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Notice2025-10046

Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Alaska Department of Transportation and Public Facilities Prince William Sound Ferry Terminal Improvement Projects in Cordova, Chenega, and Tatitlek, Alaska

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Published

June 4, 2025

Issuing agencies

Commerce DepartmentNational Oceanic and Atmospheric Administration

Abstract

NMFS has received a request from the Alaska Department of Transportation and Public Facilities (ADOT&PF) for authorization to take marine mammals incidental to the Prince William Sound Ferry Terminal Improvement Projects (PWS Projects) in Cordova, Chenega, and Tatitlek, Alaska. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue three incidental harassment authorizations (IHAs) to incidentally take marine mammals during the specified activities associated with each of the three projects. NMFS is also requesting comments on possible one-time, 1-year renewals 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.

Full Text

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[Federal Register Volume 90, Number 106 (Wednesday, June 4, 2025)]
[Notices]
[Pages 23814-23848]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-10046]

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Vol. 90

Wednesday,

No. 106

June 4, 2025

Part III

Department of Commerce

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National Oceanic and Atmospheric Administration

Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to the Alaska Department of Transportation
and Public Facilities Prince William Sound Ferry Terminal Improvement
Projects in Cordova, Chenega, and Tatitlek, Alaska; Notice

Federal Register / Vol. 90 , No. 106 / Wednesday, June 4, 2025 /
Notices

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XE765]

Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Alaska Department of
Transportation and Public Facilities Prince William Sound Ferry
Terminal Improvement Projects in Cordova, Chenega, and Tatitlek, Alaska

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 renewals.

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SUMMARY: NMFS has received a request from the Alaska Department of
Transportation and Public Facilities (ADOT&PF) for authorization to
take marine mammals incidental to the Prince William Sound Ferry
Terminal Improvement Projects (PWS Projects) in Cordova, Chenega, and
Tatitlek, Alaska. Pursuant to the Marine Mammal Protection Act (MMPA),
NMFS is requesting comments on its proposal to issue three incidental
harassment authorizations (IHAs) to incidentally take marine mammals
during the specified activities associated with each of the three
projects. NMFS is also requesting comments on possible one-time, 1-year
renewals 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 July 7,
2025.

ADDRESSES: Comments should be addressed to Permits and Conservation
Division, Office of Protected Resources, National Marine Fisheries
Service and should be submitted via email to <a href="/cdn-cgi/l/email-protection#6c25383c420403180f040705022c02030d0d420b031a"><span class="__cf_email__" data-cfemail="d9908d89f7b1b6adbab1b2b0b799b7b6b8b8f7beb6af">[email&#160;protected]</span></a>.
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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. In
case of problems accessing these documents, please call the contact
listed below.
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 <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> 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: Cara Hotchkin, 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
``mitigation''); and requirements pertaining to the monitoring and
reporting of the takings. The definitions of all applicable MMPA
statutory terms used above are included in the relevant sections below
and can be found in section 3 of the MMPA (16 U.S.C. 1362) and NMFS
regulations at 50 CFR 216.103.

National Environmental Policy Act

To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an IHA)
with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for 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 IHA 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
IHA requests.

Summary of Request

On September 9, 2024, NMFS received a request from ADOT&PF for
three IHAs to take marine mammals incidental to pile driving
(installation and removal) associated with construction to improve
three existing ferry terminals in Cordova, Chenega, and Tatitlek,
Alaska. Following NMFS' review of the application, ADOT&PF submitted
revised versions of their request on December 23, 2024, February 18,
2025, and March 13, 2025. The application was deemed adequate and
complete on April 15, 2025. ADOT&PF's request is for take of 8 species
(13 stocks) of marine mammals by Level B harassment and, for a subset
of 5 of these species, Level A harassment. Neither ADOT&PF nor NMFS
expect serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

The ADOT&PF, in cooperation with the Maritime Administration and
the Prince William Sound Economic Development District, proposes to
improve and modify three existing ferry terminals and associated
structures at the Cordova Ferry Terminal (Cordova Project), the Chenega
Ferry Terminal (Chenega Project), and the Tatitlek Ferry Terminal
(Tatitlek Project) located in

[[Page 23815]]

the Prince William Sound (PWS), Alaska.
The Cordova Project would modify the existing stern- and side-berth
docking facilities in Cordova, Alaska. The Chenega Project would
construct a new side-loading ferry terminal and this includes an
approach causeway, vehicle transfer bridge support floats, and mooring
structures in Chenega Bay, Alaska. The Tatitlek Project would require
retrofitting the existing end-loading ferry terminal facility and
construction includes a vehicle transfer bridge, a bridge support float
(or bridge support) to replace the existing tidal ramp facility in
Tatitlek, Alaska.
The ferry terminals require the proposed modifications to
accommodate larger Alaska Marine Highway System (AMHS) Alaska Class
Ferry Vessels (ACFV) which would replace the existing smaller class
ferry vessels that would be phased out. Construction activities
included as part of the PWS Projects with the potential to result in
Level A and B harassment of marine mammals from underwater sound
production include vibratory and impact installation, vibratory
removal, and down-the-hole (DTH) installation (Chenega and Tatitlek
only) of steel pipe piles.

Dates and Duration

Each of the three separate IHAs would be effective for one year
from January 1, 2027 through December 31, 2027. ADOT&PF anticipates
that in-water construction for the Cordova Project would occur over 60
non-consecutive days within a 3-month construction window beginning in
the summer of 2027, with 20 days for pile removal, 12 days for the
installation of temporary piles, and 28 days for the installation of
permanent mooring dolphins. Construction for the Chenega Project is
anticipated to occur over 156 non-consecutive days within a 4-month
construction window beginning in the summer of 2027, with 20 days for
installation and removal of temporary piles and 136 days for the
installation of permanent piles and tension anchors. The Tatitlek
Project construction is anticipated to occur over a total of 76 non-
consecutive days within a 4-month construction window beginning in the
summer of 2027, with 4 days for pile removal, 14 days for temporary
pile installation and removal, and 58 days for permanent pile
installation. The ADOT&PF conservatively estimated pile installation
and removal rates at all three project sites to account for weather
conditions, construction and mechanical delays, protected species
shutdowns, and logistical constraints.

Specific Geographic Region

The Cordova, Chenega, and Tatitlek Project sites are located
throughout the PWS southeast of Anchorage, Alaska (figure 1). The
Cordova Project is located on the east side of PWS in Orca Inlet,
northwest of the Copper River Delta in Cordova, Alaska (figure 2). Orca
Inlet is approximately 28 kilometers (km) long, varies from 2.5 to 5 km
wide, and leads to the Strawberry Channel out to the Gulf of Alaska.
The southern and central areas of the inlet are filled with sediment,
making the area very shallow with exposed mudflats during low tides.
The bathymetry is predominantly mud and sand, with rocks closer to
shore. Depths are shallower toward the mouth of Orca Inlet, generally 4
meters (m) or less with few, discontinuous channels. Freshwater inputs
to Orca Inlet near the Cordova Project vicinity include multiple
anadromous streams: Fleming Creek, Ocean Dock Creek, Odiak Slough, and
Eccles Creek. Orca Inlet is generally characterized by semidiurnal
tides averaging 3.5 m that can exceed 6.5 m during the highest spring
tides (Adelfio 2016). The city of Cordova has elevated background in-
air and underwater acoustic conditions within proximity to the Cordova
Project site because of the industrial activities, commercial fishing,
and recreational boating.
The Chenega Project site is located between Crab Bay and Sawmill
Bay on the east side of Evans Island, in the southwest corner of PWS
(figure 3). Chenega is connected to the Gulf of Alaska through
Elrington Passage to the south. The bathymetry of Sawmill Bay is
variable depending on location and proximity to shore, islands, or
rocks; depths range from 20 to 60 m, and up to 155 m toward the mouth
of the bay. Freshwater input into Crab Bay includes an anadromous
stream, O'Brien Creek, and a couple of its unnamed tributaries. Sawmill
Bay is generally characterized by semidiurnal tides with a typical
tidal range of up to 5 m. Chenega has regular vessel activities
including commercial fishing and recreation boating as well as limited
industrial activities, all of which contribute to background in-air and
underwater noise within proximity to the project site.
The Tatitlek Project is located north of Port Fidalgo, at the
entrance to Boulder Bay and the Tatitlek Narrows on the east side of
PWS (figure 4). Tatitlek is a secluded area separated from the Pacific
Ocean by a series of islands. The bathymetry of the project area is
variable by location and depends on the proximity shore, islands or
rocks. Depths approach 140 m or more within Port Fidalgo, up to 37 m in
Boulder Bay, and as shallow as 3 m within the Tatitlek Narrows. The
main navigation channel for Valdez, Alaska is within 15 km of the
project site. Freshwater inputs to the Tatitlek Narrows and Boulder Bay
include multiple anadromous streams: Nunu Creek, Borodkin Creek,
Tedishoff Creek, Brown Creek, Boardwalk Creek, and Katelnikoff Creek
are nearest. The Tatitlek Narrows are generally characterized by
semidiurnal tides with mean tidal ranges of around 5 m. The navigation
channel has regular oil tanker, tug boat, commercial fishing, and
recreational boating traffic which contribute to background in-air and
underwater noise levels within proximity to the project site.
BILLING CODE 3510-22-C

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BILLING CODE 3510-22-P

Detailed Description of the Specified Activity

The overall Project's purpose is to ensure that the Cordova,
Chenega, and Tatitlek ferry terminals can accommodate the new ACFVs, as
existing vessels serving these ports will be retired and the ACFVs
cannot be accommodated without reconfiguring

[[Page 23820]]

existing facilities or installing a separate facility. This Project
would ensure that ferry service, including the delivery of critical
goods, supplies, and passenger transportation, is not lost to these
coastal Alaska communities.
Cordova Ferry Terminal--The current stern berth of the Cordova
Ferry Terminal has a shallow water approach that can cause landing
issues for larger ACFVs, as it was built for a vessel that is no longer
being operated by the AMHS. The proposed side berth modifications will
make landing more efficient and reliable for the larger and newer ACF
vessels that are now being used to service this community.
The Cordova Project will involve the removal of five floating
fender dolphins, a four-pile dolphin fixed fender dolphin, and a 2-pile
catwalk support structure. Pile removal will include six vertical steel
pipe piles (30-inch (76 cm) diameter), three vertical steel pipe piles
(18-inch (46 cm) diameter), and 15 battered steel pipe piles (18-inch
(46 cm) diameter). 23 vertical and 18 battered steel pipe piles (30-
inch (76 cm) diameter) will be installed to create five new 5-pile
floating fender dolphins, and two new 4-pile fixed fender dolphins. Up
to 36 temporary 24-inch (61 cm) steel pipe piles will be installed to
support pile installation and will be removed following completion of
construction.
The installation of the permanent mooring dolphins would include
the installation of 20 30-inch (76 cm) steel pipe (ten vertical and ten
battered) piles, which would initially be installed with a vibratory
hammer to the point of refusal and then driven approximately 3 m with
an impact hammer to ensure structural capacity and pile embedment. See
table 1 for anticipated production rates for all pile types and
installation or removal methods. The exact duration or staging of each
pile installation method used will depend on sediment depth and
conditions at each pile location. Pile installation and removal will
occur in waters approximately 2-10 meters in depth.
Dredging would also occur around the stern berth of the fender line
to -7.6 m. Dredging is not expected to cause take of marine mammals
because dredging activities would not last for sufficient duration to
present the reasonable potential for disruption of behavioral patterns,
do not produce sound levels with likely potential to result in marine
mammal harassment, or some combination of the above, and are thus not
addressed further.

Table 1--Summary of Piles To Be Installed and Removed as Part of the Cordova Project
----------------------------------------------------------------------------------------------------------------
Typical
Impact Vibratory Total production Estimated
strikes duration duration rate in days of
Pile diameter and type Number of piles per pile per pile of activity piles per installation
(duration (minutes) per pile day or removal
in minutes) (hours) (range) (range)
----------------------------------------------------------------------------------------------------------------
Installation
----------------------------------------------------------------------------------------------------------------
24-inch (64 cm) steel pipe 36............. N/A 30 0.5 3 (2-4) 12 (9-18)
piles (temporary).
30-inch (76 cm) steel pipe 23 (vertical), 600 (60) 60 2 1.5 (1-2) 28 (21-41)
piles (permanent mooring 18 (battered).
dolphins).
----------------------------------------------------------------------------------------------------------------
Removal
----------------------------------------------------------------------------------------------------------------
18-inch (46 cm) steel pipe 3 (vertical), N/A 60 1 3 (2-4) 6 (5-18)
piles. 15 (battered).
24-inch (61 cm) steel pipe 36............. N/A 30 0.5 3 (2-4) 12 (9-18)
piles (temporary).
30-inch (76 cm) steel pipe 6.............. N/A 60 1 3 (2-4) 2 (2-3)
piles.
----------------------------------------------------------------------------------
Totals................... 138............ N/A N/A N/A N/A 60 (46-98)
----------------------------------------------------------------------------------------------------------------
Note: N/A means not applicable.

Chenega Ferry Terminal--The purpose of the Chenega Project is to
construct a new side berth facility to accommodate the ACFVs. The
Chenega Project will involve the installation of piles to support an
approach trestle, bridge abutment, two lift towers, and three mooring
dolphins. The approach trestle will involve the installation of 30 24-
inch (61 cm) vertical steel pipe piles. The bridge abutment will
necessitate the installation of six 30-inch (76 cm) vertical steel pipe
piles. The lift towers will involve the installation of eight 36-inch
(91 cm) vertical steel pipe piles. Twelve 30-inch (76 cm) steel pipe
piles (six vertical, six battered) will be used to support the three
mooring dolphins. Rock sockets will be required on all vertical
permanent piles, and tension anchors on most vertical and battered
permanent piles. Up to 30 temporary 24-inch (61 cm) steel pipe piles
will be installed to support pile installation and will be removed
following completion of construction.
Tension anchors would be installed in 36 permanent piles (eight 36-
inch (91 cm), 18 30-inch (76 cm), and 10 24-inch (61 cm) piles).
Tension anchors are installed within piles that are drilled into the
bedrock below the elevation of the pile tip after the pile has been
driven through the sediment layer to refusal. A 6- or 8-inch (15 or 20
cm) diameter steel pipe casing would be inserted inside the larger
diameter production pile and may be seated with a small pneumatic
hammer. A rock drill would be inserted into the casing, and a 6- to 8-
inch (15 to 20 cm) diameter hole would be drilled into bedrock with
rotary and percussion drilling methods. The drilling work is contained
within the steel pile casing and the steel pipe pile. The typical depth
of the drilled tension anchor hole varies, but 20-30 feet (ft; 6.1-9.1
meters (m)) is common. Rock fragments would be removed through the top
of the casing with compressed air. A steel rod would then be grouted
into the drilled hole and affixed to the top of the pile. The purpose
of a tension anchor is to secure the pile to the bedrock to withstand
uplift forces. It is estimated that tension anchor installation would
take between 1-4 hours per pile.
Pile removal would be conducted using a vibratory hammer. Pile
installation would be conducted using both a vibratory and an impact
hammer and DTH pile installation methods.

[[Page 23821]]

Piles would be advanced to refusal using a vibratory hammer. After DTH
pile installation, the final approximately 10 ft (3.0 m) of driving
would be conducted using an impact hammer so that the structural
capacity of the pile embedment can be verified. The exact duration or
staging of each pile installation method would depend on sediment depth
and conditions at each pile location. Pile installation and removal
would occur in waters approximately 6-7 m (20-23 ft) in depth. See
table 2 for anticipated production rates for all pile types and
installation or removal methods. Above-water construction activities or
fill placement to support the new approach causeway would also occur,
but would not last for sufficient duration to present the reasonable
potential for disruption of behavioral patterns, would not produce
sound levels with likely potential to result in marine mammal
harassment, or some combination of these, and are thus not addressed
further.

Table 2--Summary of Piles To Be Installed and Removed as Part of the Chenega Project
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Tension
Impact Rock socket anchor DTH
Number Number strikes Vibratory DTH pile pile Typical Estimated
of rock of per pile duration installation installation Total duration of production days of
Pile diameter and type Number of piles sockets tension (duration per pile duration duration activity per pile rate in installation
\1\ anchors in (minutes) (range) per (range) per (hours) piles per or removal
\2\ minutes) pile pile day (range) (range)
(minutes) (minutes)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Installation
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm) steel pipe piles 30..................... N/A N/A N/A 15 N/A N/A 0.25................... 3 (2-4) 10 (7.5-15)
(temporary).
24-inch (61 cm) steel pipe piles 30 (vertical).......... 30 10 50 (30) 15 240 (60-480) 120 (60-240) 6.75 (vertical)........ 0.33 (0-1) 70 (30-100)
(permanent; Approach Trestle).
30-inch (76 cm) steel pipe piles 6 (vertical)........... 6 12 50 (30) 15 240 (60-480) 120 (60-240) 6.75 (vertical)........ 0.33 (0-1) 36 (12-36)
(permanent; mooring dolphins). 6 (battered)........... 2.75 (battered)........
30-inch steel (76 cm) piles 6 (vertical)........... 6 6 50 (30) 15 240 (60-480) 120 (60-240) 6.75 (vert)............ 0.33 (0-1) 18 (6-24)
(Permanent; Bridge Abutment).
36-inch (91 cm) steel piles 8 (vertical)........... 8 8 50 (30) 15 240 (60-480) 120 (60-240) 6.75................... 0.33 (0-1) 24 (8-32)
(permanent; lift towers).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm) steel pipe piles 30..................... N/A N/A N/A 30 N/A N/A 0.5.................... 3 (2-4) 10 (7.5-15)
(temporary).
----------------------------------------------------------------------------------------------------------------------------------------------------------
Totals........................... 116.................... 50 36 N/A N/A N/A N/A N/A.................... N/A 156 (72-222)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Battered piles would not require rock sockets.
\2\ Maximum rock socket and tension anchor production rates assumes two days of drilling per socket, one day of drilling for tension anchors, and one day for impact/vibratory seating.
Note: N/A means not applicable.

Tatitlek Ferry Terminal--The Tatitlek Ferry Terminal is a
multipurpose dock structure that only supports stern berthing from the
Aurora Class vessels. Improvements to the dock are required to allow
the larger ACFVs to access Tatitlek and provide critical transportation
needs into the future. The Tatitlek Project ferry terminal
modifications would include a retrofit to the existing end-loading
ferry terminal facility to replace the existing tidal ramp facility,
including a new vehicle transfer bridge, mechanical support system for
the seaward end of the bridge, and two dolphins. These modifications
would require the removal of 11 existing steel pipe piles (20- and 30-
inch (51 and 76 cm) diameter) that support the existing dolphin and
ramp structures. To install the new access gangway, six 30-inch (76 cm)
steel piles would be installed for the bridge abutment, eight 36-inch
(91 cm) steel piles would be installed to support the lift towers, and
four vertical and four battered 30-inch (76 cm) piles would be
installed as mooring dolphins. Up to 20 temporary 24-inch (61 cm) steel
pipe piles would be installed to support pile installation and would be
removed following completion of construction. Tension anchors would be
required on all permanent piles, and rock sockets would be required on
all vertical permanent piles.
Piles would be installed via vibratory, impact, and DTH methods as
described for the Chenega Project. All permanent piles (vertical and
battered) would require tension anchors and all vertical permanent
piles would require rock sockets. Piles would be advanced to refusal
using a vibratory hammer. After DTH pile installation, the final
seating of the pile will be conducted using an impact hammer so that
the structural capacity of the pile embedment could be verified (i.e.,
proofing). Pile removal would be conducted using a vibratory hammer.
The exact duration or staging of each pile installation method would
depend on sediment depth and conditions at each pile location. Pile
installation and removal would occur in waters approximately 6-9 m in
depth. See table 3 for anticipated production rates for all pile types
and installation or removal methods.
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting).

[[Page 23822]]

Table 3--Summary of Piles To Be Installed and Removed as Part of the Tatitlek Project
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Tension
Impact Rock socket anchor DTH
Number Number strikes Vibratory DTH pile pile Typical Estimated
of rock of per pile duration installation installation Total duration of production days of
Pile diameter and type Number of piles sockets tension (duration per pile duration duration activity per pile rate in installation
\1\ anchors in (minutes) (range) per (range) per (hours) piles per or removal
\2\ minutes) pile pile day (range) (range)
(minutes) (minutes)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Installation
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm) steel pipe piles 20..................... N/A N/A N/A 15 N/A N/A 0.25................... 3 (2-4) 7 (5-10)
(temporary).
30-inch (76 cm) steel pipe piles 6...................... 6 6 50 (30) 15 240 (60-480) 120 (60-240) 6.75................... 0.33 (0-1) 18 (6-24)
(permanent; bridge abutment).
30-inch (76 cm) steel pipe piles 4 (vertical)........... 4 8 50 (30) 15 240 (60-480) 120 (60-240) 6.75 (vertical)........ 0.5 (0-1) 16 (8-24)
(permanent; mooring dolphins). 4 (battered)........... 2.75 (battered)........
36-inch (76 cm) steel pipe piles 8...................... 8 8 50 (30) 15 240 (60-480) 120 (60-240) 6.75................... 0.33 (0-1) 24 (8-32)
(permanent; lift towers).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
20-inch (51 cm) steel pipe piles 3...................... N/A N/A N/A 60 N/A N/A 1.0.................... 3 (2-3) 1 (1-2)
(dolphin).
24-inch (61 cm) steel pipe piles 20..................... N/A N/A N/A 30 N/A N/A 0.5.................... 3 (2-4) 7 (5-10)
(temporary).
30-inch (76 cm) steel pipe piles 8...................... N/A N/A N/A 60 N/A N/A 1.0.................... 3 (2-4) 3 (2-4)
(ramp).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Totals........................... 73..................... 18 22 N/A N/A N/A N/A N/A.................... N/A 76 (35-
105.5)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Battered piles would not require rock sockets.
\2\ Maximum rock socket and tension anchor production rates assumes two days of drilling per socket, one day of drilling for tension anchors, and one day for impact/vibratory seating.
Note: N/A means not applicable.

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; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 4 lists all species or stocks for which take is expected and
proposed to be authorized for each project activity and summarizes
information related to the population or stock, including regulatory
status under the MMPA and Endangered Species Act 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 (M/SI) from anthropogenic sources are included here as gross
indicators of the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprise 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. 2023 SARs. All values presented in table 4 are the most
recent available at the time of publication (including from the draft
2024 SARs) and are available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.

Table 4--Species With Estimated Take From the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stock abundance (CV,
Common name Scientific name Stock ESA/MMPA status; Nmin, most recent PBR Annual M/
strategic (Y/N) \1\ abundance survey) \2\ SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
Humpback Whale................. Megaptera novaeangliae Mexico-North Pacific.. T, D, Y N/A (N/A, N/A, 2006). UND4 0.57
Hawai[revaps]i........ -, -, N 11,278 (0.56, 7,265, 127 27.09
2020).
Minke Whale \4\................ Balaenoptera AK.................... -, -, N N/A (N/A, N/A, N/A).. UND 0
acutorostrata.
Family Delphinidae:

[[Page 23823]]

Killer Whale................... Orcinus orca.......... Eastern North Pacific -, -, N 1,920 (N/A, 1,920, 19 1.3
Alaska Resident. 2019).
AT1 (Chugach) -, D, Y 7 (N/A, 7, 2019)..... 0.1 0
Transient \5\.
Eastern Northern -, -, N 302 (N/A, 302, 2018). 2.2 0.2
Pacific Northern
Resident.
West Coast Transient.. -, -, N 349 (N/A, 349, 2018). 3.5 0.4
Pacific White-Sided Dolphin.... Lagenorhynchus N Pacific............. -, -, N 26,880 (N/A, N/A, UND 0
obliquidens. 1990).
Family Phocoenidae (porpoises):
Dall's Porpoise \6\............ Phocoenoides dalli.... AK.................... -, -, N UND (UND, UND, 2015). UND 37
Harbor Porpoise................ Phocoena phocoena..... Gulf of Alaska........ -, -, Y 31,046 (0.21, N/A, UND 72
1998).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Steller Sea Lion \7\........... Eumetopias jubatus.... Western............... E, D, Y 49,837 (N/A, 49,837, 299 267
2022).
Eastern............... -, -, N 36,308 (N/A, 36,308, 2,178 93.2
2022).
Family Phocidae (earless seals):
Harbor Seal.................... Phoca vitulina........ Prince William Sound.. -, -, N 44,756 (N/A, 41,776, 1,253 413
2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region</a>. CV is the coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ Reliable population estimates are not available for this stock. Please see Friday et al. (2013) and Zerbini et al. (2006) for additional information
on numbers of minke whales in Alaska.
\5\ Nest is based upon counts of individuals identified from photo-ID catalogs. PBR has been calculated, however, a reliable estimate of the maximum net
productivity rate is not available for this stock, and the default cetacean maximum theoretical net productivity rate was used for the PBR
calculation.
\6\ The best available abundance estimate is likely an underestimate for the entire stock because it is based upon a survey that covered only a small
portion of the stock's range.
\7\ 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 8 species (with 13 managed stocks) in table
4 temporally and spatially co-occur with the activity to the degree
that take is reasonably likely to occur. While gray whales
(Eschrichtius robustus), sperm whales (Physeter microcephalus),
northern elephant seals (Mirounga angustirostris), and northern fur
seals (Callorhinus ursinus) have been documented in PWS, 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. These species are all considered rare (no
sightings in recent years), very rare (no local knowledge of sightings
within the project vicinity), or are generally restricted to offshore
waters in deep water, thus take is not expected to occur, and it is not
discussed further in this notice.
Sea otters may be found in PWS, however, sea otters are managed by
the U.S. Fish and Wildlife Service and are not considered further in
this document.

Humpback Whale

Humpback whales are the most commonly observed baleen whale in
Alaska and have been observed in Southeast Alaska in all months of the
year (Baker et al., 1986). They undergo seasonal migrations in Alaska
from spring until fall with other whale species present.
Three stocks may occur in the project areas: the Western North
Pacific stock, the Mexico-North Pacific stock, and the Hawaii Stock. In
the project areas, Hawaii stock is the most predominant and make up
approximately 89 percent of humpbacks occurring in the Gulf of Alaska.
The Mexico-North Pacific stock is expected to represent approximately
11 percent, while the Western North Pacific stock represents less than
1 percent of humpbacks observed within the project areas (Wade, 2021).
Critical habitat for humpback whales in Alaska was updated in 2021
(86 FR 21082). This designated critical habitat overlaps with all three
of the proposed PWS Project sites. All three PWS Project sites would
also occur within (Chenega, Tatitlek) or in close proximity to
(Cordova) a seasonal humpback whale feeding Biologically Important Area
(BIA) for the months of September through December, and March through
May (Wild et al. 2023).

Minke Whale

Minke whales are found throughout the northern hemisphere in polar,
temperate, and tropical waters. The International Whaling Commission
has identified three minke whale stocks in the North Pacific: one near
the Sea of Japan, a second in the rest of the western Pacific (west of
180[deg] W), and a third, less concentrated stock throughout the
eastern Pacific. NMFS further splits this third stock between Alaska
whales and resident whales of California, Oregon, and Washington (Muto
et al., 2018). Minke whales are found in all Alaska waters, however no
population estimates are currently available for the Alaska stock.
Minke whales are generally found in shallow, coastal waters within
200 m (656 ft) of shore (Zerbini et al., 2006). Dedicated surveys for
cetaceans in southeast Alaska found that minke whales were scattered
throughout inland waters from Glacier Bay and Icy Strait to Clarence
Strait, with small concentrations near the entrance of Glacier Bay.
Surveys took place in spring, summer, and fall, and minke whales were
present in low numbers in all seasons and years (Dahlheim et al.,
2009). Additionally, minke whales were

[[Page 23824]]

observed during the Biorka Island Dock Replacement Project at the mouth
of Sitka Sound (Turnagain Marine Construction, 2018).

Killer Whale

Killer whales have been observed in all oceans, but the highest
densities occur in colder and more productive waters found at high
latitudes. Killer whales occur along the entire coast of Alaska (Braham
and Dahlheim, 1982), inland waterways of British Columbia and
Washington (Bigg et al., 1990), and along the outer coasts of
Washington, Oregon, and California (Green et al., 1992; Barlow, 1995,
1997; Forney et al., 1995). Resident killer whales in the eastern North
Pacific primarily feed on salmonids, and show distinct preference for
Chinook salmon, whereas transient killer whales primarily hunt and feed
on marine mammals, including harbor seals, Dall's porpoise, harbor
porpoises, and sea lions (Muto et. al., 2020). Eight stocks of killer
whales are recognized within the Pacific U.S. Exclusive Economic Zone
(Muto et al., 2020). Of those, four stocks are that are most likely to
occur in the PWS at all three project sites and include: (1) Eastern
North Pacific Alaska Resident stock, (2) AT1 (Chugach) Transient stock,
(3) Eastern North Pacific Northern Resident stock, and (4) West Coast
Transient stock. For the PWS Projects at Cordova, Chenega, and
Tatitlek, all stocks are expected to occur in the proposed project
areas during the proposed in-water work.

Pacific White-Sided Dolphins

The Pacific white-sided dolphin is found in temperate waters of the
North Pacific from the southern Gulf of California to Alaska. Across
the North Pacific, it appears to occur between 33[deg] N and 47 [deg] N
(Young et al., 2023; Waite and Shelden, 2018). In the eastern North
Pacific Ocean, the Pacific white-sided dolphin is one of the most
common cetacean species, occurring primarily in shelf and slope waters
(Green et al., 1993; Barlow 2003, 2010). During winter, this species is
most abundant in California slope and offshore areas; as northern
waters begin to warm in the spring, it appears to move north to slope
and offshore waters off Oregon/Washington (Green et al., 1992, 1993;
Forney et al., 1995; Buchanan et al., 2001; Barlow, 2003). Pacific
White-sided are highly gregarious and typically observed in groups from
10 to 100 individuals but groups can range into the thousands.

Dall's Porpoise

Dall's porpoise is found in temperate to subarctic waters of the
North Pacific and adjacent seas (Jefferson et al., 2015). It is widely
distributed across the North Pacific over the continental shelf and
slope waters, and over deep (greater than 2,500 m) oceanic waters
(Friday et al., 2012; Friday et al., 2013). It is probably the most
abundant small cetacean in the North Pacific Ocean, and its abundance
changes seasonally, likely in relation to water temperature (Becker,
2007).
Dall's porpoises are common in the PWS and have been documented in
a wide range of habitats, such as bays, shallow water, and nearshore
waters. Observations of groups in the Prince William Sound Range
between 1 to 18 animals per group (Moran et. al., 2018).

Harbor Porpoise

There are six harbor porpoise stocks in Alaska: the Bering Sea
stock occurs throughout the Aleutian Islands and all waters north of
Unimak Pass; the Gulf of Alaska stock occurs from Cape Suckling to
Unimak Pass; the Northern Southeast Alaska Inland Waters stock includes
Cross Sound, Glacier Bay, Icy Strait, Chatham Strait, Frederick Sound,
Stephens Passage, Lynn Canal, and adjacent inlets; the Southern
Southeast Alaska Inland Waters stock encompasses Sumner Strait,
including areas around Wrangell and Zarembo Islands, Clarence Strait,
and adjacent inlets and channels within the inland waters of Southeast
Alaska north-northeast of Dixon Entrance; and the Yakutat/Southeast
Alaska Offshore Waters stock includes offshore habitats in the Gulf of
Alaska west of the Southeast Alaska inland waters and the areas around
Yakutat Bay (Young et al., 2023). Only the Gulf of Alaska stocks are
expected to be encountered throughout all three PWS Project sites.

Steller Sea Lion

The Steller sea lion's range extends across the North Pacific Rim
from northern Japan to California with areas of abundance in the Gulf
of Alaska and Aleutian Islands (Muto et al., 2020). In 1997, based on
demographic and genetic dissimilarities, NMFS identified two DPSs of
Steller sea lions under the ESA: a western DPS (western stock) and an
eastern DPS (eastern stock). The western DPS breeds on rookeries
located west of 144[deg] W in Alaska and Russia, whereas the eastern
DPS breeds on rookeries in southeast Alaska through California.
Movement occurs between the western and eastern DPSs of Steller sea
lions, and increasing numbers of individuals from the western DPS have
been seen in southeast Alaska in recent years (Muto et al., 2020; Fritz
et al., 2016). This DPS-exchange is especially evident in the outer
southeast coast of Alaska, including Sitka Sound. Hastings et al.
(2020) indicates that the Eastern stock is increasing while the Western
stock is decreasing, influencing mixing of both populations at new
rookeries in northern southeast Alaska. Steller Sea Lion critical
habitat has been defined in Alaska within 20 nautical miles (nmi; 37
km) of major haulouts and major rookeries (50 CFR 226.202). All three
project sites have identified haulouts within this radius; the nearest
haulouts are 35.7 km from Cordova, 14 km from Chenega, and 25.9 km from
Tatitlek.

Harbor Seal

Harbor seals are common in the coastal and inside waters of the
project areas. Harbor seals in Alaska are typically non-migratory with
local movements attributed to factors such as prey availability,
weather, and reproduction (Scheffer and Slipp, 1944; Fisher, 1952; Bigg
1969, 1981; Hastings et al., 2004). Harbor seals haul out of the water
periodically to rest, give birth, and nurse their pups. There are 12
stocks of harbor seals in Alaska but only the Prince William Stock is
expected to occur at all three PWS Project action areas.

Marine Mammal Hearing

Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al.
(2007, 2019) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges (behavioral response
data, anatomical modeling, etc.). Subsequently, NMFS (2018, 2024)
described generalized hearing ranges for these marine mammal hearing
groups. Generalized hearing ranges were chosen based on the
approximately 65-decibel (dB) threshold from the normalized composite
audiograms, with the exception for lower limits for low-frequency
cetaceans where the lower bound was deemed to be biologically
implausible and the lower bound from Southall et al. (2007)

[[Page 23825]]

retained. We note that the names of two hearing groups and the
generalized hearing ranges of all marine mammal hearing groups have
been recently updated (NMFS 2024) as reflected below in table 5.

Table 5--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
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).
Hz = hertz; kHz = kilohertz.

For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.

Potential 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.

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 10-20 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 activities 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 proposed
project would include impact pile driving, vibratory pile driving and
removal, and DTH. 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 for Occupational Safety and
Health (NIOSH), 1998; ANSI, 2005; 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 pile hammers would be used on PWS Projects: impact,
vibratory, and DTH. Impact hammers operate by repeatedly dropping 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).
Rock socket or tension anchoring would be conducted using a DTH
hammer. 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 the DTH hammer to increase speed of progress
through the substrate (i.e., it is similar to a ``hammer drill'' hand
tool). Rock anchoring or socketing involves using DTH

[[Page 23826]]

equipment to create a hole in the bedrock inside which the pile is
placed to give it lateral and longitudinal strength. Tension anchoring
involves creating a smaller hole below the bottom of a pile. A length
of rebar is typically inserted in the small hole and is long enough to
run up through the middle of a hollow pile to reach the surface where
it is connected to the pile to provide additional mechanical support
and stability to the pile. The sounds produced by DTH systems contain
both a continuous, non-impulsive component from the drilling action and
an impulsive component from the hammering effect. Therefore, NMFS
treats DTH systems as both impulsive (for estimating Level A harassment
zones) and non-impulsive (for estimating Level B harassment zones)
sound source types simultaneously.
The likely or possible impacts of the ADOT&PF's proposed activity
on marine mammals could involve both non-acoustic and acoustic
stressors. Potential non-acoustic stressors could result from the
physical presence of the equipment and personnel; however, any impacts
to marine mammals are expected to primarily be acoustic in nature.

Potential Effects of Underwater Sound on Marine Mammals

The introduction of anthropogenic noise into the aquatic
environment from DTH and pile driving and removal is the means by which
marine mammals may be harassed from the ADOT&PF's specified activity.
Anthropogenic sounds cover a broad range of frequencies and sound
levels and can have a range of highly variable impacts on marine life
from none or minor to potentially severe responses depending on
received levels, duration of exposure, behavioral context, and various
other factors. Broadly, underwater sound from active acoustic sources,
such as those in the Project, can potentially result in one or more of
the following: temporary or permanent hearing impairment, non-auditory
physical or physiological effects, behavioral disturbance, stress, and
masking (Richardson et al., 1995; Gordon et al., 2003; Nowacek et al.,
2007; Southall et al., 2007; G[ouml]tz et al., 2009).
We describe the more severe effects of certain non-auditory
physical or physiological effects only briefly as we do not expect that
use of pile driving hammers (impact, vibratory, and DTH) are reasonably
likely to result in such effects (see below for further discussion).
Potential effects from impulsive sound sources can range in severity
from effects such as behavioral disturbance or tactile perception to
physical discomfort, slight injury of the internal organs and the
auditory system, or mortality (Yelverton et al., 1973). Non-auditory
physiological effects or injuries that theoretically might occur in
marine mammals exposed to high level underwater sound or as a secondary
effect of extreme behavioral reactions (e.g., change in dive profile as
a result of an avoidance reaction) caused by exposure to sound include
neurological effects, bubble formation, resonance effects, and other
types of organ or tissue damage (Cox et al., 2006; Southall et al.,
2007; Zimmer and Tyack, 2007; Tal et al., 2015). The Project activities
considered here do not involve the use of devices such as explosives or
mid-frequency tactical sonar that are associated with these types of
effects.
In general, animals exposed to natural or anthropogenic sound may
experience physical and psychological effects, ranging in magnitude
from none to severe (Southall et al., 2007, 2019). Exposure to
anthropogenic noise has the potential to result in auditory threshold
shifts and behavioral reactions (e.g., avoidance, temporary cessation
of foraging and vocalizing, changes in dive behavior). It can also lead
to non-observable physiological responses, such 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 degree of effect of an acoustic exposure on marine mammals is
dependent on several factors, including, but not limited to, sound type
(e.g., impulsive vs. non-impulsive), signal characteristics, the
species, age and sex class (e.g., adult male vs. mom with calf),
duration of exposure, the distance between the noise source and the
animal, received levels, behavioral state at time of exposure, and
previous history with exposure (Wartzok et al., 2004; Southall et al.,
2007). In general, sudden, high-intensity sounds can cause hearing loss
as can longer exposures to lower-intensity sounds. Moreover, any
temporary or permanent loss of hearing, if it occurs at all, will occur
almost exclusively for noise within an animal's hearing range. We
describe below the specific manifestations of acoustic effects that may
occur based on the activities proposed by ADOT&PF.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First (at the greatest distance) is the area within which the
acoustic signal would be audible (potentially perceived) to the animal
but not strong enough to elicit any overt behavioral or physiological
response. The next zone (closer to the receiving animal) corresponds
with the area where the signal is audible to the animal and of
sufficient intensity to elicit behavioral or physiological
responsiveness. The third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory or other systems. Overlaying
these zones to a certain extent is the area within which masking (i.e.,
when a sound interferes with or masks the ability of an animal to
detect a signal of interest that is above the absolute hearing
threshold) may occur; the masking zone may be highly variable in size.
Below, we provide additional detail regarding potential impacts on
marine mammals and their habitat from noise in general, starting with
hearing impairment, as well as from the specific activities ADOT&PF
plans to conduct, to the degree it is available.
Auditory Injury (AUD INJ) and Permanent Threshold Shift (PTS)--NMFS
defines auditory injury as ``damage to the inner ear that can result in
destruction of tissue . . . which may or may not result in PTS'' (NMFS,
2024). NMFS defines PTS as a permanent, irreversible increase in the
threshold of audibility at a specified frequency or portion of an
individual's hearing range above a previously established reference
level (NMFS, 2024). PTS does not generally affect more than a limited
frequency range, and an animal that has incurred PTS has incurred some
level of hearing loss at the relevant frequencies; typically, animals
with PTS are not functionally deaf (Au and Hastings, 2008; Finneran,
2016). Available data from humans and other terrestrial mammals
indicate that a 40-dB threshold shift approximates PTS onset (see Ward
et al., 1958, 1959, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et
al., 1996; Henderson et al., 2008). PTS levels for marine mammals are
estimates, as with the exception of a single study unintentionally
inducing PTS in a harbor seal (Kastak et al., 2008), there are no
empirical data measuring PTS in marine mammals largely due to the fact
that, for various ethical reasons, experiments involving anthropogenic
noise exposure at levels inducing PTS are not typically pursued or
authorized (NMFS, 2018).
Temporary Threshold Shift (TTS)--TTS is a temporary, reversible
increase in the threshold of audibility at a specified frequency or
portion of an

[[Page 23827]]

individual's hearing range above a previously established reference
level (NMFS, 2018). Based on data from cetacean TTS measurements
(Southall et al., 2007, 2019), 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, 2002). As described in Finneran (2015), 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 auditory
masking, below). For example, a marine mammal may be able to readily
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during 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 a time when
communication is critical for successful mother/calf interactions could
have more serious impacts. We note that reduced hearing sensitivity as
a simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al., 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without cost.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. For
pinnipeds in water, measurements of TTS are limited to harbor seals,
elephant seals (Mirounga angustirostris), bearded seals (Erignathus
barbatus) and California sea lions (Zalophus californianus) (Kastak et
al., 1999, 2007; Kastelein et al., 2019b, 2019c, 2021, 2022a, 2022b;
Reichmuth et al., 2019; Sills et al., 2020). These studies examined
hearing thresholds measured in marine mammals before and after exposure
to intense or long-duration sound exposures. The difference between the
pre-exposure and post-exposure thresholds can be used to determine the
amount of TS at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity
for a species or hearing group, are less hazardous than those at higher
frequencies, near the region of best sensitivity (Finneran and
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are
higher compared to those in the region of best sensitivity (i.e., a low
frequency noise would need to be louder to cause TTS onset when TTS
exposure level is higher), as shown for harbor porpoises and harbor
seals (Kastelein et al., 2019a, 2019c). Note that in general, harbor
seals have a lower TTS onset than other measured pinniped species
(Finneran, 2015). In addition, TTS can accumulate across multiple
exposures, but the resulting TTS will be less than the TTS from a
single, continuous exposure with the same SEL (Mooney et al., 2009;
Finneran et al., 2010; Kastelein et al., 2014, 2015). This means that
TTS predictions based on the total, SELcum will overestimate the amount
of TTS from intermittent exposures, such as sonars and impulsive
sources. Nachtigall et al. (2018) describes measurements of hearing
sensitivity of multiple odontocete species (i.e., bottlenose dolphin,
harbor porpoise, beluga, and false killer whale (Pseudorca crassidens))
when a relatively loud sound was preceded by a warning sound. These
captive animals were shown to reduce hearing sensitivity when warned of
an impending intense sound. Based on these experimental observations of
captive animals, the authors suggest that wild animals may dampen their
hearing during prolonged exposures or if conditioned to anticipate
intense sounds. Another study showed that echolocating animals
(including odontocetes) might have anatomical specializations that
might allow for conditioned hearing reduction and filtering of low-
frequency ambient noise, including increased stiffness and control of
middle ear structures and placement of inner ear structures (Ketten et
al., 2021). Additionally, the existing marine mammal TTS data come from
a limited number of individuals within these species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, but such relationships are assumed to be similar to
those in humans and other terrestrial mammals. PTS typically occurs at
exposure levels at least several dBs above that inducing mild TTS
(e.g., a 40-dB TS approximates PTS onset (Kryter et al., 1966; Miller,
1974), while a 6-dB TS approximates TTS onset (Southall et al., 2007,
2019). Based on data from terrestrial mammals, a precautionary
assumption is that the PTS thresholds for impulsive sounds (such as
impact pile driving pulses as received close to the source) are at
least 6 dB higher than the TTS threshold on a peak-pressure basis and
PTS SELcum thresholds are 15 to 20 dB higher than TTS SELcum thresholds
(Southall et al., 2007, 2019). Given the higher level of sound or
longer exposure duration necessary to cause PTS as compared with TTS,
it is considerably less likely that PTS could occur.
Pile installation at PWS Project Sites would require a combination
DTH, impact, and vibratory pile driving and removal. Construction at
each of PWS Project sites would occur independently and only one method
of pile installation or removal would occur at each site at a time.
Proposed construction activities at each project site are not expected
to be constant and pauses in the activities producing sound are likely
to occur each day. Given these pauses and 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 Harassment--Exposure to noise from pile driving and
removal also have the potential to behaviorally disturb marine mammals.
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

[[Page 23828]]

Bejder, 2007; Weilgart, 2007; NRC, 2005).
Disturbance may result in changing durations of surfacing and
dives, number of blows per surfacing, or moving direction and/or speed;
reduced/increased vocal activities; changing/cessation of certain
behavioral activities (such as socializing or feeding); visible startle
response or aggressive behavior (such as tail/fluke slapping or jaw
clapping); avoidance of areas where sound sources are located.
Pinnipeds may increase their haul out time, possibly to avoid in-water
disturbance (Thorson and Reyff, 2006). Behavioral responses to sound
are highly variable and context-specific and any reactions depend on
numerous intrinsic and extrinsic factors (e.g., species, state of
maturity, experience, current activity, reproductive state, auditory
sensitivity, time of day), as well as the interplay between factors
(e.g., Richardson et al., 1995; Wartzok et al., 2004; Southall et al.,
2007, 2021; Weilgart, 2007; Archer et al., 2010). Behavioral reactions
can vary not only among individuals but also within exposures of an
individual, depending on previous experience with a sound source,
context, and numerous other factors (Ellison et al., 2012, Southall et
al., 2021), 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). In general, pinnipeds seem more
tolerant of, or at least habituate more quickly to, potentially
disturbing underwater sound than do cetaceans, and generally seem to be
less responsive to exposure to industrial sound than most cetaceans.
For a review of the studies involving marine mammal behavioral
responses to sound, see Southall et al., 2007; Gomez et al., 2016; and
Southall et al., 2021 reviews.
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). A determination of whether foraging disruptions incur fitness
consequences would require information on 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.
Airborne Acoustic Effects--Pinnipeds that occur near the project
sites could be exposed to airborne sounds associated with pile driving
or DTH that have the potential to cause behavioral harassment,
depending on their distance from the 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 sites within the range of noise
levels elevated above the airborne acoustic harassment criteria. We
recognize that pinnipeds in the water could be exposed to airborne
sound that may result in behavioral harassment when swimming with their
heads above water. Most likely, airborne sound would cause behavioral
responses similar to those discussed above in relation to underwater
sound. For instance, anthropogenic sound could cause hauled-out
pinnipeds to exhibit changes in their normal behavior, such as
reduction in vocalizations, or cause them to temporarily abandon the
area and move further from the source. However, these animals would
previously have been `taken' because of exposure to underwater sound
above the behavioral harassment thresholds, which are in all cases
larger than those associated with airborne sound. Thus, the behavioral
harassment of these animals is already accounted for in these estimates
of potential take. Therefore, we do not believe that authorization of
incidental take resulting from airborne sound for pinnipeds is
warranted, and airborne sound is not discussed further here.
Stress Response--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 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, 2005), however
distress is an unlikely result of this project based on observations of
marine mammals during previous, similar construction projects around
PWS.
Auditory Masking--Sound can disrupt behavior through masking, or

[[Page 23829]]

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; Erbe et al.,
2016). 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.,
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.
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is man-made, it may be considered harassment
when disrupting or altering critical behaviors. It is important to
distinguish TTS and PTS, which persist after the sound exposure, from
masking, which occurs during the sound exposure. Because masking
(without resulting in TS) is not associated with abnormal physiological
function, it is not considered a physiological effect, but rather a
potential behavioral effect.
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Houser and Moore, 2014). Masking can be tested
directly in captive species (e.g., Erbe, 2008), but in wild populations
it must be either modeled or inferred from evidence of masking
compensation. There are few studies addressing real-world masking
sounds likely to be experienced by marine mammals in the wild (e.g.,
Branstetter et al., 2013).
Masking affects both senders and receivers of acoustic signals and
can potentially have long-term chronic effects on marine mammals at the
population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than
three times in terms of SPL) in the world's ocean from pre-industrial
periods, with most of the increase from distant commercial shipping
(Hildebrand, 2009). All anthropogenic sound sources, but especially
chronic and lower-frequency signals (e.g., from vessel traffic),
contribute to elevated ambient sound levels, thus intensifying masking.
Project sites at Cordova, Chenega, and Tatitlek are in areas with
commercial and recreational fishing, recreational boating, ferry
operations, vessel traffic associated with crude oil transport from
Valdez, Alaska, and local industrial activities; therefore, background
sound levels are generally already elevated.

Marine Mammal Habitat Effects

The ADOT&PF's proposed construction activities could have
localized, temporary impacts on marine mammal habitat, including prey,
by increasing in-water SPLs and slightly decreasing water quality.
Increased noise levels may affect acoustic habitat (see Auditory
Masking) and adversely affect marine mammal prey in the vicinity of the
project area (see discussion below). During DTH, impact, and vibratory
pile driving, elevated levels of underwater noise would ensonify
project areas where both fish 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.
Water Quality--In-water pile driving activities would also cause
short-term effects on water quality due to increased turbidity.
Temporary and localized increase in turbidity near the seafloor would
occur in the immediate area surrounding where piles are installed or
removed and where dredging and fill placement occurs due benthic
sediment disturbance. In general, turbidity associated with pile
installation is localized to about a 25 ft (7.6 m) radius around the
pile (Everitt et al., 1980). The suspended solids from disturbed
sediment at project sites would settle out of the water column within a
few hours. Studies of the effects of turbid water on fish (marine
mammal prey) suggest that concentrations of suspended sediment can
reach thousands of milligrams per liter before an acute toxic reaction
is expected (Burton, 1993).
Effects from turbidity and sedimentation are expected to be short-
term, minor, and localized. Suspended solids in the water column should
dissipate and quickly return to background levels in all construction
scenarios. Turbidity within the water column has the potential to
reduce the level of oxygen in the water and irritate the gills of prey
fish species in the proposed project area. However, suspended sediment
associated with the project would be temporary and localized, and fish
in the proposed project area would be able to move away from and avoid
the areas where plumes may occur. Therefore, it is expected that the
impacts on prey fish species from turbidity, and therefore on marine
mammals, would be minimal and temporary. In general, the area likely
impacted by the proposed construction activities is relatively small
compared to the total available marine mammal habitat as well as the
critical habitat and the BIA in PWS. Therefore, we expect the impact
from increased turbidity levels to be discountable to marine mammals
and do not discuss it further.
In-water Effects on Potential Foraging Habitat--The proposed
activities would not result in permanent impacts to habitats used
directly by marine mammals and no increases in vessel traffic are
expected in either location as a result of the specified activities.
The areas likely impacted by the proposed actions are relatively small
compared to the total available habitat in PWS. The proposed project
areas are highly influenced by anthropogenic activities

[[Page 23830]]

and provide limited foraging habitat for marine mammals. The total
seafloor area affected by piling activities is small compared to the
vast foraging areas available to marine mammals at any of the proposed
construction sites. At best, the areas impacted provide marginal
foraging habitat for marine mammals and fishes. Furthermore, pile
driving at the project locations would not obstruct movements or
migration of marine mammals.
In-Water Effects on Potential Prey--Sound may affect marine mammals
through impacts on the abundance, behavior, or distribution of prey
species (e.g., crustaceans, cephalopods, fish, zooplankton, and other
marine mammals). Marine mammal prey varies by species, season, and
location. Here, we describe studies regarding the effects of noise on
known marine mammal prey.
Construction activities would produce continuous, non-impulsive
(i.e., vibratory pile driving, DTH) and intermittent impulsive (i.e.,
impact pile driving, DTH) sounds. Fish utilize the soundscape and
components of sound in their environment to perform important functions
such as foraging, predator avoidance, mating, and spawning (Zelick et
al., 1999; Fay, 2009). Depending on their hearing anatomy and
peripheral sensory structures, which vary among species, fishes hear
sounds using pressure and particle motion sensitivity capabilities and
detect the motion of surrounding water (Fay et al., 2008). The
potential effects of noise on fishes depends on the overlapping
frequency range, distance from the sound source, water depth of
exposure, and species-specific hearing sensitivity, anatomy, and
physiology. Key impacts to fishes may include behavioral responses,
hearing damage, barotrauma (pressure-related injuries), and mortality.
Fish react to sounds which 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 of which are
based on studies in support of large, multiyear bridge construction
projects (e.g., Scholik and Yan, 2001; Popper and Hastings, 2009). Many
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., Pearson et
al., 1992; Skalski et al., 1992; Santulli et al., 1999; Fewtrell and
McCauley, 2012; Paxton et al., 2017). In response to pile driving,
Pacific sardines (Sardinops sagax) and northern anchovies (Engraulis
mordax) may exhibit an immediate startle response to individual strikes
but return to ``normal'' pre-strike behavior following the conclusion
of pile driving with no evidence of injury as a result (see NAVFAC,
2014). However, some studies have shown no or slight reaction to
impulse sounds (e.g., Wardle et al., 2001; Popper et al., 2005;
Jorgenson and Gyselman, 2009; Pe[ntilde]a et al., 2013).
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. (2012b) showed that a TTS of 4-6 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., 2012a; Casper et al., 2013) and the greatest
potential effect on fish during the proposed project would occur during
impact pile driving, if it is required. However, the duration of impact
pile driving would be limited to a contingency in the event that
vibratory driving does not satisfactorily install the pile depending on
observed soil resistance. In-water construction activities would only
occur during daylight hours allowing fish to forage and transit the
project area at night. Vibratory pile driving may elicit behavioral
reactions from fish such as temporary avoidance of the area but is
unlikely to cause injuries to fish or have persistent effects on local
fish populations. In addition, it should be noted that the area in
question is low-quality habitat since it is already developed and
experiences anthropogenic noise from vessel traffic.
The most likely impact to fishes from pile driving and DTH
activities in the project areas would be temporary behavioral avoidance
of the area. The duration of fish avoidance of the area after pile
driving stops is unknown but a rapid return to normal recruitment,
distribution, and behavior is anticipated. There are times of known
seasonal marine mammal foraging when fish are aggregating but the
impacted areas are small portions of the total foraging habitats
available in the regions. In general, impacts to marine mammal prey
species are expected to be minor and temporary. Further, it is
anticipated that preparation activities for pile driving and DTH (i.e.,
positioning of the hammer) and upon initial startup of devices would
cause fish to move away from the affected area where injuries may
occur. Therefore, relatively small portions of the proposed project
area would be affected for short periods of time, and the potential for
effects on fish to occur would be temporary and limited to the duration
of sound[hyphen]generating activities.
Construction activities, in the form of increased turbidity, also
have the potential to adversely affect forage fish in the project area.
Pacific herring (Clupea pallasii) is a primary prey species of Steller
sea lions, humpback whales, and many other marine mammal species that
occur in the project areas. As discussed earlier, increased turbidity
is expected to occur in the immediate vicinity (approximately 25 ft
(7.6 m) or less) of construction activities (Everitt et al., 1980).
However, suspended solids are expected to dissipate quickly within a
single tidal cycle. Given the limited area affected and high tidal
dilution rates any effects on forage fish are expected to be minor or
negligible. In addition, best management practices would be in effect
to limit the extent of turbidity to the immediate project areas.
Finally, exposure to turbid waters from construction activities is not
expected to be different from the current exposure; fish and marine
mammals in the regions are routinely exposed to substantial levels of
suspended sediment from glacial sources.
In summary, given the short daily duration of sound associated with
pile driving and DTH, and the relatively small areas being affected,
pile driving and DTH activities associated with the proposed action are
not likely to have a permanent adverse effect on any fish habitat, or
populations of fish species. Thus, we conclude that impacts of the
specified activity are not likely to have more than short-term adverse
effects on any prey habitat or populations of prey species. Further,
any impacts to marine mammal habitat are not expected to result in
significant or long-term consequences for individual marine

[[Page 23831]]

mammals, or to contribute to adverse impacts on their populations.

Estimated Take of Marine Mammals

This section provides an estimate of the number of incidental takes
proposed for authorization through the IHAs, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use
of the acoustic sources (i.e., impact pile installation, vibratory pile
installation and removal, and DTH pile installation) has the potential
to result in disruption of behavioral patterns for individual marine
mammals. There is also some potential for AUD INJ (Level A harassment)
to result, primarily for low frequency cetaceans, very high frequency
cetaceans, phocids, and otariids because predicted AUD INJ zones are
larger than other high frequency cetaceans. AUD INJ is unlikely to
occur for other high frequency cetaceans. 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 criteria above which NMFS believes the best
available science indicates marine mammals will likely be behaviorally
harassed or incur some degree of AUD INJ; (2) the area or volume of
water that will be ensonified above these levels in a day; (3) the
density or occurrence of marine mammals within these ensonified areas;
and, (4) the number of days of activities. We note that while these
factors can contribute to a basic calculation to provide an initial
prediction of potential takes, additional information that can
qualitatively inform take estimates is also sometimes available (e.g.,
previous monitoring results or average group size). Below, we describe
the factors considered here in more detail and present the proposed
take estimates.

Acoustic Criteria

NMFS recommends the use of acoustic criteria 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 AUD INJ of some degree (equated to
Level A harassment). We note that the criteria for AUD INJ, as well as
the names of two hearing groups, have been recently updated (NMFS 2024)
as reflected below in the Level A harassment section.
Level B Harassment--Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g.,
scientific sonar) sources. Generally speaking, estimates of take by
Level B harassment 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.
ADOT&PF's proposed activity includes the use of continuous
(vibratory pile installation/removal and DTH pile installation) and
impulsive (impact pile driving and DTH pile installation) sources, and
therefore the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa is/are
applicable.
Level A Harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater marine
mammal groups (based on hearing sensitivity) as a result of exposure to
noise from two different types of sources (impulsive or non-impulsive).
ADOT&PF's proposed activity includes the use of impulsive (impact pile
installation and DTH pile installation) and non-impulsive (vibratory
pile installation/removal and DTH pile installation) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in table 6 below. The references, analysis, and
methodology used in the development of the criteria are described in
NMFS' 2024 Updated Technical Guidance, which may be accessed at:
<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>.

[[Page 23832]]

Table 6--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
AUD INJ Onset Acoustic Thresholds * (Received Level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 222 dB; Cell 2: LE,LF,24h: 197 dB
LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,HF,24h: 201 dB
LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,VHF,24h: 181 dB
LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 223 dB; Cell 8: LE,PW,24h: 195 dB
LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 230 dB; Cell 10: LE,OW,24h: 199 dB
LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [micro]Pa2s. In this table, criteria are abbreviated to be
more reflective of International Organization for Standardization (ISO) standards (ISO 2017; ISO 2020). The
subscript ``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within
the generalized hearing range of marine mammals underwater (i.e., 7 Hz to 165 kHz). The subscript associated
with cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting
function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is
24 hours. The weighted cumulative sound exposure level criteria 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 criteria 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 proposed project areas is the existing
background noise plus additional construction noise from the proposed
projects. Marine mammals are expected to be affected via sound
generated by the primary components of PWS Projects activities (i.e.,
pile installation and removal).
Sound Source Levels and TL of Proposed Activities--The intensity of
pile driving sounds is greatly influenced by factors such as the type
of piles (material and diameter), hammer type, and the physical
environment (e.g., sediment type) in which the activity takes place.
PWS Projects include vibratory pile installation and removal, impact
pipe pile installation, and DTH pile installation. ADOT&PF estimated
source levels and transmission loss coefficient measurements using
empirical measurements from similar activities elsewhere in Alaska or
outside of Alaska and relied on the best available and most relevant
sound source verification studies to determine appropriate proxy levels
for their proposed activities. Recently proposed and issued IHAs from
southeast Alaska were also reviewed to identify the most appropriate
proxy SPLs and TL coefficients. NMFS agrees that the SPL values and TL
coefficients that the ADOT&PF proposed are appropriate proxy levels for
their proposed activities (see table 7 for proposed proxy levels and
TLs). Source levels for vibratory removal of piles are assumed to be
the same as source levels for vibratory installation of piles of the
same diameter. Note that the values in table 7 and those discussed
herein represent SPL values referenced at a distance of 10 m from the
source.

Table 7--Summary of Unattenuated In-Water Pile Driving Proxy Levels (at 10 m) and Transmission Loss Coefficients
--------------------------------------------------------------------------------------------------------------------------------------------------------
RMS SPL (dB re 1 SEL (dB re 1 [mu]Pa2- Peak SPL (dB re 1 TL coefficient Relevant project
Pile size and type [mu]Pa) sec) [mu]Pa) (log10) Reference location
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile installation and removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
18-inch (46 cm) steel piles.... 161 N/A N/A 15 CALTRANS 2020..... Chenega, Cordova
20-inch (51 cm) steel piles.... 161 N/A N/A 15 CALTRANS 2020 Tatitlek
(cited in NMFS
2023).
24-inch (61 cm) steel piles.... 161 N/A N/A 15 CALTRANS 2020 All
(cited in NMFS
2023).
30-inch (76 cm) steel piles.... 166 N/A N/A 15 U.S. Navy 2015.... All
36-inch (91 cm) steel piles.... 166 N/A N/A 15 U.S. Navy 2015.... Tatitlek
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact pile installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm) steel piles.... 193 181 207 15 CALTRANS 2020 All
(cited in NMFS
2023) and U.S.
Navy 2015.
30-inch (76 cm) steel piles.... 193 184 211 15 U.S. Navy 2015.... All
36-inch (91 cm) steel piles... 193 184 211 15 U.S. Navy 2015.... Tatitlek
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 23833]]

DTH of rock sockets and tension anchors
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm) steel piles, 167 159 184 17 NMFS 2022; Reyff Chenega, Tatitlek
(rock socket). et al. 2025.
30- and 36-inch (76 and 91 cm) 174 164 194 17 NMFS 2022; Reyff Chenega, Tatitlek
steel piles (rock socket). et al. 2025.
8-inch (20 cm) tension anchors. 156 144 170 18 NMFS 2022; Reyff Chenega, Tatitlek
et al. 2025.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A means not applicable.

NMFS (2022) recommends that DTH system installation be treated as a
continuous sound source for Level B behavioral harassment calculations
and as an impulsive source for Level A harassment calculations given
these systems produce noise including characteristics of both source
types (described above in the Description of Sound Sources section).
Source levels proposed by ADOT&PF for all DTH pile installations match
those recommended by NMFS (2022), and thus are deemed acceptable by
NMFS as proxy levels for the proposed Projects. The TL coefficients
proposed by ADOT&PF for DTH pile installation differ from those
recommended by NMFS (2022), but for reasons explained below are
acceptable proxy TL coefficients for the proposed Projects.
TL data from the proposed Project sites or from areas with similar
physical and environmental conditions were not available for vibratory
pile installation, vibratory pile removal, and impact driving;
therefore, ADOT&PF proposed practical spreading (i.e., the default TL
coefficient of 15) as the proxy TL coefficient to determine distances
to the Level A harassment and Level B harassment thresholds for these
activities. For DTH and tension anchoring activities, ADOT&PF made
comparisons with Chenega and Tatitlek to other ferry terminal locations
where underwater sound source verification (SSV) studies have been
conducted in south central and southeast Alaska. Among the sites where
SSV studies have been conducted, it was determined that similar
environmental characteristics, including water temperature, substrate
type, and bathymetry were similar to the Chenega and Tatitlek project
sites. Data from Alaska DTH studies provide evidence that sounds from
drilling rock sockets for the pile sizes proposed in the PWS Projects
decay at a greater rate than practical spreading, with TL coefficients
from all but one study in Alaska ranging from an average of 15.5 to
19.5 (Reyff et al. 2025). Therefore, ADOT&PF proposed an average TL
coefficient of 17.0 for rock sockets.
Tension anchors of 8- to 10-inch (20 to 25 cm) diameter have been
measured throughout Alaska with variable results. Despite this,
underwater noise from tension anchor construction has typically been
low, possibly because the bedrock is overlain with sediments, which
together attenuate noise production from the drilling and reduce noise
propagation into the water column. Additionally, the casing used during
drilling is inside the larger-diameter pile, further reducing noise
levels. TL coefficients have ranged from 17 to 24, with a mean TL of
approximately 18 (J. Reyff, Pers. Coms.). For the proposed Projects,
ADOT&PF have proposed to use the TL coefficients for the DTH
installation of 8- to 10-inch (20 to 25 cm) tension anchors. Due to the
similarity in site characteristics of the proposed PWS Projects and the
measured TL coefficients, NMFS concurs that ADOT&PF's proposed TL
coefficients for DTH pile installation are acceptable as proxy
coefficients for the proposed Projects.
Estimated Harassment Isopleths--All estimated Level B harassment
isopleths are reported in table 11. At all proposed Project sites,
Level B harassment isopleths would be truncated by the surrounding
coastlines and certain bathymetric features (e.g., mud flats exposed
during low tides).
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 2024 Updated Technical Guidance that
can be used to relatively simply predict an isopleth distance for use
in conjunction with marine mammal density or occurrence to help predict
potential takes. We note that because of some of the assumptions
included in the methods underlying this optional tool, we anticipate
that the resulting isopleth estimates are typically going to be
overestimates of some degree, which may result in an overestimate of
potential take by Level A harassment. However, this optional tool
offers the best way to estimate isopleth distances when more
sophisticated modeling methods are not available or practical. For
stationary sources such as pile driving, the optional User Spreadsheet
tool predicts the distance at which, if a marine mammal remained at
that distance for the duration of the activity, it would be expected to
incur AUD INJ.
To account for potential variations in daily productivity during
DTH pile installation, ADOT&PF calculated ensonified areas for Level A
harassment were for different durations of installation, ranging from
60 minutes minimum up to 480 minutes for rock sockets, and from 60
minutes to 240 minutes for tension anchors. For vibratory installation,
harassment zones were calculated based on the maximum number of piles
and duration for any given day for contactor flexibility.
The pulse rate or frequency for DTH pile installation is generally
negatively correlated with borehole diameter but varies by the
equipment used. ADOT&PF have estimated that rock socket boreholes would
be constructed by equipment operating at approximately 15 Hz, or 15
cycles per second, which is equivalent to 900 strikes per minute. Due
to the smaller diameter of tension anchor boreholes, ADOT&PF have
estimated that a strike rate of 30 Hz (30 cycles per second) is
appropriate for the DTH installation of tension anchors.
ADOT&PF estimate that impact installation of all pile sizes would
require 50 strikes per pile for proofing; however, this may vary based
on the embedment. At Cordova Ferry Terminal, where the use of DTH
methods is not anticipated, full impact installation of permanent piles
is estimated to be 600 strikes per pile. Inputs used in the optional
User Spreadsheet tool, and the

[[Page 23834]]

resulting estimated isopleths, are reported in tables 8, 9, 10, and 11.

Table 8--NMFS User Spreadsheet Inputs for the Cordova Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Weighting Transmission Activity Number of Number of Distance of sound
Pile diameter Spreadsheet tab Source level factor loss duration strikes per piles per pressure level
used (SPL) adjustment coefficient (minutes) pile day measurement (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm)............. A.1) Vibratory 161 dB RMS..... 2.5 15 30 N/A 4 10
Pile Driving.
30-inch (76 cm)............. 166 dB RMS..... 2.5 15 60 N/A 2 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
18-inch (46 cm)............. A.1) Vibratory 161 dB RMS..... 2.5 15 60 N/A 4 10
Pile Driving.
24-inch (61 cm)............. 161 dB RMS..... 2.5 15 30 N/A 4 10
30-inch (76 cm)............. 166 dB RMS..... 2.5 15 60 N/A 3 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
30-inch (76 cm)............. E.1) Impact 184 dB SEL..... 2 15 N/A 600 1, 2 10
Pile driving.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A means not applicable.

Table 9--NMFS User Spreadsheet Inputs for the Chenega Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of
strikes per
Spreadsheet tab Weighting Transmission Activity pile Number of Distance of sound
Pile diameter used Source level factor loss duration (impact) or piles per pressure level
adjustment coefficient (minutes) strike rate day measurement (m)
(DTH)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
18-inch (46 cm)............. A.1) Vibratory 161 dB RMS..... 2.5 15 15 N/A 2 10
Pile Driving.
24-inch (61 cm)............. 161 dB RMS..... 2.5 15 15 N/A 4 10
30-inch (76 cm)............. 166 dB RMS..... 2.5 15 15 N/A 4 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm)............. A.1) Vibratory 161 dB RMS..... 2.5 15 30 N/A 4 10
Pile Driving.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm)............. E.1) Impact 181 dB SEL..... 2 15 N/A 50 2 10
Pile driving.
30-inch (76 cm)............. 184 dB SEL..... 2 15 N/A 50 2 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH (rock socket)
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm)............. E.2) DTH 159 dB SEL..... 2 17 60 15 1 10
Systems.
159 dB SEL..... 2 17 120 15 1 10
159 dB SEL..... 2 17 240 15 1 10
159 dB SEL..... 2 17 360 15 1 10
159 dB SEL..... 2 17 480 15 1 10
30-inch (76 cm)............. 164 dB SEL..... 2 17 60 15 1 10
164 dB SEL..... 2 17 120 15 1 10
164 dB SEL..... 2 17 240 15 1 10
164 dB SEL..... 2 17 360 15 1 10
164 dB SEL..... 2 17 480 15 1 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH (tension anchor)
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-inch (20 cm).............. E.2) DTH 144 dB SEL..... 2 18 60 15 1 10
Systems.
144 dB SEL..... 2 18 120 15 1 10
144 dB SEL..... 2 18 180 15 1 10
144 dB SEL..... 2 18 240 15 1 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A means not applicable.

[[Page 23835]]

Table 10--NMFS User Spreadsheet Inputs for the Tatitlek Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of
strikes per
Spreadsheet tab Source level Weighting Transmission Activity pile Number of Distance of sound
Pile diameter used (SPL) factor loss duration (impact) or piles per pressure level
adjustment coefficient (minutes) strike rate day measurement (m)
(DTH)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch (61 cm)............. A.1) Vibratory 161 dB RMS..... 2.5 15 15 N/A 4 10
Pile Driving.
30-inch (76 cm)............. 166 dB RMS..... 2.5 15 15 N/A 1 10
36-inch (91 cm)............. 166 dB RMS..... 2.5 15 15 N/A 1 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
20-inch (51 cm)............. A.1) Vibratory 161 dB RMS..... 2.5 15 60 N/A 3 10
Pile Driving.
24-inch (61 cm)............. 161 dB RMS..... 2.5 15 30 N/A 4 10
30-inch (76 cm)............. 166 dB RMS..... 2.5 15 60 N/A 4 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
30-inch (76 cm)............. E.1) Impact 184 dB SEL..... 2 15 N/A 50 1 10
Pile driving.
30-inch (76 cm)............. 184 dB SEL..... 2 15 N/A 50 1 10
36-inch (91 cm)............. 184 dB SEL..... 2 15 N/A 50 1 10
36-inch (91 cm)............. 184 dB SEL..... 2 15 N/A 50 1 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH (rock socket)
--------------------------------------------------------------------------------------------------------------------------------------------------------
30-inch (76 cm)............. E.2) DTH 164 dB SEL..... 2 17 60 15 1 10
Systems.
164 dB SEL..... 2 17 120 15 1 10
164 dB SEL..... 2 17 240 15 1 10
164 dB SEL..... 2 17 360 15 1 10
164 dB SEL..... 2 17 480 15 1 10
36-inch (91 cm)............. 164 dB SEL..... 2 17 60 15 1 10
164 dB SEL..... 2 17 120 15 1 10
164 dB SEL..... 2 17 240 15 1 10
164 dB SEL..... 2 17 360 15 1 10
164 dB SEL..... 2 17 480 15 1 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH (tension anchor)
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-inch (20 cm).............. ............... 144 dB SEL..... 2 18 60 15 1 10
144 dB SEL..... 2 18 120 15 1 10
144 dB SEL..... 2 18 180 15 1 10
144 dB SEL..... 2 18 240 15 1 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A means not applicable.

[[Page 23836]]

Table 11--Calculated Distances and Areas of Level A and Level B Harassment per Pile Type and Pile Driving Method
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment isopleth, by hearing group (m) Level B Level B harassment area (km2;
Activity ------------------------------------------------------- harassment all hearing groups)\1\
Activity Pile diameter duration Strikes per Piles per distance (m; --------------------------------
(inches) (min) pile day LF HF VHF PW OW all hearing
groups) Cordova Chenega Tatitlek
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation......... 18-inch (46 cm)... 15 N/A 2 5.8 2.2 4.7 7.5 2.5 5,412 N/A 11.84 N/A
24-inch (61 cm)... 15 4 9.2 3.5 7.5 11.9 4 N/A 11.84 20.90
30 4 14.6 5.6 12.0 18.8 6.3 22.33 N/A N/A
30-inch (76 cm)... 15 2 12.5 4.8 10.2 16.1 5.4 11,659 N/A N/A 50.35
15 4 19.9 7.6 16.2 25.6 8.6 N/A 12.98 N/A
60 4 31.5 12.1 25.8 40.6 13.7 52.22 N/A N/A
36-inch (91 cm)... 15 2 12.5 4.8 10.2 16.1 5.4 N/A N/A 50.35
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Removal.............. 18-inch (46 cm)... 60 4 23.2 8.9 19.0 29.9 10.1 5,412 22.33 N/A N/A
20-inch (51 cm)... 60 3 19.2 7.4 15.7 24.7 8.3 N/A 20.90
24-inch (61 cm)... 30 4 14.6 5.6 12.0 18.8 6.3 11.84 20.90
30-inch (76 cm)... 60 3 41.3 15.9 33.8 53.2 17.9 11,659 52.22 N/A N/A
4 50.1 19.2 40.9 64.4 21.7 N/A N/A 62.38
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Installation............ 24-inch (61 cm)... N/A 50 2 157.7 20.1 244.0 140.1 52.2 1,585 N/A 3.80 N/A
30-inch (76 cm)... 50 2 249.9 31.9 386.8 222.0 82.8 N/A 3.80 N/A
600 1 825.3 105.3 1,277.1 733.1 273.3 3.95 N/A N/A
2 1,310.0 167.1 2,027.3 1,163.8 433.8
36-inch (91 cm)... 50 1 157.4 20.1 243.7 139.9 52.1 N/A N/A 5.14
20 2 249.9 31.9 386.8 222.0 82.8
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
DTH rock socket................ 24-inch (61 cm)... 60 N/A N/A 234.5 38.1 344.7 211.2 88.4 5,817 N/A 12.17 N/A
120 352.5 57.3 518.3 317.5 132.9
240 529.9 86.1 779.0 477.4 199.9
360 672.7 109.4 988.9 606.0 253.7
480 796.7 129.5 1,171.2 717.7 300.5
----------------------------------------------------------------------------------------------------------------------------------------------------------------
30-inch (76 cm)... 60 N/A N/A 461.5 75.0 678.4 415.7 174.1 15,013 N/A 12.98 62.38
120 693.9 112.8 1,020.0 625.0 261.7
----------------------------------------------------------------------------------------------------------------------------------------------------------------
240 1,043.1 169.6 1,533.4 939.7 393.4
360 1,324.1 215.2 1,946.5 1,192.8 499.4
480 1,568.3 254.9 2,305.4 1,412.7 591.4
----------------------------------------------------------------------------------------------------------------------------------------------------------------
36-inch (76 cm)... 60 N/A N/A 461.5 75.0 678.4 415.7 174.1 15,013 N/A 12.98 62.38
120 693.9 112.8 1,020.0 625.0 261.7
240 1,043.1 169.6 1,533.4 939.7 393.4
360 1,324.1 215.2 1,946.5 1,192.8 499.4
480 1,568.3 254.9 2,305.4 1,412.7 591.4
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
DTH (tension anchor)........... 8-inch (20 cm).... 60 N/A N/A 42.4 7.6 61.1 38.5 16.9 1,000 N/A 1.92 2.28
120 53.2 9.6 76.5 48.2 21.2
180 62.4 11.2 89.8 56.5 24.8
240 91.7 16.5 131.9 83.1 36.5
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\Level B harassment areas vary by location based on the local topographies.
Note: N/A means not applicable. km\2\ = square kilometer.

[[Page 23837]]

Marine Mammal Occurrence and Take Estimation

In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations. Available information regarding
marine mammal occurrence in the vicinity of the project area includes
site-specific and nearby survey information, historic data sets, and
observations from local residents at each project site. In particular,
ADOT&PF gathered qualitative information from discussions with
knowledgeable local people in the Cordova, Chenega, and Tatitlek
communities, including individuals familiar with marine mammals in the
Project areas. NMFS disagrees with some of the occurrence estimates
proposed by ADOT&PF, and has provided explanations and adjusted
estimates below for each species. Tables 12 and 13 show the occurrence
estimates requested by ADOT&PF and the adjusted occurrence estimates
used by NMFS in our take estimation calculations.
Humpback whale--Humpback whales are rarely observed around Cordova,
with residents describing a small number of sightings annually.
However, to account for the potential for a higher than normal
abundance of humpback whales to occur during the 33 construction days
(approximately six 5-day work weeks), ADOT&PF estimated up to two
humpback exposures per construction week. NMFS concurs with this
estimate.
Humpback whales are occasionally observed around Chenega, with
residents describing a small number of sightings annually, typically in
groups of two to five individuals. To account for the potential for a
higher than normal abundance of humpback whales occur during the
project, ADOT&PF estimated up to five humpback exposures per
construction week of the Chenega Project. NMFS disagrees with this
estimate, noting that a few sightings annually would not equate to five
individuals per week. NMFS proposes to authorize exposures of up to two
individuals per week for the estimated 12 weeks of construction.
Humpback whales are occasionally observed around Tatitlek, with
residents describing a small number of sightings annually. However, to
avoid shutdowns should a higher than normal abundance of humpback
whales occur during the project, ADOT&PF estimated that up to two
humpbacks may be exposed per week; NMFS concurs with this estimate.
Minke whale--Local residents reported that no minke whales have
been observed near Cordova, Chenega, or Tatitlek. To account for the
potential for a higher than average minke whale abundance occur during
the construction window, ADOT&PF estimated that up to two minke whales
could occur within each project area over the entire duration of each
project. NMFS concurs with these estimates.
Killer whale--Killer whales have been monitored in PWS since the
1989 Exxon Valdez oil spill, with regular observations near Cordova
(Matkin et al. 2013), and a reasonable likelihood of occurrence near
Chenega and Tatitlek. ADOT&PF estimates that one pod of 15 resident
animals, or multiple smaller pods of transient animals totaling 15
animals, may transit through each project area during each month of
construction. NMFS concurs with this estimate. Specific to AT1
Transient stock, NMFS considers any exposure of AT1 whales would likely
be of a group, here assumed to consist of 7 individuals. NMFS considers
it reasonably likely that AT1 whales may occur one time during the
course of the project at each project site.
Pacific white-sided dolphin--Most observations of Pacific white-
sided dolphins occur off the outer coast or in inland waterways near
entrances to the open ocean (Muto et al. 2021). Irregular sightings
indicate that there is a small potential for Pacific white-sided
dolphins to occur in the Project areas. However, recent fluctuations in
distribution and abundance decrease the certainty in this prediction.
ADOT&PF therefore estimated that one large group (92 individuals based
on the median of groups between 20 and 164 individuals) (Muto et al.
2018) of Pacific white-sided dolphins may occur in each project area
over the duration of the in-water construction period.
Dall's porpoise--Sightings of Dall's porpoises throughout PWS were
not described by local residents. At Tatitlek, however, an unidentified
porpoise was described as occurring in deeper, open water. As such,
there is limited potential for Dall's porpoises to occur in the project
areas. Recent research indicates that Dall's porpoises may
opportunistically exploit nearshore habitats when predators, such as
killer whales, are absent (Moran et al. 2018). Based on knowledge of
Dall's porpoise abundance in PWS, ADOT&PF estimated that two pods of up
to 10 individuals (or 20 individuals total) may transit the each
project site during each month of in-water construction. NMFS disagrees
with the estimates of group size and frequency based on the highest
average seasonal group size (4.8 individuals, winter) and encounter
rates in PWS (Moran et al. 2018), and instead proposes that four groups
of 5 individuals may transit each project site each month.
Harbor porpoise--Sightings of harbor porpoises throughout PWS were
not described by local residents, except at Chenega, where residents
report seeing bow-riding harbor porpoises, but mostly in the open
waters away from the project area. At Tatitlek, an unidentified
porpoise was described as occurring in deeper, open water. As such,
there is limited potential for harbor porpoise to occur in the project
areas in low numbers. ADOT&PF therefore estimated that up to two harbor
porpoises per day could occur in each of the project areas. NMFS
disagrees with this estimate because in the absence of definitive
sightings by local residents an estimate of two porpoises per day is
not reasonably likely. However, this species is small, cryptic, and can
be difficult to detect. NMFS therefore conservatively estimates that
one group of two porpoises could occur every other day at each project
location.
Harbor seal--Harbor seals are commonly sighted throughout PWS and
along the North Gulf Coast included in this region. The Alaska
Fisheries Science Center identified ``key'' haulouts (haulouts that
have had 50 or more harbor seals documented during surveys) within a
10-mile radius of the project areas: 17 at Cordova, 12 at Chenega; and
two at Tatitlek (NOAA 2021). NMFS aerial survey data between 2006 and
2015 indicate that as many as 348 harbor seals were sighted near
Cordova (Area GG08, NOAA 2022), between 86 and 531 near Chenega (Area
HF21, NOAA 2022), and up to 10 near Tatitlek (Area GG08, NOAA 2022).
However, local residents report that only small numbers of harbor seals
are regularly observed near the project areas: one to two near Cordova;
two to five near Chenega; and two to five near Tatitlek. In Cordova,
these individuals are generally observed monthly near the ferry
terminal, with lower sightings during the winter months, while in
Chenega and Tatitlek, residents noted that harbor seals are observed
weekly throughout the year, and more frequently observed during herring
and salmon runs in spring and summer.
ADOT&PF estimated that up to four harbor seals could be present
each day at Cordova and Chenega, and up to five harbor seals per day at
Tatitlek. NMFS concurs with the estimates for Chenega and Tatitlek
based on local resident knowledge, and disagrees with the estimate for
Cordova. Group sizes at

[[Page 23838]]

Cordova were cited as one to two individuals observed monthly; thus, an
estimate of four animals per day is not reasonably likely to occur.
NMFS instead proposes that up to two individuals may be present per day
at Cordova.
Steller sea lions--Steller sea lions are uncommon in the Cordova
Project area. The nearest documented haulout is Hook Point, about 35.7
km (22.2 miles) southwest of Cordova on Hinchinbrook Island. Up to 70
Steller sea lions were present during aerial surveys over Hook Point
that occurred between 2013 and 2019 (Sweeney et al. 2019). However,
local residents report that Steller sea lions can often be seen on
buoys around 3 km (1.9 miles) from the Cordova Project area (one to two
individuals at a time) and in nearby waters (four to five individuals),
with greater presence during hooligan and salmon runs in spring,
summer, and fall. ADOT&PF estimated that a group of 10 Steller sea
lions could transit the Cordova project area every day. NMFS disagrees
with this estimate based on the resident reports of a maximum of five
individuals per group, and instead proposes that up to five Steller sea
lions could be in the Cordova project area each day of construction.
Steller sea lions are common in the Chenega project area with
systematic counts or surveys completed by NMFS in the area around
Chenega identifying multiple haulouts within 15 miles of the harbor.
The nearest documented haulout is Point LaTouche, about 14 km (8.6
miles) southwest of Chenega. No Steller sea lions were present during
aerial surveys over Point LaTouche that occurred between 2013 and 2021
(Fritz et al. 2016; Sweeney et al.2017; Sweeney et al. 2019; Sweeney et
al. 2021). Other sites within 15 miles of Chenega harbor--Danger
Island, Point Elrington, and Procession Rocks--had 305 sea lions
observed, four of which were pups at Procession Rocks (Sweeney et al.
2021). Local residents report observing groups of Steller sea lions
year-round (3 to 5 individuals), with a particularly high presence (up
to 40 individuals) during the late summer and early fall salmon runs.
ADOT&PF conservatively estimated that an average of up to 20 Steller
sea lions could transit the Chenega Project area every day. NMFS
disagrees with this estimate, based on resident reports of up to 40
individuals only during late summer, and a much smaller group size
(three to five animals) during the remainder of the year. NMFS proposes
that a reasonably likely annual average for this project site is 10
Steller sea lions per day.
Steller sea lions are uncommon in the Tatitlek project area. The
nearest documented haulout is Glacier Island, about 25.9 km (16.1
miles) southwest of Tatitlek. Recent surveys documented 821 Steller sea
lions and 20 Steller sea lion pups during aerial surveys over Glacier
Island that occurred in 2019 (Sweeney et al. 2019). Steller sea lion
presence was reported to be higher during spring and summer, with
groups as large as 6 to 10 individuals. ADOT&PF conservatively
estimated that one group of 10 Steller sea lions could transit the
Tatitlek project area every day. NMFS disagrees with this estimate,
based on the range of group sizes reported by residents, and instead
proposes that the minimum number cited be used as the daily average,
resulting in up to six Steller sea lions per day in the Tatitlek
project area.

Table 12--Species Occurrence Estimates as Proposed by ADOT and Adjusted by NMFS
----------------------------------------------------------------------------------------------------------------
Proposed by ADOT NMFS adjusted
-----------------------------------------------------------------------------------
Species Group Group Reason for
size Frequency Reference size Frequency change
----------------------------------------------------------------------------------------------------------------
Cordova
----------------------------------------------------------------------------------------------------------------
Harbor porpoise............. 2 Daily.......... No local 2 Every other Day No local
reports. reports, but
possible that
small cryptic
species could
be present and
unobserved on
an irregular
basis.
Dall's porpoise............. 10 2x monthly..... Known to occur 5 4x Monthly..... Moran et al.
throughout PWS (2018) shows
in groups of 1- maximum
10 individuals. average group
size of 4.82
during winter
in PWS, and
frequently
encountered
throughout
PWS.
Steller sea lion............ 10 Daily.......... Regular 5 Daily.......... Maximum daily
sightings of 1 sightings of
to 5 5.
individuals in
spring,
summer, and
fall.
Harbor seal................. 4 Daily.......... Regular 2 Daily.......... Maximum
sightings of 1- sightings of 2
2 individuals individuals on
monthly. a monthly
basis; 2 per
day is more
reasonable.
----------------------------------------------------------------------------------------------------------------
Chenega
----------------------------------------------------------------------------------------------------------------
Humpback whale.............. 5 1x/week........ Occasional 2 1x/week........ Use minimum
local group size for
sightings of 2- ``occasional''
5 individuals. sightings, vs.
max of 5.
Harbor porpoise............. 2 Daily.......... No local 2 Every other Day No local
reports. reports, but
possible that
small cryptic
species could
be present and
unobserved on
an irregular
basis.
Dall's porpoise............. 10 2x monthly..... Known to occur 5 4x Monthly..... Moran et al.
throughout PWS (2018) shows
in groups of 1- maximum
10 individuals. average group
size of 4.82
during winter
in PWS, and
frequently
encountered
throughout
PWS.

[[Page 23839]]

Steller sea lion............ 20 Daily.......... Regular 10 Daily.......... Regular
sightings of 3 sightings of
to 5 up to 5, with
individuals occasional
year round; up much larger
to 40 during groups; 10 per
summer salmon day is likely
runs. a reasonable
average.
----------------------------------------------------------------------------------------------------------------
Tatitlek
----------------------------------------------------------------------------------------------------------------
Harbor porpoise............. 2 1x/day......... No local 2 Every other Day No local
reports. reports, but
possible that
small cryptic
species could
be present and
unobserved on
an irregular
basis,
Dall's porpoise............. 10 2x monthly..... Known to occur 5 4x Monthly..... Moran et al.
throughout PWS (2018) shows
in groups of 1- maximum
10 individuals. average group
size of 4.82
during winter
in PWS, and
frequently
encountered
throughout
PWS.
Steller sea lion............ 10 Daily.......... Sightings of 6 6 Daily.......... Annual average
to 10 is likely
individuals in fewer than 10
summer. individuals
per day; 6 is
reasonable.
----------------------------------------------------------------------------------------------------------------

Table 13--Proposed Species Occurrences at All Three Project Locations
----------------------------------------------------------------------------------------------------------------
Group size
Species Frequency ------------------------------
Cordova Chenega Tatitlek
----------------------------------------------------------------------------------------------------------------
Humpback whale................................ 1x/week.......................... 2 2 2
Minke whale................................... 1x/year.......................... 2 2 2
Killer whale.................................. 1x/month......................... 15 15 15
Pacific white-sided dolphin................... 1x/year.......................... 92 92 92
Harbor porpoise............................... Every other Day.................. 2 2 2
Dall's porpoise............................... 4x/month......................... 5 5 5
Steller sea lion.............................. Daily............................ 5 10 6
Harbor seal................................... Daily............................ 2 4 5
----------------------------------------------------------------------------------------------------------------

Take Estimation

Here we describe how occurrence information is synthesized to
produce a quantitative estimate of the take that is reasonably likely
to occur and proposed for authorization for each project. Take was
estimated based on the estimated species group size and frequency, as
well as the best estimate of the number of days proposed for each
activity, and, for some species, the predicted ensonified areas for
each activity.
Total exposures for each species at each location was calculated
using the occurrence estimates shown in table 13, multiplied by the
best estimate of work duration at each project location (tables 1
through 3). Estimated take by Level B harassment was calculated as the
total exposures minus the estimated take by Level A harassment.
Estimated take by Level A harassment for species that are relatively
common at the project sites (i.e., Steller sea lion, harbor seal,
harbor porpoise, and humpback whale) was calculated based on the ratio
of the maximum Level A harassment area to the maximum Level B
harassment area for each site (table 14). For pinnipeds and VHF
cetacean species, the area of the proposed shutdown zone was subtracted
from the area of the Level A harassment zone.

Table 14--Areas and Calculated Ratios for Estimating Take by Level A
Harassment for Four Species
------------------------------------------------------------------------
Steller Harbor Harbor Humpback
sea lion seal porpoise whale
------------------------------------------------------------------------
Cordova
------------------------------------------------------------------------
Shutdown zone area (km\2\).... 0.1413 0
-----------------------------------------
Level A area (km\2\).......... 0.33 2.285 na 2.8
-----------------------------------------
Level B area (km\2\).......... 3.95
-----------------------------------------
Ratio......................... 0.048 0.543 na 0.709
------------------------------------------------------------------------

[[Page 23840]]

Chenega
------------------------------------------------------------------------
Shutdown zone area (km\2\).... 0.21195 0
-----------------------------------------
Level A area (km\2\).......... 0.77 3.2 5.5 3.75
-----------------------------------------
Level B area (km\2\).......... 12.975
-----------------------------------------
Ratio......................... 0.043 0.016 0.408 0.289
------------------------------------------------------------------------
Tatitlek
------------------------------------------------------------------------
Shutdown zone area (km\2\).... 0.21195 0
-----------------------------------------
Level A area (km\2\).......... 0.499 2.6 6 3.2
-----------------------------------------
Level B area (km\2\).......... 62.375
-----------------------------------------
Ratio......................... 0.005 0.038 0.093 0.051
------------------------------------------------------------------------

For the remaining species, which are uncommon at the project
locations, estimated take by Level A harassment was either not
considered likely due to low occurrence estimates and historical
sighting data (i.e., Pacific white-sided dolphin, minke whale) or high
visibility of the species (i.e., killer whale), or was adjusted based
on average group size (i.e., Dall's porpoise).
Total exposures and proposed take by Level A and Level B harassment
at Cordova, Chenega, and Tatitlek are shown in tables 15, 16, and 17,
respectively.

Table 15--Proposed Take of Marine Mammals by Level A and Level B Harassment and Percent of Stock Proposed To Be
Taken at the Cordova Project
----------------------------------------------------------------------------------------------------------------
Percent of
Species Stock Level A Level B Total stock
----------------------------------------------------------------------------------------------------------------
Steller sea lion......................... Western North Pacific....... 1 299 300 0.6
Harbor seal.............................. Prince William Sound........ 3 117 120 0.27
Harbor porpoise.......................... Gulf of Alaska.............. 56 4 60 0.19
Dall's porpoise.......................... Alaska...................... 10 30 40 \a\ UND
Pacific white-sided dolphin.............. North Pacific............... 0 92 92 0.34
Killer whale \b\......................... Alaska Resident............. 0 30 30 1.56
AT1 Transient............... n/a
Northern Resident........... 9.93
West Coast Transient........ 8.6
Humpback whale........................... Hawaii...................... 5 10 15 0.13
Mexico-North Pacific........ 0 2 2 \a\ UND
Minke whale.............................. Alaska...................... 0 2 2 \a\ UND
----------------------------------------------------------------------------------------------------------------
\a\ Stock size is undetermined.
\b\ NMFS conservatively assumes that all takes may come from any stock, thus these numbers represent
overestimates if multiple stocks occur. See discussion in Small Numbers section.

Table 16--Proposed Take of Marine Mammals by Level A and Level B Harassment and Percent of Stock Proposed To Be
Taken at the Chenega Project
----------------------------------------------------------------------------------------------------------------
Percent of
Species Stock Level A Level B Total stock
----------------------------------------------------------------------------------------------------------------
Steller sea lion......................... Western North Pacific....... 63 1497 1560 3.13
Harbor seal.............................. Prince William Sound........ 10 614 624 1.39
Harbor porpoise.......................... Gulf of Alaska.............. 120 36 156 0.50
Dall's porpoise.......................... Alaska...................... 50 50 100 \a\ UND
Pacific white-sided dolphin.............. North Pacific............... 0 92 92 0.34
Killer whale \b\......................... Alaska Resident............. 0 75 75 4.47
AT1 Transient............... n/a
Northern Resident........... 24.7
West Coast Transient........ 30.1
Humpback whale........................... Hawaii...................... 11 29 40 0.35
Mexico-North Pacific........ 1 4 5 \a\ UND

[[Page 23841]]

Minke whale.............................. Alaska...................... 0 0 2 \a\ UND
----------------------------------------------------------------------------------------------------------------
\a\ Stock size is undetermined.
\b\ NMFS conservatively assumes that all takes may come from any stock, thus these numbers represent
overestimates if multiple stocks occur. See discussion in Small Numbers section.

Table 17--Proposed Take of Marine Mammals by Level A and Level B Harassment and Percent of Stock Proposed To Be
Taken at the Tatitlek Project
----------------------------------------------------------------------------------------------------------------
Percent of
Species Stock Level A Level B Total stock
----------------------------------------------------------------------------------------------------------------
Steller sea lion......................... Western North Pacific....... 4 452 456 0.91
Harbor seal.............................. Prince William Sound........ 24 356 380 0.85
Harbor porpoise.......................... Gulf of Alaska.............. 12 64 76 0.24
Dall's porpoise.......................... Alaska...................... 40 40 80 \a\ UND
Pacific white-sided dolphin.............. North Pacific............... 0 92 92 0.34
Killer whale \b\......................... Alaska Resident............. 0 60 60 3.13
AT1 Transient............... n/a
Northern Resident........... 19.9
West Coast Transient........ 17.2
Humpback whale........................... Hawaii...................... 9 11 20 0.18
Mexico-North Pacific........ 1 1 2 \a\ UND
Minke whale.............................. Alaska...................... 0 2 2 \a\ UND
----------------------------------------------------------------------------------------------------------------
\a\ Stock size is undetermined.
\b\ NMFS conservatively assumes that all takes may come from any stock, thus these numbers represent
overestimates if multiple stocks occur. See discussion in Small Numbers section.

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. 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, as
well as subsistence uses. 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.
ADOT&PF must ensure that construction supervisors and crews, the
monitoring team and relevant ADOT&PF staff are trained prior to the
start of all pile driving and DTH activities, so that responsibilities,
communication procedures, monitoring protocols, and operational
procedures are clearly understood. New personnel joining during the
project must be trained prior to commencing work.

Protected Species Observers

ADOT&PF must employ NMFS-approved protected species observers
(PSOs), who are independent of the construction contractor, and
establish monitoring locations as described in the NMFS-approved Marine
Mammal Monitoring Plans and Section 5 of the three PWS Project IHAs.
ADOT&PF must monitor the project areas to the maximum extent possible
based on monitoring locations and environmental conditions. If
environmental conditions deteriorate such that the entirety of shutdown
zones would not be visible (e.g., fog, heavy rain, Beaufort sea state,
etc.), all pile driving would be delayed until PSOs are confident that
marine mammals in the shutdown zones could be detected. For each of PWS
Project sites, ADOT&PF must employ at least two PSOs for vibratory pile
driving and removal, impact pile driving and DTH. The placement of the
PSOs during all pile driving and removal and DTH activities will ensure
that the entire shutdown zone is visible.

Pre- and Post-Activity Monitoring

Prior to the start of daily in-water construction activities, or
whenever a break in pile driving of 30 minutes or longer occurs, PSOs
would observe shutdown and monitoring zones for a 30 minutes (pre-
clearance monitoring) through 30 minutes post-completion of pile
driving or DTH activities. Pre-clearance monitoring must be conducted
during periods of visibility sufficient for the lead PSO to determine
that the shutdown zones indicated in tables 18 through 20 are clear of
marine mammals.

[[Page 23842]]

Soft-Start Procedures for Impact Driving

Soft-start procedures provide additional protection to marine
mammals by providing warning and/or giving marine mammals a chance to
leave the area prior to the hammer operating at full capacity. ADOT&PF
must use soft start techniques when impact pile driving. Soft start
requires contractors to provide an initial set of three strikes at
reduced energy, followed by a 30-second waiting period, then two
subsequent reduced-energy strike sets. A soft start must be implemented
at the start of each day's impact pile driving and at any time
following cessation of impact pile driving for a period of 30 minutes
or longer.

Shutdown Zones

Prior to the start of any in-water construction, ADOT&PF would
establish shutdown zones for pile driving/removal and DTH activities.
The purpose of a shutdown zone is to define an area within which
construction would be delayed or halted upon sightings of a marine
mammal in that defined area or in anticipation of a marine mammal
entering that area. After construction is delayed or halted, pile
driving/removal or DTH would not re-commence until marine mammals have
cleared these established shutdown zones or have not been sighted for
at least 15 minutes. Generally, shutdown zones vary in size based upon
the activity type, duration, and the marine mammal hearing group. In
most cases, shutdown zones are based on the estimated Level A
harassment isopleth distances for each hearing group. However, in cases
where ADOT&PF asserted that it would be impracticable to shut down at
the Level A harassment isopleth due to excessive work stoppages,
smaller shutdown zones are proposed. ADOT&PF's proposed shutdown zones
would be smaller than Level A harassment zones for impact driving 30-
inch (76 centimeters (cm)) piles at all PWS Project sites, DTH rock
socketing for 24-inch (61 cm) piles at Chenega, impact driving and DTH
rock socketing of 36-inch (91 cm) piles at Tatitlek, and DTH rock
socketing for 30-inch (76 cm) piles at both Chenega and Tatitlek.
ADOT&PF anticipates that the maximum amount of activity within a
given day may vary significantly at all PWS project sites. Given this
uncertainty, ADOT&PF proposed a tiered system of shutdown zones for
marine mammal hearing groups. This tiered system is based on the
maximum expected number of piles to be installed (impact or vibratory
pile driving) or the maximum expected DTH duration in a given day. At
the start of each work day, ADOT&PF would determine the maximum
scenario possible for that day (according to the defined duration
intervals in tables 8 through 10), which will determine the appropriate
Level A harassment isopleth and associated shutdown zone for that day.
This Level A harassment zones (table 11) and associated shutdown zones
(tables 18 through 20) must be implemented for the entire work day.
Additionally, in order to minimize the potential for impacts to the
depleted AT1 stock of killer whales, ADOT&PF proposes to shut down at
the estimated Level B harassment zone for any killer whales sighted
during impact pile driving at all sites.
The placement of PSOs during all pile installation and removal, and
DTH activities (described in detail in the Proposed Monitoring and
Reporting section) will ensure that the entire shutdown zones are
visible during pile installation. If a marine mammal is observed
entering or within the shutdown zones indicated in tables 18 through
20, pile driving must be delayed or halted. If pile driving is delayed
or halted due to the presence of a marine mammal, the activity may not
commence or resume until either the animal has voluntarily exited and
been visually confirmed beyond the shutdown zone (tables 18 through 20)
or 15 minutes have passed without re-detection of the animal. Further,
pile driving activity must be halted upon observation of either a
species for which incidental take is not authorized or a species for
which incidental take has been authorized but the authorized number of
takes has been met, entering or within the harassment zone. However, if
a marine mammal for which level A take has been authorized enters the
Level A harassment area and the number of authorized takes has not been
met, in-water activities would continue and PSOs would document Level A
take for the animals present within the harassment zone.
All marine mammals would be monitored in Level B harassment zones
and throughout the proposed project areas as far as visual monitoring
is reasonably possible. If a marine mammal enters a Level B harassment
zone, in-water activities would continue and PSOs would document Level
B take for the animals present within the harassment zone.
ADOT&PF must also avoid direct physical interaction with marine
mammals during construction activity. If a marine mammal comes within
10 m of such activity, operations must cease.

Table 18--Proposed Shutdown Zones and Level B Harassment Zones at Cordova
--------------------------------------------------------------------------------------------------------------------------------------------------------
Shutdown zones (meters)
Minutes per pile ------------------------------------------------------ Level B
Activity Pile size or strikes per Piles per day HF (pacific HF zones
pile LF white-sided (killer VHF PW OW (meters)
dolphin) whale)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation........ 24-inch (61 cm).. 30 minutes....... 4 piles.......... 20 10 20 20 10 5,412
30-inch (76 cm).. 60 minutes....... 2 piles.......... 40 20 30 50 20 11,659
Vibratory Removal............. 18-inch (46 cm).. 60 minutes....... 4 piles.......... 30 10 20 30 20 5,412
24-inch (61 cm).. 30 minutes....... 4 piles.......... 20 10 20 20 10
30-inch (76 cm).. 60 minutes....... 3 piles.......... 50 20 40 60 20 11,659
----------------------
Impact........................ 30-inch (76 cm).. 600 strikes...... 1 pile........... 900 110 1,585 300 300 280 1,585
2 piles.......... 900 110 1,585 300 300 280
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 23843]]

Table 19--Proposed Shutdown Zones and Level B Harassment Zones at Chenega
--------------------------------------------------------------------------------------------------------------------------------------------------------
Shutdown zones (meters)
Minutes per pile ------------------------------------------------------ Level B
Activity Pile size or strikes per Piles per day HF (pacific HF zones
pile LF white-sided (killer VHF PW OW (meters)
dolphin) whale)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation........ 24-inch (61 cm).. 15 minutes....... 4 piles.......... 10 10 10 20 10 5,412
30- and 36-inch 15 minutes....... 4 piles.......... 20 10 20 30 10 11,659
(76 and 91 cm).
Vibratory Removal............. 24-inch (61 cm).. 30 minutes....... 4 piles.......... 20 10 20 20 10 5,412
DTH (Rock Socket)............. 24-inch (61 cm).. 60 minutes....... Based on minutes 240 40 300 220 90 5,817
of DTH.
120 minutes...... 60
240 minutes...... 90
360 minutes...... 110
480 minutes...... 130
DTH (Rock Socket)............. 30- and 36-inch 60 minutes....... Based on minutes 470 80 300 300 180 15,031
(76 and 91 cm). of DTH.
120 minutes...... 120

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