Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to U.S. Navy Maintenance and Pile Replacement Project in Puget Sound, Washington, 25580-25608 [2024-07676]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 89, Number 71 (Thursday, April 11, 2024)]
[Notices]
[Pages 25580-25608]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-07676]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD681]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to U.S. Navy Maintenance and Pile 
Replacement Project in Puget Sound, Washington

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

ACTION: Notice; proposed incidental harassment authorizations; request 
for comments on proposed authorizations and possible renewal.

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SUMMARY: NMFS has received a request from the United States Navy (Navy) 
for authorization to take marine mammals incidental to 2 years of 
construction activities associated with the Naval Facilities 
Engineering Command Northwest (NAVFAC NW) Maintenance and Pile 
Replacement (MPR) project in Puget Sound, Washington. Pursuant to the 
Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its 
proposal to issue two consecutive 1-year incidental harassment 
authorizations (IHAs) to incidentally take marine mammals during the 
specified activities. NMFS is also requesting comments on a possible 
one-time, 1-year renewal that could be issued under certain 
circumstances and if all requirements are met, as described in Request 
for Public Comments at the end of this notice. NMFS will consider 
public comments prior to making any final decision on the issuance of 
the requested MMPA authorizations and agency responses will be 
summarized in the final notice of our decision.

DATES: Comments and information must be received no later than May 13, 
2024.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, NMFS 
and should be submitted via email to [email protected]. 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.
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT: Kate Fleming, Office of Protected 
Resources, NMFS, (301) 427-8401.

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

[[Page 25581]]

``mitigation''); and requirements pertaining to the monitoring and 
reporting of the takings. The definitions of all applicable MMPA 
statutory terms cited above are included in the relevant sections 
below.

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 two 
consecutive IHAs) 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 NAO 216-6A, which do not 
individually or cumulatively have the potential for significant impacts 
on the quality of the human environment and for which we have not 
identified any extraordinary circumstances that would preclude this 
categorical exclusion. Accordingly, NMFS has preliminarily determined 
that the issuance of the proposed IHAs qualifies to be categorically 
excluded from further NEPA review.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
request for two consecutive IHAs.

Summary of Request

    On October 5, 2023, NMFS received a request from the Navy for two 
consecutive 1-year IHAs to take marine mammals incidental to 
construction associated with the Navy's NAVFAC NW MPR project in Puget 
Sound, Washington. Following NMFS' review of the application, the Navy 
submitted a revised version on December 14, 2023, additional 
information on January 10, 2024, and the marine mammal monitoring plan 
on January 23, 2024. Final revisions to both the application and the 
marine mammal monitoring plan were provided on March 2, 2024. The 
application was deemed adequate and complete on February 27, 2024. The 
Navy's request is for take of 10 species of marine mammals by Level B 
harassment and, for harbor seal, Level B and Level A harassment. 
Neither the Navy nor NMFS expect serious injury or mortality to result 
from this activity. Therefore, IHAs are appropriate.
    NMFS previously issued a regulation and associated Letters of 
Authorization to the Navy for related work (84 FR 15963, April 17, 
2019; https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-marine-structure-maintenance-and-pile-replacement-wa). The Navy complied with all the requirements (e.g., 
mitigation, monitoring, and reporting) of the previous LOAs, and 
information regarding their monitoring results may be found in the 
Effects of Specified Activities on Marine Mammals and Their Habitat.

Description of Proposed Activity

Overview

    Maintaining existing wharfs and piers is vital to sustaining the 
Navy's mission and ensuring readiness. To ensure continuance of 
necessary missions at the four installations, the Navy must conduct 
annual maintenance and repair activities at existing marine waterfront 
structures, including removal and replacement of piles of various types 
and sizes. The Navy refers to this program as the Marine Structure MPR 
program.
    The activities that have the potential to take marine mammals by 
Level A harassment and Level B harassment include installation and/or 
removal of timber, concrete, and steel piles by vibratory and impact 
pile driving and down-the hole (DTH) drilling. Construction would span 
the course of 2 years, with the first year beginning on July 15, 2024, 
and lasting through July 14, 2025. The second year of construction 
activities would begin July 15, 2025, and continue through July 14, 
2026.
    The Navy has requested the issuance of two consecutive IHAs in 
association with the two project years. Given the similarities in 
activities between project years, NMFS is issuing this single Federal 
Register notice to solicit public comments on the issuance of the two 
similar, but separate, IHAs.

Dates and Duration

    The Navy anticipates that the planned NAVFAC NW MPR activities will 
occur over 2 years. The year 1 IHA would be valid from July 1, 2024-
June 30, 2025, and the year 2 would span July 1, 2025-June 30, 2026. 
The specified activities would occur at any time during each project 
year, subject to existing time of year restrictions, or in-water work 
windows, designed to protect fish species listed under the U.S. 
Endangered Species Act (ESA). For Naval Base Kitsap (NBK) Bangor 
(located in Hood Canal), in-water work would occur from July 16 through 
January 15 each project year. At the remaining three facilities 
(located in Puget Sound), in-water work would occur from July 16 
through February 15.
    Days of pile driving at each site were based on the estimated work 
days using a slow production rate (e.g., four-six piles per day for 
fender pile replacement). These conservative rates are the basis for 
estimates of total days at each facility each year (table 1, table 2). 
These totals include both extraction and installation of piles and 
represent a conservative estimate of pile driving days at each 
facility. In a real construction situation, pile driving production 
rates would be maximized when possible and actual daily production 
rates may be higher, resulting in fewer actual pile driving days.

Specific Geographic Region

    The four installations are located within the inland waters of 
Washington State. One facility is located within Hood Canal, while the 
remainder are located within Puget Sound. See figure 1-1 of the Navy's 
application for a regional map and section 2 for full details regarding 
the specified geographical region. Puget Sound is one of the largest 
estuaries in the United States and is a place of great physical and 
ecological complexity and productivity. With nearly six million people 
(doubled since the 1960s), Puget Sound is also heavily influenced by 
human activity.
    NBK Bangor serves as the Pacific homeport for the Navy's TRIDENT 
submarine squadron and other ships home-ported or moored at the 
installation and to maintain and operate administrative and personnel 
support facilities including security, berthing, messing, and 
recreational services. It is located on Hood Canal, a long, narrow, 
fjord-like basin of western Puget Sound (see figure 1-2 of the Navy's 
application). Oriented northeast to southwest, the portion of the canal 
from Admiralty Inlet to a large bend, called the Great Bend, at 
Skokomish, Washington, is 84 kilometers (km) (52 miles (mi)) long. East 
of the Great Bend, the canal extends an additional 24 km (15 mi) to 
Belfair. Throughout its 108-km (67 mi) length, the width of the canal 
varies from 1.6 to 3.2 km (1 to 2 mi) and exhibits strong depth/
elevation gradients. Hood Canal is characterized by relatively steep 
sides and irregular seafloor topography. In northern Hood Canal, water 
depths in the center of the waterway near Admiralty Inlet vary between 
91 and 128 meters (m) (300 and 420 feet (ft)). As the canal extends 
southwestward toward the Olympic Mountain Range and Thorndyke Bay, 
water depth decreases to approximately 49 m (160 ft) over a moraine 
deposit. This deposit forms a sill across the canal

[[Page 25582]]

in the vicinity of Thorndyke Bay, which limits seawater exchange with 
the rest of Puget Sound. The NBK Bangor waterfront occupies 
approximately 8 km (5 mi) of the shoreline within northern Hood Canal 
(1.7 percent of the entire Hood Canal coastline) and lies just south of 
the sill feature.
    NBK Bremerton serves as the homeport for a nuclear aircraft carrier 
and other Navy vessels. It is located on the north side of Sinclair 
Inlet in southern Puget Sound (see figure 1-3 of the Navy's 
application). Sinclair Inlet is located off the main basin of Puget 
Sound and is about 6.9 km long and 1.9 km wide. The inlet is connected 
to the main basin through Port Orchard Narrows and Rich Passage. 
Another relatively narrow waterway, Port Washington Narrows, connects 
Sinclair Inlet to Dyes Inlet. In-water structures, shoreline fill, and 
erosion protection at NBK Bremerton have resulted in a shoreline 
geometry and character that is quite different from undisturbed 
shorelines in Puget Sound. Bathymetry near existing piers and in 
turning basins immediately offshore has been altered by significant 
dredging to accommodate aircraft carriers and other Navy vessels. Water 
depths range from 12 to 14 m (40 to 45 ft), increasing to 14 to 15 m 
(45 to 50 ft) in dredged berthing areas. West of the project sites, 
further into Sinclair Inlet, depths gradually decrease to less than 9 m 
(30 ft).
    NBK Manchester provides bulk fuel and lubricant support to area 
Navy afloat and shore activities. It is located on Orchard Point, 
approximately 6.4 km (4 mi) due east of Bremerton. Please see figure 1-
4 of the Navy's application. The installation is bounded by Clam Bay to 
the northwest, Rich Passage to the northeast, and Puget Sound to the 
east. NBK Manchester piers are located on the north side of Orchard 
Point and in a small embayment open on the south side of Orchard Point. 
In Clam Bay, the bathymetry is gently sloping with depths in the outer 
portions of the bay of approximately 5.5 m (18 ft) below mean lower low 
water (MLLW). Depths off Orchard Point drop off dramatically to 18 m 
(60 ft) below MLLW approximately 150 m (500 ft) from shore and 90 m 
(300 ft) below MLLW 1.6 km (1 m) offshore. Rich Passage is a shallow 
sill, less than 21 m (70 ft) deep.
    Naval Station (NS) Everett provides homeport ship berthing, 
industrial support, and a Navy administrative center. It is located in 
Port Gardner Bay in Puget Sound's Whidbey Basin (see figure 1-5 of the 
Navy's application). To the west of the installation is the channelized 
mouth of the Snohomish River bounded by Jetty Island, which is composed 
of sediment from maintenance dredging and acts as a breakwater for the 
northwest area along the installation's waterfront. Jetty Island 
separates Port Gardner Bay and Possession Sound from the Snohomish 
River channel. The mouth of the Snohomish River channel is a 
historically industrialized area of highly modified shorelines and 
dredged waterways that forms a protected harbor within Port Gardner 
Bay. East of Jetty Island lies the Snohomish River estuary, consisting 
of a series of interconnected sloughs that flow through the lowlands 
east and north of the river's main channel. Water depths in Possession 
Sound range from about 9 m (30 ft) near the industrialized shoreline in 
Port Gardner to 180 m (600 ft) in mid-channel.

Detailed Description of the Specified Activity

    The Navy plans to conduct maintenance and repair activities at 
marine waterfront structures at the four aforementioned installations 
within Puget Sound (Washington inland waters) and Hood Canal. Repairs 
would include replacing up to 150 structurally unsound piles with 164 
concrete or steel piles over a 1-year period (July 2024 through July 
2025) at NBK Bremerton and NBK Manchester using impact and vibratory 
pile driving and removal and DTH drilling; and replacing 130 
structurally unsound piles over a 1-year period (July 2025-July 2026) 
at NBK Bremerton, NBK Bangor and NS Everett using impact and vibratory 
pile driving and removal.
    Tables 1 and 2 provide a summary of pile types, sizes, and maximum 
numbers of piles at each installation to be replaced over the two 1-
year MPR Program periods from July 2024-July 2025 and July 2025-July 
2026, respectively. This estimate assumes all piles would be removed 
and replaced with new piles. However, existing piles may be repaired in 
place with no new piles installed and if replaced piles are larger than 
existing piles, typically fewer piles are needed. Therefore, estimates 
of replaced piles for each installation are a conservative 
overestimate. These estimates also include temporary (or ``false 
work'') piles that may be required during construction. Actual numbers 
will depend on the number actually replaced and the size and type of 
new piles installed.
    The MPR program includes pile repair, extraction, and installation, 
all of which may be accomplished through a variety of methods. However, 
only pile extraction and installation using vibratory and impact pile 
drivers and DTH drilling are expected to have the potential to result 
in incidental take of marine mammals. Pile repair methods include 
stubbing, wrapping, pile encapsulation, welding, or coating. These 
processes do not involve pile driving and are not expected to have the 
potential to result in incidental take of marine mammals. Pile removal 
may be accomplished via vibratory extraction or via mechanical methods 
such as cutting/chipping, clamshell removal, or direct pull. Four 
primary methods of pile installation would be used: water jetting, 
vibratory pile driving, impact pile driving, or DTH drilling. Noise 
levels produced through mechanical extraction activities and water 
jetting are not expected to exceed baseline levels produced by other 
routine activities and operations at the four facilities, and any 
elevated noise levels produced through these activities are expected to 
be intermittent, of short duration, and with low peak values. 
Therefore, only impact and vibratory pile driving, vibratory removal, 
and DTH drilling are carried forward for further analysis.
    Vibratory hammers, which can be used to either install or extract a 
pile, contain a system of counter-rotating eccentric weights powered by 
hydraulic motors, and are designed in such a way that horizontal 
vibrations cancel out, while vertical vibrations are transmitted into 
the pile. The pile driving machine is lifted and positioned over the 
pile by means of an excavator or crane, and is fastened to the pile by 
a clamp and/or bolts. The vibrations produced cause liquefaction of the 
substrate surrounding the pile, enabling the pile to be extracted or 
driven into the ground using the weight of the pile plus the hammer. 
Impact hammers use a rising and falling piston to repeatedly strike a 
pile and drive it into the ground. DTH drilling is a common method used 
to drill holes through hard rock substrates. DTH drilling uses rotary 
cutting percussion action using a button bit. In DTH drilling, the 
drill pipe transmits the necessary feed force and rotation to the 
hammer and bit, along with the compressed air used to actuate the 
hammer and flush the cuttings.

[[Page 25583]]



  Table 1--Pile Types and Maximum Anticipated Number To Be Replaced at Each Installation Between July 2024 and
                                                    July 2025
----------------------------------------------------------------------------------------------------------------
                                                                                                      Days of
          Pile size/type                  Method           Number of    Estimated  piles per day   installation
                                                             piles                                  or removal
----------------------------------------------------------------------------------------------------------------
                                        NBK Bremerton (Pier C and Pier 5)
----------------------------------------------------------------------------------------------------------------
13-inch Timber...................  Removal, Vibratory               78  6 (up to 10)............              30
                                    or Pull
24-in Concrete Octagonal.........  Installation,                    25  4.......................
                                    Impact
18-in x 18-inch square concrete..  Installation,                    65  5.......................
                                    Impact
----------------------------------------------------------------------------------------------------------------
                                           NBK Manchester (Fuel Pier)
----------------------------------------------------------------------------------------------------------------
26-in Steel......................  Removal, Pull or                 72  N/A.....................              37
                                    Cut
24-in Concrete...................  Installation, DTH                74  1-2.....................
                                    or impact
----------------------------------------------------------------------------------------------------------------


  Table 2--Pile Types and Maximum Anticipated Number To Be Replaced at Each Installation Between July 2025 and
                                                    July 2026
----------------------------------------------------------------------------------------------------------------
                                                                                                      Days of
            Pile size/type                       Method              Number of       Estimated     installation
                                                                       piles       piles per day    or removal
----------------------------------------------------------------------------------------------------------------
                                            NBK Bangor Marginal Wharf
----------------------------------------------------------------------------------------------------------------
36-inch Steel.........................  Removal, Vibratory or                 78               4              36
                                         Pull
                                        Installation, Vibratory               78               4
                                         or Impact
----------------------------------------------------------------------------------------------------------------
                                             NBK Bremerton (Pier F)
----------------------------------------------------------------------------------------------------------------
24-in Steel...........................  Removal, Vibratory                    48             1-6              24
                                        Installation, Vibratory               48
----------------------------------------------------------------------------------------------------------------
                                               NS Everett (Pier A)
----------------------------------------------------------------------------------------------------------------
12-in Steel...........................  Removal, Vibratory or                  4             1-2               8
                                         Cut
                                        Installation, Vibratory                4             1-2
                                         or Impact
----------------------------------------------------------------------------------------------------------------

    Between July 2024 and July 2025, the following activities are 
planned: (1) At NBK Bremerton, 25 13-inch (in) timber fender piles 
would be removed at Pier C using vibratory pile driving or pulling and 
replaced with 25 24-in concrete fender piles using impact pile driving. 
At the same installation, 53 13-in timber piles would be vibratory 
removed at Pier 5 and replaced with up to 65 18-in concrete piles using 
impact pile driving. Impact pile driving at Pier 5 may occur at the 
same time as vibratory pile driving at Pier C, though Pier 5 is 
shielded from Pier C pile driving sound by Dry Dock 6, which is a solid 
structure extending into Sinclair Inlet; and (2) At NBK Manchester a 
total of 72 26-in steel piles would be removed and replaced with 74 24-
in concrete piles at the Fuel Pier. Concrete piles would be installed 
using DTH drilling in areas with bedrock while impact pile driving 
would be used if there is no bedrock.
    Between July 2025 and July 2026, the following activities are 
planned: (1) Up to 78 steel fender piles (36-in) at NBK Bangor are 
anticipated to be removed by vibratory pile driving or cutting, and 78 
steel fender piles (36-in) could be installed using vibratory pile 
driving with impact proofing at this same location; (2) A total of 48 
24-in steel fender piles would be removed and replaced with 48 new 24-
in steel fender piles using vibratory pile driving at NBK Bremerton, 
Pier F; and (3) At NS Everett a total of 4 12-in steel piles will be 
removed by vibratory pile driving or cutting and replaced with 4 12-in 
steel piles by vibratory or impact pile driving if necessary at Pier A.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the 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, instead of reprinting the information. Additional 
information regarding population trends and threats may be found in 
NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 3 lists all species or stocks for which take is expected and 
proposed to be authorized for both proposed IHAs, and summarizes 
information related to the population or stock, including regulatory 
status under the MMPA and ESA and potential biological removal (PBR), 
where known. PBR is defined by the MMPA as the maximum number of 
animals, not including natural mortalities, that may be removed from a 
marine mammal stock while allowing that stock to reach or maintain its 
optimum sustainable population (as described in NMFS' SARs). While no 
serious injury or mortality is anticipated or proposed to be authorized 
here, PBR and annual serious injury and mortality from anthropogenic 
sources are included here as gross indicators of the

[[Page 25584]]

status of the species or stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Alaska and Pacific SARs. All values presented in table 3 are 
the most recent available at the time of publication (including from 
the draft 2023 SARs) and are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                  Table 3--Marine Mammal Species \4\ Likely To Be Affected 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 Artiodactyla--Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
    Gray Whale......................  Eschrichtius robustus..  Eastern N Pacific......  -, -, N             26,960 (0.05, 25,849,         801        131
                                                                                                             2016).
Family Balaenopteridae (rorquals):
    Humpback Whale..................  Megaptera novaeangliae.  Central America/         E, D, Y             1,494 (0.171, 1,284,          3.5       14.9
                                                                Southern Mexico--CA/OR/                      2021).
                                                                WA.
                                                               Mainland Mexico--CA/OR/  T, D, Y             3,477 (0.101, 3,185,           43         22
                                                                WA.                                          2018).
                                                               Hawai'i................  -, -, N             11,278 (0.56, 7,265,          127      27.09
                                                                                                             2020).
    Minke Whale.....................  Balaenoptera             CA/OR/WA...............  -, -, N             915 (0.792, 509, 2018)        4.1       0.19
                                       acutorostrata.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer Whale....................  Orcinus orca...........  Eastern North Pacific    E, D, Y             73 (N/A, 73, 2022)....       0.13          0
                                                                Southern Resident.
                                                               West Coast Transient...  -, -, N             349 \5\ (N/A, 349,            3.5        0.4
                                                                                                             2018).
Family Phocoenidae (porpoises):
    Dall's Porpoise.................  Phocoenoides dalli.....  CA/OR/WA...............  -, -, N             16,498 (0.61, 10,286,          99     >=0.66
                                                                                                             2018).
    Harbor Porpoise.................  Phocoena phocoena......  Washington Inland        -, -, N             11,233 (0.37, 8,308,           66      >=7.2
                                                                Waters.                                      2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    CA Sea Lion.....................  Zalophus californianus.  U.S....................  -, -, N             257,606 (N/A, 233,515,     14,011       >321
                                                                                                             2014).
    Steller Sea Lion................  Eumetopias jubatus.....  Eastern................  -, -, N             36,308 \6\ (N/A,            2,178       93.2
                                                                                                             36,308, 2022).
Family Phocidae (earless seals):
    Harbor Seal.....................  Phoca vitulina.........  Washington Inland Hood   -, -, N             3,363 (0.16, 2,940,            88          2
                                                                Canal.                                       2019).
 
                                                               Washington Northern      -, -, N             16,451 (0.07, 15,462,         928         40
                                                                Inland Waters.                               2019).
    Northern Elephant Seal..........  Mirounga angustirostris  CA Breeding............  -, -, N             187,386 (N/A, 85,369,       5,122       13.7
                                                                                                             2013).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 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 SARs online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region.
  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.
\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/).
\5\ Nest is based upon count of individuals identified from photo-ID catalogs in analysis of a subset of data from 1958-2018.
\6\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the U.S.
  only.

    As indicated above, all 10 species (with 14 managed stocks) in 
table 3 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. All species that could 
potentially occur in the proposed project areas are included in table 
3-1 of the application for two consecutive IHAs. While Pacific white-
sided dolphin, bottlenose dolphin, long-beaked common dolphin, and 
Risso's dolphin have been documented in the Puget Sound, 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. Additionally, the range of the southern 
Puget Sound stock of harbor seal does not overlap with the project area 
and the stock is not discussed further. These species are very rare in 
Puget Sound and are not expected to occur near any of the MPR 
installations.

[[Page 25585]]

    In addition, the northern sea otter may be found in the Puget Sound 
area. However, northern sea otters are managed by the U.S. Fish and 
Wildlife Service and are not considered further in this document.

Gray Whale

    Gray whales are observed in Washington inland waters in all months 
of the year, with peak numbers occurring from March through June 
(Calambokidis et al., 2010). Most whales sighted are part of a small 
regularly occurring group of 6 to 10 whales that use the northern Puget 
Sound as a springtime feeding area (Calambokidis et al., 2010; 
Calambokidis, 2017). Observed feeding areas are located in Saratoga 
Passage between Whidbey and Camano Islands including Crescent Harbor, 
and in Port Susan Bay located between Camano Island and the mainland 
north of Everett (Calambokidis et al., 2010). Gray whales that are not 
identified with the regularly occurring feeding group are occasionally 
sighted in Puget Sound. These whales are not associated with feeding 
areas and are often emaciated (WDFW, 2012).
    In the waterways near NBK Bremerton (Rich Passage/Sinclair Inlet/
Dyes Inlet/Agate Passage), 11 opportunistic sightings of gray whales 
were reported to the Orca Network (a public marine mammal sightings 
database) between 2003 and 2012. In October 2020, PSOs observed a gray 
whale near NBK Bangor during construction associated with a Pier 
Extension Project (DoN, 2021). PSOs were on site observing marine 
mammals for 99 days between July 2020 and January 2021 (DoN, 2021) and 
for 32 days between October 2021 and January 2022 (DoN, 2022). However, 
gray whales were not observed during monitoring efforts associated with 
other projects occurring at relevant Navy installations in Puget Sound. 
This includes two projects occurring at NBK Bangor: the Explosives 
Handling Wharf Pile Replacement Project (monitoring occurred on 14 days 
between August 2021 and October 2021) (Hamer Environmental, 2021), and 
the Service Pier B710 Pile Replacement Project (monitoring occurred on 
4 days between December 2021 and January 2022) (Sandoval et al., 2022), 
and one project occurring at NBK Manchester in which PSOs monitored for 
11 days between September and December 2021 for the Pier B213 Fender 
Replacement Project (Sandoval and Johnson, 2021).
    There is a Biologically Important Area (BIA) for migrating gray 
whales in the inland waters of Puget Sound from January through July 
and October through December and for feeding gray whales between March 
and May (Calambokidis et al., 2015).
    Between 2019 and 2023, there was an Unusual Mortality Event (UME) 
for gray whales occurring along the West Coast from Mexico through 
Alaska. While most of the strandings associated with this UME have been 
documented along Washington's Pacific coast, 14 gray whale strandings 
have been reported in inland waters between February and July, 2 of 
which were reported near NS Everett (May 2019 and April 2020); one at 
the mouth of Hood Canal (May 2019), and one near NBK Bremerton (March 
2021). Additionally, a gray whale spent several weeks in Dyes Inlet 
near NBK Bremerton in April and May 2023 and subsequently stranded near 
Olympia, Washington in June of that year. Gray whales are rarely 
sighted in Hood Canal south of the Hood Canal Bridge, including a 
stranded whale at Belfair State Park (Orca Network, 2022).
    Gray whales are expected to occur in the waters surrounding all 
four installations. However, gray whales are expected to occur 
primarily from March through June when in-water construction will not 
occur. Therefore, although some exposure to individual gray whales 
could occur at the four facilities, project timing will help to 
minimize potential exposures.

Humpback Whale

    On September 8, 2016, NMFS divided the once single species into 14 
distinct population segments (DPS) under the ESA, removed the species-
level listing as endangered, and, in its place, listed four DPSs as 
endangered and one DPS as threatened (81 FR 62259, September 8, 2016). 
The remaining nine DPSs were not listed. There are four DPSs in the 
North Pacific, including Western North Pacific and Central America, 
which are listed as endangered, Mexico, which is listed as threatened, 
and Hawaii, which is not listed.
    The 2022 Pacific SARs described a revised stock structure for 
humpback whales which modifies the previous stocks designated under the 
MMPA to align more closely with the ESA-designated DPSs (Caretta et 
al., 2023; Young et al., 2023). Specifically, the three previous North 
Pacific humpback whale stocks (Central and Western North Pacific stocks 
and a CA/OR/WA stock) were replaced by five stocks, largely 
corresponding with the ESA-designated DPSs. These include Western North 
Pacific and Hawaii stocks and a Central America/Southern Mexico-CA/OR/
WA stock (which corresponds with the Central America DPS). The 
remaining two stocks, corresponding with the Mexico DPS, are the 
Mainland Mexico-CA/OR/WA and Mexico-North Pacific stocks (Caretta et 
al., 2023; Young et al., 2023). The former stock is expected to occur 
along the west coast from California to southern British Columbia, 
while the latter stock may occur across the Pacific, from northern 
British Columbia through the Gulf of Alaska and Aleutian Islands/Bering 
Sea region to Russia.
    The Hawai[revaps]i stock consists of one demographically 
independent population (DIP)--Hawai[revaps]i--Southeast Alaska/Northern 
British Columbia DIP and one unit--Hawai[revaps]i--North Pacific unit, 
which may or may not be composed of multiple DIPs (Wade et al., 2021). 
The DIP and unit are managed as a single stock at this time, due to the 
lack of data available to separately assess them and lack of compelling 
conservation benefit to managing them separately (NMFS, 2023; NMFS, 
2019; NMFS, 2022b). The DIP is delineated based on two strong lines of 
evidence: genetics and movement data (Wade et al., 2021). Whales in the 
Hawai[revaps]i--Southeast Alaska/Northern British Columbia DIP winter 
off Hawai[revaps]i and largely summer in Southeast Alaska and Northern 
British Columbia (Wade et al., 2021). The group of whales that migrate 
from Russia, western Alaska (Bering Sea and Aleutian Islands), and 
central Alaska (Gulf of Alaska excluding Southeast Alaska) to 
Hawai[revaps]i have been delineated as the Hawai[revaps]i-North Pacific 
unit (Wade et al., 2021). There are a small number of whales that 
migrate between Hawai[revaps]i and southern British Columbia/
Washington, but current data and analyses do not provide a clear 
understanding of which unit these whales belong to (Wade et al., 2021) 
(Caretta et al., 2023; Young et al., 2023).
    The Mexico--North Pacific unit is likely composed of multiple DIPs, 
based on movement data (Martien et al., 2021; Wade, 2021, Wade et al., 
2021). However, because currently available data and analyses are not 
sufficient to delineate or assess DIPs within the unit, it was 
designated as a single stock (NMFS, 2023a; NMFS, 2019; NMFS, 2022c). 
Whales in this stock winter off Mexico and the Revillagigedo 
Archipelago and summer primarily in Alaska waters (Martien et al., 
2021; Carretta et al., 2023; Young et al., 2023).
    Within U.S. west coast waters, three current DPSs may occur: The 
Hawaii DPS (not listed), Mexico DPS (threatened), and Central America 
DPS (endangered). According to Wade et al. (2021), the probability that 
whales encountered in Washington waters are from a given DPS are as 
follows: Hawaii, 69 percent; Mexico (CA-OR-WA), 25 percent; Central 
America, 6 percent.

[[Page 25586]]

    Humpback whales have been reported in the Puget Sound during every 
month in 2022 (Orca Network, 2023). Most humpback whale sightings 
reported since 2003 were in the main basin of Puget Sound with numerous 
sightings in the waters between Point No Point and Whidbey Island, 
Possession Sound, and southern Puget Sound in the vicinity of Point 
Defiance. Some of the reported sightings were in the vicinity of NS 
Everett and NBK Manchester. A few sightings of possible humpback whales 
were reported by Orca Network in the waters near NBK Bremerton and 
between January 2003 and December 2015. Humpback whales were sighted in 
the vicinity of Manette Bridge in Bremerton in March and May 2016, and 
May 2017 (Orca Network, 2017), and a carcass was found under a dock at 
NBK Bremerton in June 2016 (Cascadia Research, 2016).
    In Hood Canal, single humpback whales were observed for several 
weeks in 2012 and in 2015 (Orca Network, 2022). Multiple sightings in 
Hood Canal were reported in June 2019, February through May 2020, and 
August 2021 (Orca Network, 2022). Prior to the 2012 sightings, there 
were no confirmed reports of humpback whales entering Hood Canal (Orca 
Network, 2022).
    Humpback whales were not observed by protected species observers 
(PSOs) during monitoring completed for Navy construction projects at 
NBK Bangor (DoN, 2021; DoN, 2022; Hamer Environmental, 2021; Sandoval 
et al., 2022) and NBK Manchester (Sandoval and Johnson, 2021; Sandoval 
et al., 2022; Hamer Environmental, 2021). The number of humpback whales 
potentially present near any of the four naval installations over the 
project time period is expected to be low in any month.

Minke Whale

    Sightings of minke whales in Puget Sound are infrequent, with 
approximately 14 opportunistic sightings recorded south of the 
Admiralty Inlet between 2005 and 2012, from March through October. In 
recent years (2022 and 2023), possible sightings of a single minke 
whale have been reported near NBK Bangor in September and October (the 
Orca Network 2022 and 2023), and in 2021 and 2022, a few minke whale 
sightings were reported south of Whidbey Island by the Pacific Whale 
Watch Association (Gless and Krieger, 2023). However, minke whales were 
not observed by PSOs during monitoring completed for Navy construction 
projects at NBK Bangor (DoN, 2021; DoN, 2022; Hamer Environmental, 
2021; Sandoval et al., 2022) and NBK Manchester (Sandoval and Johnson, 
2021; Sandoval et al., 2022; Hamer Environmental, 2021) and the number 
of minke whales potentially present near any of the four installations 
is expected to be very low in any month and even lower in winter 
months.

Killer Whale (Transient)

    Groups of transient killer whales were observed for lengthy periods 
in Hood Canal in 2003 (59 days) and 2005 (172 days) (London, 2006), but 
were not observed again until 2016, when they were seen on a handful of 
days between March and May (including in Dabob Bay). Transient killer 
whales were observed by PSOs in December 2020 and December 2021 during 
construction at NBK Bangor (DoN, 2021; DoN, 2022). Transient killer 
whales have been seen infrequently near NBK Bremerton, including in 
Dyes Inlet and Sinclair Inlet (e.g., sightings in 2010, 2013, 2015, 
2022, and 2023) (Orca Network, 2023). Transient killer whales have 
occasionally been observed transiting through Rich Passage near NBK 
Manchester. In 2022, transient killer whales were observed in 
Possession Sound near NS Everett.
    West Coast transient killer whales most often travel in small pods 
averaging four individuals (Baird and Dill, 1996); however, the most 
commonly observed group size in Puget Sound (waters east of Admiralty 
Inlet, including Hood Canal, through South Puget Sound and north to 
Skagit Bay) from 2004 to 2010 was 6 whales (Houghton et al., 2015). 
This is consistent with the mean group size of transient killer whales 
observed by PSOs during monitoring for year 1 of the service pier 
extension project at NBK Bangor in 2021 (DoN, 2021). Mean group size of 
killer whales observed at this site during year 2 was 5 (DoN, 2022). 
Transient killer whales were not observed by PSOs during monitoring 
completed for other Navy construction projects completed at NBK Bangor 
(Hamer Environmental, 2021; Sandoval et al., 2022) or NBK Manchester 
(Sandoval and Johnson, 2021; Sandoval et al., 2022; Hamer 
Environmental, 2021).

Killer Whale (Resident)

    Southern Resident Killer Whales (SRKW) are expected to occur 
occasionally in the waters surrounding all of the installations except 
those in Hood Canal, where they have not been reported since 1995 
(NMFS, 2006; 86 FR 41668, August 2, 2021). SRKW are rare near NBK 
Bremerton, with the last confirmed sighting in Dyes Inlet in 1997. 
Southern residents have been observed in Saratoga Passage and 
Possession Sound near NS Everett. SRKW were not observed by PSOs during 
construction activities occurring at NBK Manchester (Sandoval and 
Johnson, 2021) and NBK Bangor (DoN, 2021; DoN, 2022; Hamer 
Environmental, 2021; Sandoval et al., 2022).
    The stock contains three pods (J, K, and L pods), with pod sizes 
ranging from approximately 16 (in K pod) to 34 (in L pod) individuals. 
Group sizes encountered can be smaller or larger if pods temporarily 
separate or join together.
    Critical habitat for SRKW, designated pursuant to the ESA and 
revised in 2018 (80 FR 9366, March 5, 2018) includes three specific 
areas: (1) Summer core area in Haro Strait and waters around the San 
Juan Islands; (2) Puget Sound; and (3) Strait of Juan de Fuca. The 
primary constituent elements essential for conservation of the habitat 
are: (1) Water quality to support growth and development; (2) Prey 
species of sufficient quantity, quality, and availability to support 
individual growth, reproduction, and development, as well as overall 
population growth; and (3) Passage conditions to allow for migration, 
resting, and foraging. The Puget Sound segment of the designated 
critical habitat for SRKW is defined as the area south of the Deception 
Pass Bridge, west of the entrance to Admiralty Inlet, and north of the 
Hood Canal Bridge. Although the three naval installations that fall 
within this area are excluded from the area designated as Critical 
Habitat under the ESA, they do contain the aforementioned Primary 
Constituent Elements (PCEs). However, we note that water quality and 
habitat for prey species is generally degraded in the vicinity of these 
industrial environments relative to other areas contacting the PCEs 
that may be less impacted (see Effects of Specified Activities on 
Marine Mammals and Their Habitat section). SRKW have been observed in 
this area in all seasons but most occurrence here (especially the J 
pod) typically correlates with fall salmon runs (NMFS 2006).

Dall's Porpoise

    Dall's porpoise are known to occur in Puget Sound, and have been 
sighted as far south as Carr Inlet in southern Puget Sound and as far 
north as Saratoga Passage, north of NS Everett (Nysewander et al., 
2005; WDFW, 2008). Dall's porpoise could also occasionally occur in 
Hood Canal with the last observation in deeper water near NBK Bangor in 
2008 (Tannenbaum et al., 2009). However, Dall's porpoise were not 
observed during vessel line-transect

[[Page 25587]]

surveys and other monitoring efforts completed in Hood Canal (including 
Dabob Bay) in 2011 (HDR, 2012). Dall's porpoises have not been 
documented in the Rich Passage to Agate Passage area in the vicinity of 
NBK Bremerton, but have been observed in Possession Sound near NS 
Everett (primarily during winter) (Nysewander et al., 2005; WDFW, 
2008). Dall's porpoises could be present in waters in the vicinity of 
any of the installations considered here, and are considered more 
likely to occur during winter months than summer months in groups of up 
to 25 individuals. Dall's porpoise were not observed by PSOs during 
monitoring associated with construction activities at NBK Bangor (Hamer 
Environmental 2021, Sandoval et al., 2022; DoN, 2021; DoN 2022) and NBK 
Manchester (Sandoval and Johnson, 2021).

Harbor Porpoise

    Sightings of harbor porpoise in Hood Canal north of the Hood Canal 
Bridge have increased in recent years (Evenson et al., 2016; Elliser et 
al., 2021; Rone et al., 2024). Across three seasons, Jefferson (2016) 
estimated 185 individuals in Hood Canal based on aerial surveys 
completed in 2013-2015, and less than a decade later, Rone's (2024) 
population estimates based on vessel based surveys completed in 2022-
2023 in Hood Canal ranged from 308 individuals in the winter to 1,385 
individuals in the fall. Mean group size of harbor porpoises for each 
survey season in the 2013-2016 aerial surveys was 1.7 (Smultea et al., 
2017) and similarly, 1.6 individuals per group in Hood Canal during 
surveys completed in 2023 (Rone et al., 2024).
    Information is available on harbor porpoise occurrence in Puget 
Sound (Navy, 2019; Smultea et al., 2022) and more recently some limited 
site-specific (within 500 meters) information is available for the Navy 
installations (DoN, 2021; DoN, 2022; Sandoval and Johnson, 2022).
    PSOs associated with a service pier extension project at NBK Bangor 
monitored for 95 days between July 16, 2020 and January 13, 2021. 
Harbor porpoise were observed each month during the monitoring period, 
with peak numbers recorded in August. A total of 420 sightings of 
harbor porpoise groups were recorded during this time (DoN, 2021). The 
closest harbor porpoises came to the project site during pile driving 
operations was 75 m. Harbor porpoise were also observed during year 2 
of this project, which took place on 32 days between October 19, 2021 
and January 14, 2022. Groups of harbor porpoise were observed on 12 
occasions in October, December and January (DoN, 2022); Sightings were 
estimated to be 8,000 m from the project site during pile driving 
operations. However, porpoise sightings were notably absent in a 21 
square kilometers (km\2\) area adjacent to the NBK Bangor within the 
otherwise high-density region, during surveys completed to collect 
fine-scale marine mammal occurrence data in Hood Canal (Rone et al., 
2024).
    At NBK Manchester, a total of 17 harbor porpoise were detected by 
PSOs associated with a fender pile replacement project at Manchester 
Fuel Depot on 11 days between September 28, 2021 and December 10, 2021 
(Sandoval and Johnson, 2022).
    Finally, monitoring reports are not available for NS Everett, but 
according to the Navy's application, harbor porpoises have been 
observed infrequently at this installation. See IHA application).

California Sea Lion

    California sea lions are typically present most of the year except 
for mid-June through July in Washington inland waters, with peak 
abundance between October and April (Navy, 2023). During summer months 
and associated breeding periods, the inland waters are not considered a 
high-use area by California sea lions, as they would be returning to 
rookeries in California waters. However, as described below, surveys at 
the naval installations indicate that a few individuals may remain 
year-round (Navy, 2023).
    The Navy conducts surveys at its installations in Puget Sound that 
have sea lion haulouts. Specifically, California sea lion haul-outs 
occur at NBK Bangor, NBK Bremerton, and NS Everett (though California 
sea lions may haul out opportunistically at any location). California 
sea lions have been documented during shore-based surveys at NBK Bangor 
in Hood Canal since 2008 in all survey months, with as many as 320 
individuals observed at one time (October 2018) hauled out on 
submarines at Delta Pier and on Port Security Barrier (PSB) floats 
(Navy, 2023). Additionally, California sea lions were observed 
consistently at NBK Bangor during Navy construction projects: 557 
California Sea Lions were observed across 99 days between July 2020 and 
January 2021 (DoN, 2021); 57 were observed across 32 days between 
October 2021 and January 2022 (DoN, 2022); 44 California Sea Lions were 
observed across 14 days between August 2021 and October 2021 (Hamer 
Environmental, 2021); and 3 were observed across 4 days between 
December 2021 and January 2022, (Sandoval et al., 2022).
    California sea lions have been documented on PSB floats during 
shore- and boat-based surveys at NBK Bremerton since 2010, with as many 
as 412 individuals hauled out at one time (October 2019) (Navy, 2023).
    California sea lions have been documented during shore-based 
surveys at NS Everett from 2012 to 2022 in all survey months, with as 
many as 267 individuals hauled out at one time (April 2020) on PSB 
floats.
    California sea lions haul out on floating platforms in Clam Bay 
approximately 0.5 mi (0.8 km) offshore from the Manchester Fuel Depot's 
finger pier, and approximately 13 km (8 mi) from NBK Bremerton. PSO's 
observed a total of 276 California Sea Lions at NBK Manchester across 
11 monitoring days occurring between September and December 2021 
(Sandoval and Johnson, 2021).
    The Navy conducted surveys of sea lions on the floats from 2012 
through 2016, and 2018 through 2022. In 2020, the surveys were expanded 
to include Orchard Rocks, a haulout approximately 0.8 mi (1.3 km) 
northeast of Manchester Fuel Depot that is available at lower tides. 
Between 2012 and 2016, California sea lions were observed in every 
survey month except July and August, with as many as 130 individuals 
present in one survey in October 2014. Aerial surveys were conducted by 
WDFW from March-April 2013, July-August 2013, November 2013, and 
February 2014. These surveys detected California sea lions on the 
floating platforms during all survey months except July, with up to 54 
individuals present on one survey in November 2013. In 2018, the number 
of sea lions decreased corresponding to the removal of floats. Numbers 
subsequently increased following the reintroduction of floats in 2021. 
During this time, California sea lions were observed on the floating 
platforms during all survey months except July, with up to 212 
individuals present on 1 survey in February 2022.
    California sea lions are expected to be exposed to noise from 
project activities at NBK's Bangor, Bremerton, Manchester, and NS 
Everett because haul-outs are at these installations or nearby. 
Exposure is estimated to occur primarily from August through the end of 
the in-water work window in mid-January or mid-February.

Steller Sea Lion

    Steller sea lions have been seasonally documented in shore-based 
surveys at NBK Bangor in Hood Canal since 2008

[[Page 25588]]

with a maximum of 21 individuals observed in November 2019 (Navy, 
2023). Surveys at NBK Bangor indicate Steller sea lions begin arriving 
in September and depart by the end of May (Navy, 2023). Steller sea 
lions were not observed at NBK Bangor during construction occurring on 
14 days between August and October 2021 (Hamer Environmental, 2021), on 
4 construction days occurring between December and January 2022 
(Sandoval, 2022), or on 32 construction days between October and 
January (DoN, 2022). However, 87 Steller sea lions were observed across 
99 days between July and January 2021 (DoN, 2021).
    Steller sea lions have not been detected during shore-based surveys 
at NBK Bremerton since the surveys were initiated in 2010 (Navy, 2023). 
A Steller sea lion was sighted on a float on the floating security 
barrier during a vessel survey in 2012 (Lance, 2012 personal 
communication) and others were detected during aerial surveys conducted 
by WDFW (Jeffries, 2000).
    Steller sea lions haul out on floating platforms in Clam Bay 
approximately 0.5 mi (0.8 km) offshore from the NBK Manchester finger 
pier, and approximately 8 mi (13 km) from NBK Bremerton. The number of 
Steller sea lions in the vicinity of NBK Manchester is limited by the 
variable size and availability of floating platforms in Clam Bay. As 
discussed above, the Navy has conducted surveys of sea lions on the 
floats since November 2012; however, no surveys were conducted 
September 2013 through November 2013 and July 2017 through June 2018 
(Navy, 2023). Steller sea lions were seen in all surveyed months except 
for June, July, and August with as many as 43 individuals present in 
September 2021.
    Shore-based surveys conducted since July 2012 at NS Everett have 
rarely detected Steller sea lions. However, occasional observations 
have been reported from the PSB or in the Notch Basin, generally one at 
a time (Navy, 2023). Other than these detections on the installation's 
PSBs, the nearest known Steller sea lion haulout is 14 mi (23 km) away; 
therefore, Steller sea lions are expected to be a rare occurrence in 
waters off this installation during pile driving activities.

Harbor Seal

    Harbor seals in Washington inland waters have been divided into 
three stocks: Hood Canal, Northern Inland Waters, and Southern Puget 
Sound. The range of the northern inland waters stock includes Puget 
Sound north of the Tacoma Narrows Bridge, the San Juan Islands, and the 
Strait of Juan de Fuca, while the southern Puget Sound stock range 
includes waters south of the Tacoma Narrows Bridge. Therefore, animals 
present at NBK Bremerton, NBK Manchester, and NS Everett are most 
likely to be from the northern inland waters stock, while those present 
at NBK Bangor are expected to be from the Hood Canal stock.
    Harbor seals are expected to occur year-round at all installations 
with the greatest numbers expected at installations with nearby haulout 
sites. In Hood Canal, where NBK Bangor is located, known haulouts occur 
on the west side of Hood Canal at the mouth of the Dosewallips River 
and on the western and northern shorelines in Dabob Bay located 
approximately 8.1 mi (13 km) away. Vessel-based surveys conducted from 
2007 to 2010 at NBK Bangor observed harbor seals in every month of 
surveys (Agness & Tannenbaum, 2009; Tannenbaum et al., 2009, 2011). 
Harbor seals were routinely seen during marine mammal monitoring for 
the Navy's recent construction projects at this site (Hamer 
Environmental, 2021; Sandoval et al., 2022; DoN, 2021; DoN, 2022). 
Small numbers of harbor seals have been documented hauling out 
opportunistically at NBK Bangor (e.g., on the PSB floats, wavescreen at 
Carderock Pier, buoys, barges, marine vessels, and logs) and on man-
made floating structures. The largest number of harbor seals observed 
in a single survey was 27 individuals in October 2018.
    At NS Everett, Navy surveys were conducted regularly between 2012 
and 2016, and again beginning in 2019, at which point surveys were 
expanded to include the entire East Waterway. The largest number of 
harbor seals observed in a single survey was 578 individuals in 
September 2019 (Navy, 2023). However, log rafts were removed from the 
East Waterway in the spring of 2022 and number of seals observed per 
survey has decreased. Harbor seals occupy the waters and haulout sites 
near NS Everett year-round. Harbor seal abundance is highest July 
through October. Mother pup pairs have been observed at NS Everett each 
summer since 2018, with a peak count of 96 pups observed in August 
2021.
    No haulouts have been identified at NBK Bremerton or Manchester. 
Single harbor seals have been observed swimming in these areas or 
hauled out on nearby rocks or on floats. The nearest documented 
haulouts to NBK Bremerton are across Sinclair Inlet, approximately 0.7 
mi (1.1 km) away, and according to the Navy's application, is estimated 
to have less than 100 individuals (see IHA application). The nearest 
documented haulout to NBK Manchester is Orchard Rocks Conservation Area 
in Rich Passage, approximately 1.0 mi away. As discussed above, the 
Navy began surveying this area in June 2020, which has led to a 
dramatic increase in the number of harbor seals observed in proximity 
to Manchester Fuel Depot. A total of 25 harbor seals were observed by 
PSOs across 11 monitoring days occurring between September and December 
2021 at this Naval installation (Sandoval and Johnson, 2021). The Navy 
has counted up to 153 harbor seals hauled-out and in the water near 
Orchard Rocks in June (Navy, 2023). Blakely Rocks is another known 
haulout in the vicinity of NBK Manchester, located approximately 3.5 mi 
away on the east side of Bainbridge Island. The haulout at Blakely 
Rocks is estimated to have less than 100 individuals (Jeffries, 2012 
personal communication).

Northern Elephant Seal

    No haul-outs occur in Puget Sound with the exception of individual 
elephant seals occasionally hauling out for two to four weeks to molt, 
usually during the spring and summer and typically on sandy beaches 
(Calambokidis and Baird, 1994). These animals are usually yearlings or 
subadults and their haul-out locations are unpredictable. One male 
subadult elephant seal was observed hauled out to molt at Manchester 
Fuel Depot in 2004 and a northern elephant seal was observed north of 
NBK Bangor in Hood Canal, from Kitsap Memorial Park in August 2020 
(DoN, 2021). Northern elephant seals were not observed by PSOs during 
the Navy's other construction activities occurring at NBK Bangor (Hamer 
Environmental, 2021; Sandoval et al., 2022; DoN, 2021; DoN, 2022) or 
NBK Manchester (Sandoval and Johnson, 2021). Although regular haul-outs 
occur in the Strait of Juan de Fuca, the occurrence of elephant seals 
in Puget Sound is unpredictable and rare.

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.

[[Page 25589]]

(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 4.

                  Table 4--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 et al., 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information.

Effects of Specified Activities on Marine Mammals and Their Habitat

    This section provides a discussion of the ways in which components 
of the specified activity may impact marine mammals and their habitat. 
The Estimated Take of Marine Mammals section later in this document 
includes a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The Negligible Impact Analysis 
and Determination section considers the content of this section, the 
Estimated Take of Marine Mammals section, and the Proposed Mitigation 
section, to draw conclusions regarding the likely impacts of these 
activities on the reproductive success or survivorship of individuals 
and whether those impacts are reasonably expected to, or reasonably 
likely to, adversely affect the species or stock through effects on 
annual rates of recruitment or survival.
    Acoustic effects on marine mammals during the specified activity 
can occur from impact pile driving, and vibratory pile driving and 
removal in both years, and the use of DTH equipment in year 1 only. 
These effects may result in Level A or Level B harassment of marine 
mammals in the project area.

Description of Sound Sources

    The marine soundscape is comprised of both ambient and 
anthropogenic sounds. Ambient sound is defined as the all-encompassing 
sound in a given place and is usually a composite of sound from many 
sources both near and far (American National Standards Institute 
(ANSI), 1995). The sound level of an area is defined by the total 
acoustical energy being generated by known and unknown sources. These 
sources may include physical (e.g., waves, wind, precipitation, 
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced 
by marine mammals, fish, and invertebrates), and anthropogenic sound 
(e.g., vessels, dredging, aircraft, construction).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10 to 20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    In-water construction activities associated with the project would 
include impact pile driving, vibratory pile driving and removal, and 
use of DTH equipment (year 1 only). The sounds produced by these 
activities fall into one of two general sound types: Impulsive and non-
impulsive. Impulsive sounds (e.g., explosions, gunshots, sonic booms, 
impact pile driving) are typically transient, brief (less than 1 
second), broadband, and consist of high peak sound pressure with rapid 
rise time and rapid decay (ANSI, 1986; National Institute of 
Occupational Safety and Health (NIOSH), 1998; NMFS, 2018). Non-
impulsive sounds (e.g., aircraft, machinery operations such as drilling 
or dredging, vibratory pile driving, and active sonar systems) can be 
broadband, narrowband or tonal, brief or prolonged (continuous or 
intermittent), and typically do not have the high peak sound pressure 
with rapid rise/decay time that impulsive sounds do (ANSI, 1995; NIOSH, 
1998; NMFS, 2018). The distinction between these two sound types is 
important because they have differing potential to cause physical 
effects, particularly with regard to hearing (e.g., Ward 1997 in 
Southall et al., 2007).
    Three types of hammers would be used on this project: impact, 
vibratory, and DTH (year 1 only). Impact hammers

[[Page 25590]]

operate by repeatedly dropping and/or pushing a heavy piston onto a 
pile to drive the pile into the substrate. Sound generated by impact 
hammers is characterized by rapid rise times and high peak levels, a 
potentially injurious combination (Hastings and Popper, 2005). 
Vibratory hammers install piles by vibrating them and allowing the 
weight of the hammer to push them into the sediment. Vibratory hammers 
produce significantly less sound than impact hammers. Peak Sound 
Pressure Levels (SPLs) may be 180 dB or greater, but are generally 10 
to 20 dB lower than SPLs generated during impact pile driving of the 
same-sized pile (Oestman et al., 2009). Rise time is slower, reducing 
the probability and severity of injury, and sound energy is distributed 
over a greater amount of time (Nedwell and Edwards, 2002; Carlson et 
al., 2005).
    A DTH hammer is essentially a drill bit that drills through the 
bedrock using a rotating function like a normal drill, in concert with 
a hammering mechanism operated by a pneumatic (or sometimes hydraulic) 
component integrated into to the DTH hammer to increase speed of 
progress through the substrate (i.e., it is similar to a ``hammer 
drill'' hand tool). The sounds produced by the DTH method contain both 
a continuous, non-impulsive component from the drilling action and an 
impulsive component from the hammering effect. Therefore, we treat DTH 
systems as both impulsive and continuous, non-impulsive sound source 
types simultaneously.

Acoustic Effects

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving and removal and DTH equipment is the 
primary means by which marine mammals may be harassed from the Navy's 
specified activities. In general, animals exposed to natural or 
anthropogenic sound may experience behavioral, physiological, and/or 
physical effects, ranging in magnitude from none to severe (Southall et 
al., 2007). Generally, exposure to pile driving and removal and DTH 
noise has the potential to result in behavioral reactions (e.g., 
avoidance, temporary cessation of foraging and vocalizing, changes in 
dive behavior) and, in limited cases, auditory threshold shifts (TS). 
Exposure to anthropogenic noise can also lead to non-observable 
physiological responses such as an increase in stress hormones. 
Additional noise in a marine mammal's habitat can mask acoustic cues 
used by marine mammals to carry out daily functions such as 
communication and predator and prey detection. The effects of pile 
driving and removal and DTH noise on marine mammals are dependent on 
several factors, including but not limited to sound type (e.g., 
impulsive vs. non-impulsive), the species, age and sex class (e.g., 
adult male vs. mother with calf), duration of exposure, the distance 
between the pile and the animal, received levels, behavior at time of 
exposure, and previous history with exposure (Wartzok et al., 2003; 
Southall et al., 2007). Here we discuss physical auditory effects (TSs) 
followed by behavioral effects and potential impacts on habitat.
    NMFS defines a noise-induced TS as a change, usually an increase, 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018). The amount of TS is customarily expressed in dB. A 
TS can be permanent or temporary. As described in NMFS (2018), there 
are numerous factors to consider when examining the consequence of TS, 
including, but not limited to, the signal temporal pattern (e.g., 
impulsive or non-impulsive), likelihood an individual would be exposed 
for a long enough duration or to a high enough level to induce a TS, 
the magnitude of the TS, time to recovery (seconds to minutes or hours 
to days), the frequency range of the exposure (i.e., spectral content), 
the hearing and vocalization frequency range of the exposed species 
relative to the signal's frequency spectrum (i.e., how animal uses 
sound within the frequency band of the signal; e.g., Kastelein et al., 
2014), and the overlap between the animal and the source (e.g., 
spatial, temporal, and spectral).
    Permanent Threshold Shift (PTS)--NMFS defines PTS as a permanent, 
irreversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). Available data 
from humans and other terrestrial mammals indicate that a 40 dB TS 
approximates PTS onset (Ward et al., 1958; Ward et al., 1959; Ward, 
1960; Kryter et al., 1966; Miller, 1974; Henderson et al., 2008). PTS 
levels for marine mammals are estimates, because there are limited 
empirical data measuring PTS in marine mammals (e.g., Kastak et al., 
2008), largely due to the fact that, for various ethical reasons, 
experiments involving anthropogenic noise exposure at levels inducing 
PTS are not typically pursued or authorized (NMFS, 2018).
    Temporary Threshold Shift (TTS)--NMFS defines TTS as a temporary, 
reversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). Based on data from 
cetacean TTS measurements (Southall et al., 2007), a TTS of 6 dB is 
considered the minimum TS clearly larger than any day-to-day or 
session-to-session variation in a subject's normal hearing ability 
(Schlundt et al., 2000; Finneran et al., 2000; Finneran et al., 2002). 
As described in Finneran (2016), marine mammal studies have shown the 
amount of TTS increases with cumulative sound exposure level 
(SELcum) in an accelerating fashion: At low exposures with 
lower SELcum, the amount of TTS is typically small and the 
growth curves have shallow slopes. At exposures with higher 
SELcum, the growth curves become steeper and approach linear 
relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in Masking, 
below). For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that takes place during a time when the animal is traveling 
through the open ocean, where ambient noise is lower and there are not 
as many competing sounds present. Alternatively, a larger amount and 
longer duration of TTS sustained during time when communication is 
critical for successful mother/calf interactions could have more 
serious impacts. We note that reduced hearing sensitivity as a simple 
function of aging has been observed in marine mammals, as well as 
humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise, and Yangtze finless porpoise (Neophocoena 
asiaeorientalis) and five species of pinnipeds exposed to a limited 
number of sound sources (i.e., mostly tones and octave-band noise) in 
laboratory settings (Finneran, 2015). TTS was not observed in trained 
spotted (Phoca largha) and ringed (Pusa hispida) seals exposed to 
impulsive noise at levels matching previous predictions of TTS onset 
(Reichmuth et al., 2016). In general, harbor seals and

[[Page 25591]]

harbor porpoises have a lower TTS onset than other measured pinniped or 
cetacean species (Finneran, 2015). Additionally, the existing marine 
mammal TTS data come from a limited number of individuals within these 
species. No data are available on noise-induced hearing loss for 
mysticetes. For summaries of data on TTS in marine mammals or for 
further discussion of TTS onset thresholds, please see Southall et al. 
(2007), Finneran and Jenkins (2012), Finneran (2015), and table 5 in 
NMFS (2018).
    Activities for this project include impact and vibratory pile 
driving, vibratory pile removal, and DTH drilling. There would likely 
be pauses in activities producing the sound during each day. Given 
these pauses and the fact that many marine mammals are likely moving 
through the project areas and not remaining for extended periods of 
time, the potential for TS declines.
    Behavioral Effects--Behavioral disturbance may include a variety of 
effects, including subtle changes in behavior (e.g., minor or brief 
avoidance of an area or changes in vocalizations), more conspicuous 
changes in similar behavioral activities, and more sustained and/or 
potentially severe reactions, such as displacement from or abandonment 
of high-quality habitat. Behavioral responses to sound are highly 
variable and context-specific, and any reactions depend on numerous 
intrinsic and extrinsic factors (e.g., species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day), as well as the interplay between factors (e.g., 
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007; 
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not 
only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al., 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review of 
studies involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). It is important to note that habituation 
is appropriately considered as a ``progressive reduction in response to 
stimuli that are perceived as neither aversive nor beneficial,'' rather 
than as, more generally, moderation in response to human disturbance 
(Bejder et al., 2009). Animals are most likely to habituate to sounds 
that are predictable and unvarying. The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure.
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely, and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al., 2004; Goldbogen et al., 2013). Variations in dive behavior may 
reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 2007; 
Melc[oacute]n et al., 2012). In addition, behavioral state of the 
animal plays a role in the type and severity of a behavioral response, 
such as disruption to foraging (e.g., Wensveen et al., 2017). An 
evaluation of whether foraging disruptions would be likely to incur 
fitness consequences considers temporal and spatial scale of the 
activity in the context of the available foraging habitat and, in more 
severe cases may necessitate consideration of information on or 
estimates of the energetic requirements of the affected individuals and 
the relationship between prey availability, foraging effort and 
success, and the life history stage of the animal.
    Respiration naturally varies with different behaviors, and 
variations in respiration rate as a function of acoustic exposure can 
be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies also have shown that species and 
signal characteristics are important factors in whether respiration 
rates are unaffected or change, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2005; Kastelein et al., 2006; 
Kastelein et al., 2018; Gailey et al., 2007; Isojunno et al., 2018).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales (Orcinus 
orca) have been observed to increase the length of their songs (Miller 
et al., 2000; Fristrup et al., 2003; Foote et al., 2004), while right 
whales have been observed to shift the frequency content of their calls 
upward while reducing the rate of calling in areas of increased 
anthropogenic noise (Parks et al., 2007; Rolland et al., 2012). In some 
cases, however, animals may cease or alter sound production in response 
to underwater sound (e.g., Bowles et al., 1994; Castellote et al., 
2012; Cerchio et al., 2014).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of

[[Page 25592]]

disturbance in marine mammals (Richardson et al., 1995). For example, 
gray whales are known to change direction--deflecting from customary 
migratory paths--in order to avoid noise from airgun surveys (Malme et 
al., 1984). Often avoidance is temporary, and animals return to the 
area once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; 
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). 
Longer-term displacement is possible, however, which may lead to 
changes in abundance or distribution patterns of the affected species 
in the affected region if habituation to the presence of the sound does 
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann 
et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, marine mammal strandings 
(Evans and England, 2001). However, it should be noted that response to 
a perceived predator does not necessarily invoke flight (Ford and 
Reeves, 2008), and whether individuals are solitary or in groups may 
influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been observed in marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates and efficiency (e.g., 
Beauchamp and Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 
2011). In addition, chronic disturbance can cause population declines 
through reduction of fitness (e.g., decline in body condition) and 
subsequent reduction in reproductive success, survival, or both (e.g., 
Harrington and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998).
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than 1 day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    To assess the strength of behavioral changes and responses to 
external sounds and SPLs associated with changes in behavior, Southall 
et al. (2007) developed and utilized a severity scale, which is a 10-
point scale ranging from no effect (labeled 0), effects not likely to 
influence vital rates (low; labeled from 1 to 3), effects that could 
affect vital rates (moderate; labeled from 4 to 6), to effects that 
were thought likely to influence vital rates (high; labeled from seven 
to nine). Southall et al. (2021) updated the severity scale by 
integrating behavioral context (i.e., survival, reproduction, and 
foraging) into severity assessment. For non-impulsive sounds (i.e., 
similar to the sources used during the proposed action), data suggest 
that exposures of pinnipeds to sources between 90 and 140 dB 
(referenced to 1 micropascal (re 1 [mu]Pa)) do not elicit strong 
behavioral responses; no data were available for exposures at higher 
received levels for Southall et al. (2007) to include in the severity 
scale analysis. Reactions of harbor seals were the only available data 
for which the responses could be ranked on the severity scale. For 
reactions that were recorded, the majority (17 of 18 individuals/
groups) were ranked on the severity scale as a 4 (defined as moderate 
change in movement, brief shift in group distribution, or moderate 
change in vocal behavior) or lower. The remaining response was ranked 
as a six (defined as minor or moderate avoidance of the sound source).
    The Navy documented marine mammals during construction activities 
at NBK Manchester (September 28 and December 10, 2021) and NBK Bangor 
(2021 and 2022) during work that preceded these proposed IHAs as well 
as during the installation of a service pier. Harbor seals were 
consistently the most frequently observed marine mammal in the area 
observed by PSOs. During pile driving activities at these 
installations, harbor seals were most commonly observed typically 
traveling and swimming, though some behaviors recorded during pile 
driving activities indicated that harbor seals were aware of the 
construction, such as less foraging reported and looking at the 
construction site or startling. Likewise California sea lions were 
observed traveling and swimming during pile driving activities, but in 
a couple instances were observed porpoising or breaching. Harbor 
porpoises were observed traveling, milling, porpoising and a gray whale 
was observed slow and fast traveling and milling. At NBK Bangor, a 
total of three harbor seals were observed foraging, socializing, 
feeding (when fish kills were apparent) during impact pile driving. 
Behavior changes noted during pile driving included startle responses, 
splashing, swimming in circles, re-entering water after being hauled 
out and looking in all directions and swimming fast.
    Stress responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness. Neuroendocrine stress responses often involve the 
hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine 
functions that are affected by stress--including immune competence, 
reproduction, metabolism, and behavior--are regulated by pituitary 
hormones. Stress-induced changes in the secretion of pituitary hormones 
have been implicated in failed reproduction, altered metabolism, 
reduced immune competence, and behavioral disturbance (e.g., Moberg, 
1987; Blecha, 2000). Increases in the circulation of glucocorticoids 
are also equated with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses

[[Page 25593]]

glycogen stores that can be quickly replenished once the stress is 
alleviated. In such circumstances, the cost of the stress response 
would not pose serious fitness consequences. However, when an animal 
does not have sufficient energy reserves to satisfy the energetic costs 
of a stress response, energy resources must be diverted from other 
functions. This state of distress will last until the animal 
replenishes its energetic reserves sufficient to restore normal 
function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995). Masking 
occurs when the receipt of a sound is interfered with by another 
coincident sound at similar frequencies and at similar or higher 
intensity, and may occur whether the sound is natural (e.g., snapping 
shrimp, wind, waves, precipitation) or anthropogenic (e.g., pile 
driving, shipping, sonar, seismic exploration) in origin. The ability 
of a noise source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions. Masking of 
natural sounds can result when human activities produce high levels of 
background sound at frequencies important to marine mammals. 
Conversely, if the background level of underwater sound is high (e.g., 
on a day with strong wind and high waves), an anthropogenic sound 
source would not be detectable as far away as would be possible under 
quieter conditions and would itself be masked.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with pile driving 
and removal that have the potential to cause behavioral harassment, 
depending on their distance from pile driving activities. Cetaceans are 
not expected to be exposed to airborne sounds that would result in 
harassment as defined under the MMPA. Airborne noise would primarily be 
an issue for pinnipeds that are swimming or hauled out near the project 
site within the range of noise levels elevated above the acoustic 
criteria. We recognize that pinnipeds in the water could be exposed to 
airborne sound that may result in behavioral harassment when looking 
with their heads above water. Most likely, airborne sound would cause 
behavioral responses similar to those discussed above in relation to 
underwater sound. For instance, anthropogenic sound could cause hauled 
out pinnipeds to exhibit changes in their normal behavior, such as 
reduction in vocalizations, or cause them to temporarily abandon the 
area and move further from the source. However, these animals would 
likely previously have been `taken' because of exposure to underwater 
sound above the behavioral harassment thresholds, which are generally 
larger than those associated with airborne sound. Thus, the behavioral 
harassment of these animals is already accounted for in these estimates 
of potential take. Therefore, we do not believe that authorization of 
additional incidental take resulting from airborne sound for pinnipeds 
is warranted, and airborne sound is not discussed further.

Anticipated Effects on Marine Mammal Habitat

    The Navy's construction activities could have localized, temporary 
impacts on marine mammal habitat and their prey by increasing in-water 
sound pressure levels and slightly decreasing water quality. Increased 
noise levels may affect acoustic habitat (see masking discussion above) 
and adversely affect marine mammal prey in the vicinity of the project 
areas (see discussion below). During DTH, impact and vibratory pile 
driving or removal, elevated levels of underwater noise would ensonify 
a portion of Puget Sound (Year 1 and Year 2) and Hood Canal (Year 2 
only) where both fishes and mammals occur and could affect foraging 
success. Additionally, marine mammals may avoid the area during 
construction, however, displacement due to noise is expected to be 
temporary and is not expected to result in long-term effects to the 
individuals or populations. Construction activities are of short 
duration and would likely have temporary impacts on marine mammal 
habitat through increases in underwater sound.
    A temporary and localized increase in turbidity near the seafloor 
would occur in the immediate area surrounding the area where piles are 
installed and removed. In general, turbidity associated with the pile 
installation is localized to about 25-ft (7.6 m) radius around the pile 
(Everitt et al., 1980). Cetaceans are not expected to be close enough 
to the project pile driving areas to experience effects of turbidity, 
and pinnipeds could avoid localized areas of turbidity. Therefore, the 
impact from increased turbidity levels is expected to be minimal for 
marine mammals. Furthermore, pile driving and removal at the project 
site would not obstruct movements or migration of marine mammals.
    In-Water Construction Effects on Potential Foraging Habitat--The 
areas likely impacted by the project are relatively small compared to 
the available habitat in Puget Sound (Year 1 and Year 2) and Hood Canal 
(Year 2 only). The total seafloor area affected by pile installation 
and removal is a small area compared to the vast foraging area 
available to marine mammals in the area. At best, the impacted areas 
provide marginal foraging habitat for marine mammals and fishes. 
Furthermore, pile driving and removal at the project site would not 
obstruct long-term movements or migration of marine mammals.
    Avoidance by potential prey (i.e., fish or, in the case of 
transient killer whales, other marine mammals) of the immediate area 
due to the temporary loss of this foraging habitat is also possible. 
The duration of fish and marine mammal avoidance of this area after 
pile driving stops is unknown, but a rapid return to normal 
recruitment, distribution, and behavior is

[[Page 25594]]

anticipated. Any behavioral avoidance by fish or marine mammals of the 
disturbed area would still leave significantly large areas of fish and 
marine mammal foraging habitat in the nearby vicinity.
    Effects on Potential Prey--Construction activities would produce 
continuous (i.e., vibratory pile driving and DTH drilling) and 
intermittent (i.e., impact driving and DTH drilling) sounds. Sound may 
affect marine mammals through impacts on the abundance, behavior, or 
distribution of prey species (e.g., crustaceans, cephalopods, fish, 
zooplankton). Marine mammal prey varies by species, season, and 
location. Here, we describe studies regarding the effects of noise on 
known marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick and Mann, 1999; Fay, 
2009). Depending on their hearing anatomy and peripheral sensory 
structures, which vary among species, fishes hear sounds using pressure 
and particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds that are especially strong and/or intermittent 
low-frequency sounds, and behavioral responses such as flight or 
avoidance are the most likely effects. Short duration, sharp sounds can 
cause overt or subtle changes in fish behavior and local distribution. 
The reaction of fish to noise depends on the physiological state of the 
fish, past exposures, motivation (e.g., feeding, spawning, migration), 
and other environmental factors. Hastings and Popper (2005) identified 
several studies that suggest fish may relocate to avoid certain areas 
of sound energy. Additional studies have documented effects of pile 
driving on fish; several are based on studies in support of large, 
multiyear bridge construction projects (e.g., Scholik and Yan, 2001; 
Scholik and Yan, 2002; Popper and Hastings, 2009). Several studies have 
demonstrated that impulse sounds might affect the distribution and 
behavior of some fishes, potentially impacting foraging opportunities 
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012; 
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; 
Paxton et al., 2017). However, some studies have shown no or slight 
reaction to impulse sounds (e.g., Pena et al., 2013; Wardle et al., 
2001; Jorgenson and Gyselman, 2009).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4 to 6 dB was recoverable within 24 
hours for one species. Impacts would be most severe when the individual 
fish is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al., 2012b; Casper et al., 2013).
    The most likely impact to fishes from pile driving activities at 
the project area would be temporary behavioral avoidance of the area. 
The duration of fish avoidance of this area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution, and 
behavior is anticipated. In general, impacts to marine mammal prey 
species are expected to be minor and temporary due to the expected 
short daily duration of individual pile driving events and the 
relatively small areas being affected. It is also not expected that the 
industrial environment of the Navy installations provides important 
fish habitat or harbors significant amount of forage fish.
    The area likely impacted by the activities is relatively small 
compared to the available habitat in inland waters in the region. Any 
behavioral avoidance by fish of the disturbed area would still leave 
significantly large areas of fish and marine mammal foraging habitat in 
the nearby vicinity. As described in the preceding, the potential for 
Navy construction to affect the availability of prey to marine mammals 
or to meaningfully impact the quality of physical or acoustic habitat 
is considered to be insignificant. Effects to habitat will not be 
discussed further in this document.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through the 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 would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., impact and vibratory pile driving and 
removal and DTH drilling) 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 
mid-frequency cetacean species and/or otariids, and they can be 
difficult to detect. Auditory injury is unlikely to occur for mid, low, 
and high-frequency cetacean species and otariids. The proposed 
mitigation and monitoring measures are expected to minimize the 
severity of the taking to the extent practicable.
    As described previously, no serious injury or mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the proposed take numbers are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the proposed take estimates.

[[Page 25595]]

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--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 (c) of 120 dB (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 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 Navy's proposed activity includes the use of continuous 
(vibratory pile driving and removal and DTH drilling) and impulsive 
(impact pile driving and DTH drilling) sources, and therefore the RMS 
SPL thresholds of 120 and 160 dB re 1 [mu]Pa is applicable, 
respectively.
    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 Navy's 
proposed activity includes the use of impulsive (impact pile driving 
and DTH drilling) and non-impulsive (vibratory pile driving and 
removal) 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: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 5--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 [mu]Pa, and SELcum (LE) has a reference value of
  1[micro]Pa\2\s. In this table, thresholds are abbreviated to reflect ANSI 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 SELcum
  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 SELcum thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss (TL) 
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., pile driving and removal and 
DTH drilling).
    The project includes vibratory pile installation and removal, 
impact pile driving, and DTH drilling in year 1 and vibratory pile 
installation and removal and impact pile driving in year 2. Source 
levels for these activities are based on reviews of measurements of the 
same or similar types and dimensions of piles available in the 
literature. Source levels for each pile size and activity each year are 
presented in table 6. Source levels for vibratory installation and 
removal of piles of the same diameter are assumed to be the same.
    NMFS recommends treating DTH systems as both impulsive and 
continuous, non-impulsive sound source type simultaneously. Thus, 
impulsive thresholds are used to evaluate Level A harassment, and 
continuous thresholds are used to evaluate Level B harassment. With 
regards to DTH mono-hammers, NMFS recommends proxy levels for Level A 
harassment based on available data

[[Page 25596]]

regarding DTH systems of similar sized piles and holes (Heyvaert and 
Reyff, 2021) (table 1, table 7 and table 8 includes number of piles and 
duration each year; table 6 includes sound pressure and sound exposure 
levels for each pile type).
    The Navy proposed to use bubble curtains when impact driving steel 
piles (relevant to Year 2 activities only). For the reasons described 
in the next paragraph, we assume here that use of the bubble curtain 
would result in a reduction of 8 dB from the assumed SPL (rms) and SPL 
(peak) source levels for these pile sizes, and reduce the applied 
source levels accordingly.
    During the 2023 study at NBK Bremerton, the Navy conducted 
comparative measurements of source levels when impact driving steel 
piles with and without a bubble curtain. Underwater sound levels were 
measured at two locations during the installation of one 24-in diameter 
steel pile and four 36-in steel piles. The bubble curtain used during 
the measurements reduced median peak sound levels by between 8 and 12 
dB, median RMS sound levels by 10 and 12 dB, and median single strike 
SEL sound levels by 7 and 8 dB. The analysis included in the proposed 
rule for the regulations preceding these IHAs (83 FR 9366, March 5, 
2018) as well as results from the NBK Bangor Trident Support Facilities 
Explosive Handling Wharf study (Navy 2013), are consistent with these 
findings. While proper set-up and operation of the system is critical, 
and variability in performance should be expected, we believe that in 
the circumstances evaluated here an effective attenuation performance 
of 8 dB is a reasonable assumption.

Table 6--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation, DTH Drilling, and Vibratory Pile Removal for
                                                                    Year 1 and Year 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
       Pile driving method             Pile type          Pile size        dB RMS      dB Peak       dB SEL         Attenuation            Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Year 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact..........................  Concrete..........  18-in...........          170          184          159  N/A..................  Navy 2015.
                                                      24-in...........          174          188          164  N/A..................  Navy 2015.
Vibratory.......................  Timber............  13-in...........          161          N/A          N/A  N/A..................  Greenbusch Group,
                                                                                                                                       Inc. 2019.
DTH.............................  Concrete..........  24-in...........          167          184          159  N/A..................  Heyvaert & Reyff
                                                                                                                                       2021.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Year 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact..........................  Steel \1\.........  12..............          177          192          167  -8 dB \1\............  Caltrans 2015,
                                                      36..............          194          211          181  -8 dB \1\............   2020.
                                                                                                                                      Navy 2015b.
Vibratory.......................                      12..............          153          N/A          N/A  N/A..................  Navy 2015b.
                                                      24..............          161          N/A          N/A  N/A..................  Navy 2015b.
                                                      36..............          166          N/A          N/A  N/A..................  Navy 2015b.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: dB peak = peak sound level; DTH = down-the-hole drilling; rms = root mean square; SEL = sound exposure level.
\1\ Values modeled for impact driving of 12-inch and 36-inch steel piles will be reduced by 8 dB for noise exposure modeling to account for attenuation
  from a bubble curtain

    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
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement

    Absent site-specific acoustical monitoring with differing measured 
TL, a practical spreading value of 15 is used as the TL coefficient in 
the above formula. Site-specific TL data for the Puget Sound are not 
available; therefore, the default coefficient of 15 is used to 
determine the distances to the Level A harassment and Level B 
harassment thresholds.
    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 overestimates of 
some degree, which may result in an overestimate of potential take by 
Level A harassment. However, this optional tool offers the best way to 
estimate isopleth distances when more sophisticated modeling methods 
are not available or practical. For stationary sources such as pile 
driving, the optional User Spreadsheet tool predicts the distance at 
which, if a marine mammal remained at that distance for the duration of 
the activity, it would be expected to incur PTS. Inputs used in the 
optional User Spreadsheet tool, and the resulting estimated isopleths, 
are reported below.

                                                        Table 7--User Spreadsheet Inputs, Year 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                           Vibratory                                          Impact                                        DTH
                              --------------------------------------------------------------------------------------------------------------------------
                                          13-in Timber                    18-in Concrete                  24-in Concrete              24-in Concrete
                              --------------------------------------------------------------------------------------------------------------------------
                                    Installation or removal                Installation                    Installation                Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used.........  A.1) Vibratory Pile Driving......  E.1) Impact Pile Driving......  E.1) Impact Pile Driving......  E.2) DTH Drilling.
Source Level (SPL)...........  161 RMS..........................  159 SEL.......................  164 SEL.......................  167 RMS, 159 SEL.
Transmission Loss Coefficient  15...............................  15............................  15............................  15.

[[Page 25597]]

 
Weighting Factor Adjustment    2.5..............................  2.............................  2.............................  2.
 (kHz).
Activity Duration per day      90...............................  ..............................  ..............................  80.
 (minutes).
Strike Rate per second.......  .................................  ..............................  ..............................  12.
Number of strikes per pile...  .................................  1,000.........................  1,000.........................
Number of piles per day......  6................................  5.............................  4.............................  2.
Distance of sound pressure     10...............................  10............................  10............................  10.
 level measurement.
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                                                            Table 8--User Spreadsheet Inputs, Year 2
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Vibratory                                                                         Impact
                               -----------------------------------------------------------------------------------------------------------------------------------------------------------------
                                           12-in Steel                       24-in Steel                       36-in Steel                   12-in Steel; BC               36-in Steel; BC
                               -----------------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Installation or removal           Installation or removal           Installation or removal              Installation                  Installation
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used..........  A.1) Vibratory Pile Driving.....  A.1) Vibratory Pile Driving.....  A.1) Vibratory Pile Driving.....  E.1) Impact Pile Driving....  E.1) Impact Pile Driving.
Source Level (SPL)............  153 RMS.........................  161 RMS.........................  166 RMS.........................  167 SEL.....................  181 SEL.
Transmission Loss Coefficient.  15..............................  15..............................  15..............................  15..........................  15.
Weighting Factor Adjustment     2.5.............................  2.5.............................  2.5.............................  2...........................  2.
 (kHz).
Activity Duration per day       30..............................  90..............................  133.............................  N/A.........................  N/A.
 (minutes).
Number of strikes per pile....  N/A.............................  N/A.............................  N/A.............................  1,000.......................  1,000.
Number of piles per day.......  2...............................  6...............................  4...............................  2...........................  4.
Distance of sound pressure      10..............................  10..............................  10..............................  10..........................  10.
 level measurement.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
BC = Bubble Curtain


   Table 9--Level A Harassment and Level B Harassment Isopleths From Vibratory and Impact Pile Driving and DTH
                                                    drilling
----------------------------------------------------------------------------------------------------------------
                                        Level A harassment isopleths (m)         Level B
                                 ---------------------------------------------  harassment   Area of harassment
            Pile type                                                            isopleth       zone (km\2\)
                                     LF       MF       HF       PW       OW        (m)
----------------------------------------------------------------------------------------------------------------
                                                     Year 1
                                                    Vibratory
----------------------------------------------------------------------------------------------------------------
13-inch timber..................      8.9       <1     13.2      5.4       <1        5,412  16 km\2\.
----------------------------------------------------------------------------------------------------------------
                                                     Impact
----------------------------------------------------------------------------------------------------------------
18-inch concrete................     73.3      2.6     87.4     39.3      2.9           46  0.007 km\2\.
24-inch concrete................    136.2      4.8    162.2     72.9      5.3           86  0.02 km\2\.
----------------------------------------------------------------------------------------------------------------
                                                       DTH
----------------------------------------------------------------------------------------------------------------
24-inch concrete................    374.1     13.3    445.6    200.2     14.6       13,594  75 km\2\.
----------------------------------------------------------------------------------------------------------------
                                                     Year 2
                                                    Vibratory
----------------------------------------------------------------------------------------------------------------
12-inch steel...................      1.3       <1       <1       <1       <1        1,585  8 km\2\.
24-inch steel...................      8.9       <1     13.2      5.4       <1        5,412  16 km\2\.
36-inch steel...................     25.1      2.2     37.0     15.2      1.1       11,659  31 km\2\.
----------------------------------------------------------------------------------------------------------------
                                                     Impact
----------------------------------------------------------------------------------------------------------------
12-inch steel...................     39.8      1.4     47.4     21.3      1.6         39.8  0.005 km\2\.

[[Page 25598]]

 
36-inch steel...................    542.1     19.3    645.8    290.1     21.1        541.2  0.92 km\2\.
----------------------------------------------------------------------------------------------------------------

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.
    Available information regarding marine mammal occurrence in the 
vicinity of the four installations includes density information 
aggregated in the Navy's Marine Mammal Species Density Database (NMSDD; 
Navy, 2019) or site-specific survey information from particular 
installations (e.g., local pinniped counts). More recent density 
estimates for harbor porpoise are available in Smultea et al. (2017) 
and Rone et al., (2024). First, for each installation we describe 
anticipated frequency of occurrence and the information deemed most 
appropriate for the exposure estimates. For all facilities, large 
whales (humpback whale, minke whale, and gray whale), killer whales 
(transient and resident), Dall's porpoise, and elephant seal are 
considered as occurring only rarely and unpredictably, on the basis of 
past sighting records. For these species, average group size is 
considered in concert with expected frequency of occurrence to develop 
the most realistic exposure estimate. Although certain species are not 
expected to occur at all at some facilities--for example, resident 
killer whales are not expected to occur in Hood Canal--the Navy has 
developed an overall take estimate and request for these species for 
each project year.
    All species described above are considered as rare, unpredictably 
occurring species. A density-based analysis is used for harbor porpoise 
(table 10), while data from site-specific abundance surveys are used 
for California sea lion, Steller sea lion, and harbor seal at all 
installations. One exception is that for Steller sea lion at NBK 
Bremerton, a density-based analysis is used because local data have 
resulted in no observations of this species (Navy, 2023).

                                        Table 10--Marine Mammal Densities
----------------------------------------------------------------------------------------------------------------
                                                                                                 Density (June-
                    Species                                         Region                         February)
----------------------------------------------------------------------------------------------------------------
Harbor porpoise................................  Hood Canal (Bangor).........................           \1\ 0.81
                                                 East Whidbey Island (Everett)...............           \2\ 0.75
                                                 Sinclair Inlet (Bremerton)..................           \2\ 0.53
                                                 Vashon (Manchester).........................           \2\ 0.25
Steller Sea Lion...............................  Puget Sound--Fall/Winter....................           \3\ 0.05
----------------------------------------------------------------------------------------------------------------
Sources: \1\ Rone et al., 2024; \2\ Smultea et al., 2017; \3\ Navy, 2019.

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 proposed for authorization.
    To quantitatively assess exposure of marine mammals to noise from 
pile driving activities, the Navy proposed three methods, to be used 
depending on the species' assumed spatial and temporal occurrence. For 
species with rare or infrequent occurrence at a given installation 
during the in-water work window, the likelihood of interaction was 
reviewed on the basis of past records of occurrence (described in 
Description of Marine Mammals in the Area of Specified Activities) and 
the potential maximum duration of work days at each installation, as 
well as total work days for all installations. Occurrence of the 
species in this category [i.e., large whales, killer whales, elephant 
seal (all installations), and Dall's porpoise (Hood Canal only)] would 
not be anticipated to extend for multiple days. Except for SRKW, the 
probable duration of all rare, unpredictably occurring species is 
assumed to be two days, roughly equivalent to one transit in and out of 
a project site. In the case of SRKW, the probable duration is assumed 
to be one day only, as SRKW have not been observed near naval 
installations during work completed previously at these installations. 
The calculation for species with rare or infrequent occurrence is:

Exposure estimate = expected group size x probable duration

    For species that occur regularly but for which site-specific 
abundance information is not available, density estimates (table 10) 
were used to determine the number of animals potentially exposed on any 
one day of pile driving or removal. The calculation for density-based 
analysis of species with regular occurrence is:

Exposure estimate = N (density) x Zone of Influence (ZOI, area) x days 
of pile driving

    For remaining species, site-specific abundance information (i.e., 
primarily the mean of monthly average counts per surveys completed 
between 2008 and 2022) was used. In cases where documented presence of 
a given pinniped species was variable throughout year and the mean of 
monthly average count (2008-2022) was [gteqt]1, the mean of monthly 
maximum counts of surveys completed between 2008 and 2022 was used:

Exposure estimate = Abundance x days of pile driving

    Large Whales--For each species of large whale (i.e., humpback 
whale, minke whale, and gray whale), we assume rare and infrequent 
occurrence at all installations. For all three species, if observed, 
they typically occur singly or in pairs. Therefore, for all three 
species, we assume that a pair of whales may occur in the vicinity of 
an

[[Page 25599]]

installation for a total of two days. We do not expect that this would 
happen multiple times, and cannot predict where such an occurrence may 
happen, so propose to authorize take by Level B harassment of four of 
each large whale species each project year.
    It is important to note that the Navy proposes to implement a 
shutdown of pile driving activity if any large whale is observed within 
any defined harassment zone (see Proposed Mitigation). Therefore, the 
proposed IHA is intended to provide insurance against the event that 
whales occur within Level B harassment zones that cannot be fully 
observed by monitors. As a result of this proposed mitigation, we do 
not believe that Level A harassment is a likely outcome upon occurrence 
of any large whale. The calculated Level A harassment zone is a maximum 
of 374 m for DTH installation of 24-in concrete piles in year 1 and 542 
m for impact installation of 36-in steel piles with a bubble curtain in 
year, and this requires that a whale be present at that range for the 
full duration of 1,000 pile strikes. Given the Navy's commitment to 
shut down upon observation of a large whale in any harassment zone, and 
the likelihood that the presence of a large whale in the vicinity of 
any Navy installation would be known due to reporting via Orca Network, 
we do not expect that any whale would be present within a Level A 
harassment zone for sufficient duration to actually experience PTS.
    Killer Whales--For transient killer whales, the proposed take 
authorization is derived via the same process described above for large 
whales: we assume an average group size of six whales occurring for a 
period of 2 days. The resulting total proposed authorization of take by 
Level B harassment of 12 for transient killer whales would also account 
for the low probability that a larger group occurred once. For SRKW, we 
assume an average group size of 20 whales occurring within the Level B 
harassment zone on one day each year. A group of 20 SRKW closely 
represents the average size of the pod most likely to occur near a Navy 
installation (the J pod), and corresponds to 75 percent of the average 
of all 3 pods that make up the stock. SRKW have not been observed near 
naval installations during work completed previously at these 
installations.
    Similar to large whales, the Navy plans to implement shutdown of 
pile driving activity at any time that any killer whale is observed 
within any calculated harassment zone. We expect this to minimize the 
extent and duration of any behavioral harassment. Given the small size 
of calculated Level A harassment zones--maximum of 13 m for DTH in year 
1, and 20 m for the worst-case scenario of impact-driven 36-in steel 
piles with a bubble curtain--we do not anticipate any potential for 
Level A harassment of killer whales.
    Dall's Porpoise--We assume rare and infrequent occurrence of Dall's 
porpoise at all installations. If observed, they typically occur in 
groups of five (Smultea et al., 2017). Therefore, we assume that a 
group of Dall's porpoise may occur in the vicinity of an installation 
for a total of two days. We do not expect that this would happen 
multiple times, and cannot predict where such an occurrence may happen, 
so conservatively propose to authorize take by Level B harassment of a 
total of 10 Dall's porpoise each project year.
    The Navy plans to implement shutdown of pile driving activity at 
any time if a Dall's porpoise is observed in the Level A harassment 
zone. The calculated Level A harassment zone is as large as 445 m for 
DTH of 24-in concrete in year 1 and as large as 646 m for impact 
driving of 36-in steel piles with a bubble curtain in year 2. Take by 
level A harassment would require that a porpoise be present at that 
range for the full duration of 1,000 pile strikes. Given the rarity of 
Dall's porpoise in the area, the Navy's commitment to shut down upon 
observation of a porpoise within the Level A harassment zone, and the 
likelihood that a porpoise would engage in aversive behavior prior to 
experiencing PTS, we do not expect that any porpoise would be present 
within a Level A harassment zone for sufficient duration to actually 
experience PTS.
    Harbor Porpoise--Level B exposure estimates for harbor porpoise 
were calculated for each installation each year using the appropriate 
density given in table 10, the largest appropriate ZOI for each pile 
type, and the appropriate number of construction days.
     NBK Bangor: Pile driving is not planned at this 
installation in year 1. For year 2, using the Hood Canal sub-region 
density, 36 days of pile driving in year 2, and the largest ZOIs 
calculated for each pile type at this location (31 km\2\ for vibratory 
installation of 36-in steel piles) produces an estimate of 905 
incidents of Level B harassment for harbor porpoise.
     NBK Bremerton: In year 1, using the Sinclair Inlet sub-
region density, 31 days of pile driving, and the largest ZOI calculated 
for each pile type at this location (16 km\2\ for removal and 
installation of 13-in timber piles, 0.2 km for impact installation of 
24-in concrete piles, and 0.07 km for impact installation of 18-in 
concrete) produces an estimate of 93 incidents of Level B harassment 
for harbor porpoise. In year 2, using the Sinclair Inlet sub-region 
density, 24 days of pile driving, and the largest ZOI calculated for 
each pile type at this location (16 km\2\ for vibratory removal and 
installation of 24-in steel piles) produces an estimate of 204 
incidents of Level B harassment for harbor porpoise.
     NBK Manchester: In year 1, using the Vashon sub-region 
density, 37 days of pile driving, and the largest ZOI calculated for 
each pile type at this location (75.8 km\2\ for DTH of 24-in concrete 
piles) produces an estimate of 701 incidents of Level B harassment for 
harbor porpoise. There are no pile driving activities planned at this 
installation in year 2.
     NS Everett: There are no pile driving activities planned 
at this installation in year 1. In year 2, using the East Whidbey sub-
region density, 8 days of pile driving, and the largest ZOI calculated 
each pile type at this location (8 km\2\) produces an estimate of 24 
incidents of Level B harassment for harbor porpoise.
    The Navy plans to implement shutdown of pile driving activity at 
any time if a harbor porpoise is observed in the Level A harassment 
zone. As a result of this proposed mitigation, we do not believe that 
Level A harassment is a likely outcome. There are two instances where 
the Level A harassment zone may extend beyond a distance where harbor 
porpoise may reliably be detected by PSOs. In Year 1, the Level A 
harassment zone is 445 m during DTH drilling of 24-in concrete at NBK 
Manchester. In Year 2, the Level A harassment zone is 645 m during 
impact driving of 36-in steel piles with a bubble curtain at NBK 
Bangor. However, Rone et al. (2024) reported a notable absence of 
harbor porpoise within 21 km\2\ in front of NBK Bangor. In both cases, 
harbor porpoise are uncommon in the area. Given the Navy's commitment 
to shut down upon observation of a porpoise within the Level A 
harassment zone, and the likelihood that a porpoise would engage in 
aversive behavior prior to experiencing PTS, we do not expect that any 
porpoise would be present within a Level A harassment zone for 
sufficient duration to actually experience PTS.
    Across all installations, we propose to authorize 794 takes by 
Level B harassment of harbor porpoise in year 1 and 1,157 takes by 
Level B harassment of harbor porpoise in year 2.
    Steller Sea Lion--Level B harassment estimates for Steller sea 
lions were calculated for each installation using the appropriate 
density given in table 10 or

[[Page 25600]]

site-specific abundance, the largest appropriate ZOI for each pile type 
at each installation, and the appropriate number of days. Please see 
Marine Mammal Monitoring Report at Navy Region Northwest Installations: 
2008-2022 (https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities) for 
details of site-specific abundance information (Navy, 2023).
     NBK Bangor: Steller sea lions are routinely seen hauled 
out from mid-September through May, with a maximum daily haul-out count 
of 21 individuals in November (based on data collected between 2008 and 
2022). Because the mean of monthly average counts per surveys between 
2008-2022 was 1, we relied the average of the maximum count of hauled 
out Steller sea lions for each month in the in-water work window (July-
January). The average of the monthly maximum counts during the in-water 
work window provides an estimate of 7.25 sea lions present per day. 
Using this value for 36 days in year 2 results in an estimate of 261 
incidents of Level B harassment in year 2. There are no pile driving 
activities planned at this installation in year 1.
     NBK Bremerton: Steller sea lions have been documented only 
twice at this installation between 2008 and 2022. As such density 
values were used to estimate take at this location. Using the Puget 
Sound density value for fall-winter, 31 days of pile driving in year 1, 
and the largest ZOI calculated for each pile type at this location (16 
km\2\ for removal and installation of 13-in timber piles, 0.2 km for 
impact installation of 24-in concrete piles, and 0.07 km for impact 
installation of 18-in concrete) produces an estimate of 9 incidents of 
Level B harassment for Steller sea lion in year 1. Using the Puget 
Sound density value for fall-winter, 24 days of pile driving in year 2, 
and the largest ZOI calculated for each pile type at this location (16 
km\2\ for vibratory removal and installation of 24-in steel piles) 
produces an estimate of 18 incidents of Level B harassment for Steller 
sea lion in year 2.
     NBK Manchester: Steller sea lions are observed 
periodically at NBK Manchester since surveys began in 2012. We estimate 
take based on the monthly mean counts per surveys conducted from July 
to February, between 2012 and 2022, which provides an estimate of six 
Steller sea lions per day. In year 1, using this value for 37 days in 
results in an estimate of 222 incidents of Level B harassment. There 
are no pile driving activities planned at this installation in year 2.
     NS Everett: Steller sea lions were rarely observed at NS 
Everett between 2012 and 2022. All observations were of lone 
individuals hauled out on a PSB or in a nearby basin. We conservatively 
estimate that one Steller sea lion could occur within the project area 
per day. Using this value for 8 days in year 2 results in an estimate 
of 8 incidents of Level B harassment in year 2. There are no pile 
driving activities planned at this installation in year 1.
    Given the small size of calculated Level A harassment zones--
maximum of 15 m for the worst-case scenario of DTH-installed 24-in 
concrete piles in year 1 and maximum of 21 m for the worst-case 
scenario of impact-driven 36-in steel piles with the use of a bubble 
curtain in year 2--we do not anticipate any potential for Level A 
harassment of Steller sea lions.
    Across all installations we propose to authorize take by 231 takes 
by Level B harassment of Steller sea lion in year 1 and 287 takes by 
Level B harassment of Steller sea lions in year 2.
    California Sea Lion--Level B harassment estimates for California 
sea lions were calculated for each installation using the appropriate 
site-specific abundance, the largest appropriate ZOI for each pile type 
at each installation, and the appropriate number of days. Please see 
Marine Mammal Monitoring Report at Navy Region Northwest Installations: 
2008-2022 (https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities) for 
details of site-specific abundance information (Navy, 2023).
     NBK Bangor: California sea lions haul out in all months on 
floating PSB and on submarines docked at Delta Pier, with lower numbers 
in June through July. We estimate take based on the monthly mean counts 
per surveys conducted from July to January, between 2012 and 2022, 
which provides an estimate of 25 California sea lions per day. In year 
2, using this value for 36 days results in an estimate of 900 incidents 
of Level B harassment in year 2. There are no pile driving activities 
planned at this installation in year 1.
     NBK Bremerton: California sea lions are routinely seen 
hauled out on floats at NBK Bremerton during most of the year. We 
estimate take based on the monthly mean count per surveys conducted 
from July through February, between 2010 and 2022, which provides an 
estimate of 98 California sea lions per day. In year 1, using this 
value for 31 days generates an estimate of 3,038 incidents of Level B 
harassment. In year 2, using this value for 24 days generates an 
estimate of 2,352 incidents of Level B harassment in year 2.
     NBK Manchester: California sea lions have been observed at 
this installation at least once each month of the year, with peak 
numbers occurring in October and November. Floats used as haulouts are 
periodically installed and removed, making numbers in the vicinity 
highly variable. We estimate take based on the monthly mean count per 
surveys conducted from July through February, between 2012 and 2022, 
which provides an estimate of 24 California sea lions per day. In year 
1, using this value for 37 days generates an estimate of 1,274 
incidents of Level B harassment. There are no pile driving activities 
planned at this installation in year 2.
     NS Everett: California sea lions have been observed every 
month of the year. We estimate take based on the monthly mean count per 
survey conducted from July through February between 2012 and 2022, 
which provides an estimate of 48 California sea lions per day. In year 
2, using this value for 8 days in year 2 generates an estimate of 384 
incidents of Level B exposures. There are no pile driving activities 
planned at this installation in year 1.
    Given the small size of calculated Level A harassment zones--
maximum of 15 m for the worst-case scenario of DTH-installed 24-in 
concrete piles in year 1 and maximum of 21 m for the worst-case 
scenario of impact-driven 36-in steel piles with the use of a bubble 
curtain in year 2--we do not anticipate any potential for Level A 
harassment of California sea lions.
    Across all installations we propose to authorize 3,926 takes by 
Level B harassment of California sea lions in year 1 and 3,636 takes by 
Level B harassment of California sea lions in year 2.
    Harbor Seal--Harbor seals are expected to occur year-round at all 
installations, with the greatest numbers expected at installations with 
nearby haul-out sites. Level B exposure estimates for harbor seals were 
calculated for each installation using the appropriate site-specific 
abundance, the largest appropriate ZOI for each pile type at each 
installation, and the appropriate number of days. Please see Marine 
Mammal Monitoring Report at Navy Region Northwest Installations: 2008-
2022 (https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities) for details of 
site-specific abundance information (Navy, 2023).

[[Page 25601]]

    Harbor seals are expected to be the most abundant marine mammal at 
all installations, often occurring in and around existing in-water 
structures in a way that may restrict observers' ability to adequately 
observe seals and subsequently implement shutdowns. In addition, the 
calculated Level A harassment zones are significantly larger than those 
for sea lions, which may also be abundant at various installations at 
certain times of year. For harbor seals in year 1, the largest 
calculated Level A harassment zone is 200 m (compared with a maximum 
zone of 15 m for sea lions), calculated for the worst-case scenario of 
DTH-installed 24-in concrete piles (other scenarios range from 5-75 m). 
In year 2, the largest calculated Level A harassment zone is 290 m 
(compared with a maximum zone of 21 m for sea lions), calculated for 
the worst-case scenario of impact-driven 36-in steel piles with the use 
of a bubble curtain (other scenarios range from 1-21 m). Therefore, we 
assume that some Level A harassment is likely to occur for harbor seals 
and provide installation-specific estimates below.
     NBK Bangor: Harbor seals are year-round residents at NBK 
Bangor and have been identified at least once during each calendar 
month over several survey years. They have been observed swimming and 
hauled out on man-made structures including docks, catwalks under the 
dock at Marginal Pier, PSBs, and boats along the NBK Bangor waterfront, 
The Navy plans to place fencing around the catwalks at Marginal Pier, 
which may reduce harbor seal haulout opportunities at NBK Bangor. 
Because the mean of monthly average counts per surveys between 2008-
2022 was <1, we estimate take by Level B harassment based on the mean 
maximum count per month of surveys conducted from July to January, 
between 2008 and 2022, which provides an estimate of 16 harbor seals 
per day. In year 2, using this value for 36 days results in an estimate 
of 576 incidents of Level B exposures. There are no pile driving 
activities planned at this installation in year 1.
    The Level A harassment zone expected to occur during impact 
installation of 36-in steel at NBK Bangor is 290 m. Since the Navy 
plans to maintain a shutdown zone of at 180 m (see table 13), the Navy 
estimates and NMFS agrees that one seal per day (n = 20) could remain 
within the calculated Level A harassment zone for a sufficient period 
to accumulate enough energy to result in PTS. As such, we propose to 
authorize 20 incidents of take by Level A harassment.
     NBK Bremerton: Observations of harbor seals are 
intermittent at NBK Bremerton. They are primarily observed swimming in 
the water around piers and structures and less frequently hauled out on 
floats and docked submarines. Because the mean of monthly average 
counts per surveys between 2008-2022 was <1, we estimate take based on 
the mean maximum count per month of surveys from July to February, 
between 2010 and 2022, which provides an estimate of two harbor seals 
per day. In year 1, using this value for 31 days results in an estimate 
of 62 incidents of Level B exposures. In year 2, using this value for 
24 days results in an estimate of 48 incidents of Level B harassment.
    In year 1, the Level A harassment zone expected to occur during 
impact installation of 18-in steel at NBK Bremerton is 39 m and the 
Level A harassment zone expected to occur during impact installation of 
24-in steel is 73 m. Although the Navy plans to shut down at distances 
slightly larger than these Level A harassment zones (see table 12), the 
Navy assumes and NMFS agrees that it is possible that one seal per day 
could go unobserved and remain within the calculated zone for a 
sufficient period to accumulate enough energy to result in PTS. As 
such, we propose to authorize 20 takes by Level A harassment. In year 
2, the largest Level A harassment zone is much smaller (<10 m) and as 
such we do not expect take by Level A harassment to occur and we do not 
propose to authorize such take.
     NBK Manchester: No harbor seal haulouts have been 
identified at NBK Manchester, but seals regularly haul out at Orchard 
Rocks and are observed swimming through the project area. We estimate 
take based on the monthly mean count per survey conducted from July 
through February between 2020 and 2022 (Orchard Rocks was incorporated 
into surveys in 2020), which provides an estimate of 10 harbor seals 
per day. In year 1, using this value for 37 days results in an estimate 
of 370 incidents of Level B harassment. There are no pile driving 
activities planned at this installation in year 2.
    The Level A harassment zone expected to occur during DTH 
installation of 24-in concrete at NBK Manchester is 200 m. Since the 
Navy plans to shut down at 150 m due to practicability concerns (see 
table 12), the Navy assumes and NMFS agrees that one seal per day (n = 
37) could remain within the calculated zone for a sufficient period to 
accumulate enough energy to result in PTS. As such, we propose to 
authorize 37 incidents of take by Level A harassment.
     NS Everett: Harbor seals haul out year round on floats, 
riprap, and human structures at NS Everett. We estimate take based on 
the monthly mean count per survey conducted from July through February 
between 2019 and 2022 (the east side of East Waterway was incorporated 
into surveys in 2019), which provides an estimate of 266 harbor seals 
per day. In year 2, using this value for 8 days results in an estimate 
of 2,128 incidents of Level B harassment. There are no planned pile 
driving activities at this installation in year 1.
    The largest Level A harassment zone expected to occur at NS Everett 
is 21 m and the Navy plans to shut down at this distance should a 
harbor seal be observed entering or within this zone. As such we do not 
expect take by Level A harassment to occur and we do not propose to 
authorize such take here.
    Any individuals exposed to the higher levels associated with the 
potential for PTS closer to the source might also be behaviorally 
disturbed, however, for the purposes of quantifying take we do not 
count those exposures of one individual as both a Level A harassment 
take and a Level B harassment take, and therefore takes by Level B 
harassment calculated as described above are further modified to deduct 
the proposed amount of take by Level A harassment. Therefore, in year 
1, across all installations, NMFS proposes to authorize 57 takes by 
Level A harassment and 432 takes by Level B harassment for harbor seal, 
for a total of 489 takes. In year 2, across all installations, NMFS 
proposes to authorize 20 takes by Level A harassment and 2,752 takes by 
Level B harassment for harbor seal, for a total of 2,772 takes.
    Northern Elephant Seal--Northern elephant seals are considered rare 
visitors to Puget Sound. However, solitary juvenile elephant seals have 
been known to sporadically haul out to molt in Puget Sound during 
spring and summer months. Because there are occasional sightings in 
Puget Sound, the Navy reasons that exposure of up to one seal to noise 
above Level B harassment thresholds could occur for a two-day duration 
for a total of 2 takes by Level B harassment of northern elephant seals 
each year.
    The total proposed take authorization for all species each year is 
summarized in table 11 below. No authorization of take by Level A 
harassment is proposed for authorization except a total of 57 such 
incidents for harbor seals in year 1 and 20 such incidents for harbor 
seals in year 2.

[[Page 25602]]



                                               Table 11--Proposed Take Authorization by Level B Harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 Year 1                                        Year 2
                                                             -------------------------------------------------------------------------------------------
               Species                         Stock                                     Proposed take as                              Proposed take as
                                                                Level A      Level B      a percentage of     Level A      Level B      a percentage of
                                                               harassment   harassment    stock abundance    harassment   harassment    stock abundance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback Whale......................  CenAmer./S Mex-CA-OR-             0            0                   0            0            0                   0
                                       WA.
                                      Mex-CA-OR-WA..........                         1                  <1            0            1                  <1
                                      Hawai'i...............                         3                  <1            0            3                  <1
Minke Whale.........................  CA-OR-WA..............            0            4                  <1            0            4                  <1
Gray Whale..........................  Eastern N Pacific.....            0            4                  <1            0            4                  <1
Killer Whale........................  W Coast Transient.....            0           12                   3            0           12                   3
                                      E.N.P.--S Resident....            0           20                  27            0           20                  27
Harbor Porpoise.....................  WA. Inland............            0          794                   7            0        1,157                  10
Dall's Porpoise.....................  CA-OR-WA..............            0           10                  <1            0           10                  <1
Steller Sea Lion....................  Eastern US............            0          231                  <1            0          287                  <1
California Sea Lion.................  US....................            0        3,926                   2            0        3,636                 1.4
Northern Elephant Seal..............  CA Breeding...........            0            2                  <1            0            2                  <1
Harbor Seal.........................  WA N Inland...........           57          375                   4            0         2176                  13
                                      Hood Canal............            0            0                   0           20          576                  17
--------------------------------------------------------------------------------------------------------------------------------------------------------

Proposed 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.
    Timing--As described previously, the Navy would adhere to in-water 
work windows designed for the protection of fish. These timing windows 
would also benefit marine mammals by limiting the annual duration of 
construction activities. At NBK Bangor, the Navy would adhere to a July 
16 through January 15 window, while at the remaining facilities this 
window is extended to February 15 each project year.
    On a daily basis, in-water construction activities would occur only 
during daylight hours (sunrise to sunset) except from July 16 to 
September 15, when impact pile driving would only occur starting 2 
hours after sunrise and ending 2 hours before sunset in order to 
protect marbled murrelets (Brachyramphus marmoratus) during the nesting 
season. The exception is NBK Bremerton, where marbled murrelets do not 
occur.
    Shutdown Zone--For all pile driving, removal, and DTH drilling, the 
Navy would implement shutdowns within designated zones. The purpose of 
a shutdown zone is generally to define an area within which shutdown of 
activity would occur upon sighting of a marine mammal (or in 
anticipation of an animal entering the defined area). For all pile 
driving activities, the Navy would establish a minimum shutdown zone 
with a radial distance of 10 m. This minimum zone is intended to 
prevent the already unlikely possibility of physical interaction with 
construction equipment and to establish a precautionary minimum zone 
with regard to acoustic effects. In most circumstances where the 
predicted Level A harassment zone exceeds the minimum zone, the Navy 
proposes to implement a shutdown zone greater or equal to the predicted 
Level A harassment zone (see tables 12 and 13). However, in cases where 
it would be challenging to detect marine mammals at the Level A 
harassment isopleth and frequent shutdowns would create practicability 
concerns (e.g., for phocids during DTH at NBK Manchester in year 1 and 
impact pile driving at NBK Bangor in year 2), smaller shutdown zones 
have been proposed. In addition, the Navy proposes to implement 
shutdown upon observation of any large whales and killer whales within 
a calculated Level B harassment zone. Recognizing that the entirety of 
the Level B harassment zone cannot practicably be monitored, the Orca 
Network would be consulted prior to commencing pile driving each day, 
and pile driving would also be delayed or shutdown if low-frequency or 
mid-frequency cetaceans are reported near or approaching the Level B 
harassment zone. In all cases, predicted injury zones are calculated on 
the basis of cumulative sound exposure, as peak pressure source levels 
produce smaller predicted zones.
    Finally, construction activities would be halted upon observation 
of 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 25603]]



                                                            Table 12--Shutdown Zones, Year 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                     Shutdown zones  (m)                          Level B      Level B
              Activity                     Pile size/type     -----------------------------------------------------------------  harassment   monitoring
                                                                    LF           MF           HF           PW           OW       zone  (m)    zone  (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Installation.................  18-in Concrete.........          100           50          100           40           10           46          N/A
                                      24-in Concrete.........          170           90          170           75           10           86          N/A
Vibratory Installation or Removal...  13-in Timber...........    \2\ 5,412    \2\ 5,412           15           10           10        5,412      \1\ 400
DTH.................................  24-in Concrete.........   \2\ 13,594   \2\ 13,594      \3\ 450          150           20       13,594      \1\ 450
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Observers must be able to monitor at minimum the Level B monitoring zone prior to commencing vibratory pile driving and removal and DTH drilling.
\2\ This shutdown zone likely extends beyond the distance that low- and mid-frequency cetaceans can be reliably detected. Observers will monitor this
  shutdown zone to the maximum extent possible based on the number and location of PSOs deployed and weather conditions.
\3\ This shutdown zone likely extends beyond the distance that harbor porpoise can be reliably detected. However, harbor porpoise are uncommon near NKB
  Manchester, and it is likely that they would engage in aversive behavior prior to experiencing PTS. As such, we do not expect that any porpoise would
  be present within a Level A harassment zone for sufficient duration to actually experience PTS.


                                                            Table 13--Shutdown Zones, Year 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                     Shutdown zones  (m)                          Level B      Level B
              Activity                     Pile size/type     -----------------------------------------------------------------  harassment   monitoring
                                                                    LF           MF           HF           PW           OW       zone  (m)    zone  (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Installation.................  12-in Steel............           50           50           50           30           10         39.8          N/A
                                      36-in Steel............          650          650      \3\ 650          180           25        541.2          N/A
Vibratory Installation or Removal...  12-in Steel............        1,585        1,585           10           10           10        1,585      \1\ 400
                                      24-in Steel............    \2\ 5,412    \2\ 5,412           15           10           10        5,412      \1\ 400
                                      36-in Steel............   \2\ 11,659   \2\ 11,659           40           20           10       11,659      \1\ 400
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Observers must be able to monitor at minimum the Level B monitoring zone prior to commencing vibratory pile driving and removal
\2\ This shutdown zone likely extends beyond the distance that low- and mid-frequency cetaceans can be reliably detected. Observers will monitor this
  shutdown zone to the maximum extent possible based on the number and location of deployed PSOs and weather conditions
\3\ This shutdown zone likely extends beyond the distance that harbor porpoise can be reliably detected. However, harbor porpoise were notably absent
  within 21 km\2\ in front of NKB Bangor (Rone et al., 2024) and it is likely that they would engage in aversive behavior prior to experiencing PTS. As
  such, we do not expect that any porpoise would be present within a Level A harassment zone for sufficient duration to actually experience PTS.

    Protected Species Observers--The number and placement of PSOs 
during all construction activities (described in the Proposed 
Monitoring and Reporting section) would ensure that the entire shutdown 
zone is visible, except in cases when the shutdown zone is based on the 
Level B harassment zone (large whales and killer whales). In such 
cases, PSOs must be able to monitor at minimum the Level A harassment 
zone. The Navy would employ at least three PSOs for all pile driving 
and DTH drilling.
    Monitoring for Level B Harassment--PSOs would monitor the shutdown 
zones and beyond to the extent that PSOs can see. Monitoring beyond the 
shutdown zones enables observers to be aware of and communicate the 
presence of marine mammals in the project areas outside the shutdown 
zones and thus prepare for a potential cessation of activity should the 
animal enter the shutdown zone. Additionally, prior to commencing pile 
driving, PSOs will contact Navy marine biologists or the Orca Network 
directly to obtain reports of large whales in the area.
    In order to document observed incidents of harassment, PSOs record 
all marine mammal observations, regardless of location. The PSO's 
location and the location of the pile being driven are known, and the 
location of the animal may be estimated as a distance from the observer 
and then compared to the location from the pile. It may then be 
estimated whether the animal was exposed to sound levels constituting 
incidental harassment on the basis of predicted distances to relevant 
thresholds in post-processing of observational data, and a precise 
accounting of observed incidents of harassment created.
    Pre and Post-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, Level A 
harassment zone, and Level B harassment zone (to the extent possible 
based on the number and location of PSOs and weather conditions) for a 
period of 30 minutes. Pre-start clearance monitoring must be conducted 
during periods of visibility sufficient for the lead PSO to determine 
that the shutdown zones and, during vibratory driving and removal and 
DTH drilling, the Level B monitoring zone, are clear of marine mammals, 
If these zones are obscured by fog or poor lighting conditions, in-
water construction activity will not be initiated until the entire 
shutdown zone is visible. Pile driving may commence following 30 
minutes of observation when the determination is made that the shutdown 
zones and, during vibratory driving and removal and DTH drilling, the 
Level B monitoring zone, are clear of marine mammals. If a marine 
mammal is observed entering or within these zones, pile driving 
activity must be delayed or halted. During vibratory driving and 
removal and DTH, the Navy will shut down upon any observation of large 
whales and killer whales. If pile driving is delayed or halted due to 
the presence of a marine mammal, the activity may not commence or 
resume until either the animal has voluntarily exited and been visually 
confirmed beyond the shutdown zone or 15 minutes have passed without 
re-detection of the animal.
    The Navy also plans to take measures to ensure that killer whales 
and large cetaceans (i.e., humpback whale, gray whale, and minke whale) 
are not located within the vicinity of the project area, including, but 
not limited to, contacting and/or reviewing the latest sightings data 
from the Orca Network and/or Center for Whale Research, including 
passive acoustic detections, to determine the location of the nearest 
marine mammal sightings.
    Soft Start--The use of a soft start procedure is believed to 
provide additional protection to marine mammals by warning marine 
mammals or providing them with a chance to leave the area prior to the 
hammer operating at full capacity. The Navy will utilize soft start 
techniques for impact pile driving. We require an initial set of three 
strikes from the impact hammer at reduced energy, followed by a 30-
second waiting period, then two subsequent three-strike sets. Soft 
start

[[Page 25604]]

will be required at the beginning of each day's impact pile driving 
work and at any time following a cessation of impact pile driving of 30 
minutes or longer; the requirement to implement soft start for impact 
driving is independent of whether vibratory driving has occurred within 
the prior 30 minutes. Soft start is not required during vibratory pile 
driving activities.
    Bubble Curtain--A bubble curtain would be used for all impact 
driving of steel piles to attenuate noise. A bubble curtain would be 
employed during impact installation or proofing of steel pile where 
water depths are greater than 2 ft (0.67 m). Bubble curtains are not 
proposed for installation of other pile types due to the relatively low 
source levels, as the requirement to deploy the curtain system at each 
driven pile results in a significantly lower production rate. Where a 
bubble curtain is used, the contractor would be required to turn it on 
prior to the soft start in order to flush fish from the area closest to 
the driven pile.
    To avoid loss of attenuation from design and implementation errors, 
the Navy will require specific bubble curtain design specifications, 
including testing requirements for air pressure and flow at each 
manifold ring prior to initial impact hammer use, and a requirement for 
placement on the substrate. The bubble curtain must distribute air 
bubbles around 100 percent of the piling perimeter for the full depth 
of the water column. The lowest bubble ring shall be in contact with 
the mudline for the full circumference of the ring, and the weights 
attached to the bottom ring shall ensure 100 percent mudline contact. 
No parts of the ring or other objects shall prevent full mudline 
contact. The contractor shall also train personnel in the proper 
balancing of air flow to the bubblers, and must submit an inspection/
performance report to the Navy for approval within 72 hours following 
the performance test. Corrections to the noise attenuation device to 
meet the performance standards shall occur prior to use for impact 
driving.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed 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.

Proposed 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 both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.
    Visual Monitoring--Marine mammal monitoring must be conducted in 
accordance with the Marine Mammal Monitoring and Mitigation Plan. 
Marine mammal monitoring during pile driving and removal and DTH 
drilling must be conducted by NMFS-approved PSOs in a manner consistent 
with the following:
     PSOs must be independent of the activity contractor (for 
example, employed by a subcontractor), and have no other assigned tasks 
during monitoring periods;
     At least one PSO must have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
incidental take authorization;
     Other PSOs may substitute other relevant experience, 
education (degree in biological science or related field) or training 
for experience performing the duties of a PSO during construction 
activities pursuant to a NMFS-issued incidental take authorization;
     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 activity pursuant to a NMFS-issued 
incidental take authorization; and
     PSOs must be approved by NMFS prior to beginning any 
activity subject to each IHA.
    PSOs should also 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 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 note 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.
    Visual monitoring will be conducted by a minimum of three trained 
PSOs positioned at suitable vantage points practicable (e.g., from a 
small boat, the pile driving barge, on shore, piers, or any other 
suitable location). One PSO will have an unobstructed view of all water 
within the shutdown zone, and during vibratory pile driving and removal 
and DTH drilling, the Level B monitoring zone. Remaining PSOs will 
observe as much as the Level A and Level B harassment zones as 
possible.

[[Page 25605]]

    Monitoring will be conducted 30 minutes before, during, and 30 
minutes after all in water construction activities. In addition, 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. 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 equipment is no more than 30 minutes.

Acoustic Monitoring

    The Navy plans to conduct hydroacoustic monitoring for a subset of 
impact-driven steel piles for projects including more than three piles 
where a bubble curtain is used (relevant to year 2 project activities 
only).

Reporting

    The Navy will submit a draft marine mammal monitoring report to 
NMFS within 90 days after the completion of pile driving activities, 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 data sheets. 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: (1) The number and type of piles that 
were driven and the method (e.g., impact or vibratory); and (2) Total 
duration of driving time for each pile (vibratory driving) and number 
of strikes for each pile (impact driving);
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: (1) Name of PSO who sighted the animal(s) and PSO location 
and activity at time of sighting; (2) Time of sighting; (3) 
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; (4) 
Distance and location of each observed marine mammal relative to the 
pile being driven for each sighting; (5) Estimated number of animals 
(min/max/best estimate); (6) Estimated number of animals by cohort 
(adults, juveniles, neonates, group composition, etc.); (7) Animal's 
closest point of approach and estimated time spent within the 
harassment zone; and (8) Description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses thought to have 
resulted from the activity (e.g., no response or changes in behavioral 
state such as ceasing feeding, changing direction, flushing, or 
breaching);
     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 specific 
actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    A final report must be prepared and submitted within 30 calendar 
days following receipt of any NMFS comments on the draft report. If no 
comments are received from NMFS within 30 calendar days of receipt of 
the draft report, the report will be considered final. All PSO data 
would be submitted electronically in a format that can be queried such 
as a spreadsheet or database and would 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 Holder must report the 
incident to the Office of Protected Resources (OPR), NMFS 
([email protected] and [email protected]) and the 
West Coast Regional Stranding Coordinator as soon as feasible. If the 
death or injury was clearly caused by the specified activity, the 
Holder 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 Holder must not resume their activities until notified 
by NMFS. The report must 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 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 majority of our analysis applies to all 
the species listed in table 3, given that many of the anticipated 
effects of this project on different marine mammal stocks are expected 
to be relatively similar in nature. Where there are meaningful 
differences between species or stocks, or groups of species, in 
anticipated individual responses to activities, impact of expected take 
on the population due to differences in population status, or impacts 
on habitat, they are described independently in the analysis below.

[[Page 25606]]

    Pile driving activities associated with the maintenance projects, 
as described previously, have the potential to disturb or displace 
marine mammals. Specifically, the specified activities may result in 
take, in the form of Level B harassment (behavioral disturbance) only 
(for all species other than harbor seal) from underwater sounds 
generated from pile driving. Potential takes could occur if individual 
marine mammals are present in the ensonified zone when pile driving is 
happening.
    No serious injury or mortality would be expected even in the 
absence of the proposed mitigation measures. For all species other than 
the harbor seal, no Level A harassment is anticipated given the nature 
of the activities, i.e., much of the anticipated activity would involve 
measures designed to minimize the possibility of injury. The potential 
for injury is small for cetaceans and sea lions, and is expected to be 
essentially eliminated through implementation of the proposed 
mitigation measures--use of the bubble curtain for steel piles 
(relevant to year 2 only), soft start (for impact driving), and 
shutdown zones. Impact driving, as compared with vibratory driving, has 
source characteristics (short, sharp pulses with higher peak levels and 
much sharper rise time to reach those peaks) that are potentially 
injurious or more likely to produce severe behavioral reactions. Given 
sufficient notice through use of soft start, marine mammals are 
expected to move away from a sound source that is annoying prior to 
becoming potentially injurious or resulting in more severe behavioral 
reactions. Additionally, environmental conditions in inland waters are 
expected to generally be good, with calm sea states, and we expect 
conditions would allow a high marine mammal detection capability, 
enabling a high rate of success in implementation of shutdowns to avoid 
injury.
    As described previously, there are multiple species that are 
considered rare in the proposed project areas and for which we propose 
to authorize limited take, by Level B harassment, of a single group for 
a minimal period of time in each authorization year (one or two days).
    ESA critical habitat for southern resident killer whale occurs in 
Puget Sound (see the Description of Marine Mammals in the Area of 
Specified Activities section of this notice). NMFS did not identify in-
water sound levels as a separate essential feature of critical habitat, 
though anthropogenic sound is recognized as one of the primary threats 
to SRKW (NMFS 2019). The exposure of SRKW to sound from the proposed 
activities would be minimized by the required proposed mitigation 
measures (e.g., shutdown zones equivalent to the Level B harassment 
zones). The effects of the activities on SRKW habitat generally, such 
as sedimentation and impacts to availability of prey species, are 
expected to be limited both spatially and temporally, constrained to 
the immediate area around the pile driver(s) at each pier and returning 
to baseline levels quickly. Additionally, the timing of the in-water 
work window for the projects is intended to limit impacts to ESA-listed 
fishes, which would accordingly reduce potential impacts to SRKW prey.
    Puget Sound is part of a BIA for migrating gray whales 
(Calambokidis et al., 2015). However, gray whales in this area 
typically remain further north, primarily in the waters around Whidbey 
Island (Calambokidis et al., 2018) (an area where only 8 days of pile 
driving are planned). Therefore, even though the project areas overlap 
with the BIA, the infrequent occurrence of gray whales suggests that 
the proposed projects would have minimal, if any, impact on the 
migration of gray whales, and would therefore not affect reproduction 
or survival.
    Aside from the SRKW critical habitat and BIA for gray whales, there 
are no known important areas for other marine mammals, such as feeding 
or pupping areas. Therefore, we do not expect meaningful impacts to 
these species (i.e., humpback whale, gray whale, minke whale, transient 
and resident killer whales, Dall's porpoise, and northern elephant 
seal) and preliminarily find, for both the proposed Year 1 and Year 2 
IHAs, that the total marine mammal take from the specified activities 
will have a negligible impact on these marine mammal species.
    For remaining species (harbor porpoise, California sea lion, 
Steller sea lion, and harbor seal), we discuss the likely effects of 
the specified activities in greater detail. Effects on individuals that 
are taken by Level B harassment, on the basis of reports in the 
literature as well as monitoring from other similar activities, will 
likely be limited to reactions such as increased swimming speeds, 
increased surfacing time, or decreased foraging (if such activity were 
occurring) (e.g., Thorson and Reyff, 2006; HDR, Inc., 2012; Lerma, 
2014). Most likely, individuals will simply move away from the sound 
source and be temporarily displaced from the areas of pile driving, 
although even this reaction has been observed primarily only in 
association with impact pile driving.
    The Navy has conducted multi-year activities potentially affecting 
marine mammals, and typically involving greater or similar levels of 
activity than is contemplated here in various locations such as San 
Diego Bay and some of the installations considered herein (NBK Bangor, 
NBK Bremerton, NBK Manchester). Reporting from these activities has 
similarly reported no apparently consequential behavioral reactions or 
long-term effects on marine mammal populations (Lerma, 2014; Navy, 
2016; Sandoval et al., 2022; Sandoval and Johnson, 2022; Hamer 
Environmental 2021; DoN, 2021 and 2022). Repeated exposures of 
individuals to relatively low levels of sound outside of preferred 
habitat areas are unlikely to significantly disrupt critical behaviors. 
Thus, even repeated Level B harassment of some small subset of the 
overall stock is unlikely to result in any significant realized 
decrease in viability for the affected individuals, and thus would not 
result in any adverse impact to the stock as a whole. Level B 
harassment will be reduced to the level of least practicable adverse 
impact through use of mitigation measures described herein and, if 
sound produced by project activities is sufficiently disturbing, 
animals are likely to simply avoid the area while the activity is 
occurring. While vibratory driving and DTH drilling associated with 
some project components may produce sound at distances of many kms from 
the pile driving site, thus intruding on higher-quality habitat, the 
project sites themselves and the majority of sound fields produced by 
the specified activities are within industrialized areas. Therefore, we 
expect that animals annoyed by project sound would simply avoid the 
area and use more-preferred habitats.
    In addition to the expected effects resulting from authorized Level 
B harassment, we anticipate that harbor seals may sustain some limited 
Level A harassment in the form of auditory injury at two installations 
in year 1 (NBK Bremerton and NBK Manchester) and one installation in 
year 2 (NBK Bangor), assuming they remain within a given distance of 
the pile driving activity for the full number of pile strikes. However, 
seals in these locations that experience PTS would likely only receive 
slight PTS, i.e., minor degradation of hearing capabilities within 
regions of hearing that align most completely with the energy produced 
by pile driving, i.e., the low-frequency region below 2 kHz, not severe 
hearing impairment or

[[Page 25607]]

impairment in the regions of greatest hearing sensitivity. If hearing 
impairment occurs, it is most likely that the affected animal would 
lose a few decibels in its hearing sensitivity, which in most cases is 
not likely to meaningfully affect its ability to forage and communicate 
with conspecifics. As described above, we expect that marine mammals 
would be likely to move away from a sound source that represents an 
aversive stimulus, especially at levels that would be expected to 
result in PTS, given sufficient notice through use of soft start.
    The pile driving activities are also not expected to have 
significant adverse effects on these affected marine mammals' habitats. 
The activities may cause some fish to leave the area of disturbance, 
thus temporarily impacting marine mammals' foraging opportunities in a 
limited portion of the foraging range; but, because of the short 
duration of the activities and the relatively small area of the habitat 
that may be affected (with no known particular importance to marine 
mammals), 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 specified activities will have only minor, short-term effects 
on individuals that will not have any bearing on those individuals' 
fitness. Thus the specified activities are not expected to impact rates 
of recruitment or survival and will therefore have a negligible impact 
on those species or stocks.
    In summary and as described above, the following factors primarily 
support our preliminary 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;
     The anticipated incidents of Level B harassment consist 
of, at worst, temporary modifications in behavior;
     The additional impact of PTS of a slight degree to few 
individual harbor seals at two locations in year 1 and one location in 
year 2 is not anticipated to increase individual impacts to a point 
where any population-level impacts might be expected;
     The absence of any significant habitat within the 
industrialized project areas, including known areas or features of 
special significance for foraging or reproduction; and
     The presumed efficacy of the proposed mitigation measures 
in reducing the effects of the specified activity to the level of least 
practicable adverse impact.
     Effects on species that serve as prey for marine mammals 
from the activities 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 from either project;
     The ensonifed areas from both projects are very small 
relative to the overall habitat ranges of all species and stocks, and 
will not cause more than minor impacts in any ESA-designated critical 
habitat, BIAs or any other areas of known biological importance.
    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 proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity, specific to each of the Year 1 
and Year 2 IHAs, will have a negligible impact on all affected marine 
mammal species or stocks.

Small Numbers

    As noted previously, only take of small numbers of marine mammals 
may be authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the 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 less 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.
    We propose to authorize incidental take of 14 marine mammal stocks 
each project year (table 11). The total amount of taking proposed for 
authorization is less than 1 percent for eight of these stocks in year 
1 and year 2, equal or less than 10 percent for an additional four 
stocks in year 1 and three stocks in year 2, and equal or less than 27 
percent for another stock in year 1 and three stocks in year 2, all of 
which we consider relatively small percentages and thus small numbers 
of marine mammals relative to the estimated overall population 
abundances for those stocks.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds, for each 
of the Year 1 and Year 2 IHAs, that small numbers of marine mammals 
would be taken relative to the population size of the affected species 
or stocks.

Unmitigable Adverse Impact Analysis and Determination

    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.

Endangered Species Act

    Section 7(a)(2) of the ESA of 1973 (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, in this case with the West Coast Regional Office.
    NMFS is proposing to authorize take of SRKW, as well as two DPSs of 
humpback whale (Central American/Southern Mexico--California--Oregon--
Washington and Mainland Mexico--California--Oregon--Washington), which 
are listed under the ESA.
    The NMFS Office of Protected Resources has requested initiation of 
section 7 consultation with the NMFS West Coast Region for the issuance 
of these IHAs. NMFS will conclude the ESA consultation prior to 
reaching a determination regarding the proposed issuance of the 
authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue two consecutive IHAs to the Navy for conducting the NAVFAC NW MPR 
Project in Puget Sound, Washington between July 2024 and July 2025, and 
July 2025 and July 2026, provided the previously mentioned mitigation,

[[Page 25608]]

monitoring, and reporting requirements are incorporated. Drafts of the 
proposed IHAs can be found at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    We request comment on our analyses, the proposed authorizations, 
and any other aspect of this notice of proposed IHAs for the proposed 
construction project. We also request comment on the potential renewal 
of these proposed IHAs as described in the paragraph below. Please 
include with your comments any supporting data or literature citations 
to help inform decisions on the request for each IHA or a subsequent 
renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time, one-year 
renewal IHA following notice to the public providing an additional 15 
days for public comments when (1) up to another year of identical or 
nearly identical activities as described in the Description of Proposed 
Activity section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activity section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed renewal IHA effective date (recognizing that the 
renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
    Upon review of the request for renewal, the status of the affected 
species or stocks, and any other pertinent information, NMFS determines 
that there are no more than minor changes in the activities, the 
mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: April 5, 2024.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2024-07676 Filed 4-10-24; 8:45 am]
BILLING CODE 3510-22-P