[Federal Register Volume 76, Number 245 (Wednesday, December 21, 2011)]
[Notices]
[Pages 79410-79439]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-32549]



[[Page 79409]]

Vol. 76

Wednesday,

No. 245

December 21, 2011

Part V





Department of Commerce





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 National Oceanic and Atmospheric Administration





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Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals; Notice

  Federal Register / Vol. 76 , No. 245 / Wednesday, December 21, 2011 / 
Notices  

[[Page 79410]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA830


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 January 
20, 2012.

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 20910-3225. The mailbox address for providing email 
comments is [email protected]. 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 
and will generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information 
(e.g., name, address) voluntarily submitted by the commenter may be 
publicly accessible. Do not submit Confidential Business Information or 
otherwise sensitive or protected information.
    An electronic copy of the application containing 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: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this 
notice may also be viewed, by appointment, during regular business 
hours, at the aforementioned 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]; 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

    NMFS received an application on May 25, 2011 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 August 11, 2011, and, responsive to 
discussions with NMFS as well as new information about species in the 
area, submitted a final version deemed adequate and complete by NMFS on 
November 3, 2011. The wharf construction project is proposed to occur 
over multiple years; however, this IHA would cover only the initial 
year of the project, from July 16, 2012, through July 15, 2013. 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 known from the waters surrounding NBKB: Steller sea lions 
(Eumetopias jubatus), California sea lions (Zalophus californianus), 
harbor seals (Phoca vitulina), killer whales (Orcinus orca), Dall's 
porpoises (Phocoenoides dalli), and harbor porpoises (Phocoena 
phocoena). 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). Additionally, while the Southern Resident killer whale (listed 
as endangered under the Endangered Species Act [ESA]) is resident to 
the inland waters of Washington and British Columbia, it has not been 
observed in the Hood Canal in over 15 years and was therefore excluded 
from further analysis.
    NBKB provides berthing and support services for OHIO Class 
ballistic missile submarines (SSBN), also known as TRIDENT submarines. 
The Navy proposes to begin construction of the Explosive Handling Wharf 
2 (EHW-2) facility at NBKB in order to support future program 
requirements for TRIDENT submarines berthed at NBKB. The Navy states 
that construction of EHW-2 is necessary because the existing EHW alone 
will not be able to support future TRIDENT 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

[[Page 79411]]

would be impact driven for their final 10-15 ft (3-4.6 m) 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 NMFS-promulgated 
thresholds for assessing pile driving and removal impacts (NMFS, 2005b, 
2009), outlined later in this document. The Navy used recommended 
spreading loss formulas (the practical spreading loss equation for 
underwater sounds and the spherical spreading loss equation for 
airborne sounds) and empirically-measured source levels from other 30-
66 in (0.8-1.7 m) diameter pile driving events to estimate potential 
marine mammal exposures. Predicted exposures are outlined later in this 
document. The calculations predict that no Level A harassments would 
occur associated with pile driving or construction activities, and that 
as many as 18,225 Level B harassments may occur during the wharf 
construction project from sound produced by pile driving activity.

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). NBKB provides berthing and support services for 
OHIO Class ballistic missile submarines (SSBN), also known as TRIDENT 
submarines. The Navy proposes to begin construction of the EHW-2 
facility at NBKB in order to support future program requirements for 
TRIDENT submarines berthed at NBKB. The Navy states that construction 
of EHW-2 is necessary because the existing EHW alone will not be able 
to support future TRIDENT program requirements. 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, 2012, and July 15, 2013. All in-water construction activities 
within the Hood Canal are only permitted during July 16-February 15 in 
order to protect spawning fish populations.
    As part of the Navy's sea-based strategic deterrence mission, the 
Navy Strategic Systems Programs directs research, development, 
manufacturing, testing, evaluation, and operational support for the 
TRIDENT Fleet Ballistic Missile program. Development of necessary 
facilities for handling of explosive materials is part of these duties. 
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 
Operations Area would include a support building and wharf cover. A 
warping wharf is a long, narrow wharf extension used to position 
submarines prior to moving into the Operations Area. The access 
trestles would allow vehicles to travel between the Operations Area and 
the shore.
    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 main wharf 
would include an operations support building providing office and 
storage space and mechanical/electrical system component housing. 
Additional facility support at the wharf would include heavy duty 
cranes suspended from the cover, power utility booms, six large 
lightning protection towers, and camels (operational platforms that 
float next to a moored vessel).
    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 during the first year; 
however, a maximum of 195 days of pile driving would occur. The 
analysis contained herein is based upon the maximum of 195 pile driving 
days, rather than any specific number of piles driven, and assumes that 
(1) all marine mammals available to be incidentally taken within the 
relevant area would be; and (2) individual marine mammals may only be 
incidentally taken once in a 24-h period--for purposes of authorizing 
specified numbers of take--regardless of actual number of exposures in 
that period. 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 first year of construction proposed 
for this IHA.

------------------------------------------------------------------------
                  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

[[Page 79412]]

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 a.m. and 10 p.m., year-round.
    The number of construction barges (derrick and material) on site at 
any one time would vary between two and eight depending on the type of 
construction taking place. The maximum number of eight barges would 
likely be present at the beginning of construction, with multiple rigs 
and their support barges required to complete the work at various areas 
of the wharf. As pile installation progresses, the area will become 
congested, limiting the space available to support the pile driving 
rigs and barges. Also, as sections of the wharf are completed the need 
for some of the rigs/barges will be reduced. As a result, fewer barges 
would likely be necessary as the project progresses. Tug boats would 
tow barges to and from the construction site and position the barges 
for construction activity. Tug boats would leave the site once these 
tasks were completed and so would not be on site for extended periods; 
there would be no more than two tug boats on site at any one time. Up 
to six smaller skiff-type boats would be on site performing various 
functions in support of construction and monitoring requirements.
    Operation of the EHW-2 would not result in an increase in boat 
traffic along the NBKB waterfront. Rather, a portion of the ongoing 
operations and boat traffic at the existing EHW and other facilities 
within the Waterfront Restricted Area (e.g., Delta Pier and Marginal 
Wharf) would be diverted to the EHW-2. The EHW-2 may be used as a 
backup explosives handling facility for TRIDENT submarines currently 
homeported at NBKB when there are no TRIDENT operations at the existing 
EHW. The EHW-2 may also provide temporary berthing when no ordnance 
handling operations are occurring at either wharf. No increase in boat 
traffic would be required to achieve planned operations. The increase 
in future operations at the waterfront would only require that boats 
remain at an EHW longer when in port for maintenance and upgrades. The 
overall level of traffic and activity along the NBKB waterfront would 
not increase as a result of operating the EHW-2. Operation of the EHW-2 
may require approximately twenty additional military and civilian 
personnel. The EHW-2 would be staffed 24 hours per day, 7 days per 
week. Maintenance of the EHW-2 would include routine inspections, 
repair, and replacement of facility components as required. It would 
not be necessary to replace piles during the design life of the EHW-2. 
Fouling organisms would not be removed from piles.

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 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

[[Page 79413]]

then taking the square root of the average (Urick, 1975). 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 [mu]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, 2002.
                                                         ft).
Vibratory driving of 72-in (1.8 m) steel      10-1,500  180 dB rms at 10 m (33 ft).  Illingworth and Rodkin,
 pipe pile.                                                                           2007.
Impact driving of 36-in steel pipe pile..     10-1,500  195 dB rms at 10 m.........  WSDOT, 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 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 (Caltrans, 
2009). Rise time is slower, reducing the probability and severity of 
injury (USFWS, 2009), and sound energy is distributed over a greater 
amount of time (Nedwell and Edwards, 2002; Carlson et al., 2001).

Ambient Sound

    The underwater acoustic environment consists of ambient sound, 
defined as environmental background sound levels

[[Page 79414]]

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).
    In the vicinity of the project area, the average broadband ambient 
underwater sound levels were measured at 114 dB re 1[mu]Pa between 100 
Hz and 20 kHz (Slater, 2009). Peak spectral sound 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 83-99 dB re 1[mu]Pa. Wind-driven 
wave sound dominated the background sound environment at approximately 
5 kHz and above, and ambient sound levels flattened above 10 kHz.
    Airborne sound levels at NBKB vary based on location but are 
estimated to average around 65 dBA (A-weighted decibels) in the 
residential and office park areas, with traffic sound ranging from 60-
80 dBA during daytime hours (Cavanaugh and Tocci, 1998). The highest 
levels of airborne sound are produced along the waterfront and at the 
ordnance handling areas, where estimated sound levels range from 70-90 
dBA and may peak at 99 dBA for short durations. These higher sound 
levels are produced by a combination of sound sources including heavy 
trucks, forklifts, cranes, marine vessels, mechanized tools and 
equipment, and other sound-generating industrial or military 
activities.

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. Bubble curtains 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 
(Caltrans, 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 (Caltrans, 2009).
    An isolation casing is a hollow pipe that surrounds the pile, 
isolating it from the in-water work area. The casing is dewatered 
before pile driving. This device provides levels of sound attenuation 
similar to that of bubble curtains (Caltrans, 2009). Sound levels can 
be reduced by 8 to 14 dB. Cushion blocks consist of materials (e.g., 
wood, nylon) placed atop piles during impact pile driving activities to 
reduce source levels. Typically sound reduction can range from 4 to a 
maximum of 26 dB.
    Cofferdams are often used during construction for isolating the in-
water work area, but may also be used as a sound attenuation device. 
Dewatered cofferdams may provide the highest levels of sound reduction 
of any attenuation device; however, they do not eliminate underwater 
sound because sound can be transmitted through the substrate (Caltrans, 
2009). Cofferdams that are not dewatered provide very limited reduction 
in sound levels.
    Both environmental conditions and the characteristics of the sound 
attenuation device may influence the effectiveness of the device. 
According to Caltrans (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., WSF, 2009; WSDOT, 2008; USFWS, 2009; 
Caltrans, 2009). 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 (Caltrans, 2009).

Sound Thresholds

    Since 1997, NMFS has used generic sound exposure thresholds to 
determine when an activity in the ocean that produces sound might 
result in impacts to a marine mammal such that a take by harassment 
might occur (NMFS, 2005b). 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 
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

[[Page 79415]]

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. A practical sound propagation 
modeling technique was used by the Navy to estimate the range from the 
pile driving activity to various SPL thresholds in water. This model 
follows a geometric propagation loss based on the distance from the 
driven pile, resulting in a 4.5 dB reduction in level for each doubling 
of distance from the source. In this model, the SPL at some distance 
away from the source (e.g., driven pile) is governed by a measured 
source level, minus the transmission loss of the energy as it 
dissipates with distance. The formula for underwater TL is:

TL = 15 * 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.

    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]). The propagation environment 
along the NBKB waterfront conforms to neither spherical nor cylindrical 
spreading; as the receiver moves away from the shoreline, the water 
increases in depth, resulting in an expected propagation environment 
that would lie between spherical and cylindrical spreading loss 
conditions. Since there is no available data regarding propagation loss 
along the NBKB waterfront, a practical spreading loss model was adopted 
as the most likely approximation of the sound propagation environment. 
Hydroacoustic monitoring results from the Navy's Test Pile Project (see 
76 FR 38361; July 30, 2011) will be used, when available, to confirm 
the validity of the practical spreading model for estimating acoustic 
propagation in the project area. That project concluded on October 31, 
2011.
    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. 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 affects on marine mammals that are 
likely to result from pile driving at NBKB, studies with similar 
properties to the proposed action were evaluated. Sound levels 
associated with vibratory pile removal are assumed to be the same as 
those during vibratory installation (Caltrans, 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      10 m (33 ft)...........  192 dB re 1 [micro]Pa
                                        pipe pile.                                        (rms) at 10 m (33 ft).
Friday Harbor Ferry Terminal, WA.....  30-in steel pipe pile..  10 m...................  196 dB re 1 [micro]Pa
                                                                                          (rms) at 10 m.
Unknown, CA..........................  36-in steel pipe pile..  10 m...................  193 dB re 1 [micro]Pa
                                                                                          (rms) at 10 m.
Mukilteo Test Piles, WA..............  36-in steel pipe pile..  7.3 m (24 ft)..........  195 dB re 1 [micro]Pa
                                                                                          (rms) at 10 m.
Anacortes Ferry, WA..................  36-in steel pipe pile..  12.8 m (42 ft).........  199 dB re 1 [micro]Pa
                                                                                          (rms) at 10 m.
Carderock Pier, NBKB, WA.............  42-in steel pipe pile..  14-22 m (48-70 ft).....  195 dB re 1 [micro]Pa
                                                                                          (rms) at 10 m.
Russian River, CA....................  48-in steel pipe pile..  2 m (6.6 ft)...........  195 dB re 1 [micro]Pa
                                                                                          (rms) at 10 m.
Unknown, CA..........................  60-in cast-in-steel-     10 m...................  195 dB re 1 [micro]Pa
                                        shell.                                            (rms) at 10 m.
Richmond-San Rafael Bridge, CA.......  66-in steel pipe pile..  4 m (13 ft)............  195 dB re 1 [micro]Pa
                                                                                          (rms) at 10 m.
----------------------------------------------------------------------------------------------------------------
Sources: WSDOT, 2005, 2008; Caltrans, 2007; Reyff, 2005; JASCO, 2005; Laughlin, 2005; Navy, 2009.

    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 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.

             Table 4--Underwater SPLs From Monitored Construction Activities Using Vibratory Hammers
----------------------------------------------------------------------------------------------------------------
         Project and location             Pile size and type          Water depth             Measured SPLs
----------------------------------------------------------------------------------------------------------------
Keystone Ferry Terminal, WA \1\......  30-in (0.8 m) steel      5 m (15 ft)............  164 dB re 1 [mu]Pa
                                        pipe pile.                                        (rms) at 10 m (33 ft).
Keystone Ferry Terminal, WA \1\......  30-in steel pipe pile..  8 m (28 ft)............  165 dB re 1 [mu]Pa
                                                                                          (rms) at 10 m.
Vashon Ferry Terminal, WA \2\........  30-in steel pipe pile..  6 m (20 ft)............  165 dB re 1 [mu]Pa
                                                                                          (rms) at 10 m.
Unknown, CA..........................  36-in steel pipe pile..  5 m....................  170 dB re 1 [mu]Pa
                                                                                          (rms) at 10 m.
Unknown, CA..........................  36-in steel pipe pile..  5 m....................  175 dB re 1 [mu]Pa
                                                                                          (rms) at 10 m.
Unknown, CA..........................  72-in steel pipe pile..  5 m....................  170 dB re 1 [mu]Pa
                                                                                          (rms) at 10 m.
Unknown, CA..........................  72-in steel pipe pile..  5 m....................  180 dB re 1 [mu]Pa
                                                                                          (rms) at 10 m.
----------------------------------------------------------------------------------------------------------------
Sources: Laughlin, 2010a; Laughlin, 2010b; Caltrans, 2007.


[[Page 79416]]

    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. The Navy 
will analyze data from the Test Pile Program to confirm the level of 
achieved sound attenuation from use of a bubble curtain or similar 
device using site-specific conditions.
    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). The 195 dB mean SPL of values presented 
in Table 3 was considered appropriate because it matched values from 
projects where larger-size pile was used and, in addition, matched the 
value obtained from the Carderock project, which was located at the 
NBKB waterfront and involved similar pile materials, water depth, and 
bottom type. The maximum value from Table 4 of 180 dB was deemed 
appropriate for vibratory driving because no data were available for 
48-in and 60-in piles. As a result, the most conservative value was 
selected. 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
------------------------------------------------------------------------
                                                          Area, km\2\
            Threshold                   Distance            (mi\2\)
------------------------------------------------------------------------
Impact driving, pinniped injury    4.9 m (16.1 ft)...  0.0001
 (190 dB).
Impact driving, cetacean injury    22 m (72.2 ft)....  0.002 (0.0008)
 (180 dB).
Impact driving, disturbance (160   724 m (2,375 ft)..  1.65 (0.64)
 dB)\2\.
Vibratory driving, pinniped        2.1 m (6.9 ft)....  < 0.0001
 injury (190 dB).
Vibratory driving, cetacean        10 m (32.8 ft)....  0.0003 (0.0001)
 injury (180 dB).
Vibratory driving, disturbance     13,800 m (45,276    41.4 (15.98)
 (120 dB).                          ft)\3\.
------------------------------------------------------------------------
\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.

    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 Propagation Formula--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. 
The appropriate airborne sound threshold for behavioral disturbance for 
all pinnipeds, except harbor seals, is 100 dB re 20 [micro]Pa rms 
(unweighted). For harbor seals, the threshold is 90 dB re 20 [micro]Pa 
rms (unweighted). A spherical spreading loss model, assuming average 
atmospheric conditions, was used to estimate the distance to the 100 dB 
and 90 dB re 20 [micro]Pa rms (unweighted) airborne thresholds. The 
formula for calculating spherical spreading loss is:

TL = 20log(R1/R2)
TL = Transmission loss
R1 = the distance of the modeled SPL from the driven 
pile, and
R2 = the distance from the driven pile of the initial 
measurement.

    Airborne Sound From Pile Installation--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.

[[Page 79417]]



                           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 m  97 dB re 20
                                  steel pipe pile.                         (40 ft).            [micro]Pa (rms)
                                                                                               at 160 m (525
                                                                                               ft).
Keystone Ferry Terminal, WA \3\  30-in (0.8 m)       Vibratory..........  Approximately 9 m   97 dB re 20
                                  steel pipe pile.                         (30 ft).            [micro]Pa (rms)
                                                                                               at 13 m (40 ft).
----------------------------------------------------------------------------------------------------------------
Sources: Blackwell et al., 2004; Laughlin, 2010b.

    Based on in-situ recordings from similar construction activities, 
the maximum airborne sound levels that would result from impact and 
vibratory pile driving are estimated to be 97 dB rms re 20 [mu]Pa at 
160 m and 97 dB rms re 20 [mu]Pa at 13 m, respectively (Blackwell et 
al., 2004; Laughlin, 2010b). The distances to the airborne thresholds 
were calculated with the airborne transmission loss formula presented 
previously. The Navy has analyzed the combined sound field produced 
under the multi-rig scenario and calculated the radial distances to the 
90 and 100 dB airborne thresholds as 361 m (1,184 ft) and 114 m (374 
ft), respectively, equating to areas of 0.41 km\2\ (0.16 mi\2\) and 
0.04 km\2\ (0.02 mi\2\), respectively. These distances would be 
significantly less for the vibratory driver alone, approximately 28 m 
(92 ft) and 9 m (30 ft), respectively.
    All airborne distances are less than those calculated for 
underwater sound thresholds. 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.

Description of Marine Mammals in the Area of the Specified Activity

    There are six marine mammal species, three 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, and 
the harbor seal. 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 15 years, and therefore was 
excluded from further analysis. The Steller sea lion is the only marine 
mammal that occurs within the Hood Canal which is listed under the ESA; 
the Eastern DPS is listed as threatened. All marine mammal species are 
protected under the MMPA. This section summarizes the population status 
and abundance of these species, followed by detailed life history 
information. Table 7 lists the marine mammal species that occur in the 
vicinity of NBKB and their estimated densities within the project area 
during the proposed timeframe. Daily maximum abundance data only is 
presented for sea lions because sightings data have no defined survey 
area.

                    Table 7--Marine Mammals Present in the Hood Canal in the Vicinity of NBKB
----------------------------------------------------------------------------------------------------------------
                                                                                                 Density during
                                                                                                  in-water work
             Species              Stock abundance \1\  Relative occurrence       Season of         season \3\
                                                          in Hood Canal         occurrence       (individuals/km
                                                                                                      \2\)
----------------------------------------------------------------------------------------------------------------
Steller sea lion
    Eastern U.S.DPS.............  58,334-72,223 \2\..  Occasional presence  Fall to late                 \3\ 1.2
                                                                             spring (Oct to
                                                                             mid-April).
California sea lion
    U.S. Stock..................  238,000............  Common.............  Fall to late                \3\ 26.2
                                                                             spring (Aug to
                                                                             early June).
Harbor seal
    WA inland waters stock......  14,612 (CV = 0.15).  Common.............  Year-round;                 \4\ 1.31
                                                                             resident species
                                                                             in Hood Canal.
Killer whale
    West Coast transient stock..  354................  Rare to occasional   Year-round........         \5\ 0.038
                                                        presence.
Dall's porpoise
    CA/OR/WA stock..............  42,000 (CV = 0.33).  Rare to occasional   Year-round........         \6\ 0.014
                                                        presence.
Harbor porpoise
    WA inland waters stock......  10,682 (CV = 0.38).  Possible regular to  Year-round........         \7\ 0.250
                                                        occasional
                                                        presence.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: http://www.nmfs.noaa.gov/pr/sars/species.htm.
\2\ Range calculated on basis of total pup counts 2006-2009 and extrapolation factors derived from vital rate
  parameters estimated for an increasing population.
\3\ Density for sea lions is not calculated due to the lack of a defined survey area for sightings data.
  Abundance calculated as the average of the maximum number of individuals present during shore-based surveys at
  NBKB waterfront during the in-water construction season.
\4\ Jeffries et al., 2003; Huber et al., 2001.
\5\ Density calculated as the maximum number of individuals present at a given time during occurrences of killer
  whales at Hood Canal in 2003 and 2005 (London 2006) divided by the area of Hood Canal.
\6\ Density calculated from number of individuals observed in 18 vessel-based surveys of NBKB waterfront area
  (Tannenbaum et al., 2009, 2011).

[[Page 79418]]

 
\7\ Density calculated from number of individuals observed during vessel-based surveys conducted during Test
  Pile Program and corrected for detectability (Navy, in prep.).

Steller Sea Lion

    Species Description--Steller sea lions are the largest members of 
the Otariid (eared seal) family. Steller sea lions show marked sexual 
dimorphism, in which adult males are noticeably larger and have 
distinct coloration patterns from females. Males average approximately 
1,500 lb (680 kg) and 10 ft (3 m) in length; females average about 700 
lb (318 kg) and 8 ft (2.4 m) in length. Adult females have a tawny to 
silver-colored pelt. Males are characterized by dark, dense fur around 
their necks, giving a mane-like appearance, and light tawny coloring 
over the rest of their body (NMFS, 2008a). Steller sea lions are 
distributed mainly around the coasts to the outer continental shelf 
along the North Pacific Ocean 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. The population 
is divided into the Western and the Eastern Distinct Population 
Segments (DPSs) at 144[deg]W (Cape Suckling, Alaska). The Western DPS 
includes Steller sea lions that reside in the central and western Gulf 
of Alaska, Aleutian Islands, as well as those that inhabit coastal 
waters and breed in Asia (e.g., Japan and Russia). The Eastern DPS 
extends from California to Alaska, including the Gulf of Alaska.
    Status--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 under the ESA in 1997 and the eastern 
stock remained classified as threatened. Animals found in the project 
area are from the eastern stock (NMFS, 1997a; Loughlin, 2002; Angliss 
and Outlaw, 2005). The eastern stock breeds in rookeries located in 
southeast Alaska, British Columbia, Oregon, and California; there are 
no rookeries located in Washington. A final revised species recovery 
plan addresses both stocks (NMFS, 2008a).
    Critical habitat was designated for Steller sea lions in 1993. 
Critical habitat is associated with breeding and haul-out sites in 
Alaska, California, and Oregon, and includes so-called `aquatic zones' 
that extend 3,000 ft (0.9 km) seaward in state and federally managed 
waters from the baseline or basepoint of each major rookery in Oregon 
and California (NMFS, 2008a). Three major rookery sites in Oregon 
(Rogue Reef, Pyramid Rock, and Long Brown Rock and Seal Rock on Orford 
Reef at Cape Blanco) and three rookery sites in California (Ano Nuevo 
I, Southeast Farallon I, and Sugarloaf Island and Cape Mendocino) are 
designated critical habitat (NMFS, 1993). There is no designated 
critical habitat within the project area.
    Limiting factors for recovery of Steller sea lions include reduced 
food availability, possibly resulting from competition with commercial 
fisheries; incidental take and intentional kills during commercial fish 
harvests; subsistence take; entanglement in marine debris; disease; 
pollution; and harassment. The change in food availability, associated 
with lowered nutritional status of females and consequent reduced 
juvenile recruitment, may be the primary cause of the decline (60 FR 
51968). Declines of this species in the early 1980s were associated 
with exceedingly low juvenile survivorship, whereas declines in the 
1990s were associated with disproportionately low fecundity (Holmes and 
York, 2003). Steller sea lions are also sensitive to disturbance at 
rookeries (during pupping and breeding) and haul-out sites.
    The abundance of the Eastern DPS of Steller sea lions is increasing 
throughout the northern portion of its range (Southeast Alaska and 
British Columbia), and stable or increasing slowly in the central 
portion (Oregon through central California). In the southern end of its 
range (Channel Islands in southern California), 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, 2007).
    The eastern stock was estimated by NMFS in the Recovery Plan for 
the Steller Sea Lion to number between 45,000 to 51,000 animals (NMFS, 
2008a). This stock has been increasing approximately three percent per 
year over the entire range since the late 1970s (NMFS, 2008a; Pitcher 
et al., 2007). The most recent population estimate for the eastern 
stock is a minimum of 52,847 individuals; this estimate is not 
corrected for animals at sea. Actual population is estimated to be 
within the range 58,334 to 72,223 (Allen and Angliss, 2010). The most 
recent minimum count for Steller sea lions in Oregon and Washington was 
5,813 in 2002 (Pitcher et al., 2007; Allen and Angliss, 2010).
    The eastern U.S. stock of Steller sea lion is currently listed as 
threatened under the ESA, and is therefore designated as depleted and 
classified as a strategic stock under the MMPA. However, the eastern 
stock of Steller sea lions has been considered a potential candidate 
for removal from listing under the ESA by the Steller sea lion recovery 
team and NMFS (NMFS, 2008), based on its annual rate of increase of 
approximately three percent since the mid-1970s. Although the stock 
size has increased, the status of this stock relative to its Optimum 
Sustainable Population (OSP) size is unknown. The overall annual rate 
of increase of 3.1 percent throughout most of the range (Oregon to 
southeastern Alaska) of the eastern stock has been consistent and long-
term, and may indicate that this stock is reaching OSP size (Pitcher et 
al., 2007).
    Behavior and Ecology--Steller sea lions forage near shore and in 
pelagic waters. They are capable of traveling long distances in a 
season and can dive to approximately 1,300 ft (400 m) in depth. They 
also use terrestrial habitat as haul-out sites for periods of rest, 
molting, and as rookeries for mating and pupping during the breeding 
season. At sea, they are often seen alone or in small groups, but may 
gather in large rafts at the surface near rookeries and haul-outs. 
Steller sea lions prefer the colder temperate to sub-arctic waters of 
the North Pacific Ocean. Haul-outs and rookeries usually consist of 
beaches (gravel, rocky or sand), ledges, and rocky reefs. In the Bering 
and Okhotsk Seas, sea lions may also haul-out on sea ice, but this is 
considered atypical behavior (NOAA, 2010a).
    Steller sea lions are gregarious animals that often travel or haul 
out in large groups of up to 45 individuals (Keple, 2002). At sea, 
groups usually consist of female and subadult males; adult males are 
usually solitary while at sea (Loughlin, 2002). In the Pacific 
Northwest, breeding rookeries are located in British Columbia, Oregon, 
and northern California. Steller sea lions form large rookeries during 
late spring when adult males arrive and establish territories (Pitcher 
and Calkins, 1981). Large males aggressively defend territories while 
non-breeding males remain at peripheral sites or haul-outs. Females 
arrive soon after and give birth. Most births occur from mid-May 
through mid-July, and breeding takes

[[Page 79419]]

place shortly thereafter. Most pups are weaned within a year. Non-
breeding individuals may not return to rookeries during the breeding 
season but remain at other coastal haul-outs (Scordino, 2006).
    Steller sea lions are opportunistic predators, feeding primarily on 
fish and cephalopods, and their diet varies geographically and 
seasonally (Bigg, 1985; Merrick et al., 1997; Bredesen et al., 2006; 
Guenette et al., 2006). Foraging habitat is primarily shallow, 
nearshore and continental shelf waters; freshwater rivers; and also 
deep waters (Reeves et al., 2008; Scordino, 2010). Steller sea lions 
occupy major winter haul-out sites on the coast of Vancouver Island in 
the Strait of Juan de Fuca and the Georgia Basin (Bigg, 1985; Olesiuk, 
2008); the closest breeding rookery to the project area is at Carmanah 
Point near the western entrance to the Strait of Juan de Fuca. There 
are no known breeding rookeries in Washington (NMFS, 1992; Angliss and 
Outlaw, 2005) but Eastern stock Steller sea lions are present year-
round along the outer coast of Washington at four major haul-out sites 
(NMFS, 2008a). Both sexes are present in Washington waters; these 
animals are likely immature or non-breeding adults from rookeries in 
other areas (NMFS, 2008a). In Washington, Steller sea lions primarily 
occur at haul-out sites along the outer coast from the Columbia River 
to Cape Flattery. In inland waters, Steller sea lions use haul-out 
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). The highest 
breeding season Steller sea lion count at Washington haul-out sites was 
847 individuals during the period from 1978 to 2001 (Pitcher et al., 
2007). Non-breeding season surveys of Washington haul-out sites 
reported as many as 1,458 individuals between 1980 and 2001 (NMFS, 
2008a).
    Steller sea lions are occasionally present at the Toliva Shoals 
haul-out site in south Puget Sound (Jeffries et al., 2000) and a rock 
three miles south of Marrowstone Island (NMFS, 2010). Fifteen Steller 
sea lions have been observed using this haul-out site. At NBKB, Steller 
sea lions have been observed hauled out on submarines at Delta Pier on 
several occasions from 2008 through 2011 during fall through spring 
months (October to April) (Navy 2010). Other potential haul-out sites 
may include isolated islands, rocky shorelines, jetties, buoys, rafts, 
and floats (Jeffries et al., 2000). Steller sea lions likely utilize 
foraging habitats in Hood Canal similar to those of the California sea 
lion and harbor seal, which include marine nearshore and deeper water 
habitats.
    Acoustics--Like all pinnipeds, the Steller sea lion is amphibious; 
while all foraging activity takes place in the water, breeding behavior 
is carried out on land in coastal rookeries (Mulsow and Reichmuth 
2008). On land, territorial male Steller sea lions regularly use loud, 
relatively low-frequency calls/roars to establish breeding territories 
(Schusterman et al., 1970; Loughlin et al., 1987). The calls of females 
range from 0.03 to 3 kHz, with peak frequencies from 0.15 to 1 kHz; 
typical duration is 1.0 to 1.5 sec (Campbell et al., 2002). Pups also 
produce bleating sounds. Individually distinct vocalizations exchanged 
between mothers and pups are thought to be the main modality by which 
reunion occurs when mothers return to crowded rookeries following 
foraging at sea (Mulsow and Reichmuth, 2008).
    Mulsow and Reichmuth (2008) measured the unmasked airborne hearing 
sensitivity of one male Steller sea lion. The range of best hearing 
sensitivity was between 5 and 14 kHz. Maximum sensitivity was found at 
10 kHz, where the subject had a mean threshold of 7 dB. The underwater 
hearing threshold of a male Steller sea lion was significantly 
different from that of a female. The peak sensitivity range for the 
male was from 1 to 16 kHz, with maximum sensitivity (77 dB re: 1[mu]Pa-
m) at 1 kHz. The range of best hearing for the female was from 16 to 
above 25 kHz, with maximum sensitivity (73 dB re: 1[mu]Pa-m) at 25 kHz. 
However, because of the small number of animals tested, the findings 
could not be attributed to either individual differences in sensitivity 
or sexual dimorphism (Kastelein et al., 2005).

California Sea Lion

    Species Description--California sea lions are members of the 
Otariid family (eared seals). The species, Zalophus californianus, 
includes three subspecies: Z. c. wollebaeki (in the Galapagos Islands), 
Z. c. japonicus (in Japan, but now thought to be extinct), and Z. c. 
californianus (found from southern Mexico to southwestern Canada; 
referred to here as the California sea lion) (Carretta et al., 2007). 
The California sea lion is sexually dimorphic. Males may reach 1,000 lb 
(454 kg) and 8 ft (2.4 m) in length; females grow to 300 lb (136 kg) 
and 6 ft (1.8 m) in length. Their color ranges from chocolate brown in 
males to a lighter, golden brown in females. At around five years of 
age, males develop a bony bump on top of the skull called a sagittal 
crest. The crest is visible in the dog-like profile of male sea lion 
heads, and hair around the crest gets lighter with age.
    Status--The U.S. stock of California sea lions is estimated at 
238,000 and the minimum population size of this stock is 141,842 
individuals (Carretta et al., 2007). These numbers are from counts 
during the 2001 breeding season of animals that were ashore at the four 
major rookeries in southern California and at haul-out sites north to 
the Oregon/California border. Sea lions that were at-sea or hauled-out 
at other locations were not counted (Carretta et al., 2007). The stock 
has likely reached its carrying capacity and, even though current total 
human-caused mortality is unknown (due to a lack of observer coverage 
in the California set gillnet fishery that historically has been the 
largest source of human-caused mortalities), California sea lions are 
not considered a strategic stock under the MMPA because total human-
caused mortality is still likely to be less than the potential 
biological removal (PBR). An estimated 3,000 to 5,000 California sea 
lions migrate to waters of Washington and British Columbia during the 
non-breeding season from September to May (Jeffries et al., 2000). 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).
    Distribution--The geographic distribution of California sea lions 
includes a breeding range from Baja California, Mexico to southern 
California. During the summer, California sea lions breed on islands 
from the Gulf of California to the Channel Islands and seldom travel 
more than about 31 mi (50 km) from the islands (Bonnell et al., 1983). 
The primary rookeries are located on the California Channel Islands of 
San Miguel, San Nicolas, Santa Barbara, and San Clemente (Le Boeuf and 
Bonnell, 1980; Bonnell and Dailey, 1993). Their distribution shifts to 
the northwest in fall and to the southeast during winter and spring, 
probably in response to changes in prey availability (Bonnell and Ford, 
1987).
    The non-breeding distribution extends from Baja California north to 
Alaska for males, and encompasses the waters of California and Baja 
California for females (Reeves et al., 2008; Maniscalco et al., 2004). 
In the non-breeding season, an estimated 3,000-5,000 adult and sub-
adult males migrate northward along the coast to central and northern 
California, Oregon,

[[Page 79420]]

Washington, and Vancouver Island from September to May (Jeffries et 
al., 2000) and return south the following spring (Mate, 1975; Bonnell 
et al., 1983). Along their migration, they are occasionally sighted 
hundreds of miles offshore (Jefferson et al., 1993). Females and 
juveniles tend to stay closer to the rookeries (Bonnell et al., 1983).
    California sea lions are present in Hood Canal during much of the 
year with the exception of mid-June through August, and occur regularly 
in the vicinity of the project site, as observed during Navy waterfront 
surveys conducted at NBKB from April 2008 through June 2010 (Navy, 
2010). They are known to utilize man-made structures such as piers, 
jetties, offshore buoys, log booms, and oil platforms (Riedman, 1990), 
and are often seen rafted off of river mouths (Jeffries et al., 2000). 
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 58 California 
sea lions have been observed hauled out together at NBKB (Agness and 
Tannenbaum, 2009a; Tannenbaum et al., 2009a; Walters, 2009). California 
sea lions have also been observed swimming in the Hood Canal in the 
vicinity of the project area on several occasions and likely forage in 
both nearshore marine and inland marine deeper waters (DoN, 2001a).
    Behavior and Ecology--California sea lions feed on a wide variety 
of prey, including many species of fish and squid (Everitt et al., 
1981; Roffe and Mate, 1984; Antonelis et al., 1990; Lowry et al., 
1991). In the Puget Sound region, they feed primarily on fish such as 
Pacific hake (Merluccius productus), walleye pollock (Theragra 
chalcogramma), Pacific herring (Clupea pallasii), and spiny dogfish 
(Squalus acanthias) (Calambokidis and Baird, 1994). In some locations 
where salmon runs exist, California sea lions also feed on returning 
adult and out-migrating juvenile salmonids (London, 2006). Sexual 
maturity occurs at around four to five years of age for California sea 
lions (Heath, 2002). California sea lions are gregarious during the 
breeding season and social on land during other times.
    Acoustics--On land, California sea lions make incessant, raucous 
barking sounds; these have most of their energy at less than 2 kHz 
(Schusterman et al., 1967). Males vary both the number and rhythm of 
their barks depending on the social context; the barks appear to 
control the movements and other behavior patterns of nearby 
conspecifics (Schusterman, 1977). Females produce barks, squeals, 
belches, and growls in the frequency range of 0.25-5 kHz, while pups 
make bleating sounds at 0.25-6 kHz. California sea lions produce two 
types of underwater sounds: clicks (or short-duration sound pulses) and 
barks (Schusterman et al., 1966, 1967; Schusterman and Baillet, 1969). 
All underwater sounds have most of their energy below 4 kHz 
(Schusterman et al., 1967).
    The range of maximal hearing sensitivity underwater is between 1-28 
kHz (Schusterman et al., 1972). Functional underwater high frequency 
hearing limits are between 35-40 kHz, with peak sensitivities from 15-
30 kHz (Schusterman et al., 1972). The California sea lion shows 
relatively poor hearing at frequencies below 1 kHz (Kastak and 
Schusterman, 1998). Peak hearing sensitivities in air are shifted to 
lower frequencies; the effective upper hearing limit is approximately 
36 kHz (Schusterman, 1974). The best range of sound detection is from 
2-16 kHz (Schusterman, 1974). Kastak and Schusterman (2002) determined 
that hearing sensitivity generally worsens with depth--hearing 
thresholds were lower in shallow water, except at the highest frequency 
tested (35 kHz), where this trend was reversed. Octave band sound 
levels of 65-70 dB above the animal's threshold produced an average 
temporary threshold shift (TTS; discussed later in ``Potential Effects 
of the Specified Activity on Marine Mammals'') of 4.9 dB in the 
California sea lion (Kastak et al., 1999).

Harbor Seal

    Species Description--Harbor seals, which are members of the Phocid 
family (true seals), inhabit coastal and estuarine waters and shoreline 
areas from Baja California, Mexico to western Alaska. For management 
purposes, differences in mean pupping date (i.e., birthing) (Temte, 
1986), movement patterns (Jeffries, 1985; Brown, 1988), pollutant loads 
(Calambokidis et al., 1985) and fishery interactions have led to the 
recognition of three separate harbor seal stocks along the west coast 
of the continental U.S. (Boveng, 1988). The three distinct stocks are: 
(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., 2007). The 
inland waters of Washington stock is the only stock that is expected to 
occur within the project area.
    The average weight for adult seals is about 180 lb (82 kg) and 
males are slightly larger than females. Male harbor seals weigh up to 
245 lb (111 kg) and measure approximately 5 ft (1.5 m) in length. The 
basic color of harbor seals' coat is gray and mottled but highly 
variable, from dark with light color rings or spots to light with dark 
markings (NMFS, 2008c).
    Status--Estimated population numbers for the inland waters of 
Washington, including the Hood Canal, Puget Sound, and the Strait of 
Juan de Fuca out to Cape Flattery, are 14,612 individuals (Carretta et 
al., 2007). The minimum population is 12,844 individuals. The harbor 
seal is the only species of marine mammal that is consistently abundant 
and considered resident in the Hood Canal (Jeffries et al., 2003). The 
population of harbor seals in Hood Canal is a closed population, 
meaning that they do not have much movement outside of Hood Canal 
(London, 2006). The abundance of harbor seals in Hood canal has 
stabilized, and the population may have reached its carrying capacity 
in the mid-1990s with an approximate abundance of 1,000 harbor seals 
(Jeffries et al., 2003).
    Harbor seals are not considered to be depleted under the MMPA or 
listed under the ESA. Human-caused mortality relative to PBR is 
unknown, but it is considered to be small relative to the stock size. 
Therefore, the Washington Inland Waters stock of harbor seals is not 
classified as a strategic stock.
    Distribution--Harbor seals are coastal species, rarely found more 
than 12 mi (20 km) from shore, and frequently occupy bays, estuaries, 
and inlets (Baird 2001). Individual seals have been observed several 
miles upstream in coastal rivers. Ideal harbor seal habitat includes 
haul-out sites, shelter during the breeding periods, and sufficient 
food (Bjorge, 2002). Haul-out areas can include intertidal and subtidal 
rock outcrops, sandbars, sandy beaches, peat banks in salt marshes, and 
man-made structures such as log booms, docks, and recreational floats 
(Wilson, 1978; Prescott, 1982; Schneider and Payne, 1983; Gilber and 
Guldager, 1998; Jeffries et al., 2000). Human disturbance can affect 
haul-out choice (Harris et al., 2003).
    Harbor seals occur throughout Hood Canal and are seen relatively 
commonly in the area. They are year-round, non-migratory residents, and 
pup (i.e., give birth) in Hood Canal. Surveys in the Hood Canal from 
the mid-1970s to 2000 show a fairly stable population between 600-1,200 
seals (Jeffries et al., 2003). Harbor seals have been observed swimming 
in the waters along NBKB in every month of surveys conducted from 2007-
2010 (Agness and Tannenbaum,

[[Page 79421]]

2009b; Tannenbaum et al., 2009b). On the NBKB waterfront, harbor seals 
have not been observed hauling out in the intertidal zone, but have 
been observed hauled-out on man-made structures such as the floating 
security fence, buoys, barges, marine vessels, and logs (Agness and 
Tannebaum, 2009a; Tannenbaum et al., 2009a). The main haul-out 
locations for harbor seals in Hood Canal are located on river delta and 
tidal exposed areas at Quilcene, Dosewallips, Duckabush, Hamma Hamma, 
and Skokomish River mouths (see Figure 4-1 of the Navy's application), 
with the closest haul-out area to the project area being ten miles (16 
km) southwest of NBKB at Dosewallips River mouth, outside the potential 
area of effect for this project (London, 2006).
    Behavior and Ecology--Harbor seals are typically seen in small 
groups resting on tidal reefs, boulders, mudflats, man-made structures, 
and sandbars. Harbor seals are opportunistic feeders that adjust their 
patterns to take advantage of locally and seasonally abundant prey 
(Payne and Selzer 1989; Baird 2001; Bj[oslash]rge 2002). The harbor 
seal diet consists of fish and invertebrates (Bigg, 1981; Roffe and 
Mate, 1984; Orr et al., 2004). Although harbor seals in the Pacific 
Northwest are common in inshore and estuarine waters, they primarily 
feed at sea (Orr et al., 2004) during high tide. Researchers have found 
that they complete both shallow and deep dives during hunting depending 
on the availability of prey (Tollit et al., 1997). Their diet in Puget 
Sound consists of many of the prey resources that are present in the 
nearshore and deeper waters of NBKB, including hake, herring and adult 
and out-migrating juvenile salmonids. Harbor seals in Hood Canal are 
known to feed on returning adult salmon, including ESA-threatened 
summer-run chum (Oncorhynchus keta). Over a 5-year study of harbor seal 
predation in the Hood Canal, the average percent escapement of summer-
run chum consumed was eight percent (London, 2006).
    Harbor seals mate at sea and females give birth during the spring 
and summer, although the pupping season varies by latitude. In coastal 
and inland regions of Washington, pups are born from April through 
January. Pups are generally born earlier in the coastal areas and later 
in the Puget Sound/Hood Canal region (Calambokidis and Jeffries, 1991; 
Jeffries et al., 2000). Suckling harbor seal pups spend as much as 
forty percent of their time in the water (Bowen et al., 1999).
    Acoustics--In air, harbor seal males produce a variety of low-
frequency (less than 4 kHz) vocalizations, including snorts, grunts, 
and growls. Male harbor seals produce communication sounds in the 
frequency range of 100-1,000 Hz (Richardson et al., 1995). Pups make 
individually unique calls for mother recognition that contain multiple 
harmonics with main energy below 0.35 kHz (Bigg, 1981; Thomson and 
Richardson, 1995). Harbor seals hear nearly as well in air as 
underwater and had lower thresholds than California sea lions (Kastak 
and Schusterman, 1998). Kastak and Schusterman (1998) reported airborne 
low frequency (100 Hz) sound detection thresholds at 65.4 dB re 20 
[mu]Pa for harbor seals. In air, they hear frequencies from 0.25-30 kHz 
and are most sensitive from 6-16 kHz (Richardson, 1995; Terhune and 
Turnbull, 1995; Wolski et al., 2003).
    Adult males also produce underwater sounds during the breeding 
season that typically range from 0.25-4 kHz (duration range: 0.1 s to 
multiple seconds; Hanggi and Schusterman 1994). Hanggi and Schusteman 
(1994) found that there is individual variation in the dominant 
frequency range of sounds between different males, and Van Parijs et 
al. (2003) reported oceanic, regional, population, and site-specific 
variation that could be vocal dialects. In water, they hear frequencies 
from 1-75 kHz (Southall et al., 2007) and can detect sound levels as 
weak as 60-85 dB re 1 [mu]Pa within that band. They are most sensitive 
at frequencies below 50 kHz; above 60 kHz sensitivity rapidly 
decreases.

Killer Whale

    Species Description--Killer whales are members of the Delphinid 
family and are the most widely distributed cetacean species in the 
world. Killer whales have a distinctive color pattern, with black 
dorsal and white ventral portions. They also have a conspicuous white 
patch above and behind the eye and a highly variable gray or white 
saddle area behind the dorsal fin. The species shows considerable 
sexual dimorphism. Adult males develop larger pectoral flippers, dorsal 
fins, tail flukes, and girths than females. Male adult killer whales 
can reach up to 32 ft (9.8 m) in length and weigh nearly 22,000 lb 
(10,000 kg); females reach 28 ft (8.5 m) in length and weigh up to 
16,500 lb (7,500 kg).
    Based on appearance, feeding habits, vocalizations, social 
structure, and distribution and movement patterns there are three types 
of populations of killer whales (Wiles, 2004; NMFS, 2005). The three 
distinct forms or types of killer whales recognized in the North 
Pacific Ocean are: (1) Resident, (2) Transient, and (3) Offshore. The 
resident and transient populations have been divided further into 
different subpopulations based mainly on genetic analyses and 
distribution; not enough is known about the offshore whales to divide 
them into subpopulations (Wiles, 2004). Only transient killer whales 
are known from the project area.
    Transient killer whales occur throughout the eastern North Pacific, 
and have primarily been studied in coastal waters. Their geographical 
range overlaps that of the resident and offshore killer whales. The 
dorsal fin of transient whales tends to be more erect (straighter at 
the tip) than those of resident and offshore whales (Ford and Ellis, 
1999; Ford et al., 2000). Saddle patch pigmentation of transient killer 
whales is restricted to two patterns, and never has the large areas of 
black pigmentation intruding into the white of the saddle patch that is 
seen in resident and offshore types. Transient type whales are often 
found in long-term stable social units that tend to be smaller than 
resident social groups (e.g., fewer than ten whales); these social 
units do not seem as permanent as matrilines are in resident type 
whales. Transient killer whales feed nearly exclusively on marine 
mammals (Ford and Ellis, 1999), whereas resident whales primarily eat 
fish. Offshore whales are presumed to feed primarily on fish, and have 
been documented feeding on sharks.
    Within the transient type, association data (Ford et al., 1994; 
Ford and Ellis, 1999; Matkin et al., 1999), acoustic data (Saulitis, 
1993; Ford and Ellis, 1999) and genetic data (Hoelzel et al., 1998, 
2002; Barrett-Lennard, 2000) confirms that three communities of 
transient whales exist and represent three discrete populations: (1) 
Gulf of Alaska, Aleutian Islands, and Bering Sea transients, (2) AT1 
transients (Prince William Sound, AK; listed as depleted under the 
MMPA), and (3) West Coast transients. Among the genetically distinct 
assemblages of transient killer whales in the northeastern Pacific, 
only the West Coast transient stock, which occurs from southern 
California to southeastern Alaska, may occur in the project area.
    Status--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 a minimum number of 354 individuals 
for the West Coast transient stock (Allen and Angliss,

[[Page 79422]]

2010). 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. Population trends and status of this stock relative to 
its Optimum Sustainable Population (OSP) level are currently unknown.
    Distribution--The geographical range of transient killer whales 
includes the northeast Pacific, with preference for coastal waters of 
southern Alaska and British Columbia (Krahn et al., 2002). Transient 
killer whales in the eastern North Pacific spend most of their time 
along the outer coast, but visit Hood Canal and the Puget Sound in 
search of harbor seals, sea lions, and other prey. Transient occurrence 
in inland waters appears to peak during August and September (Morton, 
1990; Baird and Dill, 1995; Ford and Ellis, 1999) 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) visited Hood Canal to feed 
on harbor seals and remained in the area for significant periods of 
time (59 and 172 days, respectively) between the months of January and 
July.
    Behavior and Ecology--Transient killer whales show greater 
variability in habitat use, with some groups spending most of their 
time foraging in shallow waters close to shore while others hunt almost 
entirely in open water (Felleman et al., 1991; Baird and Dill, 1995; 
Matkin and Saulitis, 1997). Transient killer whales feed on marine 
mammals and some seabirds, but apparently no fish (Morton, 1990; Baird 
and Dill, 1996; Ford et al., 1998; Ford and Ellis, 1999; Ford et al., 
2005). While present in Hood Canal in 2003 and 2005, transient killer 
whales preyed on harbor seals in the subtidal zone of the nearshore 
marine and inland marine deeper water habitats (London, 2006). Other 
observations of foraging transient killer whales indicate they prefer 
to forage on pinnipeds in shallow, protected waters (Heimlich-Boran, 
1988; Saulitis et al., 2000). Transient killer whales travel in small, 
matrilineal groups, but they typically contain fewer than ten animals 
and their social organization generally is more flexible than that of 
resident killer whales (Morton, 1990, Ford and Ellis, 1999). These 
differences in social organization probably relate to differences in 
foraging (Baird and Whitehead, 2000). There is no information on the 
reproductive behavior of killer whales in this area.
    Acoustics--Killer whales produce a wide variety of clicks and 
whistles, but most of their sounds are pulsed, with frequencies ranging 
from 0.5-25 kHz (dominant frequency range: 1-6 kHz) (Thomson and 
Richardson, 1995; Richardson et al., 1995). Source levels of 
echolocation signals range between 195-224 dB re 1 [mu]Pa-m peak-to-
peak (p-p), dominant frequencies range from 20-60 kHz, with durations 
of about 0.1 s (Au et al., 2004). Source levels associated with social 
sounds have been calculated to range between 131-168 dB re 1 [mu]Pa-m 
and vary with vocalization type (Veirs, 2004).
    Both behavioral and auditory brainstem response techniques indicate 
killer whales can hear in a frequency range of 1-100 kHz and are most 
sensitive at 20 kHz. This is one of the lowest maximum-sensitivity 
frequencies known among toothed whales (Szymanski et al., 1999).

Dall's Porpoise

    Species Description--Dall's porpoises are members of the Phocoenid 
(porpoise) family and are common in the North Pacific Ocean. They can 
reach a maximum length of just under 8 ft (2.4 m) and weigh up to 480 
lb (218 kg). Males are slightly larger and thicker than females, which 
reach lengths of just under 7 ft (2.1 m) long. The body of Dall's 
porpoises is a very dark gray or black in coloration with variable 
contrasting white thoracic panels and white `frosting' on the dorsal 
fin and tail that distinguish them from other cetacean species. These 
markings and colorations vary with geographic region and life stage, 
with adults having more distinct patterns.
    Based on NMFS stock assessment reports, Dall's porpoises within the 
Pacific U.S. Exclusive Economic Zone are divided into two discrete, 
noncontiguous areas: (1) waters off California, Oregon, and Washington, 
and (2) Alaskan waters (Carretta et al., 2008). Only individuals from 
the CA/OR/WA stock may occur within the project area.
    Status--The NMFS population estimate, recently updated in 2010 for 
the CA/OR/WA stock, is 42,000 (CV = 0.33) which is based on vessel line 
transect surveys by Barlow (2010) and Forney (2007). The minimum 
population is considered to be 32,106. Additional numbers of Dall's 
porpoises 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 due to the need for more up-to-date information. Dall's 
porpoise are not listed as depleted under the MMPA or listed under the 
ESA. The average annual human-caused mortality is estimated to be less 
than the PBR, and therefore the stock is not classified as a strategic 
stock under the MMPA. The status of Dall's porpoises in California, 
Oregon and Washington relative to OSP is not known, and there are 
insufficient data to evaluate potential trends in abundance.
    Distribution--The Dall's porpoise is found from northern Baja 
California, Mexico, north to the northern Bering Sea and south to 
southern Japan (Jefferson et al., 1993). The species is only common 
between 32-62 [deg]N in the eastern North Pacific (Morejohn, 1979; 
Houck and Jefferson, 1999). North-south movements in California, 
Oregon, and Washington have been suggested. Dall's porpoises shift 
their distribution southward during cooler-water periods (Forney and 
Barlow, 1998). Norris and Prescott (1961) reported finding Dall's 
porpoises in southern California waters only in the winter, generally 
when the water temperature was less than 15 [deg]C (59[emsp14][deg]F). 
Seasonal movements have also been noted off Oregon and Washington, 
where higher densities of Dall's porpoises were sighted offshore in 
winter and spring and inshore in summer and fall (Green et al., 1992).
    In Washington, they are most abundant in offshore waters. They are 
year-round residents in Washington (Green et al., 1992), but their 
distribution is highly variable between years, likely due to changes in 
oceanographic conditions (Forney and Barlow, 1998). Dall's porpoises 
are observed throughout the year in the Puget Sound north of Seattle 
(Osborne et al., 1998) and are seen occasionally in southern Puget 
Sound. Dall's porpoises may also occasionally occur in Hood Canal 
(Jeffries 2006, personal communication). Nearshore habitats used by 
Dall's porpoises could include the marine habitats found in the inland 
marine waters of the Hood Canal. A Dall's porpoise was observed in the 
deeper water at NBKB in summer 2008 (Tannenbaum et al., 2009a).
    Behavior and Ecology--Dall's porpoises can be opportunistic feeders 
but primarily consume schooling forage fish. They are known to eat 
squid, crustaceans, and fishes such as blackbelly eelpout (Lycodopsis 
pacifica), herring, pollock, hake, and Pacific sandlance (Ammodytes 
hexapterus) (Walker et al., 1998).

[[Page 79423]]

Groups of Dall's porpoises generally include fewer than ten individuals 
and are fluid, probably aggregating for feeding (Jefferson, 1990, 1991; 
Houck and Jefferson, 1999). Dall's porpoises become sexually mature at 
three and a half to eight years of age (Houck and Jefferson, 1999) and 
give birth to a single calf after ten to twelve months. Breeding and 
calving typically occurs in the spring and summer (Angell and Balcomb, 
1982). In the North Pacific, there is a strong summer calving peak from 
early June through August (Ferrero and Walker, 1999), and a smaller 
peak in March (Jefferson, 1989). Resident Dall's porpoises breed in 
Puget Sound from August to September.
    Acoustics--Only short duration pulsed sounds have been recorded for 
Dall's porpoises (Houck and Jefferson, 1999); this species apparently 
does not whistle often (Richardson et al., 1995). Dall's porpoises 
produce short duration (50-1,500 [mu]s), high-frequency, narrow band 
clicks, with peak energies between 120-160 kHz (Jefferson, 1988). There 
is no published data on the hearing abilities of this species.

Harbor Porpoise

    Species Description--Harbor porpoises belong to the Phocoenid 
(porpoise) family and are found extensively along the Pacific U.S. 
coast. Harbor porpoises are small, with males reaching average lengths 
of approximately 5 ft (1.5 m); Females are slightly larger with an 
average length of 5.5 ft (1.7 m). The average adult harbor porpoise 
weighs between 135-170 lb (61-77 kg). Harbor porpoises have a dark grey 
coloration on their backs, with their belly and throats white. They 
have a dark grey chin patch and intermediate shades of grey along their 
sides.
    Recent preliminary genetic analyses of samples ranging from 
Monterey, CA to Vancouver Island, BC indicate that there is small-scale 
subdivision within the U.S. portion of this range (Chivers et al., 
2002). Although geographic structure exists along an almost continuous 
distribution of harbor porpoises from California to Alaska, stock 
boundaries are difficult to draw because any rigid line is generally 
arbitrary from a biological perspective. Nevertheless, based on genetic 
data and density discontinuities identified from aerial surveys, NMFS 
identifies eight stocks in the Northeast Pacific Ocean. Pacific coast 
harbor porpoise stocks include: (1) Monterey Bay, (2) San Francisco-
Russian River, (3) northern California/southern Oregon, (4) Oregon/
Washington coastal, (5) inland Washington, (6) Southeast Alaska, (7) 
Gulf of Alaska, and (8) Bering Sea. Only individuals from the 
Washington Inland Waters stock may occur in the project area.
    Status--Aerial surveys of the inland waters of Washington and 
southern British Columbia were conducted during August of 2002 and 2003 
(J. Laake, unpubl. data). These aerial surveys included the Strait of 
Juan de Fuca, San Juan Islands, Gulf Islands, and Strait of Georgia, 
which includes waters inhabited by the Washington Inland Waters stock 
of harbor porpoises as well as harbor porpoises from British Columbia. 
An average of the 2002 and 2003 estimates of abundance in U.S. waters 
resulted in an uncorrected abundance of 3,123 (CV= 0.10) harbor 
porpoises in Washington inland waters (J. Laake, unpubl. data). When 
corrected for availability and perception bias, the estimated abundance 
for the Washington Inland Waters stock of harbor porpoise is 10,682 (CV 
= 0.38) animals (Carretta et al., 2008). The minimum population 
estimate is 7,841. Harbor porpoise are not listed as depleted under the 
MMPA or listed under the ESA. Based on currently available data, the 
total level of human-caused mortality is not known to exceed the PBR. 
Therefore, the Washington Inland Waters harbor porpoise stock is not 
classified as strategic. The status of this stock relative to its OSP 
level and population trends is unknown. Although long-term harbor 
porpoise sightings in southern Puget Sound have declined since the 
1940s, sightings have increased in Puget Sound and northern Hood Canal 
in recent years and are now considered to regularly occur year-round in 
these waters (Calambokidis 2010, pers. comm). This 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).
    Distribution--Harbor porpoises are generally found in cool 
temperate to subarctic waters over the continental shelf in both the 
North Atlantic and North Pacific (Read 1999). This species is seldom 
found in waters warmer than 17 [deg]C (63[emsp14][deg]F; Read 1999) or 
south of Point Conception (Hubbs 1960; Barlow and Hanan 1995). Harbor 
porpoises can be found year-round primarily in the shallow coastal 
waters of harbors, bays, and river mouths (Green et al., 1992). Along 
the Pacific coast, harbor porpoises occur from Monterey Bay, California 
to the Aleutian Islands and west to Japan (Reeves et al., 2002). Harbor 
porpoises are known to occur in Puget Sound year round (Osmek et al., 
1996, 1998; Carretta et al., 2007), and harbor porpoise observations in 
northern Hood Canal have increased in recent years (Calambokidis 2010, 
pers. comm.). Prior to recent construction projects conducted by the 
Navy at NBKB, harbor porpoises were considered as likely occurring only 
occasionally in the project area. A single harbor porpoise had been 
sighted in deeper water at NBKB during 2010 field observations (SAIC, 
2010). 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. Following these 
sightings, the Navy conducted dedicated line transect surveys, 
recording multiple additional sightings of harbor porpoise, and have 
revised local density estimates accordingly. The current density 
estimates are based upon a small sample size of transect surveys, and 
may be further revised as more information becomes available from 
ongoing Navy survey efforts.
    Behavior and Ecology--Harbor porpoises are non-social animals 
usually seen in small groups of two to five animals. Little is known 
about their social behavior. Harbor porpoises can be opportunistic 
foragers but primarily consume schooling forage fish (Osmek et al., 
1996; Bowen and Siniff, 1999; Reeves et al., 2002). Along the coast of 
Washington, harbor porpoises primarily feed on herring, market squid 
(Loligo opalescens) and eulachon (Thaleichthys pacificus) (Gearin et 
al., 1994). Females reach sexual maturity at three to four years of age 
and may give birth every year for several years in a row. Calves are 
born in late spring (Read, 1990; Read and Hohn, 1995). Dall's and 
harbor porpoises appear to hybridize relatively frequently in the Puget 
Sound area (Willis et al., 2004).
    Acoustics--Harbor porpoise vocalizations include clicks and pulses 
(Ketten, 1998), as well as whistle-like signals (Verboom and Kastelein 
1995). The dominant frequency range is 110-150 kHz, with source levels 
of 135-177 dB re 1 [mu]Pa-m (Ketten 1998). Echolocation signals include 
one or two low-frequency components in the 1.4-2.5 kHz range (Verboom 
and Kastelein 1995).
    A behavioral audiogram of a harbor porpoise indicated the range of 
best sensitivity is 8-32 kHz at levels between 45-50 dB re 1 [mu]Pa-m 
(Andersen 1970); however, auditory-evoked potential studies showed a 
much higher frequency of approximately 125-130 kHz (Bibikov 1992). The 
auditory-evoked potential method suggests that the harbor porpoise 
actually has two frequency ranges of best sensitivity. More recent 
psycho-acoustic studies

[[Page 79424]]

found the range of best hearing to be 16-140 kHz, with a reduced 
sensitivity around 64 kHz (Kastelein et al., 2002). Maximum sensitivity 
occurs between 100-140 kHz (Kastelein et al., 2002).

Potential Effects of the Specified Activity on Marine Mammals

    NMFS has determined that pile driving, as outlined in the project 
description, has the potential to result in behavioral harassment of 
Steller sea lions, California sea lions, harbor seals, harbor 
porpoises, Dall's porpoises, and killer whales that may be swimming, 
foraging, or resting in the project vicinity while pile driving is 
being conducted. Pile driving could potentially harass those pinnipeds 
that are in the water close to the project site, whether their heads 
are above or below the surface.

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 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.
    As mentioned previously in this document, three pinniped and three 
cetacean species are likely to occur in the proposed project area. Of 
the three cetacean species likely to occur in the project area, two are 
classified as high frequency cetaceans (Dall's and harbor porpoises) 
and one is classified as a mid-frequency cetacean (killer whales) 
(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; O'Keefe and Young, 1984; DoN, 2001b).
    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, either permanently or 
temporarily. However, this depends on both 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

[[Page 79425]]

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 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.
    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.
    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

[[Page 79426]]

that could cause TTS or the onset of PTS.

Disturbance Reactions

    Disturbance includes a variety of effects, including subtle changes 
in behavior, more conspicuous changes in activities, and displacement. 
Reactions to sound, if any, depend on species, state of maturity, 
experience, current activity, reproductive state, time of day, and many 
other factors (Richardson et al., 1995; Wartzok et al., 2004; Southall 
et al., 2007; Weilgart, 2007). Behavioral responses to sound are highly 
variable and context specific. For each potential behavioral change, 
the magnitude of the change ultimately determines the severity of the 
response. A number of factors may influence an animal's response to 
sound, including its previous experience, its auditory sensitivity, its 
biological and social status (including age and sex), and its 
behavioral state and activity at the time of exposure.
    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; Caltrans, 2001, 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. 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 (Caltrans 2001, 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

[[Page 79427]]

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 Steller sea lions, 
California sea lions, harbor seals, transient killer whales, harbor 
porpoises, and Dall's porpoises. 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 a negligible impact 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.

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 (6.2 mi), 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 (Scholik and Yan, 2001, 
2002; Govoni et al., 2003; Hawkins, 2005; Hastings, 1990, 2007; Popper 
et al., 2006; 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 (Chapman and 
Hawkins, 1969; Pearson et al., 1992; Skalski et al., 1992). SPLs of 
sufficient strength have been known to cause injury to fish and fish 
mortality (Caltrans, 2001; Longmuir and Lively, 2001). 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

    In addition, the area likely impacted by the wharf construction 
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, NMFS 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).
    The modeling results for zones of influence (ZOIs; see ``Estimated 
Take by

[[Page 79428]]

Incidental Harassment'') 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 the ZOIs vary between the 
different diameter piles and types of installation methods, the Navy is 
proposing to establish mitigation zones for the maximum zone of 
influence 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 of the U.S. 
Environmental Protection Agency 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 (33 ft), 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.

Shutdown and Buffer Zone

    The following measures would apply to the Navy's mitigation through 
shutdown and buffer zones:
    (a) The Navy would implement a minimum shutdown zone of 25 m (82 
ft) radius for cetaceans and 10 m for pinnipeds around all pile driving 
activity. Shutdown zones typically include all areas where the 
underwater SPLs are anticipated to equal or exceed the Level A (injury) 
harassment criteria for marine mammals (180-dB isopleth for cetaceans; 
190-dB isopleth for pinnipeds). In this case, pile driving sounds are 
expected to attenuate below 180 dB at distances of 22 m (72 ft) or less 
and below 190 dB at distances of 5 m (16 ft) or less, but the minimum 
shutdown zones are intended to further avoid the risk of direct 
interaction between marine mammals and the equipment.
    (b) The calculated zone encompassing the full 120-dB buffer zone 
for vibratory pile driving (an effective area of 41.4 km\2\ when 
attenuation due to landmasses is accounted for) is so large as to make 
monitoring impracticable. As described previously, the buffer zone 
corresponding to the 160-dB harassment criterion for impact pile 
driving would always be subsumed by the larger zone associated with 
concurrently operating vibratory pile drivers. In order to conduct 
monitoring additional to the monitoring conducted in support of the 
shutdown zones, the Navy would establish an observation position within 
the Waterfront Restricted Area, maximally distant from the pile driving 
operations. Any marine mammal observations would be relayed to the 
observers monitoring the shutdown zones and would be recorded as Level 
B takes. The additional position would be able to monitor an effective 
area of at least 500 m distance from the pile driving activity, and any 
sighted animals would be recorded as takes. However, with such a large 
action area, it is impossible to guarantee that all animals would be 
observed or to make comprehensive observations of fine-scale behavioral 
reactions to sound.
    (c) The shutdown and buffer zones would be monitored throughout the 
time required to drive a pile. If a marine mammal is observed within 
the buffer zone, a take would be recorded and behaviors documented. 
However, 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.
    (d) All buffer and shutdown zones would initially be based on the 
distances from the source that are predicted for each threshold level. 
However, in-situ acoustic monitoring would be utilized to determine the 
actual distances to these threshold zones, and the size of the shutdown 
and buffer zones would be adjusted accordingly based on received SPLs.

Visual Monitoring

    Monitoring would be conducted for a minimum 10 m or 25 m shutdown 
zone (for pinnipeds and cetaceans, respectively) and an approximate 500 
m (1,640 ft) buffer zone surrounding each pile for the presence of 
marine mammals before, during, and after pile driving activities. The 
buffer zone was set at the largest area practicable for the Navy to 
maintain a monitoring presence over the duration of the activity. 
Sightings occurring outside this area (within the predicted 41.4 km\2\ 
buffer zone predicted for the 120-dB isopleths) would still be recorded 
and noted as a take, but detailed observations outside this zone would 
not be possible, and it would be impossible for the Navy to account for 
all individuals occurring in such a zone with any degree of certainty. 
Monitoring would take place from 15 minutes prior to initiation through 
30 minutes post-completion of pile driving activities.
    The following additional measures would apply to visual monitoring:
    (a) Monitoring would be conducted by qualified observers. A trained 
observer would be placed from the best vantage point(s) practicable 
(e.g., from a small boat, the pile driving barge, on shore, or any 
other suitable location) to monitor for marine mammals and implement 
shut-down or delay procedures when applicable by calling for the shut-
down to the hammer operator.
    (b) Prior to the start of pile driving activity, the shut-down zone 
would be monitored for 15 minutes to ensure that it is clear of marine 
mammals. Pile driving would only commence once observers have declared 
the shut-down zone clear of marine mammals; animals would be allowed to 
remain in the buffer zone (i.e., must leave of their own volition) and 
their behavior would be monitored and documented.
    (c) If a marine mammal approaches or enters the shut-down zone 
during the course of pile driving operations, pile driving would be 
halted and delayed until either the animal has voluntarily left and 
been visually confirmed beyond the shut-down zone or 15 minutes have 
passed without re-detection of the animal.

Sound Attenuation Devices

    Sound attenuation devices would be utilized during all impact pile 
driving operations. Impact pile driving is only expected to be required 
to proof, or drive the last 10-15 ft (3-4.6 m) of select piles. Past 
experience has shown that proofing is rarely required at the project 
location. The Navy plans to use a bubble curtain as mitigation for in-
water sound during construction activities. Bubble curtains absorb 
sound, attenuate pressure waves, exclude marine life from work areas, 
and control the

[[Page 79429]]

migration of debris, sediments and process fluids.

Acoustic Measurements

    Acoustic measurements would be used to empirically verify the 
proposed shut-down and buffer zones. For further detail regarding the 
Navy's acoustic monitoring plan see ``Proposed Monitoring and 
Reporting''.

Timing Restrictions

    The Navy has set timing restrictions for pile driving activities to 
avoid in-water work when ESA-listed fish populations are most likely to 
be present. The in-water work window for avoiding negative impacts to 
fish species 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.

Soft Start

    The use of a soft-start procedure is believed to provide additional 
protection to marine mammals by warning, or providing marine mammals a 
chance to leave the area prior to the hammer operating at full 
capacity. The wharf construction project would utilize soft-start 
techniques (ramp-up and dry fire) for impact and vibratory pile 
driving. The soft-start requires contractors to initiate sound from 
vibratory hammers for fifteen seconds at reduced energy followed by a 
30-second waiting period. This procedure would be repeated two 
additional times. For impact driving, contractors would be required to 
provide an initial set of three strikes from the impact hammer at forty 
percent energy, followed by a 30-second waiting period, then two 
subsequent three strike sets.

Daylight Construction

    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. Vibratory pile driving and other construction activities 
occurring in the water between July 16 and September 15 could occur 
during daylight hours (sunrise to sunset). Between September 16 and 
February 15, construction activities occurring in the water would occur 
during daylight hours (sunrise to sunset).

Mitigation Effectiveness

    It should be recognized that although marine mammals would be 
protected from Level A harassment by the utilization of a bubble 
curtain and protected species observers (PSOs) monitoring the near-
field injury zones, mitigation may not be 100 percent effective at all 
times in locating marine mammals in the buffer zone. The efficacy of 
visual detection depends on several factors including the observer's 
ability to detect the animal, the environmental conditions (visibility 
and sea state), and monitoring platforms.
    All observers utilized for mitigation activities would be 
experienced biologists with training in marine mammal detection and 
behavior. Due to their specialized training the Navy expects that 
visual mitigation would be highly effective. Trained observers have 
specific knowledge of marine mammal physiology, behavior, and life 
history, which may improve their ability to detect individuals or help 
determine if observed animals are exhibiting behavioral reactions to 
construction activities.
    The Puget Sound region, including the Hood Canal, only infrequently 
experiences winds with velocities in excess of 25 kn (Morris et al., 
2008). The typically light winds afforded by the surrounding highlands 
coupled with the fetch-limited environment of the Hood Canal result in 
relatively calm wind and sea conditions throughout most of the year. 
The wharf construction project site has a maximum fetch of 8.4 mi (13.5 
km) to the north, and 4.2 mi (6.8 km) to the south, resulting in 
maximum wave heights of from 2.85-5.1 ft (0.9-1.6 m) (Beaufort Sea 
State (BSS) between two and four), even in extreme conditions (30 kt 
winds) (CERC, 1984). Visual detection conditions are considered optimal 
in BSS conditions of three or less, which align with the conditions 
that should be expected for the wharf construction project at NBKB.

Habitat Mitigation

    In addition to mitigation measures developed specifically for 
marine mammals and described previously, the following compensatory 
mitigation measures would be implemented to restore marine fish 
habitats, and by extension to indirectly benefit marine mammals in the 
project area. These measures were not developed in consultation with 
NMFS, but are described here due to their potential benefit for marine 
mammals.
    Compensatory Mitigation--Compensatory Mitigation is the term given 
to projects or plans undertaken to offset unavoidable adverse 
environmental impacts which remain after all appropriate and 
practicable avoidance and minimization has been achieved. Compensatory 
Mitigation involves actions taken to offset unavoidable adverse impacts 
to wetlands, streams, and other aquatic resources. For impacts 
authorized under a Clean Water Act Section 404 permit, Compensatory 
Mitigation is not considered until after all appropriate and 
practicable steps have been taken to first avoid and then minimize 
adverse impacts to the aquatic ecosystem pursuant to 40 CFR part 230 
(i.e., the Clean Water Act Section 404(b)(1) Guidelines). Compensatory 
Mitigation is required for permits authorized by the Clean Water Act 
Section 404 and other Department of the Army permits.
    The Compensatory Mitigation Rule establishes a hierarchy for 
Compensatory Mitigation:
     Mitigation Banks
     In-Lieu Fee (ILF) Programs
     Permittee-Responsible Mitigation
    A preference for mitigation banks is established at present. 
However, there are no established mitigation banks or ILF programs for 
Kitsap County or the Hood Canal. Therefore, the Navy`s preference for 
providing mitigation and complying with the Compensatory Mitigation 
Rule is through the development of an ILF Program. The goal of the ILF 
Program is to ensure no net loss of nearshore aquatic resource 
functions by in-kind mitigation within Kitsap County and/or Hood Canal. 
The Navy would partner with a qualified ILF sponsor that would be 
responsible for preparing all documentation associated with 
establishment of the program, including a prospectus, a credit/debit 
calculation tool or instrument, mitigation plans, and other appropriate 
documents. The ILF sponsor would be responsible for performing all of 
the required functions of the program including fiscal management; 
agreement(s) with entities that will purchase and hold mitigation sites 
in conservation status in perpetuity; reporting; and contracting for 
the design, construction, and monitoring for specific mitigation 
projects.
    The Navy anticipates that the Kitsap County Nearshore Habitat 
Assessment and Restoration Prioritization Framework could provide an 
assessment tool to identify and prioritize mitigation sites. As the ILF 
program is developed for Kitsap County and/or Hood Canal, a more 
detailed credit/debit calculation tool or instrument would be 
developed. This information would be developed and reviewed in 
conjunction with the development of the ILF program. Mitigation can 
include protection, restoration, enhancement, and/or creation. The 
mitigation strategy selected will be based on an assessment of type and 
degree of disturbance at the

[[Page 79430]]

landscape, drift cell, and nearshore assessment unit (NAU) scales.
    Priority would be given to mitigation strategies that augment 
regional and local watershed plans and goals. Such strategies include, 
but are not limited to, protection and restoration of critical resource 
areas through acquisition or conservation easements, reconnecting 
pocket estuaries to tidal fluxes, shoreline rehabilitation, removal of 
fish migration barriers, stream restoration, and reforestation of 
watersheds and marine/freshwater riparian zones.
    Alternative Mitigation Strategies--In the event that an ILF program 
is not established in Kitsap County in time for use as mitigation for 
the proposed action, other mitigation options will be considered. As an 
alternative to pursuing the development of an ILF program for Kitsap 
County/and or Hood Canal, the Navy is currently assessing nearshore 
permittee responsible mitigation opportunities within the Hood Canal 
and Puget Sound with state and local agencies and tribes. The Navy 
would identify appropriate in-kind mitigation sufficient in size to 
ensure no net loss of aquatic resource functions. Strategies to effect 
no net loss could include a combination of restoration, enhancement, 
creation, and preservation of nearshore habitats. Potential nearshore 
mitigation sites will take into consideration state and local watershed 
management plans, property ownership, tribal usual and accustomed 
areas, likelihood of success, ability to address multiple functions and 
services both among and within aquatic habitat types, and the ability 
to affect or improve regional aquatic resource conservation 
initiatives. As with the proposed development of an ILF program, these 
potential permittee-responsible mitigation projects would also be 
reviewed in accordance with the Compensatory Mitigation Rule and would 
be submitted for review and approval as part of the application 
process. In the event that the Navy selects a permittee-responsible 
mitigation as the Compensatory Mitigation strategy, a mitigation plan 
would be submitted to the U.S. Army Corps of Engineers.
    NMFS has carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that NMFS prescribes 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 by NMFS, NMFS has 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 NMFS 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.

Acoustic Measurements

    Within the first 30 days of pile driving, the Navy would capture a 
representative acoustic sample of the major pile driving scenarios 
under the modeled conditions (impact hammer and vibratory driving, 
smaller [24-in to 36-in] and larger [48-in] piles, plumb and batter 
piles). All measurements would be made with the sound attenuation 
measures discussed previously in place. These acoustic measurements 
would determine the actual distances to the following isopleths: 190 dB 
re 1[mu]Pa rms, 180 dB re 1[mu]Pa rms, and 160 dB re 1[mu]Pa rms. The 
Navy would also conduct underwater acoustic monitoring for vibratory 
pile driving to determine the actual distance to the 120 dB re 1[mu]Pa 
rms isopleth for marine mammal behavioral harassment relative to 
background levels. Maximum sound pressure levels would also be 
documented. Airborne acoustic monitoring would be conducted during 
impact and vibratory pile driving to identify the actual distance to 
the 90 dB re 20[mu]Pa rms, and 100 dB re 20[mu]Pa rms airborne 
isopleths.
    At a minimum, the methodology would include:
     For underwater recordings, a stationary hydrophone system 
with the ability to measure SPLs at mid-water depth and approximately 1 
m from the bottom, (taking tidal changes into account) would be placed 
at a distance of 10 m from the source. The hydrophone would be deployed 
so as to maintain a constant distance of 10 m from the pile.
     For airborne recordings, reference recordings would be 
attempted at approximately 50 ft (15.2 m) from the source via a 
stationary hydrophone. However, other distances may be utilized to 
obtain better data if the pile driving signal cannot be isolated 
clearly due to other sound sources (e.g., barges or generators).
     Each hydrophone (underwater) and microphone (airborne) 
would be calibrated prior to the start of the action and would be 
checked at the beginning of each day of monitoring activity. Other 
hydrophones and microphones would be placed at other distances and/or 
depths and moved as necessary to determine the distance to the 
thresholds for marine mammals (these include peak, rms, and SEL for 
underwater sound, and unweighted for airborne sound).
     Unweighted ambient conditions, both airborne and 
underwater, would be measured and recorded for 30 to 60 s each hour, 
every day for one week during the first 30 days of the construction 
period to determine background sound levels. These measurements are 
intended to capture ambient background sound during the timeframe of 
construction, but in the absence of pile driving sound. Ambient sound 
recordings would be edited for anomalous data to provide the best 
possible baseline condition for background sound. Recording would be 
made in the 10 Hz to 20 kHz range.
     Airborne levels would be recorded as an unweighted time 
series. The distance to marine mammal airborne sound disturbance 
thresholds would be determined.
     Sound levels associated with the soft-start techniques (on 
a representative subset of piles) would also be measured.
     Environmental data would be collected, such as wind speed 
and direction, wave height, precipitation, presence and location of 
other vessels, and types and locations of in-water construction 
activities, as well as other factors that could contribute to 
influencing the airborne and underwater sound levels (e.g., aircraft, 
boats).

[[Page 79431]]

     The construction contractor would supply the Navy and 
other relevant monitoring personnel the substrate composition, hammer 
model and size, hammer energy settings and any changes to those 
settings during hammering of the piles being monitored, depth of the 
pile being driven, and blows per foot for the piles monitored.
     Post-analysis of underwater sound level signals would 
include the average rms value across all pile strikes per pile, the 
rise time, average duration of each pile strike, and number of strikes 
per pile, as well as a frequency spectrum with mitigation, between 10 
and 20,000 Hz, for up to eight successive strikes with similar sound 
levels. Rms analyses would be completed for vibratory driving, 
including presentation of representative frequency spectra.
     Post-analysis of airborne sound would be presented in an 
unweighted format, and would include presentation of the average rms 
value across all pile strikes per pile, and the average rms value for 
vibratory driving. Frequency spectra would be provided from 10 to 
20,000 Hz for up to eight successive strikes with similar sound levels, 
and would also be provided for representative vibratory driving.

Visual Marine Mammal Observations

    The Navy would 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 would be trained 
in marine mammal identification and behaviors. NMFS requires that the 
observers have no other construction-related tasks while conducting 
monitoring.
    Methods of Monitoring--The Navy would monitor the shutdown zone and 
buffer zone before, during, and after pile driving. There would, at all 
times, be at least one observer stationed at an appropriate vantage 
point to observe the shutdown zones associated with each operating 
hammer. There would also at all times be at least one vessel-based 
observer stationed within the WRA. In addition, at least one marine 
mammal observer would be stationed on a vessel conducting acoustic 
monitoring outside the WRA, for as long as such monitoring is 
conducted. The Navy estimates that representative acoustic sampling may 
occur in approximately 30 days. Based on NMFS requirements, the Marine 
Mammal Monitoring Plan would include the following procedures for pile 
driving:
    (1) MMOs would be located at the best vantage point(s) in order to 
properly see the entire shutdown zone and as much of the buffer zone as 
possible. This may require the use of a small boat to monitor certain 
areas while also monitoring from one or more land based vantage points.
    (2) During all observation periods, observers would use binoculars 
and the naked eye to search continuously for marine mammals.
    (3) If the shut down or buffer zones are obscured by fog or poor 
lighting conditions, pile driving at that location would not be 
initiated until that zone is visible.
    (4) The shut down and buffer zones around the pile would be 
monitored for the presence of marine mammals before, during, and after 
any pile driving or removal activity.
    Pre-Activity Monitoring--The shutdown and buffer zones would be 
monitored for 15 minutes prior to initiating the soft start for pile 
driving. If marine mammal(s) are present within the shut down zone 
prior to pile driving, or during the soft start, the start of pile 
driving would be delayed until the animal(s) leave the shut down zone. 
Pile driving would resume only after the PSO has determined, through 
sighting or by waiting 15 minutes, that the animal(s) has moved outside 
the shutdown zone.
    During Activity Monitoring--The shutdown and buffer zones would 
also be monitored throughout the time required to drive or remove a 
pile. If a marine mammal is observed entering the buffer zone, a take 
would be recorded and behaviors documented. However, that pile segment 
would be completed without cessation, unless the animal enters or 
approaches the shut down zone, at which point all pile driving 
activities would be halted. Pile driving can only resume once the 
animal has left the shutdown zone of its own volition or has not been 
re-sighted for a period of 15 minutes.
    Post-Activity Monitoring--Monitoring of the shutdown and buffer 
zones would continue for 30 minutes following the completion of pile 
driving.
    Individuals implementing the monitoring protocol would assess its 
effectiveness using an adaptive approach. Monitoring biologists would 
use their best professional judgment throughout implementation and 
would seek improvements to these methods when deemed appropriate. Any 
modifications to protocol would be coordinated between the Navy and 
NMFS.

Data Collection

    NMFS requires that the PSOs use NMFS-approved sighting forms. In 
addition to the following requirements, the Navy would note in their 
behavioral observations whether an animal remains in the project area 
following a Level B taking (which would not require cessation of 
activity). This information would ideally make it possible to determine 
whether individuals are taken (within the same day) by one or more 
types of pile driving (i.e., impact and vibratory). NMFS requires that, 
at a minimum, the following information be collected on the sighting 
forms:
    (1) Date and time that pile driving begins or ends;
    (2) Construction activities occurring during each observation 
period;
    (3) Weather parameters identified in the acoustic monitoring (e.g., 
percent cover, visibility);
    (4) Water conditions (e.g., sea state, tide state);
    (5) Species, numbers, and, if possible, sex and age class of marine 
mammals;
    (6) Marine mammal behavior patterns observed, including bearing and 
direction of travel, and if possible, the correlation to SPLs;
    (7) Distance from pile driving activities to marine mammals and 
distance from the marine mammals to the observation point;
    (8) Locations of all marine mammal observations; and
    (9) Other human activity in the area.

Reporting

    A draft report would be submitted to NMFS within 60 days of the 
completion of the first 30 days of acoustic measurements and marine 
mammal monitoring. The results would be summarized in graphical form 
and include summary statistics and time histories of impact sound 
values for each pile. The report would also provide descriptions of any 
problems encountered in deploying sound attenuating devices, any 
adverse responses to construction activities by marine mammals, and 
actions taken to solve these problems. A final report would be prepared 
and submitted to NMFS within 30 days following receipt of comments on 
the draft report from NMFS. Within 60 days of the end of the in-water 
work period, a draft comprehensive report on all marine mammal 
monitoring conducted under the proposed IHA would be submitted to NMFS. 
The report would include marine mammal observations pre-activity, 
during-activity, and post-activity during pile driving days. A final 
report would be prepared and submitted to NMFS within 30 days following 
receipt of comments on the draft report from NMFS. At a minimum, the 
report would include:
    (1) Date and time of activity;

[[Page 79432]]

    (2) Water and weather conditions (e.g., sea state, tide state, 
percent cover, visibility);
    (3) Physical characteristics of the bottom substrate where piles 
are driven;
    (4) Description of the pile driving activity (e.g., size and type 
of piles);
    (5) A detailed description of the sound attenuation device, 
including design specifications;
    (6) The impact or vibratory hammer force used to drive or extract 
the piles;
    (7) A description of the monitoring equipment;
    (8) The distance between hydrophone(s) and pile;
    (9) The depth of the hydrophone(s);
    (10) The depth of water in which the pile was driven;
    (11) The depth into the substrate that the pile was driven;
    (12) The ranges and means for peak, rms, and SELs for each pile;
    (13) The results of the acoustic measurements, including the 
frequency spectrum, peak and rms SPLs, and single-strike and cumulative 
SEL with and without the attenuation system;
    (14) The results of the airborne sound measurements (unweighted 
levels);
    (15) A description of any observable marine mammal behavior in the 
immediate area and, if possible, the correlation to underwater sound 
levels occurring at that time;
    (16) Actions performed to minimize impacts to marine mammals;
    (17) Times when pile driving is stopped due to presence of marine 
mammals within shut down zones and time when pile driving resumes;
    (18) Results, including the detectability of marine mammals, 
species and numbers observed, sighting rates and distances, behavioral 
reactions within and outside of shut down zones; and
    (19) A refined take estimate based on the number of marine mammals 
observed in the shut down and buffer zones.

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 remote. 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 taken. 
For example, during the past ten years, 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.
    The proposed 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 the proposed activities are expected to affect 
only a relatively small number 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 is requesting authorization for the potential 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

    For all species, the best scientific information available was used 
to construct density estimates or estimate local abundance. Of 
available information deemed suitable for use, the data that produced 
the most conservative (i.e., highest) density or abundance estimate for 
each species was used. 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. These consist 
of three discrete sets of survey effort, and are described here in 
greater detail.
    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 (average fourteen per 
month) although without a formal survey protocol. During the surveys, 
staff visited each of the above-mentioned locations and recorded

[[Page 79433]]

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. Thus, NMFS has not used these data to 
derive a density but rather has used the absolute abundance to estimate 
take. Data were compiled for the period from April 2008 through June 
2010 for analysis in this proposed IHA, and these data provided 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).
    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 (91 m), 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 produced the information used to 
estimate take for Dall's porpoise, as well as for harbor porpoise under 
previous Navy actions at NBKB.
    Recently, as part of the Test Pile Program, marine mammal 
monitoring was conducted on construction days for mitigation purposes. 
During those efforts, the Navy observed that harbor porpoises were more 
common in deeper waters of Hood Canal than the previously described, 
nearshore vessel-based surveys indicated. For that reason, the Navy 
conducted vessel-based line transect surveys in Hood Canal on days 
where no pile driving activities occurred in order to collect 
additional density data for species present in Hood Canal. These 
surveys were primarily conducted in September and 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 (see Figures 2-1 and 4-1 in the 
Navy's application). 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. Due to the recent 
execution of these surveys, not all data have been processed. Due to 
the unexpected abundance of harbor porpoises encountered during the 
Test Pile Program, data for this species were processed first and are 
available for use in this proposed IHA. All other species data may be 
included in subsequent environmental compliance documents once all 
post-processing is complete, but preliminary analysis indicates that 
use of the previously described data would still provide the most 
conservative take estimates for the other species.
    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. 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, as 
discussed in preceding sections. 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:
    (a) All pilings to be installed would have a sound disturbance 
distance equal to that of the piling that causes the greatest sound 
disturbance (i.e., the piling furthest from shore);
    (b) Mitigation measures (e.g., sound attenuation system) would be 
utilized, as discussed previously;
    (c) All marine mammal individuals potentially available are assumed 
to be present within the relevant area, and thus incidentally taken; 
and,
    (d) An individual can only be taken once during a 24-h period.
    The calculation for marine mammal takes is estimated by:
    Take estimate = (n * ZOI) * days of total activity

Where:
n = density estimate used for each species/season
ZOI = sound threshold zone of influence (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 (actual) specified in Table 5 were used to 
calculate ZOI around each pile. All impact pile driving take 
calculations were based on the estimated threshold ranges using a 
bubble curtain with 10 dB attenuation as a mitigation measure (see 
``Underwater Sound from Piledriving''). 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

[[Page 79434]]

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.
    For sea lions, as described previously, the surveys offering the 
most conservative estimates of abundance do not have a defined survey 
area and so are not suitable for deriving a density construct. Instead, 
abundance is estimated on the basis of previously described 
opportunistic sighting information at the NBKB waterfront, and it is 
assumed that the total amount of animals known from NBKB haul-outs 
would be `available' to be taken in a given pile driving day. Thus, for 
these two species, take is estimated by multiplying abundance by days 
of activity.
    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 is actually spent pile driving. On days when pile 
driving occurs, it could take place for thirty minutes, or up to 
several hours. For each pile installed, vibratory pile driving is 
expected to be no more than one hour. The impact driving portion of the 
project is anticipated to take approximately fifteen minutes per pile 
(for proofing). Based on the proposed action, the total pile driving 
time from vibratory pile driving during installation would be a maximum 
of 195 days (approximately the number of days available during the in-
water work window, when considering contractor work schedule). During 
installation, there is the potential for the contractor to need to 
utilize an impact hammer to proof a select number of piles, although 
past repairs on the existing pier have never required the use of an 
impact pile driver.
    The exposure assessment methodology is an estimate of the numbers 
of individuals exposed to the effects of pile driving activities 
exceeding NMFS-established thresholds. Of note in these exposure 
estimates, mitigation methods other than the use of a sound attenuation 
device (i.e., visual monitoring and the use of shutdown zones) were not 
quantified within the assessment and successful implementation of this 
mitigation is not reflected in exposure estimates. Results from 
acoustic impact exposure assessments should be regarded as conservative 
estimates.

California Sea Lion

    California sea lions are present in Hood Canal during much of the 
year with the exception of mid-June through August. California sea 
lions occur regularly in the vicinity of the project site from 
September through mid-June, as determined by Navy waterfront surveys 
conducted from April 2008 through June 2010 (Navy 2010; Table 8). 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 have rarely been 
reported, either hauled out or swimming, elsewhere in Hood Canal 
(Jeffries 2007, personal communication). Abundance is calculated as the 
monthly average of the maximum number observed in a given month, as 
opposed to the overall average (Table 8). For example, in the month of 
May, the maximum number of animals observed on any one day was 25 in 
2008, 33 in 2009, and 17 in 2010, providing a monthly average of the 
maximum daily number observed of 25. This provides a conservative 
overall daily abundance of 26.2 for the in-water work window, as 
compared with an actual per survey abundance of 11.4 during the same 
period.
    In previous IHAs issued to the Navy for work at NBKB, NMFS has 
calculated a density for California sea lions on the basis of the 
maximum daily average number of animals for the period of activity and 
the total project area (defined as 41.4 km\2\). This approach was 
determined to be the most appropriate method of deriving a local 
density for the species (see, e.g., 76 FR 6406). The method produced a 
similar estimate of take as would be produced through the use of 
abundance information and days of activity, because the density was 
based on the same area as the larger ZOI associated with the 120-dB 
harassment zone (i.e., 41.4 km\2\), described previously, but also 
allowed for calculation of take estimate for different areas, as would 
be encompassed by the 160-dB underwater harassment zone associated with 
impact driving or harassment zones associated with airborne sound. 
However, because the vibratory and impact pile drivers would be 
operating simultaneously under the currently proposed action, the 160-
dB harassment zone associated with the impact driver would be at all 
times subsumed by the 120-dB harassment zone associated with the 
vibratory driver. In addition, because California sea lions are known 
to haul-out only in the vicinity of Delta Pier, over one mile south of 
the project area, they would not be subject to airborne sound that 
would constitute harassment (i.e., within approximately 350 m of an 
impact-driven pile). As such, NMFS has determined that it is 
appropriate to discard the previously used density construct in favor 
of simple abundance. This methodology conservatively uses the maximum 
abundance (rather than mean) and assumes that all individuals would be 
taken on any given day of activity. NMFS feels that this provides a 
conservative estimate of the number of individuals that may be 
incidentally taken by the Navy's proposed action while avoiding the 
need to construct a density estimate from survey data with no defined 
survey area. As described previously, sighting information from other 
Navy survey effort that is more appropriate for estimating density 
(i.e., with defined survey area) would produce a less conservative 
(i.e., lower) estimate of take.

                Table 8--California Sea Lion Sighting Information From NBKB, April 2008-June 2010
----------------------------------------------------------------------------------------------------------------
                                                           Number of
               Month                    Number of         surveys with       Frequency of        Abundance \2\
                                         surveys        animals present      presence \1\
----------------------------------------------------------------------------------------------------------------
January...........................                 25                 15                0.60                24.0
February..........................                 28                 24                0.86                31.0
March.............................                 28                 26                0.93                38.5
April.............................                 38                 27                0.71                36.3
May...............................                 44                 34                0.77                25.0
June..............................                 44                  7                0.16                 5.3
July..............................                 31                  0                0                    0
August............................                 29                  1                0.03                 0.5
September.........................                 26                  9                0.35                22.0

[[Page 79435]]

 
October...........................                 26                 22                0.85                45.5
November..........................                 22                 22                1                   54.0
December..........................                 24                 14                0.58                32.5
                                   -----------------------------------------------------------------------------
    Total or average (in-water                    211                107                0.53                26.2
     work season only)............
----------------------------------------------------------------------------------------------------------------
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.

    The largest observed number of California sea lions hauled out 
along the NBKB waterfront was 58 in a November survey. During the in-
water construction period (mid-July to mid-February) the largest daily 
attendance average for each month ranged from 24 individuals to 54 
individuals. The likelihood of California sea lions being present at 
NBKB is greatest from October through May, when the frequency of 
attendance in surveys was at least 0.58. Attendance along the NBKB 
waterfront in November surveys (2008-09) was 100 percent. Additionally, 
five navigational buoys near the entrance to Hood Canal were documented 
as potential haul-outs, each capable of supporting three adult 
California sea lions (Jeffries et al., 2000). Breeding rookeries are in 
California; therefore, pups are not expected to be present in Hood 
Canal (NMFS 2008b). Female California sea lions are rarely observed 
north of the California/Oregon border; therefore, only adult and sub-
adult males are expected to be exposed to project impacts. Table 10 
depicts the estimated number of behavioral harassments.

Steller Sea Lion

    Steller sea lions were first documented at the NBKB waterfront in 
November 2008, while hauled out on submarines at Delta Pier 
(Bhuthimethee, 2008, pers. comm.; Navy, 2010) and have been 
periodically observed 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 November through April (Table 9). 
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 
in November 2009.

                 Table 9--Steller Sea Lion Sighting Information From NBKB, April 2008-June 2010
----------------------------------------------------------------------------------------------------------------
                                                           Number of
               Month                    Number of         surveys with       Frequency of        Abundance \2\
                                         surveys        animals present      presence \1\
----------------------------------------------------------------------------------------------------------------
January...........................                 25                  4                0.16                 1.0
February..........................                 28                  1                0.04                 0.5
March.............................                 28                  4                0.14                 1.0
April.............................                 38                  5                0.13                 1.3
May...............................                 44                  0                0                    0
June..............................                 44                  0                0                    0
July..............................                 31                  0                0                    0
August............................                 29                  0                0                    0
September.........................                 26                  0                0                    0
October...........................                 26                  0                0                \3\ 1.3
November..........................                 22                  3                0.14                 5.0
December..........................                 24                  5                0.21                 1.5
                                   -----------------------------------------------------------------------------
    Total or average (in-water                    211                 13                0.07                 1.2
     work season only)............
----------------------------------------------------------------------------------------------------------------
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.
\3\ Abundance updated to include observations made in October 2011 during Navy's Test Pile Program. All other
  information reflects only data from April 2008-June 2010.


[[Page 79436]]

    Their frequency of occurrence by month has not exceeded 0.21 (in 
December 2009), i.e., they were present in only 21 percent of surveys 
that month. The time period from November through April coincides with 
the time when Steller sea lions are frequently observed in Puget Sound. 
Only adult and sub-adult males are likely to be present in the project 
area during this time; female Steller sea lions have not been observed 
in the project area. Since there are no known breeding rookeries in the 
vicinity of the project site, Steller sea lion pups are not expected to 
be present. By May, most Steller sea lions have left inland waters and 
returned to their rookeries to mate. Although sub-adult individuals 
(immature or pre-breeding animals) will occasionally remain in Puget 
Sound over the summer, observational data (Table 9) have indicated that 
Steller sea lions are present only from November through April and not 
during the summer months. However, recent observational data available 
from the Navy's Test Pile Program noted the presence of Steller sea 
lions at NBKB in October for the first time. Up to four individuals 
were sighted either hauled out at the submarines docked at Delta Pier 
or swimming in the waters just adjacent to those haul-outs.
    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 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

    Harbor seals are the most abundant marine mammal in Hood Canal, 
where they can occur anywhere in Hood Canal waters year-round. The Navy 
detected harbor seals during marine mammal boat surveys of the 
waterfront area from July to September 2008 (Tannenbaum et al., 2009) 
and November to May 2010 (Tannenbaum et al., 2011), as described 
previously. Harbor seals were sighted during every survey and were 
found in all marine habitats including nearshore waters and deeper 
water, and hauled out on manmade objects such as piers and buoys. 
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 are not 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 at Quilcene, Dosewallips, 
Duckabush, Hamma Hamma, and Skokomish River mouths, with the closest 
haul-out area to the project area being 10 mi (16 km) southwest of NBKB 
at Dosewallips River mouth (London, 2006). Please see Figure 4-1 of the 
Navy's application for a map of haul-out locations in relation to the 
project area.
    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 (291 km\2\ [112 
mi\2\]) and the formula presented previously.
    NMFS recognizes 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 from July-October 2011 in the same project 
area has indicated that this density provides an appropriate estimate 
of potential exposures. Data from those monitoring efforts are 
currently in post-processing and are not available in report form at 
this time. However, the density of harbor seals calculated in this 
manner (1.3 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).
    The Navy's waterfront surveys have found that it is extremely rare 
for harbor seals to haul out in the vicinity of the project area, 
although it has been known to occur. Therefore, in order to estimate 
potential incidental take of harbor seals by airborne sound, NMFS has 
considered that the entire in-water density, as described previously, 
could potentially be available to be taken by airborne sound. This 
calculation, using the density estimate as described above and the 
maximum area estimated to be ensonified to 90 dB by airborne sound 
(0.41 km\2\), results in a prediction that 0.5 seals could be exposed 
per day. When rounded up to the nearest whole number, this gives the 
result that up to one seal could haul-out within the 90-dB in-air 
harassment zone per day of pile driving. NMFS feels that this is 
extremely unlikely, based on past observations of the frequency with 
which harbor seals haul-out on the floating security fence near the 
project area, but that this is nevertheless an appropriate 
precautionary approach. Table 10 depicts the number of estimated 
behavioral harassments.

Killer Whales

    Transient killer whales are uncommon visitors to Hood Canal. 
Transients may be present in the Hood Canal anytime during the year and 
traverse as far as the project site. Resident killer whales have not 
been observed in Hood Canal, but transient pods (six to eleven 
individuals per event) were observed in Hood Canal for

[[Page 79437]]

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. 
Subsequent aerial surveys suggest that there has not been a sharp 
decline in the local seal population from these sustained feeding 
events (London 2006). Based on this data, the density for transient 
killer whales in the Hood Canal for January to June is 0.038/km\2\ 
(eleven individuals divided by the area of the Hood Canal [291 km\2\]). 
Because the timeframe of known transient killer whale occurrence in 
Hood Canal only partially overlaps the construction period (January to 
mid-February), the days of total activity (or days of potential 
exposure) portion of the formula presented previously is reduced to 45 
for killer whales. Table 10 depicts the number of estimated behavioral 
harassments.

Dall's Porpoise

    Dall's porpoises may be present in the Hood Canal year-round and 
could occur as far as the project site. Their use of inland Washington 
waters, however, is mostly limited to the Strait of Juan de Fuca. The 
Navy conducted vessel-based surveys of the waterfront area in 2008-10 
(Tannenbaum et al., 2009, 2011). During one of the surveys a Dall's 
porpoise was sighted in August in the deeper waters off Carlson Spit.
    In the absence of an abundance estimate for the entire Hood Canal, 
a density was derived from the waterfront survey by the number of 
individuals seen divided by total number of kilometers of survey effort 
(18 surveys with approximately 3.9 km\2\ [1.5 mi\2\] of effort each), 
assuming strip transect surveys. In absence of any other survey data 
for the Hood Canal, this density is assumed to be throughout the 
project area. Exposures were calculated using the formula presented 
previously. Table 10 depicts the number of estimated behavioral 
harassments.

Harbor Porpoise

    Harbor porpoises may be present in the Hood Canal year-round; their 
presence had previously been considered rare. During waterfront surveys 
of NBKB nearshore waters from 2008-10 only one harbor porpoise had been 
seen in 18 surveys of 3.9 km\2\ each. However, during monitoring of 
recent Navy actions at NBKB (test pile program and EHW-1 pile 
replacement) several sightings indicated that their presence may be 
more frequent in deeper waters of Hood Canal than had been believed on 
the basis of existing survey data and anecdotal evidence. Subsequently, 
the Navy conducted dedicated vessel-based line transect surveys on days 
when no pile driving occurred (due to security, weather, etc.), 
described previously in this document, with regular observations of 
harbor porpoise groups. Sightings in the deeper waters of Hood Canal 
ranged up to 11 individuals, with an average of approximately six 
animals sighted per survey day (Navy, in prep.).
    Sightings of harbor porpoises during these surveys 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; Caretta 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 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 259.01 km\2\. Thirty-five individual 
harbor porpoises were sighted within this area, resulting in a density 
of 0.135 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 density of 0.250 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\. Exposures were calculated using the 
formula described previously. Table 10 depicts the number of estimated 
behavioral harassments.
    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 10--Number of Potential Incidental Takes of Marine Mammals Within Various Acoustic Threshold Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Underwater                    Airborne
                                                                             ---------------------------------------------------------
                                                                                                     Vibratory                           Total proposed
                         Species                           Density/Abundance    Impact injury       disturbance           Impact        authorized takes
                                                                                threshold \1\      threshold (120      disturbance
                                                                                                        dB)           threshold \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion \2\.................................          \4\ 26.2                    0              5,070                  0              5,070
Steller sea lion........................................            \4\1.2                    0                195                  0                195
Harbor seal.............................................               1.31                   0             10,530                195             10,725
Killer whale............................................               0.038                  0                 90                N/A                 90
Dall's porpoise.........................................               0.014                  0                195                N/A                195
Harbor porpoise.........................................               0.250                  0              1,950                N/A              1,950
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................  ..................                  0             18,330                195             18,225
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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. NMFS does not believe that sea lions would be available for
  airborne acoustic harassment because they are known to haul-out only at locations well outside the zone in which airborne acoustic harassment could
  occur.

[[Page 79438]]

 
\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.

Negligible Impact and Small Numbers Analysis and Preliminary 
Determination

    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, 
NMFS considers 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 would occur without the use 
of a sound attenuation system (e.g., bubble curtain), and pile driving 
would either not start or be halted if marine mammals approach the 
shut-down zone (described previously in this document). The pile 
driving activities analyzed here are similar to other nearby 
construction activities within the Hood Canal, including two recent 
projects conducted by the Navy at the same location (test pile project 
and EHW-1 pile replacement project) 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 authorized take 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. 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. That is, it 
is likely that a relatively small subset of Hood Canal harbor seals, 
which is itself a small subset of the regional stock, would be harassed 
by project activities. While the available information and formula 
estimate that as many as 10,725 exposures of harbor seals to stimuli 
constituting Level B harassment could occur, that number represents 
some portion of the approximately 1,088 harbor seals resident in Hood 
Canal (approximately seven percent of the regional stock) that could 
potentially be exposed to sound produced by pile driving activities on 
multiple days during the project. 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 for Hood Canal 
harbor seals, and thus would not result in any adverse impact to the 
stock as a whole. Similarly, for killer whales, the estimated number of 
takes represents a single group of eleven whales that could potentially 
be exposed to sound on multiple days, if present. In fact, if a group 
of transient killer whales was present in the Hood Canal during the 
project (which is in itself unlikely, as such groups have appeared only 
twice since 2003), such a group would be able to simply leave the 
project area and forage elsewhere in Hood Canal or Puget Sound if the 
acoustic behavioral harassment caused by the project disturbed the 
group to a sufficient degree. However, it is difficult to quantify such 
a group's willingness to remain in the presence of behavioral 
harassment or, alternatively, to depart the project area. As such, NMFS 
proposes to authorize the take presented in Table 10, which represents 
the take of a single pod (approximately 11) that might be taken 
repeatedly over multiple days if they stayed in the area. The possible 
repeated exposure of a small group of individuals to levels associated 
with Level B harassment in this area is expected to have a negligible 
impact on the stock.
    For harbor porpoises, the situation relative to the regional stock 
(where estimated take is approximately eighteen percent) is less clear 
as little is known about their use of Hood Canal. Sightings information 
from opportunistic waterfront surveys as well as designed surveys of 
nearshore waters had previously indicated that harbor porpoises rarely 
occurred in NBKB waters. In addition, although no systematic survey 
work for harbor porpoises has occurred in Hood Canal, anecdotal 
evidence and expert opinion received through personal communication had 
confirmed that harbor porpoises were expected to occur infrequently and 
in low numbers in the project area. Recent Navy surveys, described 
previously in this document, have indicated that harbor porpoises are 
present in greater numbers than had been believed. It is unclear from 
the limited information available what relationship this occurrence, 
recorded only during September-October, 2011, may hold to the regional 
stock or whether similar usage of Hood Canal may be expected to recur 
throughout the project timeframe. Nevertheless, the estimated take of 
harbor porpoises is likely an overestimate (as it is based on 
information that may not hold true throughout the project timeframe) 
and should be considered to present a negligible impact on the stock. 
Harbor porpoise sightings to date have occurred only at significant 
distance from the project area (both inside and outside of the 
predicted 120-dB zone).
    NMFS has preliminarily determined that the impact of the previously 
described wharf construction 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

[[Page 79439]]

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, given 
sufficient ``notice'' through mitigation measures including soft start, 
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 shut-downs 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 number of marine mammals potentially incidentally 
harassed would depend on the distribution and abundance of marine 
mammals in the vicinity of the survey activity, the number of potential 
harassment takings is estimated to be small relative to regional stock 
or population number, and has 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.
    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, NMFS preliminarily finds that the proposed wharf construction 
project would result in the incidental take of small numbers of marine 
mammal, 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 or Stock 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 would 
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 is one ESA-listed marine mammal species with known occurrence 
in the project area: The Eastern DPS of the Steller sea lion, listed as 
threatened. Because of the potential presence of Steller sea lions, the 
Navy engaged in a formal consultation with the NMFS Northwest Regional 
Office under Section 7 of the ESA. The Biological Opinion associated 
with that consultation concluded that the proposed action is not likely 
to jeopardize the continued existence of the Steller sea lion. The 
Steller sea lion does not have critical habitat in the action area.

National Environmental Policy Act (NEPA)

    The Navy has prepared a preliminary final EIS. NMFS, which is a 
cooperating agency in the preparation of that document, will review it 
and the public comments received and subsequently either adopt it or 
prepare its own NEPA document before making a determination on the 
issuance of an IHA. The Navy EIS is available for public review at 
www.nbkeis.com.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes 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: December 14, 2011.
James H. Lecky
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2011-32549 Filed 12-20-11; 8:45 am]
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