Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Construction Activities Associated With the Murray St. Bridge Seismic Retrofit Project in Santa Cruz, California, 27452-27462 [2023-09193]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 88, Number 84 (Tuesday, May 2, 2023)]
[Notices]
[Pages 27452-27462]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-09193]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC897]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Construction Activities Associated 
With the Murray St. Bridge Seismic Retrofit Project in Santa Cruz, 
California

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

ACTION: Notice; issuance of incidental harassment authorizations.

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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 two consecutive incidental harassment 
authorizations (IHAs) to the City of Santa Cruz to incidentally harass 
marine mammals during construction activities associated with the 
seismic retrofit of the Murray St. Bridge in Santa Cruz, California.

DATES: These authorizations are effective from May 1, 2023 through 
April 30, 2024 and May 1, 2024 through April 30, 2025.

FOR FURTHER INFORMATION CONTACT: Jessica Taylor, 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/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. 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 proposed or, if the taking is limited to harassment, a notice of a 
proposed IHA is 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 April 19, 2022, NMFS received a request from the City of Santa 
Cruz (the City) for two consecutive 1-year IHAs to take marine mammals 
incidental to construction activities associated with the Murray St. 
Bridge seismic retrofit project in Santa Cruz, CA. Following NMFS' 
review of the application, the City submitted revised versions on 
August 25, 2022, October 25, 2022, and December 13, 2022, and a final 
revised version on January 12, 2023. The application was deemed 
adequate and complete on January 24, 2023. The

[[Page 27453]]

City's request is for take of small numbers of California sea lions 
(Zalophus californianus) and harbor seals (Phoca vitulina richardii) by 
Level B harassment and take of small numbers of harbor seals by Level A 
harassment. Neither the City nor NMFS expect serious injury or 
mortality to result from this activity and, therefore, IHAs are 
appropriate. There are no changes from the proposed IHA to the final 
IHA.

Description of Activity

 Overview

    The City plans to conduct a seismic retrofit on the Murray St. 
Bridge, which spans the Santa Cruz Small Craft Harbor. As part of the 
project, the City will use vibratory pile extraction to temporarily 
remove docks and associated piles to accommodate construction access to 
the bridge. Impact pile driving will be used to install additional 
bridge support piles. In order to facilitate installation of bridge 
piles, vibratory extraction may be used to construct a temporary 
trestle. As an alternative to the trestle, a temporary barge may be 
constructed instead. The purpose of the project is to provide the 
bridge with additional vertical support and resistance to lateral 
seismic forces by installing additional pilings and structural support 
elements.
    The City's activity includes impact and vibratory pile driving and 
vibratory pile removal, which may result in the incidental take of 
marine mammals by Level A and Level B harassment. The Murray St. Bridge 
project area includes waters within the Santa Cruz Small Craft Harbor 
and adjacent lands managed by the Santa Cruz Port District. 
Construction activities will span the course of 2 years, with the first 
year beginning on July 1, 2023 and lasting through July 31, 2023. The 
second year of construction activities will begin on July 1, 2024 and 
last through September 15, 2024. The City has requested an IHA for each 
of the 2 project years. However, given the City has applied for 
authorization for both project years concurrently and projects use 
similar activities, NMFS is issuing this single Federal Register notice 
announce the issuance of the two similar, but separate, IHAs.
    A detailed description of the planned construction project is 
provided in the Federal Register notice for the proposed IHAs (88 FR 
12316, February 27, 2023). Since that time, no changes have been made 
to the planned construction activities. Therefore, a detailed 
description is not provided here. Please refer to the Federal Register 
notice for the description of the specific activity. Mitigation, 
monitoring, and reporting measures are described in detail later in 
this document (please see Mitigation and Monitoring and Reporting).

Comments and Responses

    A notice of NMFS' proposal to issue two consecutive IHAs to the 
City was published in the Federal Register on February 27, 2023 (88 FR 
12316). That notice described, in detail, the City's activities, the 
marine mammal species that may be affected by the activities, and the 
anticipated effects on marine mammals. In that notice, we requested 
public input on the request for authorization described therein, our 
analyses, the proposed authorizations, and any other aspect of the 
notice of proposed IHAs, and requested that interested persons submit 
relevant information, suggestions, and comments. This proposed notice 
was available for a 30-day public comment period. During the 30-day 
public comment period, NMFS received no 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. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, incorporated here by reference, instead of 
reprinting the information. Additional information regarding population 
trends and threats may be found in NMFS' Stock Assessment Reports 
(SARs; 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 authorized 
for this 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. 
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 serious 
injury or mortality is expected to occur, PBR and annual serious injury 
and mortality from anthropogenic sources are included here as gross 
indicators of the status of the species or stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All stocks managed under the MMPA in this region 
are assessed in NMFS' U.S. Pacific SARs. All values presented in Table 
1 are the most recent available at the time of publication, including 
from the draft 2022 SARs, and are available online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                     Table 1--Marine Mammal Species \4\ Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         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--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    California sea lion.............  Zalophus californianus.  U.S....................  -, -, N             257,606 (N/A,233,515,      14,011       >320
                                                                                                             2014).
Family Phocidae (earless seals)

[[Page 27454]]

 
    Harbor seal.....................  Phoca vitulina.........  California.............  -, -, N             30,968 (N/A, 27,348,        1,641         43
                                                                                                             2012).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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 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.
\4\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
  (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).

    As indicated above, the two species (with two managed stocks) in 
Table 1 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. While bottlenose 
dolphins (Tursiops truncatus) and harbor porpoises (Phocoena phocoena) 
have been reported in the area, the temporal and/or spatial occurrence 
of these species is such that take is not expected to occur, and they 
are not discussed further beyond the explanation provided here. 
Bottlenose dolphins and harbor porpoises may transit nearshore areas 
just outside the mouth of the Harbor (Carretta et al., 2022). However, 
these species were not detected during any surveys of the Harbor area 
and are expected to remain outside the Harbor and beyond the project 
area.
    In addition, the southern sea otter (Enhydra lutris nereis) may be 
found in the Harbor. However, sea otters are managed by the U.S. Fish 
and Wildlife Service and are not considered further in this document.
    A detailed description of the species likely to be affected by the 
construction 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 of the proposed IHAs (88 FR 
12316, February 27, 2023); 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. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) 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.

                  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,

[[Page 27455]]

please see NMFS (2018) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from the City's construction 
activities have the potential to result in behavioral harassment of 
marine mammals in the vicinity of the project area. The notice of the 
proposed IHAs (88 FR 12316, February 27, 2023) included a discussion of 
the effects of anthropogenic noise on marine mammals and the potential 
effects of underwater noise from the City'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 the proposed IHAs (88 FR 
12316, February 27, 2023).

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized through these IHAs, which will inform both NMFS' 
consideration of ``small numbers,'' and the negligible impact 
determinations.
    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 source (i.e., impact pile driving) has the potential to 
result in disruption of behavioral patterns for individual marine 
mammals. There is also some potential for auditory injury (Level A 
harassment) to result, primarily for phocids because predicted auditory 
injury zones are larger than for otariids. Auditory injury is unlikely 
to occur for otariids. The mitigation and monitoring measures are 
expected to minimize the severity of the taking to the extent 
practicable.
    As described previously, no serious injury or mortality is 
anticipated or authorized for this activity. Below we describe how the 
authorized take numbers are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the authorized take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably 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--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021; Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile-
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g., 
scientific sonar) sources. Generally speaking, Level B harassment take 
estimates based on these behavioral harassment thresholds are expected 
to include any likely takes by temporary threshold shift (TTS) as, in 
most cases, the likelihood of TTS occurs at distances from the source 
less than those at which behavioral harassment is likely. TTS of a 
sufficient degree can manifest as behavioral harassment, as reduced 
hearing sensitivity and the potential reduced opportunities to detect 
important signals (conspecific communication, predators, prey) may 
result in changes in behavior patterns that would not otherwise occur.
    The City's planned construction activity includes the use of 
continuous (vibratory pile driving and removal) and impulsive (impact 
pile driving) sources, and therefore the RMS SPL thresholds of 120 and 
160 dB re 1 [mu]Pa are applicable.
    Level A harassment--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 City's 
planned activity includes the use of impulsive (impact hammer) and non-
impulsive (vibratory hammer) sources.
    These thresholds are provided in the table 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: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

[[Page 27456]]



                                         Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                            PTS onset thresholds * (received level)
            Hearing group             ------------------------------------------------------------------------------------------------------------------
                                                                     Impulsive                                               Non-impulsive
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans.........  Cell 1: L0-pk,flat: 219 dB; LE, LF,24h: 183 dB.......................  Cell 2: LE,, LF,24h: 199 dB.
Mid-Frequency (MF) Cetaceans.........  Cell 3: L0-pk,flat: 230 dB; LE, MF,24h: 185 dB.......................  Cell 4: LE,, MF,24h: 198 dB.
High-Frequency (HF) Cetaceans........  Cell 5: L0-pk,flat: 202 dB; LE,,HF,24h: 155 dB.......................  Cell 6: LE, HF,24h: 173 dB.
Phocid Pinnipeds (PW) (Underwater)...  Cell 7: L0-pk,flat: 218 dB; LE,,PW,24h: 185 dB.......................  Cell 8: LE,PW,24h: 201 dB.
Otariid Pinnipeds (OW) (Underwater)..  Cell 9: L0-pk,flat: 232 dB; LE,,OW,24h: 203 dB.......................  Cell 10: LE,OW,24h: 219 dB.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Dual metric 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 are recommended for consideration.
Note: Peak sound pressure level (L0-pk) has a reference value of 1 [mu]Pa, and weighted cumulative sound exposure level (LE,) has a reference value of
  1[mu]Pa\2\s. In this Table, thresholds are abbreviated to be more reflective of International Organization for Standardization standards (ISO, 2017).
  The subscript ``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized hearing range of
  marine mammals (i.e., 7 Hz to 160 kHz). 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
  weighted 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 thresholds will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the project. Marine 
mammals are expected to be affected by sound generated by the primary 
components of the project (i.e., impact and vibratory pile driving).
    In order to calculate distances to the Level A harassment and Level 
B harassment thresholds for the methods and piles being used in this 
project, the City used acoustic monitoring data from various similar 
locations to develop source levels for the different pile types, sizes, 
and methods planned for use (Table 4).

                                         Table 4--Source Levels for Planned Removal and Installation Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                       Peak       Mean
                                                                                                      sound     maximum    SEL \1\
             Activity                    Location           Pile size/type            Method         pressure   RMS SPL    (dB re 1         Source
                                                                                                     (dB re 1   (dB re 1   [mu]Pa2
                                                                                                     [mu]Pa)    [mu]Pa)      sec)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Removal of existing bridge piles.  Bridge Bent 6. Dock   14'' P/C concrete...  Vibratory..........        171        163        155  NAVFAC SW, 2022.
 Removal of dock FF&T piles.        FF & BY.
Install new permanent bridge       Bridge Bents 4        30'' steel in CISS..  Impact.............        210        190        177  Caltrans, 2015.
 piles.                             through 8.
Install new permanent bridge       Bridge Bents 4        30'' steel in CISS..  Vibratory..........        196        159        175  Caltrans, 2020.
 piles.                             through 8.
Install new permanent bridge       Dock FF&T piles.....  14'' P/C concrete...  Impact.............        185        170        160  Caltrans, 2020.
 piles.
Install new permanent bridge       Dock FF&T piles.....  14'' P/C concrete...  Vibratory..........        171        163        155  NAVFAC SW, 2022.
 piles.
Install temporary trestle piles..  Adjacent to bridge..  20'' steel \2\......  Vibratory..........        194        154         NA  Caltrans, 2015.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Sound exposure level (SEL).
\2\ 24'' steel pipe used as a proxy for 20'' steel pile for vibratory pile driving.

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 City's activities. The City assumed an open water 
attenuation rate of 4.5 dB per doubling of distance. The Level B 
harassment zones and ensonified area for the City's activities are 
shown in Table 5.

[[Page 27457]]



           Table 5--Distances to Level B Harassment Thresholds
------------------------------------------------------------------------
                                                      Projected radial
                                                     distance to Level B
       Pile type/size                Method         harassment threshold
                                                             (m)
------------------------------------------------------------------------
                                 Year 1
------------------------------------------------------------------------
14'' P/C concrete...........  Vibratory...........                 7,356
------------------------------------------------------------------------
                                 Year 2
------------------------------------------------------------------------
30'' steel pipe pile in CISS  Impact..............                 1,000
                              Vibratory...........                 3,981
14'' p/c concrete...........  Impact..............                    46
                              Vibratory...........                 7,356
20'' steel pipe piles.......  Vibratory...........                 1,848
------------------------------------------------------------------------

Level A Harassment Zones

    The ensonified area associated with Level A harassment is more 
technically challenging to predict due to the need to account for a 
duration component. Therefore, NMFS developed an optional User 
Spreadsheet tool to accompany the Technical Guidance that can be used 
to relatively simply predict an isopleth distance for use in 
conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. For 
stationary sources, such as pile installation or removal, the optional 
User Spreadsheet tool predicts the distance at which, if a marine 
mammal remained at that distance for the duration of the activity, it 
would be expected to incur PTS. The isopleths generated by the User 
Spreadsheet used the same TL coefficient as the Level B harassment zone 
calculations (i.e., the practical spreading value of 15). Inputs in the 
User Spreadsheet tool (i.e., number of piles per day, duration, and/or 
strikes per pile) are presented in Table 1 of the Federal Register 
notice announcing the proposed IHAs (88 FR 12316, February 27, 2023). 
The maximum RMS SPL/SEL SPL for each pile type are presented in Table 
4. Resulting Level A harassment isopleths are reported below in Table 
6.

                               Table 6--Distances to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                                                  Projected distances to Level A
                                                                                     harassment threshold (m)
               Pile type/size                               Method               -------------------------------
                                                                                      Phocids        Otariids
----------------------------------------------------------------------------------------------------------------
                                                     Year 1
----------------------------------------------------------------------------------------------------------------
14'' P/C concrete..........................  Vibratory..........................            22.6             1.6
----------------------------------------------------------------------------------------------------------------
                                                     Year 2
----------------------------------------------------------------------------------------------------------------
30'' steel pipe pile in CISS...............  Impact.............................             300              22
                                             Vibratory..........................            12.3               1
14'' p/c concrete..........................  Impact.............................              13               1
                                             Vibratory..........................            22.6             1.6
20'' steel pipe piles......................  Vibratory..........................             5.7             0.4
----------------------------------------------------------------------------------------------------------------

Marine Mammal Occurrence

    In this section, we provide information about the occurrence of 
marine mammals, including density or other relevant information that 
will inform the take calculations. Unless otherwise specified, the term 
``pile driving'' in this section, and all following sections, may refer 
to either pile installation or removal. NMFS has carefully reviewed the 
City's analysis and concludes that it represents an appropriate and 
accurate method for estimating incidental take that may be caused by 
the City's activities.
    Daily occurrence estimates of marine mammals in the project area 
are based upon marine mammal surveys conducted in the vicinity of the 
Murray St. Bridge by EcoSystems West Consulting Group. Survey sessions 
were conducted in December 2006, September 2009 through October 2009. 
Of these monitoring years, the maximum counts of California sea lions 
and harbor seals were observed in 2009 (Table 7). As the 2009 surveys 
occurred during the fall season and the project will occur during the 
summer and fall seasons, the 2009 data are likely representative of 
maximum occurrences that could be expected in the project area.

[[Page 27458]]



Table 7--Maximum Counts of Species Likely Impacted by Planned Activities
------------------------------------------------------------------------
              Species                2006 Monitoring    2009 Monitoring
------------------------------------------------------------------------
California sea lion...............                  1                 15
Harbor seal.......................                  6                 11
------------------------------------------------------------------------

Take Estimation

    Here, we describe how the information provided above is synthesized 
to produce a quantitative estimate of the take that is reasonably 
likely to occur and authorized.
    Maximum occurrence estimates (reported in Table 7) were multiplied 
by the number of days of pile removal and installation (14 days in Year 
1; 98 days in Year 2) to calculate estimated take by Level B harassment 
of California sea lions and harbor seals (Table 8). The City assumed a 
maximum of two harbor seals will be present in the project area that 
may be impacted during the 37 days of impact pile driving. The expected 
occurrence of two harbor seals was multiplied by the number of impact 
pile driving days (37) to estimate take by Level A harassment of harbor 
seals. Given the very small Level A harassment isopleths for California 
sea lions and mitigation measures, Level A harassment of California sea 
lions is not expected nor authorized. By using the sighting-based 
approach, take values are not affected by the estimated harassment 
distances from Tables 6 and 7. NMFS has carefully reviewed these 
methods and agrees with this approach.

                           Table 8--Estimated Take by Level A and Level B Harassment and Percent of Stock Authorized for Take
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Maximum number                                                                       Percent of
                                                         of animals     Maximum total     Authorized    Authorized take       Total            stock
                       Species                           expected to     days of in-     take by Level     by Level B    authorized take  authorized for
                                                          occur/day     water work \1\   A harassment      harassment                          take
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Year 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Seal..........................................              11               14               0              154              154            0.49
California Sea Lion..................................              15               14               0              210              210           0.082
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Year 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Seal..........................................              11               98          \2\ 74            1,078            1,152            3.72
California Sea Lion..................................              15               98               0            1,470            1,470            0.57
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Includes potential temporary trestle installation/removal.
\2\ Assumes a maximum of 2 harbor seals sighted per day that may be impacted and 37 days of impact pile driving.

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, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost and impact on 
operations.

Shutdown Zones

    Prior to commencement of in-water construction activities, the City 
will establish shutdown zones for all activities. The purpose of a 
shutdown zone is to define an area within which shutdown of the 
activity will occur upon sighting of a marine mammal (or in 
anticipation of an animal entering the defined area). During all in-
water construction activities, the City will implement a standard 
minimum 10 m (32.8 ft) shutdown zone. If a marine mammal enters the 
shutdown zone, in-water activities must be stopped until visual 
confirmation that the animal has left the zone of the animal is not 
sighted for 15 minutes.
    All marine mammals will be monitored in the Level B harassment 
zones and throughout the area as far as visual monitoring can take 
place. If a marine mammal enters the Level B harassment zone, in-water 
activities will continue and the animal's presence within the estimated 
harassment zone must be documented. 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.

[[Page 27459]]



                              Table 9--Shutdown Zones and Level B Harassment Zones
----------------------------------------------------------------------------------------------------------------
                                                                     Minimum shutdown zone (m)        Level B
                   Pile size, type, and method                   --------------------------------   harassment
                                                                      Phocid          Otariid        zone (m)
----------------------------------------------------------------------------------------------------------------
                                                     Year 1
----------------------------------------------------------------------------------------------------------------
14'' p/c concrete vibratory removal.............................              10              10           7,356
----------------------------------------------------------------------------------------------------------------
                                                     Year 2
----------------------------------------------------------------------------------------------------------------
14'' p/c concrete vibratory install/removal.....................              10              10           7,356
----------------------------------------------------------------------------------------------------------------
14'' p/c concrete impact install................................                                              46
30'' steel pile in CISS impact install..........................                                           1,000
30'' steel pile in CISS vibratory install.......................                                           3,981
20'' steel pile vibratory install...............................                                           1,848
----------------------------------------------------------------------------------------------------------------

Protected Species Observers

    The placement of protected species observers (PSOs) during all pile 
driving activities (described in the Monitoring and Reporting section) 
will ensure that the entire shutdown zone is visible. Should 
environmental conditions deteriorate such that the entire shutdown zone 
would not be visible (i.e., fog, heavy rain), pile driving will be 
delayed until the PSO is confident marine mammals within the shutdown 
zone could be detected.

Pre-Activity Monitoring

    Prior to the start of daily in-water construction activity, or 
whenever a break in pile driving of 30 minutes or longer occurs, PSOs 
will observe the shutdown zone and monitoring zones for a period of 30 
minutes. The shutdown zone will be considered cleared when a marine 
mammal has not been observed within the zone for that 30-minute period. 
If a marine mammal is observed within the shutdown zones listed in 
Table 9, pile driving activity will be delayed or halted. If work 
ceases for more than 30 minutes, the pre-activity monitoring of the 
shutdown zones will commence. A determination that the shutdown zone is 
clear must be made during a period of good visibility (i.e., the entire 
shutdown zone and surrounding waters must be visible to the naked eye).
    Pre-construction monitoring will also take place over the course of 
at least 5 days before commencing in-water construction activities. The 
purpose of this monitoring effort will be to update occurrence 
information on marine mammals in the project area. Specifically, this 
monitoring will cover a period of at least 1 week for 4 hours each day.

Soft-Start Procedures

    Soft-start procedures provide additional protection to marine 
mammals by providing warning and/or giving marine mammals a chance to 
leave the area prior to the 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, then two subsequent reduced-energy strike 
sets. 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 City's mitigation measures, NMFS has 
determined that these mitigation measures provide the means of 
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 while 
conducting the activities. Effective reporting is critical to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Visual Monitoring

    Marine mammal monitoring during pile driving activities will be 
conducted by PSOs meeting the following NMFS requirements:
     Independent PSOs (i.e., not construction personnel) who 
have no other assigned tasks during monitoring periods will be used;
     At least one PSO will have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
incidental take authorization;

[[Page 27460]]

     Other PSOs may substitute education (degree in biological 
science or related field) or training for experience; and
     Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator will be designated. The lead 
observer will be required to have prior experience working as a marine 
mammal observer during construction.
    PSOs will have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to 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
     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.
    The City will have at least one PSO stationed at the best possible 
vantage points in the project area to monitor during all pile driving 
activities. If a PSO sights a marine mammal in the shutdown zone, the 
PSO should notify the equipment operator to shut down. The PSO will let 
the contractor know when activities can re-commence. Additional PSOs 
may be employed during periods of low or obstructed visibility to 
ensure the entirety of the shutdown zones are monitored. A marine 
mammal monitoring plan will be developed and submitted to NMFS for 
approval prior to commencing in-water construction activities.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving activities for each 
IHA, or 60 days prior to a requested date of issuance of any future 
IHAs for the project, or other projects at the same location, whichever 
comes first. The marine mammal monitoring report will include an 
overall description of work completed, a narrative regarding marine 
mammal sightings, and associated PSO datasheets. Specifically, the 
report will include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including: (a) How many and what type of piles were 
driven or removed and the method (i.e., impact or vibratory); and (b) 
the total duration of time for each pile (vibratory driving) or number 
of strikes for each pile (impact driving);
     PSO locations during marine mammal monitoring; and
     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.
    PSOs will record all incidents of marine mammal occurrence, 
regardless of distance from activity, and will document any behavioral 
reactions in concert with distance from piles being driven or removed. 
Specifically, PSOs will record the following:
     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 location of each observed marine mammal 
relative to the pile being driven or hole being drilled for each 
sighting;
     Estimated number of animals (min/max/best estimate);
     Estimated number of animals by cohort (adults, juveniles, 
neonates, group composition, etc.);
     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, or flushing);
     Number of marine mammals detected within the harassment 
zones, by species; and
     Detailed information about implementation of any 
mitigation (e.g., shutdowns and delays), a description of specified 
actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    If no comments are received from NMFS within 30 days, the draft 
report will constitute the final report. If comments are received, a 
final report addressing NMFS' comments will be required to be submitted 
within 30 days after receipt of comments. All PSO datasheets and/or raw 
sighting data will be submitted with the draft marine mammal report.
    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the City will report the 
incident to the Office of Protected Resources (OPR), NMFS 
([email protected]) and to the West Coast regional 
stranding network (866-767-6114) as soon as feasible. If the death or 
injury was clearly caused by the specified activity, the City must 
immediately cease the activities until NMFS OPR 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 
IHAs. The City will not resume their activities until notified by NMFS.
    The report will include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.

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 impacts or responses (e.g., intensity, duration), 
the context of any

[[Page 27461]]

impacts or responses (e.g., critical reproductive time or location, 
foraging impacts affecting energetics), as well as effects on habitat, 
and the likely effectiveness of the mitigation. We also assess the 
number, intensity, and context of estimated takes by evaluating this 
information relative to population status. Consistent with the 1989 
preamble for NMFS' implementing regulations (54 FR 40338, September 29, 
1989), the impacts from other past and ongoing anthropogenic activities 
are incorporated into this analysis via their impacts on the baseline 
(e.g., as reflected in the regulatory status of the species, population 
size and growth rate where known, ongoing sources of human-caused 
mortality, or ambient noise levels).
    To avoid repetition, the discussion of our analysis applies to 
California sea lions and harbor seals, given that the anticipated 
effects of this activity on these different marine mammal stocks are 
expected to be similar. Where there are meaningful differences between 
these species, in anticipated individual responses to activities, 
impact of expected take on the population due to differences in 
population status, or impacts on habitat, they are described 
independently in the analysis below.
    Pile installation and removal 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 and, 
for harbor seals, Level A harassment, from underwater sounds generated 
from impact pile installation and vibratory pile installation and 
removal activities. Potential takes could occur if individuals move 
into the ensonified zones when these activities are underway.
    No serious injury or mortality will be expected, even in the 
absence of required mitigation measures, given the nature of the 
activities. Further, no take by Level A harassment is anticipated for 
California sea lions due to the application of planned mitigation 
measures, such as shutdown zones that encompass the Level A harassment 
zones for this species. The potential for harassment will be minimized 
through the construction method and the implementation of the planned 
mitigation measures (see Mitigation section).
    Take by Level A harassment is authorized for harbor seals during 
Year 2 as the Level A harassment zone for impact pile driving exceeds 
the size of the shutdown zone for this activity. Therefore, there is 
the possibility that an animal could enter a Level A harassment zone 
without being detected, and remain within that zone for a duration long 
enough to incur PTS. Any take by Level A harassment is expected to 
arise from, at most, a small degree of PTS (i.e., minor degradation of 
hearing capabilities within regions of hearing that align most 
completely with the energy produced by impact pile driving, such as the 
low-frequency region below 2 kHz), not severe hearing impairment or 
impairment within the ranges of greatest hearing sensitivity. 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.
    Further, the amount of take by Level A harassment authorized for 
these species is very low. For California sea lions, NMFS anticipates 
and has authorized no Level A harassment take over the duration of the 
City's planned activities; for harbor seals, NMFS has authorized no 
take by Level A harassment in Year 1 and no more than 74 takes by Level 
A harassment in Year 2. If hearing impairment occurs, it is most likely 
that the affected animal would lose only a few decibels in its hearing 
sensitivity. Due to the small degree anticipated, any PTS potential 
incurred would not be expected to affect the reproductive success or 
survival of any individuals, much less result in adverse impacts on the 
species or stock.
    The takes from Level B harassment will be due to potential 
behavioral disturbance. On the basis of reports in the literature as 
well as monitoring from other similar activities, effects will likely 
be limited to reactions such as avoidance, increased swimming speeds, 
increased surfacing time, or decreased foraging (if such activity were 
occurring) (e.g., Thorson and Reyff, 2006; NAVFAC SW, 2018). Most 
likely, individuals will simply move away from the sound source and 
temporarily avoid the area where pile driving is occurring. If sound 
produced by project activities is sufficiently disturbing, animals are 
likely to simply avoid the area while the activities are occurring. 
Marine mammals could also experience TTS if they move into the Level B 
monitoring zone. TTS is a temporary loss of hearing sensitivity when 
exposed to loud sound, and the hearing threshold is expected to recover 
completely within minutes to hours. Thus, it is not considered an 
injury. While TTS could occur, it is not considered a likely outcome of 
this activity. We expect that any avoidance of the project areas by 
marine mammals will be temporary in nature and that any marine mammals 
that avoid the project areas during construction will not be 
permanently displaced. Short-term avoidance of the project areas and 
energetic impacts of interrupted foraging or other important behaviors 
is unlikely to affect the reproduction or survival of individual marine 
mammals, and the effects of behavioral disturbance on individuals is 
not likely to accrue in a manner that will affect the rates of 
recruitment or survival of any affected stock. The potential for 
harassment is minimized through construction methods and the 
implementation of planned mitigation strategies (see Mitigation 
section).
    Anticipated and authorized takes are expected to be limited to 
short-term Level A (potential PTS) and Level B harassment (behavioral 
disturbance) as construction activities will occur over the course of 
14 days in Year 1 and 98 days in Year 2. Take will also occur within a 
limited, confined area of each stock's range. Level A 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 extremely small when compared to stock 
abundance.
    No marine mammal stocks for which incidental take is authorized are 
listed as threatened or endangered under the ESA or determined to be 
strategic or depleted under the MMPA. The relatively low marine mammal 
occurrences in the area, small shutdown zones, and monitoring make 
injury takes of marine mammals unlikely. The shutdown zones will be 
thoroughly monitored before the pile installation or removal begins, 
and construction activities will be postponed if a marine mammal is 
sighted within the shutdown zone. There is a high likelihood that 
marine mammals will be detected by trained observers under 
environmental conditions described for the project. Therefore, the 
mitigation and monitoring measures are expected to reduce the amount 
and intensity for Level A and Level B behavioral harassment. 
Furthermore, the pile installation and removal activities analyzed here 
are similar to, or less impactful than, numerous construction 
activities conducted in other similar locations, which have occurred 
with no reported injuries or mortality to marine mammals, and no known 
long-term adverse consequences from behavioral harassment.
    The project is not expected to have significant adverse effects on 
marine mammal habitat. There are no Biologically Important Areas or 
ESA-designated critical habitat within the project area, and activities 
will not permanently modify existing marine mammal habitat. The 
activities may

[[Page 27462]]

cause fish to leave the area temporarily. This could impact marine 
mammals' foraging opportunities in a limited portion of the foraging 
range, however, due to the short duration of activities and the 
relatively small area of affected habitat, the impacts to marine mammal 
habitat are not expected to cause significant or long-term negative 
consequences.
    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 reproduction or survival of any individual 
marine mammals, much less affect 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 any of the species or stocks 
through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     No Level A harassment of California sea lions is 
authorized;
     The small Level A harassment takes of harbor seals 
authorized are expected to be of a small degree;
     The intensity of anticipated takes by Level B harassment 
is relatively low for all stocks. Level B harassment will primarily be 
in the form of behavioral disturbance, resulting in avoidance of the 
project areas around where pile driving or removal activities are 
occurring;
     Biologically important areas or critical habitat have not 
been identified within the project area;
     The lack of anticipated significant or long-term effects 
to marine mammal habitat;
     Effects on marine mammal prey species are expected to be 
short-term and, therefore, any associated impacts on marine mammal 
feeding are not expected to result in significant or long-term 
consequences for individuals, or to accrue to adverse impacts on their 
populations; and
     The efficacy of the mitigation measures in reducing the 
effects of the specified activities on all species and stocks.
    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 
activity will have a negligible impact on all affected marine mammal 
species or stocks.

Small Numbers

    As noted previously, 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 has authorized is below one-third of the 
estimated stock abundance for all impacted stocks (Table 8). (In fact, 
take of individuals is less than 4 percent of the abundance for all 
affected stocks.) The number of takes authorized are small relative to 
the relevant stocks or populations, even if each estimated take 
occurred to a new individual. Furthermore, these takes are likely to 
only occur within a small portion of the each stock's range and the 
likelihood that each take will occur to a new individual is low.
    Based on the analysis contained herein of the 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 will 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 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 consults internally whenever we propose to authorize take for 
endangered or threatened species.
    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 two consecutive IHAs to the City for the potential 
harassment of small numbers of harbor seals and California sea lions 
incidental to the seismic retrofit of the Murray St. Bridge project in 
Santa Cruz, California, provided the previously mentioned mitigation, 
monitoring, and reporting requirements are followed.

    Dated: April 26, 2023.
Kimberly Damon-Randall
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-09193 Filed 5-1-23; 8:45 am]
BILLING CODE 3510-22-P