticipated or authorized 
for this activity. Below we describe how the take is estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of 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 take estimate.

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 expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment for non-explosive sources--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 (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and

[[Page 15391]]

can be difficult to predict (Southall et al. 2007, Ellison et al. 
2012). Based on what the available science indicates and the practical 
need to use a threshold based on a factor that is both predictable and 
measurable for most activities, NMFS uses a generalized acoustic 
threshold based on received level to estimate the onset of behavioral 
harassment. NMFS predicts that marine mammals are likely to be 
behaviorally harassed in a manner we consider Level B harassment when 
exposed to underwater anthropogenic noise above received levels of 120 
dB re 1 microPascal ([mu]Pa) (root mean square (rms)) for continuous 
(e.g., vibratory pile-driving, DTH) and above 160 dB re 1 [mu]Pa (rms) 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources. This take estimation includes 
disruption of behavioral patterns resulting directly in response to 
noise exposure (e.g., avoidance), as well as that resulting indirectly 
from associated impacts such as TTS or masking. ADOT's planned activity 
includes the use of continuous (vibratory pile driving/removal and DTH) 
and impulsive (impact pile driving and DTH) sources, and therefore both 
the 120 and 160 dB re 1 [mu]Pa (rms) thresholds are applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies 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). ADOT's planned activity includes the use 
of impulsive (impact pile driving and DTH) and non-impulsive (vibratory 
pile driving/removal and DTH) sources.
    These thresholds are provided in Table 3 below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/
marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds * (received level)
             Hearing group             -------------------------------------------------------------------------
                                                Impulsive                          Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans..........  Cell 1: Lpk,flat: 219 dB;  Cell 2: LE,LF,24h: 199 dB.
                                         LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans..........  Cell 3: Lpk,flat: 230 dB;  Cell 4: LE,MF,24h: 198 dB.
                                         LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.........  Cell 5: Lpk,flat: 202 dB;  Cell 6: LE,HF,24h: 173 dB.
                                         LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)....  Cell 7: Lpk,flat: 218 dB;  Cell 8: LE,PW,24h: 201 dB.
                                         LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)...  Cell 9: Lpk,flat: 232 dB;  Cell 10: LE,OW,24h: 219 dB.
                                         LE,OW,24h: 203 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 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
  National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
  incorporating frequency weighting, which is not the intent for this 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 will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the project. Marine 
mammals are expected to be affected via sound generated by the primary 
components of the project (i.e., impact pile driving, vibratory pile 
driving, vibratory pile removal, and DTH).
    In order to calculate distances to the Level A harassment and Level 
B harassment sound thresholds for the methods and piles being used in 
this project, NMFS used acoustic monitoring data from other locations 
to develop source levels for the various pile types, sizes and methods 
(Table 4). Note that piles of differing sizes have different sound 
source levels (SSLs).
    Empirical data from recent ADOT sound source verification (SSV) 
studies at Ketchikan were used to estimate SSLs for vibratory and 
impact driving of 30-inch steel pipe piles (Denes et al. 2016). Data 
from Ketchikan was used because of its proximity to this project in 
Tongass Narrows. However, the use of data from Alaska sites was not 
appropriate in all instances. Details are described below.
    For vibratory driving of 24-inch steel piles, data from a Navy pile 
driving project in the Puget Sound, WA was reviewed (Navy 2015). From 
this review, ADOT determined the Navy's suggested source value of 161 
decibels (dB) root mean squared (rms) was an appropriate proxy source 
value, and NMFS concurs. Because the source value of smaller piles of 
the same general type (steel in this case) are not expected to exceed a 
larger pile, the same 161 dB rms source value was used for 20-inch 
steel piles. This assumption conforms with source values presented in 
Navy (2015) for a project using 16-inch steel piles at Naval Base 
Kitsap in Bangor, WA.
    ADOT used source values of 177 dB sound exposure level (SEL) and 
190 dB rms for impact driving of 24-inch and 20-inch steel piles. These 
values were determined based on summary values presented in Caltrans 
(2015) for impact driving of 24-inch steel piles. NMFS concurs that the 
same source value was an acceptable proxy for impact driving of 20-inch 
steel piles.
    Sound pressure levels in the water column resulting from DTH are 
not well studied. Because DTH hole creation includes both impulsive and 
continuous components, NMFS guidance currently recommends that it be 
treated as a continuous sound for Level B calculations and as an 
impulsive sound for Level A calculations (Table 10). In the absence of 
data specific to different hole sizes, current NMFS guidance

[[Page 15392]]

recommends that calculation of Level B zones for DTH use the same 
continuous SSL of 167 dB SEL for all hole sizes (Heyvaert and Reyff 
2021). Recommended SSLs for 30-inch and 24-inch holes as well as 8-inch 
holes for tension anchors and micropiles for use in the calculation of 
Level A harassment thresholds are provided by current NMFS guidance and 
in Table 4.

Table 4--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation, DTH,
                                           and Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
Method and pile type                                   SSL at 10 m                           Literature source
----------------------------------------------------------------------------------------------------------------
Vibratory hammer..............                           dB rms
----------------------------------------------------------------------------------------------------------------
30-inch steel piles...........                             162                            Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch steel piles...........                             161                            Navy 2015.
----------------------------------------------------------------------------------------------------------------
20-inch steel piles...........                             161                            Navy 2015.
----------------------------------------------------------------------------------------------------------------
DTH of rock sockets and                                  dB rms                           ......................
 tension anchors.
----------------------------------------------------------------------------------------------------------------
All pile diameters............                             167                            Heyvaert and Reyff
                                                                                           2021.
----------------------------------------------------------------------------------------------------------------
DTH of rock sockets and         dB SELss                     dB peak                      ......................
 tension anchors.
----------------------------------------------------------------------------------------------------------------
30-inch rock socket...........  164                          194                          Reyff and Heyvaert
                                                                                           2019; Reyff 2020;
                                                                                           Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch rock socket...........  159                          184                          Heyvaert and Reyff
                                                                                           2021.
----------------------------------------------------------------------------------------------------------------
8-inch tension anchor/          144                          170                          Reyff 2020.
 micropile.
----------------------------------------------------------------------------------------------------------------


 
 
----------------------------------------------------------------------------------------------------------------
Impact Hammer                   dB rms              dB SEL              dB peak
----------------------------------------------------------------------------------------------------------------
30-inch steel piles...........  195                 181                 209                Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch steel piles...........  190                 177                 203                Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
20-inch steel piles...........  190                 177                 202                Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
Note: It is assumed that noise levels during pile installation and removal are similar. SEL = sound exposure
  level; dB peak = peak sound level; rms = root mean square.

    Simultaneous use of two impact, vibratory, or DTH hammers, or any 
combination of those equipment, could occur. Such occurrences are 
anticipated to be infrequent, will be for short durations on any given 
day, and ADOT anticipates that no more than two hammers will be 
operated concurrently. Simultaneous use of two hammers or DTH systems 
could occur at the same project site, or at two different, but nearby 
project sites. Simultaneous use of hammers could result in increased 
SPLs and harassment zone sizes given the proximity of the component 
driving sites and the physical rules of decibel addition. ADOT 
anticipates that concurrent use of two hammers producing continuous 
noise could occur on 44 days, which is half the anticipated number of 
days of construction (91 days) and represents complete overlap between 
the two contracts and/or represents use of two hammers by a single 
contractor. Although it is unlikely that overlap will be complete, ADOT 
anticipates, and NMFS concurs, this scenario represents the potential 
worst case scenario, given that a more accurate estimate is not 
possible, and concurrent operation of hammers will be incidental. Given 
that the use of more than one hammer for pile installation on the same 
day (whether simultaneous or not) will increase the number of piles 
installed per day, this is anticipated to result in a reduction of the 
total number of days of pile installation. Table 5 shows how potential 
scenarios would reduce the total number of pile driving days and weeks. 
However, as described in the Marine Mammal Occurrence and Take 
Calculation and Estimation section below, ADOT has conservatively 
calculated take with the assumption that pile driving will occur on all 
91 days.

 Table 5--Calculated Reduction of Pile Driving Days Based on Percentage of Project Days With Two Hammers in Use
----------------------------------------------------------------------------------------------------------------
                                                   Days of work
                                      Days of        completed    Remaining days   Total number
         Percent overlap              overlap     during overlap   of work with     of days of     Weeks of work
                                                    (2 hammers)    single hammer       work
----------------------------------------------------------------------------------------------------------------
0...............................             0.0             0.0            91.0            91.0            15.2
10..............................             9.1            18.2            72.8            81.9            13.7
20..............................            18.2            36.4            54.6            72.8            12.1
30..............................            27.3            54.6            36.4            63.7            10.6

[[Page 15393]]

 
40..............................            36.4            72.8            18.2            54.6             9.1
50..............................            45.5            91.0             0.0            45.5             7.6
----------------------------------------------------------------------------------------------------------------

    NMFS (2018b) handles overlapping sound fields created by the use of 
more than one hammer differently for impulsive (impact hammer and Level 
A harassment zones for drilling with a DTH hammer) and continuous sound 
sources (vibratory hammer and Level B harassment zones for drilling 
with a DTH hammer; Table 6) and differently for impulsive sources with 
rapid impulse rates of multiple strikes per second (DTH) and slow 
impulse rates (impact hammering) (NMFS 2021). It is unlikely that the 
two impact hammers will strike at the same instant, and therefore, the 
SPLs will not be adjusted regardless of the distance between impact 
hammers. In this case, each impact hammer will be considered to have 
its own independent Level A harassment and Level B harassment zones.
    When two DTH hammers operate simultaneously their continuous sound 
components overlap completely in time. When the Level B isopleth of one 
DTH sound source encompasses the isopleth of another DTH sound source, 
the sources are considered additive and combined using the following 
rules (Table 7). The method described below was based on one created by 
Washington State Department of Transportation (WSDOT) and has been 
updated and modified by NMFS (WSDOT 2020). For addition of two 
simultaneous DTH hammers, the difference between the two SSLs is 
calculated, and if that difference is between 0 and 1 dB, 3 dB are 
added to the higher SSL; if difference is between 2 or 3 dB, 2 dB are 
added to the highest SSL; if the difference is between 4 to 9 dB, 1 dB 
is added to the highest SSL; and with differences of 10 or more 
decibels, there is no addition.
    When two continuous noise sources, such as vibratory hammers, have 
overlapping sound fields, there is potential for higher sound levels 
than for non-overlapping sources.
    When two or more vibratory hammers are used simultaneously, and the 
isopleth of one sound source encompasses the isopleth of another sound 
source, the sources are considered additive and source levels are 
combined using the rules in Table 6, similar to that described above 
for DTH.

                                   Table 6--Rules for Combining Sound Source Levels Generated During Pile Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
         Hammer types               Difference in SSL                       Level A zones                                  Level B zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory, Impact.............  Any......................  Use impact zones..............................  Use largest zone.
Impact, Impact................  Any......................  Use zones for each pile size and number of      Use zone for each pile size.
                                                            strikes.
Vibratory, Vibratory or DTH,    0 or 1 dB................  Add 3 dB to the higher source level...........  Add 3 dB to the higher source level
 DTH.                           2 or 3 dB................  Add 2 dB to the higher source level...........  Add 2 dB to the higher source level.
                                4 to 9 dB................  Add 1 dB to the higher source level...........  Add 1 dB to the higher source level.
                                10 dB or more............  Add 0 dB to the higher source level...........  Add 0 dB to the higher source level.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    During pile driving, it is common for pile installation to start 
and stop multiple times as each pile is adjusted and its progress is 
measured and documented, though as stated above, for short durations, 
it is anticipated that multiple hammers could be in use simultaneously. 
Following an approach modified from WSDOT in their Biological 
Assessment manual (WSDOT 2020) and described in Table 7, decibel 
addition calculations were carried out for possible combinations of 
pile driving and DTH throughout the project area. The source levels 
included in Table 7 are used to estimate the Level A harassment zones 
and the Level B harassment zones.

Table 7--Combined SSLs (dB at 10 m) Generated During Pile Installation and Removal for Combinations of Two Pieces of Equipment: Impact Hammer, Vibratory
                                                             Hammer, and Down-the-Hole Drill
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Method
                                         Vibratory (RMS)
                                            DTH (RMS)
                                            DTH (SEL)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Pile diameter            20         24         30          8         24         30          8         24         30
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  SSL        161        161        162        167        167        167        144        159        164
Vibratory (RMS)................         20        161        164        164        165        168        168        168  .........  .........  .........
                                        24        161        164        164        165        168        168        168  .........  .........  .........
                                        30        162        165        165        165        168        168        168  .........  .........  .........
DTH (RMS)......................          8        167        168        168        168        170        170        170  .........  .........  .........
                                        24        167        168        168        168        170        170        170  .........  .........  .........
                                        30        167        168        168        168        170        170        170  .........  .........  .........
DTH (SEL)......................          8        144  .........  .........  .........  .........  .........  .........        147        159        164
                                        24        159  .........  .........  .........  .........  .........  .........        159        162        165
                                        30        164  .........  .........  .........  .........  .........  .........        164        165        167
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 15394]]

    No addition is warranted for impact pile driving in combination 
with vibratory or impact pile driving or DTH (NMFS 2021).

Level B Harassment Zones

    Transmission loss (TL) is the decrease in acoustic intensity as an 
acoustic pressure wave propagates out from a source. TL parameters vary 
with frequency, temperature, sea conditions, current, source and 
receiver depth, water depth, water chemistry, and bottom composition 
and topography. The general formula for underwater TL is:

TL = B * Log10 (R1/R2),

Where:

TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement

    The recommended TL coefficient for most nearshore environments is 
the practical spreading value of 15. This value results in an expected 
propagation environment that will lie between spherical and cylindrical 
spreading loss conditions, which is the most appropriate assumption for 
ADOT's planned activity in the absence of specific modelling.
    All Level B harassment isopleths are reported in Table 8 and Table 
9 below. It should be noted that based on the geography of Tongass 
Narrows and the surrounding islands, sound will not reach the full 
distance of the Level B harassment isopleth in most directions. 
Generally, due to interaction with land, only a thin slice of the 
possible area is ensonified to the full distance of the Level B 
harassment isopleth.
    The size of the Level B harassment zone during concurrent operation 
of two vibratory or DTH hammers will depend on the combination of sound 
sources and the decibel addition of two hammers producing continuous 
noise. Table 8 shows the distances to Level B harassment isopleths 
during simultaneous hammering from two sources, based on the combined 
SSL. Because the calculated Level B harassment isopleths for two 
sources are dependent upon the combined SSL, the Level B harassment 
zone for each combined sound source level included in Table 8 is 
consistent, regardless of the equipment combination. Please refer to 
Table 7 to determine which sound sources apply to each combined SSL.
    As noted previously, pile installation often involves numerous 
stops and starts of the hammer for each pile. Therefore, decibel 
addition is applied only when the adjacent continuous sound sources 
experience overlapping sound fields, which generally requires close 
proximity of driving locations.

   Table 8--Level B Harassment Isopleths for Multiple Vibratory Hammer
                                Additions
------------------------------------------------------------------------
                                                               Level B
                                                              harassment
                     Combined SSL (dB)                         isopleth
                                                               (m) \a\
------------------------------------------------------------------------
164........................................................        8,577
165........................................................       10,000
166........................................................       11,659
167........................................................       13,594
168........................................................       15,849
169........................................................       18,478
170........................................................       21,544
------------------------------------------------------------------------
\a\ These larger zones are truncated to the southeast by islands, which
  prevent propagation of sound in that direction beyond the confines of
  Tongass Narrows. To the northwest of Tongass Narrows, combined sound
  levels that exceed 167 dB rms extend into Clarence Strait before
  attenuating to sound levels that are anticipated to be below 120 dB
  rms.


 Table 9--Level B Harassment Isopleths for Single Hammer Use by Activity
                              and Pile Size
------------------------------------------------------------------------
                                                               Level B
                                                              harassment
              Activity                    Pile diameter        isopleth
                                                                 (m)
------------------------------------------------------------------------
Vibratory Installation.............  30-inch...............        6,310
                                     24-inch...............        5,412
                                     20-inch...............
Vibratory Removal..................  24-inch...............
DTH Rock Sockets...................  30-inch...............       13,594
                                     24-inch...............
DTH Tension Anchor/Micropile.......  8-inch................
Impact Installation................  30-inch...............        2,154
                                     24-inch...............        1,000
                                     20-inch...............        1,000
------------------------------------------------------------------------

Level A Harassment Zones

    When the NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimate of takes by Level A harassment. However, these tools offer 
the best way to predict appropriate isopleths when more sophisticated 
3D modeling methods are not available, and NMFS continues to develop 
ways to quantitatively refine these tools, and will qualitatively 
address the output where appropriate. For stationary sources such as 
pile driving or removal and DTH using any of the methods discussed 
above, NMFS' User Spreadsheet predicts the closest distance at which, 
if a marine mammal remained at that distance the whole duration of the 
activity, it will incur PTS. Inputs used in the User Spreadsheet are 
reported in Table 10 and Table 11, and the resulting isopleths are 
reported below in Table 12 and Table 13. Pile installation and removal 
can occur at variable rates, from a few minutes one day to many hours 
the next. ADOT anticipates that one permanent pile will be installed 
per day on 27 non-consecutive days, two temporary piles will be 
installed per day on 10 non-consecutive days, and two temporary piles 
will be removed per day on 10 days.

[[Page 15395]]



                                              Table 10--NMFS User Spreadsheet Inputs For Single Hammer Use
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Vibratory
                                 Vibratory     pile driver     Vibratory                                           Impact pile  Impact pile  Impact pile
                                pile driver   (installation   pile driver     DTH rock     DTH rock   DTH tension  driver (30-  driver (24-  driver (20-
        Equipment type         (installation   and removal   (installation  sockets (30- sockets (24-  anchor (8-   inch steel   inch steel   inch steel
                                 of 30-inch     of 24-inch     of 20-inch      inch)        inch)        inch)        piles)       piles)       piles)
                                steel piles)   steel piles)   steel piles)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet tab used                  (A.1)          (A.1)          (A.1)         (E.2)        (E.2)        (E.2)        (E.1)        (E.1)        (E.1)
                                  vibratory      vibratory      vibratory      DTH pile     DTH pile     DTH pile  impact pile  impact pile  impact pile
                               pile driving   pile driving   pile driving       driving      driving      driving      driving      driving      driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
Weighting Factor Adjustment             2.5            2.5            2.5             2            2            2            2            2            2
 (kHz).......................
SSL..........................       \a\ 162        \a\ 161        \a\ 161       \b\ 164      \b\ 159      \b\ 144      \b\ 181      \b\ 177      \b\ 177
Activity duration (hours)                 1              1              1          1-10         1-10          2-4  ...........  ...........  ...........
 within 24 hours.............
Number of piles per day......             1              1              1             1            1            1            1            1            1
Strike rate strikes per        .............  .............  .............           15           15        25.83  ...........  ...........  ...........
 second......................
Number of strikes per pile...  .............  .............  .............  ...........  ...........  ...........           50           50           50
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Propagation loss coefficient in all cases is 15. Duration estimates for DTH are based on assumption of multiple rock sockets and tension anchors
  being installed each day, with the maximum duration time for installation per day predicted to be 10 hours for rock socket DTH and 4 hours for tension
  anchor DTH. For specifics regarding the number of strikes and number of piles that will be used in a given situation, please refer to Table 1 in the
  notice of proposed IHA (87 FR 5980; February 2, 2022).
\a\ dB rms at 10m.
\b\ dB SEL at 10m.

    Regarding implications for Level A harassment zones when two 
vibratory hammers are operating concurrently, given the small size of 
the estimated Level A harassment isopleths for all hearing groups 
during vibratory pile driving, the zones of any two hammers are not 
expected to overlap. Therefore, compounding effects of multiple 
vibratory hammers operating concurrently are not anticipated, and NMFS 
has treated each source independently.
    Regarding implications for Level A harassment zones when one 
vibratory hammer and one DTH hammer are operating concurrently, 
combining isopleths for these sources is difficult for a variety of 
reasons. First, vibratory pile driving relies upon non-impulsive PTS 
thresholds, while DTH/rock hammers use impulsive thresholds. Second, 
vibratory pile driving account for the duration to drive a pile, while 
DTH account for strikes per pile. Thus, it is difficult to measure 
sound on the same scale and combine isopleths from these impulsive and 
non-impulsive, continuous sources. Therefore, NMFS has treated each 
source independently at this time.
    Regarding the operation of two DTH hammers concurrently, since DTH 
hammers are capable of multiple strikes per second, there is potential 
for multiple DTH/rock hammer sources' isopleths to overlap in space and 
time (a higher strike rate indicates a greater potential for overlap). 
Therefore, NMFS has calculated distances to Level A harassment 
isopleths, by hearing group for simultaneous use of two DTH hammers 
(Table 13), using NMFS' User Spreadsheet. The inputs for these 
calculations are outlined in Table 11. When the Level A isopleth of one 
DTH sound source encompasses the isopleth of another DTH sound source, 
the sources are considered additive and combined using the rules in 
Table 7 as described above. The number of piles per day is altered to 
reflect only a single pile for all those that overlap in space and time 
(i.e., no double counting of overlapping piles). The maximum strike 
rate and duration of the two DTH systems is used in the User 
Spreadsheet calculations.

 Table 11--NMFS User Spreadsheet Inputs for Simultaneous Use of Two DTH
                                 Hammers
------------------------------------------------------------------------
          Spreadsheet tab used                (E.2) DTH pile driving
------------------------------------------------------------------------
Weighting Factor Adjustment (kHz)......  2.
SSL(dB SEL at 10m) \a\
    8-in pile/8-in pile................  147.
    8-in pile, 24-in pile..............  159.
    8-in pile, 30-in pile..............  164.
    24-in pile, 24-in pile.............  162.
    24-in pile, 30-in pile.............  165.
    30-in pile, 30-in pile.............  167.
Activity duration (minutes) within 24    60, 120, 180 or 240 \c\.
 hours \b\.
Number of piles per day \b\............  1.
Strike rate (strikes per second).......  15 or 25.83 \d\.
------------------------------------------------------------------------
\a\ SSL reflects the combined SSLs calculated in Table 7.
\b\ ADOT anticipates that DTH could occur at one site for up to 10 hours
  (600 minutes) per day, and overlap between two sites could occur for
  up to 4 hours (240 minutes) per day. Since the potential overlap in
  sources is accounted for in the SSL adjustment, and the total
  potential duration (even with two hammers) is accounted for in the
  ``Activity duration (minutes) within 24 hours,'' the ``Number of piles
  per day'' is assumed to be 1.
\c\ Duration will vary.
\d\ 25.83 for combinations that include 8-in piles. 15 for all other
  combinations.

    Level A harassment thresholds for impulsive sound sources (impact 
pile driving and DTH) are defined for both SELcum and Peak SPL with the 
threshold that results in the largest modeled isopleth for each marine 
mammal hearing group used to establish the Level A harassment isopleth. 
In this project, Level A harassment isopleths based on cumulative sound 
exposure level (SELcum) were always larger than those based on Peak SPL 
(for both single hammer use and simultaneous use of two hammers). It 
should be noted that there is a duration component when calculating the 
Level A harassment isopleth based on SELcum, and this duration depends 
on the number of piles that will be driven in a day and strikes per 
pile. For some activities, ADOT plans to drive variable numbers of 
piles per day throughout the project (See ``Average Piles per Day 
(Range)'' in Table 1 in the notice of proposed IHA (87 FR 5980; 
February 2, 2022)), and determine at the beginning of each pile driving 
day, the maximum number or duration piles will be driven that day. 
Here, this flexibility has been accounted for by modeling multiple 
durations for the activity, and determining the relevant isopleths.

[[Page 15396]]



             Table 12--Distances to Level A Harassment Isopleths, by Hearing Group, and Area of Level A Harassment Zones, for Single Hammer Use During Pile Installation and Removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                             Level A harassment isopleth  (m)                       Level A
                                                                            Minutes per pile or strikes per -----------------------------------------------------------------  harassment areas
                Activity                          Pile diameter(s)                        pile                                                                                   (km \2\) all
                                                                                                                  LF           MF           HF           PW           OW      hearing groups \a\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation..................  30-inch.........................  60 minutes.....................            8            1           12            5            1                <0.1
                                          24-inch \b\.....................  60 minutes.....................            7            1           11            5            1                <0.1
                                          20-inch.........................  60 minutes.....................            7            1           11            5            1                <0.1
Vibratory Removal.......................  24-inch.........................  60 minutes.....................            7            1           11            5            1                <0.1
DTH Rock Sockets........................  30-inch.........................  60 minutes.....................          773           28          920          414           31                <0.9
                                                                            300 minutes....................        2,258           81        2,690        1,209           88                <3.5
                                                                            600 minutes....................        3,584          128        4,269        1,918          140                <6.6
                                          24-inch.........................  60 minutes.....................          359           13          427          192           15                <0.2
                                                                            300 minutes....................        1,048           38        1,249          561           41                <1.4
                                                                            600 minutes....................        1,664           60        1,982          891           65                <2.4
DTH Tension Anchor......................  8-inch..........................  120 minutes....................           82            3           98           44            4                <0.1
                                                                            240 minutes....................          130            5          155           70            6                <0.1
Impact Installation.....................  30-inch.........................  50 strikes.....................          100            4          119           54            4                <0.1
                                          24-inch.........................  50 strikes.....................           54            2           65           29            3                <0.1
                                          20-inch.........................  50 strikes.....................           54            2           65           29            3                <0.1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Please refer to Table 6-4 of ADOT's IHA application for hearing group-specific areas.
\b\ Includes vibratory installation and removal.


                      Table 13--Distances to Level A Harassment Isopleths, by Hearing Group for Simultaneous Use of Two DTH Hammers
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Level A harassment isopleth (m)
                  Activity combination                       Duration    -------------------------------------------------------------------------------
                                                                                LF              MF              HF              PW              OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 8-in pile....................................              60              82               3              98              44               3
                                                                     120             130               5             155              70               5
                                                                     180             170               6             202              91               7
                                                                     240             206               7             245             110               8
8-in pile, 24-in pile...................................              60             515              18             613             276              20
                                                                     120             817              29             974             437              32
                                                                     180           1,071              38           1,276             573              42
                                                                     240           1,297              46           1,545             694              51
8-in pile, 30-in pile...................................              60           1,109              40           1,321             594              43
                                                                     120           1,761              63           2,097             942              69
                                                                     180           2,307              82           2,748           1,235              90
                                                                     240           2,796              99           3,329           1,496             109
24-in pile, 24-in pile..................................              60             568              20             677             304              22
                                                                     120             902              32           1,074             483              35
                                                                     180           1,181              42           1,407             632              46
                                                                     240           1,431              51           1,705             766              56
24-in pile, 30-in.......................................              60             900              32           1,072             482              35
                                                                     120           1,429              51           1,702             765              56
                                                                     180           1,873              67           2,230           1,002              73
                                                                     240           2,268              81           2,702           1,214              88
30-in pile, 30-in pile..................................              60           1,224              44           1,458             655              48
                                                                     120           1,943              69           2,314           1,040              76
                                                                     180           2,545              91           3,032           1,362              99
                                                                     240           3,084             110           3,673           1,650             120
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Regarding implications for impact hammers used in combination with 
a vibratory hammer or DTH drill, the likelihood of these multiple 
sources' isopleths to completely overlap in time is slim primarily 
because impact pile driving is intermittent. Furthermore, non-
impulsive, continuous sources rely upon non-impulsive TTS/PTS 
thresholds, while impact pile driving uses impulsive thresholds, making 
it difficult to calculate isopleths that may overlap from impact 
driving and the simultaneous action of a non-impulsive continuous 
source or one with multiple strikes per second. Thus, with such slim 
potential for multiple different sources' isopleths to overlap in space 
and time, specifications should be entered as ``normal'' into the User 
Spreadsheet for each individual source separately.

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. Additionally, we describe how the occurrence information 
is brought together to produce a quantitative take estimate for each 
phase. A summary of the estimated take, including as a percentage of 
population for each of the species, is shown in Table 14.

Steller Sea Lion

    Steller sea lion abundance in the Tongass Narrows area is not well 
known. No systematic studies of Steller sea lions have been conducted 
in or near the Tongass Narrows area. Steller sea lions are known to 
occur year-round and local residents report observing Steller sea lions 
approximately once or twice per week (based on communication outlined 
in Section 6 of ADOT's IHA application). Abundance

[[Page 15397]]

appears to increase during herring runs (March to May) and salmon runs 
(July to September). Group sizes may reach up to 6 to 10 individuals 
(Freitag 2017 as cited in 83 FR 37473; August 1, 2018), though groups 
of up to 80 individuals have been observed (HDR, Inc. 2003).
    ADOT conservatively estimates that one group of 10 Steller sea 
lions may be present in the project area each day, but this occurrence 
rate may as much as double (20 Steller sea lions per day) during 
periods of increased abundance associated with the herring and salmon 
runs (March to May and July to September). Therefore, ADOT anticipates 
that two large groups (20 individuals) may be taken by Level B 
harassment each day during these months. To be conservative, we assume 
all 91 days of work could be completed during these months of increased 
abundance and thus estimate 1,820 potential takes by Level B harassment 
of Steller sea lions in Tongass Narrows (i.e., 2 groups of 10 sea lions 
per day x 91 construction days = 1,820 takes by Level B harassment; 
Table 14).
    ADOT estimates that simultaneous use of two hammers (any 
combination) could occur on up to 44 days during the project. On those 
days, Level B harassment zones will extend into Clarence Strait. 
Steller sea lions are known to swim across Clarence Strait and to use 
offshore areas with deeper waters, although no estimates of at-sea 
density or abundance in Clarence Strait are available. Therefore, ADOT 
has conservatively estimated, and NMFS concurs, that during the 44 days 
with potential simultaneous use of two hammers, a group of 10 Steller 
sea lions may occur in the portion of the Level B harassment zone in 
Clarence Strait each day (one group of 10 sea lions per day x 44 days = 
440 individuals). Therefore, the preliminary sum of estimated takes by 
Level B harassment of Steller sea lions between Tongass Narrows and 
Clarence Strait is 2,260 (1,820 + 440 = 2,260 takes by Level B 
harassment).
    The largest Level A harassment zone for otariid pinnipeds could 
extend 140 m from the noise source for 10 hours of DTH using a single 
hammer, or 120m from the noise source for 4 hours of DTH using two 
hammers for 30-in piles simultaneously. (As noted previously, ADOT 
estimates that simultaneous use of any two hammer types will occur on 
no more than 44 days). Zones for shorter durations and other activities 
will be smaller (Table 12). For some DTH activities, the estimated 
Level A harassment zone is larger than the shutdown zone, and 
therefore, some Level A harassment could occur. Further, while 
unlikely, it is possible that a Steller sea lion could enter a shutdown 
zone without detection given the various obstructions along the 
shoreline, and remain in the zone long enough to be taken by Level A 
harassment before being observed and a shutdown occurring. ADOT 
therefore requested, and NMFS authorized, one take by Level A 
harassment on each of the 91 construction days (91 takes by Level A 
harassment). Authorized take by Level B harassment was calculated as 
the total calculated Steller sea lion takes by Level B harassment minus 
the takes by Level A harassment (2,260 takes-91 takes by Level A 
harassment) for a total of 2,169 takes by Level B harassment. 
Therefore, ADOT requested, and NMFS authorized, 91 takes of Steller sea 
lion by Level A harassment and 2,169 takes of Steller sea lion by Level 
B harassment (2,260 total takes of Steller sea lion; Table 14).

Harbor Seal

    Harbor seal densities in the Tongass Narrows area are not well 
known. No systematic studies of harbor seals have been conducted in or 
near Tongass Narrows. They are known to occur year-round with little 
seasonal variation in abundance (Freitag 2017 as cited in 83 FR 37473; 
August 1, 2018) and local experts estimate that there are about 1 to 3 
harbor seals in Tongass Narrows every day, in addition to those that 
congregate near the seafood processing plants and fish hatcheries. NMFS 
has indicated that the maximum group size in Tongass Narrows is three 
individuals (83 FR 22009; May 11, 2018); however, ADOT monitoring in 
March 2021 observed several groups of up to 5 individuals. Based on 
this knowledge, the expected maximum group size in Tongass Narrows is 
five individuals. Harbor seals are known to be curious and may approach 
novel activity. For these reasons ADOT conservatively estimates that up 
to two groups of 5 harbor seals per group could be taken by Level B 
harassment due to project-related underwater noise each construction 
day for a total of 910 takes by Level B harassment of harbor seal in 
Tongass Narrows (i.e., 2 groups of 5 harbor seals per day x 91 
construction days = 910 total takes by Level B harassment of harbor 
seal; Table 14).
    As noted above, ADOT estimates that simultaneous use of two hammers 
(any combination) could occur on up to 44 days during the project. On 
those days, Level B harassment zones will extend into Clarence Strait. 
Harbor seals are known to swim across Clarence Strait, although no 
estimates of at-sea density or abundance in Clarence Strait are 
available. It is likely that harbor seal abundance in Clarence Strait 
is lower than in Tongass Narrows, as harbor seals generally prefer 
nearshore waters. Therefore, ADOT has conservatively estimated, and 
NMFS concurs, that during the 44 days with potential simultaneous use 
of two hammers, a group of 5 harbor seals may occur in the portion of 
the Level B harassment zone in Clarence Strait each day (one group of 5 
harbor seals per day x 44 days = 220 individuals). Therefore, the sum 
of total estimated takes by Level B harassment of harbor seals between 
Tongass Narrows and Clarence Strait is 1,130 (910 + 220 = 1,130 takes 
by Level B harassment).
    The largest Level A harassment zone for harbor seals could extend 
1,918 m from the noise source for 10 hours of DTH using a single 
hammer, or 1,640 m from the noise source for 4 hours of DTH using two 
hammers for 30-in piles simultaneously. (As noted previously, ADOT 
estimates that simultaneous use of any two hammer types will occur on 
no more than 44 days). Zones for shorter durations and other activities 
will be smaller (Table 12). Due to practicability concerns, NMFS is 
requiring a 200 m shutdown zone for harbor seals during 24-in and 30-in 
DTH activities (Table 15). Therefore, for some DTH activities, the 
estimated Level A harassment zone is larger than the shutdown zone, and 
therefore, some Level A harassment could occur. Harbor seals may enter 
and remain within the area between the Level A harassment zone and the 
shutdown zone for a duration long enough to be taken by Level A 
harassment. Additionally, while unlikely, it is possible that a harbor 
seal could enter a shutdown zone without detection given the various 
obstructions along the shoreline, and remain in the zone for a duration 
long enough to be taken by Level A harassment before being observed and 
a shutdown occurring.
    To calculate take by Level A harassment, ADOT first calculated the 
ratio of the maximum Level A harassment isopleth for 30-in DTH using a 
single hammer minus the shutdown zone isopleth (1,918 m-200 m shutdown 
zone = 1,718 m) to the Level B harassment zone isopleth (13,594 m; 
1,718 m/13,594 m = 0.1264). ADOT multiplied the resulting ratio by the 
total potential take in Tongass Narrows, resulting in 116 takes by 
Level A harassment (i.e., 910 takes by Level B harassment x 0.1264 = 
116 takes by Level A harassment). NMFS reviewed, and concurs with and 
adopts this method. (Potential operation of two DTH hammers for 24-in/
30-in or 30-in/

[[Page 15398]]

30-in pile combinations would result in larger Level A harassment 
isopleths than 1,918 m, however, such concurrent work will rarely 
occur, if at all, and therefore, NMFS expects that calculating Level A 
harassment take using those zones would be overly conservative and 
unrealistic. Moreover, since the method used above assumes 30-inch DTH 
on all days it provided a precautionary cushion since activities with 
smaller Level A harassment zone sizes will occur on many days.) 
Authorized take by Level B harassment was calculated as the total 
calculated harbor seal takes by Level B harassment minus the takes by 
Level A harassment (1,130 takes-116 takes by Level A harassment) for a 
total of 1,014 takes by Level B harassment. ADOT therefore requested, 
and NMFS authorized, 116 takes of harbor seal by Level A harassment and 
1,014 takes of harbor seal by Level B harassment (1,130 total takes of 
harbor seal; Table 14).

Harbor Porpoise

    Harbor porpoises are non-migratory; therefore, our occurrence 
estimates are not dependent on season. Freitag (2017 as cited in 83 FR 
37473; August 1, 2018) observed harbor porpoises in Tongass Narrows 
zero to one time per month. Harbor porpoises observed in the project 
vicinity typically occur in groups of one to five animals with an 
estimated maximum group size of eight animals (83 FR 37473, August 1, 
2018, Solstice 2018). ADOT's 2020 and 2021 monitoring program in 
Tongass Narrows did not result in sightings of this species; however, 
ADOT assumes an occurrence rate of one group per month in the following 
take estimations. For our analysis, we are considering a group to 
consist of five animals. Based on Freitag (2017), and supported by the 
reports of knowledgeable locals as described in ADOT's application, 
ADOT estimates that one group of five harbor porpoises could enter 
Tongass Narrows and potentially taken by Level B harassment due to 
project-related noise each month for a total of 15 potential harbor 
porpoise takes by Level B harassment in Tongass Narrows (i.e., 1 group 
of 5 individuals x 3 months (91 days) = 15 harbor porpoises).
    As noted above, ADOT estimates that simultaneous use of two hammers 
(any combination) could occur on up to 44 days during the project. On 
those days, the Level B harassment zone will extend into Clarence 
Strait. Harbor porpoises are known to swim across Clarence Strait and 
to use other areas of deep, open waters. Dahlheim et al. (2015) 
estimated a density of 0.02 harbor porpoises/km\2\ in an area that 
encompasses Clarence Strait. ADOT estimates, and NMFS concurs that 
during the 44 days with potential simultaneous use of two hammers, 17 
harbor porpoises (0.02 harbor porpoises/km\2\ x 18.5 km\2\ x 44 days = 
17 harbor porpoises) may occur in the portion of the Level B harassment 
zone in Clarence Strait during the project (though ADOT and NMFS 
anticipate that this is a conservative estimate, given the entire 18.5 
km\2\ area will rarely be ensonified above the Level B harassment 
threshold). Therefore, the sum of total estimated takes by Level B 
harassment of harbor porpoise between Tongass Narrows and Clarence 
Strait is 32 (15 + 17 = 32 takes by Level B harassment).
    The largest Level A harassment zone for harbor porpoises extends 
4,269 m from the noise source for 10 hours of DTH using a single 
hammer, and 3,673 m from the noise source for 4 hours of DTH using two 
hammers for 30-in piles simultaneously. (As noted previously, ADOT 
estimates that simultaneous use of any two hammer types will occur on 
no more than 44 days). Zones for shorter durations and other activities 
will be smaller (Table 12). Due to practicability concerns, NMFS is 
requiring a 500 m shutdown zone for high frequency cetaceans during 24-
in and 30-in DTH activities. Therefore, for some DTH activities, the 
estimated Level A harassment zone is larger than the shutdown zone, and 
therefore, some Level A harassment could occur. Harbor porpoises may 
enter and remain within the area between the Level A harassment zone 
and the shutdown zone for a duration long enough to be taken by Level A 
harassment. Additionally, given the large size of required shutdown 
zones for some activities and the cryptic nature of harbor porpoises, 
it is possible that a harbor porpoise could enter a shutdown zone 
without detection and remain in the zone for a duration long enough to 
be taken by Level A harassment before being observed and a shutdown 
occurring.
    To calculate take by Level A harassment, ADOT first calculated the 
ratio of the maximum Level A harassment isopleth for 30-in DTH using a 
single hammer minus the shutdown zone isopleth (4,269 m-500 m = 3,769 
m) to the Level B harassment zone isopleth (13,594 m; 3,769/13,594 = 
0.2773). ADOT multiplied the resulting ratio by the total potential 
take in Tongass Narrows, resulting in 5 takes by Level A harassment 
(i.e., 15 takes by Level B harassment x 0.2773 = 5 takes by Level A 
harassment). NMFS reviewed and concurs with this method. (Potential 
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile 
combinations would result in larger Level A harassment isopleths than 
4,269 m, however, such concurrent work would rarely occur, if at all, 
and therefore, as described above, NMFS expects that calculating Level 
A harassment take using those zones is unnecessary.) Authorized take by 
Level B harassment was calculated as the total calculated harbor 
porpoise takes by Level B harassment minus the takes by Level A 
harassment (32 takes-5 takes by Level A harassment) for a total of 27 
takes by Level B harassment. ADOT therefore requested and NMFS 
authorized 5 takes by Level A harassment and 27 takes by Level B 
harassment (32 total takes of harbor porpoise; Table 14).

Dall's Porpoise

    Dall's porpoises are expected to only occur in the project area a 
few times per year. Their relative rarity is supported by Jefferson et 
al.'s (2019) presentation of historical survey data showing very few 
sightings in the Ketchikan area and conclusion that Dall's porpoise 
generally are rare in narrow waterways, like the Tongass Narrows. 
ADOT's monitoring program from 2020 and 2021 recorded one sighting of 6 
individuals over 23 days of observation, 16 days of observations with 
no sightings, and two sightings of 10 individuals in 14 days of 
observation; this equates to one sighting every approximately 17 days 
(DOT&PF 2020, 2021a, 2021b, 2021c, 2021d) or approximately two 
sightings per month. This species is non-migratory; therefore, the 
occurrence estimates are not dependent on season. ADOT anticipates that 
one large Dall's porpoise pod (12 individuals) may be present in the 
project area and exposed to project related underwater noise twice each 
month during 3 months of construction (91 days rounded to 3 months) for 
a total of 72 potential takes by Level B harassment in Tongass Narrows 
(i.e., 2 groups of 12 Dall's porpoises per month x 3 months = 72 
potential takes by Level B harassment).
    As noted above, ADOT estimates that simultaneous use of two hammers 
(any combination) could occur on up to 44 days during the project. On 
those days, the Level B harassment zone will extend into Clarence 
Strait, where Dall's porpoises are known to occur. Jefferson et al. 
(2019) estimated an average density of 0.19 Dall's porpoises/km\2\ in 
Southeast Alaska. ADOT estimates, and NMFS concurs, that during the 44 
days with potential simultaneous use of two hammers, 155 Dall's 
porpoises (0.19 Dall's porpoises/km\2\ x 18.5 km\2\ x 44 days = 155 
Dall's porpoises) may occur

[[Page 15399]]

in the portion of the Level B harassment zone in Clarence Strait during 
the project (though ADOT and NMFS anticipate that this is a 
conservative estimate, given the entire 18.5 km\2\ area will rarely be 
ensonified above the Level B harassment threshold). Therefore, the sum 
of total estimated takes by Level B harassment of harbor porpoise 
between Tongass Narrows and Clarence Strait is 227 (72 + 155= 227 takes 
by Level B harassment).
    The largest Level A harassment zone for Dall's porpoises extends 
4,269 m from the noise source for 10 hours of DTH using a single 
hammer, and 3,673 m from the noise source for 4 hours of DTH using two 
hammers for 30-in piles simultaneously. (As noted previously, ADOT 
estimates that simultaneous use of any two hammer types will occur on 
no more than 44 days.) Zones for shorter durations and other activities 
will be smaller (Table 12). Due to practicability concerns, NMFS 
proposes to require a 500 m shutdown zone for high frequency cetaceans 
during 24-in and 30-in DTH activities. Therefore, for some DTH 
activities, the estimated Level A harassment zone is larger than the 
shutdown zone, and therefore, some Level A harassment could occur. 
Dall's porpoises may enter and remain within the area between the Level 
A harassment zone and the shutdown zone and be exposed to sound levels 
for a duration long enough to be taken by Level A harassment. 
Additionally, given the large size of the required shutdown zones for 
some activities, it is possible that a Dall's porpoise could enter a 
shutdown zone without detection and remain in the zone for a duration 
long enough to taken by Level A harassment before being observed and a 
shutdown occurring.
    To calculate take by Level A harassment, ADOT first calculated the 
ratio of the maximum Level A harassment isopleth for 30-in DTH using a 
single hammer minus the shutdown zone isopleth (4,269 m-500 m = 3,769 
m) to the Level B harassment zone isopleth (13,594 m; 3,769/13,594 = 
0.2773). ADOT multiplied the resulting ratio by the total potential 
take in Tongass Narrows, resulting in 20 takes by Level A harassment 
(i.e., 72 takes by Level B harassment x 0.2773 = 20 takes by Level A 
harassment). NMFS revised and concurs with this method. (Potential 
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile 
combinations would result in larger Level A harassment isopleths than 
4,269 m, however, such concurrent work would rarely occur, if at all, 
and therefore, as described above, NMFS expects that calculating Level 
A harassment take using those zones is unnecessary.) Authorized take by 
Level B harassment was calculated as the total calculated Dall's 
porpoise takes by Level B harassment minus the takes by Level A 
harassment (227 takes-20 takes by Level A harassment) for a total of 
207 takes by Level B harassment. ADOT therefore requested and NMFS 
authorized 20 takes by Level A harassment, and 207 takes by Level B 
harassment (227 total takes of Dall's porpoise; Table 14).

Pacific White-Sided Dolphin

    Pacific white-sided dolphins do not generally occur in the shallow, 
inland waterways of Southeast Alaska. There are no records of this 
species occurring in Tongass Narrows, and it is uncommon for 
individuals to occur in the project area. However, historical sightings 
in nearby areas (Dahlheim and Towell 1994; Muto et al. 2018) and recent 
fluctuations in distribution and abundance mean it is possible the 
species could be present.
    To account for the possibility that this species could be present 
in the project area, ADOT conservatively estimates, and NMFS concurs, 
that one large group (92 individuals) of Pacific white-sided dolphins 
may be taken by Level B harassment in Tongass Narrows during the 
activity.
    As noted above, ADOT estimates that simultaneous use of two hammers 
(any combination) could occur on up to 44 days during the project. On 
those days, the Level B harassment zone will extend into Clarence 
Strait. However, no additional takes of Pacific white-sided dolphin are 
anticipated to occur due to simultaneous use of two hammers, given that 
Pacific white-sided dolphins are uncommon in the project area. 
Therefore, NMFS authorized 92 takes by Level B harassment of Pacific 
white-sided dolphins.
    ADOT did not request, nor did NMFS authorize take by Level A 
harassment for this activity given that Pacific white-sided dolphins 
are uncommon in the project area. Further, considering the small Level 
A harassment zones for mid-frequency cetaceans (Table 12 and Table 13) 
in comparison to the required shutdown zones, it is unlikely that a 
Pacific white-sided dolphin will enter and remain within the area 
between the Level A harassment zone and the shutdown zone for a 
duration long enough to be taken by Level A harassment.

Killer Whale

    Killer whales are observed in Tongass Narrows irregularly with 
peaks in abundance between May and July. During 7 months of 
intermittent marine mammal monitoring (October 2020-February 2021; May-
June 2021), there were five killer whale sightings in 4 months 
(November, February, May, June) totaling 22 animals; sightings occurred 
on 5 out of 88 days of monitoring (DOT&PF 2020, 2021a, 2021b, 2021c, 
2021d). Pod sizes ranged from two to eight animals (DOT&PF 2020, 2021a, 
2021b, 2021c, 2021d). Previous incidental take authorizations in the 
Ketchikan area have estimated killer whale occurrence in Tongass 
Narrows at one pod per month, except during the peak period of May to 
July when estimates have included two pods per month (Freitag 2017 as 
cited in 83 FR 37473; August 1, 2018 and 83 FR 34134; July 17, 2019).
    As noted above, ADOT estimates that simultaneous use of two hammers 
(any combination) could occur on up to 44 days during the project. On 
those days, the Level B harassment zone will extend into Clarence 
Strait. In estimating take by Level B harassment, ADOT assumed a pod 
size of 12 killer whales, that all 91 days of work will occur between 
May and July during the peaks in abundance, and that therefore, 2 pods 
may occur within the Level B harassment zone (including both Tongass 
Narrows and Clarence Strait) during each month of work, for a total of 
72 takes by Level B harassment (2 groups x 12 individuals x 3 months = 
72 killer whales). Therefore, ADOT estimates that a total of 72 killer 
whales may be taken by Level B harassment (i.e., 2 pods of 12 
individuals per month x 3 months (91 days) = 72 takes by Level B 
harassment). NMFS reviewed and concurs with this method, and authorized 
72 takes by Level B harassment of killer whale.
    ADOT did not request, nor did NMFS authorize take by Level A 
harassment of killer whales for this activity. Considering the small 
Level A harassment zones for mid-frequency cetaceans (Table 12 and 
Table 13) in comparison to the required shutdown zones, it is unlikely 
that a killer whale will enter and remain within the area between the 
Level A harassment zone and the shutdown zone for a duration long 
enough to be taken by Level A harassment.

Humpback Whale

    As discussed in the Description of Marine Mammals in the Area of 
Specified Activities section, locals have observed humpback whales an 
average of about once per week in Tongass Narrows, but there is 
evidence to suggest occurrence may be higher during some periods of the 
year. The December 19, 2019 Biological Opinion

[[Page 15400]]

stated that based on observations by local experts, approximately one 
group of two individuals will occur in Tongass Narrows during ADOT's 
activity two times per seven days during pile driving, pile removal, 
and DTH activities throughout the year. The assumption was based on 
differences in abundance throughout the year, recent observations of 
larger groups of whales present during summer, and a higher than 
average frequency of occurrence in recent months (NMFS 2019). ADOT's 
2020 and 2021 monitoring program documented a similar sighting rate, 
with 30 humpback whale sightings over 53 days of in-water pile driving; 
some of the sightings were believed to be repeated sightings of the 
same individual (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). ADOT 
therefore predicts, and NMFS concurs, that one group of two individuals 
may occur within the Level B harassment zones twice per week during the 
planned activities. As noted previously, ADOT estimates that pile 
driving will occur over the course of 91 days (13 weeks). Therefore, 
ADOT estimates, and NMFS concurs that 52 takes by Level B harassment of 
humpback whales (1 group of 2 individuals x 2 groups per week x 13 
weeks = 52 takes by Level B harassment) from the Central North Pacific 
stock may occur in Tongass Narrows.
    As noted above, ADOT estimates that simultaneous use of two hammers 
(any combination) could occur on up to 44 days during the project. On 
those days, the Level B harassment zone will extend into Clarence 
Strait. Local specialists estimated that approximately four humpback 
whales could pass through or near the portion of the Level B harassment 
zone in Clarence Strait each day. Therefore, ADOT estimates, and NMFS 
concurs, that during the 44 days with potential simultaneous use of two 
hammers, 176 takes by Level B harassment of humpback whale could occur 
in Clarence Strait (4 humpback whales x 44 days = 176 takes by Level B 
harassment). Therefore, the sum of total estimated takes by Level B 
harassment of humpback whale between Tongass Narrows and Clarence 
Strait is 228 (52 + 176 = 228 takes by Level B harassment), and NMFS 
authorized 228 takes by Level B harassment of humpback whale.
    As noted previously, Wade et al. (2021) estimates that 
approximately 2 percent of all humpback whales in Southeast Alaska and 
northern British Columbia are of the Mexico DPS, while all others are 
of the Hawaii DPS. However, NMFS has conservatively assumed here that 
6.1 percent of the total humpback population in Southeast Alaska is 
from the Mexico DPS (Wade et al. 2016). Therefore, of the 228 takes of 
humpback whale authorized, NMFS expects that a total of 14 takes will 
be of individuals from the Mexico DPS. NMFS expects that all other 
instances of take will be from the non-listed Hawaii DPS.
    Take by Level A harassment of humpback whales is neither 
anticipated nor authorized because of the expected effectiveness of the 
required monitoring and mitigation measures (see Mitigation Measures 
section below for more details). For all pile driving and DTH 
activities, the shutdown zone exceeds the calculated Level A harassment 
zone. Humpbacks are usually readily visible, and therefore, we expect 
protected species observers (PSOs) to be able to effectively implement 
the required shutdown measures prior to any humpback whales incurring 
PTS within Level A harassment zones.

Minke Whales

    Minke whales may be present in Tongass Narrows year-round. Their 
abundance throughout Southeast Alaska is very low, and anecdotal 
reports have not included minke whales near the project area. ADOT's 
monitoring program in Tongass Narrows also did not report any minke 
whale sightings. However, minke whales are distributed throughout a 
wide variety of habitats and could occur near the project area. Minke 
whales are generally sighted as solo individuals (Dahlheim et al. 
2009).
    As noted above, ADOT estimates that simultaneous use of two hammers 
(any combination) could occur on up to 44 days during the project. On 
those days, the Level B harassment zone will extend into Clarence 
Strait. Based on Freitag (2017; as cited in 83 FR 37473; August 1, 2018 
and 83 FR 34134; July 17, 2019), ADOT estimates that three individual 
minke whales may occur near or within the Level B harassment zone 
(including both Tongass Narrows and Clarence Strait) every four months. 
Based on that estimated occurrence rate, NMFS estimates that 3 minke 
whales may occur in the Level B harassment zone during the planned 
activities (occurring over approximately 3 months), and authorized 3 
takes by Level B harassment of minke whales (Table 14).
    The largest Level A harassment zone for minke whale extends 3,584 m 
from the noise source for 10 hours of DTH using a single hammer, and 
3,084 m from the noise source for 4 hours of DTH using two hammers for 
30-in piles simultaneously. (As noted previously, ADOT estimates that 
simultaneous use of any two hammer types will occur on no more than 44 
days.) Zones for shorter durations and other activities will be smaller 
(Table 13). NMFS required a 1,500 m shutdown zone for minke whales 
during 24-in and 30-in DTH activities. Therefore, for some DTH 
activities, the estimated Level A harassment zone is larger than the 
required shutdown zone, and Level A harassment could occur.
    To calculate take by Level A harassment, ADOT first calculated the 
ratio of the maximum Level A harassment isopleth for 30-in DTH using a 
single hammer minus the shutdown zone isopleth (3,584 m-1,500 m = 2,084 
m) to the Level B harassment zone isopleth (13,594 m; 2,084 m/13,594 m 
= 0.1533). ADOT multiplied the resulting ratio by the total potential 
take by Level B harassment, resulting in 1 take by Level A harassment 
(i.e., 3 takes by Level B harassment x 0.1533 = 1 take by Level A 
harassment). NMFS reviewed and concurs with this method. (Potential 
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile 
combinations would result in larger Level A harassment isopleths than 
4,269 m, however, such concurrent work would rarely occur, if at all, 
and therefore, as described above NMFS expects that calculating Level A 
harassment take using those zones is unnecessary.) Take by Level B 
harassment was calculated as the total potential minke whale takes by 
Level B harassment minus the takes by Level A harassment. ADOT 
therefore requested, and NMFS authorized 1 take by Level A harassment 
and 2 takes by Level B harassment (3 total takes of minke whale; Table 
14).

[[Page 15401]]



           Table 14--Authorized Take as a Percentage of Stock Abundance, by Stock and Harassment Type
----------------------------------------------------------------------------------------------------------------
                                                                  Authorized take
                                                 ------------------------------------------------   Percent of
            Species                 DPS/stock         Level A         Level B                          stock
                                                    harassment      harassment         Total
----------------------------------------------------------------------------------------------------------------
Steller sea lion..............  Eastern U.S.....              91           2,169           2,260             5.2
Harbor seal...................  Clarence Strait.             116           1,014           1,130             4.1
Harbor porpoise...............  Southeast Alaska               5              27              32             2.5
Dall's porpoise...............  Alaska..........              20             207             227             1.7
Pacific white-sided dolphin...  North Pacific...               0              92              92             0.3
                               ---------------------------------------------------------------------------------
Killer whale..................  Alaska Resident.               0              72              72         \a\ 3.1
                                West Coast                                                              \a\ 20.1
                                 Transient
                                Northern                                                                \a\ 23.8
                                 Resident
Humpback whale................  Central North                  0             228             228             2.3
                                 Pacific.
Minke whale...................  Alaska..........               1               2               3             N/A
----------------------------------------------------------------------------------------------------------------
\a\ Conservatively assumes that all 72 takes occur to each stock.

Mitigation Measures

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable 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. 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, we 
carefully consider 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 such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    Because of the need for an ESA Section 7 consultation for effects 
of the project on ESA listed humpback whales, there are a number of 
mitigation measures that go beyond, or are in addition to, typical 
mitigation measures we would otherwise require for this sort of 
project. However, these measures are typical for actions in the 
Ketchikan area. The mitigation measures included herein include 
measures that align with the 2019 Biological Opinion. ADOT must employ 
the following mitigation measures as included in the proposed IHA:
    <bullet> Avoid direct physical interaction with marine mammals 
during construction activity. If a marine mammal comes within 10 m of 
such activity, operations must cease and vessels must reduce speed to 
the minimum level required to maintain steerage and safe working 
conditions (note that NMFS expects that a 10 m shutdown zone is 
sufficient to avoid direct physical interaction with marine mammals, 
but ADOT conservatively proposed a 20 m shutdown zone to avoid physical 
interaction for in-water other than vessel transit);
    <bullet> Ensure that construction supervisors and crews, the 
monitoring team and relevant ADOT staff are trained prior to the start 
of all pile driving and DTH activity, 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;
    <bullet> 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;
    <bullet> For any marine mammal species for which take by Level B 
harassment has not been requested or authorized, in-water pile 
installation/removal and DTH will shut down immediately when the 
animals are sighted;
    <bullet> Employ PSOs and establish monitoring locations as 
described in the Marine Mammal Monitoring Plan and Section 5 of the 
IHA. The Holder must monitor the project area to the maximum extent 
possible based on the required number of PSOs, required monitoring 
locations, and environmental conditions. For all pile driving and 
removal at least three PSOs must be used;
    <bullet> The placement of the PSOs during all pile driving and 
removal and DTH activities will ensure that the entire shutdown zone is 
visible during pile installation;
    <bullet> Monitoring must take place from 30 minutes prior to 
initiation of pile driving or DTH activity (i.e., pre-clearance 
monitoring) through 30 minutes post-completion of pile driving or DTH 
activity;
    <bullet> If in-water work ceases for more than 30 minutes, ADOT 
will conduct pre-clearance monitoring of both the Level B harassment 
zone and shutdown zone;
    <bullet> 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 15 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;
    <bullet> If a marine mammal is observed entering or within the 
shutdown zones

[[Page 15402]]

indicated in Table 15, 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 15) or 15 minutes have passed without re-detection of the animal 
(30 minutes for humpback whales);
    <bullet> As required by the 2019 Biological Opinion, if waters 
exceed a sea state that restricts the PSOs' ability to make 
observations within the shutdown zone, in-water pile installation and 
removal will cease. Pile installation and removal will not be initiated 
or continue until the appropriate shutdown zone is visible in its 
entirety;
    <bullet> For humpback whales, if the boundaries of the harassment 
zone have not been monitored continuously during a work stoppage, the 
entire harassment zone will be surveyed again to ensure that no 
humpback whales have entered the harassment zone that were not 
previously accounted for;
    <bullet> In-water activities will take place only: Between civil 
dawn and civil dusk when PSOs can effectively monitor for the presence 
of marine mammals; during conditions with a Beaufort Sea State of 4 or 
less; when the entire shutdown zone and adjacent waters are visible 
(e.g., monitoring effectiveness is not reduced due to rain, fog, snow, 
etc.). Pile driving may continue for up to 30 minutes after sunset 
during evening civil twilight, as necessary to secure a pile for safety 
prior to demobilization for the evening. PSO(s) will continue to 
observe shutdown and monitoring zones during this time. The length of 
the post-activity monitoring period may be reduced if darkness 
precludes visibility of the shutdown and monitoring zones;
    <bullet> Vessel operators will implement the following required 
measures: Maintain a watch for marine mammals at all times while 
underway; remain at least and at least 91 m (100 yards (yd)) from all 
other listed marine mammals, travel at less than 5 knots (9 km/hr) when 
within 274 m (300 yd) of a whale; avoid changes in direction and speed 
when within 274 m (300 yd) of whales, unless doing so is necessary for 
maritime safety; not position vessel(s) in the path of whales, and will 
not cut in front of whales in a way or at a distance that causes the 
whales to change their direction of travel or behavior (including 
breathing/surfacing pattern); check the waters immediately adjacent to 
the vessel(s) to ensure that no whales will be injured when the 
propellers are engaged; adhere to the Alaska Humpback Whale Approach 
Regulations when transiting to and from the project site (see 50 CFR 
216.18, 223.214, and 224.103(b)); not allow lines to remain in the 
water, and not throw trash or other debris overboard, thereby reducing 
the potential for marine mammal entanglement; follow established 
transit routes and travel <10 knots while in the harassment zones; 
follow the speed limit within Tongass Narrows (7 knots for vessels over 
23 ft in length). If a whale's course and speed are such that it will 
likely cross in front of a vessel that is underway, or approach within 
91 m (100 yards (yd)) of the vessel, and if maritime conditions safely 
allow, the engine will be put in neutral and the whale will be allowed 
to pass beyond the vessel, except that vessels will remain 460 m (500 
yd) from North Pacific right whales; if a humpback whale comes within 
10 m (32.8 ft) of a vessel during construction, the vessel will reduce 
speed to the minimum level required to maintain safe steerage and 
working conditions until the humpback whale is at least 10 m (32.8 ft) 
away from the vessel; vessels are prohibited from disrupting the normal 
behavior or prior activity of a whale by any other act or omission.
    <bullet> ADOT 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; and
    <bullet> If take by Level B harassment reaches the authorized limit 
for an authorized species, pile installation will be stopped as these 
species approach the Level B harassment zone to avoid additional take 
of them.
    Further, on days when simultaneous use of two hammers producing 
continuous noise (two DTH hammers, one DTH and one vibratory hammer, or 
two vibratory hammers) is expected:
    <bullet> When combinations of one DTH hammer with a vibratory 
hammer or two DTH hammers are used simultaneously, each PSO of the two 
contractors will have three PSOs working and the PSO teams will work 
together to monitor the entire area;
    <bullet> One or more PSOs will be present at each construction site 
during in-water pile installation and removal so that Level A 
harassment zones and shutdown zones are monitored by a dedicated PSO at 
all times.
    <bullet> The ADOT environmental coordinator for the project will 
implement coordination between or among the PSO contractors. ADOT will 
include in the contracts that PSOs must coordinate, collaborate, and 
otherwise work together to ensure compliance with project permits and 
authorizations.
    The following specific mitigation measures will also apply to 
ADOT's in-water construction activities:
    Establishment of Level A Harassment Zones and Shutdown Zones--For 
all pile driving/removal and DTH activities, ADOT will establish a 
shutdown zone (Table 15). The purpose of a shutdown zone is generally 
to define an area within which shutdown of activity will occur upon 
sighting of a marine mammal (or in anticipation of an animal entering 
the defined area). Shutdown zones vary based on the activity type and 
duration and marine mammal hearing group (Table 15). For vibratory 
installation and removal and impact installation, shutdown zones will 
be based on the Level A harassment isopleth distances for each hearing 
group.
    ADOT anticipates that the daily duration of DTH use may vary 
significantly, with large differences in maximum zones sizes possible 
depending on the work planned for a given day. Given this uncertainty 
and concerns related to ESA-listed humpback whales, ADOT will utilize a 
tiered system to identify and monitor the appropriate Level A 
harassment zones and shutdown zones, based on the maximum expected DTH 
duration. At the start of any work involving DTH, ADOT will first 
determine whether DTH may occur at two sites concurrently or just at 
one site. If DTH may occur at two sites concurrently, then ADOT will 
implement the Level A harassment zones and shutdown zones associated 
with simultaneous DTH use of the relevant pile sizes (Table 13 and 
Table 15). If DTH may only occur at one site, ADOT will then determine 
the maximum duration of DTH possible that day (according to the defined 
duration intervals in Table 15), which will determine the appropriate 
Level A harassment isopleth for that day (Table 12 and Table 13). This 
Level A harassment zone and associated shutdown zone must be observed 
by PSO(s) for the entire work day or until it is determined that, given 
the duration of activity for the day, the Level A harassment isopleth 
cannot exceed the next lower Level A harassment isopleth size in Table 
12.
    Due to practicability concerns, shutdown zones for some species 
during some activities may be smaller than the Level A harassment 
isopleths (Table 15). The placement of PSOs during all pile

[[Page 15403]]

driving, pile removal, and DTH activities (described in detail in the 
Monitoring and Reporting section) will ensure that the entire shutdown 
zones are visible during pile installation.

                                       Table 15--Shutdown Zones and Level B Harassment Isopleths for Each Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          Shutdown distances (m)
                                                Minutes per   ------------------------------------------------------------------------------   Level B
            Activity              Pile size   pile or strikes       LF                                                                        harassment
                                     (in)         per pile      (humpback    LF (minke        MF           HF           PW           OW        isopleth
                                                                 whales)      whales)                                                            (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation.........           30  60 min.........           50                                 20                                      6,310
                                          24  60 min                                                                                               5,412
                                          20  60 min
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Removal..............           24  60 min
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH of Rock Sockets............           30  60 min.........          780        1,500           30          500          200           40       13,594
                                              120 min........        1,300                        50                                     50
                                              180 min........        1,700                        60                                     70
                                              240 min........        2,000                        70                                     80
                                              300 min........        2,300                        90                                     90
                                              360 min........        2,600                       100                                    100
                                              420 min........        2,900
                                              480 min........        3,100
                                              540 min........        3,400
                                              600 min........        3,600                       130                                    100
                                          24  60 min.........          360        1,500           20          500          200           20
                                              120 min........          570                        30                                     30
                                              180 min........          750                        30                                     30
                                              240 min........          910                        40                                     40
                                              300 min........        1,100                        40                                     50
                                              360 min........        1,200                        50                                     50
                                              420 min........        1,400                        50                                     60
                                              480 min........        1,500                        60                                     60
                                              540 min........        1,600                        60                                     70
                                              600 min........        1,700                        60                                     70
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH of Tension Anchor..........            8  120 min........           90           90           20          100           50           20
                                              240 min........          130          130                       160           70
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Installation............           30  50 strikes.....          100          100           20          120           60           20        2,154
                                          24  50 strikes.....           60           60                        70           30                     1,000
                                          20  50 strikes
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                   Table 16--Shutdown Zones, by Hearing Group for Simultaneous Use of Two DTH Hammers
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Level A harassment isopleth (m)
                  Activity combination                       Duration    -------------------------------------------------------------------------------
                                                             (minutes)          LF              MF              HF              PW              OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 8-in pile....................................              60              90              20             100              50              20
                                                                     120             130                             160              70
                                                                     180             170                             200             100
                                                                     240             210                             250             110
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 24-in pile...................................              60             520              20             500             200              20
                                                                     120             820              30                                              40
                                                                     180           1,080              40                                              50
                                                                     240           1,300              50                                              60
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 30-in pile...................................              60           1,110              40                                              50
                                                                     120           1,770              70                                              70
                                                                     180           2,310              90                                              90
                                                                     240           2,800             100                                             110
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in pile, 24-in pile..................................              60             570              20                                              30
                                                                     120             910              32                                              40
                                                                     180           1,190              42                                              50
                                                                     240           1,440              60                                              60
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in pile, 30-in.......................................              60             900              40                                              40
                                                                     120           1,430              60                                              60
                                                                     180           1,880              70                                              80
                                                                     240           2,270              90                                              90
--------------------------------------------------------------------------------------------------------------------------------------------------------
30-in pile, 30-in pile..................................              60           1,230              50                                              50
                                                                     120           1,950              70                                              80

[[Page 15404]]

 
                                                                     180           2,550             100                                             100
                                                                     240           3,090             110                                             120
--------------------------------------------------------------------------------------------------------------------------------------------------------

    ADOT also must abide by the terms and conditions of the December 
19, 2019 Biological Opinion and Incidental Take Statement issued by 
NMFS pursuant to section 7 of the Endangered Species Act.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has determined that the 
required mitigation measures provide the means effecting 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.

Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) 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 
project area. 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:
    <bullet> Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density).
    <bullet> 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 action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas).
    <bullet> Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors.
    <bullet> How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks.
    <bullet> Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat).
    <bullet> Mitigation and monitoring effectiveness.

Visual Monitoring

    Monitoring must be conducted by qualified, NMFS-approved PSOs, in 
accordance with the following:
    <bullet> PSOs must be independent (i.e., not construction 
personnel) and have no other assigned tasks during monitoring periods. 
At least one PSO must have prior experience performing the duties of a 
PSO during construction activity pursuant to a NMFS-issued IHA. Other 
PSOs may substitute other relevant experience, 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 IHA. Where a team of three or more PSOs is required, a 
lead observer or monitoring coordinator must be designated. The lead 
observer must have prior experience performing the duties of a PSO 
during construction activity pursuant to a NMFS-issued incidental take 
authorization. PSOs must be approved by NMFS prior to beginning any 
activity subject to this IHA; and
    <bullet> PSOs must record all observations of marine mammals as 
described in the Section 5 of the IHA and the Marine Mammal Monitoring 
Plan, 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:
    <bullet> Ability to conduct field observations and collect data 
according to assigned protocols;
    <bullet> Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
    <bullet> Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
    <bullet> Writing skills sufficient to prepare a report of 
observations 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
    <bullet> 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;
    Additionally, as required by NMFS' December 2019 Biological 
Opinion, each PSO will be trained and provided with reference materials 
to ensure standardized and accurate observations and data collection.
    ADOT must employ three PSOs during all pile driving and DTH. A 
minimum of one PSO (the lead PSO) must be assigned to the active pile 
driving or DTH location to monitor the shutdown zones and as much of 
the Level B harassment zones as possible. Two additional PSOs are also 
required, though the observation points may vary depending on the 
construction activity and location of the piles. To select the best 
observation locations, prior to start of construction, the lead PSO 
will stand at the construction site to monitor the Level A harassment 
zones while two or more PSOs travel in opposite directions from the 
project site along Tongass Narrows until they have reached the edge of 
the appropriate Level B harassment zone, where they will identify 
suitable observation points from which to observe. When needed, an 
additional PSO will be stationed on the north end of Revilla Island 
observing to the northwest. See Figure 2-11 of ADOT's Marine Mammal

[[Page 15405]]

Monitoring and Mitigation Plan for a map of planned PSO locations. If 
visibility deteriorates so that the entire width of Tongass Narrows at 
the harassment zone boundary is not visible, additional PSOs may be 
positioned so that the entire width is visible, or work will be halted 
until the entire width is visible to ensure that any humpback whales 
entering or within the harassment zone are detected by PSOs.
    When DTH use occurs, or simultaneous use of one DTH with a 
vibratory hammer or two DTH systems occurs, creating Level B harassment 
zones that exceed 13 km and 21 km, respectively, and Level A harassment 
zones that extend over 6 km, one additional PSO will be stationed at 
the northernmost land-based location at the entrance to Tongass Narrows 
(at least two PSOs total at that location, four PSOs on duty across all 
PSO locations). One of these PSO will focus on Tongass Narrows, 
specifically watching for marine mammals that could approach or enter 
Tongass Narrows and the project area. The second PSO will look out into 
Clarence Strait, watching for marine mammals that could swim through 
the ensonified area. No additional PSOs will be required at the 
southern-most monitoring location because the Level B harassment zones 
are truncated to the southeast by islands, which prevent propagation of 
sound in that direction beyond the confines of Tongass Narrows. Takes 
by Level B harassment will be recorded by PSOs and extrapolated based 
upon the number of observed takes and the percentage of the Level B 
harassment zone that was not visible.
    Each construction contractor managing an active construction site 
and on-going in-water pile installation or removal will provide 
qualified, independent PSOs for their specific contract. The ADOT 
environmental coordinator for the project will implement coordination 
between or among the PSO contractors. It will be a required component 
of their contracts that PSOs coordinate, collaborate, and otherwise 
work together to ensure compliance with project permits and 
authorizations.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities, or 60 days prior to a requested date of issuance of any 
future IHAs for projects at the same location, whichever comes first. 
The report will include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report must include:
    <bullet> Dates and times (begin and end) of all marine mammal 
monitoring;
    <bullet> 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, vibratory or DTH) and the 
total equipment duration for vibratory removal or DTH for each pile or 
hole or total number of strikes for each pile (impact driving);
    <bullet> PSO locations during marine mammal monitoring;
    <bullet> 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;
    <bullet> 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 (min/max/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; Description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses thought to have 
resulted from the activity (e.g., no response or changes in behavioral 
state such as ceasing feeding, changing direction, flushing, or 
breaching);
    <bullet> Number of marine mammals detected within the harassment 
zones and shutdown zones, by species;
    <bullet> Table summarizing any incidents resulting in take of ESA-
listed species;
    <bullet> Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensued, and resulting changes in behavior of the 
animal(s), if any;
    <bullet> Description of other human activity within each monitoring 
period;
    <bullet> Description of any deviation from initial proposal in pile 
numbers, pile types, average driving times, etc.;
    <bullet> Brief description of any impediments to obtaining reliable 
observations during construction period;
    <bullet> Description of any impediments to complying with these 
mitigation measures; and
    <bullet> If visibility degrades to where the PSO(s) cannot view the 
entire impact or vibratory harassment zones, take of humpback whales 
will be extrapolated based on the estimated percentage of the 
monitoring zone that remains visible and the number of marine mammals 
observed.
    If no comments are received from NMFS within 30 days, the draft 
final report will constitute the final report. 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 IHA-holder must 
immediately cease the specified activities and report the incident to 
the Office of Protected Resources (OPR) 
(<a href="/cdn-cgi/l/email-protection#79292b57302d2957341617100d160b10171e2b1c09160b0d0a3917161818571e160f"><span class="__cf_email__" data-cfemail="b3e3e19dfae7e39dfedcdddac7dcc1daddd4e1d6c3dcc1c7c0f3dddcd2d29dd4dcc5">[email protected]</span></a>), NMFS and to the Alaska Regional 
Stranding Coordinator as soon as feasible. If the death or injury was 
clearly caused by the specified activity, ADOT 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 IHA-
holder must not resume their activities until notified by NMFS. The 
report must include the following information:
    <bullet> Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    <bullet> Species identification (if known) or description of the 
animal(s) involved;
    <bullet> Condition of the animal(s) (including carcass condition if 
the animal is dead);
    <bullet> Observed behaviors of the animal(s), if alive;
    <bullet> If available, photographs or video footage of the 
animal(s); and
    <bullet> General circumstances under which the animal was 
discovered.

[[Page 15406]]

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., population-
level 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 responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), 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 environmental 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, our analysis applies to all species listed in 
Table 1 for which take could occur, given that NMFS expects the 
anticipated effects of the planned pile driving/removal and DTH on 
different marine mammal stocks to be similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, NMFS has identified species-specific factors to 
inform the analysis.
    Pile driving and DTH activities associated with the project, as 
outlined previously, have 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 and DTH. 
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.
    NMFS does not anticipate that serious injury or mortality will 
occur as a result of ADOT's planned activity given the nature of the 
activity, even in the absence of required mitigation. Further, no take 
by Level A harassment is anticipated for Pacific white-sided dolphin, 
killer whale, or humpback whale, due to the likelihood of occurrence 
and/or required mitigation measures. As stated in the mitigation 
section, ADOT will implement shutdown zones that equal or exceed many 
of the Level A harassment isopleths shown in Table 12. Take by Level A 
harassment is authorized for some species (Steller sea lions, harbor 
seals, harbor porpoises, Dall's porpoises, and minke whales) to account 
for the potential that an animal could enter and remain within the area 
between a Level A harassment zone and the shutdown zone for a duration 
long enough to be taken by Level A harassment, and in some cases, to 
account for the possibility that an animal could enter a shutdown zone 
without detection given the various obstructions along the shoreline, 
and remain in the Level A harassment zone for a duration long enough to 
be taken by Level A harassment before being observed and a shutdown 
occurring. Any take by Level A harassment is expected to arise from, at 
most, a small degree of PTS 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 PTS. 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 PTS or TTS potentially incurred here is not 
expected to adversely impact individual fitness, let alone annual rates 
of recruitment or survival.
    For all species and stocks, take will occur within a limited, 
confined area (adjacent to the project site) of the stock's range. Take 
by Level A harassment and Level B harassment will be reduced to the 
level of least practicable adverse impact through use of mitigation 
measures described herein. Further the amount of take authorized is 
small when compared to stock abundance.
    Behavioral responses of marine mammals to pile driving, pile 
removal, and DTH at the sites in Tongass Narrows are expected to be 
mild, short term, and temporary. 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 observable such as changes 
in vocalization patterns. Given that pile driving, pile removal, and 
DTH will occur for only a portion of the project's duration and often 
on nonconsecutive days, any harassment will be temporary. Additionally, 
many of the species present in Tongass Narrows or Clarence Strait 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.
    For all species except humpback whales, there are no known 
Biologically Important Areas (BIAs) near the project zone that will be 
impacted by ADOT's planned activities. For humpback whales, the whole 
of Southeast Alaska is a seasonal BIA from spring through late fall 
(Ferguson et al. 2015), however, Tongass Narrows and Clarence Strait 
are not important portions of this habitat due to development and human 
presence. Tongass Narrows is also a small passageway and represents a 
very small portion of the total available habitat. Also, while 
southeast Alaska is considered an important area for feeding humpback 
whales between March and May (Ellison et al. 2012), it is not currently 
designated as critical habitat for humpback whales (86 FR 21082; April 
21, 2021).
    More generally, there are no known calving or rookery grounds 
within the project area, but anecdotal evidence from local experts 
shows that marine mammals are more prevalent in Tongass Narrows and 
Clarence Strait during spring and summer associated with feeding on 
aggregations of fish, meaning the area may play a role in foraging. 
Because ADOT's activities could occur during any season, takes may 
occur during important feeding times. However, the project area 
represents a small portion of available foraging habitat and impacts on 
marine mammal feeding for all species, including humpback whales, 
should be minimal.
    Any impacts on marine mammal prey that occur during ADOT's planned 
activity will 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. Indirect effects on marine mammal prey 
during the construction are expected to be minor, and these

[[Page 15407]]

effects are unlikely to cause substantial effects on marine mammals at 
the individual level, with no expected effect on annual rates of 
recruitment or survival.
    In addition, it is unlikely that minor noise effects in a small, 
localized area of habitat will have any effect on the reproduction or 
survival of any individuals, much less the stocks' annual rates of 
recruitment or survival. In combination, we believe that these factors, 
as well as the available body of evidence from other similar 
activities, demonstrate that the potential effects of the specified 
activities will have only minor, short-term effects on individuals. The 
specified activities are not expected to impact rates of recruitment or 
survival and will, therefore, not result in population-level impacts.
    In summary, and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect the species or stock through 
effects on annual rates of recruitment or survival:
    <bullet> No serious injury or mortality is anticipated or 
authorized;
    <bullet> Take by Level A harassment of Pacific white-sided dolphin, 
killer whale, and humpback whale is not anticipated or authorized;
    <bullet> ADOT will implement mitigation measures including soft-
starts for impact pile driving and shutdown zones to minimize the 
numbers of marine mammals exposed to injurious levels of sound, and to 
ensure that any take by Level A harassment is, at most, a small degree 
of PTS;
    <bullet> The intensity of anticipated takes by Level B harassment 
is relatively low for all stocks and will not be of a duration or 
intensity expected to result in impacts on reproduction or survival;
    <bullet> The only known area of specific biological importance 
covers a broad area of southeast Alaska for humpback whales, and the 
project area is a very small portion of that BIA. No other known areas 
of particular biological importance to any of the affected species or 
stocks are impacted by the activity, including ESA-designated critical 
habitat;
    <bullet> The project area represents a very small portion of the 
available foraging area for all potentially impacted marine mammal 
species and stocks and anticipated habitat impacts are minor; and
    <bullet> Monitoring reports from similar work in Tongass Narrows 
have documented little to no effect on individuals of the same species 
impacted by the specified activities.
    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 finds that the total marine mammal take from 
the planned activity will have a negligible impact on all affected 
marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take 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 number of individuals 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 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.
    The instances of take NMFS authorized are below one third of the 
estimated stock abundance for all stocks (see Table 14). The number of 
animals that we expect to authorize to be taken from these stocks is 
considered small relative to the relevant stocks' abundances even if 
each estimated taking occurred to a new individual, which is an 
unlikely scenario. Some individuals may return multiple times in a day, 
but PSOs will count them as separate takes if they cannot be 
individually identified.
    The Alaska stock of Dall's porpoise has no official NMFS abundance 
estimate for this area, as the most recent estimate is greater than 
eight years old. The most recent estimate was 13,110 animals for just a 
portion of the stock's range. Therefore, the 227 authorized takes of 
this stock clearly represent small numbers of this stock.
    Likewise, the Southeast Alaska stock of harbor porpoise has no 
official NMFS abundance estimate as the most recent estimate is greater 
than 8 years old. The most recent estimate was 11,146 animals (Muto et 
al. 2021) and it is highly unlikely this number has drastically 
declined. Therefore, the 32 authorized takes of this stock clearly 
represent small numbers of this stock.
    There is no current or historical estimate of the Alaska minke 
whale stock, but there are known to be over 1,000 minke whales in the 
Gulf of Alaska (Muto et al. 2018), so the 3 authorized takes clearly 
represent small numbers of this stock. Additionally, the range of the 
Alaska stock of minke whales is extensive, stretching from the Canadian 
Pacific coast to the Chukchi Sea, and ADOT's project area impacts a 
small portion of this range.
    Based on the analysis contained herein of the planned activity 
(including the required mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS finds that small numbers of 
marine mammals will be taken relative to the population size of the 
affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    In order to issue an IHA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaska 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.
    Harbor seals are the marine mammal species most regularly harvested 
for subsistence by households in Ketchikan and Saxman (a community a 
few miles south of Ketchikan, on the Tongass Narrows). Eighty harbor 
seals were harvested by Ketchikan residents in 2007, which ranked 
fourth among all communities in Alaska that year for harvest of harbor 
seals. Thirteen harbor seals were harvested by Saxman residents in 
2007. In 2008, two Steller sea lions were harvested by Ketchikan-based 
subsistence hunters, but this is the only record of sea lion harvest by 
residents of either Ketchikan or Saxman. In 2012, the community of 
Ketchikan had an estimated subsistence take of 22 harbor seals and 0 
Steller sea lion (Wolf et al. 2013). NMFS is not aware of more recent 
data. Hunting usually occurs in October and November (ADF&G 2009), but 
there are also records of relatively high harvest in May (Wolfe et al. 
2013). The Alaska Department of Fish and

[[Page 15408]]

Game (ADF&G) has not recorded harvest of cetaceans from Ketchikan or 
Saxman (ADF&G 2018).
    All project activities will take place within the industrial area 
of Tongass Narrows immediately adjacent to Ketchikan where subsistence 
activities do not generally occur. Both the harbor seal and the Steller 
sea lion may be temporarily displaced from the project area. The 
project will also not have an adverse impact on the availability of 
marine mammals for subsistence use at locations farther away, where 
these construction activities are not expected to take place. Some 
minor, short-term harassment of the harbor seals could occur, but given 
the information above, we do not expect such harassment to have effects 
on subsistence hunting activities.
    Based on the description of the specified activity and the required 
mitigation and monitoring measures, NMFS has determined that there will 
not be an unmitigable adverse impact on subsistence uses from ADOT's 
planned activities.

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 (i.e., the issuance of an IHA) 
and alternatives with respect to potential impacts on the human 
environment. This action is consistent with categories of activities 
identified in Categorical Exclusion B4 of the Companion Manual for NAO 
216-6A, which do not individually or cumulatively have the potential 
for significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has determined 
that this action qualifies to be categorically excluded from further 
NEPA review.

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 issuance of IHAs, 
NMFS' Office of Protected Resources (OPR) consults internally whenever 
we propose to authorize take for endangered or threatened species, in 
this case with NMFS' Alaska Regional Office (AKRO).
    NMFS OPR is proposing to authorize take of the Central North 
Pacific stock of humpback whales, of which a portion belong to the 
Mexico DPS of humpback whales, which are ESA-listed. On February 6, 
2019, NMFS AKRO completed consultation with NMFS for the Tongass 
Narrows Project and issued a Biological Opinion. Reinitiation of formal 
consultation was required to analyze changes to the action that were 
not considered in the February 2019 opinion (PCTS# AKR-2018-9806/ECO# 
AKRO-2018-01287). The original opinion considered the effects of only 
one project component being constructed at a time and did not analyze 
potential effects of concurrent pile driving that may cause effects to 
the listed species that were not considered in the original opinion; 
therefore, reinitiation of formal consultation was required. NMFS' AKRO 
issued a revised Biological Opinion to NMFS' OPR on December 19, 2019 
that concluded that issuance of IHAs to ADOT is not likely to 
jeopardize the continued existence of Mexico DPS humpback whales. The 
effects of this Federal action were adequately analyzed in NMFS' 
Endangered Species Act (ESA) Section 7(a)(2) Biological Opinion for 
Construction of the Tongass Narrows Project (Gravina Access), revised 
December 19, 2019, which concluded that the take NMFS proposes to 
authorize through this IHA would not jeopardize the continued existence 
of any endangered or threatened species or destroy or adversely modify 
any designated critical habitat. NMFS has determined that issuance of 
this IHA does not require reinitiation of the December 2019 Biological 
Opinion.

Authorization

    NMFS has issued an IHA to ADOT for the potential harassment of 
small numbers of eight marine mammal species incidental to construction 
of four facilities in the channel between Gravina Island and 
Revillagigedo (Revilla) Island in Ketchikan, Alaska, that includes the 
previously explained mitigation, monitoring and reporting requirements.

    Dated: March 11, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2022-05561 Filed 3-17-22; 8:45 am]
BILLING CODE 3510-22-P


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