[Federal Register Volume 86, Number 21 (Wednesday, February 3, 2021)]
[Notices]
[Pages 7993-8003]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-02244]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XA815]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Naval Base San Diego Pier 6 
Replacement Project, San Diego, California

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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[[Page 7994]]

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 U.S. Navy (Navy) to incidentally harass, by Level B harassment 
only, marine mammals during activities associated with the Naval Base 
San Diego Pier 6 Replacement Project in San Diego, California.

DATES: This Authorization is effective from October 1, 2021 through 
September 30, 2022.

FOR FURTHER INFORMATION CONTACT: Dwayne Meadows, Ph.D., 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 
``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 July 14, 2020, NMFS received an application from the Navy 
requesting an IHA to take small numbers of California sea lions 
incidental to pile driving and removal associated with the Naval Base 
San Diego Pier 6 Replacement Project. The application was deemed 
adequate and complete on November 25, 2020. The Navy's request is for 
take of a small number of California sea lions by Level B harassment. 
Neither the Navy nor NMFS expects serious injury or mortality to result 
from this activity and, therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    The purpose of the project is to remove and replace a decaying and 
inadequate pier for Navy ships. Specifically, in-water construction 
work includes removing the existing pier (by vibratory pile extraction, 
water jetting, hydraulic underwater chainsaw, direct pulling, and/or 
pile clippers) consisting of a total of 1,998 12 to 24-inch piles, 
after removing above water structures and utilities. Once demolition 
has opened up space, construction will begin in the same location on a 
new pier measuring 37 meters (m) (120 feet (ft)) wide by 457 m (1,500 
ft) long. New construction work involves impact driving of 966 piles. 
This includes 528 24-inch structural concrete piles, 208 24-inch 
concrete fender piles, 4 20-inch piles for a load-out ramp, and 226 16-
inch fiberglass secondary and corner fender piles. Pile driving/removal 
is expected to take no more than 250 days. Pile driving would be by 
vibratory pile driving until resistance is too great and driving would 
switch to an impact hammer.
    A detailed description of the planned project is provided in the 
Federal Register notice for the proposed IHA (85 FR 80027; December 11, 
2020). 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 Response

    A notice of NMFS's proposal to issue an IHA to the Navy was 
published in the Federal Register on December 11, 2020 (85 FR 80027). 
That notice described, in detail, the Navy'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 received no public comment or comment letter from the 
Marine Mammal Commission.

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's 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's 
website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species with expected potential for occurrence in 
the project area in San Diego Bay 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 (2020). 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's 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's 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's U.S. Pacific SARs (e.g., Caretta et al., 2020).

[[Page 7995]]



                    Table 1--Species That Spatially Co-Occur With the Activity to the Degree That Take Is Reasonably Likely to Occur
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/MMPA status;    Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and sea lions):
--------------------------------------------------------------------------------------------------------------------------------------------------------
California Sea Lion.................  Zalophus californianus.  United States..........  -, -, N             257,606 (N/A, 233,515,     14,011       >321
                                                                                                             2014).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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 assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual Morality/Serious Injury (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.

    California sea lions (Zalophus californianus) spatially co-occur 
with the activity to the degree that take is reasonably likely to 
occur, and we are authorizing take of this species. Other marine mammal 
species observed in San Diego Bay are the coastal bottlenose dolphin 
(Tursiops truncatus), which is regularly seen in the North Bay; Pacific 
harbor seal (Phoca vitulina), which frequently enters the North Bay; 
and common dolphins (Delphinus spp.), which are rare visitors in the 
North Bay. Gray whales (Eschrichtius robustus) are occasionally sighted 
near the mouth of San Diego Bay during their winter migration (Naval 
Facilities Engineering Command, Southwest and Port of San Diego Bay, 
2013). Based on many years of observations and numerous Navy-funded 
surveys in San Diego Bay (Merkel and Associates, Inc., 2008; Sorensen 
and Swope, 2010; Graham and Saunders, 2014; Tierra Data Inc., 2016), 
these other marine mammals rarely occur south of the Coronado Bay 
Bridge, are not known to occur near Naval Base San Diego, and any 
occurrence in the project area would be very rare. Therefore, while 
coastal bottlenose dolphins, Pacific harbor seals, common dolphins, and 
gray whales have been reported in San Diego Bay, they are not 
anticipated to occur in the project area and no take of these species 
is anticipated or authorized.
    A detailed description of the of the species likely to be affected 
by the Navy'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 (85 FR 
80027; December 11, 2020); 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.

Potential Effects of Specified Activities on Marine Mammals and their 
Habitat

    The effects of underwater noise from the Navy's construction 
activities have the potential to result in behavioral harassment of 
marine mammals in the vicinity of the survey area. The notice of 
proposed IHA (85 FR 80027; December 11, 2020) included a discussion of 
the effects of anthropogenic noise on marine mammals and the potential 
effects of underwater noise from the Navy's construction activities on 
marine mammals and their habitat. That information and analysis is 
incorporated by reference into this final IHA determination and is not 
repeated here; please refer to the notice of proposed IHA (85 FR 80027; 
December 11, 2020).

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 would be by Level B harassment, as use of the 
acoustic source (i.e., vibratory or impact pile driving) has the 
potential to result in disruption of behavioral patterns for individual 
marine mammals. Based on the nature of the activity and the anticipated 
effectiveness of the mitigation measures (i.e., shutdown)--discussed in 
detail below in Mitigation section, Level A harassment is neither 
anticipated nor authorized.
    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 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). Due to the lack of 
marine mammal density, NMFS relied on local occurrence data and group 
size to estimate take. Below, we describe the factors considered here 
in more detail and present the take estimate.

[[Page 7996]]

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 Permanent Threshold Shift (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 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 decibel (dB) re 1 microPascal ([mu]Pa) (root 
mean square (rms)) for continuous (e.g., vibratory pile-driving) and 
above 160 dB re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., 
impact pile driving) or intermittent (e.g., scientific sonar) sources.
    The Navy's proposed activity includes the use of continuous 
(vibratory pile-driving, water jetting, chainsaw and pile clippers) and 
impulsive (impact pile-driving) sources, and therefore the 120 and 160 
dB re 1 [mu]Pa (rms) thresholds are applicable. However, as discussed 
above, the Navy has established that the ambient noise in the project 
area is 126 dB re 1 [mu]Pa (rms). Since this is louder than the 120 dB 
threshold for continuous sources, 126 dB becomes the effective 
threshold for Level B harassment for continuous sources.
    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). The Navy's activity includes the use of 
impulsive (impact pile-driving) and non-impulsive (vibratory pile 
driving/removal and other removal methods) sources.
    These thresholds are provided in Table 2. 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 2--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 proposed 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 removal, water jetting, pile clippers and underwater chainsaws).
    Vibratory hammers produce constant sound when operating, and 
produce vibrations that liquefy the sediment surrounding the pile, 
allowing it to penetrate to the required seating depth or be withdrawn 
more easily. An impact hammer is a steel device that works like a 
piston, producing a series of independent strikes to drive the pile. 
Impact hammering typically generates the loudest noise associated with 
pile installation. The actual durations of each installation method 
vary depending on the type and size of the pile.
    In order to calculate distances to the Level A harassment and Level 
B harassment sound thresholds for piles of various sizes 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 
(see Table 3). Data for the removal methods including water jetting, 
pile clippers and underwater chainsaws come from data gathered at other 
nearby Navy projects in San Diego Bay (NAVFAC SW, 2020), the source 
levels used are from the averages of the maximum source levels 
measured, a somewhat more conservative measure than the median sound 
levels we typically use.

[[Page 7997]]



                                      Table 3--Project Sound Source Levels
----------------------------------------------------------------------------------------------------------------
               Pile driving activity                   Estimated sound source level at
----------------------------------------------------    10 meters without attenuation
                                                    ------------------------------------  Data source and proxy
             Method                   Pile type        dB RMS      dB SEL      dB peak
----------------------------------------------------------------------------------------------------------------
Vibratory Extraction...........  12-inch timber/            152  ..........  ..........  Greenbusch Group
                                  plastic.                                                (2018).
                                 20 and 24-inch             160  ..........  ..........  Caltrans (2015), Table
                                  concrete.                                               I.2-2, 24-inch steel
                                                                                          sheet.
                                 16-inch steel.....         160  ..........  ..........  Caltrans (2015), Table
                                                                                          I.2-2, 24-inch steel
                                                                                          sheet.
Water Jetting..................  20-inch concrete..         158  ..........  ..........  NAVFAC SW (2020), 24 x
                                                                                          30-inch concrete.
Underwater Chainsaw............  12 to 24-inch              150  ..........  ..........  NAVFAC SW (2020), 16-
                                  concrete.                                               inch concrete.*
Small Pile Clipper.............  12-inch timber/            154  ..........  ..........  NAVFAC SW (2020), 13-
                                  plastic.                                                inch polycarbonate.
Large Pile Clipper.............  20-inch concrete..         161  ..........  ..........  NAVFAC SW (2020), 24-
                                                                                          inch concrete.
Impact Hammer..................  20 and 24-inch             176         166         188  Caltrans (2015), Table
                                  concrete.                                               I.2-1, 24-inch
                                                                                          concrete.
                                 16-inch fiberglass         153      ** 144      ** 177  Caltrans (2015), 13-
                                                                                          inch plastic.
----------------------------------------------------------------------------------------------------------------
Note: SEL = single strike sound exposure level; dB peak = peak sound level; rms = root mean square.
* Source level was 147 dB at 17m from source, back calculated to 150dB using transmission loss coefficient of
  15.
** Average of the peak values was 166 and that value was used in modelling in Dell'Osto and Dahl (2019) rather
  than the absolute peak we recommend for use in the user spreadsheet, SEL calculated from assumed strike rate
  in Dell'Osto and Dahl (2019).

    During pile driving installation activities, there may be times 
when two pile extraction methods (pile clippers, water jetting, 
underwater chainsaws or vibratory pile removal) are used 
simultaneously. The likelihood of such an occurrence is anticipated to 
be infrequent, will depend on the specific methods chosen by the 
contractor, and would be for short durations on that day. In-water pile 
removal occurs intermittently, and it is common for removal to start 
and stop multiple times as each pile is adjusted and its progress is 
measured. Moreover, the Navy has multiple options for pile removal 
depending on the pile type and condition, sediment, and how stuck the 
pile is, etc. When two continuous noise sources, such as pile clippers, 
have overlapping sound fields, there is potential for higher sound 
levels than for non-overlapping sources. When two or more pile removal 
methods (pile clippers, water jetting, underwater chainsaws or 
vibratory pile removal) are used simultaneously, and the sound field of 
one source encompasses the sound field of another source, the sources 
are considered additive and combined using the following rules (see 
Table 4): For addition of two simultaneous methods, the difference 
between the two sound source levels (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 dB, there is no addition (NMFS 
2018b; WSDOT 2018).

 Table 4--Rules for Combining Sound Levels Generated During Pile Removal
------------------------------------------------------------------------
      Difference in SSL           Level A zones         Level B zones
------------------------------------------------------------------------
0 or 1 dB...................  Add 3 dB to the       Add 3 dB to the
                               higher source level.  higher source
                                                     level.
2 or 3 dB...................  Add 2 dB to the       Add 2 dB to the
                               higher source level.  higher source
                                                     level.
4 to 9 dB...................  Add 1 dB to the       Add 1 dB to the
                               higher source level.  higher source
                                                     level.
10 dB or more...............  Add 0 dB to the       Add 0 dB to the
                               higher source level.  higher source
                                                     level.
------------------------------------------------------------------------
Source: Modified from USDOT 1995, WSDOT 2018, and NMFS 2018b.
Note: dB = decibels; SSL = sound source level.

    There is also the possibility that impact installation of piles 
could happen simultaneously with any of the non-impulsive removal 
methods over large portions of the project as described above. On days 
when this occurs the Level A harassment zones would be based on the 
zones calculated for impact pile driving while the Level B harassment 
zone would be the largest of the zones for whatever construction 
methods are being used that day.

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 would lie between spherical and 
cylindrical spreading loss conditions, which is the most appropriate 
assumption for the Navy's proposed activity in the absence of specific 
modelling. For this project however, the Navy did model sound 
propagation for the impact and vibratory hammering methods (Dall'Osto 
and Dahl 2019). For all other pile removal methods we used the 
practical spreading value.
    The Navy determined underwater noise would fall below the 
behavioral effects threshold of 126 dB rms for marine mammals at 
distances of less than 10 to 7,140 m depending on the pile type(s) and 
methods (Table 5). It should be noted that based on the bathymetry and 
geography of San Diego Bay, sound will not reach the full distance of 
the Level B harassment isopleths in all directions. Because the Navy's 
as yet unhired contractor has not

[[Page 7998]]

decided which of the various pile removal methods it will use, we only 
calculate a worst-case scenario of simultaneous operation of two of the 
loudest sound producing methods (large pile clippers) to consider the 
largest possible harassment zones for simultaneous pile removal.

                  Table 5--Level A and Level B Isopleths for Each Pile Driving Type and Method
----------------------------------------------------------------------------------------------------------------
                               Pile driving activity                                  Radial distance or maximum
------------------------------------------------------------------------------------  modeled length x width (m)
                                                                                    ----------------------------
                     Method                                   Pile type                Level A        Level B
----------------------------------------------------------------------------------------------------------------
Vibratory Extraction...........................  12-inch timber/plastic............         < 10     2167 x 1065
                                                 20 and 24-inch concrete...........         < 10   6,990 x 1,173
                                                 16-inch steel.....................         < 10   7,140 x 1,595
Water Jetting..................................  20-inch concrete..................         < 10            1359
Underwater Chainsaw............................  12 to 24-inch concrete............         < 10             398
Small Pile Clipper.............................  12-inch timber/plastic............         < 10             736
Large Pile Clipper.............................  20 to 24-inch concrete............         < 10            2154
Two Large Pile Clippers........................  20 to 24-inch concrete............         < 10            3415
Impact Hammer..................................  20 and 24-inch concrete...........         < 10             192
                                                 16-inch fiberglass................         < 10            < 10
----------------------------------------------------------------------------------------------------------------

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 take 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 
impact/vibratory pile driving or removal 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 would not incur PTS.
    As discussed above, the Navy modelled sound propagation for impact 
and vibratory hammering of piles (Dall'Osto and Dahl 2019) and used 
those models to calculate Level A harassment isopleths. For all other 
pile removal methods we used the User Spreadsheet to determine the 
Level A harassment isopleths. Inputs used in the User Spreadsheet or 
models are reported in Table 6 and the resulting isopleths are reported 
in Table 6 for each of construction methods.

Table 6--NMFS Technical Guidance User Spreadsheet Input to Calculate Level A Isopleths for a Combination of Pile
                                                     Driving
----------------------------------------------------------------------------------------------------------------
                        Pile driving activity                          Radial distance or maximum modeled length
---------------------------------------------------------------------                 x width (m)
                                                                     -------------------------------------------
                 Method                            Pile type                           Strikes per pile/duration
                                                                       Piles per day    to drive a single pile
----------------------------------------------------------------------------------------------------------------
Vibratory Extraction....................  12-inch timber/plastic....               8  10 min
                                          20 and 24-inch concrete...               8  10 min
                                          16-inch steel.............               8  10 min
Water Jetting...........................  20-inch concrete..........               8  20 min
Underwater Chainsaw.....................  12 to 24-inch concrete....               8  10 min
Small Pile Clipper......................  12-inch timber/plastic....               8  10 min
Large Pile Clipper......................  20-inch concrete..........               8  10 min
Impact Hammer...........................  20 and 24-inch concrete...               7  600 strikes
                                          16-inch fiberglass........               7  600 strikes
----------------------------------------------------------------------------------------------------------------

    The above input scenarios lead to PTS isopleth distances (Level A 
thresholds) of less than 10 m for all methods and piles (Table 5).

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. Here we describe how the information provided above is 
brought together to produce a quantitative take estimate.
    No California sea lion density information is available for south 
San Diego Bay. Potential exposures to impact and vibratory pile driving 
noise for each threshold for California sea lions were estimated using 
data collected during a 2010 survey as reported in Sorensen and Swope 
(2010). During this survey two separate sea lions were observed in the 
project area.
    The available survey data from Sorenson and Swope (2010) and other 
unpublished monitoring data from recent nearby projects on Naval Base 
San Diego suggests two California sea lions could be present each day 
in the project area. However given the limited data available and the 
more northerly location of this project relative to the

[[Page 7999]]

recent dry dock project (https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-floating-dry-dock-project-naval-base-san-diego) where we estimate two California sea lions per day, to 
be conservative, we have estimated four California sea lions could be 
present each day. As noted above, there are 250 days of in-water work 
for this project. Multiplication of the above estimate of animals per 
day (4) times the days of work (250) results in a Level B harassment 
take of 1000 California sea lions (Table 7). The Navy intends to avoid 
Level A harassment take by shutting down activities if a California sea 
lion approaches within 20 m of the project site, which encompasses all 
Level A harassment ensonification zones. Therefore, no take by Level A 
harassment is anticipated or authorized.

  Table 7--Authorized Amount of Taking, by Level A Harassment and Level B Harassment, by Species and Stock and
                                            Percent of Take by Stock
----------------------------------------------------------------------------------------------------------------
                                                                          Authorized take
                             Species                             --------------------------------   Percent of
                                                                      Level B         Level A          stock
----------------------------------------------------------------------------------------------------------------
California sea lion (Zalophus californianus) U.S. Stock.........           1,000               0             0.4
----------------------------------------------------------------------------------------------------------------

Mitigation

    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 (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, 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.
    The following mitigation measures are in the IHA:
    <bullet> For in-water heavy machinery work other than pile driving, 
if a marine mammal comes within 10 m, operations shall cease and 
vessels shall reduce speed to the minimum level required to maintain 
steerage and safe working conditions. This type of work could include 
the following activities: (1) Movement of the barge to the pile 
location; or (2) positioning of the pile on the substrate via a crane 
(i.e., stabbing the pile);
    <bullet> Conduct briefings between construction supervisors and 
crews and the marine mammal monitoring team prior to the start of all 
pile driving activity and when new personnel join the work, to explain 
responsibilities, communication procedures, marine mammal monitoring 
protocol, and operational procedures;
    <bullet> For those marine mammals for which Level B harassment take 
has not been requested, in-water pile installation/removal will shut 
down immediately if such species are observed within or entering the 
Level B harassment zone; and
    <bullet> If take 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.
    The following mitigation measures would apply to the Navy's in-
water construction activities.
    <bullet> Establishment of Shutdown Zones--The Navy will establish 
shutdown zones for all pile driving and removal activities. The purpose 
of a shutdown zone is generally to define an area within which shutdown 
of the activity would occur upon sighting of a marine mammal (or in 
anticipation of an animal entering the defined area). Shutdown zones 
typically vary based on the activity type and marine mammal hearing 
group (Table 4). In this case there is only one species affected and 
all level A harassment isopleths are less than 10 m radius. To be 
conservative, the Navy will establish a 20 m shutdown zone for all pile 
driving or removal activities.
    <bullet> The placement of Protected Species Observers (PSOs) during 
all pile driving and removal activities (described in detail in the 
Monitoring and Reporting section) will ensure that the entire shutdown 
zone is visible during pile installation. Should environmental 
conditions deteriorate such that marine mammals within the entire 
shutdown zone would not be visible (e.g., fog, heavy rain), pile 
driving and removal must be delayed until the PSO is confident marine 
mammals within the shutdown zone could be detected.
    <bullet> Monitoring for Level B Harassment--The Navy will monitor 
the Level A and B harassment zones. Monitoring zones provide utility 
for observing by establishing monitoring protocols for areas adjacent 
to the shutdown zones. Monitoring zones enable observers to be aware of 
and communicate the presence of marine mammals in the project area 
outside the shutdown zone and thus prepare for a potential halt of 
activity should the animal enter the shutdown zone. Placement of PSOs 
will allow PSOs to observe marine mammals within the Level B harassment 
zones.
    <bullet> Pre-activity Monitoring--Prior to the start of daily in-
water construction activity, or whenever a break in pile driving/
removal of 30 minutes or longer occurs, PSOs will observe the shutdown 
and monitoring zones for a period of 30 minutes. The shutdown zone will 
be considered cleared when a marine

[[Page 8000]]

mammal has not been observed within the zone for that 30-minute period. 
If a marine mammal is observed within the shutdown zone, a soft-start 
cannot proceed until the animal has left the zone or has not been 
observed for 15 minutes. When a marine mammal for which Level B 
harassment take is authorized is present in the Level B harassment 
zone, activities may begin and Level B harassment take will be 
recorded. If the entire Level B harassment zone is not visible at the 
start of construction, pile driving activities can begin. If work 
ceases for more than 30 minutes, the pre-activity monitoring of the 
shutdown zones will commence.
    <bullet> Soft Start--Soft-start procedures are believed to provide 
additional protection to marine mammals by providing warning and/or 
giving marine mammals a chance to leave the area prior to the impact 
hammer operating at full capacity. For impact pile driving, contractors 
will be required to provide an initial set of three strikes from the 
hammer at reduced energy, followed by a 30-second waiting period. This 
procedure will be conducted three times before impact pile driving 
begins. Soft start will 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.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has determined that the 
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 
action 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); and
    <bullet> Mitigation and monitoring effectiveness.

Visual Monitoring

    Marine mammal monitoring must be conducted in accordance with the 
Monitoring Plan and section 5 of the IHA. Marine mammal monitoring 
during pile driving and removal must be conducted by NMFS-approved PSOs 
in a manner consistent with the following:
    <bullet> Independent PSOs (i.e., not construction personnel) who 
have no other assigned tasks during monitoring periods must be used;
    <bullet> At least one PSO must have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
incidental take authorization.
    <bullet> Other PSOs may substitute education (degree in biological 
science or related field) or training for experience;
    <bullet> Where a team of three or more PSOs are 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; and
    <bullet> The Navy must submit PSO Curriculum Vitae for approval by 
NMFS prior to the onset of pile driving.
    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.
    Up to four PSOs will be employed. PSO locations will provide an 
unobstructed view of all water within the shutdown zone, and as much of 
the Level A and Level B harassment zones as possible. PSO locations are 
as follows:
    (1) At the pile driving/removal site or best vantage point 
practicable to monitor the shutdown zones;
    (2) For activities with Level B harassment zones larger than 400 m 
two additional PSO locations will be used. One will be across from the 
project location along Inchon Road at Naval Amphibious Base Coronado; 
and
    (3) Two additional PSOs will be located in a small boat. The boat 
will conduct a pre-activity survey of the entire monitoring area prior 
to in-water construction. The boat will start from south of the project 
area (where potential marine mammal occurrence is lowest) and proceed 
to the north. When the boat arrives near the northern boundary of the 
Level B harassment zone (e.g., just north of the western side of the 
Coronado Bridge as depicted in the Figures in the monitoring plan) it 
will set up station so the PSOs are best situated to detect any marine 
mammals that may approach from the north. The two PSOs aboard will 
split monitoring duties in order to monitor a 360 degree sweep around 
the vessel with each PSO responsible for 180 degrees of observable 
area.

[[Page 8001]]

    Monitoring will be conducted 30 minutes before, during, and 30 
minutes after pile driving/removal activities. In addition, observers 
shall record all incidents of marine mammal occurrence, regardless of 
distance from activity, and shall document any behavioral reactions in 
concert with distance from piles being driven or removed. Pile driving 
activities include the time to install or remove a single pile or 
series of piles, as long as the time elapsed between uses of the pile 
driving or drilling equipment is no more than 30 minutes.

Hydroacoustic Monitoring and Reporting

    The Navy has volunteered to conduct hydroacoustic monitoring of all 
pile driving and removal methods. Data will be collected for a 
representative number of piles (three to five) for each installation or 
removal method. As part of the below-mentioned report, or in a separate 
report with the same timelines as above, the Navy will provide an 
acoustic monitoring report for this work. Hydroacoustic monitoring 
results can be used to adjust the size of the Level B harassment and 
monitoring zones after a request is made and approved by NMFS. The 
acoustic monitoring report must, at minimum, include the following:
    <bullet> Hydrophone equipment and methods: recording device, 
sampling rate, distance (m) from the pile where recordings were made; 
depth of recording device(s);
    <bullet> Type of pile being driven or removed, substrate type, 
method of driving or removal during recordings;
    <bullet> For impact pile driving: Pulse duration and mean, median, 
and maximum sound levels (dB re: 1[micro]Pa): SELcum, peak sound 
pressure level (SPLpeak), and single-strike sound exposure level (SELs-
s);
    <bullet> For vibratory removal and other non-impulsive sources: 
Mean, median, and maximum sound levels (dB re: 1[micro]Pa): Root mean 
square sound pressure level (SPLrms), SELcum; and
    <bullet> Number of strikes (impact) or duration (vibratory or other 
non-impulsive sources) per pile measured, one-third octave band 
spectrum and power spectral density plot.

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 how many and what type of piles were 
driven or removed and by what method (i.e., impact or vibratory and if 
other removal methods were used);
    <bullet> Weather parameters and water conditions during each 
monitoring period (e.g., wind speed, percent cover, visibility, sea 
state);
    <bullet> The number of marine mammals observed, by species, 
relative to the pile location and if pile driving or removal was 
occurring at time of sighting;
    <bullet> Age and sex class, if possible, of all marine mammals 
observed;
    <bullet> PSO locations during marine mammal monitoring;
    <bullet> Distances and bearings of each marine mammal observed to 
the pile being driven or removed for each sighting (if pile driving or 
removal was occurring at time of sighting);
    <bullet> Description of any marine mammal behavior patterns during 
observation, including direction of travel and estimated time spent 
within the Level A and Level B harassment zones while the source was 
active;
    <bullet> Number of individuals of each species (differentiated by 
month as appropriate) detected within the monitoring zone;
    <bullet> Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensued, and resulting behavior of the animal, if 
any; and
    <bullet> Description of attempts to distinguish between the number 
of individual animals taken and the number of incidences of take, such 
as ability to track groups or individuals.
    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 Navy shall report the 
incident to the Office of Protected Resources (OPR), NMFS and to the 
regional stranding coordinator as soon as feasible. If the death or 
injury was clearly caused by the specified activity, the Navy 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.

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's 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

[[Page 8002]]

sources of human-caused mortality, or ambient noise levels).
    Pile driving activities have the potential to disturb or displace 
marine mammals. Specifically, the project activities may result in 
take, in the form of Level B harassment from underwater sounds 
generated from pile driving and removal. Potential takes could occur if 
individuals are present in the ensonified zone when these activities 
are underway.
    The takes from Level B harassment would be due to potential 
behavioral disturbance, TTS, and PTS. No mortality is anticipated given 
the nature of the activity and measures designed to minimize the 
possibility of injury to marine mammals. The potential for harassment 
is minimized through the construction method and the implementation of 
the planned mitigation measures (see Mitigation section).
    The nature of the pile driving project precludes the likelihood of 
serious injury or mortality. Take would occur within a limited, 
confined area (south-central San Diego Bay) of the stock's range. 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 extremely small when compared to stock 
abundance.
    Behavioral responses of marine mammals to pile driving at the 
project site, if any, are expected to be mild and temporary. Marine 
mammals within the Level B harassment zone may not show any visual cues 
they are disturbed by activities (as noted during modification to the 
Kodiak Ferry Dock (see 80 FR 60636, October 7, 2015) or 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 
the short duration of noise-generating activities per day and that pile 
driving and removal would occur across six months, any harassment would 
be temporary. There are no other areas or times of known biological 
importance for any of the affected species.
    In addition, it is unlikely that minor noise effects in a small, 
localized area of habitat would have any effect on the stocks' ability 
to recover. 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 mortality or Level A harassment is anticipated or 
authorized;
    <bullet> No important habitat areas have been identified within the 
project area;
    <bullet> For all species, San Diego Bay is a very small and 
peripheral part of their range;
    <bullet> The Navy would implement mitigation measures such as 
vibratory driving piles to the maximum extent practicable, soft-starts, 
and shut downs; and
    <bullet> Monitoring reports from similar work in San Diego Bay 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 monitoring and mitigation 
measures, NMFS finds that the total marine mammal take from the 
proposed 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 section 101(a)(5)(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 amount of take NMFS authorizes is below one third of the 
estimated stock abundance of California sea lions (in fact, take of 
individuals is less than 1% of the abundance of the affected stock). 
This is likely a conservative estimate because they assume all takes 
are of different individual animals which is likely not the case. Some 
individuals may return multiple times in a day, but PSOs would count 
them as separate takes if they cannot be individually identified.
    Based on the analysis contained herein of the proposed activity 
(including the 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

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

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 review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment. This action 
is consistent with categories of activities identified in Categorical 
Exclusion B4 (IHAs with no anticipated serious injury or mortality) of 
the Companion Manual for NOAA Administrative Order 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 the 
issuance of the IHA qualifies to be categorically excluded from further 
NEPA review.

Endangered Species Act

    Section 7(a)(2) of the 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 consults internally, in this 
case with the West Coast Region Protected Resources Division Office, 
whenever we propose to authorize take for endangered or threatened 
species.

[[Page 8003]]

    No incidental take of ESA-listed species is authorized or expected 
to result from this activity. Therefore, NMFS has determined that 
formal consultation under section 7 of the ESA is not required for this 
action.

Authorization

    NMFS has issued an IHA to the Navy for the potential harassment of 
small numbers of one marine mammal species incidental to the Naval Base 
San Diego Pier 6 Replacement project in San Diego, CA, provided the 
previously mentioned mitigation, monitoring and reporting requirements 
are followed.

    Dated: January 27, 2021.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2021-02244 Filed 2-2-21; 8:45 am]
BILLING CODE 3510-22-P