Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Port of Alaska's North Extension Stabilization Step 1 (NES1) Project in Anchorage, Alaska, 76576-76623 [2023-24238]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 88, Number 213 (Monday, November 6, 2023)]
[Notices]
[Pages 76576-76623]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-24238]



[[Page 76575]]

Vol. 88

Monday,

No. 213

November 6, 2023

Part V





Department of Commerce





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National Oceanic and Atmospheric Administration





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Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to the Port of Alaska's North Extension 
Stabilization Step 1 (NES1) Project in Anchorage, Alaska; Notice

Federal Register / Vol. 88, No. 213 / Monday, November 6, 2023 / 
Notices

[[Page 76576]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD366]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the Port of Alaska's North 
Extension Stabilization Step 1 (NES1) Project in Anchorage, Alaska

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

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

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SUMMARY: NMFS has received a request from the Port of Alaska (POA) for 
authorization to take marine mammals incidental to the NES1 project at 
the existing port facility in Anchorage, Alaska. Pursuant to the Marine 
Mammal Protection Act (MMPA), NMFS is requesting comments on its 
proposal to issue an incidental harassment authorization (IHA) to 
incidentally take marine mammals during the specified activities. NMFS 
is also requesting comments on a possible one-time, 1-year renewal that 
could be issued under certain circumstances and if all requirements are 
met, as described in the Request for Public Comments section at the end 
of this notice. NMFS will consider public comments prior to making any 
final decision on the issuance of the requested MMPA authorization and 
agency responses will be summarized in the final notice of our 
decision.

DATES: Comments and information must be received no later than December 
5, 2023.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be submitted via email to 
[email protected]. Electronic copies of the application and 
supporting documents, as well as a list of the references cited in this 
document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems accessing these documents, 
please call the contact listed above.
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and will generally be posted online at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities 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: Reny Tyson Moore, 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 mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

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. 
Accordingly, NMFS has prepared an Environmental Assessment (EA) to 
consider the environmental impacts associated with the issuance of the 
proposed IHA. NMFS' EA is available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. 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 request.

Summary of Request

    On July 19, 2022, NMFS received a request from the POA for an IHA 
to take marine mammals incidental to construction activities related to 
the NES1 project in Anchorage, Alaska. Following NMFS' review of the 
application, the POA submitted revised versions on December 27, 2022, 
July 28, 2023, and August 31, 2023. The application was deemed adequate 
and complete on September 7, 2023. The POA submitted a final version 
addressing additional minor corrections on September 21, 2023. The 
POA's request is for take of seven species of marine mammals by Level B 
harassment and, for a subset of these species (i.e., harbor seal (Phoca 
vitulina) and harbor porpoise (Phocoena phocoena)), Level A harassment. 
Neither the POA nor NMFS expect serious injury or mortality to result 
from this activity and, therefore, an IHA is appropriate.
    NMFS previously issued IHAs to the POA for similar work (85 FR 
19294, April 6, 2020; 86 FR 50057, September 7, 2021). The POA complied 
with all the requirements (e.g., mitigation, monitoring, and reporting) 
of the previous IHAs, and information regarding their monitoring 
results may be found in the Effects of the Specified Activity on Marine 
Mammals and their Habitat and Estimated Take section of this notice and 
online at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.
    This proposed IHA would cover 1 year of the ongoing Port of Alaska 
Modernization Program (PAMP) for which the POA obtained prior IHAs and 
intends to request additional take authorization for subsequent facets 
of the program. The PAMP involves construction activities related to 
the

[[Page 76577]]

modernization of the POAs marine terminals.

Description of Proposed Activity

Overview

    The POA, located on Knik Arm in upper Cook Inlet, provides critical 
infrastructure for the citizens of Anchorage and a majority of the 
citizens of Alaska. The North Extension at the POA is a failed bulkhead 
structure that was constructed between 2005 and 2011. Parts of the 
North Extension bulkhead structure and the surrounding upland area are 
unstable and collapsing, and some of the sheet piles are visibly 
twisted and buckled. The structure presents safety hazards and 
logistical impediments to ongoing Port operations, and much of the 
upland area is currently unusable. The NES project would result in 
removal of the failed sheet pile structure and reconfiguration and 
realignment of the shoreline within the North Extension, including the 
conversion of approximately 0.05 square kilometers (km\2\; 13 acres) of 
developed land back to intertidal and subtidal habitat within Knik Arm. 
The NES project would be completed in two distinct steps, NES1 and 
NES2, separated by multiple years and separate permitting efforts. This 
notice is applicable to a proposed IHA for the incidental take of 
marine mammals during in-water construction associated with NES1.
    The NES1 project would involve the removal of portions of the 
failed sheet pile structure to stabilize the North Extension. The POA 
anticipates this project would begin on April 1, 2024 and extend 
through November 2024. They estimate that work would occur over 
approximately 250 hours on 110 nonconsecutive days. The NES1 project 
would remove approximately half of the North Extension structure 
extending approximately 274 meters (m) north from the southern end of 
the North Extension. This project would also stabilize the remaining 
portion of the North Extension by creating an end-state embankment. In-
water construction associated with this project includes vibratory 
installation and removal of 81 24-inch (61-centimeter (cm)) or 36-inch 
(91-cm) temporary steel pipe stability template piles and vibratory 
removal, pile splitting and pile cutting (and possible impact removal) 
of approximately 4,216 sheet piles from the structure tailwalls, cell 
faces (bulkhead), and closure walls. Sound produced by these 
construction activities may result in the take of marine mammals, by 
harassment only.

Dates and Duration

    The POA anticipates that NES1 in-water construction activities 
would begin on April 1, 2024 and extend through November 2024. In-water 
pile installation and removal associated with the NES1 project is 
anticipated to take place over approximately 246.5 hours on 110 
nonconsecutive days between these dates (see table 1 for estimated 
production rates and durations). While the exact sequence of demolition 
and construction is uncertain, an estimated schedule of sheet pile 
removal and temporary stability template pile installation and removal 
is shown in Table 2.

                                                             Table 1--Pile Installation and Removal Methods and Estimated Durations
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                                                                                                                                                        Total
                                                                                        Total      Estimated                             Maximum     duration of       Average
                                                                                      estimated    number of   Average vibratory and/     impact     removal and   production rate,   Estimated
             Pile type                      Pile size          Structural feature     number of     piles in    or splitter duration   strikes per  installation    piles per day     number of
                                                                                        piles      the water                               day        in water         (range)           days
                                                                                                                                                       (hours)
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PS 27.5 and PS 31 Sheets...........  19.69 inches (50 cm)..  Tailwalls.............        3,536        2,267  2 hours/day...........          150           157     50 (10 to 100)           46
PS 27.5 and PS 31 Sheets...........  19.69 inches (50 cm)..  Cell Faces (Bulkhead).          568          568  2 hours/day...........          150            41      30 (10 to 60)           19
PZC26 Sheets.......................  27.88 inches (70 cm)..  Closure Walls.........          110          110  2 hours/day...........          150             8     50 (10 to 100)            3
Steel Pipe.........................  24- or 36-inch (61- or  Temporary Stability              81           81  15 min/pile...........            0         20.25        4 (2 to 10)           21
                                      91-cm) install.         Templates.
Steel Pipe.........................  24- or 36-inch (61- or  Temporary Stability              81           81  15 min/pile...........            0         20.25        4 (2 to 10)           21
                                      91-cm) removal.         Templates.
                                                                                    ------------------------------------------------------------------------------------------------------------
    Total..........................  ......................  ......................  ...........  ...........  ......................  ...........         246.5  .................          110
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Note: cm = centimeter(s).


                               Table 2--Estimated Timing and Duration by Month of Pile Installation and Removal Activities
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              Activity                  April         May          June         July        August     September     October      November      Total
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36-inch (91-cm) or 24-inch (61-cm)
 stability template pile
 installation:
    Piles..........................           27           14           14           10           10            3            3            0           81
    Hours..........................         6.75         3.50         3.50          2.5          2.5         0.75         0.75            0        20.25
36-inch (91-cm) or 24-inch (61.cm)
 stability template pile removal:
    Piles..........................            0           27           13           13           13           10            4            1           81
    Hours..........................            0         6.75         3.25         3.25         3.25          2.5            1         0.25        20.25
Sheet pile vibratory hammer
 removal:
    Piles..........................  ...........  ...........  ...........  ...........  ...........  ...........  ...........  ...........  ...........
    Hours..........................           10           45           60           60           13           10            4            2          206
                                    --------------------------------------------------------------------------------------------------------------------
        Total hours................        16.75        55.25        66.75        65.75        18.75        15.25         5.75         2.25       246.50
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[[Page 76578]]

    The POA has presented this schedule using the best available 
information derived from what is known of the North Extension Site and 
the POA's experience with similar construction and demolition projects. 
The POA plans to conduct as much work as possible prior to August 
through October, when there is higher Cook Inlet beluga whale (CIBW; 
Delphinapterus leucas) abundance. However, as described below, due to 
the instability of the North Extension site, it is important that the 
POA attempt to complete the NES1 in a single construction season, which 
may necessitate work in August through October. Potential consequences 
of pausing the construction season (i.e., stopping work from August 
through October) include de-rating the structural capacity of existing 
POA docks, a shutdown of dock operations due to deteriorated 
conditions, or an actual collapse of one or more dock structures. The 
potential for collapse increases with schedule delays, due to both 
worsening deterioration and the higher probability of a significant 
seismic event.
    A typical construction season at the POA extends from approximately 
mid-April to mid-October (6 months) and may include November. Exact 
dates of ice-out in the spring and formation of new ice in the fall 
vary from year to year and cannot be predicted with accuracy. In-water 
pile installation and removal cannot occur during the winter months 
when ice is present because of the hazards associated with moving ice 
floes that change directions four times a day, preventing the use of 
tugs, barges, workboats, and other vessels. Ice movement also prevents 
accurate placement of piles.
    Due to the design of the existing sheet pile wall, demolition must 
occur in a sequential and uninterrupted manner to prevent structural 
failure of the wall as demolition progresses. This safety requirement 
limits the POA's ability to re-sequence in-water sheet pile extraction 
and temporary pile installation, as the already compromised bulkhead 
structure may become further destabilized. The POA therefore plans to 
complete all work between April and November 2024, and requests an IHA 
for the NES1 project for 1 year that is effective as of April 1, 2024. 
All pile-driving would occur during daylight hours.

Specific Geographic Region

    The Municipality of Anchorage is located in the lower reaches of 
Knik Arm of upper Cook Inlet (see Figure 2-1 in the POA's application). 
The POA sits on the industrial waterfront of Anchorage, just south of 
Cairn Point and north of Ship Creek (lat. 61[deg]15' N, long. 
149[deg]52' W; Seward Meridian). Knik Arm and Turnagain Arm are the two 
branches of upper Cook Inlet, and Anchorage is located where the two 
arms join.
    Cook Inlet is a large tidal estuary that exchanges waters at its 
mouth with the Gulf of Alaska. The inlet is roughly 20,000 km\2\ in 
area, with approximately 1,350 linear kilometer (km) of coastline (Rugh 
et al., 2000) and an average depth of approximately 100 m. Cook Inlet 
is generally divided into upper and lower regions by the East and West 
Forelands. Freshwater input to Cook Inlet comes from snowmelt and 
rivers, many of which are glacially fed and carry high sediment loads. 
Currents throughout Cook Inlet are strong and tidally periodic, with 
average velocities ranging from 3 to 6 knots (Sharma and Burrell, 
1970). Extensive tidal mudflats occur throughout Cook Inlet, especially 
in the upper reaches, and are exposed at low tides.
    Cook Inlet is a seismically active region susceptible to 
earthquakes and has some of the highest tides in North America (NOAA, 
2015) that drive surface circulation. Cook Inlet contains substantial 
quantities of mineral resources, including coal, oil, and natural gas. 
During winter, sea, beach, and river ice are dominant physical forces 
within Cook Inlet. In upper Cook Inlet, sea ice generally forms in 
October to November, and continues to develop through February or March 
(Moore et al., 2000).
    Northern Cook Inlet bifurcates into Knik Arm to the north and 
Turnagain Arm to the east. Knik Arm is generally considered to begin at 
Point Woronzof, 7.4 km southwest of the POA. From Point Woronzof, Knik 
Arm extends about 48 km in a north-northeasterly direction to the 
mouths of the Matanuska and Knik rivers. At Cairn Point, just northeast 
of the POA, Knik Arm narrows to about 2.4 km before widening to as much 
as 8 km at the tidal flats northwest of Eagle Bay at the mouth of Eagle 
River.
    Knik Arm comprises narrow channels flanked by large tidal flats 
composed of sand, mud, or gravel, depending upon location. 
Approximately 60 percent of Knik Arm is exposed at Mean Lower Low Water 
(MLLW). The intertidal (tidally influenced) areas of Knik Arm are 
mudflats, both vegetated and unvegetated, which consist primarily of 
fine, silt-sized glacial flour. Freshwater sources often are glacially 
born waters, which carry high suspended sediment loads, as well as a 
variety of metals such as zinc, barium, mercury, and cadmium. Surface 
waters in Cook Inlet typically carry high silt and sediment loads, 
particularly during summer, making Knik Arm an extremely silty, turbid 
waterbody with low visibility through the water column. The Matanuska 
and Knik Rivers contribute the majority of fresh water and suspended 
sediment into Knik Arm during summer. Smaller rivers and creeks also 
enter along the sides of Knik Arm (U.S. Department of Transportation 
and Port of Anchorage, 2008).
    Tides in Cook Inlet are semidiurnal, with two unequal high and low 
tides per tidal day (tidal day = 24 hours, 50 minutes). Due to Knik 
Arm's predominantly shallow depths and narrow widths, tides near 
Anchorage are greater than those in the main body of Cook Inlet. The 
tides at the POA have a mean range of about 8 m, and the maximum water 
level has been measured at more than 12.5 m at the Anchorage station 
(NMFS, 2015). Maximum current speeds in Knik Arm, observed during 
spring ebb tide, exceed 7 knots. These tides result in strong currents 
in alternating directions through Knik Arm and a well-mixed water 
column. The navigation harbor at the POA is a dredged basin in the 
natural tidal flat. Sediment loads in upper Cook Inlet can be high; 
spring thaws occur, and accompanying river discharges introduce 
considerable amounts of sediment into the system (Ebersole and Raad, 
2004). Natural sedimentation processes act to continuously infill the 
dredged basin each spring and summer.
    The POA's boundaries currently occupy an area of approximately 0.52 
km\2\. Other commercial and industrial activities related to secured 
maritime operations are located near the POA on Alaska Railroad 
Corporation property immediately south of the POA, on approximately 
0.45 km\2\ at a similar elevation. The POA is located north of Ship 
Creek, an area that experiences concentrated marine mammal activity 
during seasonal runs of several salmon species. Ship Creek serves as an 
important recreational fishing resource and is stocked twice each 
summer. Ship Creek flows into Knik Arm through the Municipality of 
Anchorage industrial area. Joint Base Elmendorf-Richardson (JBER) is 
located east of the POA, approximately 30.5 m higher in elevation. The 
U.S. Army Defense Fuel Support Point-Anchorage site is located east of 
the POA, south of JBER, and north of Alaska Railroad Corporation 
property. The perpendicular distance to the west bank directly across 
Knik Arm from the POA is approximately 4.2 km. The distance from the 
POA (east side)

[[Page 76579]]

to nearby Port MacKenzie (west side) is approximately 4.9 km.

Detailed Description of the Specified Activity

    The POA, located on Knik Arm in upper Cook Inlet (Figure 1), 
provides critical infrastructure for the citizens of Anchorage and a 
majority of the citizens of Alaska. Marine-side infrastructure and 
facilities at the POA were constructed largely in the 1960s and are in 
need of replacement because they are substantially past their design 
life and in poor and deteriorating structural condition. Those 
facilities include three general cargo terminals, two petroleum 
terminals, a dry barge landing, and an upland sheet-pile-supported 
storage and work area. To address deficiencies, the POA is modernizing 
its marine terminals through the PAMP to enable safe, reliable, and 
cost-effective Port operations. The PAMP will support infrastructure 
resilience in the event of a catastrophic natural disaster over a 75-
year design life.

[[Page 76580]]

[GRAPHIC] [TIFF OMITTED] TN06NO23.054

    The PAMP is critical to maintaining food and fuel security for the 
state. At the completion of the PAMP, the POA will have modern, safe, 
resilient, and efficient facilities through which more than 90 percent 
of Alaskans will continue to obtain food, supplies, tools, vehicles, 
and fuel. The PAMP is divided into five separate phases; these phases 
are designed to include projects that have independent utility yet 
streamline agency permitting. The projects associated with the PAMP 
include:
     Phase 1: Petroleum and Cement Terminal (PCT Phase 1 and 2) 
and South Floating Dock (SFD) replacement;
     Phase 2A: NES1;
     Phase 2B: General Cargo Terminals Replacement 
(construction planned to begin in 2025);
     Phase 3: Petroleum, Oil and Lubricants Terminal 2 
Replacement;
     Phase 4: NES2; and
     Phase 5: Demolition of Terminal 3.

[[Page 76581]]

    Phase 1 of the PAMP was completed in 2022. IHAs were issued by NMFS 
for both the PCT (Phase 1 and Phase 2; 85 FR 19294, April 6, 2020) and 
SFD projects associated with this Phase (86 FR 50057, September 7, 
2021). The NES Project would be completed in two distinct steps, NES1 
and NES2, separated by multiple years and separate permitting efforts. 
The project discussed herein, NES1, is Phase 2A of the PAMP. Ground 
improvements work in preparation for NES1 began in 2023, and on-shore 
and in-water work for NES1 is planned to commence in April 2024.
    The North Extension (the area north of the existing general cargo 
docks) was constructed in 2005-2011 under the Port Intermodal Expansion 
Project (PIEP), the predecessor effort to the PAMP. The POA considers 
the North Extension a failed structure. Parts of the North Extension 
bulkhead structure and the surrounding upland area are unstable and 
collapsing, and some of the sheet piles are visibly twisted and 
buckled. The structure presents safety hazards and logistical 
impediments to ongoing Port operations, and much of the upland area is 
currently unusable. The currently proposed NES Project overall would 
result in removal of the failed sheet pile structure and 
reconfiguration and realignment of the shoreline within the North 
Extension. NES1 would include the conversion of approximately 0.05 
km\2\ (13 acres) of developed land back to intertidal and subtidal 
habitat within Knik Arm. While the majority of the Project will be 
demolition work, the term ``construction'' as used herein refers to 
both construction and demolition work.
    The purpose of the NES Project is to stabilize the previously 
failed North Extension bulkhead structure and create a new shoreline 
that is structurally and seismically stable and balances the 
preservation of uplands created in the past while addressing the 
formation of unwanted sedimentation within the U.S. Army Corps of 
Engineers (USACE) Anchorage Harbor. The NES Project will also improve 
safety for maneuvering vessels at the northern berths. Previous 
establishment of the North Extension changed the hydrodynamics of the 
area and resulted in more rapid accumulation of sediments at the 
existing cargo dock faces, as well as a smaller turning area for 
vessels. The Municipality of Anchorage and the POA have identified the 
NES Project as a priority for the PAMP, due to the impact of the 
existing structure's geometry upon the USACE Anchorage Harbor Project, 
mariners' concerns regarding impacts to safe ship-berthing operations, 
and engineering concerns regarding structural and geotechnical 
stability of the system. The existing structure poses significant risk 
for continued deterioration and could result in significant release of 
impounded fill material into the Port's vessel operating and mooring 
areas, and into the USACE Anchorage Harbor Project. Accordingly, a 
significant portion of the NES work has been designated for inclusion 
in NES1 as Phase 2A PAMP efforts, specifically those portions of the 
existing structure that are closest to the north end of the existing 
cargo terminals. Creation of a safe and stable uplands area will 
support POA operations while also addressing concerns of adverse 
impacts upon the Federal Navigation Channel and Dredging Program.

Existing North Extension Structure

    The existing North Extension bulkhead structure is an OPEN CELL 
SHEET PILE (OCSP) design. Demolition of the existing OCSP structure 
will include removal and disposal of the southerly OCSP bulkhead walls 
and associated backlands. The OCSP bulkhead is a retaining structure 
filled with soil that is composed of 29 interconnected open cells, each 
approximately 8 m wide, with 30 tailwalls that are up to 61 m long (see 
Figure 1-3 in the POA's application). Each cell is about 20 sheets wide 
across the face, which is along the water. Each tailwall consists of 
approximately 118 sheet piles that extend landward into the filled 
area, orthogonal to the sheet piles along the face (table 1). The sheet 
piles interlock through a series of thumb-finger joints or interlocks 
(where two sheet piles are connected along their length; see Figure 1-5 
in the POA's application) along the cell faces and tailwalls. Wye 
joints occur where three sheet piles are connected at the interface 
between two neighboring sheet pile cell faces and the adjoining 
tailwall (see Figure 1-6 in the POA's application). Two z-pile closure 
walls close the gaps between structures, one on each end of the 
bulkhead (see Figure 1-4 in the POA's application). The total number of 
sheet piles in the existing structure that would be removed is 
approximately 4,216, although the exact number of sheet piles in the 
existing structure is not known with certainty.
    Demolition of the failed sheet pile structure would be accomplished 
through excavation and dredging of impounded soils (fill material), and 
cutting and removal of the existing sheet piles, most likely through 
use of a splitter and vibratory hammer. Demolition of the OCSP cell 
components would not commence until ground improvements necessary to 
protect the horizontal to vertical ratio (H:V) of 2H:1V embankment 
slope have been completed. Ground improvements were scheduled for 2023 
and are underway. The sequencing of in-water events, including how 
construction would proceed while maintaining stability among the 
structure's cells, is unknown. It is anticipated that the actual 
methods, including types of equipment and numbers of hours and days of 
each activity, would be determined based on the engineering 
specifications for the NES1 project as determined by the Construction 
Contractor and the Design Build Team designer of record (DOR). The NES1 
DOR and Construction Contractor have been selected by the POA, but 
their Construction Work Plan has not yet been completed and some actual 
construction techniques are likely to be refined adaptively as 
construction advances due to the stability risk of the existing 
impounded materials. The following project description is based on the 
best available information at this time considering the POA's knowledge 
of the condition of the North Extension and their experience with 
similar marine construction and demolition projects, which NMFS has 
determined sufficient for the purposes of the IHA application.

NES1 Project Activities

    The NES1 Project would result in a reconfiguration and realignment 
of the shoreline through removal of portions of the failed sheet pile 
structure to stabilize the North Extension. Before NES1 commences, the 
upland area would be prepared with ground improvements to stabilize the 
existing fill. Ground improvements will take place in the dry, landward 
of the existing failed sheet pile structure and underneath the area 
where filter rock and armor rock would later be placed to stabilize the 
new shoreline. Ground improvement work began in 2023.
    Construction of NES1 will include completion of the following 
tasks:
     Dredging and offshore disposal of approximately 1.35 
million cubic yards (CY) of material down to -12 m MLLW;
     Excavation of 115,000 CY of material;
     Demolition and removal of the failed existing sheet pile 
structure; and
     Shoreline stabilization including placement of granular 
fill, filter rock, and armor rock along the new face of the shoreline.
    NES1 would remove approximately half of the North Extension 
structure extending approximately 274 m north

[[Page 76582]]

from the southern end of the North Extension. NES1 would also stabilize 
the remaining portion of the North Extension by creating an end-state 
embankment with a top elevation of +12 m MLLW, sloping to a toe 
elevation of approximately -12 m MLLW. The lower portion of the 
embankment slope from -12 m MLLW to approximately 0 m MLLW would be 
constructed with a 6H:1V slope and would be unarmored. A grade-break 
would occur above these elevations as the slope will transition to a 
2H:1V slope armored rock revetment.
    At the cell faces, the depth of the face wall sections varies, with 
most extending from a tip elevation of approximately -60 MLLW to a 
cutoff elevation of approximately +9 m MLLW (27 m long). The mudline at 
the face sheets varies but is thought to be at approximately -11 m 
MLLW. This translates into a requirement to demolish sheet piles 
approximately 25 m high from the -14-m MLLW elevation to the top of the 
containment.
    Demolition of the failed sheet pile structure would be accomplished 
through excavation and dredging of impounded soils (fill material), and 
cutting and removal of the existing sheet piles. Approximately 
1,465,000 CY of material would be removed. The material removed from 
excavation (115,000 CY) would be stockpiled in the North Extension area 
for future use, while the dredged material (1,350,000 CY) would be 
disposed of offshore into the Anchorage Harbor Open Water Disposal 
Site, which is the authorized USACE offshore disposal area used by the 
POA under USACE permit POA-2003-00503-M20.
    The NES1 Project in-water work would begin with landside excavation 
and in-water dredging along the south shoreline and south half of the 
failed sheet pile structure. Any methodology considered for cutting and 
removing the steel sheet piles would account for worker safety, 
constructability, and minimization of potential acoustic impacts that 
the operation may have on marine mammals. The first attempt would be to 
extract the sheet piles with direct vertical pulling or with a 
vibratory hammer; however, there may be complications with the sheet 
pile interlocks, which could become seized, and other means of pile 
removal may be required (i.e. shearing or torching). Demolition 
activities would begin with the south half of the existing structure, 
followed by the north half of NES1 (see Figure 1-8 in the POA's 
application). The majority of the demolition work would occur from the 
water side to eliminate safety hazards from unexpected movements of 
fill material or the sheet piles themselves. The demolition plan also 
includes stabilization of the face sheets through installation of 
temporary piles and dredging back into the cell to relieve pressure on 
the sheet piles and to eliminate any release of material into Cook 
Inlet beyond natural tidal forces.
    Safety is a top priority regarding planning and executing the work. 
There are several risks at the project site to consider when planning 
demolition activities, such as strong currents and large tidal swings. 
Existing sheet piles and their interlocks are in poor condition. Many 
of the sheets may be damaged and bound up, making removal difficult. 
There are stability concerns with the failed OCSP structure, where the 
POA would have to closely manage allowable fill differentials between 
adjacent cells and loading on the face sheets. In-water NES1 activities 
and quantities are summarized in Table 3 (NES1 activities to be 
completed on land are summarized in table 1-2 in the POA's 
application).

    Table 3--Summary of In-Water NES1 Project Stages, Activities, and
                         Approximate Quantities
------------------------------------------------------------------------
                                                       Total anticipated
        Type of activity             Size and type     amount or number
------------------------------------------------------------------------
Dredging of fill material.......  Granular fill.....  1,350,000 CY.
At-sea transit and disposal of    Granular fill.....  1,350,000 CY.
 dredged fill.
Cutting piles with sheet          19.69-inch (50 cm)  Unknown.\1\
 splitter (vertical).              sheet piles, cut
                                   into vertical.
Cutting piles with shears or      19.69-inch (50 cm)  Unknown.\1\
 torch (horizontal) \2\.           sheet piles.
Vibratory or direct pull removal  19.69-inch (50 cm)  4,216 sheet piles.
 of sheet piles \3\.               sheet piles,
                                   removed in
                                   vertical panels.
Installation and removal of       81 24- or 36-inch   81 installations,
 temporary steel pipe piles.       (61- or 91-cm)      81 removals.
                                   piles.
Slope construction..............  Bedding, filter     60,500 CY.
                                   rock, armor stone.
------------------------------------------------------------------------
\1\ The total number of sheet piles to be cut would be a subset of the
  estimated 4,216 sheet piles needed to be removed.
\2\ Deploying divers or underwater shear equipment would be the last
  resort for removing sheet piles.
\3\ Most of the waterside face and tailwall sheets would be cut in the
  dry to improve operational safety.

Dredging and Disposal

    Dredging would be performed with a derrick barge using a clamshell 
bucket, and would likely take place for 24 hours per day for the 
duration of the project. One barge would perform the dredging 
associated with the sheet pile removal, working concurrently and in 
support of the crane barge removing the sheets. Another barge would 
perform dredging in the remaining proposed project area. This barge 
would start with removing the existing armor rock on the south slope 
and work its way north behind the OSCP bulkhead. Dredged material would 
be placed on a dump barge and taken by tug boat for disposal at the 
Anchorage Harbor Open Water Disposal Site.
    Dredging for NES1 will take place in an area that has been part of 
a working port for more than 50 years, where dredging activities are 
common. Take of marine mammals by dredging is not anticipated or 
proposed to be authorized due to the low intensity and stationary 
nature of the sounds produced by dredging and its perennial presence 
over many years in the same general location near the project site. 
Further, the sounds produced by dredging are not meaningfully different 
and are unlikely to exceed sounds produced by ongoing normal industrial 
activities at the port. Lastly, mitigation measures described in the 
Proposed Mitigation section would ensure that direct physical 
interaction with marine mammals during dredging activities would be 
avoided. Therefore, dredging will not be considered further in this 
notice.

Excavation

    Landside excavation would occur with loaders and excavators to 
remove the top portion of fill material and open up work for initial 
sheet pile cutting and removal. This excavation would begin to relieve 
pressure along the sheet wall face and expose the tops of the sheet 
piles to mitigate the risk of damaging sheets while dredging with a 
clamshell

[[Page 76583]]

bucket. The sheet piles could be more easily extracted if undamaged. 
The removal elevation would remain above +5 m MLLW in order for the 
land equipment to reach the excavation depth with the groundwater and 
tidal elevations and ensure that the removed material would be in good 
condition. The material removed would be stockpiled at the POA for 
future use. Excavation would occur out of water. Therefore, take of 
marine mammals related to excavation activities is not anticipated or 
proposed to be authorized, and it will not be considered further in 
this notice.

Pile Installation and Removal

    The sheet pile removal process would begin with the installation of 
stability templates (steel pipe piles) along the face of the sheet pile 
structure, following excavation and initial dredging work. Once 
landside excavation has removed the top portion of fill along the face 
of the wall, the POA would follow behind and begin dredging the 
material within the cells while maintaining the allowable fill 
differential between adjacent cells to maintain structural integrity. 
Before dredging deeper than the allowable elevation determined by the 
engineer, a crane barge would install temporary stability templates 
along the face of the sheet pile structure. The addition of about 27 
temporary stability templates would support about one-third of the 
bulkhead sheet pile wall during removal of the impounded material. 
These templates would reinforce the sheets as material is dredged and 
hold them upright to prohibit any sheet deformation and improve the 
efficiency and effectiveness of removal. The templates would also 
minimize the need to perform horizontal cuts at multiple elevations, 
including underwater. With strong currents and low visibility, 
performing horizontal cuts underwater poses significant challenges. 
After that area has been demolished, the temporary stability template 
piles would be removed and re-installed along the next third of the 
bulkhead. It is anticipated that three sets of 27 temporary piles would 
be required for a total of 81 installations and 81 removals (table 1). 
The POA anticipates that the temporary stability template piles would 
be 24-inch (61-cm) steel pipe piles. However, it is possible that 36-
inch (91-cm) steel pipe piles would be used instead. Temporary piles 
would be installed and removed with a vibratory hammer.
    The POA would begin on the southern end of the sheet pile structure 
and work their way north along the sheet wall face, installing 
templates and dredging fill material while managing fill elevations 
from cell to cell (see Figure 1-10 in the POA's application for an 
example section for the proposed demolition work). Fill material would 
slide down into the dredge area and would continue to be removed until 
a cell has been dredged down to -12 m MLLW adjacent to the face sheets 
and all pressure of the fill material on the face has been relieved. At 
this point in time, the crane barge would begin removing the sheet 
piles, starting with the face sheets.
    Some sheet piles from the tailwalls would be removed in the dry, 
potentially during excavation, depending on construction sequencing and 
tide heights. To minimize potential impacts on marine mammals from in-
water sheet pile removal with a vibratory hammer, removal in the dry 
would be maximized as feasible; however, until the Construction 
Contractor and DOR are under contract, the exact number of sheet piles 
that may be removed in the dry is unknown. It is estimated that 
approximately 20-30 percent of sheet piles would be removed in the dry.
    Additionally, it is possible that some sheet piles may be removed 
by direct pulling. Removal of sheet piles by direct pulling where and 
when possible would also be maximized as feasible. Once fill material 
and impounded soils have been excavated or dredged from both sides of 
the sheet piles, it may be adequate to dislodge the sheet piles out of 
interlock by lifting or direct pulling.
    Although some sheet piles and sheet pile sections would be removed 
by direct pulling and/or in the dry, it is anticipated that some sheet 
piles and sheet pile sections would need to be removed with a vibratory 
hammer in water. Sheet piles may not be extracted easily if soil 
adheres to the sheet piles along the embedded length. It is also 
possible that competent portions of the interlocks would resist 
movement, or that interlocks that are bent or damaged by shearing would 
be difficult to separate and require shaking with a vibratory hammer.
    During vibratory removal, a vibratory hammer would be suspended 
from a crane and connected to a powerpack. The extractor jaw would be 
hydraulically locked onto the web of the sheet pile. The pile would be 
vibrated as upward vertical force is applied to extract the pile. 
Ideally, the piles would slide within the interlock, separating from 
the adjacent piles. This may not always be the case, as the pile may 
bind, and multiple piles may be dislodged from the original installed 
position. Another potential outcome of a pile that binds up is that the 
pile web (the thin, flat part between the interlocks) may be 
compromised from corrosion or other damage, resulting in the web steel 
tearing and partially ripping the pile, necessitating the application 
of vertical force to a neighboring pile.
    Vertical cuts to split the sheet piles into panels may be made with 
a sheet splitter if the interlocks do not release (see Figure 1-10 in 
the POA's application). The specific tools that would be used for pile 
splitting are not known, but it is anticipated that a splitter would be 
used. A pile splitter is a stiffened steel H-beam with some of the 
webbing removed. The edges of the H-beam webbing are hardened and form 
a large wedge between the flanges. The wedge is set on top of the sheet 
pile webbing where a cut is required. The splitter is then driven with 
a hammer down the webbing of the sheet pile until the tip of the H-beam 
passes the tip of the sheets, cutting the sheet pile all the way 
through and separating it into two parts. Multiple cuts split the sheet 
pile wall into tall vertical panels that can be removed in smaller 
pieces. Cuts in the sheet piles may be spaced 4 to 6 sheets apart and 
multiple sheets or pieces would be removed together. Splitters can be 
used in the air, water, or in soils and can be driven with impact or 
vibratory hammers. The splitter would be used in conjunction with a 
vibratory hammer and the POA assumed splitting would produce the same 
or similar sound levels to a vibratory hammer used without the splitter 
attachment. Therefore, the POA combined use of a vibratory hammer to 
remove sheet piles and use of a splitter into a single category (i.e., 
vibratory hammer removal) and treated them the same for time (i.e., 
table 1) and take estimation (see the Estimated Take section).
    The POA estimates that an average of approximately 5 minutes of 
vibratory hammer application would be required to remove sheet pile 
sections. It is unknown how many sheet piles may be included in a 
section; the POA anticipates that this number will vary widely. If 
sheet piles remain seized in the sediments and cannot be loosened or 
broken free with a vibratory hammer, they may be dislodged with an 
impact hammer. Use of an impact hammer to dislodge is expected to be 
uncommon, with up to 150 strikes (an estimated 50 strikes per pile for 
up to three piles) on any individual day or approximately 5 percent of 
active hammer duration for each sheet pile. The POA would not use two 
vibratory hammers with or without splitters simultaneously.

[[Page 76584]]

    Alternative means of pile removal include dredging or excavation to 
reduce further pile embedment, and cutting sheet piles using hydraulic 
shears or underwater ultrathermic cutting. When feasible, sheet piles 
would be removed in one piece, without cutting. Similarly, use of 
cutting methods to cut piles into sections that could be more easily 
removed would take place out of water when feasible. The POA 
anticipates that hydraulic shears may be used to cut sheet piles both 
in and out of water. The POA anticipates that sounds produced by 
hydraulic shears would be brief, low level, and intermittent, imparting 
minimal sound energy into the water column. A single closure of the 
shears on sheet pile is anticipated to successfully sever one or 
multiple sheets depending on the model and jaw depth. The POA 
anticipates that a single cut may require up to 2 minutes for the 
shears to close, although the duration of a single cut is likely to be 
less than 2 minutes. Therefore, take of marine mammals associated with 
hydraulic shearing is not anticipated or proposed to be authorized.
    Underwater ultrathermic cutting is performed by commercial divers 
using hand-held equipment to cut or melt through ferrous and non-
ferrous metals, and could be used to cut the zinc-coated OCSP 
structure. These systems operate through a torch-like process, 
initiated by applying a melting amperage to a steel tube packed with 
alloy steel rods, sometimes mixed with aluminum rods to increase the 
heat output. In the hands of skilled commercial divers, underwater 
ultrathermic cutting is reputed to be relatively fast and efficient, 
cutting through approximately 2 to 4 inches (5 to 10 cm) per minute, 
depending upon the number of divers deployed. This efficacy may be 
constrained by the requirement to secure the severed piles from falling 
into the inlet to prevent an extreme hazard to the diver cutting the 
piles. Tidally driven currents in Cook Inlet may limit dive times to 
approximately 2 to 3 hours per high- and low-tide event, depending upon 
the tide cycle and the ability of divers to efficiently perform the 
cutting task while holding position during high current periods. Take 
of marine mammals associated with underwater ultrathermic cutting is 
not anticipated or proposed to be authorized as this activity is not 
considered to produce sound.
    Once the face sheets have been removed, the crane barge would 
remove the stability templates for use on other cells. At this point, 
the tailwalls would become independent walls with only fill material 
between them. The crane barge would work to extract as many tailwall 
sheets as possible until additional relief dredging is required to 
allow for vibratory removal. At this point, the crane barge would 
continue ahead to the north while the dredge rig falls back to continue 
dredging between the sheets. The POA would continue to remove the face 
wall and tailwall sheets from south to north until the OCSP structure 
has been removed.
    A key consideration of the NES1 project is to avoid rapid release 
of the impounded soils into the inlet. This is an important safety 
issue presenting a risk to construction personnel working in or near 
the cells in the immediate area of such an event. It is also an 
important operational issue to the POA, as releasing large quantities 
of materials into the inlet could quickly foul the adjoining cargo 
terminal berths (see Figure 1-7 in the POA's application). To avoid 
rapid release of the impounded soils, the demolition would need to be 
managed to account for the soil pressure of the adjacent adjoining 
cells. Failure to properly manage this process would likely result in 
the earth pressure generated by adjacent adjoining cells exerting 
lateral forces that would cause catastrophic tailwall failures. Also, 
the sheets joined in interlock are susceptible to bending in the weak 
axis, which could result in rotational forces that may overcome the 
vertical interlocks, causing the interlocks to unzip, again resulting 
in catastrophic tailwall failures and or face wall failures. Qualified 
professional engineers on the Design Build Team would develop the 
Construction Work Plan with the technical details to ameliorate these 
risks.
    The sheet pile interlocks would not prevent the flow of seawater 
into soils impounded within the OCSP cells. The water infiltration 
would be most prevalent at the face sheets; however, dynamic wave 
forces, the variable sea level height of the inlet, and variations in 
the impounded soils and associated permeability would make the 
interface elevation between unsaturated and saturated soils dynamic. 
Because saturated soils cannot resist shear, land-based excavation 
could be safely accomplished at a height above the saturated soil depth 
to be determined by the DOR, lest the equipment weight exceed the soil-
bearing capacity.

Shoreline Stabilization

    After the existing sheet pile structure has been removed, the 
sloped shoreline would be secured with armor stone placed on a layer of 
filter rock and granular fill. Placement of armor rock requires good 
visibility of the shore as each rock would be placed carefully to 
interlock with surrounding armor rock. The POA therefore anticipates 
that placement of armor rock would occur in the dry at low tide levels 
when feasible; however, some placement of armor rock, filter rock, and 
granular fill would occur in water. No impacts on marine mammals from 
placement of armor rock, filter rock, and granular fill in the dry are 
anticipated and therefore this activity will not be discussed further.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    There are seven species of marine mammals that may be found in 
upper Cook Inlet during the proposed construction and demolition 
activities. Sections 3 and 4 of the IHA application summarize available 
information regarding status and trends, distribution and habitat 
preferences, and behavior and life history of the potentially affected 
species. NMFS fully considered all of this information, and we refer 
the reader to these descriptions, instead of reprinting the 
information. Additional information regarding population trends and 
threats may be found in NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS' 
website (https://www.fisheries.noaa.gov/find-species).
    Additional information on CIBWs may be found in NMFS' 2016 Recovery 
Plan for the CIBW, available online at https://www.fisheries.noaa.gov/resource/document/recovery-plan-cook-inlet-beluga-whale-delphinapterus-leucas, and NMFS' 2023 report on the abundance and trend of CIBWs in 
Cook Inlet in June 2021 and June 2022, available online at https://www.fisheries.noaa.gov/resource/document/abundance-and-trend-belugas-delphinapterus-leucas-cook-inlet-alaska-june-2021-and.
    Table 4 lists all species or stocks for which take is expected and 
proposed to be authorized for this activity, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. PBR is defined by the MMPA as the maximum 
number of

[[Page 76585]]

animals, not including natural mortalities, that may be removed from a 
marine mammal stock while allowing that stock to reach or maintain its 
optimum sustainable population (as described in NMFS' SARs). While no 
serious injury or mortality is anticipated or proposed to be authorized 
here, PBR and annual serious injury and mortality from anthropogenic 
sources are included here as gross indicators of the status of the 
species or stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Alaska and Pacific SARs (e.g., Carretta, et al., 2023; Young 
et al., 2023). Values presented in Table 4 are the most recent 
available at the time of publication and are available online at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. The most recent abundance estimate for 
CIBWs, however, is available from Goetz et al. (2023) and available 
online at https://www.fisheries.noaa.gov/feature-story/new-abundance-estimate-endangered-cook-inlet-beluga-whales.

                                              Table 4--Species Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/MMPA status;   Stock abundance Nbest,
             Common name                  Scientific name             MMPA stock          strategic (Y/N)   (CV, Nmin, most recent     PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
    Gray whale......................  Eschrichtius robustus..  Eastern N Pacific......  -/-; N              26,960 (0.05, 25,849,         801        131
                                                                                                             2016).
Family Balaenopteridae (rorquals):
    Humpback whale..................  Megaptera novaeangliae.  Hawaii.................  -, -, N             11,278 (0.56, 7,265,          127      27.09
                                                                                                             2020).
                                                               Mexico-North Pacific...  T, D, Y             N/A (N/A, N/A, 2006)..    \6\ UND       0.57
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Order Cetartiodactyla--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Beluga whale....................  Delphinapterus leucas..  Cook Inlet.............  E/D; Y              \5\ 331 (0.076, 290,         0.53          0
                                                                                                             2022).
    Killer whale....................  Orcinus orca...........  Eastern North Pacific    -/-; N              1,920 (N/A, 1,920,             19        1.3
                                                                Alaska Resident.                             2019).
                                                               Eastern North Pacific    -/-; N              587 (N/A, 587, 2012)..        5.9        0.8
                                                                Gulf of Alaska,
                                                                Aleutian Islands and
                                                                Bering Sea Transient.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Alaska.........  -/-; Y              31,046 (0.214, N/A,       \6\ UND         72
                                                                                                             1998).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Steller sea lion................  Eumetopias jubatus.....  Western................  E/D; Y              52,932 (N/A, 52,932           318        255
                                                                                                             2019).
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina.........  Cook Inlet/Shelikof      -/-; N              28,411 (N/A, 26,907,          807        107
                                                                Strait.                                      2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
\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\ UNK means unknown.
\5\ This abundance estimate is from Goetz et al. (2023).
\6\ UND means undetermined.

    On June 15, 2023, NMFS released an updated abundance estimate for 
endangered CIBWs in Alaska (Goetz et al., 2023) that incorporates 
aerial survey data from June 2021 and 2022, but which is not included 
in the most recent SAR (Young et al., 2023). Data collected during NMFS 
recent aerial survey effort suggest that the whale population is stable 
or may be increasing slightly. Goetz et al. (2023) estimated that the 
population size is currently between 290 and 386, with a median best 
estimate of 331. In accordance with the MMPA, this population estimate 
will be incorporated into the next draft CIBW SAR, which will be 
reviewed by an independent panel of experts, the Alaska Scientific 
Review Group. After this review, the SAR will be made available as a 
draft for public review before being finalized. We have determined that 
it is appropriate to consider the CIBW estimate of abundance reported 
by Goetz et al. (2023) in our analysis rather than the older estimate 
currently available from

[[Page 76586]]

the Alaska SAR (Young et al., 2023) because it is based on the most 
recent and best available science.
    As indicated above, all seven species (with nine managed stocks) in 
Table 4 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. Minke whales 
(Balaenoptera acutorostrata) and Dall's porpoises (Phocoenoides dalli) 
also occur in Cook Inlet; however, the 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. Data from the 
Alaska Marine Mammal Stranding Network database (NMFS, unpublished 
data) provide additional support for these determinations. From 2011 to 
2020, only one minke whale and one Dall's porpoise were documented as 
stranded in the portion of Cook Inlet north of Point Possession. Both 
were dead upon discovery; it is unknown if they were alive upon their 
entry into upper Cook Inlet or drifted into the area with the tides. 
With very few exceptions, minke whales and Dall's porpoises do not 
occur in upper Cook Inlet, and therefore take of these species is 
considered unlikely.
    In addition, sea otters (Enhydra lutris) may be found in Cook 
Inlet. However, sea otters are managed by the U.S. Fish and Wildlife 
Service (USFWS) and are not considered further in this document.

Gray Whale

    The stock structure for gray whales in the Pacific has been studied 
for a number of years and remains uncertain as of the most recent 
(2022) Pacific SARs (Carretta et al., 2023). Gray whale population 
structure is not determined by simple geography and may be in flux due 
to evolving migratory dynamics (Carretta et al., 2023). Currently, the 
SARs delineate a western North Pacific (WNP) gray whale stock and an 
eastern North Pacific (ENP) stock based on genetic differentiation 
(Carretta et al., 2023). WNP gray whales are not known to feed in or 
travel to upper Cook Inlet (Conant and Lohe, 2023; Weller et al., 
2023). Therefore, we assume that gray whales near the project area are 
members of the ENP stock.
    An Unusual Mortality Event (UME) along the West Coast and in Alaska 
was declared for gray whales in January 2019 (NMFS, 2022a). Since 2019, 
143 gray whales have stranded off the coast of Alaska. Preliminary 
findings for several of the whales indicate evidence of emaciation, but 
the UME is still under investigation, and the cause of the mortalities 
remains unknown (NMFS, 2022a; see https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and for more information).
    Gray whales are infrequent visitors to Cook Inlet, but can be 
seasonally present during spring and fall in the lower inlet (Bureau of 
Ocean Energy Management (BOEM), 2021). Migrating gray whales pass 
through the lower inlet during their spring and fall migrations to and 
from their primary summer feeding areas in the Bering, Chukchi, and 
Beaufort seas (Swartz, 2018; Silber et al., 2021; BOEM, 2021).
    Gray whales are rarely documented in upper Cook Inlet and in the 
project area. Gray whales were not documented during POA construction 
or scientific monitoring from 2005 to 2011 or during 2016 (Prevel-Ramos 
et al., 2006; Markowitz and McGuire, 2007; Cornick and Saxon-Kendall, 
2008, 2009; Cornick et al., 2010, 2011; Integrated Concepts and 
Research Corporation (ICRC), 2009, 2010, 2011, 2012; Cornick and 
Pinney, 2011; Cornick and Seagars, 2016); however, one gray whale was 
observed near Port MacKenzie during 2020 PCT construction (61 North 
(61N) Environmental, 2021) and a second whale was observed off of Ship 
Creek during 2021 PCT construction monitoring (61N Environmental, 
2022a, Easley-Appleyard and Leonard, 2022). The whale observed in 2020 
is believed to be the same whale that later stranded in the Twentymile 
River, at the eastern end of Turnagain Arm, approximately 80 km 
southeast of Knik Arm. There was no indication that work at the PCT had 
any effect on the animal (see https://www.fisheries.noaa.gov/feature-story/alaska-gray-whale-ume-update-twentymile-river-whale-likely-one-twelve-dead-gray-whales for more information). No gray whales were 
observed during POA's transitional dredging or SFD construction 
monitoring from May to August, 2022 (61N Environmental, 2022b, 2022c).

Humpback Whale

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

[[Page 76587]]

this stock winter off Mexico and the Revillagigedo Archipelago and 
summer primarily in Alaska waters (Martien et al., 2021; Carretta et 
al., 2023; Young et al., 2023).
    The most comprehensive photo-identification data available suggest 
that approximately 89 percent of all humpback whales in the Gulf of 
Alaska are members of the Hawaii stock, 11 percent are from the Mexico 
stock, and less than 1 percent are from the Western North Pacific stock 
(Wade, 2021). Members of different stocks are known to intermix in 
feeding grounds.
    On October 9, 2019, NMFS proposed to designate critical habitat for 
the Western North Pacific, Mexico, and Central America DPSs of humpback 
whales (84 FR 54354). NMFS issued a final rule on April 21, 2021 to 
designate critical habitat for ESA-listed humpback whales pursuant to 
Section 4 of the ESA (86 FR 21082). There is no designated critical 
habitat for humpback whales in or near the Project area (86 FR 21082, 
April 21, 2021).
    Humpback whales are encountered regularly in lower Cook Inlet and 
occasionally in mid-Cook Inlet; however, sightings are rare in upper 
Cook Inlet (e.g., Witteveen et al., 2011). During aerial surveys 
conducted in summers between 2005 and 2012, Shelden et al. (2013) 
reported dozens of sightings in lower Cook Inlet, a handful of 
sightings in the vicinity of Anchor Point and in lower Cook Inlet, and 
no sightings north of 60[deg] N latitude. NMFS changed to a biennial 
survey schedule starting in 2014 after analysis showed there would be 
little reduction in the ability to detect a trend given the current 
growth rate of the population (Hobbs, 2013). No survey took place in 
2020. Instead, consecutive surveys took place in 2021 and 2022 (Shelden 
et al., 2022). During the 2014-2022 aerial surveys, sightings of 
humpback whales were recorded in lower Cook Inlet and mid-Cook Inlet, 
but none were observed in upper Cook Inlet (Shelden et al., 2015b, 
2017, 2019, 2022). Vessel-based observers participating in the Apache 
Corporation's 2014 survey operations recorded three humpback whale 
sightings near Moose Point in upper Cook Inlet and two sightings near 
Anchor Point, while aerial and land-based observers recorded no 
humpback whale sightings, including in the upper inlet (Lomac-MacNair 
et al., 2014). Observers monitoring waters between Point Campbell and 
Fire Island during summer and fall 2011 and spring and summer 2012 
recorded no humpback whale sightings (Brueggeman et al., 2013). 
Monitoring of Turnagain Arm during ice-free months between 2006 and 
2014 yielded one humpback whale sighting (McGuire, unpublished data, 
cited in LGL Alaska Research Associates, Inc., and DOWL, 2015).
    There have been few sightings of humpback whales in the vicinity of 
the proposed project area. Humpback whales were not documented during 
POA construction or scientific monitoring from 2005 to 2011, in 2016, 
or during 2020 (Prevel-Ramos et al., 2006; Markowitz and McGuire, 2007; 
Cornick and Saxon-Kendall, 2008, 2009; Cornick et al., 2010, 2011; 
ICRC, 2009, 2010, 2011, 2012; Cornick and Pinney, 2011; Cornick and 
Seagars, 2016; 61N Environmental, 2021). Observers monitoring the Ship 
Creek Small Boat Launch from August 23 to September 11, 2017 recorded 
two sightings, each of a single humpback whale, which was presumed to 
be the same individual (POA, 2017). One other humpback whale sighting 
has been recorded for the immediate vicinity of the project area. This 
event involved a stranded whale that was sighted near a number of 
locations in upper Cook Inlet before washing ashore at Kincaid Park in 
2017; it is unclear as to whether the humpback whale was alive or 
deceased upon entering Cook Inlet waters. Another juvenile humpback 
stranded in Turnagain Arm in April 2019 near mile 86 of the Seward 
Highway. One additional humpback whale was observed in July during 2022 
transitional dredging monitoring (61N Environmental, 2022c). No 
humpback whales were observed during the 2020 to 2021 PCT construction 
monitoring, the NMFS marine mammal monitoring, or the 2022 SFD 
construction monitoring from April to June (61N Environmental, 2021, 
2022a, 2022b, 2022c; Easley-Appleyard and Leonard, 2022).

Beluga Whale

    Five stocks of beluga whales are recognized in Alaska: the Beaufort 
Sea stock, eastern Chukchi Sea stock, eastern Bering Sea stock, Bristol 
Bay stock, and Cook Inlet stock (Young et al., 2023). The Cook Inlet 
stock is geographically and genetically isolated from the other stocks 
(O'Corry-Crowe et al., 1997; Laidre et al., 2000) and resides year-
round in Cook Inlet (Laidre et al., 2000; Castellote et al., 2020). 
Only the Cook Inlet stock (CIBWs) inhabits the proposed project area. 
CIBWs were designated as a DPS and listed as endangered under the ESA 
in October 2008 (73 FR 62919, October 10, 2008).
    Shelden and Wade (2019) analyzed time-series CIBW abundance data 
from 2008 to 2018 and reported that the CIBW population was declining 
at an annual rate of 2.3 percent during this time. Goetz et al., (2023) 
suggest that this decline could have been part of a natural oscillation 
in the population or possibly due to impacts of the unprecedented 
heatwave in the Gulf of Alaska during the same time period. The CIBW 
time-series abundance data were analyzed using a Bayesian statistical 
method to estimate group size for calculating CIBW abundance. This 
method produced an abundance estimate of 279 CIBWs, with a 95 percent 
probability range of 250 to 317 whales (Shelden and Wade, 2019).
    In June 2023, NMFS released an updated abundance estimate for CIBWs 
in Alaska that incorporates aerial survey data from June 2021 and 2022 
and accounted for visibility bias (i.e., availability bias due to 
diving behavior; proximity bias due to individuals concealed by another 
individual in the video data; perception bias due to individuals not 
detected because of small image size in the video data; and individual 
observer bias in visual observer data) (Goetz et al., 2023). This 
report estimated that CIBW abundance is between 290 and 386, with a 
median best estimate of 331. Goetz et al. (2023) also present an 
analysis of population trends for the most recent 10-year period (2012-
2022). The addition of data from the 2021 and 2022 survey years in the 
analysis resulted in a 65.1 percent probability that the CIBW 
population is now increasing at 0.9 percent per year (95 percent 
prediction interval of -3 to 5.7 percent). This increase drops slightly 
to 0.2 percent per year (95 percent prediction interval of -1.8 to 2.6 
percent) with a 60 percent probability that the CIBW population is 
increasing more than 1 percent per year when data from 2021, which had 
limited survey coverage due to poor weather, are excluded from the 
analysis. Median group size estimates in 2021 and 2022 were 34 and 15, 
respectively (Goetz et al., 2023). For management purposes, NMFS has 
determined that the carrying capacity of Cook Inlet is 1,300 CIBWs (65 
FR 34590, May 31, 2000) based on historical CIBW abundance estimated by 
Calkins (1989).
    Live stranding events of CIBWs have been regularly observed in 
upper Cook Inlet. This can occur when an individual or group of 
individuals strands as the tide recedes. Most live strandings have 
occurred in Knik Arm and Turnagain Arm, which are shallow and have 
large tidal ranges, strong currents, and extensive mudflats. Most 
whales involved in a live stranding event survive, although some 
associated deaths may not be observed if the whales die later from 
live-stranding-

[[Page 76588]]

related injuries (Vos and Shelden, 2005; Burek-Huntington et al., 
2015). Between 2014 and 2018, there were reports of approximately 79 
CIBWs involved in three known live stranding events, plus one suspected 
live stranding event with two associated deaths reported (NMFS, 2016b; 
NMFS, unpublished data; Muto et al., 2020). In 2014, necropsy results 
from two whales found in Turnagain Arm suggested that a live stranding 
event contributed to their deaths as both had aspirated mud and water. 
No live stranding events were reported prior to the discovery of these 
dead whales, suggesting that not all live stranding events are 
observed.
    Another source of CIBW mortality in Cook Inlet is predation by 
transient-type (mammal-eating) killer whales (NMFS, 2016b; Shelden et 
al., 2003). No human-caused mortality or serious injury of CIBWs 
through interactions with commercial, recreational, and subsistence 
fisheries, takes by subsistence hunters, and or human-caused events 
(e.g., entanglement in marine debris, ship strikes) has been recently 
documented and harvesting of CIBWs has not occurred since 2008 (NMFS, 
2008b).
    Recovery Plan. In 2010, a Recovery Team, consisting of a Science 
Panel and Stakeholder Panel, began meeting to develop a Recovery Plan 
for the CIBW. The Final Recovery Plan was published in the Federal 
Register on January 5, 2017 (82 FR 1325). In September 2022, NMFS 
completed the ESA 5-year review for the CIBW DPS and determined that 
the CIBW DPS should remain listed as endangered (NMFS, 2022d).
    In its Recovery Plan (82 FR 1325, January 5, 2017), NMFS identified 
several potential threats to CIBWs, including: (1) high concern: 
catastrophic events (e.g., natural disasters, spills, mass strandings), 
cumulative effects of multiple stressors, and noise; (2) medium 
concern: disease agents (e.g., pathogens, parasites, and harmful algal 
blooms), habitat loss or degradation, reduction in prey, and 
unauthorized take; and (3) low concern: pollution, predation, and 
subsistence harvest. The recovery plan did not treat climate change as 
a distinct threat but rather as a consideration in the threats of high 
and medium concern. Other potential threats most likely to result in 
direct human-caused mortality or serious injury of this stock include 
vessel strikes.
    Critical Habitat. On April 11, 2011, NMFS designated two areas of 
critical habitat for CIBW (76 FR 20179). The designation includes 7,800 
km\2\ of marine and estuarine habitat within Cook Inlet, encompassing 
approximately 1,909 km\2\ in Area 1 and 5,891 km\2\ in Area 2 (see 
Figure 1 in 76 FR 20179). Area 1 of the CIBW critical habitat 
encompasses all marine waters of Cook Inlet north of a line connecting 
Point Possession (lat. 61.04[deg] N, long. 150.37[deg] W) and the mouth 
of Three Mile Creek (lat. 61.08.55[deg] N, long. 151.04.40[deg] W), 
including waters of the Susitna, Little Susitna, and Chickaloon Rivers 
below mean higher high water. From spring through fall, Area 1 critical 
habitat has the highest concentration of CIBWs due to its important 
foraging and calving habitat. Area 2 critical habitat has a lower 
concentration of CIBWs in spring and summer but is used by CIBWs in 
fall and winter. Critical habitat does not include two areas of 
military usage: the Eagle River Flats Range on Fort Richardson and 
military lands of JBER between Mean Higher High Water and MHW. 
Additionally, the POA, adjacent navigation channel, and turning basin 
were excluded from critical habitat designation due to national 
security reasons (76 FR 20180, April 11, 2011). The POA exclusion area 
is within Area 1, however, marine mammal monitoring results from the 
POA suggest that this exclusion area is not a particularly important 
feeding or calving area. CIBWs have been occasionally documented to 
forage around Ship Creek (south of the POA) but are typically 
transiting through the area to other, potentially richer, foraging 
areas to the north (e.g., Six Mile Creek, Eagle River, Eklutna River) 
(e.g., 61N Environmental, 2021, 2022a, 2022b, 2022c, Easley-Appleyard 
and Leonard, 2022). These locations contain predictable salmon runs, an 
important food source for CIBWs, and the timing of these runs has been 
correlated with CIBW movements into the upper reaches of Knik Arm (Ezer 
et al., 2013). More information on CIBW critical habitat can be found 
at https://www.fisheries.noaa.gov/action/critical-habitat-cook-inlet-beluga-whale.
    The designation identified the following Primary Constituent 
Elements, essential features important to the conservation of the CIBW:
    (1) Intertidal and subtidal waters of Cook Inlet with depths of 
less than 9 m (MLLW) and within 8 km of high- and medium-flow 
anadromous fish streams;
    (2) Primary prey species, including four of the five species of 
Pacific salmon (chum (Oncorhynchus keta), sockeye (Oncorhynchus nerka), 
Chinook (Oncorhynchus tshawytscha), and coho (Oncorhynchus kisutch)), 
Pacific eulachon (Thaleichthys pacificus), Pacific cod (Gadus 
macrocephalus), walleye Pollock (Gadus chalcogrammus), saffron cod 
(Eleginus gracilis), and yellowfin sole (Limanda aspera);
    (3) The absence of toxins or other agents of a type or amount 
harmful to CIBWs;
    (4) Unrestricted passage within or between the critical habitat 
areas; and
    (5) The absence of in-water noise at levels resulting in the 
abandonment of habitat by CIBWs.
    Biologically Important Areas. Wild et al. (2023) delineated 
portions of Cook Inlet, including near the proposed project area, as a 
Biologically Important Area (BIA) for the small and resident population 
of CIBWs based on scoring methods outlined by Harrison et al. (2023) 
(see https://oceannoise.noaa.gov/biologically-important-areas for more 
information). The BIA is used year-round by CIBWs for feeding and 
breeding, and there are limits on food supply such as salmon runs and 
seasonal movement of other fish species (Wild et al., 2023). The 
boundary of the CIBW BIA is consistent with NMFS' critical habitat 
designation, and does not include the aforementioned exclusion areas 
(e.g., the POA and surrounding waters) (Wild et al., 2023).
    Foraging Ecology. CIBWs feed on a wide variety of prey species, 
particularly those that are seasonally abundant. From late spring 
through summer, most CIBW stomachs sampled contained salmon, which 
corresponded to the timing of fish runs in the area. Anadromous smolt 
and adult fish aggregate at river mouths and adjacent intertidal 
mudflats (Calkins, 1989). All five Pacific salmon species (i.e., 
Chinook, pink (Oncorhynchus gorbuscha), coho, sockeye, and chum) spawn 
in rivers throughout Cook Inlet (Moulton, 1997; Moore et al., 2000). 
Overall, Pacific salmon represent the highest percent frequency of 
occurrence of prey species in CIBW stomachs. This suggests that their 
spring feeding in upper Cook Inlet, principally on fat-rich fish such 
as salmon and eulachon, is important to the energetics of these animals 
(NMFS, 2016b).
    The nutritional quality of Chinook salmon in particular is 
unparalleled, with an energy content four times greater than that of a 
Coho salmon. It is suggested the decline of the Chinook salmon 
population has left a nutritional void in the diet of the CIBWs that no 
other prey species can fill in terms of quality or quantity (Norman et 
al., 2020, 2022).
    In fall, as anadromous fish runs begin to decline, CIBWs return to 
consume fish species (cod and bottom fish) found in nearshore bays and 
estuaries. Stomach samples from CIBWs are not available for winter 
(December through

[[Page 76589]]

March), although dive data from CIBWs tagged with satellite 
transmitters suggest that they feed in deeper waters during winter 
(Hobbs et al., 2005), possibly on such prey species as flatfish, cod, 
sculpin, and pollock.
    Distribution in Cook Inlet. The CIBW stock remains within Cook 
Inlet throughout the year, showing only small seasonal shifts in 
distribution (Goetz et al., 2012a; Lammers et al., 2013; Castallotte et 
al., 2015; Shelden et al., 2015a, 2018; Lowery et al., 2019). During 
spring and summer, CIBWs generally aggregate near the warmer waters of 
river mouths where prey availability is high and predator occurrence is 
low (Moore et al., 2000; Shelden and Wade, 2019; McGuire et al., 2020). 
In particular, CIBW groups are seen in the Susitna River Delta, the 
Beluga River and along the shore to the Little Susitna River, Knik Arm, 
and along the shores of Chickaloon Bay. Small groups were recorded 
farther south in Kachemak Bay, Redoubt Bay (Big River), and Trading Bay 
(McArthur River) prior to 1996, but rarely thereafter. Since the mid-
1990s, most CIBWs (96 to 100 percent) aggregate in shallow areas near 
river mouths in upper Cook Inlet, and they are only occasionally 
sighted in the central or southern portions of Cook Inlet during summer 
(Hobbs et al., 2008). Almost the entire population can be found in 
northern Cook Inlet from late spring through the summer and into the 
fall (Muto et al., 2020).
    Data from tagged whales (14 tags deployed July 2000 through March 
2003) show that CIBWs use upper Cook Inlet intensively between summer 
and late autumn (Hobbs et al., 2005). CIBWs tagged with satellite 
transmitters continue to use Knik Arm, Turnagain Arm, and Chickaloon 
Bay as late as October, but some range into lower Cook Inlet to 
Chinitna Bay, Tuxedni Bay, and Trading Bay (McArthur River) in fall 
(Hobbs et al., 2005, 2012). From September through November, CIBWs move 
between Knik Arm, Turnagain Arm, and Chickaloon Bay (Hobbs et al., 
2005; Goetz et al., 2012b). By December, CIBWs are distributed 
throughout the upper to mid-inlet. From January into March, they move 
as far south as Kalgin Island and slightly beyond in central offshore 
waters. CIBWs make occasional excursions into Knik Arm and Turnagain 
Arm in February and March in spite of ice cover (Hobbs et al., 2005). 
Although tagged CIBWs move widely around Cook Inlet throughout the 
year, there is no indication of seasonal migration in and out of Cook 
Inlet (Hobbs et al., 2005). Data from NMFS aerial surveys, 
opportunistic sighting reports, and corrected satellite-tagged CIBWs 
confirm that they are more widely dispersed throughout Cook Inlet 
during winter (November-April), with animals found between Kalgin 
Island and Point Possession. Generally fewer observations of CIBWs are 
reported from the Anchorage and Knik Arm area from November through 
April (76 FR 20179, April 11, 2011; Rugh et al., 2000, 2004).
    The NMFS Marine Mammal Lab has conducted long-term passive acoustic 
monitoring demonstrating seasonal shifts in CIBW concentrations 
throughout Cook Inlet. Castellote et al. (2015) conducted long-term 
acoustic monitoring at 13 locations throughout Cook Inlet between 2008 
and 2015: North Eagle Bay, Eagle River Mouth, South Eagle Bay, Six 
Mile, Point MacKenzie, Cairn Point, Fire Island, Little Susitna, Beluga 
River, Trading Bay, Kenai River, Tuxedni Bay, and Homer Spit; the 
former six stations being located within Knik Arm. In general, the 
observed seasonal distribution is in accordance with descriptions based 
on aerial surveys and satellite telemetry: CIBW detections are higher 
in the upper inlet during summer, peaking at Little Susitna, Beluga 
River, and Eagle Bay, followed by fewer detections at those locations 
during winter. Higher detections in winter at Trading Bay, Kenai River, 
and Tuxedni Bay suggest a broader CIBW distribution in the lower inlet 
during winter.
    Goetz et al. (2012b) modeled habitat preferences using NMFS' 1994-
2008 June abundance survey data. In large areas, such as the Susitna 
Delta (Beluga to Little Susitna Rivers) and Knik Arm, there was a high 
probability that CIBWs were in larger groups. CIBW presence and 
acoustic foraging behavior also increased closer to rivers with Chinook 
salmon runs, such as the Susitna River (e.g., Castellote et al., 2021). 
Movement has been correlated with the peak discharge of seven major 
rivers emptying into Cook Inlet. Boat-based surveys from 2005 to the 
present (McGuire and Stephens, 2017) and results from passive acoustic 
monitoring across the entire inlet (Castellote et al., 2015) also 
support seasonal patterns observed with other methods. Based on long-
term passive acoustic monitoring, seasonally, foraging behavior was 
more prevalent during summer, particularly at upper inlet rivers, than 
during winter. Foraging index was highest at Little Susitna, with a 
peak in July[hyphen]August and a secondary peak in May, followed by 
Beluga River and then Eagle Bay; monthly variation in the foraging 
index indicates CIBWs shift their foraging behavior among these three 
locations from April through September.
    CIBWs are believed to mostly calve in the summer, and concurrently 
breed between late spring and early summer (NMFS, 2016b), primarily in 
upper Cook Inlet. The only known observed occurrence of calving 
occurred on July 20, 2015, in the Susitna Delta area (T. McGuire, 
personal communication, March 27, 2017). The first neonates encountered 
during each field season from 2005 through 2015 were always seen in the 
Susitna River Delta in July. The photographic identification team's 
documentation of the dates of the first neonate of each year indicate 
that calving begins in mid-late July/early August, generally coinciding 
with the observed timing of annual maximum group size. Probable mating 
behavior of CIBWs was observed in April and May of 2014, in Trading 
Bay. Young CIBWs are nursed for 2 years and may continue to associate 
with their mothers for a considerable time thereafter (Colbeck et al., 
2013). Important calving grounds are thought to be located near the 
river mouths of upper Cook Inlet.
    Presence in Project Area. Knik Arm is one of three areas in upper 
Cook Inlet where CIBWs are concentrated during spring, summer, and 
early fall. Most CIBWs observed in or near the POA are transiting 
between upper Knik Arm and other portions of Cook Inlet, and the POA 
itself is not considered high-quality foraging habitat. CIBWs tend to 
follow their anadromous prey and travel in and out of Knik Arm with the 
tides. The predictive habitat model derived by Goetz et al. (2012a) 
indicated that CIBW density ranges from 0 to 1.12 whales per km\2\ in 
Cook Inlet. The highest predicted densities of CIBWs are in Knik Arm, 
near the mouth of the Susitna River, and in Chickaloon Bay. The model 
suggests that the density of CIBWs at the mouth of Knik Arm, near the 
POA, ranges between approximately 0.013 and 0.062 whales per km\2\. The 
distribution presented by Goetz et al. (2012a) is generally consistent 
with CIBW distribution documented in upper Cook Inlet throughout ice-
free months (NMFS, 2016b).
    Several marine mammal monitoring programs and studies have been 
conducted at or near the POA during the last 17 years. These studies 
offer some of the best available information on the presence of CIBWs 
in the proposed project area. Studies that occurred prior to 2020 are 
summarized in Section 4.5.5 of the POA's application. More recent 
programs, which most accurately portray current information regarding 
CIBW presence in the proposed project area, are summarized here.

[[Page 76590]]

    PCT Construction Monitoring (2020-2021). A marine mammal monitoring 
program was implemented during construction of the PCT in 2020 (Phase 
1) and 2021 (Phase 2), as required by the NMFS IHAs (85 FR 19294, April 
6, 2020). PCT Phase 1 construction included impact installation of 48-
inch (122-cm) attenuated piles; impact installation of 36-inch (91-cm) 
and 48-inch (122-cm) unattenuated piles; vibratory installation of 24-
inch (61-cm), 36-inch (91-cm), and 48-inch (122 cm) attenuated and 
unattenuated piles; and vibratory installation of an unattenuated 72-
inch (183-cm) bubble curtain across 95 days. PCT Phase 2 construction 
included vibratory installation of 36-inch (91-cm) attenuated piles and 
impact and vibratory installation of 144-inch (366-cm) attenuated 
breasting and mooring dolphins across 38 days. Marine mammal monitoring 
in 2020 occurred during 128 non-consecutive days, with a total of 
1,238.7 hours of monitoring from April 27 to November 24, 2020 (61N 
Environmental, 2021). Marine mammal monitoring in 2021 occurred during 
74 non-consecutive days, with a total of 734.9 hours of monitoring from 
April 26 to June 24 and September 7 to 29, 2021 (61N Environmental, 
2022a). A total of 1,504 individual CIBWs across 377 groups were 
sighted during PCT construction monitoring. Sixty-five and sixty-seven 
percent of CIBW observations occurred on non-pile driving days or 
before pile driving occurred on a given day during PCT Phase 1 and PCT 
Phase 2 construction, respectively.
    The monitoring effort and data collection were conducted before, 
during, and after pile driving activities from four locations as 
stipulated by the PCT IHAs (85 FR 19294, April 6, 2020): (1) the 
Anchorage Public Boat Dock by Ship Creek, (2) the Anchorage Downtown 
Viewpoint near Point Woronzof, (3) the PCT construction site, and (4) 
the North End (North Extension) at the north end of the POA, near Cairn 
Point. Marine mammal sighting data from April to September both before, 
during, and after pile driving indicate that CIBWs swam near the POA 
and lingered there for periods of time ranging from a few minutes to a 
few hours. CIBWs were most often seen traveling at a slow or moderate 
pace, either from the north near Cairn Point or from the south or 
milling at the mouth of Ship Creek. Groups of CIBWs were also observed 
swimming north and south in front of the PCT construction, and did not 
appear to exhibit avoidance behaviors either before, during, or after 
pile driving activities (61N Environmental, 2021, 2022a). CIBW 
sightings in June were concentrated on the west side of Knik Arm from 
the Little Susitna River Delta to Port MacKenzie. From July through 
September, CIBWs were most often seen milling and traveling on the east 
side of Knik Arm from Point Woronzof to Cairn Point (61N Environmental, 
2021, 2022a).
    SFD Construction Monitoring and Transitional Dredging (2022). In 
2022, a marine mammal monitoring program almost identical to that used 
during PCT construction was implemented during construction of the SFD, 
as required by the NMFS IHA (86 FR 50057, September 7, 2021). SFD 
construction included the vibratory installation of ten 36-inch (91-cm) 
attenuated plumb piles and two unattenuated battered piles (61N 
Environmental, 2022b). Marine mammal monitoring was conducted during 13 
non-consecutive days, with a total of 108.2 hours of monitoring 
observation from May 20 through June 11, 2022 (61N Environmental, 
2022b). Forty-one individual CIBWs across 9 groups were sighted (61N 
Environmental, 2022b). One group was observed on a day with no pile-
driving, three groups were seen on days before pile driving activities 
started, and five groups were seen during vibratory pile driving 
activities (61N Environmental, 2022b).
    During SFD construction, the position of the Ship Creek monitoring 
station was adjusted to allow monitoring of a portion of the shoreline 
north of Cairn Point that could not be seen by the station at the 
northern end of the POA (61N Environmental, 2022b). Eleven protected 
species observers (PSOs) worked from four monitoring stations located 
along a 9-km (6-mi) stretch of coastline surrounding the POA. The 
monitoring effort and data collection were conducted at the following 
four locations: (1) Point Woronzof approximately 6.5 km (4 mi) 
southwest of the SFD, (2) the promontory near the boat launch at Ship 
Creek, (3) the SFD project site, and (4) the northern end of the POA 
(61N Environmental, 2022b).
    Ninety groups comprised of 529 CIBWs were also sighted during the 
transitional dredging monitoring that occurred from May 3 to 15, 2022 
and June 27 to August 24, 2022 (61N Environmental, 2022b). Of the nine 
groups of CIBWs sighted during SFD construction, traveling was recorded 
as the primary behavior for each group (61N Environmental, 2022b). 
CIBWs traveled and milled between the SFD construction area, Ship 
Creek, and areas to the south of the POA for more than an hour at a 
time, delaying some construction activities.

Killer Whale

    Along the west coast of North America, seasonal and year-round 
occurrence of killer whales has been noted along the entire Alaska 
coast (Braham and Dahlheim, 1982), in British Columbia and Washington 
inland waterways (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). Killer whales from these areas have been 
labeled as ``resident,'' ``transient,'' and ``offshore'' type killer 
whales (Bigg et al., 1990; Ford et al., 2000; Dahlheim et al., 2008) 
based on aspects of morphology, ecology, genetics, and behavior (Ford 
and Fisher, 1982; Baird and Stacey, 1988; Baird et al., 1992; Hoelzel 
et al., 1998, 2002; Barrett Lennard, 2000; Dahlheim et al., 2008). 
Based on data regarding association patterns, acoustics, movements, and 
genetic differences, eight killer whale stocks are now recognized 
within the U.S. Pacific, two of which have the potential to be found in 
the proposed project area: the Eastern North Pacific Alaska Resident 
stock and the Gulf of Alaska, Aleutian Islands, and the Bering Sea 
Transient stock. Both stocks overlap the same geographic area; however, 
they maintain social and reproductive isolation and feed on different 
prey species. Resident killer whales are primarily fish-eaters, while 
transients primarily hunt and consume marine mammals, such as harbor 
seals, Dall's porpoises, harbor porpoises, beluga whales and sea lions. 
Killer whales are not harvested for subsistence in Alaska. Potential 
threats most likely to result in direct human-caused mortality or 
serious injury of killer whales in this region include oil spills, 
vessel strikes, and interactions with fisheries.
    Killer whales are rare in Cook Inlet, and most individuals are 
observed in lower Cook Inlet (Shelden et al., 2013). The infrequent 
sightings of killer whales that are reported in upper Cook Inlet tend 
to occur when their primary prey (anadromous fish for resident killer 
whales and beluga whales for transient killer whales) are also in the 
area (Shelden et al., 2003). During CIBW aerial surveys between 1993 
and 2012, killer whales were sighted in lower Cook Inlet 17 times, with 
a total of 70 animals (Shelden et al., 2013); no killer whales were 
observed in upper Cook Inlet during this time. Surveys over 20 years by 
Shelden et al. (2003) documented an increase in CIBW sightings and 
strandings in upper Cook Inlet beginning in the early 1990s. Several of 
these sightings and strandings reported evidence of killer whale

[[Page 76591]]

predation on CIBWs. The pod sizes of killer whales preying on CIBWs 
ranged from one to six individuals (Shelden et al., 2003). Passive 
acoustic monitoring efforts throughout Cook Inlet documented killer 
whales at the Beluga River, Kenai River, and Homer Spit, although they 
were not encountered within Knik Arm (Castellote et al., 2016). These 
detections were likely resident killer whales. Transient killer whales 
likely have not been acoustically detected due to their propensity to 
move quietly through waters to track prey (Small, 2010; Lammers et al., 
2013).
    Few killer whales, if any, are expected to approach or be in the 
vicinity of the proposed project area. No killer whales were spotted in 
the vicinity of the POA during surveys by Funk et al. (2005), Ireland 
et al. (2005), or Brueggeman et al. (2007, 2008a, 2008b). Killer whales 
have also not been documented during any POA construction or scientific 
monitoring from 2005 to 2011, in 2016, or in 2020 (Prevel-Ramos et al., 
2006; Markowitz and McGuire, 2007; Cornick and Saxon-Kendall, 2008; 
ICRC, 2009, 2010, 2011, 2012; Cornick et al., 2010, 2011; Cornick and 
Pinney, 2011; Cornick and Seagars, 2016; 61N Environmental, 2021). Two 
killer whales, one male and one juvenile of unknown sex, were sighted 
offshore of Point Woronzof in September 2021 during PCT Phase 2 
construction monitoring (61N Environmental, 2022a). The pair of killer 
whales moved up Knik Arm, reversed direction near Cairn Point, and 
moved southwest out of Knik Arm toward the open water of Upper Cook 
Inlet. No killer whales were sighted during the 2021 NMFS marine mammal 
monitoring or the 2022 transitional dredging and SFD construction 
monitoring that occurred between May and June 2022 (61N Environmental, 
2022b, 2022c; Easley-Appleyard and Leonard, 2022).

Harbor Porpoise

    In the eastern North Pacific Ocean, harbor porpoise range from 
Point Barrow, along the Alaska coast, and down the west coast of North 
America to Point Conception, California. The 2022 Alaska SARs describe 
a revised stock structure for harbor porpoises (Young et al., 2023). 
Previously, NMFS had designated three stocks of harbor porpoises: the 
Bering Sea stock, the Gulf of Alaska stock, and the Southeast Alaska 
stock (Muto et al., 2022; Zerbini et al., 2022). The 2022 Alaska SARs 
splits the Southeast Alaska stock into three separate stocks, resulting 
in five separate stocks in Alaskan waters for this species. This update 
better aligns harbor porpoise stock structure with genetics, trends in 
abundance, and information regarding discontinuous distribution trends 
(Young et al., 2023). Harbor porpoises found in Cook Inlet are assumed 
to be members of the Gulf of Alaska stock (Young et al., 2023).
    Harbor porpoises occur most frequently in waters less than 100 m 
deep (Hobbs and Waite, 2010). They can be opportunistic foragers but 
consume primarily schooling forage fish (Bowen and Siniff, 1999). Given 
their shallow water distribution, harbor porpoise are vulnerable to 
physical modifications of nearshore habitats resulting from urban and 
industrial development (including waste management and nonpoint source 
runoff) and activities such as construction of docks and other over-
water structures, filling of shallow areas, dredging, and noise 
(Linnenschmidt et al., 2013). Subsistence users have not reported any 
harvest from the Gulf of Alaska harbor porpoise stock since the early 
1900s (Shelden et al., 2014). Calving occurs from May to August; 
however, this can vary by region. Harbor porpoises are often found 
traveling alone, or in small groups of less than 10 individuals 
(Schmale, 2008).
    Harbor porpoises occur throughout Cook Inlet, with passive acoustic 
detections being more prevalent in lower Cook Inlet. Although harbor 
porpoises have been frequently observed during aerial surveys in Cook 
Inlet (Shelden et al., 2014), most sightings are of single animals and 
are concentrated at Chinitna and Tuxedni bays on the west side of lower 
Cook Inlet (Rugh et al., 2005). The occurrence of larger numbers of 
porpoise in the lower Cook Inlet may be driven by greater availability 
of preferred prey and possibly less competition with CIBWs, as CIBWs 
move into upper inlet waters to forage on Pacific salmon during the 
summer months (Shelden et al., 2014).
    An increase in harbor porpoise sightings in upper Cook Inlet was 
observed over recent decades (e.g., 61N Environmental, 2021, 2022a; 
Shelden et al., 2014). Small numbers of harbor porpoises have been 
consistently reported in upper Cook Inlet between April and October 
(Prevel-Ramos et al., 2008). The overall increase in the number of 
harbor porpoise sightings in upper Cook Inlet is unknown, although it 
may be an artifact from increased studies and marine mammal monitoring 
programs in upper Cook Inlet. It is also possible that the contraction 
in the CIBW's range has opened up previously occupied CIBW range to 
harbor porpoises (Shelden et al., 2014).
    Harbor porpoises have been observed within Knik Arm during 
monitoring efforts from 2005 to 2016. Between April 27 and November 24, 
2020, 18 harbor porpoises were observed near the POA during the PCT 
Phase 1 construction monitoring (61N Environmental, 2021). Twenty-seven 
harbor porpoises were observed near the POA during the PCT Phase 2 
construction monitoring conducted between April 26 and September 29, 
2021 (61N Environmental, 2022a). During NMFS marine mammal monitoring 
conducted in 2021, one harbor porpoise was observed in August and six 
harbor porpoises were observed in October (Easley-Appleyard and 
Leonard, 2022). During 2022, five harbor porpoises were sighted during 
transitional dredging monitoring (61N Environmental, 2022c). No harbor 
porpoises were sighted at the POA during the 2022 SFD construction 
monitoring that occurred between May and June 2022 (61N Environmental, 
2022b).

Steller Sea Lion

    Two Distinct Population Segments (DPSs) of Steller sea lion occur 
in Alaska: the western DPS and the eastern DPS. The western DPS 
includes animals that occur west of Cape Suckling, Alaska, and 
therefore includes individuals within the Project area. The western DPS 
was listed under the ESA as threatened in 1990 (55 FR 49204, November 
26, 1990), and its continued population decline resulted in a change in 
listing status to endangered in 1997 (62 FR 24345, May 5, 1997). Since 
2000, studies indicate that the population east of Samalga Pass (i.e., 
east of the Aleutian Islands) has increased and is potentially stable 
(Young et al., 2023).
    There is uncertainty regarding threats currently impeding the 
recovery of Steller sea lions, particularly in the Aleutian Islands. 
Many factors have been suggested as causes of the steep decline in 
abundance of western Steller sea lions observed in the 1980s, including 
competitive effects of fishing, environmental change, disease, 
contaminants, killer whale predation, incidental take, and illegal and 
legal shooting (Atkinson et al., 2008; NMFS, 2008a). A number of 
management actions have been implemented since 1990 to promote the 
recovery of the Western U.S. stock of Steller sea lions, including 5.6-
km (3-nautical mile) no-entry zones around rookeries, prohibition of 
shooting at or near sea lions, and regulation of fisheries for sea lion 
prey species (e.g., walleye pollock, Pacific cod, and Atka mackerel 
(Pleurogrammus monopterygius)) (Sinclair et al., 2013; Tollit et al., 
2017). Additionally, potentially deleterious events, such as harmful 
algal blooms

[[Page 76592]]

(Lefebvre et al., 2016) and disease transmission across the Arctic 
(VanWormer et al., 2019) that have been associated with warming waters, 
could lead to potentially negative population-level impacts on Steller 
sea lions.
    NMFS designated critical habitat for Steller sea lions on August 
27, 1993 (58 FR 45269). The critical habitat designation for the 
Western DPS of was determined to include a 37-km (20-nautical mile) 
buffer around all major haul-outs and rookeries, and associated 
terrestrial, atmospheric, and aquatic zones, plus three large offshore 
foraging areas, none of which occurs in the project area.
    Steller sea lions are opportunistic predators, feeding primarily on 
a wide variety of seasonally abundant fishes and cephalopods, including 
Pacific herring (Clupea pallasi), walleye pollock, capelin (Mallotus 
villosus), Pacific sand lance (Ammodytes hexapterus), Pacific cod, 
salmon (Oncorhynchus spp.), and squid (Teuthida spp.); (Jefferson et 
al., 2008; Wynne et al., 2011). Steller sea lions do not generally eat 
every day, but tend to forage every 1-2 days and return to haulouts to 
rest between foraging trips (Merrick and Loughlin, 1997; Rehberg et 
al., 2009). Steller sea lions feed largely on walleye pollock, salmon, 
and arrowtooth flounder during the summer, and walleye pollock and 
Pacific cod during the winter (Sinclair and Zeppelin, 2002). Except for 
salmon, none of these are found in abundance in upper Cook Inlet 
(Nemeth et al., 2007).
    Within Cook Inlet, Steller sea lions primarily inhabit lower Cook 
Inlet. However, they occasionally venture to upper Cook Inlet and Knik 
Arm and may be attracted to salmon runs in the region. Steller sea 
lions have not been documented in upper Cook Inlet during CIBW aerial 
surveys conducted annually in June from 1994 through 2012 and in 2014 
(Shelden et al., 2013, 2015b, 2017; Shelden and Wade, 2019); however, 
there has been an increase in individual Steller sea lion sightings 
near the POA in recent years.
    Steller sea lions were observed near the POA in 2009, 2016, and 
2019 through 2022 (ICRC, 2009; Cornick and Seagars, 2016; POA, 2019; 
61N Environmental, 2021, 2022a, 2022b, 2022c). In 2009, there were 
three Steller sea lion sightings that were believed to be the same 
individual (ICRC, 2009). In 2016, Steller sea lions were observed on 2 
separate days. On May 2, 2016, one individual was sighted, while on May 
25, 2016, there were five Steller Sea lion sightings within a 50-minute 
period, and these sightings occurred in areas relatively close to one 
another (Cornick and Seagars, 2016). Given the proximity in time and 
space, it is believed these five sightings were of the same individual 
sea lion. In 2019, one Steller sea lion was observed in June at the POA 
during transitional dredging (POA, 2019). There were six sightings of 
individual Steller sea lions near the POA during PCT Phase 1 
construction monitoring (61N Environmental, 2021). At least two of 
these sightings may have been re-sights on the same individual. An 
additional seven unidentified pinnipeds were observed that could have 
been Steller sea lions or harbor seals (61N Environmental, 2021). In 
2021, there were a total of eight sightings of individual Steller sea 
lions observed near the POA during PCT Phase 2 construction monitoring 
(61N Environmental, 2022a). During NMFS marine mammal monitoring, one 
Steller sea lion was observed in August 2021 in the middle of the inlet 
(Easley-Appleyard and Leonard, 2022). In 2022, there were three Steller 
sea lion sightings during the transitional dredging monitoring and 
three during SFD construction monitoring (61N Environmental, 2022b, 
2022c). All sightings occurred during summer, when the sea lions were 
likely attracted to ongoing salmon runs. Sea lion observations near the 
POA may be increasing due to more consistent observation effort or due 
to increased presence; observations continue to be occasional.

Harbor Seal

    Harbor seals inhabit waters all along the western coast of the 
United States, British Columbia, and north through Alaska waters to the 
Pribilof Islands and Cape Newenham. NMFS currently identifies 12 stocks 
of harbor seals in Alaska based largely on genetic structure (Young et 
al., 2023). Harbor seals in the proposed project area are members of 
the Cook Inlet/Shelikof stock, which ranges from the southwest tip of 
Unimak Island east along the southern coast of the Alaska Peninsula to 
Elizabeth Island off the southwest tip of the Kenai Peninsula, 
including Cook Inlet, Knik Arm, and Turnagain Arm. Distribution of the 
Cook Inlet/Shelikof stock extends from Unimak Island, in the Aleutian 
Islands archipelago, north through all of upper and lower Cook Inlet 
(Young et al., 2023).
    Harbor seals forage in marine, estuarine, and occasionally 
freshwater habitat. They are opportunistic feeders that adjust their 
local distribution to take advantage of locally and seasonally abundant 
prey (Baird, 2001; Bj[oslash]rge, 2002). In Cook Inlet, harbor seals 
have been documented in higher concentrations near steelhead 
(Oncorhynchus mykiss), Chinook, and salmon spawning streams during 
summer and may target more offshore prey species during winter (Boveng 
et al., 2012).
    Harbor seals haul out on rocks, reefs, beaches, and drifting 
glacial ice (Young et al., 2023). Their movements are influenced by 
tides, weather, season, food availability, and reproduction, as well as 
individual sex and age class (Lowry et al., 2001; Small et al., 2003; 
Boveng et al., 2012). The results of past and recent satellite tagging 
studies in Southeast Alaska, Prince William Sound, Kodiak Island, and 
Cook Inlet are also consistent with the conclusion that harbor seals 
are non-migratory (Lowry et al., 2001; Small et al., 2003; Boveng et 
al., 2012). However, some long-distance movements of tagged animals in 
Alaska have been recorded (Pitcher and McAllister, 1981; Lowry et al., 
2001; Small et al., 2003; Womble, 2012; Womble and Gende, 2013). Strong 
fidelity of individuals for haul-out sites during the breeding season 
has been documented in several populations (H[auml]rk[ouml]nen and 
Harding, 2001), including some regions in Alaska such as Kodiak Island, 
Prince William Sound, Glacier Bay/Icy Strait, and Cook Inlet (Pitcher 
and McAllister, 1981; Small et al., 2005; Boveng et al., 2012; Womble, 
2012; Womble and Gende, 2013). Harbor seals usually give birth to a 
single pup between May and mid-July; birthing locations are dispersed 
over several haulout sites and not confined to major rookeries 
(Klinkhart et al., 2008).
    Harbor seals inhabit the coastal and estuarine waters of Cook Inlet 
and are observed in both upper and lower Cook Inlet throughout most of 
the year (Boveng et al., 2012; Shelden et al., 2013). Recent research 
on satellite-tagged harbor seals observed several movement patterns 
within Cook Inlet (Boveng et al., 2012), including a strong seasonal 
pattern of more coastal and restricted spatial use during the spring 
and summer (breeding, pupping, molting) and more wide-ranging movements 
within and outside of Cook Inlet during the winter months, with some 
seals ranging as far as Shumagin Islands. During summer months, 
movements and distribution were mostly confined to the west side of 
Cook Inlet and Kachemak Bay, and seals captured in lower Cook Inlet 
generally exhibited site fidelity by remaining south of the Forelands 
in lower Cook Inlet after release (Boveng et al., 2012). In the fall, a 
portion of the harbor seals appeared to move out of Cook Inlet and into 
Shelikof Strait, northern Kodiak Island, and coastal habitats of the

[[Page 76593]]

Alaska Peninsula. The western coast of Cook Inlet had higher usage by 
harbor seals than eastern coast habitats, and seals captured in lower 
Cook Inlet generally exhibited site fidelity by remaining south of the 
Forelands in lower Cook Inlet after release (south of Nikiski; Boveng 
et al., 2012).
    The presence of harbor seals in upper Cook Inlet is seasonal. 
Harbor seals are commonly observed along the Susitna River and other 
tributaries within upper Cook Inlet during eulachon and salmon 
migrations (NMFS, 2003). The major haulout sites for harbor seals are 
in lower Cook Inlet; however, there are a few haulout sites in upper 
Cook Inlet, including near the Little and Big Susitna rivers, Beluga 
River, Theodore River, and Ivan River (Barbara Mahoney, personal 
communication, November 16, 2020; Montgomery et al., 2007). During CIBW 
aerial surveys of upper Cook Inlet from 1993 to 2012, harbor seals were 
observed 24 to 96 km south-southwest of Anchorage at the Chickaloon, 
Little Susitna, Susitna, Ivan, McArthur, and Beluga rivers (Shelden et 
al., 2013). Harbor seals have been observed in Knik Arm and in the 
vicinity of the POA (Shelden et al., 2013), but they are not known to 
haul out within the proposed project area.
    Harbor seals were observed during construction monitoring at the 
POA from 2005 through 2011 and in 2016 (Prevel-Ramos et al., 2006; 
Markowitz and McGuire, 2007; Cornick and Saxon-Kendall, 2008, 2009; 
Cornick et al., 2010, 2011). Harbor seals were observed in groups of 
one to seven individuals (Cornick et al., 2011; Cornick and Seagars, 
2016). Harbor seals were also observed near the POA during construction 
monitoring for PCT Phase 1 in 2020 and PCT Phase 2 in 2021, NMFS marine 
mammal monitoring in 2021, and transitional dredging monitoring and SFD 
construction monitoring in 2022 (61N Environmental, 2021, 2022a, 2022b, 
2022c, Easley-Appleyard and Leonard, 2022). During the 2020 PCT Phase 1 
and 2021 PCT Phase 2 construction monitoring, harbor seals were 
regularly observed in the vicinity of the POA with frequent 
observations near the mouth of Ship Creek, located approximately 2,500 
m southeast of the NES1 location. Harbor seals were observed almost 
daily during 2020 PCT Phase 1 construction, with 54 individuals 
documented in July, 66 documented in August, and 44 sighted in 
September (61N Environmental, 2021). During the 2021 PCT Phase 2 
construction, harbor seals were observed with the highest numbers of 
sightings in June (87 individuals) and in September (124 individuals) 
(61 N Environmental, 2022a). Over the 13 days of SFD construction 
monitoring in May and June 2022, 27 harbor seals were observed (61N 
Environmental, 2022b). Seventy-two groups of 75 total harbor seals (3 
groups of 2 individuals) were observed during transitional dredging 
monitoring in 2022 (61N Environmental, 2022c). Sighting rates of harbor 
seals have been highly variable and may have increased since 2005. It 
is unknown whether any potential increase was due to local population 
increases or habituation to ongoing construction activities. It is 
possible that increased sighting rates are correlated with more 
intensive monitoring efforts in 2020 and 2021, when the POA used 11 
PSOs spread among four monitoring stations.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65-
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 5. 
Specific to this action, gray whales and humpback whales are considered 
low-frequency (LF) cetaceans, beluga whales and killer whales are 
considered mid-frequency (MF) cetaceans, harbor porpoises are 
considered high-frequency (HF) cetaceans, Steller sea lions are otariid 
pinnipeds, and harbor seals are phocid pinnipeds.

                  Table 5--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans           150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true    275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)     50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65-dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al., 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013). This division between phocid and otariid pinnipeds is now 
reflected in the updated hearing groups proposed in Southall et al. 
(2019).
    For more detail concerning these groups and associated frequency 
ranges,

[[Page 76594]]

please see NMFS (2018) 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 section, and the Proposed Mitigation section, to draw 
conclusions regarding the likely impacts of these activities on the 
reproductive success or survivorship of individuals and whether those 
impacts are reasonably expected to, or reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.
    Acoustic effects on marine mammals during the specified activity 
are expected to potentially occur from vibratory pile installation and 
removal, and impact pile removal. The effects of underwater noise from 
the POA's proposed activities have the potential to result in Level B 
harassment of marine mammals in the action area and, for some species 
as a result of certain activities, Level A harassment.

Background on Sound

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used relevant to 
the specified activity and to a discussion of the potential effects of 
the specified activity on marine mammals found later in this document. 
For general information on sound and its interaction with the marine 
environment, please see: Erbe and Thomas (2022); Au and Hastings 
(2008); Richardson et al. (1995); Urick (1983); as well as the 
Discovery of Sound in the Sea website at https://dosits.org/.
    Sound is a vibration that travels as an acoustic wave through a 
medium such as a gas, liquid or solid. Sound waves alternately compress 
and decompress the medium as the wave travels. In water, sound waves 
radiate in a manner similar to ripples on the surface of a pond and may 
be either directed in a beam (narrow beam or directional sources) or 
sound may radiate in all directions (omnidirectional sources), as is 
the case for sound produced by the construction activities considered 
here. The compressions and decompressions associated with sound waves 
are detected as changes in pressure by marine mammals and human-made 
sound receptors such as hydrophones.
    Sound travels more efficiently in water than almost any other form 
of energy, making the use of sound as a primary sensory modality ideal 
for inhabitants of the aquatic environment. In seawater, sound travels 
at roughly 1,500 meters per second (m/s). In air, sound waves travel 
much more slowly at about 340 m/s. However, the speed of sound in water 
can vary by a small amount based on characteristics of the transmission 
medium such as temperature and salinity.
    The basic characteristics of a sound wave are frequency, 
wavelength, velocity, and amplitude. Frequency is the number of 
pressure waves that pass by a reference point per unit of time and is 
measured in hertz (Hz) or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly with 
distance, except in certain cases in shallower water. The amplitude of 
a sound pressure wave is related to the subjective ``loudness'' of a 
sound and is typically expressed in decibels (dB), which are a relative 
unit of measurement that is used to express the ratio of one value of a 
power or pressure to another. A sound pressure level (SPL) in dB is 
described as the ratio between a measured pressure and a reference 
pressure, and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. For example, a 10-dB increase is a 
ten-fold increase in acoustic power. A 20-dB increase is then a 100-
fold increase in power and a 30-dB increase is a 1000-fold increase in 
power. However, a ten-fold increase in acoustic power does not mean 
that the sound is perceived as being 10 times louder. The dB is a 
relative unit comparing two pressures; therefore, a reference pressure 
must always be indicated. For underwater sound, this is 1 microPascal 
([mu]Pa). For in-air sound, the reference pressure is 20 microPascal 
([mu]Pa). The amplitude of a sound can be presented in various ways; 
however, NMFS typically considers three metrics: sound exposure level 
(SEL), root-mean-square (RMS) SPL, and peak SPL (defined below). The 
source level represents the SPL referenced at a standard distance from 
the source, typically 1 m (Richardson et al., 1995; American National 
Standards Institute (ANSI, 2013), while the received level is the SPL 
at the receiver's position. For pile driving activities, the SPL is 
typically referenced at 10 m.
    SEL (represented as dB referenced to 1 micropascal squared second 
(re 1 [mu]Pa\2\-s)) represents the total energy in a stated frequency 
band over a stated time interval or event, and considers both intensity 
and duration of exposure. The per-pulse SEL (e.g., single strike or 
single shot SEL) is calculated over the time window containing the 
entire pulse (i.e., 100 percent of the acoustic energy). SEL can also 
be a cumulative metric; it can be accumulated over a single pulse (for 
pile driving this is the same as single-strike SEL, above; 
SELss), or calculated over periods containing multiple 
pulses (SELcum). Cumulative SEL (SELcum) 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. The SEL metric is useful because it 
allows sound exposures of different durations to be related to one 
another in terms of total acoustic energy. The duration of a sound 
event and the number of pulses, however, should be specified as there 
is no accepted standard duration over which the summation of energy is 
measured.
    RMS SPL is equal to 10 times the logarithm (base 10) of the ratio 
of the mean-square sound pressure to the specified reference value, and 
given in units of dB (International Organization for Standardization 
(ISO), 2017). RMS is calculated by squaring all of the sound 
amplitudes, averaging the squares, and then taking the square root of 
the average (Urick, 1983). RMS accounts for both positive and negative 
values; squaring the pressures makes all values positive so that they 
may be accounted for in the summation of pressure levels (Hastings and 
Popper, 2005). This measurement is often used in the context of 
discussing behavioral effects, in part because behavioral effects, 
which often result from auditory cues, may be better expressed through 
averaged units than by peak SPL. For impulsive sounds, RMS is 
calculated by the portion of the waveform containing 90 percent of the 
sound energy from the impulsive event (Madsen, 2005).
    Peak SPL (also referred to as zero-to-peak sound pressure or 0-pk) 
is the maximum instantaneous sound pressure measurable in the water, 
which can arise from a positive or negative sound pressure, during a 
specified time, for a specific frequency range at a specified distance 
from the source, and is represented in the same units as the RMS sound 
pressure (ISO, 2017). Along with SEL, this metric is used in evaluating 
the potential for permanent

[[Page 76595]]

threshold shift (PTS) and temporary threshold shift (TTS) associated 
with impulsive sound sources.
    Sounds are also characterized by their temporal components. 
Continuous sounds are those whose sound pressure level remains above 
that of the ambient or background sound with negligibly small 
fluctuations in level (ANSI, 2005) while intermittent sounds are 
defined as sounds with interrupted levels of low or no sound (National 
Institute for Occupational Safety and Health (NIOSH), 1998). A key 
distinction between continuous and intermittent sound sources is that 
intermittent sounds have a more regular (predictable) pattern of bursts 
of sounds and silent periods (i.e., duty cycle), which continuous 
sounds do not.
    Sounds may be either impulsive or non-impulsive (defined below). 
The distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to noise-induced hearing loss (e.g., Ward, 1997 in Southall et 
al., 2007). Please see NMFS (2018) and Southall et al. (2007, 2019) for 
an in-depth discussion of these concepts.
    Impulsive sound sources (e.g., explosions, gunshots, sonic booms, 
seismic airgun shots, impact pile driving) produce signals that are 
brief (typically considered to be less than 1 second), broadband, 
atonal transients (ANSI, 1986, 2005; NIOSH, 1998) and occur either as 
isolated events or repeated in some succession. Impulsive sounds are 
all characterized by a relatively rapid rise from ambient pressure to a 
maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features. Impulsive 
sounds are intermittent in nature. The duration of such sounds, as 
received at a distance, can be greatly extended in a highly reverberant 
environment.
    Non-impulsive sounds can be tonal, narrowband, or broadband, brief 
or prolonged, and may be either continuous or non-continuous (ANSI, 
1995; NIOSH, 1998). Some of these non-impulsive sounds can be transient 
signals of short duration but without the essential properties of 
impulses (e.g., rapid rise time). Examples of non-impulsive sounds 
include those produced by vessels, aircraft, machinery operations such 
as drilling or dredging, vibratory pile driving, and active sonar 
systems.
    Even in the absence of sound from the specified activity, the 
underwater environment is characterized by sounds from both natural and 
anthropogenic sound sources. Ambient sound is defined as a composite of 
naturally-occurring (i.e., non-anthropogenic) sound from many sources 
both near and far (ANSI, 1995). Background sound is similar, but 
includes all sounds, including anthropogenic sounds, minus the sound 
produced by the proposed activities (NMFS, 2012, 2016a). The sound 
level of a region is defined by the total acoustical energy being 
generated by known and unknown sources. These sources may include 
physical (e.g., wind and waves, earthquakes, ice, atmospheric sound), 
biological (e.g., sounds produced by marine mammals, fish, and 
invertebrates), and anthropogenic (e.g., vessels, dredging, 
construction) sound. A number of sources contribute to background and 
ambient sound, including wind and waves, which are a main source of 
naturally occurring ambient sound for frequencies between 200 Hz and 50 
kilohertz (kHz) (Mitson, 1995). In general, background and ambient 
sound levels tend to increase with increasing wind speed and wave 
height. Precipitation can become an important component of total sound 
at frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times. Marine mammals can contribute significantly to background and 
ambient sound levels, as can some fish and snapping shrimp. The 
frequency band for biological contributions is from approximately 12 Hz 
to over 100 kHz. Sources of background sound related to human activity 
include transportation (surface vessels), dredging and construction, 
oil and gas drilling and production, geophysical surveys, sonar, and 
explosions. Vessel noise typically dominates the total background sound 
for frequencies between 20 and 300 Hz. In general, the frequencies of 
many anthropogenic sounds, particularly those produced by construction 
activities, are below 1 kHz (Richardson et al., 1995). When sounds at 
frequencies greater than 1 kHz are produced, they generally attenuate 
relatively rapidly (Richardson et al., 1995), particularly above 20 kHz 
due to propagation losses and absorption (Urick, 1983).
    Transmission loss (TL) defines the degree to which underwater sound 
has spread in space and lost energy after having moved through the 
environment and reached a receiver. It is defined by the ISO as the 
reduction in a specified level between two specified points that are 
within an underwater acoustic field (ISO, 2017). Careful consideration 
of transmission loss and appropriate propagation modeling is a crucial 
step in determining the impacts of underwater sound, as it helps to 
define the ranges (isopleths) to which impacts are expected and depends 
significantly on local environmental parameters such as seabed type, 
water depth (bathymetry), and the local speed of sound. Geometric 
spreading laws are powerful tools which provide a simple means of 
estimating TL, based on the shape of the sound wave front in the water 
column. For a sound source that is equally loud in all directions and 
in deep water, the sound field takes the form of a sphere, as the sound 
extends in every direction uniformly. In this case, the intensity of 
the sound is spread across the surface of the sphere, and thus we can 
relate intensity loss to the square of the range (as area = 4*pi*r\2\). 
When expressing logarithmically in dB as TL, we find that TL = 
20*Log10(range), this situation is known as spherical 
spreading. In shallow water, the sea surface and seafloor will bound 
the shape of the sound, leading to a more cylindrical shape, as the top 
and bottom of the sphere is truncated by the largely reflective 
boundaries. This situation is termed cylindrical spreading, and is 
given by TL = 10*Log10(range) (Urick, 1983). An intermediate 
scenario may be defined by the equation TL = 
15*Log10(range), and is referred to as practical spreading. 
Though these geometric spreading laws do not capture many often 
important details (scattering, absorption, etc.), they offer a 
reasonable and simple approximation of how sound decreases in intensity 
as it is transmitted. In the absence of measured data indicating the 
level of transmission loss at a given site for a specific activity, 
NMFS recommends practical spreading (i.e., 15*Log10(range)) 
to model acoustic propagation for construction activities in most 
nearshore environments.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time depends not only on the source levels, but 
also on the propagation of sound through the environment. 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, background and 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

[[Page 76596]]

can vary by 10 to 20 dB from day to day (Richardson et al., 1995). The 
result is that, depending on the source type and its intensity, sound 
from the specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    Background underwater noise levels in the NES1 Project area are 
both variable and relatively high, primarily because of extreme tidal 
activity, elevated sediment loads in the water column, periodic high 
winds, the seasonal presence of ice, and anthropogenic activities. 
Sources of anthropogenic noise in the NES1 Project area consist of 
dredging operations, boats, ships, oil and gas operations, construction 
noise, and aircraft overflights from JBER and Ted Stevens International 
Airport, all of which contribute to high underwater noise levels in 
upper Cook Inlet (e.g., Blackwell and Greene, 2002; (Knik Arm Bridge 
and Toll Authority (KABATA), 2011). The lower range of broadband (10 to 
10,000 Hz) background sound levels obtained during underwater 
measurements at Port MacKenzie, located across Knik Arm from the POA, 
ranged from 115 to 133 dB re 1 [mu]Pa RMS (Blackwell, 2005). Background 
sound levels measured during the 2007 test pile study for the POA's 
Marine Terminal Redevelopment Project (MTRP) site ranged from 105 to 
135 dB (URS Corporation, 2007). The background SPLs obtained in that 
study were highly variable, with most SPL recordings exceeding 120 dB 
RMS. Background sound levels measured in 2008 at the MTRP site ranged 
from 120 to 150 dB RMS (Scientific Fishery Systems, Inc., 2009). These 
measurements included industrial sounds from maritime operations, but 
ongoing USACE maintenance dredging and pile driving from construction 
were not underway at the time of the study.
    Background sound levels were measured at the POA during the PAMP 
2016 Test Pile Program (TPP) in the absence of pile driving at two 
locations during a 3[hyphen]day break in pile installation. Median 
background noise levels, measured at a location just offshore of the 
POA SFD and at a second location about 1 km offshore, were 117 and 
122.2 dB RMS, respectively (Austin et al., 2016). NMFS considers the 
median sound levels to be most appropriate when considering background 
noise levels for purposes of evaluating the potential impacts of the 
proposed project on marine mammals (NMFS, 2012). By using the median 
value, which is the 50th percentile of the measurements, for background 
noise levels, one will be able to eliminate the few transient loud 
identifiable events that do not represent the true ambient condition of 
the area. This is relevant because during 2 of the 4 days (50 percent) 
when background measurement data were being collected, the USACE was 
dredging Terminal 3 (located just north of the Ambient-Offshore 
hydrophone) for 24 hours per day with two 1-hour breaks for crew 
change. On the last 2 days of data collection, no dredging was 
occurring. Therefore, the median provides a better representation of 
background noise levels when the NES1 project would be occurring. 
During the measurements, some typical sound signals were noted, such as 
noise from current flow and the passage of vessels.
    With regard to spatial considerations of the measurements, the 
offshore location is most applicable to assessing background sound 
during the NES1 Project (NMFS, 2012). The median background noise level 
measured at the offshore hydrophone was 122.2 dB RMS. The measurement 
location closer to the POA was quieter, with a median of 117 dB; 
however, that hydrophone was placed very close to a dock. During PCT 
acoustic monitoring, noise levels in Knik Arm absent pile driving were 
also collected (Illingworth & Rodkin (I&R), 2021a, 2022b)); however, 
the PCT IHAs did not require background noise measurements to be 
collected. These measurements were not collected in accordance to NMFS 
(2012) guidance for measuring background noise and thus cannot be used 
here for that purpose. Despite this, the noise levels measured during 
the PCT project were not significantly different from 122.2 dB (I&R, 
2021a, 2022b). If additional background data are collected in the 
future in this region, NMFS may re-evaluate the data to appropriately 
characterize background sound levels in Knik Arm.

Description of Sound Sources for the Specified Activities

    In-water construction activities associated with the project that 
have the potential to incidentally take marine mammals through exposure 
to sound would include impact sheet pile removal, vibratory pile 
installation and removal, and pile splitting (assumed to be similar to 
vibratory pile installation and removal). Impact hammers typically 
operate by repeatedly dropping and/or pushing a heavy piston onto a 
pile to drive the pile into the substrate. For the NES1 project, a 
small number of strikes from an impact hammer may be used to loosen 
sheet piles for removal. Sound generated by impact hammers is 
impulsive, 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 
typically produce less sound (i.e., lower levels) than impact hammers. 
Peak 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; California Department of Transportation 
(CALTRANS), 2015, 2020). Sounds produced by vibratory hammers are non-
impulsive; the rise time is slower, reducing the probability and 
severity of injury, and the sound energy is distributed over a greater 
amount of time (Nedwell and Edwards, 2002; Carlson et al., 2005).
    The likely or possible impacts of the POA's proposed activities 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, given there are no 
known pinniped haul-out sites in the vicinity of the NES1 project site, 
visual and other non-acoustic stressors would be limited, and any 
impacts to marine mammals are expected to primarily be acoustic in 
nature.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving is the primary means by which marine 
mammals may be harassed from the POA's specified activity. 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 pile driving 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). Exposure to anthropogenic noise 
can also lead to non-observable physiological responses, such as an 
increase in stress hormones. Additional noise in a marine mammal's 
habitat can mask acoustic cues used by marine mammals to carry out 
daily functions, such as communication and predator and prey detection. 
The effects of pile driving noise on marine mammals are dependent on 
several factors, including, but not limited to, sound type (e.g., 
impulsive vs. non-impulsive), the species, age and sex class (e.g., 
adult male vs. mom with calf), duration of

[[Page 76597]]

exposure, the distance between the pile and the animal, received 
levels, behavior at time of exposure, and previous history with 
exposure (Wartzok et al., 2004; Southall et al., 2007). Here we discuss 
physical auditory effects (threshold shifts) followed by behavioral 
effects and potential impacts on habitat.
    NMFS defines a noise-induced threshold shift (TS) as a change, 
usually an increase, in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS (2018) there are numerous factors to 
consider when examining the consequence of TS, including, but not 
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough 
duration or to a high enough level to induce a TS, the magnitude of the 
TS, time to recovery (seconds to minutes or hours to days), the 
frequency range of the exposure (i.e., spectral content), the hearing 
frequency range of the exposed species relative to the signal's 
frequency spectrum (i.e., how animal uses sound within the frequency 
band of the signal; e.g., Kastelein et al., 2014), and the overlap 
between the animal and the source (e.g., spatial, temporal, and 
spectral).
    Permanent Threshold Shift (PTS). NMFS defines PTS as a permanent, 
irreversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). 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). A temporary, reversible increase 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018). Based on data from marine mammal TTS measurements 
(see Southall et al., 2007, 2019), a TTS of 6 dB is considered the 
minimum threshold shift clearly larger than any day-to-day or session-
to-session variation in a subject's normal hearing ability (Finneran et 
al., 2000, 2002; Schlundt et al., 2000). As described in Finneran 
(2015), marine mammal studies have shown the amount of TTS increases 
with 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 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 
cetaceans, published data on the onset of TTS are limited to captive 
bottlenose dolphin (Tursiops truncatus), beluga whale, harbor porpoise, 
and Yangtze finless porpoise (Neophocoena asiaeorientalis) (Southall et 
al., 2019). 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). TTS was not 
observed in spotted (Phoca largha) and ringed (Pusa hispida) seals 
exposed to single airgun impulse sounds at levels matching previous 
predictions of TTS onset (Reichmuth et al., 2016). These studies 
examine 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 threshold shift 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 and harbor porpoises have a lower TTS onset than other measured 
pinniped or cetacean 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, cumulative 
SEL will overestimate the amount of TTS from intermittent exposures, 
such as sonars and impulsive sources. Nachtigall et al. (2018) describe 
measurements of hearing sensitivity of multiple odontocete species 
(bottlenose dolphin, harbor porpoise, beluga, and false killer whale 
(Pseudorca crassidens)) when a relatively loud sound was preceded by

[[Page 76598]]

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). Data available on noise-induced 
hearing loss for mysticetes are currently lacking (NMFS, 2018). 
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, and there is no PTS data for cetaceans, 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 decibels above that inducing mild TTS (e.g., a 40-dB threshold 
shift approximates PTS onset (Kryter et al., 1966; Miller, 1974), while 
a 6-dB threshold shift 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 cumulative sound exposure level thresholds are 15 to 20 dB higher 
than TTS cumulative sound exposure level 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.
    Behavioral Harassment. Exposure to noise also has the potential to 
behaviorally disturb marine mammals to a level that rises to the 
definition of harassment under the MMPA. Generally speaking, NMFS 
considers a behavioral disturbance that rises to the level of 
harassment under the MMPA a non-minor response--in other words, not 
every response qualifies as behavioral disturbance, and for responses 
that do, those of a higher level, or accrued across a longer duration, 
have the potential to affect foraging, reproduction, or survival. 
Behavioral disturbance may include a variety of effects, including 
subtle changes in behavior (e.g., minor or brief avoidance of an area 
or changes in vocalizations), more conspicuous changes in similar 
behavioral activities, and more sustained and/or potentially severe 
reactions, such as displacement from or abandonment of high-quality 
habitat. Behavioral responses may include changing durations of 
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral 
activities (such as socializing or feeding); eliciting a visible 
startle response or aggressive behavior (such as tail/fin 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, 2019; Weilgart, 2007; Archer et al., 2010). Behavioral reactions 
can vary not only among individuals but also within an individual, 
depending on previous experience with a sound source, context, and 
numerous other factors (Ellison et al., 2012), and can vary depending 
on characteristics associated with the sound source (e.g., whether it 
is moving or stationary, number of sources, distance from the source). 
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. Please see Appendices B and C of Southall et 
al. (2007) and Gomez et al. (2016) for reviews of studies involving 
marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2004). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure.
    As noted above, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; Wartzok et al., 2004; National Research Council (NRC), 2005). 
Controlled experiments with captive marine mammals have showed 
pronounced behavioral reactions, including avoidance of loud sound 
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed 
responses of wild marine mammals to loud pulsed sound sources (e.g., 
seismic airguns) have been varied but often consist of avoidance 
behavior or other behavioral changes (Richardson et al., 1995; Morton 
and Symonds, 2002; Nowacek et al., 2007).
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior 
may reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.

[[Page 76599]]

    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 or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et 
al., 2007). For example, harbor porpoise' respiration rate increased in 
response to pile driving sounds at and above a received broadband SPL 
of 136 dB (zero-peak SPL: 151 dB re 1 [mu]Pa; SEL of a single strike: 
127 dB re 1 [mu]Pa\2\-s) (Kastelein et al., 2013).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Fristrup et al., 2003) or vocalizations (Foote et al., 2004), 
respectively, while North Atlantic right whales (Eubalaena glacialis) 
have been observed to shift the frequency content of their calls upward 
while reducing the rate of calling in areas of increased anthropogenic 
noise (Parks et al., 2007). In some cases, animals may cease sound 
production during production of aversive signals (Bowles et al., 1994).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Avoidance may be short-term, with animals returning to the area 
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; 
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). 
Longer-term displacement is possible, however, which may lead to 
changes in abundance or distribution patterns of the affected species 
in the affected region if habituation to the presence of the sound does 
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann 
et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996; Bowers et al., 2018). The result of a flight response 
could range from brief, temporary exertion and displacement from the 
area where the signal provokes flight to, in extreme cases, marine 
mammal strandings (England et al., 2001). However, it should be noted 
that response to a perceived predator does not necessarily invoke 
flight (Ford and Reeves, 2008), and whether individuals are solitary or 
in groups may influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fishes and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a 5-day period did not cause any sleep 
deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than 1 day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive (i.e., meaningful) behavioral reactions and multi-day 
anthropogenic activities. For example, just because an activity lasts 
for multiple days does not necessarily mean that individual animals are 
either exposed to activity-related stressors for multiple days or, 
further, exposed in a manner resulting in sustained multi-day 
substantive behavioral responses.
    Behavioral Reactions Observed at the POA. Specific to recent 
construction at the POA, behavioral reactions to pile driving have not 
been reported in non-CIBW species. During POA's PCT construction, 81 
harbor seals were observed within estimated Level B harassment zones 
associated with vibratory and impact installation and or removal of 36-
inch (61-cm) and 144-inch (366-cm) piles, and five harbor seals were 
observed within estimated Level A harassment zones during the 
installation of 144-inch (366-cm) piles. No observable behavioral 
reactions were observed in any of these seals (61N Environmental, 2021, 
2022a). One harbor porpoise was observed within the estimated Level B 
harassment zone during vibratory driving of a 36-inch (61-cm) pile in 
May 2021. The animal was travelling at a moderate pace. No observable 
reactions to pile driving were noted by the PSOs. Another harbor 
porpoise may have been within the

[[Page 76600]]

estimated Level B harassment zone during the impact installation of 36-
inch (61-cm) piles in June 2021, but PSOs did not record any behavioral 
responses of this individual to the pile driving activities. Similarly 
13 harbor seals observed within estimated Level B harassment zones 
associated with pile driving 36-inch (61-cm) piles during POA's SFD 
construction did not exhibit observable behavioral reactions (61N 
Environmental, 2022b).
    Specific to CIBWs, several years of marine mammal monitoring data 
demonstrate the behavioral responses to pile driving at the POA. 
Previous pile driving activities at the POA include the installation 
and removal of sheet piles, the vibratory and impact installation of 
24-inch (61-cm), 36-inch (91-cm), 48-in (122-cm), and 144-inch (366-cm) 
pipe piles, and the vibratory installation of 72-inch (183-cm) air 
bubble casings.
    Kendall and Cornick (2015) provide a comprehensive overview of 4 
years of scientific marine mammal monitoring conducted before (2005-
2006) and during the POA's MTR Project P (2008-2009). These were 
observations made by PSOs independent of the POA and their pile driving 
activities (i.e., not construction based PSOs). The authors 
investigated CIBW behavior before and during pile driving activity at 
the POA. Sighting rates, mean sighting duration, behavior, mean group 
size, group composition, and group formation were compared between the 
two periods. A total of about 2,329 hours of sampling effort was 
completed across 349 days from 2005 to 2009. Overall, 687 whales in 177 
groups were documented during the 69 days that whales were sighted. A 
total of 353 and 1,663 hours of pile driving took place in 2008 and 
2009, respectively. There was no relationship between monthly CIBW 
sighting rates and monthly pile driving rates (r = 0.19, p = 0.37). 
Sighting rates before (n = 12; 0.06  0.01) and during (n = 
13; 0.01  0.03) pile driving were not significantly 
different. However, sighting duration of CIBWs decreased significantly 
during pile driving (39  6 min before and 18  3 
min during). There were also significant differences in behavior before 
versus during pile driving. CIBWs primarily traveled through the study 
area both before and during pile driving; however, traveling increased 
relative to other behaviors during pile driving. Documentation of 
milling was observed on 21 occasions during pile driving. Mean group 
size decreased during pile driving; however, this difference was not 
statistically significant. In addition, group composition was 
significantly different before and during pile driving, with more white 
(i.e., likely older) animals being present during pile driving (Kendall 
and Cornick, 2015). CIBWs were primarily observed densely packed before 
and during pile driving; however, the number of densely packed groups 
increased by approximately 67 percent during pile driving. There were 
also significant increases in the number of dispersed groups 
(approximately 81 percent) and lone white whales (approximately 60 
percent) present during pile driving than before pile driving (Kendall 
and Cornick, 2015).
    During PCT and SFD construction monitoring, behaviors of CIBWs 
groups were compared by month and by construction activity (61N 
Environmental, 2021, 2022a, 2022b). Little variability was evident in 
the behaviors recorded from month to month, or between sightings that 
coincided with in-water pile installation and removal and those that 
did not (61N Environmental, 2021, 2022a). Definitive behavioral 
reactions to in-water pile driving or avoidance behaviors were not 
documented; however, potential reactions (where a group reversed its 
trajectory shortly after the start of in-water pile driving occurred; a 
group reversed its trajectory as it got closer to the sound source 
during active in-water pile driving; or upon an initial sighting, a 
group was already moving away from in-water pile driving, raising the 
possibility that it had been moving towards, but was only sighted after 
they turned away) and instances where CIBWs moved toward active in-
water pile driving were recorded. During these instances, impact 
driving appeared to cause potential behavioral reactions more readily 
than vibratory hammering (61N Environmental, 2021, 2022a, 2022b). One 
minor difference documented during PCT construction was a slightly 
higher incidence of milling behavior and diving during the periods of 
no pile driving and slightly higher rates of traveling behavior during 
periods when potential CIBW behavioral reactions to pile driving, as 
described above, were recorded (61N Environmental, 2021, 2022a). Note, 
narratives of each CIBW reaction can be found in the appendices of the 
POA's final monitoring reports (61N Environmental, 2021, 2022a, 2022b).
    Acoustically, Saxon-Kendall et al. (2013) recorded echolocation 
clicks (which can be indicative of feeding behavior) during the MTR 
Project at the POA both while pile driving was occurring and when it 
was not. This indicates that while feeding is not a predominant 
behavior observed in CIBWs sighted near the POA (61N Environmental, 
2021, 2022a, 2022b, 2022c; Easley-Appleyard and Leonard, 2022) CIBWs 
can and still exhibit feeding behaviors during pile driving activities. 
In addition, Castellote et al. (2020) found low echolocation detection 
rates in lower Knik Arm (i.e., Six Mile, Port MacKenzie, and Cairn 
Point) and suggested that CIBWs moved through that area relatively 
quickly when entering or exiting the Arm. No whistles or noisy 
vocalizations were recorded during the MTR construction activities; 
however, it is possible that persistent noise associated with 
construction activity at the MTR project masked beluga vocalizations 
and or that CIBWs did not use these communicative signals when they 
were near the MTR Project (Saxon-Kendall et al., 2013).
    Recently, McHuron et al. (2023) developed a model to predict 
general patterns related to the movement and foraging decisions of 
pregnant CIBWs in Cook Inlet. They found that the effects of 
disturbance from human activities, such as pile driving activities 
occurring at the POA assuming no prescribed mitigation measures 
implemented, are inextricably linked with prey availability. If prey 
are abundant during the summer and early fall, and prey during winter 
is above some critical threshold, pregnant CIBWs can likely cope with 
intermittent disruptions, such as those produced by pile driving at the 
POA (McHuron et al., 2023). However, they stress that more information 
needs to be acquired regarding CIBW prey and CIBW body condition, 
specifically in their critical habitat, to better understand possible 
behavioral responses to disturbance.
    Stress responses. An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Selye, 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

[[Page 76601]]

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.
    Norman (2011) reviewed environmental and anthropogenic stressors 
for CIBWs. Lyamin et al. (2011) determined that the heart rate of a 
beluga whale increases in response to noise, depending on the frequency 
and intensity. Acceleration of heart rate in the beluga whale is the 
first component of the ``acoustic startle response.'' Romano et al. 
(2004) demonstrated that captive beluga whales exposed to high-level 
impulsive sounds (i.e., seismic airgun and/or single pure tones up to 
201 dB RMS) resembling sonar pings showed increased stress hormone 
levels of norepinephrine, epinephrine, and dopamine when TTS was 
reached. Thomas et al. (1990) exposed beluga whales to playbacks of an 
oil-drilling platform in operation (``Sedco 708,'' 40 Hz-20 kHz; source 
level 153 dB). Ambient SPL at ambient conditions in the pool before 
playbacks was 106 dB and 134 to 137 dB RMS during playbacks at the 
monitoring hydrophone across the pool. All cell and platelet counts and 
21 different blood chemicals, including epinephrine and norepinephrine, 
were within normal limits throughout baseline and playback periods, and 
stress response hormone levels did not increase immediately after 
playbacks. The difference between the Romano et al. (2004) and Thomas 
et al. (1990) studies could be the differences in the type of sound 
(seismic airgun and/or tone versus oil drilling), the intensity and 
duration of the sound, the individual's response, and the surrounding 
circumstances of the individual's environment. The construction sounds 
in the Thomas et al. (1990) study would be more similar to those of 
pile installation than those in the study investigating stress response 
to water guns and pure tones. Therefore, no more than short-term, low-
hormone stress responses, if any, of beluga whales or other marine 
mammals are expected as a result of exposure to in-water pile 
installation and removal during the NES1 project.
    Auditory Masking. Since many marine mammals rely on sound to find 
prey, moderate social interactions, and facilitate mating (Tyack, 
2008), noise from anthropogenic sound sources can interfere with these 
functions, but only if the noise spectrum overlaps with the hearing 
sensitivity of the receiving marine mammal (Southall et al., 2007; 
Clark et al., 2009; Hatch et al., 2012). Chronic exposure to excessive, 
though not high-intensity, noise could cause masking at particular 
frequencies for marine mammals that utilize sound for vital biological 
functions (Clark et al., 2009). Acoustic masking is when other noises 
such as from human sources interfere 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). Therefore, under certain 
circumstances, marine mammals whose acoustical sensors or environment 
are being severely masked could also be impaired from maximizing their 
performance fitness in survival and reproduction. 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 (Hotchkin and 
Parks, 2013).
    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 human-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 (though not necessarily one 
that would be associated with harassment).
    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, 2010; 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 (Hotchkin and Parks, 2013). Masking can be 
tested directly in captive species (e.g., Erbe, 2008), but in wild 
populations it must be either modeled

[[Page 76602]]

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).
    Marine mammals at or near the proposed NES1 project site may be 
exposed to anthropogenic noise which may be a source of masking. 
Vocalization changes may result from a need to compete with an increase 
in background noise and include increasing the source level, modifying 
the frequency, increasing the call repetition rate of vocalizations, or 
ceasing to vocalize in the presence of increased noise (Hotchkin and 
Parks, 2013). For example, in response to loud noise, beluga whales may 
shift the frequency of their echolocation clicks to prevent masking by 
anthropogenic noise (Tyack, 2000; Eickmeier and Vallarta, 2022).
    Masking is more likely to occur in the presence of broadband, 
relatively continuous noise sources such as vibratory pile driving. 
Energy distribution of pile driving covers a broad frequency spectrum, 
and sound from pile driving would be within the audible range of 
pinnipeds and cetaceans present in the proposed action area. While some 
construction during the POA's activities may mask some acoustic signals 
that are relevant to the daily behavior of marine mammals, the short-
term duration and limited areas affected make it very unlikely that the 
fitness of individual marine mammals would be impacted.
    Airborne Acoustic Effects. Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with construction 
activities that have the potential to cause behavioral harassment, 
depending on their distance from these activities. Airborne noise would 
primarily be an issue for pinnipeds that are swimming or hauled out 
near the project site within the range of noise levels elevated above 
airborne acoustic harassment criteria. Although pinnipeds are known to 
haul-out regularly on man-made objects, we believe that incidents of 
take resulting solely from airborne sound are unlikely given there are 
no known pinniped haulout or pupping sites within the vicinity of the 
proposed project area; the nearest known pinniped haulout is located a 
minimum of 24 km south-southwest of Anchorage for harbor seals. 
Cetaceans are not expected to be exposed to airborne sounds that would 
result in harassment as defined under the MMPA.
    We recognize that pinnipeds in the water could be exposed to 
airborne sound that may result in behavioral harassment when looking 
with their heads above water. Most likely, airborne sound would cause 
behavioral responses similar to those discussed above in relation to 
underwater sound. For instance, anthropogenic sound could cause hauled-
out pinnipeds to exhibit changes in their normal behavior, such as 
reduction in vocalizations, or cause them to temporarily abandon the 
area and move further from the source. However, these animals would 
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.

Potential Effects on Marine Mammal Habitat

    The proposed project will occur within the same footprint as 
existing marine infrastructure. The nearshore and intertidal habitat 
where the proposed project will occur is an area of relatively high 
marine vessel traffic. Temporary, intermittent, and short-term habitat 
alteration may result from increased noise levels during the proposed 
construction activities. Effects on prey species will be limited in 
time and space.
    Removal of the North Extension bulkhead and impounded fill would 
result in restoration of subtidal and intertidal habitats that were 
lost when that structure was constructed in 2005-2011. Removal of 
approximately 1.35 million CY of fill material from below the high tide 
line would re-create approximately 0.05 km\2\ (13 acres) of intertidal 
and subtidal habitat, returning them to their approximate original 
slope and shoreline configuration. The proposed project area is not 
considered to be high-quality habitat for marine mammals or marine 
mammal prey, such as fish, and it is anticipated that the removal of 
the North Extension bulkhead would increase the amount of available 
habitat for both marine mammals and fish because they would be able to 
swim through the area at higher water levels. The area is expected to 
be of higher quality to marine mammals and fish as it returns to its 
natural state and is colonized by marine organisms.
    Water quality--Temporary and localized reduction in water quality 
would occur as a result of in-water construction activities. Most of 
this effect would occur during the installation and removal of piles 
when bottom sediments are disturbed. The installation and removal of 
piles would disturb bottom sediments and may cause a temporary increase 
in suspended sediment in the project area. During pile removal, 
sediment attached to the pile moves vertically through the water column 
until gravitational forces cause it to slough off under its own weight. 
The small resulting sediment plume is expected to 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 to turbidity and sedimentation are expected to be short-
term, minor, and localized. Since the currents are so strong in the 
area, following the completion of sediment-disturbing activities, 
suspended sediments 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, turbidity plumes 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 
available marine mammal habitat in Knik Arm.
    Potential Effects on Prey. Sound may affect marine mammals through 
impacts on the abundance, behavior, or distribution of prey species 
(e.g., crustaceans, cephalopods, fishes, zooplankton). Marine mammal 
prey varies by species, season, and location and, for some, is not well 
documented. Studies regarding the effects of noise on known marine 
mammal prey are described here.
    Fishes utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear

[[Page 76603]]

sounds using pressure and particle motion sensitivity capabilities and 
detect the motion of surrounding water (Fay et al., 2008). The 
potential effects of noise on fishes depends on the overlapping 
frequency range, distance from the sound source, water depth of 
exposure, and species-specific hearing sensitivity, anatomy, and 
physiology. Key impacts to fishes may include behavioral responses, 
hearing damage, barotrauma (pressure-related injuries), and mortality.
    Fish react to sounds that are especially strong and/or intermittent 
low-frequency sounds. 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 
fishes (e.g. Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). 
Several studies have demonstrated that impulsive sounds might affect 
the distribution and behavior of some fishes, potentially impacting 
foraging opportunities or increasing energetic costs (e.g., Fewtrell 
and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; 
Santulli et al., 1999; Paxton et al., 2017). However, some studies have 
shown no or slight reaction to impulse sounds (e.g., Pe[ntilde]a et 
al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et 
al., 2012). More commonly, though, the impacts of noise on fishes are 
temporary.
    During the POA's MTRP, the effects of impact and vibratory 
installation of 30-inch (76-cm) steel sheet piles at the POA on 133 
caged juvenile coho salmon in Knik Arm were studied (Hart Crowser 
Incorporated et al., 2009; Houghton et al., 2010). Acute or delayed 
mortalities, or behavioral abnormalities were not observed in any of 
the coho salmon. Furthermore, results indicated that the pile driving 
had no adverse effect on feeding ability or the ability of the fish to 
respond normally to threatening stimuli (Hart Crowser Incorporated et 
al., 2009; Houghton et al., 2010).
    SPLs of sufficient strength have been known to cause injury to 
fishes and fish mortality (summarized in Popper et al., 2014). 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 to 6 dB was recoverable within 24 hours for one species. Impacts 
would be most severe when the individual fish is close to the source 
and when the duration of exposure is long. Injury caused by barotrauma 
can range from slight to severe and can cause death, and is most likely 
for fish with swim bladders. Barotrauma injuries have been documented 
during controlled exposure to impact pile driving (Halvorsen et al., 
2012a; Casper et al., 2013, 2017).
    Fish populations in the proposed project area that serve as marine 
mammal prey could be temporarily affected by noise from pile 
installation and removal. The frequency range in which fishes generally 
perceive underwater sounds is 50 to 2,000 Hz, with peak sensitivities 
below 800 Hz (Popper and Hastings, 2009). Fish behavior or distribution 
may change, especially with strong and/or intermittent sounds that 
could harm fishes. High underwater SPLs have been documented to alter 
behavior, cause hearing loss, and injure or kill individual fish by 
causing serious internal injury (Hastings and Popper, 2005).
    Essential Fish Habitat (EFH) has been designated in the estuarine 
and marine waters in the vicinity of the proposed project area for all 
five species of salmon (i.e., chum salmon, pink salmon, coho salmon, 
sockeye salmon, and Chinook salmon; North Pacific Fishery Management 
Council (NPFMC), 2020, 2021), which are common prey of marine mammals, 
as well as for other species. (NPFMC, 2020). However, there are no 
designated habitat areas of particular concern in the vicinity of the 
Port, and therefore, adverse effects on EFH in this area are not 
expected.
    The greatest potential impact to fishes during construction would 
occur during impact pile removal. However, the use of impact pile 
driving would be limited to situations when sheet piles remain seized 
in the sediments and cannot be loosened or broken free with a vibratory 
hammer. Further, use of an impact hammer to dislodge piles is expected 
to be uncommon, with a limited number of up to 150 strikes (an 
estimated 50 strikes per pile for up to three piles) on any individual 
day or approximately 5 percent of active hammer duration for sheet 
pile. In-water construction activities would only occur during daylight 
hours, allowing fish to forage and transit the project area in the 
evening. Vibratory pile driving would possibly elicit behavioral 
reactions from fishes such as temporary avoidance of the area but is 
unlikely to cause injuries to fishes or have persistent effects on 
local fish populations. Construction also would have minimal permanent 
and temporary impacts on benthic invertebrate species, a marine mammal 
prey source. In addition, it should be noted that the area in question 
is low-quality habitat since it is already highly developed and 
experiences a high level of anthropogenic noise from normal operations 
and other vessel traffic at the POA.
    Fish species in Knik Arm, including those that are prey for marine 
mammals, are expected to benefit from removal of the North Extension 
bulkhead and availability of the resulting exposed subtidal and 
intertidal habitat. NES1 is not anticipated to impede migration of 
adult or juvenile salmon or to adversely affect the health and survival 
of the affected species at the population level. Once in-water pile 
installation and removal has ceased and NES1 is complete, the newly 
available habitat is expected to transition back to its original, more 
natural condition and provide foraging, migrating, and rearing habitats 
to fish and foraging habitat to marine mammals. In general, any 
negative impacts on marine mammal prey species are expected to be minor 
and temporary.

In-Water Construction Effects on Potential Foraging Habitat

    The NES1 Project area has not been considered to be high-quality 
habitat for marine mammals or marine mammal prey, such as fish, and it 
is anticipated that the long-term impact on marine mammals associated 
with NES1 would be a permanent increase in potential habitat because of 
the removal of the North Extension bulkhead, restoring access of the 
area to marine mammals and fish. The NES1 project is not expected to 
result in any habitat related effects that could cause significant or 
long-term negative consequences for individual marine mammals or their 
populations, since installation and removal of in-water piles would be 
temporary and intermittent, and the re-creation of intertidal and 
subtidal habitats would be permanent. Therefore, impacts of the project 
are not likely to have adverse effects on marine mammal foraging 
habitat in the proposed project area.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through the IHA, which will inform both 
NMFS' consideration of ``small numbers,'' and the negligible impact 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the

[[Page 76604]]

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

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021; Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB re 1 [mu]Pa 
for continuous (e.g., vibratory pile driving, drilling) and above RMS 
SPL 160 dB re 1 [mu]Pa for non-explosive impulsive (e.g., seismic 
airguns) or intermittent (e.g., scientific sonar) sources. Generally 
speaking, Level B harassment take estimates based on these behavioral 
harassment thresholds are expected to include any likely takes by TTS 
as, in most cases, the likelihood of TTS occurs at distances from the 
source less than those at which behavioral harassment is likely. TTS of 
a sufficient degree can manifest as behavioral harassment, as reduced 
hearing sensitivity and the potential reduced opportunities to detect 
important signals (conspecific communication, predators, prey) may 
result in changes in behavior patterns that would not otherwise occur.
    The POA's proposed activity includes the use of continuous 
(vibratory pile driving) and intermittent (impact pile driving) noise 
sources, and therefore the RMS SPL thresholds of 120 and 160 dB re 1 
[mu]Pa are applicable.
    Level A harassment. NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0; 
NMFS, 2018) identifies dual criteria to assess auditory injury (Level A 
harassment) to five different marine mammal groups (based on hearing 
sensitivity) as a result of exposure to noise from two different types 
of sources (impulsive or non-impulsive). The POA's proposed activity 
includes the use of impulsive (impact pile driving) and non-impulsive 
(vibratory driving) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 6--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing Group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.

[[Page 76605]]

 
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
  National Standards Institute standards (ANSI, 2013). However, peak sound pressure is defined by ANSI as
  incorporating frequency weighting, which is not the intent for NMFS' 2018 Technical Guidance. Hence, the
  subscript ``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted
  within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds
  indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW
  pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level
  thresholds could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle).
  When possible, it is valuable for action proponents to indicate the conditions under which these acoustic
  thresholds will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the proposed project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., impact pile removal and 
vibratory pile installation and removal). Calculation of the area 
ensonified by the proposed action is dependent on the background sound 
levels at the project site, the source levels of the proposed 
activities, and the estimated transmission loss coefficients for the 
proposed activities at the site. These factors are addressed in order, 
below.
    Background Sound Levels at the Port of Alaska. As noted in the 
Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat Section of this notice, the POA is an industrial facility in a 
location with high levels of commercial vessel traffic, port operations 
(including dredging), and extreme tidal flow. Previous measurements of 
background noise at the POA have recorded a background SPL of 122.2 dB 
RMS (Austin et al., 2016). NMFS concurs that this SPL reasonably 
represents background noise near the proposed project area, and 
therefore we have used 122.2 dB RMS as the threshold for Level B 
harassment (instead of 120 dB RMS).
    Sound Source Levels 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. In 
order to calculate the distances to the Level A harassment and the 
Level B harassment sound thresholds for the methods and piles being 
used in this project, the POA used acoustic monitoring data from sound 
source verification studies to develop proxy source levels for the 
various pile types, sizes and methods (Table 7). While site-specific 
sound source verification studies have been conducted at the POA, the 
vast majority of the measurements recorded in those studies were made 
when bubble curtains were deployed around the sound source, which act 
to attenuate sound levels (Austin et al., 2016; I&R, 2021a, 2021b). 
Bubble curtains are not a feasible mitigation measure for the NES1 
project due to the demolition and sequencing nature of the project (see 
the Proposed Mitigation section of this notice for additional 
discussion), and therefore the majority of the proposed proxy values 
for this project are based on measurements recorded from locations 
other than the POA.
    Underwater sound was measured in 2008 at the POA for the MTRP 
during installation of sheet piles to assess potential impacts of sound 
on marine species. Sound levels for installation of sheet piles 
measured at 10 m typically ranged from 147 to 161 dB RMS, with a mean 
of approximately 155 dB RMS (James Reyff, unpublished data). An SSL of 
162 dB RMS was reported in (CALTRANS, 2020) summary tables for 24-inch 
steel sheet piles. This is a more rigid type of sheet pile that 
requires a large vibratory driver (James Reyff, personal communication, 
August 26, 2020). Based on the 2008 measurements at the POA and the 
CALTRANS data, a value of 160 dB RMS was assumed for vibratory removal 
of sheet piles.
    NMFS concurs that the source levels proposed by the POA for all 
pile sizes during impact hammering activities and vibratory 
installation of all pile types are appropriate to use for calculating 
harassment isopleths for the POA's proposed NES1 activities (Table 7). 
However, the source levels proposed by the POA for vibratory pile 
removal were based on limited data collected at the POA. Therefore, 
NMFS considered and evaluated all data related to unattenuated 
vibratory removal of 24-inch (61-cm) and 36-inch (91-cm) steel pipe 
piles available, including sound source verification data measured at 
the POA during the PCT project (Reyff et al, 2021a) and elsewhere 
(i.e., Coleman, 2011; U.S. Navy, 2012; I&R, 2017). NMFS gathered data 
from publicly available reports that reported driving conditions and 
specified vibratory removal for certain piles. If vibratory removal was 
not specifically noted for a given pile, we excluded that data from the 
analysis. Mean RMS SPLs reported by these studies were converted into 
pressure values, and pressure values for piles from each project were 
averaged to give a single SPL for each project. The calculated project 
means were then averaged and converted back into dBs to give a single 
recommended SPL for each pile type.
    Ten measurements were available for unattenuated vibratory removal 
of 24-inch (61-cm) piles: 3 from Columbia River Crossing in Oregon 
(mean RMS SPL of 172.4 dB; Coleman, 2011), 5 from Joint Expeditionary 
Base Little Creek in Norfolk, Virginia (mean RMS SPL of 148.2 dB; I&R, 
2017), and 2 from the PCT project at the POA (mean RMS SPL of 168.7 dB; 
I&R, 2021a, 2023). The calculated average SPL for unattenuated 
vibratory removal of 24-inch (61-cm) steel pipe piles from these 
studies was 168 dB RMS (Table 7). Forty measurements were available for 
unattenuated vibratory removal of 36-inch (91-cm) piles: 38 from the 
U.S. Navy Test Pile Program at Naval Base Kitsap in Bangor, Washington 
(mean RMS SPL of 159.4 dB; U.S. Navy, 2012), and 2 from the PCT project 
at the POA (mean RMS SPL of 158.5 dB; I&R, 2021, 2023). The calculated 
average SPL for unattenuated vibratory removal of 36-inch (91-cm) steel 
pipe piles from these studies was 159 dB RMS (Table 7). Note that the 
proxy values in Table 7 represent SPL referenced at a distance of 10 m 
from the source. Interestingly, the RMS SPLs for the unattenuated 
vibratory removal of 24-inch (61-cm) piles was much louder than the 
unattenuated vibratory removal of 36-inch piles (91-cm), and even 
louder than the unattenuated vibratory installation of 24-inch piles. 
I&R (2023) suggest that at least for data recorded at the POA, the 
higher 24-inch (61-cm) removal levels are likely due to the piles being 
removed at rates of 1,600 to 1,700 revolutions per minute (rpm), while 
36-inch (91-cm) piles, which are significantly heavier than 24-inch 
(61-cm) piles), were removed at a rate of 1,900 rpm. The slower rates 
combined with the lighter piles would cause the hammer to easily 
``jerk'' or excite the 24-inch (61-cm) piles as they were extracted, 
resulting in a louder rattling sound and louder sound levels. This did 
not occur for the 36-inch (91-cm) piles, which were considerably 
heavier due to

[[Page 76606]]

increased diameter, longer length, and greater thickness.

                       Table 7--Summary of Unattenuated In-Water Pile Driving Proxy Levels
                                                    [at 10 m]
----------------------------------------------------------------------------------------------------------------
                                Installation or  Peak SPL (re 1   RMS SPL (re 1     SEL (re 1
          Pile type                 removal          [mu]Pa)         [mu]Pa)     [mu]Pa\2\-sec)       Source
----------------------------------------------------------------------------------------------------------------
Impact driving:
    Sheet pile...............  Removal.........             205             189             179  CALTRANS
                                                                                                  (2020).
Vibratory driving:
    Sheet pile...............  Removal (hammer               NA             160              NA  CALTRANS (2015,
                                or splitter).                                                     2020).
    24-inch (61-cm) steel      Installation....                             161                  U.S. Navy
     pipe.                                                                                        (2015).
                               Removal.........                             168                  Coleman (2011),
                                                                                                  I&R (2017,
                                                                                                  2021, 2023).
    36-inch (91-cm steel       Installation....                             166                  U.S. Navy
     pipe).                                                                                       (2015).
                               Removal.........                             159                  U.S. Navy
                                                                                                  (2012), I&R
                                                                                                  (2021, 2023).
----------------------------------------------------------------------------------------------------------------

    The POA assumes that a pile splitter would produce the same or 
similar sound levels as a vibratory hammer without the splitter 
attachment; therefore, the POA combined use of a vibratory hammer to 
remove sheet pile and use of a splitter into a single category (i.e., 
vibratory hammer removal). NMFS is currently unaware of any 
hydroacoustic measurements of pile splitting with a vibratory hammer. 
Without additional data, NMFS preliminary accepts the POAs proposed 
SPLs and assessments. However, NMFS specifically requests comments on 
the proposed SPL values for vibratory pile splitting. If available, 
NMFS requests recommendations for available data on underwater 
measurements and potential impacts of these construction activities.
    Transmission Loss. For unattenuated impact pile driving, the POA 
proposed to use 15 as the TL coefficient, meaning they assume practical 
spreading loss (i.e., the POA assumes TL = 15*Log10(range)); 
NMFS concurs with this value and has used the practical spreading loss 
model for impact driving in this analysis.
    The TL coefficient that the POA proposed for unattenuated vibratory 
installation and removal of piles is 16.5 (i.e., TL = 
16.5*Log10(range)). This value is an average of measurements 
obtained from two 48-in (122-cm) piles installed via an unattenuated 
vibratory hammer in 2016 (Austin et al., 2016). To assess the 
appropriateness of this TL coefficient to be used for the proposed 
project, NMFS examined and analyzed additional TL measurements recorded 
at the POA. This includes a TL coefficient of 22 (deep hydrophone 
measurement) from the 2004 unattenuated vibratory installation of one 
36-inch (91-cm) pile in Knik Arm (Blackwell, 2004), as well as TL 
coefficients ranging from 10.3 to 18.2 from the unattenuated vibratory 
removal of 24-inch (61 cm) and 36-inch (91-cm) piles and the 
unattenuated vibratory installation of one 48-in (122-cm) pile at the 
POA in 2021 (I&R 2021, 2023). To account for statistical 
interdependence due to temporal correlations and equipment issues 
across projects, values were averaged first within each individual 
project, and then across projects. The mean and median value of the 
measured TL coefficients for unattenuated vibratory piles in Knik Arm 
by project are equal to 18.9 and 16.5, respectively. NMFS proposes the 
use of the project median TL coefficient of 16.5 during unattenuated 
vibratory installation and removal of all piles during the NES1 
project. This value is representative of all unattenuated vibratory 
measurements in the Knik Arm. Further, 16.5 is the mean of the 2016 
measurements, which were made closer to the NES1 proposed project area 
than other measurements and were composed of measurements from multiple 
directions (both north and south/southwest).
    Estimated Harassment Isopleths. All estimated Level B harassment 
isopleths are reported in Table 9. At POA, Level B harassment isopleths 
from the proposed project will be limited by the coastline along Knik 
Arm along and across from the project site. The maximum predicted 
isopleth distance is 5,968 m during vibratory removal of 24-inch (61-
cm) steel pipe piles.
    The ensonified area associated with Level A harassment is more 
technically challenging to predict due to the need to account for a 
duration component. Therefore, NMFS developed an optional User 
Spreadsheet tool to accompany the Technical Guidance that can be used 
to relatively simply predict an isopleth distance for use in 
conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. For 
stationary sources such as pile driving, the optional User Spreadsheet 
tool predicts the distance at which, if a marine mammal remained at 
that distance for the duration of the activity, it would be expected to 
incur PTS. Inputs used in the User Spreadsheet are reported in Table 8 
and the resulting isopleths and ensonified areas are reported in Table 
9.

[[Page 76607]]



                                                          Table 8--NMFS User Spreadsheet Inputs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                      Impact pile                                           Vibratory pile driving
                                        driving      ---------------------------------------------------------------------------------------------------
                                 --------------------     Sheet pile            24-inch (61-cm) steel pipe              36-inch (91-cm) steel pipe
                                      Sheet pile     ---------------------------------------------------------------------------------------------------
                                 --------------------
                                        Removal             Removal          Installation           Removal          Installation           Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used............  E.1) Impact pile    A.1) Non-Impul,     A.1) Non-Impul,     A.1) Non-Impul,     A.1) Non-Impul,     A.1) Non-Impul,
                                   driving.            Stat, Cont.         Stat, Cont.         Stat, Cont.         Stat, Cont.         Stat, Cont.
Source Level (SPL)..............  179 dB SEL........  160 dB RMS........  161 dB RMS........  168 dB RMS........  166 dB RMS........  159 dB RMS.
Transmission Loss Coefficient...  15................  16.5..............  16.5..............  16.5..............  16.5..............  16.5.
Weighting Factor Adjustment       2.................  2.5...............  2.5...............  2.5...............  2.5...............  2.5.
 (kHz).
Time to install/remove single     ..................  5.................  15................  15................  15................  15.
 pile (minutes).
Number of strikes per pile......  50
Piles per day...................  3.................  24................  12................  12................  12................  12.
Distance of sound pressure level  10................  10................  10................  10................  10................  10.
 measurement (m).
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                         Table 9--Calculated Distance and Areas of Level A and Level B Harassment Per Pile Type and Pile Driving Method
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                      Level A harassment distance (m)                              Level B           Level B
                                                                             --------------------------------------------------------------------------------    harassment     harassment  area
                  Activity                            Pile type/size                                                                                          distance (m) all     (km\2\) all
                                                                                    LF              MF              HF              PW              OW         hearing groups    hearing groups
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Removal..............................  Sheet pile....................             153               6             182              82               6               858              1.44
Vibratory Installation......................  24-inch (61-cm)...............              14               2              20               9               1             2,247              8.39
                                              36-inch (91-cm)...............              28               4              40              18               2             4,514             26.13
Vibratory or Splitter Removal...............  Sheet pile....................              10               1              14               6               1             1,954              6.47
Vibratory Removal...........................  24-inch (61-cm)...............              37               4              53              24               3             5,968             37.64
                                              36-inch (91-cm)...............              11               2              15               7               1             1,700              4.99
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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 calculation. We also describe how the information 
provided above is synthesized to produce a quantitative estimate of the 
take that is reasonably likely to occur and proposed for authorization.
Gray Whale
    Sightings of gray whales in the proposed project area are rare. 
Few, if any, gray whales are expected to approach the proposed project 
area. However, based on three separate sightings of single gray whales 
near the POA in 2020 and 2021 (61N Environmental, 2021, 2022a; Easley-
Appleyard and Leonard, 2022), the POA anticipates that up to six 
individuals could be within estimated harassment zones during NES1 
project activities. Therefore, NMFS proposes to authorize six takes by 
Level B harassment for gray whales during the NES1 project. Take by 
Level A harassment is not anticipated or proposed to be authorized. The 
Level A harassment zones (Table 9) are smaller than the required 
shutdown zones (see the Proposed Mitigation section). It is unlikely 
that a gray whale would enter and remain within the Level A harassment 
zone long enough to incur PTS.
Humpback Whale
    Sightings of humpback whales in the proposed project area are rare, 
and few, if any, humpback whales are expected to approach the proposed 
project area. However, there have been a few observations of humpback 
whales near the POA as described in the Description of Marine Mammals 
in the Area of Specified Activities section of this notice. Based on 
the two sightings in 2017 of what was likely a single individual at the 
Anchorage Public Boat Dock at Ship Creek (ABR, Inc., 2017) south of the 
Project area, the POA requested authorization of six takes of humpback 
whales. However, given the maximum number of humpback whales observed 
within a single construction season was two (in 2017), NMFS instead 
anticipates that only up to four humpback whales could be exposed to 
project-related underwater noise during the NES1 project. Therefore, 
NMFS proposes to authorize four takes by Level B harassment for 
humpback whales during the NES1 project. Take by Level A harassment is 
not anticipated or proposed to be authorized. The Level A harassment 
zones (Table 9) are smaller than the required shutdown zones (see the 
Proposed Mitigation section), therefore, it is unlikely that a humpback 
whale would enter and remain within the Level A harassment zone long 
enough to incur PTS.
Killer Whale
    Few, if any, killer whales are expected to approach the NES1 
project area. No killer whales were sighted during previous monitoring 
programs for POA construction projects, including the 2016 TPP, 2020 
PCT, and 2022 SFD projects (Prevel-Ramos et al., 2006; Markowitz and 
McGuire, 2007; Cornick and Saxon-Kendall, 2008, 2009; Cornick et al., 
2010, 2011; ICRC, 2009, 2010, 2011, 2012; Cornick and Pinney, 2011;

[[Page 76608]]

Cornick and Seagars, 2016; 61N Environmental, 2021, 2022b), until PCT 
construction in 2021, when two killer whales were sighted (61N 
Environmental, 2022a). Previous sightings of transient killer whales 
have documented pod sizes in upper Cook Inlet between one and six 
individuals (Shelden et al., 2003). Therefore, the POA conservatively 
estimates that no more than one small pod (assumed to be six 
individuals) could be within estimated harassment zones during NES1 
project activities.
    Take by Level A harassment is not anticipated or proposed to be 
authorized due to the implementation of shutdown zones, which would be 
larger than the Level A harassment zones (described below in the 
Proposed Mitigation section), and the low likelihood that killer whales 
would approach this distance for sufficient duration to incur PTS. 
Therefore, NMFS proposes to authorize six takes by Level B harassment 
for killer whales.
Harbor Porpoise
    Monitoring data recorded from 2005 through 2022 were used to 
evaluate hourly sighting rates for harbor porpoises in the proposed 
NES1 area (see Table 4-3 in the POA's application). During most years 
of monitoring, no harbor porpoises were observed. However, there has 
been an increase in harbor porpoise sightings in upper Cook Inlet in 
recent decades (e.g., 61N Environmental, 2021, 2022a; Shelden et al., 
2014). The highest sighting rate for any recorded year during in-water 
pile installation and removal was an average of 0.037 harbor porpoises 
per hour during PCT construction in 2021, when observations occurred 
across most months. Given the uncertainty around harbor porpoise 
occurrence at the POA and potential that occurrence is increasing, it 
is estimated that approximately 0.07 harbor porpoises per hour (the 
2021 rate of 0.037 harbor porpoises per hour doubled) may be observed 
near the proposed NES1 area per hour of hammer use. With 246.5 hours of 
in-water pile installation and removal, we estimate that there could be 
18 instances where harbor porpoises (0.07 harbor porpoises per hour * 
246.5 hours = 17.3 harbor porpoises rounded up to 18 harbor porpoises) 
could be within estimated harassment zones during NES1 project 
activities.
    Harbor porpoises are small, lack a visible blow, have low dorsal 
fins, an overall low profile, and a short surfacing time, making them 
difficult to observe (Dahlheim et al., 2015). To account for the 
possibility that a harbor porpoise could enter a Level A harassment 
zone and remain there for sufficient duration to incur PTS before 
activities were shut down, the POA assumed that 5 percent of estimated 
harbor porpoise takes (one take of harbor porpoise; 5 percent of 18 = 
0.9, rounded up to 1) could be taken by Level A harassment. In its 
request, the POA rounded this estimate up to two to account for the 
average group size of this species, However, NMFS has determined such 
adjustments are generally unnecessary for purposes of estimating 
potential incidents of Level A harassment and does not concur with the 
request. At relatively close distances, NMFS believes it unlikely that 
groups will necessarily adhere to each other for sufficient duration 
for the entire group to incur PTS. While it is unlikely that a harbor 
porpoise could enter a Level A harassment zone for sufficient duration 
to incur PTS given the proposed shutdown measures (see the Proposed 
Mitigation section for more information) and potential for avoidance 
behavior, this species moves quickly and can be difficult to detect and 
track, therefore, NMFS proposes to authorize 1 take by Level A 
harassment and 17 takes by Level B harassment for harbor porpoises, for 
a total of 18 instances of take.
Steller Sea Lion
    Steller sea lions are anticipated to occur in low numbers within 
the proposed NES1 project area as summarized in the Description of 
Marine Mammals in the Area of Specified Activities section. Similar to 
the approach used above for harbor porpoises, the POA used previously 
recorded sighting rates of Steller sea lions near the POA to estimate 
requested take for this species. During SFD construction in May and 
June of 2022, the hourly sighting rate for Steller sea lions was 0.028. 
The hourly sighting rate for Steller sea lions in 2021, the most recent 
year with observations across most months, was approximately 0.01. 
Given the uncertainty around Steller sea lion occurrence at the POA and 
potential that occurrence is increasing, the POA estimated that 
approximately 0.06 Steller sea lions per hour (the May and June 2022 
rate of 0.028 Steller sea lions per hour doubled) may be observed near 
the proposed NES1 project areas per hour of hammer use. With 246.5 
hours of in-water pile installation and removal, the POA estimates that 
15 Steller sea lions (0.06 sea lions per hour * 246.5 hours = 14.79 sea 
lions rounded up to 15) could be within estimated harassment zones 
during NES1 project activities. However, the highest number of Steller 
sea lions that have been observed during the 2020-2022 monitoring 
efforts at the POA was nine individuals (eight during PCT Phase 1 
monitoring and one during NMFS 2021 monitoring). Given the POA's 
estimate assumes a higher Steller sea lion sighting rate (0.06) than 
has been observed at the POA and results in an estimate that is much 
larger than the number of Steller sea lions observed in a year, NMFS 
believes that the 15 estimated takes requested by the POA overestimates 
potential exposures of this species. NMFS instead proposed that nine 
Steller sea lions may be taken, by Level B harassment only, during the 
NES1 project.
    The largest Level A harassment zone for Steller sea lions is 6 m. 
While it is unlikely that a Steller sea lion would enter a Level A 
harassment zone for sufficient duration to incur PTS, the POA is aware 
of a Steller sea lion that popped up next to a work skiff during the 
TPP in 2016, which was documented as a potential take by Level A 
harassment by the PSOs on duty at the time. Pile driving, however, was 
not occurring at the time the event was recorded and a brief 
observation of an animal within a Level A harassment zone does not 
necessarily mean the animal experienced Level A harassment (other 
factors such as duration within the harassment zone need to be taken 
into consideration). However, as a result of the aforementioned event, 
the POA requested authorization of an additional two takes of Steller 
sea lions by Level A harassment. Given the small Level A harassment 
zone (6 m), and proposed shutdown zones of >= 10 m, NMFS believes that 
it is unlikely that a Steller sea lion would be within the Level A 
harassment zone for sufficient duration to incur PTS. Therefore, NMFS 
does not propose to authorize take by Level A harassment for Steller 
sea lions. Rather, all 9 estimated takes are assumed to occur by Level 
B harassment, and no take by Level A harassment is proposed for 
authorization.
Harbor Seal
    No known harbor seal haulout or pupping sites occur in the vicinity 
of the POA. In addition, harbor seals are not known to reside in the 
proposed NES1 project area, but they are seen regularly near the mouth 
of Ship Creek when salmon are running, from July through September. 
With the exception of newborn pups, all ages and sexes of harbor seals 
could occur in the NES1 project area. Any harassment of harbor seals 
during in-water pile installation and removal would involve a limited 
number of individuals that may

[[Page 76609]]

potentially swim through the NES1 project area or linger near Ship 
Creek.
    The POA evaluated marine mammal monitoring data to calculate hourly 
sighting rates for harbor seals in the NES1 project area (see Table 4-1 
in the POA's application). Of the 524 harbor seal sightings in 2020 and 
2021, 93.7 percent of the sightings were of single individuals; only 
5.7 percent of sightings were of two individual harbor seals, and only 
0.6 percent of sightings reported three harbor seals. Sighting rates of 
harbor seals were highly variable and appeared to have increased during 
monitoring between 2005 and 2022. It is unknown whether any potential 
increase was due to local population increases or habituation to 
ongoing construction activities. The highest individual hourly sighting 
rate recorded for a previous year was used to quantify take of harbor 
seals for in-water pile installation and removal associated with NES1. 
This occurred in 2021 during PCT Phase 2 construction, when harbor 
seals were observed from May through September. A total of 220 harbor 
seal sightings were observed over 734.9 hours of monitoring, at an 
average rate of 0.30 harbor seal sightings per hour. The maximum 
monthly sighting rate occurred in September 2020 and was 0.51 harbor 
seal sightings per hour. Based on these data, the POA estimated that 
approximately one harbor seal (the maximum monthly sighting rate (0.51) 
rounded up) may be observed near the NES1 project per hour of hammer 
use. This approximate sighting rate of one harbor seal per hour was 
also used to calculate potential exposures of harbor seals for the SFD 
project (86 FR 50057, September 7, 2021). Therefore, the POA estimates 
that during the 246.5 hours of anticipated in-water pile installation 
and removal, up to 247 harbor seals (1 harbor seal per hour * 246.5 
hours = 246.5 harbor seals, rounded up to 247) could be within 
estimated harassment zones.
    Harbor seals often appear curious about onshore activities and may 
approach closely. The mouth of Ship Creek, where harbor seals linger, 
is about 2,500 m from the southern end of the NES1 and is therefore 
outside of the Level A harassment zones calculated for harbor seals 
(Table 9). However, given the potential difficulty of tracking 
individual harbor seals along the face of the NES1 site and their 
consistent low-level use of the POA area, NMFS anticipates the 
potential for some take by Level A harassment for harbor seals. For the 
SFD project, NMFS authorized 8.6 percent of estimated harbor seal takes 
as potential Level A harassment based on the proportion of previous 
harbor seal sightings within the estimated Level A harassment zones (86 
FR 50057, September 7, 2021), but the NES1 Project is more distant from 
Ship Creek than SFD. NMFS therefore anticipates that a smaller 
proportion of takes by Level A harassment may occur during the NES1 
project, and proposes to reduce this percentage to 5 percent. 
Therefore, NMFS proposes to authorize 13 harbor seal takes (5 percent 
of 247 exposures) by Level A harassment and 234 takes (247 potential 
exposures minus 13) by Level B harassment, for a total of 247 takes.
Beluga Whale
    For the POA's PCT and SFD projects, NMFS used a sighting rate 
methodology to calculate potential exposure (equated to take) of CIBWs 
to sound levels above harassment criteria produced by the POA's 
construction activities (85 FR 19294, April 6, 2020; 86 FR 50057, 
September 7, 2021, respectively). For the PCT project, NMFS used data 
collected during marine mammal observations from 2005 to 2009 (Kendall 
and Cornick, 2015) and the total number of monthly observation hours 
during these efforts to derive hourly sighting rates of CIBWs per month 
of observation (April through November) (85 FR 19294, April 6, 2020). 
For the SFD project, observation data from 2020 PCT construction were 
also incorporated into the analysis (86 FR 50057, September 7, 2021; 
61N Environmental, 2021).
    The marine mammal monitoring programs for the PCT and SFD projects 
produced a unique and comprehensive data set of CIBW locations and 
movements (table 10; 61N Environmental, 2021, 2022a, 2022b; Easley-
Appleyard and Leonard, 2022) that is the most current data set 
available for Knik Arm. During the PCT and SFD projects, the POA's 
marine mammal monitoring programs included 11 PSOs working from four 
elevated, specially designed monitoring stations located along a 9-km 
stretch of coastline surrounding the POA. The number of days data was 
collected varied among years and project, with 128 days during PCT 
Phase 1 in 2020, 74 days during PCT Phase 2 in 2021, and 13 days during 
SFD in 2022 (see Table 6-7 in the POA's application for additional 
information regarding CIBW monitoring data). PSOs during these projects 
used 25-power ``big-eye'' and hand-held binoculars to detect and 
identify marine mammals, and theodolites to track movements of CIBW 
groups over time and collect location data while they remained in view.
    These POA monitoring programs were supplemented in 2021 with a 
NMFS-funded visual marine mammal monitoring project that collected data 
during non-pile driving days during PCT Phase 2 (table 10; Easley-
Appleyard and Leonard, 2022). NMFS replicated the POA monitoring 
efforts, as feasible, including use of 2 of the POA's monitoring 
platforms, equipment (Big Eye binoculars, theodolite, 7x50 reticle 
binoculars), data collection software, monitoring and data collection 
protocol, and observers; however, the NMFS-funded program utilized only 
4 PSOs and 2 observation stations along with shorter (4- to 8-hour) 
observation periods compared to PCT or SFD data collection, which 
included 11 PSOs, 4 observation stations, and most observation days 
lasting close to 10 hours. Despite the differences in effort, the NMFS 
dataset fills in gaps during the 2021 season when CIBW presence began 
to increase from low presence in July and is thus valuable in this 
analysis. NMFS' PSO's monitored for 231.6 hours on 47 non-consecutive 
days in July, August, September, and October.
    Distances from CIBW sightings to the project site from the POA and 
NMFS-funded monitoring programs ranged from less than 10 m up to nearly 
15 km during these monitoring programs. These robust marine mammal 
monitoring programs in place from 2020 through 2022 located, 
identified, and tracked CIBWs at greater distances from the proposed 
project site than previous monitoring programs (i.e., Kendall and 
Cornick, 2015), and has contributed to a better understanding of CIBW 
movements in upper Cook Inlet (e.g., Easley-Appleyard and Leonard, 
2022).
    Given the evolution of the best available data of CIBW presence in 
upper Cook Inlet, particularly regarding the distances at which CIBWs 
were being observed and documented (which increased during the PCT and 
SFD compared to earlier monitoring efforts), the POA proposes, and NMFS 
concurs, that the original sighting rate methodology used for the PCT 
and SFD projects is no longer the best approach for calculating 
potential take of CIBWs for the NES1 project. The recent and 
comprehensive data set of CIBW locations and movements from the PCT and 
SFD projects (61N Environmental, 2021, 2022a, 2022b; Easley-Appleyard 
and Leonard, 2022) provides the opportunity for refinement of the 
previously used sighting rate methodology with updated data. Data for 
2020, 2021, and 2022 were selected for the updated sighting rate 
analysis for the NES1 proposed project because they are the most 
current data available and are therefore most likely to accurately

[[Page 76610]]

represent future CIBW occurrence at the proposed project site, which 
may be affected by CIBW population size, CIBW movement patterns through 
Knik Arm, environmental change (including climate change), differences 
in salmon and other prey abundance among years, and other factors 
(table 10). The data from 2005 to 2009 (Kendall and Cornick, 2015), 
which was used by NMFS for sighting rate analyses for the PCT and SFD 
IHAs, were not included in this analysis due to the changes in 
observation programs and age of the data collected. Monitoring data 
from the 2016 TPP (Cornick and Seagars, 2016) were also not included in 
the analysis because of limited hours observed, limited seasonal 
coverage, and differences in the observation programs.

                Table 10--Marine Mammal Monitoring Data Used for CIBW Sighting Rate Calculations
----------------------------------------------------------------------------------------------------------------
                            Monitoring type and data       Number of CIBW     Number of CIBW
          Year                       source                 group fixes           groups        Number of CIBWs
----------------------------------------------------------------------------------------------------------------
2020...................  PCT: POA Construction                       2,653                245                987
                          Monitoring.
                         61N Environmental, 2021.......
2021...................  PCT: NMFS Monitoring..........                694             \1\109                575
                         Easley-Appleyard and Leonard,
                          2022.
2021...................  PCT: POA Construction                       1,339                132                517
                          Monitoring.
                         61N Environmental, 2021, 2022a
2022...................  SFD: POA Construction                         151                  9                 41
                          Monitoring.
                         61N Environmental, 2022b......
----------------------------------------------------------------------------------------------------------------
\1\ This number differs slightly from Table 6-8 in the POA's application due to our removal of a few duplicate
  data points in the NMFS data set.

    The sighting rate methodology used for the PCT (85 FR 19294, April 
6, 2020) and SFD (86 FR 50057, September 7, 2021) projects used 
observations of CIBWs recorded in Knik Arm, regardless of observation 
distance to the POA, to produce a single monthly sighting rate that was 
then used to calculate potential CIBW take for all activities, 
regardless of the size of the ensonified areas for the project 
activities (i.e., take was calculated solely based on the monthly 
sighting rates and the estimated hours of proposed activities, and did 
not consider the estimated sizes of the ensonified areas). This method 
may have overestimated potential CIBW takes when harassment zones were 
small because distant CIBWs would have been included in the sighting 
rate. This method also resulted in takes estimates that were identical 
for installation and removal of all pile sizes, regardless of pile 
driving method used (e.g., vibratory, impact) or implementation of 
attenuation systems, since the calculation did not consider the size of 
the ensonified areas.
    NMFS and the POA collaboratively developed a new sighting rate 
methodology for the NES1 project that incorporates a spatial component 
for CIBW observations, which would allow for more accurate estimation 
of potential take of CIBWs for this project. NMFS proposes to use this 
approach to estimate potential takes of CIBW for authorization. During 
the POA's and NMFS' marine mammal monitoring programs for the PCT and 
SFD projects, PSOs had an increased ability to detect, identify, and 
track CIBWs groups at greater distances from the project work site when 
compared with previous years because of the POA's expanded monitoring 
program as described above. This meant that observations of CIBWs in 
the 2020-2022 dataset (table 10) include sightings of individuals at 
distances far outside the ensonified areas estimated for the NES1 
project (Table 9). Therefore, it would not be appropriate to group all 
CIBW observations from these datasets into a single sighting rate as 
was done for the PCT and SFD projects. Rather, we propose that CIBW 
observations should be considered in relation to their distance to the 
NES1 project site when determining appropriate sighting rates to use 
when estimating take for this project. This would help to ensure that 
the sighting rates used to estimate take are representative of CIBW 
presence in the proposed ensonified areas.
    To incorporate a spatial component into the sighting rate 
methodology, the POA calculated each CIBW group's closest point of 
approach (CPOA) relative to the NES1 proposed project site. The 2020-
2022 marine mammal monitoring programs (table 10) enabled the 
collection, in many cases, of multiple locations of CIBW groups as they 
transited through Knik Arm, which allowed for track lines to be 
interpolated for many groups. The POA used these track lines, or single 
recorded locations in instances where only one sighting location was 
available, to calculate each group's CPOA. CPOAs were calculated in 
ArcGIS software using the GPS coordinates provided for documented 
sightings of each group (for details on data collection methods, see 
61N Environmental, 2021, 2022a, 2022b; Easley-Appleyard and Leonard, 
2022) and the NES1 location midpoint, centered on the proposed project 
site. A CIBW group was defined as a sighting of one or more CIBWs as 
determined during data collection. The most distant CPOA location to 
NES1 was 11,057 m and the closest CPOA location was 15 m.
    The cumulative density distribution of CPOA values represents the 
percentage of CIBW observations that were within various distances to 
the NES1 action site (Figure 2). This distribution shows how CIBW 
observations differed with distances to the NES1 site and was used to 
infer appropriate distances within which to estimate spatially-derived 
CIBW sighting rates (Figure 2). The POA implemented a piecewise 
regression model that detected breakpoints (i.e., points within the 
CPOA data at which statistical properties of the sequence of 
observational distances changed) in the cumulative density distribution 
of the CPOA locations, which they proposed to represent spatially-based 
sighting rate bins for use in calculating CIBW sighting rates. The POA 
used the ``Segmented'' package (Muggeo, 2020) in the R Statistical 
Software Package (R Core Team, 2022) to determine statistically 
significant breakpoints in the linear distances of the CIBW data using 
this regression method (see Section 6.5.5.3 of the POA's application 
for more details regarding this statistical analysis). This analysis 
identified breakpoints in the CPOA locations at 74, 1,651, 2,808, and 
7,369 m (Figure 2).

[[Page 76611]]

[GRAPHIC] [TIFF OMITTED] TN06NO23.055

    Piecewise regression is a common tool for modeling ecological 
thresholds (Lopez et al., 2020; Whitehead et al., 2016; Atwood et al., 
2016). In a similar scenario to the one outlined above, Mayette et al. 
(2022) used piecewise regression methods to model the distances between 
two individual CIBWs in a group in a nearshore and a far shore 
environment. For the POA's analysis, the breakpoints (i.e., 74, 1,651, 
2,808, and 7,369 m) detect a change in the frequency of CIBW groups 
sighted and the slope of the line between two points indicates the 
magnitude of change. A greater positive slope indicates a greater 
accumulation of sightings over the linear distance (x-axis) between the 
defining breakpoints, whereas a more level slope (i.e., closer to zero) 
indicates a lower accumulation of sightings over that linear distance 
(x-axis) between those defining breakpoints (Figure 2; see Table 6-8 in 
the POA's application for the slope estimates for the empirical 
cumulative distribution function).
    The breakpoints identified by the piecewise regression analysis are 
in agreement with what is known about CIBW behavior in Knik Arm based 
on recent monitoring efforts (61N Environmental, 2021, 2022a, 2022b; 
Easley-Appleyard and Leonard, 2022). Observation location data 
collected during POA monitoring programs indicate that CIBWs were 
consistently found in higher numbers in the nearshore areas, along both 
shorelines, and were found in lower numbers in the center of the Arm. 
Tracklines of CIBW group movements collected from 2020 to 2022 show 
that CIBWs displayed a variety of movement patterns that included 
swimming close to shore past the POA on the east side of Knik Arm 
(defined by breakpoint 1 at 74 m), with fewer CIBWs swimming in the 
center of Knik Arm (breakpoints 1 to 2, at 74 to 1,651 m). CIBWs 
commonly swam past the POA close to shore on the west side of Knik Arm, 
with no CIBWs able to swim farther from the POA in that area than the 
far shore (breakpoints 2 to 3, at 1,651 to 2,808 m). Behaviors and 
locations beyond breakpoint 4 (7,369 m) include swimming past the mouth 
of Knik Arm between the Susitna River area and Turnagain Arm; milling 
at the mouth of Knik Arm but not entering the Arm; and milling to the 
northwest of the POA without exiting Knik Arm. The shallowness of slope 
5, at distances greater than 7,369 m, could be due to detection falloff 
from a proximity (distance) bias, which would occur when PSOs are less 
likely to detect CIBW groups that are farther away than groups that are 
closer.
    The POA, in collaboration with NMFS, used the distances detected by 
the breakpoint analysis to define five sighting rate distance bins for 
CIBWs in the NES1 project area. Each breakpoint (74, 1,651, 2,808, and 
7,369 m, and the complete data set of observations [>7,369 m]) was 
rounded up to the nearest meter and considered the outermost limit of 
each sighting rate bin, resulting in five identified bins (table 11). 
All CIBW observations less than each bin's breakpoint distance were 
used to calculated that bin's respective monthly sighting rates (e.g., 
all sightings from 0 to 74 m are included in the sighting rates 
calculated for bin number 1, all sightings from 0 to 1,651 m are 
included in the sighting rates calculated for bin number 2, and so on). 
NES1 demolition is anticipated to take place from April through 
November 2024, therefore monthly sighting rates were only derived for 
these months (table 11).

[[Page 76612]]



                                      Table 11--CIBW Monthly Sighting Rates for Different Spatially-Based Bin Sizes
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                               CIBW/hour \1\
              Bin No.                  Distance  -------------------------------------------------------------------------------------------------------
                                         (m)         April         May          June         July        August     September     October      November
--------------------------------------------------------------------------------------------------------------------------------------------------------
1..................................        <= 74         0.09         0.06         0.10         0.04         0.83         0.62         0.51         0.11
2..................................     <= 1,651         0.25         0.14         0.13         0.06         1.43         1.30         1.15         0.70
3..................................     <= 2,808         0.36         0.22         0.21         0.07         2.08         1.90         2.04         0.73
4..................................     <= 7,369         0.67         0.33         0.29         0.13         2.25         2.19         2.42         0.73
5..................................      > 7,369         0.71         0.39         0.30         0.13         2.29         2.23         2.56         0.73
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Observation hours have been totaled from the PCT 2020 and 2021 programs, the NMFS 2021 data collection effort, and the SFD 2022 program (61N
  Environmental 2021, 2022a, 2022b; Easley-Appleyard and Leonard, 2022).

    Potential exposures (equated with takes) of CIBWs were calculated 
by multiplying the total number of vibratory installation or removal 
hours per month for each sized/shaped pile based on the anticipated 
construction schedule (table 2) with the corresponding sighting rate 
month and sighting rate distance bin (table 12). For example, the Level 
B harassment isopleth distance for the vibratory installation of 24-
inch (61-cm) piles is 2,247 m, which falls within bin number 3 (table 
11). Therefore, take for this activity is calculated by multiplying the 
total number of hours estimated each month to install 24-inch piles via 
a vibratory hammer by the monthly CIBW sighting rates calculated for 
bin number 3 (table 12). The resulting estimated CIBW exposures were 
totaled for all activities in each month (table 13).
    In their calculation of CIBW take, the POA assumed that only 24-
inch (61-cm) template piles would be installed (rather than 36-inch, 
91-cm) and removed during the project due to the vibratory removal of 
24-inch piles having the largest isopleth. If 36-inch (61-cm) piles are 
used for temporary stability template piles, it would be assumed that 
the potential impacts of this alternate construction scenario and 
method on marine mammals are fungible (i.e., that potential impacts of 
installation and removal of 36-inch (91-cm) steel pipe piles would be 
similar to the potential impacts of installation and removal of 24-inch 
(61-cm) steel pipe piles). Using the monthly activity estimates in 
hours (Table 2) and monthly calculated sighting rates (CIBWs/hour) for 
the spatially derived distance bins (table 12), the POA estimates that 
there could be up to 122 (121.1 rounded up to 122) instances of CIBW 
take where during the NES1 project (table 13).

                    Table 12--Allocation of Each Level B Harassment Isopleth to a Sighting Rate Bin and CIBW Monthly Sighting Rates for Different Pile Sizes and Hammer Types
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Level B                                                               CIBWs/hour
                                                                 harassment    Sighting  -------------------------------------------------------------------------------------------------------
                                                                  isopleth     rate bin
                                                                  distance    number and     April         May          June         July        August     September     October      November
                                                                    (m)        distance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch Vibratory Installation................................        2,247            3         0.36         0.22         0.21         0.07         2.08         1.90         2.04         0.73
                                                                               (2,808 m)
24-inch Vibratory Removal.....................................        5,968            4         0.67         0.33         0.29         0.13         2.25         2.19         2.42         0.73
                                                                               (7,369 m)
36-inch Vibratory Installation................................        4,514            4         0.67         0.33         0.29         0.13         2.25         2.19         2.42         0.73
                                                                               (7,369 m)
36-inch Vibratory Removal.....................................        1,700            3         0.36         0.22         0.21         0.07         2.08         1.90         2.04         0.73
                                                                               (2,808 m)
Sheet Pile Vibratory Removal..................................        1,954            3         0.36         0.22         0.21         0.07         2.08         1.90         2.04         0.73
                                                                               (2,808 m)
                                                               ---------------------------------------------------------------------------------------------------------------------------------
    Observation Hours/Month \1\:..............................  ...........  ...........         87.9        615.1        571.6        246.9        224.5        326.2        109.5        132.0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Observation hours have been totaled from the PCT 2020 and 2021 programs, the NMFS 2021 data collection effort, and the SFD 2022 program (61N Environmental, 2021, 2022a, 2022b; Easley-
  Appleyard and Leonard, 2022).

    For the PCT (85 FR 19294, April 6, 2020) and SFD (86 FR 50057, 
September 7, 2021) projects, NMFS accounted for the implementation of 
mitigation measures (e.g., shutdown procedures implemented when CIBWs 
entered or approached the estimated Level B harassment zone) by 
applying an adjustment factor to CIBW take estimates. This was based on 
the assumption that some Level B harassment takes would likely be 
avoided based on required shutdowns for CIBWs at the Level B harassment 
zones (see the Proposed Mitigation section for more information). For 
the PCT project, NMFS compared the number of realized takes at the POA 
to the number of authorized takes for previous projects from 2008 to 
2017 and found the percentage of realized takes ranged from 12 to 59 
percent with an average of 36 percent (85 FR 19294, April 6, 2020). 
NMFS then applied the highest percentage of previous realized takes (59 
percent during the 2009-2010 season) to ensure potential takes of CIBWs 
were fully evaluated. In doing so, NMFS assumed that approximately 59 
percent of the takes calculated would be realized during PCT and SFD 
construction (85 FR 19294, April 6, 2020; 86 FR 50057, September 7, 
2021) and that 41 percent of the calculated CIBW Level B harassment 
takes would be avoided by successful

[[Page 76613]]

implementation of required mitigation measures.
    The POA calculated the adjustment for successful implementation of 
mitigation measures for NES1 using the percentage of realized takes for 
the PCT project (see Table 6-12 in the POA's application). The recent 
data from PCT Phase 1 and PCT Phase 2 most accurately reflect the 
current marine mammal monitoring program, the current program's 
effectiveness, and CIBW occurrence in the proposed project area. 
Between the two phases of the PCT project, 90 total Level B harassment 
takes were authorized and 53 were potentially realized (i.e., number of 
CIBWs observed within estimated Level B harassment zones), equating to 
an overall percentage of 59 percent. The SFD Project, during which only 
7 percent of authorized take was potentially realized, represents 
installation of only 12 piles during a limited time period and does not 
represent the much higher number of piles and longer construction 
season anticipated for NES1.2
    NMFS proposes that the 59-percent adjustment accurately accounts 
for the efficacy of the POA's marine mammal monitoring program and 
required shutdown protocols. NMFS therefore assumes that approximately 
59 percent of the takes calculated for NES1 may actually be realized. 
This adjusts the potential takes by Level B harassment of CIBWs 
proposed for authorization from 122 to 72 (table 13). Take by Level A 
harassment is not anticipated or proposed to be authorized because the 
POA will be required to shutdown activities when CIBWs approach and or 
enter the Level B harassment zone (see the Proposed Mitigation section 
for more information).

                                              Table 13--Potential Monthly CIBW Level B Harassment Exposures
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                        April         May          June         July        August     September     October      November      Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch Vibratory Installation and           2.5          3.0          1.7          0.6         12.5          6.9          3.9          0.2         31.3
 Removal...........................
Sheet Pile Removal.................          3.6          9.9         12.5          4.4         27.0         22.8          8.1          1.5         89.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Total Estimated Level B Harassment Exposures for All Activities (Rounded):                                        121.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                             Total Estimated Level B Harassment Exposures with 59% Correction Factor (Rounded):                                71.5 (72)
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In summary, the total amount of Level A harassment and Level B 
harassment proposed to be authorized for each marine mammal stock is 
presented in table 14.

       Table 14--Amount of Proposed Take as a Percentage of Stock Abundance, by Stock and Harassment Type
----------------------------------------------------------------------------------------------------------------
                                                 Proposed take
            Species            ------------------------------------------------       Stock         Percent of
                                    Level A         Level B          Total                             stock
----------------------------------------------------------------------------------------------------------------
Gray whale....................               0               6               6  Eastern North           \1\ 0.02
                                                                                 Pacific.
Humpback whale................               0               4               4  Hawai[revaps]i..        \1\ 0.04
                                                                                Mexico-North             \2\ UNK
                                                                                 Pacific.
Beluga whale..................               0              72              72  Cook Inlet......           21.75
Killer whale..................               0               6               6  Eastern North           \1\ 0.31
                                                                                 Pacific Alaska
                                                                                 Resident.
                                                                                Eastern North            1.02\1\
                                                                                 Pacific Gulf of
                                                                                 Alaska,
                                                                                 Aleutian
                                                                                 Islands and
                                                                                 Bering Sea
                                                                                 Transient.
Harbor porpoise...............               1              17              18  Gulf of Alaska..            0.06
Steller sea lion..............               0               9               9  Western.........            0.02
Harbor seals..................              13             234             247  Cook Inlet/                 0.87
                                                                                 Shelikof Strait.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS conservatively assumes that all takes occur to each stock.
\2\ NMFS does not have an official abundance estimate for this stock and the minimum population estimate is
  considered to be unknown (Young et al., 2023).

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks, and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned), and;
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, and impact on 
operations.

[[Page 76614]]

    The POA presented mitigation measures in Section 11 of their 
application that were modeled after the requirements included in the 
IHAs issued for Phase 1 and Phase 2 PCT construction (85 FR 19294, 
April 6, 2020) and for SFD construction (86 FR 50057, September 7, 
2021), which were designed to minimize the total number, intensity, and 
duration of harassment events for CIBWs and other marine mammal species 
during those projects (61N Environmental, 2021, 2022a, 2022b). NMFS 
concurs that these proposed measures reduce the potential for CIBWs, 
and other marine mammals, to be adversely impacted by the proposed 
activity.
    The POA must employ the following mitigation measures:
     Ensure that construction supervisors and crews, the 
monitoring team and relevant POA staff are trained prior to the start 
of all pile driving, 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;
     Employ PSOs and establish monitoring locations as 
described in Section 5 of the IHA and the POA's Marine Mammal 
Monitoring and Mitigation Plan (see Appendix B of the POA's 
application). The POA must monitor the project area to the maximum 
extent possible based on the required number of PSOs, required 
monitoring locations, and environmental conditions;
     Monitoring must take place from 30 minutes prior to 
initiation of pile driving (i.e., pre-clearance monitoring) through 30 
minutes post-completion of pile driving;
     Pre-start clearance monitoring must be conducted during 
periods of visibility sufficient for the lead PSO to determine that the 
shutdown zones indicated in table 15 are clear of marine mammals. Pile 
driving may commence following 30 minutes of observation when the 
determination is made that the shutdown zones are clear of marine 
mammals or when the mitigation measures proposed specifically for CIBWs 
(below) are satisfied;
     For all construction activities, shutdown zones must be 
established following table 15. The purpose of a shutdown zone is 
generally to define an area within which shutdown of activity would 
occur upon sighting of a marine mammal (or in anticipation of an animal 
entering the defined area). In addition to the shutdown zones specified 
in table 15 and the minimum shutdown zone of 10-m described above, 
requirements included in NMFS' proposed IHA, the POA plans to implement 
a minimum 100-m shutdown zone around the active NES1 project work site, 
including around activities other than pile installation or removal 
that NMFS has determined do not present a reasonable potential to cause 
take of marine mammals. Shutdown zones for pile installation and 
removal would vary based on the type of construction activity and by 
marine mammal hearing group (table 15). Here, shutdown zones are larger 
than or equal to the calculated Level A harassment isopleths shown in 
table 9 for species other than CIBW and are equal to the estimated 
Level B harassment isopleths for CIBWs;

                                               Table 15--Proposed Shutdown Zones During Project Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 Shutdown zone (m)
                                                         ----------------------------------------------------------------
             Activity                  Pile type/size                       Non-CIBW MF                                         PW              OW
                                                           LF cetaceans      cetaceans         CIBWs       HF cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Removal....................  Sheet pile..........             160              10             900             190              90              10
Vibratory Installation............  24-inch (61-cm).....              20              10           2,300              20              10              10
                                    36-inch (91-cm).....              30              10           4,600              40              20              10
Vibratory Removal.................  Sheet pile..........              10              10           2,000              20              10              10
                                    24-inch (61-cm).....              40              10           6,000              60              30              10
                                    36-inch (91-cm).....              20              10           1,700              20              10              10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: cm = centimeter(s), m = meter(s).

     Marine mammals observed anywhere within visual range of 
the PSO must be tracked relative to construction activities. If a 
marine mammal is observed entering or within the shutdown zones 
indicated in table 15, pile driving must be delayed or halted. If pile 
driving is delayed or halted due to the presence of a marine mammal, 
the activity may not commence or resume until either the animal has 
voluntarily exited and been visually confirmed beyond the shutdown zone 
(table 15, or 15 minutes (non-CIBWs) or 30 minutes (CIBWs) have passed 
without re-detection of the animal;
     The POA 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. PSOs shall begin observing for marine mammals 30 
minutes before ``soft start'' or in-water pile installation or removal 
begins;
     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; and
     The POA must avoid direct physical interaction with marine 
mammals during construction activities. If a marine mammal comes within 
10 m of such activity, operations shall cease. Should a marine mammal 
come within 10 m of a vessel in transit, the boat operator will reduce 
vessel speed to the minimum level required to maintain steerage and 
safe working conditions. If human safety is at risk, the in-water 
activity will be allowed to continue until it is safe to stop.
    The following additional mitigation measures are proposed by NMFS 
for CIBWs:
     The POA must make all practicable efforts to complete 
construction activities between April and July, when CIBWs are 
typically found in lower numbers near the proposed site;
     Prior to the onset of pile driving, should a CIBW be 
observed approaching the estimated Level B harassment zone (Table 9) 
(i.e. the CIBWs shutdown zone column in Table 15), pile driving must 
not commence until the whale(s) moves

[[Page 76615]]

at least 100 m past the estimated Level B harassment zone and on a path 
away from the zone, or the whale has not been re-sighted within 30 
minutes;
     If pile installation or removal has commenced, and a 
CIBW(s) is observed within or likely to enter the estimated Level B 
harassment zone, pile installation or removal must shut down and not 
re-commence until the whale has traveled at least 100 m beyond the 
Level B harassment zone and is on a path away from such zone or until 
no CIBW has been observed in the Level B harassment zone for 30 
minutes; and
     If during installation and removal of piles, PSOs can no 
longer effectively monitor the entirety of the CIBW Level B harassment 
zone due to environmental conditions (e.g., fog, rain, wind), pile 
driving may continue only until the current segment of the pile is 
driven; no additional sections of pile or additional piles may be 
driven until conditions improve such that the Level B harassment zone 
can be effectively monitored. If the Level B harassment zone cannot be 
monitored for more than 15 minutes, the entire Level B harassment zone 
will be cleared again for 30 minutes prior to pile driving.
    In addition to these additional mitigation measures being proposed 
by NMFS, NMFS requested that the POA restrict all pile driving and 
removal work to April to July, when CIBWs are typically found in lower 
numbers. However, given the safety and environmental concerns of 
collapse of the Northern Extension once removal work commences, 
required sequencing of pile installation and removal and fill removal, 
and uncertainties and adaptive nature of the work, the POA stated that 
it cannot commit to restricting pile driving and removal to April to 
July. Instead, as required in the proposed mitigation, NMFS would 
require the POA to complete as much work as is practicable in April to 
July to reduce the amount of pile driving and removal activities in 
August through November.
    For previous IHAs issued to the POA (PCT: 85 FR 19294, April 6, 
2020; SFD: 86 FR 50057, September 7, 2021), the use of a bubble curtain 
to reduce noise has been required as a mitigation measure for certain 
pile driving scenarios. The POA did not propose to use a bubble curtain 
system during the NES1 project, stating that it is not a practicable 
mitigation measure for this demolition project. NMFS concurs with this 
determination. Practicability concerns include the following:
     NES1 construction activities includes installation of 
round, temporary, stability template piles to shore up the filled NES1 
structure while fill material and sheet piles are removed. Stability 
template piles that would be required for demolition of the sheet pile 
structure are located in proximity of the sheet piles. A bubble curtain 
would not physically fit between the sheet piles and the template 
piles;
     Bubble curtains could not be installed around the sheet 
piles as they are removed because the structure consists of sheet piles 
that are connected to one another and used to support fill-material. It 
would not be possible to place a bubble curtain system along the sheet 
pile face for similar reasons, including lack of space for the bubble 
curtain and the structures and equipment that would be needed to 
install and operate it, and the high likelihood that it could not 
function or be retrieved; and
     NES1 is a failed structure, and has been deemed ``globally 
unstable'' and poses significant risk for continued deterioration and 
structural collapse. If the existing structure were to collapse during 
deconstruction and sheet pile removal, there is risk of a significant 
release of impounded fill material into CIBW habitat, the POA's vessel 
operating and mooring areas, and the USACE Anchorage Harbor Project. 
Due to the stability risk of the existing impounded material, it is 
expected that construction and demolition means and methods would be 
highly adaptive once actual field work commences, and use of a bubble 
curtain with deconstruction would limit operations in the field and 
create significant health and safety issues.
    The POA also has efficacy concerns about requiring a bubble curtain 
for NES1 construction activities. Adding a requirement for a bubble 
curtain may hinder production, due to the time required to install and 
remove the bubble curtain itself. This has the potential to drive the 
in-water construction schedule further into the late summer months, 
which are known for higher CIBW abundance in lower Knik Arm, thus 
lengthening the duration of potential interactions between CIBW and in-
water works. Therefore, NMFS is concerned that use of a bubble curtain 
may not be an effective measure, given the potential that bubble 
curtain use could ultimately result in increased impacts to CIBW, in 
addition to the aforementioned practicability issues.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means of 
effecting the least practicable impact on the affected species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and,
     Mitigation and monitoring effectiveness.
    The POA would implement a marine mammal monitoring and mitigation 
strategy intended to avoid and minimize

[[Page 76616]]

impacts to marine mammals (see Appendix B of the POA's application for 
their Marine Mammal Monitoring and Mitigation Plan). Marine mammal 
monitoring would be conducted at all times when in-water pile 
installation and removal is taking place. Additionally, PSOs would be 
on-site monitoring for marine mammals during in-water cutting of sheet 
piles with shears or an ultrathermic torch.
    The marine mammal monitoring and mitigation program that is planned 
for NES1 construction would be modeled after the stipulations outlined 
in the IHAs for Phase 1 and Phase 2 PCT construction (85 FR 19294, 
April 6, 2020) and the IHA for SFD construction (86 FR 50057, September 
7, 2021).

Visual Monitoring

    Monitoring must be conducted by qualified, NMFS-approved PSOs, in 
accordance with the following:
     PSOs must be independent of the activity contractor (e.g., 
employed by a subcontractor) and have no other assigned tasks during 
monitoring periods. At least one PSO must have prior experience 
performing the duties of a PSO during construction activity pursuant to 
a NMFS-issued IHA or Letter of Concurrence. Other PSOs may substitute 
other relevant experience, education (degree in biological science or 
related field), or training for prior experience performing the duties 
of a PSO. PSOs must be approved by NMFS prior to beginning any activity 
subject to this IHA;
     The POA must employ PSO stations at a minimum of two 
locations from which PSOs can effectively monitor the shutdown zones 
(Table 15). Concerns about the stability of the NES1 project area 
preclude determination of the exact number and locations of PSO 
stations until the Construction Contractor develops their Construction 
Work Plan. PSO stations must be positioned at the best practical 
vantage points that are determined to be safe. Likely locations include 
the Anchorage Public Boat Dock at Ship Creek to the south of the 
proposed project site, and a location to the north of the project site, 
such as the northern end of POA property near Cairn Point (see North 
Extension area on Figure 12-1 in the POA's application) or at Port 
MacKenzie across Knik Arm (see Figure 12-1 in the POA's application for 
potential locations of PSO stations). A location near the construction 
activity may not be possible given the risk of structural collapse as 
outlined in the POA's IHA application. Placing a PSO on the 
northernmost portion of Terminal 3 would also be considered if deemed 
safe. Areas near Cairn Point or Port MacKenzie have safety, security, 
and logistical issues, which would need to be considered. Cairn Point 
proper is located on military land and has bear presence, and 
restricted access does not allow for the location of an observation 
station at this site. Tidelands along Cairn Point are accessible only 
during low tide conditions and have inherent safety concerns of being 
trapped by rising tides. Port MacKenzie is a secure port that is 
relatively remote, creating safety, logistical, and physical staffing 
limitations due to lack of nearby lodging and other facilities. The 
roadway travel time between port sites is approximately 2-3 hours. An 
adaptive management measure is proposed for a monitoring location north 
of the proposed project site, once the Construction Contractor has been 
selected and more detailed discussions can occur. Temporary staffing of 
a northerly monitoring station during peak marine mammal presence time 
periods and/or when shutdown zones are large would be considered. At 
least one PSO station must be able to fully observe the shutdown zones 
(Table 15);
     PSOs stations must be elevated platforms constructed on 
top of shipping containers or a similar base that is at least 8' 6'' 
high (i.e., the standard height of a shipping container) that can 
support up to three PSOs and their equipment. The platforms must be 
stable enough to support use of a theodolite and must be located to 
optimize the PSO's ability to observe marine mammals and the harassment 
zones;
     Each PSO station must have at least two PSOs on watch at 
any given time; one PSO must be observing, one PSO would be recording 
data (and observing when there are no data to record). Teams of three 
PSOs would include one PSO who would be observing, one PSO who would be 
recording data (and observing when there are no data to record), and 
one PSO who would be resting. In addition, if POA is conducting non-
NES1-related in-water work that includes PSOs, the NES1 PSOs must be in 
real-time contact with those PSOs, and both sets of PSOs must share all 
information regarding marine mammal sightings with each other;
     A designated lead PSO must always be on site. The lead 
observer must have prior experience performing the duties of a PSO 
during in-water construction activities pursuant to a NMFS-issued 
incidental take authorization or Letter of Concurrence. Each PSO 
station must also have a designated lead PSO specific to that station 
and shift. These lead PSOs must have prior experience working as a PSO 
during in-water construction activities;
     PSOs would use a combination of equipment to perform 
marine mammal observations and to verify the required monitoring 
distance from the project site, including 7 by 50 binoculars, 20x/40x 
tripod mounted binoculars, 25 by 150 ``big eye'' tripod mounted 
binoculars, and theodolites;
     PSOs must record all observations of marine mammals, 
regardless of distance from the pile being driven. PSOs shall document 
any behavioral reactions in concert with distance from piles being 
driven or removed;
    PSOs must have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to record required information 
including but not limited to the number and species of marine mammals 
observed; dates and times when in-water construction activities were 
conducted; dates, times, and reason for implementation of mitigation 
(or why mitigation was not implemented when required); and marine 
mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.

Reporting

    NMFS would require the POA to submit interim weekly and monthly 
monitoring reports (that include raw electronic data sheets) during the 
NES1 construction season. These reports must include a summary of 
marine mammal species and behavioral observations, construction 
shutdowns or delays, and construction work completed. They also must 
include an assessment of the amount of construction remaining to be 
completed (i.e., the number of estimated hours of work remaining), in 
addition to the number of CIBWs observed within estimated harassment 
zones to date.
    A draft summary marine mammal monitoring report must be submitted 
to NMFS within 90 days after the completion of all construction 
activities, or 60 days prior to a requested date of issuance of any 
future incidental take authorization for projects at the same location, 
whichever comes first. The

[[Page 76617]]

report would include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report must include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact or vibratory, the total 
equipment duration for vibratory installation and removal, and the 
total number of strikes for each pile during impact driving;
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: name of PSO who sighted the animal(s) and PSO location and 
activity at time of sighting; time of sighting; identification of the 
animal(s) (e.g., genus/species, lowest possible taxonomic level, or 
unidentified), PSO confidence in identification, and the composition of 
the group if there is a mix of species; distance and bearing of each 
marine mammal observed relative to the pile being driven for each 
sighting (if pile driving was occurring at time of sighting); estimated 
number of animals (minimum, maximum, and best estimate); estimated 
number of animals by cohort (adults, juveniles, neonates, group 
composition, sex class, etc.); animal's closest point of approach and 
estimated time spent within the harassment zone; group spread and 
formation (for CIBWs only); description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses that may have resulted 
from the activity (e.g., no response or changes in behavioral state 
such as ceasing feeding, changing direction, flushing, or breaching);
     Number of marine mammals detected within the harassment 
zones and shutdown zones, by species;
     Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensued, and resulting changes in behavior of the 
animal(s), if any;
    If no comments are received from NMFS within 30 days, the draft 
final report would constitute the final report. If comments are 
received, a final report addressing NMFS comments must be submitted 
within 30 days after receipt of comments.

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the IHA-holder must 
immediately cease the specified activities and report the incident to 
the Office of Protected Resources, NMFS 
([email protected]), and to the Alaska Regional 
Stranding Coordinator as soon as feasible. If the death or injury was 
clearly caused by the specified activity, the POA must immediately 
cease the specified activities until NMFS is able to review the 
circumstances of the incident and determine what, if any, additional 
measures are appropriate to ensure compliance with the terms of the 
IHA. The POA must not resume their activities until notified by NMFS. 
The report must include the following information:
     Time, date, and location (latitude and longitude) of the 
first discovery (and updated location information if known and 
applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, this introductory discussion of our analysis 
applies to all the species listed in Table 14, except CIBWs, given that 
many of the anticipated effects of this project on different marine 
mammal stocks are expected to be relatively similar in nature. For 
CIBWs, there are meaningful differences in anticipated individual 
responses to activities, impact of expected take on the population, or 
impacts on habitat; therefore, we provide a separate detailed analysis 
for CIBWs following the analysis for other species for which we propose 
take authorization.
    NMFS has identified key factors which may be employed to assess the 
level of analysis necessary to conclude whether potential impacts 
associated with a specified activity should be considered negligible. 
These include (but are not limited to) the type and magnitude of 
taking, the amount and importance of the available habitat for the 
species or stock that is affected, the duration of the anticipated 
effect to the species or stock, and the status of the species or stock. 
The potential effects of the specified actions on gray whales, humpback 
whales, killer whales, harbor porpoises, Steller sea lions, and harbor 
seals are discussed below. Some of these factors also apply to CIBWs; 
however, a more detailed analysis for CIBWs is provided in a separate 
sub-section below.
    Pile driving associated with the project, as outlined previously, 
has the potential to disturb or displace marine mammals. Specifically, 
the specified activities may result in take, in the form of Level B 
harassment and, for some species, Level A harassment, from underwater 
sounds generated by pile driving. Potential takes could occur if marine 
mammals are present in zones

[[Page 76618]]

ensonified above the thresholds for Level B harassment or Level A 
harassment, identified above, while activities are underway.
    The POA's proposed activities and associated impacts would occur 
within a limited, confined area of the stocks' range. The work would 
occur in the vicinity of the NES1 site and sound from the proposed 
activities would be blocked by the coastline along Knik Arm along the 
eastern boundaries of the site, and for those harassment isopleths that 
extend more than 3,000 m (i.e., the vibratory installation of 36-inch 
(91-cm) piles and vibratory removal of 24-inch (61-inch) piles), 
directly across the Arm along the western shoreline (see Figure 6-4 in 
the POA's application)). The intensity and duration of take by Level A 
and Level B harassment would be minimized through use of mitigation 
measures described herein. Further the amount of take proposed to be 
authorized is small when compared to stock abundance (see Table 14). In 
addition, NMFS does not anticipate that serious injury or mortality 
will occur as a result of the POA's planned activity given the nature 
of the activity, even in the absence of required mitigation.
    Exposures to elevated sound levels produced during pile driving may 
cause behavioral disturbance of some individuals. Behavioral responses 
of marine mammals to pile driving at the proposed project site are 
expected to be mild, short term, and temporary. Effects on individuals 
that are taken by Level B harassment, as enumerated in the Estimated 
Take section, on the basis of reports in the literature as well as 
monitoring from other similar activities at the POA and elsewhere, will 
likely be limited to reactions such as increased swimming speeds, 
increased surfacing time, or decreased foraging (if such activity were 
occurring; e.g., Ridgway et al., 1997; Nowacek et al., 2007; Thorson 
and Reyff, 2006; Kendall and Cornick, 2015; Goldbogen et al., 2013b; 
Piwetz et al., 2021). Marine mammals within the Level B harassment 
zones may not show any visual cues they are disturbed by activities or 
they could become alert, avoid the area, leave the area, or display 
other mild responses that are not observable such as changes in 
vocalization patterns or increased haul out time (e.g., Tougaard et 
al., 2003; Carstensen et al., 2006; Thorson and Reyff, 2006; Parks et 
al., 2007; Brandt et al., 2011; Graham et al., 2017). However, as 
described in the Potential Effects of Specified Activities on Marine 
Mammals and Their Habitat section of this notice, marine mammals, 
excepting CIBWs, observed within Level A and Level B harassment zones 
related to recent POA construction activities have not shown any acute 
observable reactions to pile driving activities that have occurred 
during the PCT and SFD projects (61N Environmental, 2021, 2022a, 
2022b).
    Some of the species present in the region will only be present 
temporarily based on seasonal patterns or during transit between other 
habitats. These temporarily present species will be exposed to even 
smaller periods of noise-generating activity, further decreasing the 
impacts. Most likely, individual animals will simply move away from the 
sound source and be temporarily displaced from the area. Takes may also 
occur during important feeding times. The project area though 
represents a small portion of available foraging habitat and impacts on 
marine mammal feeding for all species should be minimal.
    The activities analyzed here are similar to numerous other 
construction activities conducted in Alaska (e.g., 86 FR 43190, August 
6, 2021; 87 FR 15387, March 18, 2022), including the PCT and SFD 
projects within Upper Knik Arm (85 FR 19294, April 6, 2020; 86 FR 
50057, September 7, 2021, respectively) which have taken place with no 
known long-term adverse consequences from behavioral harassment. Any 
potential reactions and behavioral changes are expected to subside 
quickly when the exposures cease and, therefore, no such long-term 
adverse consequences should be expected (e.g., Graham et al., 2017). 
For example, harbor porpoises returned to a construction area between 
pile-driving events within several days during the construction of 
offshore wind turbines near Denmark (Carstensen et al., 2006). The 
intensity of Level B harassment events would be minimized through use 
of mitigation measures described herein, which were not quantitatively 
factored into the take estimates. The POA would use PSOs stationed 
strategically to increase detectability of marine mammals during in-
water construction activities, enabling a high rate of success in 
implementation of shutdowns to avoid or minimize injury for most 
species. Further, given the absence of any major rookeries and haulouts 
within the estimated harassment zones, we assume that potential takes 
by Level B harassment would have an inconsequential short-term effect 
on individuals and would not result in population-level impacts.
    As stated in the mitigation section, the POA will implement 
shutdown zones that equal or exceed the Level A harassment isopleths 
shown in Table 9. Take by Level A harassment is proposed for 
authorization for some species (harbor seals and harbor porpoises) to 
account for the potential that an animal could enter and remain within 
the Level A harassment zone for a duration long enough to incur PTS. 
Any take by Level A harassment is expected to arise from, at most, a 
small degree of PTS because animals would need to be exposed to higher 
levels and/or longer duration than are expected to occur here in order 
to incur any more than a small degree of PTS.
    Due to the levels and durations of likely exposure, animals that 
experience PTS will likely only receive slight PTS, i.e., minor 
degradation of hearing capabilities within regions of hearing that 
align most completely with the frequency range of the energy produced 
by POA's proposed in-water construction activities (i.e., the low-
frequency region below 2 kHz), not severe hearing impairment or 
impairment in the ranges of greatest hearing sensitivity. If hearing 
impairment does occur, it is most likely that the affected animal will 
lose a few dBs in its hearing sensitivity, which in most cases is not 
likely to meaningfully affect its ability to forage and communicate 
with conspecifics. There are no data to suggest that a single instance 
in which an animal accrues PTS (or TTS) and is subject to behavioral 
disturbance would result in impacts to reproduction or survival. If PTS 
were to occur, it would be at a lower level likely to accrue to a 
relatively small portion of the population by being a stationary 
activity in one particular location. Additionally, and as noted 
previously, some subset of the individuals that are behaviorally 
harassed could also simultaneously incur some small degree of TTS for a 
short duration of time. Because of the small degree anticipated, 
though, any PTS or TTS potentially incurred here is not expected to 
adversely impact individual fitness, let alone annual rates of 
recruitment or survival.
    Theoretically, repeated, sequential exposure to pile driving noise 
over a long duration could result in more severe impacts to individuals 
that could affect a population (via sustained or repeated disruption of 
important behaviors such as feeding, resting, traveling, and 
socializing; Southall et al., 2007). Alternatively, marine mammals 
exposed to repetitious construction sounds may become habituated, 
desensitized, or tolerant after initial exposure to these sounds 
(reviewed by Richardson et al., 1995; Southall et al., 2007). Given 
that marine mammals still frequent and use Knik Arm despite being 
exposed to pile

[[Page 76619]]

driving activities across many years, these severe population level of 
impacts are not anticipated. The absence of any pinniped haulouts or 
other known non-CIBW home-ranges in the proposed action area further 
decreases the likelihood of severe population level impacts.
    The NES1 project is also not expected to have significant adverse 
effects on any marine mammal habitat. The project activities would 
occur within the same footprint as existing marine infrastructure, and 
when construction is complete, subtidal and intertidal habitats 
previously lost at the project site would be restored. Impacts to the 
immediate substrate are anticipated, but these would be limited to 
minor, temporary suspension of sediments, which could impact water 
quality and visibility for a short amount of time but which would not 
be expected to have any effects on individual marine mammals. While the 
area is generally not high quality habitat, it is expected to be of 
higher quality to marine mammals and fish after NES1 construction is 
complete as the site returns to its natural state and is colonized by 
marine organisms. Further, there are no known BIAs near the project 
zone, except for CIBWs, that will be impacted by the POA's planned 
activities.
    Impacts to marine mammal prey species are also expected to be minor 
and temporary and to have, at most, short-term effects on foraging of 
individual marine mammals, and likely no effect on the populations of 
marine mammals as a whole. Overall, the area impacted by the NES1 
project is very small compared to the available surrounding habitat, 
and does not include habitat of particular importance. The most likely 
impact to prey would be temporary behavioral avoidance of the immediate 
area. During construction activities, it is expected that some fish and 
marine mammals would temporarily leave the area of disturbance, thus 
impacting marine mammals' foraging opportunities in a limited portion 
of their foraging range. But, because of the relatively small area of 
the habitat that may be affected, and lack of any habitat of particular 
importance, the impacts to marine mammal habitat are not expected to 
cause significant or long-term negative consequences. Further, as 
described above, additional habitat for marine mammal prey will be 
available after the completion of the proposed construction activities 
likely providing additional foraging, migrating, and rearing habitats 
to fish and foraging habitat to marine mammals.
    In summary and as described above, the following factors support 
our preliminary negligible impact determinations for the affected 
stocks of gray whales, humpback whales, killer whales, harbor 
porpoises, Steller sea lions, and harbor seals:
     No takes by mortality or serious injury are anticipated or 
authorized;
     Any acoustic impacts to marine mammal habitat from pile 
driving (including to prey sources as well as acoustic habitat, and 
including resulting behavioral impacts e.g., from masking) are expected 
to be temporary and minimal;
     Take would not occur in places and/or times where take 
would be more likely to accrue to impacts on reproduction or survival, 
such as within ESA-designated or proposed critical habitat, BIAs, or 
other habitats critical to recruitment or survival (e.g., rookery);
     The project area represents a very small portion of the 
available foraging area for all potentially impacted marine mammal 
species;
     Take will only occur within upper Cook Inlet--a limited, 
confined area of any given stock's home range;
     Monitoring reports from similar work in Knik Arm have 
documented little to no observable effect on individuals of the same 
species impacted by the specified activities;
     The required mitigation measures (i.e., soft starts, pre-
clearance monitoring, shutdown zones) are expected to be effective in 
reducing the effects of the specified activity by minimizing the 
numbers of marine mammals exposed to injurious levels of sound, and by 
ensuring that any take by Level A harassment is, at most, a small 
degree of PTS and of a lower degree that would not impact the fitness 
of any animals; and
     The intensity of anticipated takes by Level B harassment 
is low for all stocks consisting of, at worst, temporary modifications 
in behavior, and would not be of a duration or intensity expected to 
result in impacts on reproduction or survival.
    Cook Inlet Beluga Whales. For CIBWs, we further discuss our 
negligible impact findings in the context of potential impacts to this 
endangered stock based on our evaluation of the take proposed for 
authorization (Table 14).
    As described in the Recovery Plan for the CIBW (NMFS, 2016b), NMFS 
determined the following physical or biological features are essential 
to the conservation of this species: (1) Intertidal and subtidal waters 
of Cook Inlet with depths less than 9 m mean lower low water and within 
8 km of high and medium flow anadromous fish streams; (2) Primary prey 
species consisting of four species of Pacific salmon (Chinook, sockeye, 
chum, and coho), Pacific eulachon, Pacific cod, walleye pollock, 
saffron cod, and yellowfin sole, (3) Waters free of toxins or other 
agents of a type and amount harmful to CIBWs, (4) Unrestricted passage 
within or between the critical habitat areas, and (5) Waters with in-
water noise below levels resulting in the abandonment of critical 
habitat areas by CIBWs. The NES1 project will not impact essential 
features 1-3 listed above. All construction will be done in a manner 
implementing best management practices to preserve water quality, and 
no work will occur around creek mouths or river systems leading to prey 
abundance reductions. In addition, no physical structures will restrict 
passage; however, impacts to the acoustic habitat are relevant and 
discussed here.
    Monitoring data from the POA suggest pile driving does not 
discourage CIBWs from entering Knik Arm and traveling to critical 
foraging grounds such as those around Eagle Bay (e.g., 61N 
Environmental, 2021, 2022a, 2022b; Easley-Appleyard and Leonard, 2022). 
As described in the Potential Effects of Specified Activities on Marine 
Mammals and Their Habitat section of this notice, sighting rates were 
not different in the presence or absence of pile driving (Kendall and 
Cornick, 2015). In addition, large numbers of CIBWs have continued to 
use Knik Arm and pass through the area during pile driving projects 
that have taken place at the POA during the past two decades (Funk et 
al., 2005; Prevel-Ramos et al., 2006; Markowitz and McGuire, 2007; 
Cornick and Saxon-Kendall, 2008, 2009; ICRC, 2009, 2010, 2011, 2012; 
Cornick et al., 2010, 2011; Cornick and Pinney, 2011; Cornick and 
Seagars, 2016; POA, 2019), including during the recent PCT and SFD 
construction projects (61N Environmental, 2021, 2022a, 2022b; Easley-
Appleyard and Leonard, 2022). These findings are not surprising as food 
is a strong motivation for marine mammals. As described in Forney et 
al. (2017), animals typically favor particular areas because of their 
importance for survival (e.g., feeding or breeding), and leaving may 
have significant costs to fitness (reduced foraging success, increased 
predation risk, increased exposure to other anthropogenic threats). 
Consequently, animals may be highly motivated to maintain foraging 
behavior in historical foraging areas despite negative impacts (e.g., 
Rolland et al., 2012). Previous monitoring data indicates CIBWs are

[[Page 76620]]

responding to pile driving noise, but not through abandonment of 
critical habitat, including primary foraging areas north of the port. 
Instead, they travel more often and faster past the POA, more quietly, 
and in tighter groups (Kendall and Cornick, 2015; 61N Environmental, 
2021, 2022a, 2022b).
    During PCT and SFD construction monitoring, little variability was 
evident in the behaviors recorded from month to month, or between 
sightings that coincided with in-water pile installation and removal 
and those that did not (61N Environmental, 2021, 2022a, 2022b; Easley-
Appleyard and Leonard, 2022). Of the 386 CIBWs groups sighted during 
PCT and SFD construction monitoring, 10 groups were observed during or 
within minutes of in-water impact pile installation and 56 groups were 
observed during or within minutes of vibratory pile installation or 
removal (61N Environmental, 2021, 2022a, 2022b). In general, CIBWs were 
more likely to display no reaction or to continue to move towards the 
PCT or SFD during pile installation and removal. In the situations 
during which CIBWs showed a possible reaction (six groups during impact 
driving and 13 groups during vibratory driving), CIBWs were observed 
either moving away immediately after the pile driving activities 
started or were observed increasing their rate of travel.
    NMFS funded a visual marine mammal monitoring project in 2021 
(described in the Potential Effects of Specified Activities on Marine 
Mammals and Their Habitat) to supplement sighting data collected by the 
POA monitoring program during non-pile driving days in order to further 
evaluate the impacts of anthropogenic activities on CIBWs (Easley-
Appleyard and Leonard, 2022). Preliminary results suggest that group 
size ranged from 1 to 34 whales, with an average of 3 to 5.6, depending 
on the month. September had the highest sighting rate with 4.08 whales 
per hour, followed by October and August (3.46 and 3.41, respectively). 
Traveling was recorded as the primary behavior for 80 percent of the 
group sightings and milling was the secondary behavior most often 
recorded. Sighting duration varied from a single surfacing lasting less 
than 1 minute to 380 minutes. Preliminary findings suggest these 
results are consistent with the results from the POA's PCT and SFD 
monitoring efforts. For example, group sizes ranged from 2.38 to 4.32 
depending on the month and the highest sighting rate was observed in 
September (1.75). In addition, traveling was the predominant behavior 
observed for all months and categories of construction activity (i.e., 
no pile driving, before pile driving, during pile driving, between pile 
driving, or after pile driving), being recorded as the primary behavior 
for 86 percent of all sightings, and either the primary or secondary 
behavior for 95 percent of sightings.
    Easley-Appleyard and Leonard (2022) also asked PSOs to complete a 
questionnaire post-monitoring that provided NMFS with qualitative data 
regarding CIBW behavior during observations. Specifically during pile 
driving events, the PSOs noted that CIBW behaviors varied; however, 
multiple PSOs noted seeing behavioral changes specifically during 
impact pile driving (which would only be used when necessary to loosen 
piles for vibratory removal or direct pulling during the NES1 project) 
and not during vibratory pile driving. CIBWs were observed sometimes 
changing direction, turning around, or changing speed during impact 
pile driving. There were numerous instances where CIBWs were seen 
traveling directly towards the POA during vibratory pile driving before 
entering the Level B harassment zone (POA was required to shutdown 
prior to CIBWs entering the Level B harassment zone), which is 
consistent with findings during the POA's PCT and SFD monitoring 
efforts (61N Environmental, 2021, 2022a, 2022b). The PSOs also reported 
that it seemed more likely for CIBWs to show more cryptic behavior 
during pile driving (e.g., surfacing infrequently and without clear 
direction), though this seemed to vary across months (Easley-Appleyard 
and Leonard, 2022).
    We anticipate that disturbance to CIBWs will manifest in the same 
manner when they are exposed to noise during the NES1 project: whales 
would move quickly and silently through the area in more cohesive 
groups. We do not believe exposure to elevated noise levels during 
transit past the POA has adverse effects on reproduction or survival as 
the whales continue to access critical foraging grounds north of the 
POA, even if having shown a potential reaction during pile driving, and 
tight associations help to mitigate the potential for any contraction 
of communication space for a group. We also do not anticipate that 
CIBWs will abandon entering or exiting Knik Arm, as this is not evident 
based on previous years of monitoring data (e.g., Kendall and Cornick, 
2015; 61N Environmental, 2021, 2022a, 2022b; Easley-Appleyard and 
Leonard, 2022), and the pre-pile driving clearance mitigation measure 
is designed to further avoid any potential abandonment. Finally, as 
described previously, both telemetry (tagging) and acoustic data 
suggest CIBWs likely stay in upper Knik Arm (i.e., north of the NES1 
project site) for several days or weeks before exiting Knik Arm. 
Specifically, a CIBW instrumented with a satellite link time/depth 
recorder entered Knik Arm on August 18, 1999 and remained in Eagle Bay 
until September 12, 1999 (Ferrero et al., 2000). Further, a recent 
detailed re-analysis of the satellite telemetry data confirms how 
several tagged whales exhibited this same movement pattern: whales 
entered Knik Arm and remained there for several days before exiting 
through lower Knik Arm (Shelden et al., 2018). This longer-term use of 
upper Knik Arm will avoid repetitive exposures from pile driving noise.
    There is concern that exposure to pile driving at the POA could 
result in CIBWs avoiding Knik Arm and thereby not accessing the 
productive foraging grounds north of POA such as Eagle River flats 
thus, impacting essential feature number five above. Although the data 
previously presented demonstrate CIBWs are not abandoning the area 
(i.e., no significant difference in sighting rate with and without pile 
driving), results of an expert elicitation (EE) at a 2016 workshop, 
which predicted the impacts of noise on CIBW survival and reproduction 
given lost foraging opportunities, helped to inform our assessment of 
impacts on this stock. The 2016 EE workshop used conceptual models of 
an interim population consequences of disturbance (PCoD) for marine 
mammals (NRC, 2005; New et al., 2014; Tollit et al., 2016) to help in 
understanding how noise-related stressors might affect vital rates 
(survival, birth rate and growth) for CIBW (King et al., 2015). NMFS 
(2016b) suggests that the main direct effects of noise on CIBW are 
likely to be through masking of vocalizations used for communication 
and prey location and habitat degradation. The 2016 workshop on CIBWs 
was specifically designed to provide regulators with a tool to help 
understand whether chronic and acute anthropogenic noise from various 
sources and projects are likely to be limiting recovery of the CIBW 
population. The full report can be found at https://www.smruconsulting.com/publications/ with a summary of the expert 
elicitation portion of the workshop below.
    For each of the noise effect mechanisms chosen for EE, the experts 
provided a set of parameters and values that determined the forms of a 
relationship between the number of days of disturbance a female CIBW 
experiences in a particular period and the effect of that disturbance 
on her

[[Page 76621]]

energy reserves. Examples included the number of days of disturbance 
during the period April, May, and June that would be predicted to 
reduce the energy reserves of a pregnant CIBW to such a level that she 
is certain to terminate the pregnancy or abandon the calf soon after 
birth, the number of days of disturbance in the period April-September 
required to reduce the energy reserves of a lactating CIBW to a level 
where she is certain to abandon her calf, and the number of days of 
disturbance where a female fails to gain sufficient energy by the end 
of summer to maintain themselves and their calves during the subsequent 
winter. Overall, median values ranged from 16 to 69 days of disturbance 
depending on the question. However, for this elicitation, a ``day of 
disturbance'' was defined as any day on which an animal loses the 
ability to forage for at least one tidal cycle (i.e., it forgoes 50-100 
percent of its energy intake on that day). The day of disturbance 
considered in the context of the report is notably more severe than the 
Level B harassment expected to result from these activities, which as 
described is expected to be comprised predominantly of temporary 
modifications in the behavior of individual CIBWs (e.g., faster swim 
speeds, more cohesive group structure, decreased sighting durations, 
cessation of vocalizations). Also, NMFS proposes to authorize 72 
instances of takes, with the instances representing disturbance events 
within a day--this means that either 72 different individual CIBWs are 
disturbed on no more than 1 day each, or some lesser number of 
individuals may be disturbed on more than 1 day, but with the product 
of individuals and days not exceeding 72. Given the overall anticipated 
take, it is unlikely that any one CIBW will be disturbed on more than a 
few days. Further, the mitigation measures NMFS has prescribed for the 
NES1 project are designed to avoid the potential that any animal will 
lose the ability to forage for one or more tidal cycles should they be 
foraging in the proposed action area, which is not known to be a 
particularly important feeding area for CIBWs. While Level B harassment 
(behavioral disturbance) would be authorized, the POA's mitigation 
measures will limit the severity of the effects of that Level B 
harassment to behavioral changes such as increased swim speeds, tighter 
group formations, and cessation of vocalizations, not the loss of 
foraging capabilities. Regardless, this elicitation recognized that 
pregnant or lactating females and calves are inherently more at risk 
than other animals, such as males. NMFS has determined all CIBWs 
warrant pile driving shutdown to be protective of potential vulnerable 
life stages, such as pregnancy, that could not be determined from 
observations, and to avoid more severe behavioral reaction.
    POA proposed and NMFS has prescribed mitigation measures to 
minimize exposure to CIBWs, specifically, shutting down pile driving 
should a CIBW approach or enter the Level B harassment zone. These 
measures are designed to ensure CIBWs will not abandon critical habitat 
and exposure to pile driving noise will not result in adverse impacts 
on the reproduction or survival of any individuals. The location of the 
PSOs would allow for detection of CIBWs and behavioral observations 
prior to CIBWs entering the Level B harassment zone. Further, impact 
driving appeared to cause behavioral reactions more readily than 
vibratory hammering (61N Environmental, 2021, 2022a, 2022b), which 
would only be used in situations where sheet piles remain seized in the 
sediments and cannot be loosened or broken free with a vibratory 
hammer, which is expected to be uncommon during the NES1 project. If 
impact driving does occur, the POA must implement soft starts, which 
ideally allows animals to leave a disturbed area before the full-power 
driving commences (Tougaard et al., 2012). Although NMFS does not 
anticipate CIBWs will abandon entering Knik Arm in the presence of pile 
driving with the required mitigation measures, PSOs will be integral to 
identifying if CIBWs are potentially altering pathways they would 
otherwise take in the absence of pile driving. Finally, take by 
mortality, serious injury, or Level A harassment of CIBWs is not 
anticipated or proposed to be authorized.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the CIBWs through 
effects on annual rates of recruitment or survival:
     No mortality is anticipated or proposed to be authorized;
     The area of exposure would be limited to habitat primarily 
used as a travel corridor. Data demonstrates Level B harassment of 
CIBWs typically manifests as increased swim speeds past the POA, 
tighter group formations, and cessation of vocalizations, rather than 
through habitat abandonment;
     No critical foraging grounds (e.g., Eagle Bay, Eagle 
River, Susitna Delta) would be impacted by pile driving; and
     While animals could be harassed more than once, exposures 
are not likely to exceed more than a few per year for any given 
individual and are not expected to occur on sequential days; thereby 
decreasing the likelihood of physiological impacts caused by chronic 
stress or masking.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the required monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the specified activity will have a negligible impact 
on all affected marine mammal species or stocks.

Small Numbers

    As noted previously, only take of small numbers of marine mammals 
may be authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    For all stocks, except for the Mexico-North Pacific stock of 
humpback whales whose abundance estimate is unknown, the amount of 
taking is less than one-third of the best available population 
abundance estimate (in fact it is less than 2 percent for all stocks, 
except for CIBWs whose proposed take is 22 percent of the stock; Table 
14). The number of animals proposed for authorization to be taken from 
these stocks would be considered small relative to the relevant stock's 
abundances even if each estimated take occurred to a new individual. 
The amount of take authorized likely represents smaller numbers of 
individual harbor seals and Steller sea lions. Harbor seals tend to 
concentrate near Ship Creek and have small home ranges. It is possible 
that a single individual harbor seal may linger near the POA, 
especially near Ship Creek, and be counted multiple times each day as 
it moves around and resurfaces in

[[Page 76622]]

different locations. Previous Steller sea lion sightings identified 
that if a Steller sea lion is within Knik Arm, it is likely lingering 
to forage on salmon or eulachon runs and may be present for several 
days. Therefore, the amount of take authorized likely represents repeat 
exposures to the same animals. For all species, PSOs would count 
individuals as separate unless they cannot be individually identified.
    Abundance estimates for the Mexico-North Pacific stock of humpback 
whales are based upon data collected more than 8 years ago and, 
therefore, current estimates are considered unknown (Young et al., 
2023). The most recent minimum population estimates (NMIN) 
for this population include an estimate of 2,241 individuals between 
2003 and 2006 (Martinez-Aguilar, 2011) and 766 individuals between 2004 
and 2006 (Wade, 2021). NMFS' Guidelines for Assessing Marine Mammal 
Stocks suggest that the NMIN estimate of the stock should be 
adjusted to account for potential abundance changes that may have 
occurred since the last survey and provide reasonable assurance that 
the stock size is at least as large as the estimate (NMFS, 2023). The 
abundance trend for this stock is unclear; therefore, there is no basis 
for adjusting these estimates (Young et al., 2023). Assuming the 
population has been stable, the 4 takes of this stock proposed for 
authorization represents small numbers of this stock (0.18 percent of 
the stock assuming a NMIN of 2,241 individuals and 0.52 
percent of the stock assuming an NMIN of 766 individuals).
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would be taken relative to the population 
size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    In order to issue an IHA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50 
CFR 216.103 as an impact resulting from the specified activity: (1) 
That is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.
    While no significant subsistence activity currently occurs within 
or near the POA, Alaska Natives have traditionally harvested 
subsistence resources, including marine mammals, in upper Cook Inlet 
for millennia. CIBWs are more than a food source; they are important to 
the cultural and spiritual practices of Cook Inlet Native communities 
(NMFS, 2008b). Dena'ina Athabascans, currently living in the 
communities of Eklutna, Knik, Tyonek, and elsewhere, occupied 
settlements in Cook Inlet for the last 1,500 years and have been the 
primary traditional users of this area into the present.
    NMFS estimated that 65 CIBWs per year (range 21-123) were killed 
between 1994 and 1998, including those successfully harvested and those 
struck and lost. NMFS concluded that this number was high enough to 
account for the estimated 14 percent annual decline in population 
during this time (Hobbs et al., 2008); however, given the difficulty of 
estimating the number of whales struck and lost during the hunts, 
actual mortality may have been higher. During this same period, 
population abundance surveys indicated a population decline of 47 
percent, although the reason for this decline should not be associated 
solely with subsistence hunting and likely began well before 1994 (Rugh 
et al., 2000).
    In 1999, a moratorium was enacted (Pub. L. 106-31) prohibiting the 
subsistence harvest of CIBWs except through a cooperative agreement 
between NMFS and the affected Alaska Native organizations. NMFS began 
working cooperatively with the Cook Inlet Marine Mammal Council 
(CIMMC), a group of tribes that traditionally hunted CIBWs, to 
establish sustainable harvests. CIMMC voluntarily curtailed its 
harvests in 1999. In 2000, NMFS designated the Cook Inlet stock of 
beluga whales as depleted under the MMPA (65 FR 34590, May 31, 2000). 
NMFS and CIMMC signed Co-Management of the Cook Inlet Stock of Beluga 
Whales agreements in 2000, 2001, 2002, 2003, 2005, and 2006. CIBW 
harvests between 1999 and 2006 resulted in the strike and harvest of 
five whales, including one whale each in 2001, 2002, and 2003, and two 
whales in 2005 (NMFS, 2008b). No hunt occurred in 2004 due to higher-
than-normal mortality of CIBWs in 2003, and the Native Village of 
Tyonek agreed to not hunt in 2007. Since 2008, NMFS has examined how 
many CIBWs could be harvested during 5-year intervals based on 
estimates of population size and growth rate and determined that no 
harvests would occur between 2008 and 2012 and between 2013 and 2017 
(NMFS, 2008b). The CIMMC was disbanded by unanimous vote of the CIMMC 
member Tribes' representatives in June 2012, and a replacement group of 
Tribal members has not been formed to date. There has been no 
subsistence harvest of CIBWs since 2005 (NMFS, 2022d).
    Subsistence harvest of other marine mammals in upper Cook Inlet is 
limited to harbor seals. Steller sea lions are rare in upper Cook 
Inlet; therefore, subsistence use of this species is not common. 
However, Steller sea lions are taken for subsistence use in lower Cook 
Inlet. Residents of the Native Village of Tyonek are the primary 
subsistence users in the upper Cook Inlet area. While harbor seals are 
hunted for subsistence purposes, harvests of this for traditional and 
subsistence uses by Native peoples have been low in upper Cook Inlet 
(e.g., 33 harbor seals were harvested in Tyonek between 1983 and 2013; 
see Table 8-1 in the POA's application), although these data are not 
currently being collected and summarized. As the POA's proposed project 
activities will take place within the immediate vicinity of the POA, no 
activities will occur in or near Tyonek's identified traditional 
subsistence hunting areas. As the harvest of marine mammals in upper 
Cook Inlet is historically a small portion of the total subsistence 
harvest, and the number of marine mammals using upper Cook Inlet is 
proportionately small, the number of marine mammals harvested in upper 
Cook Inlet is expected to remain low.
    The potential impacts from harassment on stocks that are harvested 
in Cook Inlet would be limited to minor behavioral changes (e.g., 
increased swim speeds, changes in dive time, temporary avoidance near 
the POA, etc.) within the vicinity of the POA. Some PTS may occur; 
however, the shift is likely to be slight due to the implementation of 
mitigation measures (e.g., shutdown zones, pre-clearance monitoring, 
soft starts) and the shift would be limited to lower pile driving 
frequencies which are on the lower end of phocid and otariid hearing 
ranges. In summary, any impacts to harbor seals would be limited to 
those seals within Knik Arm (outside of any hunting area) and the very 
few takes of Steller sea lions in Knik Arm would be far removed in time 
and space from any hunting in lower Cook Inlet.

[[Page 76623]]

    The POA will communicate with representative Alaska Native 
subsistence users and Tribal members to identify and explain the 
measures that have been taken or will be taken to minimize any adverse 
effects of NES1 on the availability of marine mammals for subsistence 
uses. In addition, the POA will adhere to the following procedures 
during Tribal consultation regarding marine mammal subsistence use 
within the Project area:
    (1) Send letters to the Kenaitze, Tyonek, Knik, Eklutna, Ninilchik, 
Salamatof, and Chickaloon Tribes informing them of the proposed project 
(i.e., timing, location, and features). Include a map of the proposed 
project area; identify potential impacts to marine mammals and 
mitigation efforts, if needed, to avoid or minimize impacts; and 
inquire about possible marine mammal subsistence concerns they have.
    (2) Follow up with a phone call to the environmental departments of 
the seven Tribal entities to ensure that they received the letter, 
understand the proposed project, and have a chance to ask questions. 
Inquire about any concerns they might have about potential impacts to 
subsistence hunting of marine mammals.
    (3) Document all communication between the POA and Tribes.
    (4) If any Tribes express concerns regarding proposed project 
impacts to subsistence hunting of marine mammals, propose a Plan of 
Cooperation between the POA and the concerned Tribe(s).
    The proposed project features and activities, in combination with a 
number of actions to be taken by the POA during project implementation, 
should avoid or mitigate any potential adverse effects on the 
availability of marine mammals for subsistence uses. Furthermore, 
although construction will occur within the traditional area for 
hunting marine mammals, the proposed project area is not currently used 
for subsistence activities. In-water pile installation and removal will 
follow mitigation procedures to minimize effects on the behavior of 
marine mammals, and impacts will be temporary.
    The POA has expressed, if desired, regional subsistence 
representatives may support project marine mammal biologists during the 
monitoring program by assisting with collection of marine mammal 
observations and may request copies of marine mammal monitoring 
reports.
    Based on the description of the specified activity, the measures 
described to minimize adverse effects on the availability of marine 
mammals for subsistence purposes, and the proposed mitigation and 
monitoring measures, NMFS has preliminarily determined that there will 
not be an unmitigable adverse impact on subsistence uses from the POA's 
proposed activities.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA; 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS Office of Protected Resources (OPR) consults internally whenever 
we propose to authorize take for endangered or threatened species, in 
this case with the NMFS Alaska Regional Office.
    NMFS OPR is proposing to authorize take of Mexico-North Pacific 
humpback whales (including individuals from the Mexico DPS), CIBWs, and 
western DPS Steller sea lions, which are listed under the ESA. NMFS OPR 
has requested initiation of section 7 consultation with the issuance of 
this IHA. NMFS will conclude the ESA consultation prior to reaching a 
determination regarding the proposed issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to the POA for conducting construction and demolition 
activities in Anchorage Alaska from April 1, 2024 through March 31, 
2025, provided the previously mentioned mitigation, monitoring, and 
reporting requirements are incorporated. A draft of the proposed IHA 
can be found at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.

Request for Public Comments

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

    Dated: October 30, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-24238 Filed 11-3-23; 8:45 am]
BILLING CODE 3510-22-P