Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Wharf Construction Project, 29705-29731 [2013-12053]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 78, Number 98 (Tuesday, May 21, 2013)]
[Notices]
[Pages 29705-29731]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-12053]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XC646


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Wharf Construction Project

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments.

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SUMMARY: NMFS has received an application from the U.S. Navy (Navy) for 
an Incidental Harassment Authorization (IHA) to take marine mammals, by 
harassment, incidental to construction activities as part of a wharf 
construction project. Pursuant to the Marine Mammal Protection Act 
(MMPA), NMFS is requesting comments on its proposal to issue an IHA to 
the Navy to take, by Level B Harassment only, six species of marine 
mammals during the specified activity.

DATES: Comments and information must be received no later than June 20, 
2013.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, Chief, Permits and Conservation Division, Office of Protected 
Resources, National Marine Fisheries Service, 1315 East-West Highway, 
Silver Spring, MD 20910. The mailbox address for providing email 
comments is ITP.Laws@noaa.gov. NMFS is not responsible for email 
comments sent to addresses other than the one provided here. Comments 
sent via email, including all attachments, must not exceed a 10-
megabyte file size.
    Instructions: All comments received are a part of the public 
record. 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.
    A copy of the application as well as a list of the references used 
in this document may be obtained by writing to the address specified 
above, telephoning the contact listed below (see FOR FURTHER 
INFORMATION CONTACT), or visiting the Internet at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. Supplemental documents 
provided by the U.S. Navy may be found at the same web address. 
Documents cited in this notice may also be viewed, by appointment only, 
at the aforementioned physical address.

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

SUPPLEMENTARY INFORMATION: 

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce to allow, upon request, the 
incidental, but not intentional, taking of small numbers of marine 
mammals by U.S. citizens who engage in a specified activity (other than 
commercial fishing) within a specified geographical region if certain 
findings are made and either regulations are issued or, if the taking 
is limited to harassment, a notice of a proposed authorization 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), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings 
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103 
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.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the U.S. can apply for an authorization to 
incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of 
an application followed by a 30-day public notice and comment period on 
any proposed authorizations for the incidental harassment of marine 
mammals. Within 45 days of the close of the comment period, NMFS must 
either issue or deny the authorization. Except with respect to certain 
activities not pertinent here, the MMPA defines ``harassment'' as ``any 
act of pursuit, torment, or annoyance which (i) has the potential to 
injure a marine mammal or marine mammal stock in the wild [Level A 
harassment];

[[Page 29706]]

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].''

Summary of Request

    We received an application on December 10, 2012, from the Navy for 
the taking of marine mammals incidental to pile driving and removal in 
association with a wharf construction project in the Hood Canal at 
Naval Base Kitsap in Bangor, WA (NBKB). The Navy submitted a revised 
version of the application on May 6, 2013, which we deemed adequate and 
complete. The wharf construction project is a multi-year project; this 
IHA would cover only the second year of the project, from July 16, 
2013, through July 15, 2014. Pile driving and removal activities would 
occur only within an approved in-water work window from July 16-
February 15. Six species of marine mammals are expected to be affected 
by the specified activities: Steller sea lion (Eumetopias jubatus 
monteriensis), California sea lion (Zalophus californianus 
californianus), harbor seal (Phoca vitulina richardii), killer whale 
(transient only; Orcinus orca), Dall's porpoise (Phocoenoides dalli 
dalli), and harbor porpoise (Phocoena phocoena vomerina). These species 
may occur year-round in the Hood Canal, with the exception of the 
Steller sea lion, which is present only from fall to late spring 
(October to mid-April), and the California sea lion, which is only 
present from late summer to late spring (August to early June).
    NBKB provides berthing and support services to Navy submarines and 
other fleet assets. The Navy proposes to continue construction of the 
Explosive Handling Wharf 2 (EHW-2) facility at NBKB in order 
to support future program requirements for submarines berthed at NBKB. 
The Navy has determined that construction of EHW-2 is necessary because 
the existing EHW alone will not be able to support future program 
requirements. Under the proposed action--which includes only the 
portion of the project that would be completed under this proposed 1-
year IHA--a maximum of 195 pile driving days would occur. All piles 
would be driven with a vibratory hammer for their initial embedment 
depths, while select piles may be finished with an impact hammer for 
proofing, as necessary. Proofing involves striking a driven pile with 
an impact hammer to verify that it provides the required load-bearing 
capacity, as indicated by the number of hammer blows per foot of pile 
advancement. Sound attenuation measures (i.e., bubble curtain) would be 
used during all impact hammer operations.
    For pile driving activities, the Navy used thresholds recommended 
by NMFS for assessing project impacts, outlined later in this document. 
The Navy assumed practical spreading loss and used empirically-measured 
source levels from other 30-72 in diameter pile driving events to 
estimate potential marine mammal exposures. Predicted exposures are 
outlined later in this document. The calculations predict that only 
Level B harassment would occur associated with pile driving or 
construction activities.

Description of the Specified Activity

    NBKB is located on the Hood Canal approximately twenty miles (32 
km) west of Seattle, Washington (see Figures 2-1 through 2-4 in the 
Navy's application). The proposed actions with the potential to cause 
harassment of marine mammals within the waterways adjacent to NBKB, 
under the MMPA, are vibratory and impact pile driving operations, as 
well as vibratory removal of falsework piles, associated with the wharf 
construction project. The proposed activities that would be authorized 
by this IHA would occur between July 16, 2013, and July 15, 2014. All 
in-water construction activities within the Hood Canal are only 
permitted during July 16-February 15 in order to protect spawning fish 
populations.

Specific Geographic Region

    The Hood Canal is a long, narrow fjord-like basin of the western 
Puget Sound. Throughout its 67-mile length, the width of the canal 
varies from one to two miles and exhibits strong depth/elevation 
gradients and irregular seafloor topography in many areas. Although no 
official boundaries exist along the waterway, the northeastern section 
of the canal extending from the mouth of the canal at Admiralty Inlet 
to the southern tip of Toandos Peninsula is referred to as the northern 
Hood Canal. NBKB is located within this region (see Figures 2-1 through 
2-4 of the Navy's application). Please see Section 2 of the Navy's 
application for more information about the specific geographic region, 
including physical and oceanographic characteristics.

Project Description

    Development of necessary facilities for handling of explosive 
materials is part of the Navy's sea-based strategic deterrence mission. 
The EHW-2 would consist of two components: (1) The wharf proper (or 
Operations Area), including the warping wharf; and (2) two access 
trestles. Please see Figures 1-1 and 1-2 of the Navy's application for 
conceptual and schematic representations of the proposed EHW-2.
    The wharf proper would lie approximately 600 ft (183 m) offshore at 
water depths of 60-100 ft (18-30 m), and would consist of the main 
wharf, a warping wharf, and lightning protection towers, all pile-
supported. It would include a slip (docking area) for submarines, 
surrounded on three sides by operational wharf area. The access 
trestles would connect the wharf to the shore. There would be an 
entrance trestle and an exit trestle; these would be combined over 
shallow water to reduce overwater area. The trestles would be pile-
supported on 24-in (0.6-m) steel pipe piles driven approximately 30 ft 
(9 m) into the seafloor. Spacing between bents (rows of piles) would be 
25 ft (8 m). Concrete pile caps would be cast in place and would 
support pre-cast concrete deck sections.
    For the entire project, a total of up to 1,250 permanent piles 
ranging in size between 24-48 in (0.6-1.2 m) in diameter would be 
driven in-water to construct the wharf, with up to three vibratory rigs 
and one impact driving rig operating simultaneously. Construction would 
also involve temporary installation of up to 150 falsework piles used 
as an aid to guide permanent piles to their proper locations. Falsework 
piles, which would be removed upon installation of the permanent piles, 
would likely be steel pipe piles and would be driven and removed using 
a vibratory driver. It has not been determined exactly what parts or 
how much of the project would be constructed in any given year; 
however, a maximum of 195 days of pile driving would occur per in-water 
work window. The analysis contained herein is based upon the maximum of 
195 pile driving days, rather than any specific number of piles driven. 
Table 1 summarizes the number and nature of piles required for the 
entire project, rather than what subset of piles may be expected to be 
driven during the second year of construction proposed for this IHA.

[[Page 29707]]



        Table 1--Summary of Piles Required for Wharf Construction
                               [In total]
------------------------------------------------------------------------
                  Feature                             Quantity
------------------------------------------------------------------------
Total number of permanent in-water piles..  Up to 1,250.
Size and number of main wharf piles.......  24-in: 140.
                                            36-in (0.9-m): 157.
                                            48-in: 263.
Size and number of warping wharf piles....  24-in: 80.
                                            36-in: 190.
Size and number of lightning tower piles..  24-in: 40.
                                            36-in: 90.
Size and number of trestle piles..........  24-in: 57.
                                            36-in: 233.
Falsework piles...........................  Up to 150, 18- to 24-in.
Maximum pile driving duration.............  195 days (under 1-year IHA).
------------------------------------------------------------------------

    Pile installation would utilize vibratory pile drivers to the 
greatest extent possible, and the Navy anticipates that most piles 
would be able to be vibratory driven to within several feet of the 
required depth. Pile drivability is, to a large degree, a function of 
soil conditions and the type of pile hammer. The soil conditions 
encountered during geotechnical explorations at NBKB indicate existing 
conditions generally consist of fill or sediment of very dense 
glacially overridden soils. Recent experience at two other construction 
locations along the NBKB waterfront indicates that most piles should be 
able to be driven with a vibratory hammer to proper embedment depth. 
However, difficulties during pile driving may be encountered as a 
result of obstructions that may exist throughout the project area. Such 
obstructions may consist of rocks or boulders within the glacially 
overridden soils. If difficult driving conditions occur, increased 
usage of an impact hammer would occur.
    Unless difficult driving conditions are encountered, an impact 
hammer will only be used to proof the load-bearing capacity of 
approximately every fourth or fifth pile. The industry standard is to 
proof every pile with an impact hammer; however, in an effort to reduce 
blow counts from the impact hammer, the engineer of record has agreed 
to only proof every fourth or fifth pile. A maximum of 200 strikes 
would be required to proof each pile. Pile production rates are 
dependent upon required embedment depths, the potential for 
encountering difficult driving conditions, and the ability to drive 
multiple piles without a need to relocate the driving rig. Under best-
case scenarios (i.e., shallow piles, driving in optimal conditions, 
using multiple driving rigs), it may be possible to install enough 
pilings with the vibratory hammer that proofing may be required for up 
to five piles in a day. Under this likely scenario, with a single 
impact hammer used to proof up to five piles per day at 200 strikes per 
pile, it is estimated that up to a maximum of 1,000 strikes from an 
impact hammer would be required per day.
    If difficult subsurface driving conditions (i.e., cobble/boulder 
zones) are encountered that cause refusal with the vibratory equipment, 
it may be necessary to use an impact hammer to drive some piles for the 
remaining portion of their required depth. The worst-case scenario is 
that a pile would be driven for its entire length using an impact 
hammer. Given the uncertainty regarding the types and quantities of 
boulders or cobbles that may be encountered, and the depth at which 
they may be encountered, the number of strikes necessary to drive a 
pile its entire length could be approximately 1,000 to 2,000 strikes 
per pile. The Navy estimates that a possible worst-case daily scenario 
would require driving three piles full length (at a worst-case of 2,000 
strikes per pile) after the piles have become hung on large boulders 
early in the installation process, with proofing of an additional two 
piles (at 200 strikes each) that were able to be installed primarily 
via vibratory means. This worst-case scenario would therefore result in 
a maximum of 6,400 strikes per day. All piles driven or struck with an 
impact hammer would be surrounded by a bubble curtain or other sound 
attenuation device over the full water column to minimize in-water 
sound. Up to three vibratory rigs and one impact rig would be used at a 
time. Pile production rate (number of piles driven per day) is affected 
by many factors: size, type (vertical vs. angled), and location of 
piles; weather; number of driver rigs operating; equipment reliability; 
geotechnical (subsurface) conditions; and work stoppages for security 
or environmental reasons (such as presence of marine mammals).
    Pile driving would typically take place 6 days per week. The 
allowable season for in-water work, including pile driving, at NBKB is 
July 16 through February 15, which was established by the Washington 
Department of Fish and Wildlife in coordination with NMFS and the U.S. 
Fish and Wildlife Service (USFWS) to protect juvenile salmon. Impact 
pile driving during the first half of the in-water work window (July 16 
to September 15) would only occur between 2 hours after sunrise and 2 
hours before sunset to protect breeding marbled murrelets (an ESA-
listed bird under the jurisdiction of USFWS). Between September 16 and 
February 15, construction activities occurring in the water would occur 
during daylight hours (sunrise to sunset). Other construction (not in-
water) may occur between 7:00 a.m. and 10:00 p.m., year-round.

Description of Work Accomplished

    During the first in-water work season, the contractor completed 
installation of 184 piles to support the main segment of the access 
trestle. Driven piles ranged in size from 24-36 inches in diameter in 
depths ranging from 0 to 50 ft. A maximum of two vibratory rigs were 
operated concurrently and only one impact hammer rig was operated at a 
time. During the second season, installation of pilings for the wharf 
deck is expected to be completed. The overall intensity of pile driving 
will remain unchanged from season one. The project is scheduled for 
completion in January 2016.

Description of Sound Sources

    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per

[[Page 29708]]

unit of time and is measured in Hz or cycles per second. Wavelength is 
the distance between two peaks of a sound wave; lower frequency sounds 
have longer wavelengths than higher frequency sounds and attenuate more 
rapidly in shallower water. Amplitude is the height of the sound 
pressure wave or the `loudness' of a sound and is typically measured 
using the decibel (dB) scale. A dB is the ratio between a measured 
pressure (with sound) and a reference pressure (sound at a constant 
pressure, established by scientific standards). It is a logarithmic 
unit that accounts for large variations in amplitude; therefore, 
relatively small changes in dB ratings correspond to large changes in 
sound pressure. When referring to SPLs (SPLs; the sound force per unit 
area), sound is referenced in the context of underwater sound pressure 
to 1 microPascal ([mu]Pa). One pascal is the pressure resulting from a 
force of one newton exerted over an area of one square meter. The 
source level represents the sound level at a distance of 1 m from the 
source (referenced to 1 [mu]Pa). The received level is the sound level 
at the listener's position.
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. 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 pressures.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in all 
directions away from the source (similar to ripples on the surface of a 
pond), except in cases where the source is directional. The 
compressions and decompressions associated with sound waves are 
detected as changes in pressure by aquatic life and man-made sound 
receptors such as hydrophones. Underwater sound levels (`ambient 
sound') are comprised of multiple sources, including physical (e.g., 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
sound (e.g., vessels, dredging, aircraft, construction). Even in the 
absence of anthropogenic sound, the sea is typically a loud 
environment. A number of sources of sound are likely to occur within 
Hood Canal, including the following (Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient noise for frequencies between 200 Hz and 50 
kHz (Mitson, 1995). In general, ambient noise levels tend to increase 
with increasing wind speed and wave height. Surf noise becomes 
important near shore, with measurements collected at a distance of 8.5 
km (5.3 mi) from shore showing an increase of 10 dB in the 100 to 700 
Hz band during heavy surf conditions.
     Precipitation noise: Noise from rain and hail impacting 
the water surface can become an important component of total noise at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times.
     Biological noise: Marine mammals can contribute 
significantly to ambient noise levels, as can some fish and shrimp. The 
frequency band for biological contributions is from approximately 12 Hz 
to over 100 kHz.
     Anthropogenic noise: Sources of ambient noise related to 
human activity include transportation (surface vessels and aircraft), 
dredging and construction, oil and gas drilling and production, seismic 
surveys, sonar, explosions, and ocean acoustic studies (Richardson et 
al., 1995). Shipping noise typically dominates the total ambient noise 
for frequencies between 20 and 300 Hz. In general, the frequencies of 
anthropogenic sounds are below 1 kHz and, if higher frequency sound 
levels are created, they will attenuate (decrease) rapidly (Richardson 
et al., 1995). Known sound levels and frequency ranges associated with 
anthropogenic sources similar to those that would be used for this 
project are summarized in Table 2. Details of each of the sources are 
described in the following text.

                          Table 2--Representative Sound Levels of Anthropogenic Sources
----------------------------------------------------------------------------------------------------------------
                                             Frequency    Underwater sound level (dB
              Sound source                  range  (Hz)         re 1 [micro]Pa)                Reference
----------------------------------------------------------------------------------------------------------------
Small vessels...........................       250-1,000  151 dB rms at 1 m (3.3 ft)  Richardson et al., 1995.
Tug docking gravel barge................       200-1,000  149 dB rms at 100 m (328    Blackwell and Greene,
                                                           ft).                        2002.
Vibratory driving of 72-in (1.8 m) steel        10-1,500  180 dB rms at 10 m (33 ft)  Reyff, 2007.
 pipe pile.
Impact driving of 36-in steel pipe pile.        10-1,500  195 dB rms at 10 m........  Laughlin, 2007.
Impact driving of 66-in cast-in-steel-          10-1,500  195 dB rms at 10 m........  Reviewed in Hastings and
 shell pile.                                                                           Popper, 2005.
----------------------------------------------------------------------------------------------------------------

    In-water construction activities associated with the project would 
include impact pile driving and vibratory pile driving and removal. The 
sounds produced by these activities fall into one of two sound types: 
pulsed and non-pulsed (defined in next paragraph). The distinction 
between these two general sound types is important because they have 
differing potential to cause physical effects, particularly with regard 
to hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al., (2007) for an in-depth discussion of these concepts.
    Pulsed sounds (e.g., explosions, gunshots, sonic booms, and impact 
pile driving) are brief, broadband, atonal transients (ANSI, 1986; 
Harris, 1998) and occur either as isolated events or repeated in some 
succession. Pulsed sounds are all characterized by a relatively rapid 
rise from ambient pressure to a maximal pressure value followed by a 
decay period that may include a period of diminishing, oscillating 
maximal and minimal pressures. Pulsed sounds generally have an 
increased capacity to induce physical injury as compared with sounds 
that lack these features.
    Non-pulse (intermittent or continuous sounds) can be tonal, 
broadband, or

[[Page 29709]]

both. Some of these non-pulse sounds can be transient signals of short 
duration but without the essential properties of pulses (e.g., rapid 
rise time). Examples of non-pulse sounds include those produced by 
vessels, aircraft, machinery operations such as drilling or dredging, 
vibratory pile driving, and active sonar systems. The duration of such 
sounds, as received at a distance, can be greatly extended in a highly 
reverberant environment.
    Impact hammers operate by repeatedly dropping a heavy piston onto a 
pile to drive the pile into the substrate. Sound generated by impact 
hammers is characterized by rapid rise times and high peak levels, a 
potentially injurious combination (Hastings and Popper, 2005). 
Vibratory hammers install piles by vibrating them and allowing the 
weight of the hammer to push them into the sediment. Vibratory hammers 
produce significantly less sound than impact hammers. Peak SPLs may be 
180 dB or greater, but are generally 10 to 20 dB lower than SPLs 
generated during impact pile driving of the same-sized pile (Oestman et 
al., 2009). Rise time is slower, reducing the probability and severity 
of injury, and sound energy is distributed over a greater amount of 
time (Nedwell and Edwards, 2002; Carlson et al., 2005).

Ambient Sound

    The underwater acoustic environment consists of ambient sound, 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al., 1995). The ambient underwater sound 
level of a region is defined by the total acoustical energy being 
generated by known and unknown sources, including sounds from both 
natural and anthropogenic sources. The sum of the various natural and 
anthropogenic sound sources at any given location and time depends not 
only on the source levels (as determined by current weather conditions 
and levels of biological and shipping activity) but also on the ability 
of sound to propagate through the environment. In turn, sound 
propagation is dependent on the spatially and temporally varying 
properties of the water column and sea floor, and is frequency-
dependent. As a result of the dependence on a large number of varying 
factors, the ambient sound levels at a given frequency and location can 
vary by 10-20 dB from day to day (Richardson et al., 1995).
    Underwater ambient noise was measured at approximately 113 dB re 
1[mu]Pa rms between 50 Hz and 20 kHz during the recent Test Pile 
Program (TPP) project, approximately 1.85 mi from the project area 
(Illingworth & Rodkin, Inc., 2012). In 2009, the average broadband 
ambient underwater noise levels were measured at 114 dB re 1[mu]Pa 
between 100 Hz and 20 kHz (Slater, 2009). Peak spectral noise from 
industrial activity was noted below the 300 Hz frequency, with maximum 
levels of 110 dB re 1[mu]Pa noted in the 125 Hz band. In the 300 Hz to 
5 kHz range, average levels ranged between 83 and 99 dB re 1[mu]Pa. 
Wind-driven wave noise dominated the background noise environment at 
approximately 5 kHz and above, and ambient noise levels flattened above 
10 kHz.

Sound Attenuation Devices

    Sound levels can be greatly reduced during impact pile driving 
using sound attenuation devices. There are several types of sound 
attenuation devices including bubble curtains, cofferdams, and 
isolation casings (also called temporary noise attenuation piles 
[TNAP]), and cushion blocks. The Navy proposes to use bubble curtains, 
which create a column of air bubbles rising around a pile from the 
substrate to the water surface. The air bubbles absorb and scatter 
sound waves emanating from the pile, thereby reducing the sound energy. 
Bubble curtains may be confined or unconfined. An unconfined bubble 
curtain may consist of a ring seated on the substrate and emitting air 
bubbles from the bottom. An unconfined bubble curtain may also consist 
of a stacked system, that is, a series of multiple rings placed at the 
bottom and at various elevations around the pile. Stacked systems may 
be more effective than non-stacked systems in areas with high current 
and deep water (Oestman et al., 2009).
    A confined bubble curtain contains the air bubbles within a 
flexible or rigid sleeve made from plastic, cloth, or pipe. Confined 
bubble curtains generally offer higher attenuation levels than 
unconfined curtains because they may physically block sound waves and 
they prevent air bubbles from migrating away from the pile. For this 
reason, the confined bubble curtain is commonly used in areas with high 
current velocity (Oestman et al., 2009).
    Both environmental conditions and the characteristics of the sound 
attenuation device may influence the effectiveness of the device. 
According to Oestman et al. (2009):
     In general, confined bubble curtains attain better sound 
attenuation levels in areas of high current than unconfined bubble 
curtains. If an unconfined device is used, high current velocity may 
sweep bubbles away from the pile, resulting in reduced levels of sound 
attenuation.
     Softer substrates may allow for a better seal for the 
device, preventing leakage of air bubbles and escape of sound waves. 
This increases the effectiveness of the device. Softer substrates also 
provide additional attenuation of sound traveling through the 
substrate.
     Flat bottom topography provides a better seal, enhancing 
effectiveness of the sound attenuation device, whereas sloped or 
undulating terrain reduces or eliminates its effectiveness.
     Air bubbles must be close to the pile; otherwise, sound 
may propagate into the water, reducing the effectiveness of the device.
     Harder substrates may transmit ground-borne sound and 
propagate it into the water column.
    The literature presents a wide array of observed attenuation 
results for bubble curtains (e.g., Oestman et al., 2009, Coleman, 2011, 
Caltrans, 2012). The variability in attenuation levels is due to 
variation in design, as well as differences in site conditions and 
difficulty in properly installing and operating in-water attenuation 
devices. As a general rule, reductions of greater than 10 dB cannot be 
reliably predicted. The TPP reported a range of measured values for 
realized attenuation mostly within 6 to 12 dB (Illingworth & Rodkin, 
Inc., 2012). For 36-inch piles the average peak and rms reduction with 
use of the bubble curtain was 8 dB, where the averages of all bubble-on 
and bubble-off data were compared. For 48-inch piles, the average SPL 
reduction with use of a bubble curtain was 6 dB for average peak values 
and 5 dB for rms values (see Table 3). To avoid loss of attenuation 
from design and implementation errors, the Navy has required specific 
bubble curtain design specifications, including testing requirements 
for air pressure and flow prior to initial impact hammer use, and a 
requirement for placement on the substrate. We considered TPP 
measurements (approximately 7 dB overall) and other monitored projects 
(typically at least 8 dB realized attenuation), and determined that 8 
dB may be the best estimate of average SPL (rms) reduction. In looking 
at other monitored projects prior to completion of the TPP, the Navy 
determined with our concurrence that an assumption of 10 dB realized 
attenuation was realistic. Therefore, a 10 dB reduction was used in the 
Navy's analysis of pile driving noise in the initial environmental 
analyses for the EHW-2 project, and the Navy included a contract 
performance requirement to achieve a 10 dB reduction during EHW-2 pile 
driving. The Navy is currently reviewing acoustical data from the first 
year of

[[Page 29710]]

EHW-2 construction to determine whether the contractor successfully met 
the requirement. If the data show that the 10 dB assumption is not 
consistently achievable, this assumption will be changed to 8 dB in 
assessing the potential effects of pile driving during future years of 
EHW-2 construction.

Sound Thresholds

    NMFS uses generic sound exposure thresholds to determine when an 
activity that produces sound might result in impacts to a marine mammal 
such that a take by harassment might occur. To date, no studies have 
been conducted that examine impacts to marine mammals from pile driving 
sounds from which empirical sound thresholds have been established. 
Current NMFS practice (in relation to the MMPA) regarding exposure of 
marine mammals to sound is that cetaceans and pinnipeds exposed to 
impulsive sounds of 180 and 190 dB rms or above, respectively, are 
considered to have been taken by Level A (i.e., injurious) harassment. 
Behavioral harassment (Level B) is considered to have occurred when 
marine mammals are exposed to sounds at or above 160 dB rms for impulse 
sounds (e.g., impact pile driving) and 120 dB rms for continuous sound 
(e.g., vibratory pile driving), but below injurious thresholds. For 
airborne sound, pinniped disturbance from haul-outs has been documented 
at 100 dB (unweighted) for pinnipeds in general, and at 90 dB 
(unweighted) for harbor seals. NMFS uses these levels as guidelines to 
estimate when harassment may occur.

Distance to Sound Thresholds

    Underwater Sound Propagation Formula--Pile driving would generate 
underwater noise that potentially could result in disturbance to marine 
mammals in the project area. Transmission loss (TL) is the decrease in 
acoustic intensity as an acoustic pressure wave propagates out from a 
source. TL parameters vary with frequency, temperature, sea conditions, 
current, source and receiver depth, water depth, water chemistry, and 
bottom composition and topography. The general formula for underwater 
TL is:

TL = B * log10(R1/R2),

Where

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

This formula neglects loss due to scattering and absorption, which is 
assumed to be zero here. The degree to which underwater sound 
propagates away from a sound source is dependent on a variety of 
factors, most notably by the water bathymetry and presence or absence 
of reflective or absorptive conditions including in-water structures 
and sediments. Spherical spreading occurs in a perfectly unobstructed 
(free-field) environment not limited by depth or water surface, 
resulting in a 6 dB reduction in sound level for each doubling of 
distance from the source (20*log[range]). Cylindrical spreading occurs 
in an environment in which sound propagation is bounded by the water 
surface and sea bottom, resulting in a reduction of 3 dB in sound level 
for each doubling of distance from the source (10*log[range]). A 
practical spreading value of 15 is often used under conditions, such as 
Hood Canal, where water increases with depth as the receiver moves away 
from the shoreline, resulting in an expected propagation environment 
that would lie between spherical and cylindrical spreading loss 
conditions. Practical spreading loss (4.5 dB reduction in sound level 
for each doubling of distance) is assumed here.

    Underwater Sound--The intensity of pile driving sounds is greatly 
influenced by factors such as the type of piles, hammers, and the 
physical environment in which the activity takes place. A large 
quantity of literature regarding SPLs recorded from pile driving 
projects is available for consideration. In order to determine 
reasonable SPLs and their associated effects on marine mammals that are 
likely to result from pile driving at NBKB, studies with similar 
properties to the proposed action were evaluated, including 
measurements conducted for driving of steel piles at NBKB as part of 
the TPP (Illingworth & Rodkin, Inc., 2012). During the TPP, SPLs from 
driving of 24-, 36-, and 48-in piles by impact and vibratory hammers 
were measured. Sound levels associated with vibratory pile removal are 
assumed to be the same as those during vibratory installation (Reyff, 
2007)--which is likely a conservative assumption--and have been taken 
into consideration in the modeling analysis. Overall, studies which met 
the following parameters were considered: (1) Pile size and materials: 
Steel pipe piles (30-72 in diameter); (2) Hammer machinery: Vibratory 
and impact hammer; and (3) Physical environment: shallow depth (less 
than 100 ft [30 m]).

                                  Table 3--Underwater SPLS From Monitored Construction Activities Using Impact Hammers
--------------------------------------------------------------------------------------------------------------------------------------------------------
         Project and location               Pile size and type            Water depth                               Measured SPLs
--------------------------------------------------------------------------------------------------------------------------------------------------------
Eagle Harbor Maintenance Facility, WA   30-in (0.8 m) steel pipe   10 m (33 ft)............  192 dB re 1 [micro]Pa (rms) at 10 m (33 ft).
 \1\.                                    pile.
Friday Harbor Ferry Terminal, WA \2\..  30-in steel pipe pile....  10 m....................  196 dB re 1 [micro]Pa (rms) at 10 m.
California \3\........................  36-in steel pipe pile....  10 m....................  193 dB re 1 [micro]Pa (rms) at 10 m.
Mukilteo Test Piles, WA \4\...........  36-in steel pipe pile....  7.3 m (24 ft)...........  195 dB re 1 [micro]Pa (rms) at 10 m.
Anacortes Ferry, WA \5\...............  36-in steel pipe pile....  12.8 m (42 ft)..........  199 dB re 1 [micro]Pa (rms) at 10 m.
Carderock Pier, NBKB, WA \6\..........  42-in steel pipe pile....  14-22 m (48-70 ft)......  195 dB re 1 [micro]Pa (rms) at 10 m.
Russian River, CA \3\.................  48-in steel pipe pile....  2 m (6.6 ft)............  195 dB re 1 [micro]Pa (rms) at 10 m.
California \3\........................  60-in cast-in-steel-shell  10 m....................  195 dB re 1 [micro]Pa (rms) at 10 m.
Richmond-San Rafael Bridge, CA \3\....  66-in steel pipe pile....  4 m (13 ft).............  195 dB re 1 [micro]Pa (rms) at 10 m.
Test Pile Program, NBKB \7\...........  36-in steel pipe pile....  Avg of mid- and deep-     196 dB re 1 [micro]Pa (rms) at 10 m.
                                                                    depth.
Test Pile Program, NBKB \7\...........  48-in steel pipe pile....  Avg of mid- and deep-     194 dB re 1 [micro]Pa (rms) at 10 m.
                                                                    depth.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sources: \1\ MacGillivray and Racca, 2005; \2\ Laughlin, 2005; \3\ Reyff, 2007; \4\ MacGillivray, 2007; \5\ Sexton, 2007; \6\ Navy, 2009; \7\
  Illingworth & Rodkin, Inc., 2012.

    The tables presented here detail representative pile driving SPLs 
that have been recorded from similar construction activities in recent 
years. Due to the similarity of these actions and the Navy's proposed 
action, these

[[Page 29711]]

values represent reasonable SPLs which could be anticipated, and which 
were used in the acoustic modeling and analysis. Table 3 represents 
SPLs that may be expected during pile installation using an impact 
hammer. Table 4 represents SPLs that may be expected during pile 
installation using a vibratory hammer. For impact driving, a source 
value of 195 dB RMS re 1 [mu]Pa at 10 m was the average value reported 
from the listed studies, and is consistent with measurements from the 
TPP and Carderock Pier pile driving projects at NBKB, which had similar 
pile materials (48- and 42-inch hollow steel piles, respectively), 
water depth, and substrate type as the EHW-2 project site. For 
vibratory pile driving, the Navy selected the most conservative value 
(72-inch piles; 180 dB rms re 1 [mu]Pa at 10 m) available when 
initially assessing EHW-2 project impacts, prior to the first year of 
the project. Since then, data from the TPP have become available that 
indicate, on average, a lower source level for vibratory pile driving 
(172 dB rms re 1 [mu]Pa for 48-inch steel piles). However, for 
consistency we have maintained the initial conservative assumption 
regarding source level for vibratory driving.

             Table 4--Underwater SPLS From Monitored Construction Activities Using Vibratory Hammers
----------------------------------------------------------------------------------------------------------------
                                  Pile size and
     Project and location              type           Water depth                    Measured SPLs
----------------------------------------------------------------------------------------------------------------
Vashon Terminal, WA \1\.......  30-in (0.8 m)      6 m..............  165 dB re 1 [micro]Pa (rms) at 11 m.
                                 steel pipe pile.
Keystone Terminal, WA \2\.....  30-in steel pipe   8 m..............  165 dB re 1 [micro]Pa (rms) at 10 m.
                                 pile.
California \3\................  36-in steel pipe   5 m..............  170 dB re 1 [micro]Pa (rms) at 10 m.
                                 pile.
California \3\................  36-in steel pipe   5 m..............  175 dB re 1 [micro]Pa (rms) at 10 m.
                                 pile.
California \3\................  72-in steel pipe   5 m..............  170 dB re 1 [micro]Pa (rms) at 10 m.
                                 pile.
California \3\................  72-in steel pipe   5 m..............  180 dB re 1 [micro]Pa (rms) at 10 m.
                                 pile.
Test Pile Program, NBKB \4\...  36-in steel pipe   Avg of mid- and    169 dB re 1 [micro]Pa (rms) at 10 m.
                                 pile.              deep-depth.
Test Pile Program, NBKB \4\...  48-in steel pipe   Avg of mid- and    172 dB re 1 [micro]Pa (rms) at 10 m.
                                 pile.              deep-depth.
----------------------------------------------------------------------------------------------------------------
Sources: \1\ Laughlin, 2010a; \2\ Laughlin, 2010b; \3\ Reyff, 2007; \4\ Illingworth & Rodkin, Inc., 2012.

    As described previously in this document, sound attenuation 
measures, including bubble curtains, can be employed during impact pile 
driving to reduce the high source pressures. For the wharf construction 
project, the Navy intends to employ sound reduction techniques during 
impact pile driving, including the use of sound attenuation systems 
(e.g., bubble curtain). See ``Proposed Mitigation'', later in this 
document, for more details on the impact reduction and mitigation 
measures proposed. The calculations of the distances to the marine 
mammal sound thresholds were calculated for impact installation with 
the assumption of a 10 dB reduction in source levels from the use of 
sound attenuation devices, and the Navy used the mitigated distances 
for impact pile driving for all analysis in their application.
    All calculated distances to and the total area encompassed by the 
marine mammal sound thresholds are provided in Table 5. The Navy used 
source values of 185 dB for impact driving (the mean SPL of the values 
presented in Table 3, less 10 dB of sound attenuation from use of a 
bubble curtain or similar device) and 180 dB for vibratory driving (the 
worst-case value from Table 4). Under likely construction scenarios, up 
to three vibratory drivers would operate simultaneously with one impact 
driver. Although radial distance and area associated with the zone 
ensonified to 160 dB (the behavioral harassment threshold for pulsed 
sounds, such as those produced by impact driving) are presented in 
Table 5, this zone would be subsumed by the 120 dB zone produced by 
vibratory driving. Thus, behavioral harassment of marine mammals 
associated with impact driving is not considered further here. Since 
the 160 dB threshold and the 120 dB threshold both indicate behavioral 
harassment, pile driving effects in the two zones are equivalent. 
Although such a day is not planned, if only the impact driver was 
operated on a given day, incidental take on that day would likely be 
lower because the area ensonified to levels producing Level B 
harassment would be smaller (although actual take would be determined 
by the numbers of marine mammals in the area on that day). The use of 
multiple vibratory rigs at the same time would result in a small 
additive effect with regard to produced SPLs; however, because the 
sound field produced by vibratory driving would be truncated by land in 
the Hood Canal, no increase in actual sound field produced would occur. 
There would be no overlap in the 190/180-dB sound fields produced by 
rigs operating simultaneously.

  Table 5--Calculated Distance(s) to and Area Encompassed by Underwater
         Marine Mammal Sound Thresholds During Pile Installation
------------------------------------------------------------------------
           Threshold                     Distance           Area, km\2\
------------------------------------------------------------------------
Impact driving, pinniped injury  4.9 m..................          0.0001
 (190 dB).
Impact driving, cetacean injury  22 m...................          0.002
 (180 dB).
Impact driving, disturbance      724 m..................          1.65
 (160 dB)\2\.
Vibratory driving, pinniped      2.1 m..................        < 0.0001
 injury (190 dB).
Vibratory driving, cetacean      10 m...................          0.0003
 injury (180 dB).
Vibratory driving, disturbance   13,800 m\3\............         41.4
 (120 dB).
------------------------------------------------------------------------
\1\ SPLs used for calculations were: 185 dB for impact and 180 dB for
  vibratory driving.
\2\ Area of 160-dB zone presented for reference. Estimated incidental
  take calculated on basis of larger 120-dB zone.
\3\ Hood Canal average width at site is 2.4 km (1.5 mi), and is fetch
  limited from N to S at 20.3 km (12.6 mi). Calculated range (over 222
  km) is greater than actual sound propagation through Hood Canal due to
  intervening land masses. 13.8 km (8.6 mi) is the greatest line-of-
  sight distance from pile driving locations unimpeded by land masses,
  which would block further propagation of sound.


[[Page 29712]]

    Hood Canal does not represent open water, or free field, 
conditions. Therefore, sounds would attenuate as they encounter land 
masses or bends in the canal. As a result, the calculated distance and 
areas of impact for the 120 dB threshold cannot actually be attained at 
the project area. See Figure 6-1 of the Navy's application for a 
depiction of the size of areas in which each underwater sound threshold 
is predicted to occur at the project area due to pile driving.
    Airborne Sound--Pile driving can generate airborne sound that could 
potentially result in disturbance to marine mammals (specifically, 
pinnipeds) which are hauled out or at the water's surface. As a result, 
the Navy analyzed the potential for pinnipeds hauled out or swimming at 
the surface near NBKB to be exposed to airborne SPLs that could result 
in Level B behavioral harassment. NMFS assumes for purposes of the MMPA 
that behavioral disturbance can occur upon exposure to sounds above 100 
dB re 20 [micro]Pa rms (unweighted) for all pinnipeds, except harbor 
seals. For harbor seals, the threshold is 90 dB re 20 [micro]Pa rms 
(unweighted).
    As was discussed for underwater sound from pile driving, the 
intensity of pile driving sounds is greatly influenced by factors such 
as the type of piles, hammers, and the physical environment in which 
the activity takes place. In order to determine reasonable airborne 
SPLs and their associated effects on marine mammals that are likely to 
result from pile driving at NBKB, studies with similar properties to 
the proposed action, as described previously, were evaluated. Table 6 
details representative pile driving activities that have occurred in 
recent years. Due to the similarity of these actions and the Navy's 
proposed action, they represent reasonable SPLs which could be 
anticipated. During the TPP, vibratory driving was measured at 102 dB 
re 20 [micro]Pa rms at 15 m and impact driving at 109 dB re 20 
[micro]Pa rms at 15 m. The values shown in Table 6 were retained for 
impact assessment because the value for impact driving, as used in the 
combined rig scenario, results in a more conservative ZOI than does the 
TPP measurement.

                                               Table 6--Airborne Spls From Similar Construction Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
       Project & location         Pile size & type            Method             Water depth                          Measured SPLs
--------------------------------------------------------------------------------------------------------------------------------------------------------
Northstar Island, AK \1\.......  42-in (1.1 m)       Impact.................  Approximately 12   97 dB re 20 [micro]Pa (rms) at 160 m (525 ft).
                                  steel pipe pile.                             m (40 ft).
Keystone Ferry Terminal, WA \3\  30-in (0.8 m)       Vibratory..............  Approximately 9 m  97 dB re 20 [micro]Pa (rms) at 13 m (40 ft).
                                  steel pipe pile.                             (30 ft).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sources: Blackwell et al., 2004; Laughlin, 2010b.

    Based on these values and the assumption of spherical spreading 
loss, distances to relevant thresholds and associated areas of 
ensonification under the multi-rig scenario (i.e., combined impact and 
vibratory driving) are presented in Table 7. There are no haul-out 
locations within these zones, which are encompassed by the zones 
estimated for underwater sound. Protective measures would be in place 
out to the distances calculated for the underwater thresholds, and the 
distances for the airborne thresholds would be covered fully by 
mitigation and monitoring measures in place for underwater sound 
thresholds. Construction sound associated with the project would not 
extend beyond the buffer zone for underwater sound that would be 
established to protect pinnipeds. No haul-outs or rookeries are located 
within the airborne harassment radii. See Figure 6-2 of the Navy's 
application for a depiction of the size of areas in which each airborne 
sound threshold is predicted to occur at the project area due to pile 
driving. We recognize that pinnipeds in water that are within the area 
of ensonification for airborne sound could be incidentally taken by 
either underwater or airborne sound or both. We consider these 
incidences of harassment to be accounted for in the take estimates for 
underwater sound.

           Table 7--Distances to Relevant Sound Thresholds and Areas of Ensonification, Airborne Sound
----------------------------------------------------------------------------------------------------------------
                                                                                          Distance to threshold
                                                                                         (m) and associated area
                    Group                      Threshold, re 20 [mu]Pa rms (unweighted)     of ensonification
                                                                                          (km\2\); combined rig
                                                                                          scenario (worst-case)
----------------------------------------------------------------------------------------------------------------
Harbor seals................................  90 dB....................................               361, 0.07
California sea lions........................  100 dB...................................               114, 0.005
----------------------------------------------------------------------------------------------------------------

Description of Marine Mammals in the Area of the Specified Activity

    There are seven marine mammal species, four cetaceans and three 
pinnipeds, which may inhabit or transit through the waters nearby NBKB 
in the Hood Canal. These include the transient killer whale, harbor 
porpoise, Dall's porpoise, Steller sea lion, California sea lion, 
harbor seal, and humpback whale (Megaptera novaeangliae). The Steller 
sea lion and humpback whale are the only marine mammals that may occur 
within the Hood Canal that are listed under the Endangered Species Act 
(ESA); the humpback whale is listed as endangered and the eastern 
distinct population segment (DPS) of Steller sea lion is listed as 
threatened. The humpback whale is not typically present in Hood Canal, 
with no confirmed sightings found in the literature or the Orca Network 
database (https://www.orcanetwork.org/) prior to January and February 
2012, when one individual was observed repeatedly over a period of 
several weeks. No sightings have been recorded since that time and we 
consider the humpback whale to be a rare visitor to Hood Canal at most. 
While the southern resident killer whale is resident to the inland 
waters of Washington and British Columbia, it has not been observed in 
the Hood Canal in over 18 years. These two species have therefore been 
excluded from further analysis.
    This section summarizes the population status and abundance of 
these species. We have reviewed the Navy's detailed species 
descriptions,

[[Page 29713]]

including life history information, for accuracy and completeness and 
refer the reader to Sections 3 and 4 of the Navy's application instead 
of reprinting the information here. Table 9 lists the marine mammal 
species with expected potential for occurrence in the vicinity of NBKB 
during the project timeframe. The following information is summarized 
largely from NMFS Stock Assessment Reports.

                    Table 8--Marine Mammals Present in the Hood Canal in the Vicinity of NBKB
----------------------------------------------------------------------------------------------------------------
                                       Stock abundance\1\ (CV,   Relative occurrence in
               Species                          Nmin)                  Hood Canal          Season of occurrence
----------------------------------------------------------------------------------------------------------------
Steller sea lion Eastern U.S. DPS....  58,334-72,223 \2\......  Seasonal; Occasional...  Fall to late spring
                                                                                          (Oct to May).
California sea lion U.S. Stock.......  296,750 (n/a, 153,337).  Seasonal; Common.......  Fall to late spring
                                                                                          (Aug to early June).
Harbor seal WA inland waters stock...  14,612 \2\ (0.15,        Common.................  Year-round; resident
                                        12,844).                                          species in Hood Canal.
Killer whale West Coast transient      354 (n/a)..............  Rare...................  Year-round (but last
 stock.                                                                                   observed in 2005).
Dall's porpoise CA/OR/WA stock.......  42,000 (0.33, 32,106)..  Rare...................  Year-round (but last
                                                                                          observed in 2008)
Harbor porpoise WA inland waters       10,682.................  Possible regular to      Year-round.
 stock.                                (0.38, 7,841)..........   occasional presence.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: https://www.nmfs.noaa.gov/pr/sars/species.htm. CV is
  coefficient of variation; Nmin is the minimum estimate of stock abundance.
This abundance estimate is greater than eight years old and is therefore not considered current.

Steller Sea Lion

    Steller sea lions are distributed mainly around the coasts to the 
outer continental shelf along the North Pacific rim from northern 
Hokkaido, Japan through the Kuril Islands and Okhotsk Sea, Aleutian 
Islands and central Bering Sea, southern coast of Alaska and south to 
California. Based on distribution, population response, phenotypic, and 
genotypic data, two separate stocks of Steller sea lions are recognized 
within U.S. waters, with the population divided into western and 
eastern distinct population segments (DPSs) at 144[deg] W (Cape 
Suckling, Alaska) (Loughlin, 1997). The eastern DPS extends from 
California to Alaska, including the Gulf of Alaska, and is the only 
stock that may occur in the Hood Canal.
    Steller sea lions were listed as threatened range-wide under the 
ESA in 1990. After division into two stocks, the western stock was 
listed as endangered in 1997, while the eastern stock remained 
classified as threatened. NMFS proposed on April 18, 2012, that the 
eastern stock is recovered and should be delisted. Pending a final 
decision on that proposal, the stock remains designated as depleted 
under the MMPA by default due to its threatened status under the ESA. 
However, the minimum estimated annual level of human-caused mortality 
(59.1) is significantly less than the calculated potential biological 
removal (PBR) of 2,378 animals. The stock has shown a consistent, long-
term rate of increase, which may indicate that it is reaching optimum 
sustainable population (OSP) size (Allen and Angliss, 2013).
    The most recent population estimate for the eastern stock is 
estimated to be within the range 58,334 to 72,223 (Allen and Angliss, 
2013). Calkins and Pitcher (1982) and Pitcher et al., (2007) concluded 
that the total Steller sea lion population could be estimated by 
multiplying pup counts by a factor based on the birth rate, sex and age 
structure, and growth rate of the population. This range is determined 
by multiplying the most recent pup counts available by region, from 
2006 (British Columbia) and 2009 (U.S.), by pup multipliers of either 
4.2 or 5.2 (Pitcher et al., 2007). The pup multipliers varied depending 
on the vital rate parameter that resulted in the growth rate: As low as 
4.2 if it were due to high fecundity, and as high as 5.2 if it were due 
to low juvenile mortality. These are not minimum population estimates, 
since they are extrapolated from pup counts from photographs taken in 
2006-2009, and demographic parameters are estimated for an increasing 
population. The minimum population, which is estimated at 52,847 
individuals, was calculated by adding the most recent non-pup and pup 
counts from all sites surveyed; this estimate is not corrected for 
animals at sea. The most recent minimum count for Steller sea lions in 
Washington was 516 in 2001 (Pitcher et al., 2007).
    The abundance of the Eastern DPS of Steller sea lions is increasing 
throughout the northern portion of its range (Southeast Alaska and 
British Columbia; Merrick et al., 1992; Sease et al., 2001; Olesiuk and 
Trites, 2003; Olesiuk, 2008; NMFS, 2008), and stable or increasing 
slowly in the central portion (Oregon through central California; NMFS, 
2008). In the southern end of its range (Channel Islands in southern 
California; LeBoeuf et al., 1991), it has declined significantly since 
the late 1930s, and several rookeries and haul-outs have been 
abandoned. Changes in ocean conditions (e.g., warmer temperatures) may 
be contributing to habitat changes that favor California sea lions over 
Steller sea lions in the southern portion of the Steller's range (NMFS, 
2008). Between the 1970s and 2002, the average annual population growth 
rate of eastern Steller sea lions was 3.1 percent (Pitcher et al., 
2007). Pitcher et al. (2007) concluded this rate did not represent a 
maximum rate of increase, though, and the maximum theoretical net 
productivity rate for pinnipeds (12 percent) is considered appropriate 
(Allen and Angliss, 2013).
    Data from 2005-10 show a total mean annual mortality rate of 5.71 
(CV = 0.23) sea lions per year from observed fisheries and 11.25 
reported takes per year that could not be assigned to specific 
fisheries, for a total from all fisheries of 17 eastern Steller sea 
lions (Allen and Angliss, 2013). In addition, opportunistic 
observations and stranding data indicate that an additional 28.8 
animals are killed or seriously injured each year through interaction 
with commercial and recreational troll fisheries and by entanglement. 
For the most recent years from which data are available (2004-08), 11.9 
animals were taken per year by subsistence harvest in Alaska. Sea lion 
deaths are also known to occur because of illegal shooting, vessel 
strikes, or capture in research gear and other traps, totaling 1.4 
animals per year from 2006-

[[Page 29714]]

10. The total annual human-caused mortality is a minimum estimate 
because takes via fisheries interactions and subsistence harvest in 
Canada are poorly known, although are believed to be small.
    The eastern stock breeds in rookeries located in southeast Alaska, 
British Columbia, Oregon, and California. There are no known breeding 
rookeries in Washington (Allen and Angliss, 2013) but eastern stock 
Steller sea lions are present year-round along the outer coast of 
Washington, including immature animals or non-breeding adults of both 
sexes. In Washington, Steller sea lions primarily occur at haul-out 
sites along the outer coast from the Columbia River to Cape Flattery 
and in inland waters sites along the Vancouver Island coastline of the 
Strait of Juan de Fuca (Jeffries et al., 2000; COSEWIC, 2003; Olesiuk, 
2008). Numbers vary seasonally in Washington waters with peak numbers 
present during the fall and winter months (Jeffries et al., 2000). At 
NBKB, Steller sea lions have been observed hauled out on submarines at 
Delta Pier on several occasions during fall through spring months, 
beginning in 2008, with up to six individuals observed.

Harbor Seal

    Harbor seals inhabit coastal and estuarine waters and shoreline 
areas of the northern hemisphere from temperate to polar regions. The 
eastern North Pacific subspecies is found from Baja California north to 
the Aleutian Islands and into the Bering Sea. Multiple lines of 
evidence support the existence of geographic structure among harbor 
seal populations from California to Alaska (Carretta et al., 2011). 
However, because stock boundaries are difficult to meaningfully draw 
from a biological perspective, three separate harbor seal stocks are 
recognized for management purposes along the west coast of the 
continental U.S.: (1) Inland waters of Washington (including Hood 
Canal, Puget Sound, and the Strait of Juan de Fuca out to Cape 
Flattery), (2) outer coast of Oregon and Washington, and (3) California 
(Carretta et al., 2011). Multiple stocks are recognized in Alaska. 
Samples from Washington, Oregon, and California demonstrate a high 
level of genetic diversity and indicate that the harbor seals of 
Washington inland waters possess unique haplotypes not found in seals 
from the coasts of Washington, Oregon, and California (Lamont et al., 
1996). Only the Washington inland waters stock may be found in the 
project area.
    Washington inland waters harbor seals are not protected under the 
ESA or listed as depleted under the MMPA. Because there is no current 
abundance estimate for this stock, there is no current estimate of 
potential biological removal (PBR). However, because annual human-
caused mortality (13) is significantly less than the previously 
calculated PBR (771) the stock is not considered strategic under the 
MMPA. The stock is considered to be within its optimum sustainable 
population (OSP) level.
    The best abundance estimate of the Washington inland waters stock 
of harbor seals is 14,612 (CV = 0.15) and the minimum population size 
of this stock is 12,884 individuals (Carretta et al., 2011). Aerial 
surveys of harbor seals in Washington were conducted during the pupping 
season in 1999, during which time the total numbers of hauled-out seals 
(including pups) were counted (Jeffries et al., 2003). Radio-tagging 
studies conducted at six locations collected information on harbor seal 
haul-out patterns in 1991-92, resulting in a correction factor of 1.53 
(CV = 0.065) to account for animals in the water which are missed 
during the aerial surveys (Huber et al., 2001), which, coupled with the 
aerial survey counts, provides the abundance estimate. Because the 
estimate is greater than eight years old, NMFS does not consider it 
current. However, it does represent the best available information 
regarding stock abundance. Harbor seal counts in Washington State 
increased at an annual rate of ten percent from 1991-96 (Jeffries et 
al., 1997). However, a logistic model fit to abundance data from 1978-
99 resulted in an estimated maximum net productivity rate of 12.6 
percent (95% CI = 9.4-18.7%) and the population is thought to be stable 
(Jeffries et al., 2003).
    Historical levels of harbor seal abundance in Washington are 
unknown. The population was apparently greatly reduced during the 1940s 
and 1950s due to a state-financed bounty program and remained low 
during the 1970s before rebounding to current levels (Carretta et al., 
2011). Data from 2004-08 indicate that a minimum of 3.8 harbor seals 
are killed annually in Washington inland waters commercial fisheries 
(Carretta et al., 2011). Animals captured east of Cape Flattery are 
assumed to belong to this stock. The estimate is considered a minimum 
because there are likely additional animals killed in unobserved 
fisheries and because not all animals stranding as a result of 
fisheries interactions are likely to be recorded. Another 9.2 harbor 
seals per year are estimated to be killed as a result of various non-
fisheries human interactions (Carretta et al., 2011). Tribal 
subsistence takes of this stock may occur, but no data on recent takes 
are available.
    Harbor seals are the most abundant marine mammal in Hood Canal, 
where they can occur anywhere year-round, and are the only pinniped 
that breeds in inland Washington waters and the only species of marine 
mammal that is considered resident in the Hood Canal (Jeffries et al., 
2003). They are year-round, non-migratory residents, pup (i.e., give 
birth) in Hood Canal, and the population is considered closed, meaning 
that they do not have much movement outside of Hood Canal (London, 
2006). Surveys in the Hood Canal from the mid-1970s to 2000 show a 
fairly stable population between 600-1,200 seals, and the abundance of 
harbor seals in Hood Canal has likely stabilized at its carrying 
capacity of approximately 1,000 seals (Jeffries et al., 2003).
    Harbor seals were consistently sighted during Navy surveys and were 
found in all marine habitats including nearshore waters and deeper 
water, and have been observed hauled out on manmade objects such as 
buoys. Harbor seals were commonly observed in the water during 
monitoring conducted for other projects at NBKB in 2011. During most of 
the year, all age and sex classes (except newborn pups) could occur in 
the project area throughout the period of construction activity. Since 
there are no known pupping sites in the vicinity of the project area, 
harbor seal neonates would not generally be expected to be present 
during pile driving. Otherwise, during most of the year, all age and 
sex classes could occur in the project area throughout the period of 
construction activity. Harbor seal numbers increase from January 
through April and then decrease from May through August as the harbor 
seals move to adjacent bays on the outer coast of Washington for the 
pupping season. From April through mid-July, female harbor seals haul 
out on the outer coast of Washington at pupping sites to give birth. 
The main haul-out locations for harbor seals in Hood Canal are located 
on river delta and tidal exposed areas, with the closest haul-out to 
the project area being approximately ten miles (16 km) southwest of 
NBKB at Dosewallips River mouth, outside the potential area of effect 
for this project (London, 2006; see Figure 4-1 of the Navy's 
application).

California Sea Lion

    California sea lions range from the Gulf of California north to the 
Gulf of Alaska, with breeding areas located in the Gulf of California, 
western Baja California, and southern California. Five

[[Page 29715]]

genetically distinct geographic populations have been identified: (1) 
Pacific Temperate, (2) Pacific Subtropical, (3) Southern Gulf of 
California, (4) Central Gulf of California and (5) Northern Gulf of 
California (Schramm et al., 2009). Rookeries for the Pacific Temperate 
population are found within U.S. waters and just south of the U.S.-
Mexico border, and animals belonging to this population may be found 
from the Gulf of Alaska to Mexican waters off Baja California. For 
management purposes, a stock of California sea lions comprising those 
animals at rookeries within the U.S. is defined (i.e., the U.S. stock 
of California sea lions) (Carretta et al., 2011). Pup production at the 
Coronado Islands rookery in Mexican waters is considered an 
insignificant contribution to the overall size of the Pacific Temperate 
population (Lowry and Maravilla-Chavez, 2005).
    California sea lions are not protected under the ESA or listed as 
depleted under the MMPA. Total annual human-caused mortality (at least 
431) is substantially less than the potential biological removal (PBR, 
estimated at 9,200 per year); therefore, California sea lions are not 
considered a strategic stock under the MMPA. There are indications that 
the California sea lion may have reached or is approaching carrying 
capacity, although more data are needed to confirm that leveling in 
growth persists (Carretta et al., 2011).
    The best abundance estimate of the U.S. stock of California sea 
lions is 296,750 and the minimum population size of this stock is 
153,337 individuals (Carretta et al., 2011). The entire population 
cannot be counted because all age and sex classes are never ashore at 
the same time; therefore, the best abundance estimate is determined 
from the number of births and the proportion of pups in the population, 
with censuses conducted in July after all pups have been born. 
Specifically, the pup count for rookeries in southern California from 
2008 was adjusted for pre-census mortality and then multiplied by the 
inverse of the fraction of newborn pups in the population (Carretta et 
al., 2011). The minimum population size was determined from counts of 
all age and sex classes that were ashore at all the major rookeries and 
haul-out sites in southern and central California during the 2007 
breeding season, including all California sea lions counted during the 
July 2007 census at the Channel Islands in southern California and at 
haul-out sites located between Point Conception and Point Reyes, 
California (Carretta et al., 2011). An additional unknown number of 
California sea lions are at sea or hauled out at locations that were 
not censused and are not accounted for in the minimum population size.
    Trends in pup counts from 1975 through 2008 have been assessed for 
four rookeries in southern California and for haul-outs in central and 
northern California. During this time period counts of pups increased 
at an annual rate of 5.4 percent, excluding six El Ni[ntilde]o years 
when pup production declined dramatically before quickly rebounding 
(Carretta et al., 2011). The maximum population growth rate was 9.2 
percent when pup counts from the El Ni[ntilde]o years were removed. 
However, the apparent growth rate from the population trajectory 
underestimates the intrinsic growth rate because it does not consider 
human-caused mortality occurring during the time series; the default 
maximum net productivity rate for pinnipeds (12 percent per year) is 
considered appropriate for California sea lions (Carretta et al., 
2011).
    Historic exploitation of California sea lions include harvest for 
food by Native Americans in pre-historic times and for oil and hides in 
the mid-1800s, as well as exploitation for a variety of reasons more 
recently (Carretta et al., 2011). There are few historical records to 
document the effects of such exploitation on sea lion abundance (Lowry 
et al., 1992). Data from 2003-09 indicate that a minimum of 337 (CV = 
0.56) California sea lions are killed annually in commercial fisheries. 
In addition, a summary of stranding database records for 2005-09 shows 
an annual average of 65 such events, which is likely a gross 
underestimate because most carcasses are not recovered. California sea 
lions may also be removed because of predation on endangered salmonids 
(17 per year, 2008-10) or incidentally captured during scientific 
research (3 per year, 2005-09) (Carretta et al., 2011). Sea lion 
mortality has also been linked to the algal-produced neurotoxin domoic 
acid (Scholin et al., 2000). There is currently an Unusual Mortality 
Event (UME) declaration in effect for California sea lions. Future 
mortality may be expected to occur, due to the sporadic occurrence of 
such harmful algal blooms. Beginning in January 2013, elevated 
strandings of California sea lion pups have been observed in Southern 
California, with live sea lion strandings nearly three times higher 
than the historical average. The causes of this UME are under 
investigation (https://www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm; accessed April 10, 2013).
    An estimated 3,000 to 5,000 California sea lions migrate northward 
along the coast to central and northern California, Oregon, Washington, 
and Vancouver Island during the non-breeding season from September to 
May (Jeffries et al., 2000) and return south the following spring 
(Mate, 1975; Bonnell et al., 1983). Peak numbers of up to 1,000 
California sea lions occur in Puget Sound (including Hood Canal) during 
this time period (Jeffries et al., 2000).
    California sea lions are present in Hood Canal during much of the 
year with the exception of mid-June through August, and occur regularly 
at NBKB, as observed during Navy waterfront surveys conducted from 
April 2008 through June 2010 (Navy, 2010). They are known to utilize a 
diversity of man-made structures for hauling out (Riedman, 1990) and, 
although there are no regular California sea lion haul-outs known 
within the Hood Canal (Jeffries et al., 2000), they are frequently 
observed hauled out at several opportune areas at NBKB (e.g., 
submarines, floating security fence, barges). As many as 81 California 
sea lions have been observed hauled out on a single day at NBKB (Agness 
and Tannenbaum, 2009a; Tannenbaum et al., 2009a; Navy, 2011). All 
documented instances of California sea lions hauling out at NBKB have 
been on submarines docked at Delta Pier, approximately 0.85 mi north of 
Service Pier, and on pontoons of the security fence. California sea 
lions have also been observed swimming near the Explosives Handling 
Wharf on several occasions, approximately 1.85 mi north of Service Pier 
(Tannenbaum et al. 2009; Navy 2010), and likely forage in both 
nearshore and inland marine deeper water habitats in the vicinity.

Killer Whale

    Killer whales are one of the most cosmopolitan marine mammals, 
found in all oceans with no apparent restrictions on temperature or 
depth, although they do occur at higher densities in colder, more 
productive waters at high latitudes and are more common in nearshore 
waters (Leatherwood and Dahlheim, 1978; Forney and Wade, 2006; Allen 
and Angliss, 2011). Killer whales are found throughout the North 
Pacific, including the entire Alaska coast, in British Columbia and 
Washington inland waterways, and along the outer coasts of Washington, 
Oregon, and California. On the basis of differences in morphology, 
ecology, genetics, and behavior, populations of killer whales have 
largely been classified as ``resident'', ``transient'', or ``offshore'' 
(e.g.,

[[Page 29716]]

Dahlheim et al., 2008). Several studies have also provided evidence 
that these ecotypes are genetically distinct, and that further genetic 
differentiation is present between subpopulations of the resident and 
transient ecotypes (e.g., Barrett-Lennard, 2000). The taxonomy of 
killer whales is unresolved, with expert opinion generally following 
one of two lines: killer whales are either (1) a single highly variable 
species, with locally differentiated ecotypes representing recently 
evolved and relatively ephemeral forms not deserving species status, or 
(2) multiple species, supported by the congruence of several lines of 
evidence for the distinctness of sympatrically occurring forms (Krahn 
et al., 2004). Resident and transient whales are currently considered 
to be unnamed subspecies (Committee on Taxonomy, 2011).
    The resident and transient populations have been divided further 
into different subpopulations on the basis of genetic analyses, 
distribution, and other factors. Recognized stocks in the North Pacific 
include Alaska Residents, Northern Residents, Southern Residents, Gulf 
of Alaska, Aleutian Islands, and Bering Sea Transients, and West Coast 
Transients, along with a single offshore stock. West Coast Transient 
killer whales, which occur from California through southeastern Alaska, 
are the only type expected to potentially occur in the project area.
    West Coast Transient killer whales are not protected under the ESA 
or listed as depleted under the MMPA. The estimated annual level of 
human-caused mortality (0) does not exceed the calculated PBR (3.5); 
therefore, West Coast Transient killer whales are not considered a 
strategic stock under the MMPA. It is thought that the stock grew 
rapidly from the mid-1970s to mid-1990s as a result of a combination of 
high birth rate, survival, as well as greater immigration of animals 
into the nearshore study area (DFO, 2009). The rapid growth of the 
population during this period coincided with a dramatic increase in the 
abundance of the whales' primary prey, harbor seals, in nearshore 
waters. Population growth began slowing in the mid-1990s and has 
continued to slow in recent years (DFO, 2009). Population trends and 
status of this stock relative to its OSP level are currently unknown, 
as is the actual maximum productivity rate. Analyses in DFO (2009) 
estimated a rate of increase of about six percent per year from 1975 to 
2006, but this included recruitment of non-calf whales into the 
population. The default maximum net growth rate for cetaceans (4 
percent) is considered appropriate pending additional information 
(Carretta et al., 2011).
    The West Coast transient stock is a trans-boundary stock, with 
minimum counts for the population of transient killer whales coming 
from various photographic datasets. Combining these counts of cataloged 
transient whales gives an abundance estimate of 354 individuals for the 
West Coast transient stock (Allen and Angliss, 2011). Although this 
direct count of individually identifiable animals does not necessarily 
represent the number of live animals, it is considered a conservative 
minimum estimate (Allen and Angliss, 2011). However, the number in 
Washington waters at any one time is probably fewer than twenty 
individuals (Wiles, 2004). The West Coast transient killer whale stock 
is not designated as depleted under the MMPA or listed under the ESA. 
The estimated annual level of human-caused mortality and serious injury 
does not exceed the PBR. Therefore, the West Coast Transient stock of 
killer whales is not classified as a strategic stock.
    The estimated minimum mortality rate incidental to U.S. commercial 
fisheries is zero animals per year (Allen and Angliss, 2011). However, 
this could represent an underestimate as regards total fisheries-
related mortality due to a lack of data concerning marine mammal 
interactions in Canadian commercial fisheries known to have potential 
for interaction with killer whales. Any such interactions are thought 
to be few in number (Allen and Angliss, 2011). Other mortality, as a 
result of shootings or ship strikes, has been of concern in the past. 
However, no ship strikes have been reported for this stock, and 
shooting of transients is thought to be minimal because their diet is 
based on marine mammals rather than fish. There are no reports of a 
subsistence harvest of killer whales in Alaska or Canada.
    Transient occurrence in inland waters appears to peak during August 
and September which is the peak time for harbor seal pupping, weaning, 
and post-weaning (Baird and Dill, 1995). In 2003 and 2005, small groups 
of transient killer whales (eleven and six individuals, respectively) 
were present in Hood Canal for significant periods of time (59 and 172 
days, respectively) between the months of January and July. While 
present, the whales preyed on harbor seals in the subtidal zone of the 
nearshore marine and inland marine deeper water habitats (London, 
2006).

Dall's Porpoise

    Dall's porpoises are endemic to temperate waters of the North 
Pacific, typically in deeper waters between 30-62[deg] N, and are found 
from northern Baja California to the northern Bering Sea. Stock 
structure for Dall's porpoises is not well known; because there are no 
cooperative management agreements with Mexico or Canada for fisheries 
which may take this species, Dall's porpoises are divided for 
management purposes into two discrete, noncontiguous areas: (1) waters 
off California, Oregon, and Washington, and (2) Alaskan waters 
(Carretta et al., 2011). Only individuals from the CA/OR/WA stock may 
occur within the project area.
    Dall's porpoises are not protected under the ESA or listed as 
depleted under the MMPA. The minimum estimate of annual human-caused 
mortality (0.4) is substantially less than the calculated PBR (257); 
therefore, Dall's porpoises are not considered a strategic stock under 
the MMPA. The status of Dall's porpoises in California, Oregon and 
Washington relative to OSP is not known (Carretta et al., 2011).
    Dall's porpoise distribution on the U.S. west coast is highly 
variable between years and appears to be affected by oceanographic 
conditions (Forney and Barlow, 1998); animals may spend more or less 
time outside of U.S. waters as oceanographic conditions change. 
Therefore, a multi-year average of 2005 and 2008 summer/autumn vessel-
based line transect surveys of California, Oregon, and Washington 
waters was used to estimate a best abundance of 42,000 (CV = 0.33) 
animals (Forney, 2007; Barlow, 2010). The minimum population is 
considered to be 32,106 animals. Dall's porpoises also occur in the 
inland waters of Washington, but the most recent estimate was obtained 
in 1996 (900 animals; CV = 0.40; Calambokidis et al., 1997) and is not 
included in the overall estimate of abundance for this stock. Because 
distribution and abundance of this stock is so variable, population 
trends are not available (Carretta et al., 2011). No information is 
available regarding productivity rates, and the default maximum net 
growth rate for cetaceans (4 percent) is considered appropriate 
(Carretta et al., 2011).
    Data from 2002-08, from all fisheries for which mortality data are 
available, indicate that a minimum of 0.4 animals are killed per year 
(Carretta et al., 2011). Species-specific information is not available 
for Mexican fisheries, which could be an additional source of mortality 
for animals beyond the stock boundaries delineated for management 
purposes. No other sources of human-caused mortality are known.
    In Washington, Dall's porpoises are most abundant in offshore 
waters where

[[Page 29717]]

they are year-round residents, although interannual distribution is 
highly variable (Green et al., 1992). Dall's porpoises are observed 
throughout the year in the Puget Sound north of Seattle, are seen 
occasionally in southern Puget Sound, and may also occasionally occur 
in Hood Canal. However, only a single Dall's porpoise has been observed 
at NBKB, in deeper water during a 2008 summer survey (Tannenbaum et 
al., 2009a).

Harbor Porpoise

    Harbor porpoises are found primarily in inshore and relatively 
shallow coastal waters (< 100 m) from Point Barrow to Point Conception. 
Various genetic analyses and investigation of pollutant loads indicate 
a low mixing rate for harbor porpoise along the west coast of North 
America and likely fine-scale geographic structure along an almost 
continuous distribution from California to Alaska (e.g., Calambokidis 
and Barlow, 1991; Osmek et al., 1994; Chivers et al., 2002, 2007). 
However, stock boundaries are difficult to draw because any rigid line 
is generally arbitrary from a biological perspective. On the basis of 
genetic data and density discontinuities identified from aerial 
surveys, eight stocks have been identified in the eastern North 
Pacific, including northern Oregon/Washington coastal and inland 
Washington stocks (Carretta et al., 2011). The Washington inland waters 
stock includes individuals found east of Cape Flattery and is the only 
stock that may occur in the project area.
    Harbor porpoises of Washington inland waters are not protected 
under the ESA or listed as depleted under the MMPA. Because there is no 
current abundance estimate for this stock, there is no current estimate 
of PBR. However, because annual human-caused mortality (2.6) is less 
than the previously calculated PBR (63) the stock is not considered 
strategic under the MMPA. The status of harbor porpoises in Washington 
inland waters relative to OSP is not known (Carretta et al., 2011).
    The best estimate of abundance for this stock is derived from 
aerial surveys of the inland waters of Washington and southern British 
Columbia conducted during August of 2002 and 2003. When corrected for 
availability and perception bias, the average of the 2002-03 estimates 
of abundance for U.S. waters resulted in an estimated abundance for the 
Washington Inland Waters stock of harbor porpoise of 10,682 (CV = 0.38) 
animals (Laake et al., 1997; Carretta et al., 2011), with a minimum 
population estimate of 7,841 animals. Because the estimate is greater 
than eight years old, NMFS does not consider it current. However, it 
does represent the best available information regarding stock 
abundance.
    Although long-term harbor porpoise sightings in southern Puget 
Sound declined from the 1940s through the 1990s, sightings and 
strandings have increased in Puget Sound and northern Hood Canal in 
recent years and harbor porpoise are now considered to regularly occur 
year-round in these waters (Carretta et al., 2011). Reasons for the 
apparent decline, as well as the apparent rebound, are unknown. Recent 
observations may represent a return to historical conditions, when 
harbor porpoises were considered one of the most common cetaceans in 
Puget Sound (Scheffer and Slipp, 1948). No information regarding 
productivity is available for this stock and NMFS considers the default 
maximum net productivity rate for cetaceans (4 percent) to be 
appropriate.
    Data from 2005-09 indicate that a minimum of 2.2 Washington inland 
waters harbor seals are killed annually in U.S. commercial fisheries 
(Carretta et al., 2011). Animals captured in waters east of Cape 
Flattery are assumed to belong to this stock. This estimate is 
considered a minimum because the Washington Puget Sound Region salmon 
set/drift gillnet fishery has not been observed since 1994, and because 
of a lack of knowledge about the extent to which harbor porpoise from 
U.S. waters frequent the waters of British Columbia and are, therefore, 
subject to fishery-related mortality. However, harbor porpoise takes in 
the salmon drift gillnet fishery are unlikely to have increased since 
the fishery was last observed, when few interactions were recorded, due 
to reductions in the number of participating vessels and available 
fishing time. Fishing effort and catch have declined throughout all 
salmon fisheries in the region due to management efforts to recover 
ESA-listed salmonids (Carretta et al., 2011). In addition, an estimated 
0.4 animals per year are killed by non-fishery human causes (e.g., ship 
strike, entanglement). In 2006, a UME was declared for harbor porpoises 
throughout Oregon and Washington, and a total of 114 strandings were 
reported in 2006-07. The cause of the UME has not been determined and 
several factors, including contaminants, genetics, and environmental 
conditions, are still being investigated (Carretta et al., 2011).
    Prior to recent construction projects conducted by the Navy at 
NBKB, harbor porpoises were considered to have only occasional 
occurrence in the project area. A single harbor porpoise had been 
sighted in deeper water at NBKB during 2010 field observations 
(Tannenbaum et al., 2011). However, while implementing monitoring plans 
for work conducted from July-October, 2011, the Navy recorded multiple 
sightings of harbor porpoise in the deeper waters of the project area 
(HDR, Inc., 2012). Following these sightings, the Navy conducted 
dedicated line transect surveys, recording multiple additional 
sightings of harbor porpoise, and have revised local density estimates 
accordingly.

Potential Effects of the Specified Activity on Marine Mammals

    We have determined that pile driving, as outlined in the project 
description, has the potential to result in behavioral harassment of 
marine mammals present in the project area. Pinnipeds spend much of 
their time in the water with heads held above the surface and therefore 
are not subject to underwater noise to the same degree as cetaceans 
(although they are correspondingly more susceptible to exposure to 
airborne sound). For purposes of this assessment, however, pinnipeds 
are conservatively assumed to be available to be exposed to underwater 
sound 100 percent of the time that they are in the water.

Marine Mammal Hearing

    The primary effect on marine mammals anticipated from the specified 
activities would result from exposure of animals to underwater sound. 
Exposure to sound can affect marine mammal hearing. When considering 
the influence of various kinds of sound on the marine environment, it 
is necessary to understand that different kinds of marine life are 
sensitive to different frequencies of sound. Based on available 
behavioral data, audiograms derived using auditory evoked potential 
techniques, anatomical modeling, and other data, Southall et al. (2007) 
designate functional hearing groups for marine mammals and estimate the 
lower and upper frequencies of functional hearing of the groups. The 
functional groups and the associated frequencies are indicated below 
(though animals are less sensitive to sounds at the outer edge of their 
functional range and most sensitive to sounds of frequencies within a 
smaller range somewhere in the middle of their functional hearing 
range):
     Low frequency cetaceans (thirteen species of mysticetes): 
functional hearing is estimated to occur between approximately 7 Hz and 
22 kHz;
     Mid-frequency cetaceans (32 species of dolphins, six 
species of larger

[[Page 29718]]

toothed whales, and nineteen species of beaked and bottlenose whales): 
functional hearing is estimated to occur between approximately 150 Hz 
and 160 kHz;
     High frequency cetaceans (six species of true porpoises, 
four species of river dolphins, two members of the genus Kogia, and 
four dolphin species of the genus Cephalorhynchus): functional hearing 
is estimated to occur between approximately 200 Hz and 180 kHz; and
     Pinnipeds in water: functional hearing is estimated to 
occur between approximately 75 Hz and 75 kHz, with the greatest 
sensitivity between approximately 700 Hz and 20 kHz.
    Three pinniped and three cetacean species could potentially occur 
in the proposed project area during the project timeframe. Of the 
cetacean species that may occur in the project area, the killer whale 
is classified as a mid-frequency cetacean and the two porpoises are 
classified as high-frequency cetaceans (Southall et al., 2007).

Underwater Sound Effects

    Potential Effects of Pile Driving Sound--The effects of sounds from 
pile driving might result in one or more of the following: temporary or 
permanent hearing impairment, non-auditory physical or physiological 
effects, behavioral disturbance, and masking (Richardson et al., 1995; 
Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007). The 
effects of pile driving on marine mammals are dependent on several 
factors, including the size, type, and depth of the animal; the depth, 
intensity, and duration of the pile driving sound; the depth of the 
water column; the substrate of the habitat; the standoff distance 
between the pile and the animal; and the sound propagation properties 
of the environment. Impacts to marine mammals from pile driving 
activities are expected to result primarily from acoustic pathways. As 
such, the degree of effect is intrinsically related to the received 
level and duration of the sound exposure, which are in turn influenced 
by the distance between the animal and the source. The further away 
from the source, the less intense the exposure should be. The substrate 
and depth of the habitat affect the sound propagation properties of the 
environment. Shallow environments are typically more structurally 
complex, which leads to rapid sound attenuation. In addition, 
substrates that are soft (e.g., sand) would absorb or attenuate the 
sound more readily than hard substrates (e.g., rock) which may reflect 
the acoustic wave. Soft porous substrates would also likely require 
less time to drive the pile, and possibly less forceful equipment, 
which would ultimately decrease the intensity of the acoustic source.
    In the absence of mitigation, impacts to marine species would be 
expected to result from physiological and behavioral responses to both 
the type and strength of the acoustic signature (Viada et al., 2008). 
The type and severity of behavioral impacts are more difficult to 
define due to limited studies addressing the behavioral effects of 
impulsive sounds on marine mammals. Potential effects from impulsive 
sound sources can range in severity, ranging from effects such as 
behavioral disturbance, tactile perception, physical discomfort, slight 
injury of the internal organs and the auditory system, to mortality 
(Yelverton et al., 1973).
    Hearing Impairment and Other Physical Effects--Marine mammals 
exposed to high intensity sound repeatedly or for prolonged periods can 
experience hearing threshold shift (TS), which is the loss of hearing 
sensitivity at certain frequency ranges (Kastak et al., 1999; Schlundt 
et al., 2000; Finneran et al., 2002, 2005). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not recoverable, or 
temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Marine mammals depend on 
acoustic cues for vital biological functions, (e.g., orientation, 
communication, finding prey, avoiding predators); thus, TTS may result 
in reduced fitness in survival and reproduction. However, this depends 
on the frequency and duration of TTS, as well as the biological context 
in which it occurs. TTS of limited duration, occurring in a frequency 
range that does not coincide with that used for recognition of 
important acoustic cues, would have little to no effect on an animal's 
fitness. Repeated sound exposure that leads to TTS could cause PTS. 
PTS, in the unlikely event that it occurred, would constitute injury, 
but TTS is not considered injury (Southall et al., 2007). It is 
unlikely that the project would result in any cases of temporary or 
especially permanent hearing impairment or any significant non-auditory 
physical or physiological effects for reasons discussed later in this 
document. Some behavioral disturbance is expected, but it is likely 
that this would be localized and short-term because of the short 
project duration.
    Several aspects of the planned monitoring and mitigation measures 
for this project (see the ``Proposed Mitigation'' and ``Proposed 
Monitoring and Reporting'' sections later in this document) are 
designed to detect marine mammals occurring near the pile driving to 
avoid exposing them to sound pulses that might, in theory, cause 
hearing impairment. In addition, many cetaceans are likely to show some 
avoidance of the area where received levels of pile driving sound are 
high enough that hearing impairment could potentially occur. In those 
cases, the avoidance responses of the animals themselves would reduce 
or (most likely) avoid any possibility of hearing impairment. Non-
auditory physical effects may also occur in marine mammals exposed to 
strong underwater pulsed sound. It is especially unlikely that any 
effects of these types would occur during the present project given the 
brief duration of exposure for any given individual and the planned 
monitoring and mitigation measures. The following subsections discuss 
in somewhat more detail the possibilities of TTS, PTS, and non-auditory 
physical effects.
    Temporary Threshold Shift--TTS is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing TTS, the hearing threshold rises, and a sound 
must be stronger in order to be heard. In terrestrial mammals, TTS can 
last from minutes or hours to days (in cases of strong TTS). For sound 
exposures at or somewhat above the TTS threshold, hearing sensitivity 
in both terrestrial and marine mammals recovers rapidly after exposure 
to the sound ends. Few data on sound levels and durations necessary to 
elicit mild TTS have been obtained for marine mammals, and none of the 
published data concern TTS elicited by exposure to multiple pulses of 
sound. Available data on TTS in marine mammals are summarized in 
Southall et al. (2007).
    Given the available data, the received level of a single pulse 
(with no frequency weighting) might need to be approximately 186 dB re 
1 [mu]Pa\2\-s (i.e., 186 dB sound exposure level [SEL] or approximately 
221-226 dB pk-pk) in order to produce brief, mild TTS. Exposure to 
several strong pulses that each have received levels near 190 dB re 1 
[mu]Pa rms (175-180 dB SEL) might result in cumulative exposure of 
approximately 186 dB SEL and thus slight TTS in a small odontocete, 
assuming the TTS threshold is (to a first approximation) a function of 
the total received pulse energy. Levels greater than or equal to 190 dB 
re 1 [mu]Pa rms are expected to be restricted to radii no more than 5 m 
(16 ft) from the pile driving. For an odontocete closer to the surface, 
the maximum radius with

[[Page 29719]]

greater than or equal to 190 dB re 1 [mu]Pa rms would be smaller.
    The above TTS information for odontocetes is derived from studies 
on the bottlenose dolphin (Tursiops truncatus) and beluga whale 
(Delphinapterus leucas). There is no published TTS information for 
other species of cetaceans. However, preliminary evidence from a harbor 
porpoise exposed to pulsed sound suggests that its TTS threshold may 
have been lower (Lucke et al., 2009). To avoid the potential for 
injury, NMFS has determined that cetaceans should not be exposed to 
pulsed underwater sound at received levels exceeding 180 dB re 1 [mu]Pa 
rms. As summarized above, data that are now available imply that TTS is 
unlikely to occur unless odontocetes are exposed to pile driving pulses 
stronger than 180 dB re 1 [mu]Pa rms.
    Permanent Threshold Shift--When PTS occurs, there is physical 
damage to the sound receptors in the ear. In severe cases, there can be 
total or partial deafness, while in other cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985). There is no specific evidence that exposure to pulses of sound 
can cause PTS in any marine mammal. However, given the possibility that 
mammals close to pile driving activity might incur TTS, there has been 
further speculation about the possibility that some individuals 
occurring very close to pile driving might incur PTS. Single or 
occasional occurrences of mild TTS are not indicative of permanent 
auditory damage, but repeated or (in some cases) single exposures to a 
level well above that causing TTS onset might elicit PTS.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several decibels above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time. Based on data from 
terrestrial mammals, a precautionary assumption is that the PTS 
threshold for impulse sounds (such as pile driving pulses as received 
close to the source) is at least 6 dB higher than the TTS threshold on 
a peak-pressure basis and probably greater than 6 dB (Southall et al., 
2007). On an SEL basis, Southall et al. (2007) estimated that received 
levels would need to exceed the TTS threshold by at least 15 dB for 
there to be risk of PTS. Thus, for cetaceans, Southall et al. (2007) 
estimate that the PTS threshold might be an M-weighted SEL (for the 
sequence of received pulses) of approximately 198 dB re 1 [mu]Pa\2\-s 
(15 dB higher than the TTS threshold for an impulse). Given the higher 
level of sound necessary to cause PTS as compared with TTS, it is 
considerably less likely that PTS could occur.
    Measured source levels from impact pile driving can be as high as 
214 dB re 1 [mu]Pa at 1 m (3.3 ft). Although no marine mammals have 
been shown to experience TTS or PTS as a result of being exposed to 
pile driving activities, captive bottlenose dolphins and beluga whales 
exhibited changes in behavior when exposed to strong pulsed sounds 
(Finneran et al., 2000, 2002, 2005). The animals tolerated high 
received levels of sound before exhibiting aversive behaviors. 
Experiments on a beluga whale showed that exposure to a single watergun 
impulse at a received level of 207 kPa (30 psi) p-p, which is 
equivalent to 228 dB p-p re 1 [mu]Pa, resulted in a 7 and 6 dB TTS in 
the beluga whale at 0.4 and 30 kHz, respectively. Thresholds returned 
to within 2 dB of the pre-exposure level within four minutes of the 
exposure (Finneran et al., 2002). Although the source level of pile 
driving from one hammer strike is expected to be much lower than the 
single watergun impulse cited here, animals being exposed for a 
prolonged period to repeated hammer strikes could receive more sound 
exposure in terms of SEL than from the single watergun impulse 
(estimated at 188 dB re 1 [mu]Pa\2\-s) in the aforementioned experiment 
(Finneran et al., 2002). However, in order for marine mammals to 
experience TTS or PTS, the animals have to be close enough to be 
exposed to high intensity sound levels for a prolonged period of time. 
Based on the best scientific information available, these SPLs are far 
below the thresholds that could cause TTS or the onset of PTS.
    Non-auditory Physiological Effects--Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance effects, and other types of organ 
or tissue damage (Cox et al., 2006; Southall et al., 2007). Studies 
examining such effects are limited. In general, little is known about 
the potential for pile driving to cause auditory impairment or other 
physical effects in marine mammals. Available data suggest that such 
effects, if they occur at all, would presumably be limited to short 
distances from the sound source and to activities that extend over a 
prolonged period. The available data do not allow identification of a 
specific exposure level above which non-auditory effects can be 
expected (Southall et al., 2007) or any meaningful quantitative 
predictions of the numbers (if any) of marine mammals that might be 
affected in those ways. Marine mammals that show behavioral avoidance 
of pile driving, including some odontocetes and some pinnipeds, are 
especially unlikely to incur auditory impairment or non-auditory 
physical effects.

Disturbance Reactions

    Disturbance includes a variety of effects, including subtle changes 
in behavior, more conspicuous changes in activities, and displacement. 
Behavioral responses to sound are highly variable and context-specific 
and reactions, if any, depend on species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day, and many other factors (Richardson et al., 1995; Wartzok 
et al., 2003/2004; Southall et al., 2007).
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003/04). Animals are most likely to habituate 
to sounds that are predictable and unvarying. The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. Behavioral state may affect the type of response as well. 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; 
NRC, 2003; Wartzok et al., 2003/04).
    Controlled experiments with captive marine mammals 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 
(typically seismic guns or acoustic harassment devices, but also 
including pile driving) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Morton and 
Symonds, 2002; Thorson and Reyff, 2006; see also Gordon et al., 2004; 
Wartzok et al., 2003/04; Nowacek et al., 2007). Responses to continuous 
sound, such as vibratory pile installation, have not been documented as 
well as responses to pulsed sounds.
    With both types of pile driving, it is likely that the onset of 
pile driving could result in temporary, short term changes in an 
animal's typical behavior and/or avoidance of the affected area.

[[Page 29720]]

These behavioral changes may include (Richardson et al., 1995): 
changing durations of surfacing and dives, number of blows per 
surfacing, or moving direction and/or speed; reduced/increased vocal 
activities; changing/cessation of certain behavioral activities (such 
as socializing or feeding); visible startle response or aggressive 
behavior (such as tail/fluke slapping or jaw clapping); avoidance of 
areas where sound sources are located; and/or flight responses (e.g., 
pinnipeds flushing into water from haul-outs or rookeries). Pinnipeds 
may increase their haul-out time, possibly to avoid in-water 
disturbance (Thorson and Reyff, 2006). Since pile driving would likely 
only occur for a few hours a day, over a short period of time, it is 
unlikely to result in permanent displacement. Any potential impacts 
from pile driving activities could be experienced by individual marine 
mammals, but would not be likely to cause population level impacts, or 
affect the long-term fitness of the species.
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be expected to be biologically significant if the 
change affects growth, survival, or reproduction. Significant 
behavioral modifications that could potentially lead to effects on 
growth, survival, or reproduction include:
     Drastic changes in diving/surfacing patterns (such as 
those thought to be causing beaked whale stranding due to exposure to 
military mid-frequency tactical sonar);
     Habitat abandonment due to loss of desirable acoustic 
environment; and
     Cessation of feeding or social interaction.
    The onset of behavioral disturbance from anthropogenic sound 
depends on both external factors (characteristics of sound sources and 
their paths) and the specific characteristics of the receiving animals 
(hearing, motivation, experience, demography) and is difficult to 
predict (Southall et al., 2007).

Auditory Masking

    Natural and artificial sounds can disrupt behavior by masking, or 
interfering with, a marine mammal's ability to hear other sounds. 
Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher levels. Chronic exposure to excessive, though not high-
intensity, sound could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions. 
Masking can interfere with detection of acoustic signals such as 
communication calls, echolocation sounds, and environmental sounds 
important to marine mammals. 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. If the coincident 
(masking) sound were man-made, it could be potentially harassing if it 
disrupted hearing-related behavior. It is important to distinguish TTS 
and PTS, which persist after the sound exposure, from masking, which 
occurs during the sound exposure. Because masking (without resulting in 
TS) is not associated with abnormal physiological function, it is not 
considered a physiological effect, but rather a potential behavioral 
effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. Because sound 
generated from in-water pile driving is mostly concentrated at low 
frequency ranges, it may have less effect on high frequency 
echolocation sounds made by porpoises. However, lower frequency man-
made sounds are more likely to affect detection of communication calls 
and other potentially important natural sounds such as surf and prey 
sound. It may also affect communication signals when they occur near 
the sound band and thus reduce the communication space of animals 
(e.g., Clark et al., 2009) and cause increased stress levels (e.g., 
Foote et al., 2004; Holt et al., 2009).
    Masking has the potential to impact species at population, 
community, or even ecosystem levels, as well as at individual levels. 
Masking affects both senders and receivers of the signals and can 
potentially have long-term chronic effects on marine mammal species and 
populations. Recent research suggests that low frequency ambient sound 
levels have increased by as much as 20 dB (more than three times in 
terms of SPL) in the world's ocean from pre-industrial periods, and 
that most of these increases are from distant shipping (Hildebrand, 
2009). All anthropogenic sound sources, such as those from vessel 
traffic, pile driving, and dredging activities, contribute to the 
elevated ambient sound levels, thus intensifying masking. However, the 
sum of sound from the proposed activities is confined in an area of 
inland waters (Hood Canal) that is bounded by landmass; therefore, the 
sound generated is not expected to contribute to increased ocean 
ambient sound.
    The most intense underwater sounds in the proposed action are those 
produced by impact pile driving. Given that the energy distribution of 
pile driving covers a broad frequency spectrum, sound from these 
sources would likely be within the audible range of marine mammals 
present in the project area. Impact pile driving activity is relatively 
short-term, with rapid pulses occurring for approximately fifteen 
minutes per pile. The probability for impact pile driving resulting 
from this proposed action masking acoustic signals important to the 
behavior and survival of marine mammal species is likely to be 
negligible. Vibratory pile driving is also relatively short-term, with 
rapid oscillations occurring for approximately one and a half hours per 
pile. It is possible that vibratory pile driving resulting from this 
proposed action may mask acoustic signals important to the behavior and 
survival of marine mammal species, but the short-term duration and 
limited affected area would result in insignificant impacts from 
masking. Any masking event that could possibly rise to Level B 
harassment under the MMPA would occur concurrently within the zones of 
behavioral harassment already estimated for vibratory and impact pile 
driving, and which have already been taken into account in the exposure 
analysis.

Airborne Sound Effects

    Marine mammals that occur in the project area could be exposed to 
airborne sounds associated with pile driving that have the potential to 
cause harassment, depending on their distance from pile driving 
activities. Airborne pile driving sound would have less impact on 
cetaceans than pinnipeds because sound from atmospheric sources does 
not transmit well underwater (Richardson et al., 1995); thus, airborne 
sound would only be an issue for hauled-out pinnipeds in the project 
area. 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 their habitat and 
move further from the source. Studies by Blackwell et al. (2004) and 
Moulton et al. (2005) indicate a tolerance or lack of response to 
unweighted airborne sounds as high as 112 dB peak and 96 dB rms.

[[Page 29721]]

Anticipated Effects on Habitat

    The proposed activities at NBKB would not result in permanent 
impacts to habitats used directly by marine mammals, such as haul-out 
sites, but may have potential short-term impacts to food sources such 
as forage fish and salmonids. There are no rookeries or major haul-out 
sites within 10 km, foraging hotspots, or other ocean bottom structure 
of significant biological importance to marine mammals that may be 
present in the marine waters in the vicinity of the project area. 
Therefore, the main impact issue associated with the proposed activity 
would be temporarily elevated sound levels and the associated direct 
effects on marine mammals, as discussed previously in this document. 
The most likely impact to marine mammal habitat occurs from pile 
driving effects on likely marine mammal prey (i.e., fish) near NBKB and 
minor impacts to the immediate substrate during installation and 
removal of piles during the wharf construction project.

Pile Driving Effects on Potential Prey (Fish)

    Construction activities would produce both pulsed (i.e., impact 
pile driving) and continuous (i.e., vibratory pile driving) sounds. 
Fish react to sounds which 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. Hastings and 
Popper (2005, 2009) identified several studies that suggest fish may 
relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving (or other types of continuous 
sounds) on fish, although several are based on studies in support of 
large, multiyear bridge construction projects (e.g., Scholik and Yan, 
2001, 2002; Popper and Hastings, 2009). Sound pulses at received levels 
of 160 dB re 1 [mu]Pa may cause subtle changes in fish behavior. SPLs 
of 180 dB may cause noticeable changes in behavior (Pearson et al., 
1992; Skalski et al., 1992). SPLs of sufficient strength have been 
known to cause injury to fish and fish mortality. The most likely 
impact to fish from pile driving activities at the project area would 
be temporary behavioral avoidance of the area. The duration of fish 
avoidance of this area after pile driving stops is unknown, but a rapid 
return to normal recruitment, distribution and behavior is anticipated. 
In general, impacts to marine mammal prey species are expected to be 
minor and temporary due to the short timeframe for the wharf 
construction project. However, adverse impacts may occur to a few 
species of rockfish (bocaccio [Sebastes paucispinis], yelloweye [S. 
ruberrimus] and canary [S. pinniger] rockfish) and salmon (chinook 
[Oncorhynchus tshawytscha] and summer run chum) which may still be 
present in the project area despite operating in a reduced work window 
in an attempt to avoid important fish spawning time periods. Impacts to 
these species could result from potential impacts to their eggs and 
larvae.

Pile Driving Effects on Potential Foraging Habitat

    The area likely impacted by the project is relatively small 
compared to the available habitat in the Hood Canal. Avoidance by 
potential prey (i.e., fish) of the immediate area due to the temporary 
loss of this foraging habitat is also possible. The duration of fish 
avoidance of this area after pile driving stops is unknown, but a rapid 
return to normal recruitment, distribution and behavior is anticipated. 
Any behavioral avoidance by fish of the disturbed area would still 
leave significantly large areas of fish and marine mammal foraging 
habitat in the Hood Canal and nearby vicinity.
    Given the short daily duration of sound associated with individual 
pile driving events and the relatively small areas being affected, pile 
driving activities associated with the proposed action are not likely 
to have a permanent, adverse effect on any fish habitat, or populations 
of fish species. Therefore, pile driving is not likely to have a 
permanent, adverse effect on marine mammal foraging habitat at the 
project area.

Proposed Mitigation

    In order to issue an incidental take authorization (ITA) under 
Section 101(a)(5)(D) of the MMPA, we must, where applicable, set forth 
the permissible methods of taking pursuant to such activity, and other 
means of effecting the least practicable impact on such species or 
stock and its habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance, and on the availability of 
such species or stock for taking for certain subsistence uses (where 
relevant).
    Measurements from similar pile driving events were coupled with 
practical spreading loss to estimate zones of influence (ZOIs; see 
``Estimated Take by Incidental Harassment''); these values were used to 
develop mitigation measures for pile driving activities at NBKB. The 
ZOIs effectively represent the mitigation zone that would be 
established around each pile to prevent Level A harassment to marine 
mammals, while providing estimates of the areas within which Level B 
harassment might occur. While the ZOIs vary between the different 
diameter piles and types of installation methods, the Navy is proposing 
to establish mitigation zones for the maximum ZOI for all pile driving 
conducted in support of the wharf construction project. In addition to 
the measures described later in this section, the Navy would employ the 
following standard mitigation measures:
    (a) Conduct briefings between construction supervisors and crews, 
marine mammal monitoring team, acoustical monitoring team, and Navy 
staff prior to the start of all pile driving activity, and when new 
personnel join the work, in order to explain responsibilities, 
communication procedures, marine mammal monitoring protocol, and 
operational procedures.
    (b) Comply with applicable equipment sound standards and ensure 
that all construction equipment has sound control devices no less 
effective than those provided on the original equipment.
    (c) For in-water heavy machinery work other than pile driving 
(using, e.g., standard barges, tug boats, barge-mounted excavators, or 
clamshell equipment used to place or remove material), if a marine 
mammal comes within 10 m, operations shall cease and vessels shall 
reduce speed to the minimum level required to maintain steerage and 
safe working conditions. This type of work could include the following 
activities: (1) Movement of the barge to the pile location; (2) 
positioning of the pile on the substrate via a crane (i.e., stabbing 
the pile); (3) removal of the pile from the water column/substrate via 
a crane (i.e., deadpull); or (4) the placement of sound attenuation 
devices around the piles. For these activities, monitoring would take 
place from 15 minutes prior to initiation until the action is complete.

Monitoring and Shutdown for Pile Driving

    The following measures would apply to the Navy's mitigation through 
shutdown and disturbance zones:
    Shutdown Zone--For all pile driving and removal activities, the 
Navy will establish a shutdown zone intended to contain the area in 
which SPLs equal or exceed the 180/190 dB rms acoustic injury criteria. 
The purpose of a shutdown zone is to define an area within which 
shutdown of activity would occur upon sighting of a marine mammal (or 
in anticipation of an animal

[[Page 29722]]

entering the defined area), thus preventing injury, serious injury, or 
death of marine mammals. Modeled distances for shutdown zones are shown 
in Table 5. However, during impact pile driving, the Navy would 
implement a minimum shutdown zone of 85 m radius for cetaceans and 20 m 
for pinnipeds around all pile driving activity. The modeled injury 
threshold distances are approximately 22 and 5 m, respectively, but the 
distances are increased based on in-situ recorded sound pressure levels 
during the TPP. During vibratory driving, the shutdown zone would be 10 
m distance from the source for all animals. These precautionary 
measures are intended to act conservatively in the implementation of 
the measure and further reduce any possibility of acoustic injury. In 
addition, a minimum shutdown zone of 10 m would be in place for other 
construction activities in order to prevent the possibility of physical 
interaction. These activities may include (1) The movement of the barge 
to the pile location, (2) the positioning of the pile on the substrate 
via a crane (i.e., ``stabbing'' the pile), (3) the removal of the pile 
from the water column/substrate via a crane (i.e. ``deadpull''), or (4) 
the placement of sound attenuation devices around the piles.
    Disturbance Zone--Disturbance zones are the areas in which SPLs 
equal or exceed 160 and 120 dB rms (for pulsed and non-pulsed sound, 
respectively). Disturbance zones provide utility for monitoring 
conducted for mitigation purposes (i.e., shutdown zone monitoring) by 
establishing monitoring protocols for areas adjacent to the shutdown 
zones. Monitoring of disturbance zones enables observers to be aware of 
and communicate the presence of marine mammals in the project area but 
outside the shutdown zone and thus prepare for potential shutdowns of 
activity. However, the primary purpose of disturbance zone monitoring 
is for documenting incidents of Level B harassment; disturbance zone 
monitoring is discussed in greater detail later (see ``Proposed 
Monitoring and Reporting''). Nominal radial distances for disturbance 
zones are shown in Table 5. Given the size of the disturbance zone for 
vibratory pile driving, it is impossible to guarantee that all animals 
would be observed or to make comprehensive observations of fine-scale 
behavioral reactions to sound, and only a portion of the zone (e.g., 
what may be reasonably observed by visual observers stationed within 
the WRA) would be observed. However, these are reasonable measures that 
will enable the monitoring of take from vibratory pile driving. In 
order to document observed incidences of harassment, monitors record 
all marine mammal observations, regardless of location. The observer's 
location, as well as the location of the pile being driven, is known 
from a GPS. The location of the animal is estimated as a distance from 
the observer, which is then compared to the location from the pile. If 
acoustic monitoring is being conducted for that pile, a received SPL 
may be estimated, or the received level may be estimated on the basis 
of past or subsequent acoustic monitoring. It may then be determined 
whether the animal was exposed to sound levels constituting incidental 
harassment in post-processing of observational and acoustic data, and a 
precise accounting of observed incidences of harassment created. 
Therefore, although the predicted distances to behavioral harassment 
thresholds are useful for estimating incidental harassment for purposes 
of authorizing levels of incidental take, actual take may be determined 
in part through the use of empirical data. That information may then be 
used to extrapolate observed takes to reach an approximate 
understanding of actual total takes.
    Monitoring Protocols--Monitoring would be conducted before, during, 
and after pile driving activities. In addition, observers shall record 
all incidences of marine mammal occurrence, regardless of distance from 
activity, and shall document any behavioral reactions in concert with 
distance from piles being driven. Observations made outside the 
shutdown zone will not result in shutdown; that pile segment would be 
completed without cessation, unless the animal approaches or enters the 
shutdown zone, at which point all pile driving activities would be 
halted. Monitoring will take place from 15 minutes prior to initiation 
through 15 minutes post-completion of pile driving activities. Pile 
driving activities include the time to remove a single pile or series 
of piles, as long as the time elapsed between uses of the pile driving 
equipment is no more than 30 minutes.
    The following additional measures apply to visual monitoring:
    (1) Monitoring will be conducted by qualified observers, who will 
be placed at the best vantage point(s) practicable to monitor for 
marine mammals and implement shutdown/delay procedures when applicable 
by calling for the shutdown to the hammer operator. Qualified observers 
are trained biologists, with the following minimum qualifications:
     Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target;
     Advanced education in biological science, wildlife 
management, mammalogy, or related fields (bachelor's degree or higher 
is required);
     Experience and ability to conduct field observations and 
collect data according to assigned protocols (this may include academic 
experience);
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates and times when in-water construction 
activities were suspended to avoid potential incidental injury from 
construction sound of marine mammals observed within a defined shutdown 
zone; 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.
    (2) Prior to the start of pile driving activity, the shutdown zone 
will be monitored for 15 minutes to ensure that it is clear of marine 
mammals. Pile driving will only commence once observers have declared 
the shutdown zone clear of marine mammals; animals will be allowed to 
remain in the shutdown zone (i.e., must leave of their own volition) 
and their behavior will be monitored and documented. The shutdown zone 
may only be declared clear, and pile driving started, when the entire 
shutdown zone is visible (i.e., when not obscured by dark, rain, fog, 
etc.). In addition, if such conditions should arise during impact pile 
driving that is already underway, the activity would be halted.
    (3) If a marine mammal approaches or enters the shutdown zone 
during the course of pile driving operations, activity will be halted 
and delayed until either the animal has voluntarily left and been 
visually confirmed beyond the shutdown zone or 15 minutes have passed 
without re-detection of the animal. Monitoring will be conducted

[[Page 29723]]

throughout the time required to drive a pile.

Sound Attenuation Devices

    Bubble curtains shall be used during all impact pile driving. The 
device will distribute air bubbles around 100 percent of the piling 
perimeter for the full depth of the water column, and the lowest bubble 
ring shall be in contact with the mudline for the full circumference of 
the ring. Testing of the device by comparing attenuated and 
unattenuated strikes is not possible because of requirements in place 
to protect marbled murrelets (an ESA-listed bird species under the 
jurisdiction of the USFWS). However, in order to avoid loss of 
attenuation from design and implementation errors in the absence of 
such testing, a performance test of the device shall be conducted prior 
to initial use. The performance test shall confirm the calculated 
pressures and flow rates at each manifold ring. In addition, the 
contractor shall also train personnel in the proper balancing of air 
flow to the bubblers and shall submit an inspection/performance report 
to the Navy within 72 hours following the performance test.

Timing Restrictions

    In Hood Canal, designated exist timing restrictions for pile 
driving activities to avoid in-water work when salmonids and other 
spawning forage fish are likely to be present. The in-water work window 
is July 16-February 15. The initial months (July to September) of the 
timing window overlap with times when Steller sea lions are not 
expected to be present within the project area. Until July 16, impact 
pile driving will only occur starting two hours after sunrise and 
ending two hours before sunset due to marbled murrelet nesting season. 
After July 16, in-water construction activities will occur during 
daylight hours (sunrise to sunset).

Soft Start

    The use of a soft-start procedure is believed to provide additional 
protection to marine mammals by warning or providing a chance to leave 
the area prior to the hammer operating at full capacity, and typically 
involves a requirement to initiate sound from vibratory hammers for 
fifteen seconds at reduced energy followed by a 30-second waiting 
period. This procedure is repeated two additional times. However, 
implementation of soft start for vibratory pile driving during previous 
pile driving work at NBKB has led to equipment failure and serious 
human safety concerns. Project staff have reported that, during power 
down from the soft start, the energy from the hammer is transferred to 
the crane boom and block via the load fall cables and rigging resulting 
in unexpected damage to both the crane block and crane boom. This 
differs from what occurs when the hammer is powered down after a pile 
is driven to refusal in that the rigging and load fall cables are able 
to be slacked prior to powering down the hammer, and the vibrations are 
transferred into the substrate via the pile rather than into the 
equipment via the rigging. One dangerous incident of equipment failure 
has already occurred, with a portion of the equipment shearing from the 
crane and falling to the deck. Subsequently, the crane manufacturer has 
inspected the crane booms and discovered structural fatigue in the boom 
lacing and main structural components, which will ultimately result in 
a collapse of the crane boom. All cranes were new at the beginning of 
the job. In addition, the vibratory hammer manufacturer has attempted 
to install dampers to mitigate the problem, without success. As a 
result of this dangerous situation, the measure will not be required 
for this project. This information was provided to us after the Navy 
submitted their request for authorization and is not reflected in that 
document.
    For impact driving, soft start will be required, and contractors 
will provide an initial set of three strikes from the impact hammer at 
40 percent energy, followed by a 30-second waiting period, then two 
subsequent three strike sets.
    We have carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that we prescribe the means of effecting the least practicable 
impact on the affected marine mammal species and stocks and their 
habitat. Our evaluation of potential measures included consideration of 
the following factors in relation to one another: (1) The manner in 
which, and the degree to which, the successful implementation of the 
measure is expected to minimize adverse impacts to marine mammals; (2) 
the proven or likely efficacy of the specific measure to minimize 
adverse impacts as planned; and (3) the practicability of the measure 
for applicant implementation, including consideration of personnel 
safety, and practicality of implementation.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered, we have preliminarily determined 
that the proposed mitigation measures provide the means of effecting 
the least practicable impact on marine mammal 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 ITA for an activity, section 101(a)(5)(D) of 
the MMPA states that we must, where applicable, 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 ITAs must include the suggested means of 
accomplishing the necessary monitoring and reporting that would result 
in increased knowledge of the species and of the level of taking or 
impacts on populations of marine mammals that are expected to be 
present in the proposed action area.

Visual Marine Mammal Observations

    The Navy will collect sighting data and behavioral responses to 
construction for marine mammal species observed in the region of 
activity during the period of activity. All observers will be trained 
in marine mammal identification and behaviors and are required to have 
no other construction-related tasks while conducting monitoring. The 
Navy will monitor the shutdown zone and disturbance zone before, 
during, and after pile driving, with observers located at the best 
practicable vantage points. Based on our requirements, the Marine 
Mammal Monitoring Plan would implement the following procedures for 
pile driving:
     MMOs would be located at the best vantage point(s) in 
order to properly see the entire shutdown zone and as much of the 
disturbance zone as possible.
     During all observation periods, observers will use 
binoculars and the naked eye to search continuously for marine mammals.
     If the shutdown zones are obscured by fog or poor lighting 
conditions, pile driving at that location will not be initiated until 
that zone is visible. Should such conditions arise while impact driving 
is underway, the activity would be halted.
     The shutdown and disturbance zones around the pile will be 
monitored for the presence of marine mammals before, during, and after 
any pile driving or removal activity.
    Individuals implementing the monitoring protocol will assess its 
effectiveness using an adaptive approach. Monitoring biologists will 
use their best professional judgment throughout implementation and seek 
improvements to these methods when

[[Page 29724]]

deemed appropriate. Any modifications to protocol will be coordinated 
between NMFS and the Navy.

Data Collection

    We require that observers use approved data forms. Among other 
pieces of information, the Navy will record detailed information about 
any implementation of shutdowns, including the distance of animals to 
the pile and description of specific actions that ensued and resulting 
behavior of the animal, if any. In addition, the Navy will attempt to 
distinguish between the number of individual animals taken and the 
number of incidences of take. We require that, at a minimum, the 
following information be collected on the sighting forms:
     Date and time that monitored activity begins or ends;
     Construction activities occurring during each observation 
period;
     Weather parameters (e.g., percent cover, visibility);
     Water conditions (e.g., sea state, tide state);
     Species, numbers, and, if possible, sex and age class of 
marine mammals;
     Description of any observable marine mammal behavior 
patterns, including bearing and direction of travel, and if possible, 
the correlation to SPLs;
     Distance from pile driving activities to marine mammals 
and distance from the marine mammals to the observation point;
     Locations of all marine mammal observations; and
     Other human activity in the area.

Reporting

    A draft report would be submitted to NMFS within 90 calendar days 
of the completion of the in-water work window. The report will include 
marine mammal observations pre-activity, during-activity, and post-
activity during pile driving days, and will also provide descriptions 
of any problems encountered in deploying sound attenuating devices, any 
adverse responses to construction activities by marine mammals and a 
complete description of all mitigation shutdowns and the results of 
those actions and a refined take estimate based on the number of marine 
mammals observed during the course of construction. A final report 
would be prepared and submitted within 30 days following resolution of 
comments on the draft report.

Estimated Take by Incidental Harassment

    With respect to the activities described here, the MMPA defines 
``harassment'' as: ``any act of pursuit, torment, or annoyance which 
(i) has the potential to injure a marine mammal or marine mammal stock 
in the wild [Level A harassment]; or (ii) has the potential to disturb 
a marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering [Level 
B harassment].''
    All anticipated takes would be by Level B harassment, involving 
temporary changes in behavior. The proposed mitigation and monitoring 
measures are expected to minimize the possibility of injurious or 
lethal takes such that take by Level A harassment, serious injury or 
mortality is considered discountable. However, as noted earlier, it is 
unlikely that injurious or lethal takes would occur even in the absence 
of the planned mitigation and monitoring measures.
    If a marine mammal responds to an underwater sound by changing its 
behavior (e.g., through relatively minor changes in locomotion 
direction/speed or vocalization behavior), the response may or may not 
constitute taking at the individual level, and is unlikely to affect 
the stock or the species as a whole. However, if a sound source 
displaces marine mammals from an important feeding or breeding area for 
a prolonged period, impacts on animals or on the stock or species could 
potentially be significant (Lusseau and Bejder, 2007; Weilgart, 2007). 
Given the many uncertainties in predicting the quantity and types of 
impacts of sound on marine mammals, it is common practice to estimate 
how many animals are likely to be present within a particular distance 
of a given activity, or exposed to a particular level of sound. This 
practice potentially overestimates the numbers of marine mammals 
actually subject to disturbance that would correctly be considered a 
take under the MMPA. For example, during the past ten years, transient 
killer whales have been observed within the project area twice. On the 
basis of that information, an estimated amount of potential takes for 
killer whales is presented here. However, while a pod of killer whales 
could potentially visit again during the project timeframe, and thus be 
taken, it is more likely that they would not. Although incidental take 
of killer whales and Dall's porpoises was authorized for 2011-12 
activities at NBKB on the basis of past observations of these species, 
no such takes were recorded and no individuals of these species were 
observed. Similarly, estimated actual take levels (observed takes 
extrapolated to the remainder of unobserved but ensonified area) were 
significantly less than authorized levels of take for the remaining 
species.
    The project area is not believed to be particularly important 
habitat for marine mammals, nor is it considered an area frequented by 
marine mammals, although harbor seals are year-round residents of Hood 
Canal and sea lions are known to haul-out on submarines and other man-
made objects at the NBKB waterfront (although typically at a distance 
of a mile or greater from the project site). Therefore, behavioral 
disturbances that could result from anthropogenic sound associated with 
these activities are expected to affect relatively small numbers of 
individual marine mammals, although those effects could be recurring 
over the life of the project if the same individuals remain in the 
project vicinity.
    The Navy has requested authorization for the incidental taking of 
small numbers of Steller sea lions, California sea lions, harbor seals, 
transient killer whales, Dall's porpoises, and harbor porpoises in the 
Hood Canal that may result from pile driving during construction 
activities associated with the wharf construction project described 
previously in this document. The takes requested are expected to have 
no more than a minor effect on individual animals and no effect at the 
population level for these species. Any effects experienced by 
individual marine mammals are anticipated to be limited to short-term 
disturbance of normal behavior or temporary displacement of animals 
near the source of the sound.

Marine Mammal Densities

    The Navy is in the process of developing, with input from regional 
marine mammal experts, estimates of marine mammal densities in 
Washington inland waters for the Navy Marine Species Density Database 
(NMSDD). A technical report will describe methodologies used to derive 
these densities, which are generally considered the best available 
information for Washington inland waters, except where specific local 
abundance information is available. Initial take estimates and impact 
assessment for the EHW-2 project relied on data available at the time 
the application was submitted, including survey efforts in the project 
area. For future projects at NBKB, it is likely that the NMSDD 
densities will be used in assessing project impacts. However, because 
the NMSDD report is not complete, and because use of the previous 
density or abundance information results in more conservative take 
estimates, the approach to take

[[Page 29725]]

estimation used for the first year of EHW-2 construction is largely 
retained here. Please see Appendix B of the Navy's application for more 
information on the NMSDD information.
    For all species, the most appropriate information available was 
used to estimate the number of potential incidences of take. For harbor 
seals, this involved published literature describing harbor seal 
research conducted in Washington and Oregon as well as more specific 
counts conducted in Hood Canal (Huber et al., 2001; Jeffries et al., 
2003). Killer whales are known from two periods of occurrence (2003 and 
2005) and are not known to preferentially use any specific portion of 
the Hood Canal. Therefore, density was calculated as the maximum number 
of individuals present at a given time during those occurrences 
(London, 2006), divided by the area of Hood Canal. The best information 
available for the remaining species in Hood Canal came from surveys 
conducted by the Navy at the NBKB waterfront or in the vicinity of the 
project area.
    Beginning in April 2008, Navy personnel have recorded sightings of 
marine mammals occurring at known haul-outs along the NBKB waterfront, 
including docked submarines or other structures associated with NBKB 
docks and piers and the nearshore pontoons of the floating security 
fence. Sightings of marine mammals within the waters adjoining these 
locations were also recorded. Sightings were attempted whenever 
possible during a typical work week (i.e., Monday through Friday), but 
inclement weather, holidays, or security constraints often precluded 
surveys. These sightings took place frequently, although without a 
formal survey protocol. During the surveys, staff visited each of the 
above-mentioned locations and recorded observations of marine mammals. 
Surveys were conducted using binoculars and the naked eye from 
shoreline locations or the piers/wharves themselves. Because these 
surveys consist of opportunistic sighting data from shore-based 
observers, largely of hauled-out animals, there is no associated survey 
area appropriate for use in calculating a density from the abundance 
data. Data were compiled for the period from April 2008 through 
December 2012 for analysis in this proposed IHA, and these data provide 
the basis for take estimation for Steller and California sea lions. 
Other information, including sightings data from other Navy survey 
efforts at NBKB, is available for these two species, but these data 
provide the most conservative (i.e., highest) local abundance estimates 
(and thus the highest estimates of potential take).
    In addition, vessel-based marine wildlife surveys were conducted 
according to established survey protocols during July through September 
2008 and November through May 2009-10 (Tannenbaum et al., 2009, 2011). 
Eighteen complete surveys of the nearshore area resulted in 
observations of four marine mammal species (harbor seal, California sea 
lion, harbor porpoise, and Dall's porpoise). These surveys operated 
along pre-determined transects parallel to the shoreline from the 
nearshore out to approximately 1,800 ft (549 m) from shoreline, at a 
spacing of 100 yd, and covered the entire NBKB waterfront 
(approximately 3.9 km\2\ per survey) at a speed of 5 kn or less. Two 
observers recorded sightings of marine mammals both in the water and 
hauled out, including date, time, species, number of individuals, age 
(juvenile, adult), behavior (swimming, diving, hauled out, avoidance 
dive), and haul-out location. Positions of marine mammals were obtained 
by recording distance and bearing to the animal with a rangefinder and 
compass, noting the concurrent location of the boat with GPS, and, 
subsequently, analyzing these data to produce coordinates of the 
locations of all animals detected. These surveys resulted in the only 
observation of a Dall's porpoise near NBKB.
    The Navy also conducted vessel-based line transect surveys in Hood 
Canal on non-construction days during the 2011 TPP in order to collect 
additional data for species present in Hood Canal. These surveys 
detected three marine mammal species (harbor seal, California sea lion, 
and harbor porpoise), and included surveys conducted in both the main 
body of Hood Canal, near the project area, and baseline surveys 
conducted for comparison in Dabob Bay, an area of Hood Canal that is 
not affected by sound from Navy actions at the NBKB waterfront. The 
surveys operated along pre-determined transects that followed a double 
saw-tooth pattern to achieve uniform coverage of the entire NBKB 
waterfront. The vessel traveled at a speed of approximately 5 kn when 
transiting along the transect lines. Two observers recorded sightings 
of marine mammals both in the water and hauled out, including the date, 
time, species, number of individuals, and behavior (swimming, diving, 
etc.). Positions of marine mammals were obtained by recording the 
distance and bearing to the animal(s), noting the concurrent location 
of the boat with GPS, and subsequently analyzing these data to produce 
coordinates of the locations of all animals detected. Sighting 
information for harbor porpoises was corrected for detectability (g(0) 
= 0.54; Barlow, 1988; Calambokidis et al., 1993; Carretta et al., 
2001). Distance sampling methodologies were used to estimate densities 
of animals for the data. This information provides the best information 
for harbor porpoises.
    The cetaceans, as well as the harbor seal, appear to range 
throughout Hood Canal; therefore, the analysis in this proposed IHA 
assumes that harbor seal, transient killer whale, harbor porpoise, and 
Dall's porpoise are uniformly distributed in the project area. However, 
it should be noted that there have been no observations of cetaceans 
within the floating security barriers at NBKB; these barriers thus 
appear to effectively prevent cetaceans from approaching the shutdown 
zones. Although the Navy will implement a precautionary shutdown zone 
for cetaceans, anecdotal evidence suggests that cetaceans are not at 
risk of Level A harassment at NBKB even from louder activities (e.g., 
impact pile driving). The remaining species that occur in the project 
area, Steller sea lion and California sea lion, do not appear to 
utilize most of Hood Canal. The sea lions appear to be attracted to the 
man-made haul-out opportunities along the NBKB waterfront while 
dispersing for foraging opportunities elsewhere in Hood Canal. 
California sea lions were not reported during aerial surveys of Hood 
Canal (Jeffries et al., 2000), and Steller sea lions have only been 
documented at the NBKB waterfront.

Description of Take Calculation

    The take calculations presented here rely on the best data 
currently available for marine mammal populations in the Hood Canal. 
The formula was developed for calculating take due to pile driving 
activity and applied to each group-specific sound impact threshold. The 
formula is founded on the following assumptions:
     Mitigation measures (e.g., bubble curtain) would be 
utilized, as discussed previously;
     All marine mammal individuals potentially available are 
assumed to be present within the relevant area, and thus incidentally 
taken;
     An individual can only be taken once during a 24-h period;
     There were will be 195 total days of activity;
     Exposure modeling assumes that one impact pile driver and 
three vibratory pile drivers are operating concurrently; and,
     Exposures to sound levels above the relevant thresholds 
equate to take, as defined by the MMPA.

[[Page 29726]]

    The calculation for marine mammal takes is estimated by:

Exposure estimate = (n * ZOI) * days of total activity

Where:

n = density estimate used for each species/season
ZOI = sound threshold ZOI impact area; the area encompassed by all 
locations where the SPLs equal or exceed the threshold being 
evaluated
n * ZOI produces an estimate of the abundance of animals that could 
be present in the area for exposure, and is rounded to the nearest 
whole number before multiplying by days of total activity.

    The ZOI impact area is the estimated range of impact to the sound 
criteria. The distances specified in Table 5 were used to calculate 
ZOIs around each pile. All impact pile driving take calculations were 
based on the estimated threshold ranges assuming attenuation of 10 dB 
from use of a bubble curtain. The ZOI impact area took into 
consideration the possible affected area of the Hood Canal from the 
pile driving site furthest from shore with attenuation due to land 
shadowing from bends in the canal. Because of the close proximity of 
some of the piles to the shore, the narrowness of the canal at the 
project area, and the maximum fetch, the ZOIs for each threshold are 
not necessarily spherical and may be truncated.
    While pile driving can occur any day throughout the in-water work 
window, and the analysis is conducted on a per day basis, only a 
fraction of that time (typically a matter of hours on any given day) is 
actually spent pile driving. Acoustic monitoring conducted as part of 
the TPP demonstrated that Level B harassment zones for vibratory pile 
driving are likely to be significantly smaller than the zones estimated 
through modeling based on measured source levels and practical 
spreading loss. Also of note is the fact that the effectiveness of 
mitigation measures in reducing takes is typically not quantified in 
the take estimation process. Here, we do explicitly account for an 
assumed level of efficacy for use of the bubble curtain, but not for 
the soft start associated with impact driving. In addition, equating 
exposure with response (i.e., a behavioral response meeting the 
definition of take under the MMPA) is simplistic and conservative 
assumption. For these reasons, these take estimates are likely to be 
conservative.
    Airborne Sound--No incidents of incidental take resulting solely 
from airborne sound are likely, as distances to the harassment 
thresholds would not reach areas where pinnipeds may haul out. Harbor 
seals can haul out at a variety of natural or manmade locations, but 
the closest known harbor seal haul-out is at the Dosewallips River 
mouth (London, 2006) and Navy waterfront surveys and boat surveys have 
found it rare for harbor seals to haul out along the NBKB waterfront 
(Agness and Tannenbaum, 2009; Tannenbaum et al., 2009, 2011; Navy, 
2010). Individual seals have occasionally been observed hauled out on 
pontoons of the floating security fence within the restricted areas of 
NBKB, but this area is not with the airborne disturbance ZOI. Nearby 
piers are elevated well above the surface of the water and are 
inaccessible to pinnipeds, and seals have not been observed hauled out 
on the adjacent shoreline. Sea lions typically haul out on submarines 
docked at Delta Pier, approximately one mile from the project site.
    We recognize that pinnipeds in the water could be exposed to 
airborne sound that may result in behavioral harassment when looking 
with heads above water. However, these animals would previously have 
been `taken' as a result 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. Multiple incidents of exposure to sound above NMFS' 
thresholds for behavioral harassment are not believed to result in 
increased behavioral disturbance, in either nature or intensity of 
disturbance reaction. Therefore, we do not believe that authorization 
of incidental take resulting from airborne sound for pinnipeds is 
warranted.
    California Sea Lion--California sea lions occur regularly in the 
vicinity of the project site from August through mid-June, as 
determined by Navy waterfront surveys conducted from April 2008 through 
December 2011 (Table 9). With regard to the range of this species in 
Hood Canal and the project area, it is assumed on the basis of 
waterfront observations (Agness and Tannenbaum, 2009; Tannenbaum et 
al., 2009, 2011) that the opportunity to haul out on submarines docked 
at Delta Pier is a primary attractant for California sea lions in Hood 
Canal, as they are not typically observed elsewhere in Hood Canal. 
Abundance is calculated as the monthly average of the maximum number 
observed in a given month, as opposed to the overall average (Table 9). 
That is, the maximum number of animals observed on any one day in a 
given month was averaged for 2008-11, providing a monthly average of 
the maximum daily number observed. The largest monthly average (58 
animals) was recorded in November, as was the largest single daily 
count (81 in 2011). The first California sea lion was observed at NBKB 
in August 2009, and their occurrence has been increasing since that 
time (Navy, 2012).
    California sea lion density for Hood Canal was calculated to be 
0.28 animals/km\2\ for purposes of the Navy Marine Species Density 
Database (Navy, 2013). However, this density was derived by averaging 
data collected year-round. This project will occur during the 
designated in-water work window, so it is more appropriate to use data 
collected at the NBKB waterfront during those months (July-February). 
The average of the monthly averages for maximum daily numbers observed 
(in a given month, during the in-water work window) is 31.2 animals 
(see Table 9). Exposures were calculated assuming 31 individuals could 
be present, and therefore exposed to sound exceeding the behavioral 
harassment threshold, on each day of pile driving. This methodology is 
conservative in that it assumes that all individuals potentially would 
be taken on any given day of activity.

              Table 9--California Sea Lion Sighting Information From NBKB, April 2008-December 2012
----------------------------------------------------------------------------------------------------------------
                                                                     Number of
                                                     Number of     surveys with    Frequency of
                      Month                           surveys         animals      presence \1\    Abundance \2\
                                                                      present
----------------------------------------------------------------------------------------------------------------
January.........................................              47              36            0.77            31.0
February........................................              50              43            0.86            38.0
March...........................................              47              45            0.96            53.3
April...........................................              67              55            0.82            45.4
May.............................................              72              58            0.81            29.4

[[Page 29727]]

 
June............................................              73              17            0.23             7.4
July............................................              61               1            0.02             0.6
August..........................................              65              12            0.18             2.6
September.......................................              54              31            0.57            20.4
October.........................................              65              61            0.94            51.8
November........................................              56              56            1               60.2
December........................................              54              44            0.81            49.6
                                                 ---------------------------------------------------------------
Total or average (in-water work season only)....             452             284            0.63            31.2
----------------------------------------------------------------------------------------------------------------
Totals (number of surveys) and averages (frequency and abundance) presented for in-water work season (July-
  February) only. Information from March-June presented for reference.
\1\ Frequency is the number of surveys with California sea lions present/number of surveys conducted.
\2\ Abundance is calculated as the monthly average of the maximum daily number observed in a given month.

Steller Sea Lion

    Steller sea lions were first documented at the NBKB waterfront in 
November 2008, while hauled out on submarines at Delta Pier and have 
been periodically observed from October to April since that time. Based 
on waterfront observations, Steller sea lions appear to use available 
haul-outs (typically in the vicinity of Delta Pier, approximately one 
mile south of the project area) and habitat similarly to California sea 
lions, although in lesser numbers. On occasions when Steller sea lions 
are observed, they typically occur in mixed groups with California sea 
lions also present, allowing observers to confirm their identifications 
based on discrepancies in size and other physical characteristics.
    Vessel-based survey effort in NBKB nearshore waters have not 
detected any Steller sea lions (Agness and Tannenbaum, 2009; Tannenbaum 
et al., 2009, 2011). Opportunistic sightings data provided by Navy 
personnel since April 2008 have continued to document sightings of 
Steller sea lions at Delta Pier from October through April (Table 10). 
Steller sea lions have only been observed hauled out on submarines 
docked at Delta Pier. Delta Pier and other docks at NBKB are not 
accessible to pinnipeds due to the height above water, although the 
smaller California sea lions and harbor seals are able to haul out on 
pontoons that support the floating security barrier. One to two animals 
are typically seen hauled out with California sea lions; the maximum 
Steller sea lion group size seen at any given time was six individuals 
(observed on four occasions).
    The calculation for exposure analysis is similar to that used for 
California sea lions. The average of the monthly averages for maximum 
daily numbers observed (in a given month, during the in-water work 
window) is 1.7 animals (see Table 10). Therefore, exposures were 
calculated assuming that two individuals could be present, and 
therefore exposed to sound exceeding the behavioral harassment 
threshold, on each day of pile driving. This methodology is 
conservative in that Steller sea lions are unlikely to be present on 
every day of pile driving and because it assumes that all individuals 
potentially would be taken on any given day of activity.

          Table 10--Steller Sea Lion Sighting Information From NBKB, April 2008-June 2010; October 2011
----------------------------------------------------------------------------------------------------------------
                                                                    Number of
                                                    Number of     surveys with    Frequency of
                     Month                           surveys         animals      presence \1\    Abundance \2\
                                                                     present
----------------------------------------------------------------------------------------------------------------
January........................................              47              12            0.26              1.5
February.......................................              50               6            0.12              1.3
March..........................................              47              12            0.26              1.8
April..........................................              67              21            0.31              2.8
May............................................              72               6            0.08              1.8
June...........................................              73               0            0                 0
July...........................................              61               0            0                 0
August.........................................              65               0            0                 0
September......................................              54               1            0.02              1.0
October........................................              65              26            0.40              2.6
November.......................................              56              30            0.54              4.6
December.......................................              54              18            0.33              2.6
                                                ----------------------------------------------------------------
Total or average (in-water work season only)...             452              93            0.21              1.7
----------------------------------------------------------------------------------------------------------------
Totals (number of surveys) and averages (frequency and abundance) presented for in-water work season (July-
  February) only. Information from March-June presented for reference.
\1\ Frequency is the number of surveys with Steller sea lions present/number of surveys conducted.
\2\ Abundance is calculated as the monthly average of the maximum daily number observed in a given month.

    Local abundance information, rather than density, was used in 
estimating take for Steller sea lions. Please see the discussion 
provided previously for California sea lions. Steller sea lions are 
known only from haul-outs over one

[[Page 29728]]

mile from the project area, and would not be subject to harassment from 
airborne sound. Table 10 depicts the number of estimated behavioral 
harassments.
    Harbor Seal--Jeffries et al. (2003) conducted aerial surveys of the 
harbor seal population in Hood Canal in 1999 for the Washington 
Department of Fish and Wildlife and reported 711 harbor seals hauled 
out. The authors adjusted this abundance with a correction factor of 
1.53 to account for seals in the water, which were not counted, and 
estimated that there were 1,088 harbor seals in Hood Canal. The 
correction factor (1.53) was based on the proportion of time seals 
spend on land versus in the water over the course of a day, and was 
derived by dividing one by the percentage of time harbor seals spent on 
land. These data came from tags (VHF transmitters) applied to harbor 
seals at six areas (Grays Harbor, Tillamook Bay, Umpqua River, Gertrude 
Island, Protection/Smith Islands, and Boundary Bay, BC) within two 
different harbor seal stocks (the coastal stock and the inland waters 
of WA stock) over four survey years. The Hood Canal population is part 
of the inland waters stock, and while not specifically sampled, 
Jeffries et al. (2003) found the VHF data to be broadly applicable to 
the entire stock. The tagging research in 1991 and 1992 conducted by 
Huber et al. (2001) and Jeffries et al. (2003) used the same methods 
for the 1999 and 2000 survey years. These surveys indicated that 
approximately 35 percent of harbor seals are in the water versus hauled 
out on a daily basis (Huber et al., 2001; Jeffries et al., 2003). 
Exposures were calculated using a density derived from the number of 
harbor seals that are present in the water at any one time (35 percent 
of 1,088, or approximately 381 individuals), divided by the area of the 
Hood Canal (358.44 km\2\) and the formula presented previously. The 
aforementioned area of Hood Canal represents a change from that cited 
previously for authorizations associated with Navy activities in Hood 
Canal, and represents a correction to our understanding of the 
methodology used in Jeffries et al. (2003).
    We recognize that over the course of the day, while the proportion 
of animals in the water may not vary significantly, different 
individuals may enter and exit the water. However, fine-scale data on 
harbor seal movements within the project area on time durations of less 
than a day are not available. Previous monitoring experience from Navy 
actions conducted in the same project area has indicated that this 
density provides an appropriate estimate of potential exposures. The 
density of harbor seals calculated in this manner (1.06 animals/km\2\) 
is corroborated by results of the Navy's vessel-based marine mammal 
surveys at NBKB in 2008 and 2009-10, in which an average of five 
individual harbor seals per survey was observed in the 3.9 km\2\ survey 
area (density = 1.3 animals/km\2\) (Tannenbaum et al., 2009, 2011). For 
this analysis, we retain the previous estimate of 1.3 animals/km\2\ 
(based on the erroneous understanding of the size of the sampling area 
used by Jeffries et al. (2003)), because the use of the older estimate 
is larger, therefore resulting in a conservative take estimate, and 
because incorporation of this correction here would result in 
unnecessary delay.
    Killer Whales--Transient killer whales are uncommon visitors to 
Hood Canal, and may be present anytime during the year. Transient pods 
(six to eleven individuals per event) were observed in Hood Canal for 
lengthy periods of time (59-172 days) in 2003 (January-March) and 2005 
(February-June), feeding on harbor seals (London, 2006). These whales 
used the entire expanse of Hood Canal for feeding. West Coast transient 
killer whales most often travel in small pods (Baird and Dill 1996). 
Houghton reported to the Navy, from unpublished data, that the most 
commonly observed group size in Puget Sound (defined as from Admiralty 
Inlet south and up through Skagit Bay) from 2004-2010 data is six 
whales.
    The density value derived for the Navy Marine Species Density 
Database is 0.0019 animals/km\2\ (Navy, 2013), which would result in a 
prediction that zero animals would be harassed by the project 
activities. However, while transient killer whales are rare in the Hood 
Canal, it is possible that a pod of animals could be present. In the 
event that this occurred, the animals would not assume a uniform 
distribution as is implied by the density estimate. For a separate 
activity occurring at NBKB (the barge mooring project), we 
conservatively assumed that a single pod of whales (defined as six 
whales) could be present in the vicinity of the project for the entire 
duration. However, the duration for that project is only twenty days, 
whereas the duration for EHW-2 is 195 days. While it is possible that 
killer whales could be present in Hood Canal for 195 days, we believe 
that it is unlikely even in the absence of a harassing stimulus on the 
basis of past observations. Further, in the absence of any overriding 
contextual element (e.g., NBKB is not important as a breeding area, and 
provides no unusual concentration of prey), it is reasonable to assume 
that whales would leave the area if exposed to potentially harassing 
levels of sound on each day that they were present. In the absence of 
such potentially harassing stimuli, killer whales were observed in Hood 
Canal in 2003 and 2005 for a minimum of 59 days. We assume here that a 
pod of whales would remain present for approximately half the time in 
the presence of pile driving (i.e., a pod of six whales present for 30 
days).

Dall's Porpoise

    Dall's porpoises may be present in the Hood Canal year-round and 
could occur as far south as the project site. Their use of inland 
Washington waters, however, is mostly limited to the Strait of Juan de 
Fuca. One individual has been observed by Navy staff in deeper waters 
of Hood Canal (Tannenbaum et al., 2009, 2011). The Navy Marine Species 
Density Database assumes a negligible value of 0.001 animals/1,000 
km\2\ for Dall's porpoises in the Hood Canal, which represents species 
that have historically been observed in an area but have no regular 
presence. Use of this density value results in a prediction that zero 
animals would be exposed to sound above the behavioral harassment 
threshold. However, given the lengthy project duration it is possible 
that a Dall's porpoise could be present. While it is unlikely that 
Dall's porpoise would be present frequently, there is no information to 
indicate an appropriate proportion of days, and the Navy is requesting 
authorization for one incidence of incidental take per day for Dall's 
porpoise.

Harbor Porpoise

    During vessel-based line transect surveys on non-construction days 
during the TPP, harbor porpoises were frequently sighted within several 
kilometers of the base, mostly to the north or south of the project 
area, but occasionally directly across from the Bangor waterfront on 
the far side of Toandos Peninsula. Harbor porpoise presence in the 
immediate vicinity of the base (i.e., within 1 km) remained low. These 
data were used to generate a density for Hood Canal. Based on guidance 
from other line transect surveys conducted for harbor porpoises using 
similar monitoring parameters (e.g., boat speed, number of observers) 
(Barlow, 1988; Calambokidis et al., 1993; Carretta et al., 2001), the 
Navy determined the effective strip width for the surveys to be one 
kilometer, or a perpendicular distance of 500 m from the transect to 
the left or right of the vessel. The effective strip width was set at 
the distance at which the detection probability for harbor porpoises 
was

[[Page 29729]]

equivalent to one, which assumes that all individuals on a transect are 
detected. Only sightings occurring within the effective strip width 
were used in the density calculation. By multiplying the trackline 
length of the surveys by the effective strip width, the total area 
surveyed during the surveys was 471.2 km\2\. Thirty-eight individual 
harbor porpoises were sighted within this area, resulting in a density 
of 0.0806 animals per km\2\. To account for availability bias, or the 
animals which are unavailable to be detected because they are 
submerged, the Navy utilized a g(0) value of 0.54, derived from other 
similar line transect surveys (Barlow, 1988; Calambokidis et al., 1993; 
Carretta et al., 2001). This resulted in a corrected density of 0.149 
harbor porpoises per km\2\. For comparison, 274.27 km\2\ of trackline 
survey effort in nearby Dabob Bay produced a corrected density estimate 
of 0.203 harbor porpoises per km\2\. However, the Navy has elected to 
retain an earlier density estimate, derived from only preliminary data, 
for the exposure analysis. This estimate is larger than the current 
best estimate and therefore overestimates the number of potential 
takes.
    Potential takes could occur if individuals of these species move 
through the area on foraging trips when pile driving is occurring. 
Individuals that are taken could exhibit behavioral changes such as 
increased swimming speeds, increased surfacing time, or decreased 
foraging. Most likely, individuals may move away from the sound source 
and be temporarily displaced from the areas of pile driving. Potential 
takes by disturbance would likely have a negligible short-term effect 
on individuals and not result in population-level impacts.

    Table 11--Number of Potential Incidental Takes of Marine Mammals Within Various Acoustic Threshold Zones
----------------------------------------------------------------------------------------------------------------
                                                            Underwater               Airborne
                                                 ------------------------------------------------
                                     Density/                        Vibratory                    Total proposed
             Species                 Abundance     Impact injury    disturbance       Impact        authorized
                                                   threshold \1\     threshold      disturbance        takes
                                                                   (120 dB) \2\    threshold \3\
----------------------------------------------------------------------------------------------------------------
California sea lion.............   \4\ 28.4                    0           6,045               0           6,045
Steller sea lion................    \4\ 1.1                    0             390               0             390
Harbor seal.....................    \5\ 1.06                   0          10,530               0          10,530
Killer whale....................    \6\ 0.0019                 0             180             N/A             180
Dall's porpoise.................    \6\ 0.000001               0             195             N/A             195
Harbor porpoise.................    \7\ 0.149                  0           1,950             N/A           1,950
----------------------------------------------------------------------------------------------------------------
\1\ Acoustic injury threshold for impact pile driving is 190 dB for pinnipeds and 180 dB for cetaceans.
\2\ The 160-dB acoustic harassment zone associated with impact pile driving would always be subsumed by the 120-
  dB harassment zone produced by vibratory driving. Therefore, takes are not calculated separately for the two
  zones.
\3\ Acoustic disturbance threshold is 100 dB for sea lions and 90 dB for harbor seals. We do not believe that
  pinnipeds would be available for airborne acoustic harassment because they are not known to regularly haul-out
  at locations inside the zone in which airborne acoustic harassment could occur.
\4\ Figures presented are abundance numbers, not density, and are calculated as the average of average daily
  maximum numbers per month. Abundance numbers are rounded to the nearest whole number for take estimation. The
  Steller sea lion abundance was doubled.
\5\ An uncorrected estimate of 1.3 animals/km\2\ was used for the exposure analysis.
\6\ These densities resulted in zero take estimates. We assumed that a single pod of six killer whales could be
  present for as many as 30 days of the duration and that one Dall's porpoise could be present on each day of
  the project.
\7\ The preliminary density estimate of 0.250 animals/km\2\ was used for the exposure analysis.

Negligible Impact and Small Numbers Analyses and Preliminary 
Determinations

    NMFS has defined ``negligible impact'' in 50 CFR 216.103 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.'' In making a negligible impact determination, 
we consider a variety of factors, including but not limited to: (1) The 
number of anticipated mortalities; (2) the number and nature of 
anticipated injuries; (3) the number, nature, intensity, and duration 
of Level B harassment; and (4) the context in which the take occurs.
    Pile driving activities associated with the wharf construction 
project, as outlined previously, have the potential to disturb or 
displace marine mammals. Specifically, the proposed activities may 
result in take, in the form of Level B harassment (behavioral 
disturbance) only, from airborne or underwater sounds generated from 
pile driving. No mortality, serious injury, or Level A harassment is 
anticipated given the methods of installation and measures designed to 
minimize the possibility of injury to marine mammals and Level B 
harassment would be reduced to the level of least practicable adverse 
impact. Specifically, vibratory hammers, which do not have significant 
potential to cause injury to marine mammals due to the relatively low 
source levels (less than 190 dB), would be the primary method of 
installation. Also, no impact pile driving will occur without the use 
of a sound attenuation system (e.g., bubble curtain), and pile driving 
will either not start or be halted if marine mammals approach the 
shutdown zone. The pile driving activities analyzed here are similar to 
other similar construction activities, including recent projects 
conducted by the Navy in the Hood Canal as well as work conducted in 
2005 for the Hood Canal Bridge (SR-104) by the Washington Department of 
Transportation, which have taken place with no reported injuries or 
mortality to marine mammals.
    The proposed numbers of animals authorized to be taken for Steller 
and California sea lions and for Dall's porpoises would be considered 
small relative to the relevant stocks or populations (each less than 
two percent) even if each estimated taking occurred to a new 
individual--an extremely unlikely scenario. For harbor porpoises, the 
number of incidences of take relative to the stock abundance 
(approximately eighteen percent) is higher, although still within the 
bounds of what we consider to be small numbers. Little is known about 
harbor porpoise use of Hood Canal, and prior to monitoring associated 
with recent pile driving projects at NBKB it was believed that harbor 
porpoise were

[[Page 29730]]

infrequent visitors to the area. It is unclear from the limited 
information available what relationship harbor porpoise occurrence in 
Hood Canal may hold to the regional stock or whether similar usage of 
Hood Canal may be expected to be recurring. It is unknown how many 
unique individuals are represented by sightings in Hood Canal, although 
it is unlikely that these animals represent a large proportion of the 
overall stock. Nevertheless, the estimated take of harbor porpoises is 
likely an overestimate, as sightings to date have occurred only at 
significant distance from the project area (both inside and outside of 
the predicted 120-dB zone).
    The proposed numbers of authorized take for harbor seals, transient 
killer whales, and harbor porpoises are somewhat higher relative to the 
total stocks. However, these numbers represent the instances of take, 
not the number of individuals taken. While it is unlikely that all 
animals in the Hood Canal population would be exposed to sound created 
by project activities, the approximately 1,088 harbor seals resident in 
Hood Canal are approximately seven percent of the regional stock, and 
represent small numbers of Washington inland waters harbor seals. For 
transient killer whales, we estimate take based on an assumption that a 
single pod of whales, comprising six individuals, is present in the 
vicinity of the project area for the entire duration of the project. 
These six individuals represent a small number of transient killer 
whales.
    For pinnipeds, no rookeries are present in the project area, there 
are no haul-outs other than those provided opportunistically by man-
made objects, and the project area is not known to provide foraging 
habitat of any special importance. Repeated exposures of individuals to 
levels of sound that may cause Level B harassment are unlikely to 
result in hearing impairment or to significantly disrupt foraging 
behavior. Thus, even repeated Level B harassment of some small subset 
of the overall stock is unlikely to result in any significant realized 
decrease in viability, and thus would not result in any adverse impact 
to the stock as a whole in terms of adverse effects on rates of 
recruitment or survival. The potential for multiple exposures of a 
small portion of the overall stock to levels associated with Level B 
harassment in this area is expected to have a negligible impact on the 
affected stocks.
    We have preliminarily determined that the impact of the previously 
described project may result, at worst, in a temporary modification in 
behavior (Level B harassment) of small numbers of marine mammals. No 
mortality or injuries are anticipated as a result of the specified 
activity, and none are proposed to be authorized. Additionally, animals 
in the area are not expected to incur hearing impairment (i.e., TTS or 
PTS) or non-auditory physiological effects. For pinnipeds, the absence 
of any major rookeries and only a few isolated and opportunistic haul-
out areas near or adjacent to the project site means that potential 
takes by disturbance would have an insignificant short-term effect on 
individuals and would not result in population-level impacts. 
Similarly, for cetacean species the absence of any known regular 
occurrence adjacent to the project site means that potential takes by 
disturbance would have an insignificant short-term effect on 
individuals and would not result in population-level impacts. Due to 
the nature, degree, and context of behavioral harassment anticipated, 
the activity is not expected to impact rates of recruitment or 
survival.
    For reasons stated previously in this document, the negligible 
impact determination is also supported by the likelihood that marine 
mammals are expected to move away from a sound source that is annoying 
prior to its becoming potentially injurious, and the likelihood that 
marine mammal detection ability by trained observers is high under the 
environmental conditions described for Hood Canal, enabling the 
implementation of shutdowns to avoid injury, serious injury, or 
mortality. As a result, no take by injury or death is anticipated, and 
the potential for temporary or permanent hearing impairment is very low 
and would be avoided through the incorporation of the proposed 
mitigation measures.
    While the numbers of marine mammals potentially incidentally 
harassed would depend on the distribution and abundance of marine 
mammals in the vicinity of the survey activity, the numbers are 
estimated to be small relative the affected species or population stock 
sizes, and have been mitigated to the lowest level practicable through 
incorporation of the proposed mitigation and monitoring measures 
mentioned previously in this document. This activity is expected to 
result in a negligible impact on the affected species or stocks. The 
Eastern DPS of the Steller sea lion is listed as threatened under the 
ESA; no other species for which take authorization is requested are 
either ESA-listed or considered depleted under the MMPA. No take would 
be authorized for humpback whales or southern resident killer whales, 
and the Navy would take appropriate action to avoid unauthorized 
incidental take should one of these species be observed in the project 
area.
    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 mitigation and monitoring 
measures, we preliminarily find that the proposed barge mooring project 
would result in the incidental take of small numbers of marine mammals, 
by Level B harassment only, and that the total taking from the activity 
would have a negligible impact on the affected species or stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    No tribal subsistence hunts are held in the vicinity of the project 
area; thus, temporary behavioral impacts to individual animals will not 
affect any subsistence activity. Further, no population or stock level 
impacts to marine mammals are anticipated or authorized. As a result, 
no impacts to the availability of the species or stock to the Pacific 
Northwest treaty tribes are expected as a result of the proposed 
activities. Therefore, no relevant subsistence uses of marine mammals 
are implicated by this action.

Endangered Species Act (ESA)

    There are two ESA-listed marine mammal species with known 
occurrence in the project area: The Eastern DPS of the Steller sea 
lion, listed as threatened, and the humpback whale, listed as 
endangered. Because of the potential presence of these species, the 
Navy engaged in a formal consultation with the NMFS Northwest Regional 
Office (NWR) under Section 7 of the ESA. We also initiated separate 
consultation with NWR because of our proposal to authorize the 
incidental take of Steller sea lions under the first IHA for EHW-2 
construction. NWR's Biological Opinion, issued on September 29, 2011, 
concluded that the effects of pile driving activities at NBKB were 
likely to adversely affect, but not likely to jeopardize the continued 
existence of the eastern DPS of Steller sea lion. The Steller sea lion 
does not have critical habitat in the action area. Subsequent to the 
completion of the biological opinion, NWR prepared an Incidental Take 
Statement (ITS) to be appended to the opinion.
    NWR compared the ITS, as well as the effects analysis and 
conclusions in the Biological Opinion, with the amount of and 
conditions on take proposed in the

[[Page 29731]]

IHA and determined that the effects of issuing an IHA to the Navy for 
the taking of Steller sea lions incidental to construction activities 
are consistent with those described in the opinion. The September 29, 
2011 Biological Opinion remains valid and this proposed MMPA 
authorization provides no new information about the effects of the 
action, nor does it change the extent of effects of the action, or any 
other basis to require reinitiation of the opinion. Therefore, the 
September 29, 2011 Biological Opinion meets the requirements of section 
7(a)(2) of the ESA and implementing regulations at 50 CFR 402 for both 
the Navy construction action, as well as our proposed action to issue 
an IHA under the MMPA, and no further consultation is required. NWR 
will issue a new ITS and append it to the 2011 Biological Opinion upon 
issuance of the IHA, if appropriate.

National Environmental Policy Act (NEPA)

    The Navy prepared an Environmental Impact Statement and issued a 
Record of Decision for this project. We acted as a cooperating agency 
in the preparation of that document, and reviewed the EIS and the 
public comments received and determined that preparation of additional 
NEPA analysis was not necessary. We subsequently adopted the Navy's EIS 
and issued our own Record of Decision for the issuance of the first IHA 
on July 6, 2012.
    We have reviewed the Navy's application for a renewed IHA for 
ongoing construction activities for 2013-14 and the 2012-13 monitoring 
report. Based on that review, we have determined that the proposed 
action follows closely the previous IHA and does not present any 
substantial changes, or significant new circumstances or information 
relevant to environmental concerns which would require preparation of a 
new or supplemental NEPA document. Therefore, we have preliminarily 
determined that a new or supplemental Environmental Assessment or EIS 
is unnecessary, and will, after review of public comments determine 
whether or not to reaffirm our 2012 ROD. The 2012 NEPA documents are 
available for review at https://www.nmfs.noaa.gov/pr/permits/incidental.htm.

Proposed Authorization

    As a result of these preliminary determinations, we propose to 
authorize the take of marine mammals incidental to the Navy's wharf 
construction project, provided the previously mentioned mitigation, 
monitoring, and reporting requirements are incorporated.

    Dated: May 16, 2013.
Helen M. Golde,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2013-12053 Filed 5-20-13; 8:45 am]
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