[Federal Register Volume 76, Number 16 (Tuesday, January 25, 2011)]
[Notices]
[Pages 4300-4322]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-1528]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA075


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Test Pile Program

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 pile driving activities as part of a test 
pile program. 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, five species of marine mammals during 
the specified activity.

DATES: Comments and information must be received no later than February 
24, 2011.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910-3225. The mailbox address for 
providing e-mail comments is [email protected]. NMFS is not responsible 
for e-mail comments sent to addresses other than the one provided here. 
Comments sent via e-mail, 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.
    A 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. The Navy has prepared a 
draft Environmental Assessment (EA) titled ``Test Pile Program NBK 
Bangor Waterfront, Naval Base Kitsap Bangor, Silverdale, WA'', and has 
prepared a draft Essential Fish Habitat Assessment titled ``Test Pile 
Program NBK Bangor Waterfront Draft Essential Fish Habitat 
Assessment''. These associated documents, prepared in compliance with 
the National Environmental Policy Act (NEPA) and Magnuson-Stevens 
Fishery Conservation and Management Act, respectively, are also 
available at the same internet address. 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) 713-2289.

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

[[Page 4301]]

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 November 2, 2010 from the Navy for 
the taking of marine mammals incidental to pile driving in association 
with a test pile program in the Hood Canal at Naval Base Kitsap in 
Bangor, WA (NBKB). This test pile program is proposed to occur between 
July 16, 2011 and October 31, 2011. Six species of marine mammals may 
be present within 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. Steller sea lions are present 
only from fall to late spring (November-June), outside of the project's 
timeline (July 16-October 31). 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 decades 
and was therefore excluded from further analysis. Only the five species 
which may be present during the project's timeline may be exposed to 
sound pressure levels associated with vibratory and impulsive pile 
driving, and will be analyzed in detail in this document.
    The Navy proposes to install up to 29 test and reaction piles at 
NBKB to gather geotechnical and noise data to validate the design 
concept for the building of a new Explosive Handling Wharf (EHW-2), as 
well as for future projects at the NBKB waterfront. The test pile 
program will require a maximum of forty work days for completion. The 
forty work day duration of the program includes the time for the 
initial pile installations, time for performing loading tests, and time 
to remove all of the test piles. The pile lengths will range from 100-
197 ft (30-60 m), and range in diameter from 30-60 in (0.8-1.5 m). The 
test pile program will involve driving eighteen steel pipe piles, at 
pre-determined locations within the proposed footprint of EHW-2. Some 
of the initial eighteen piles will be removed and re-driven as part of 
lateral load and tension tests. A total of eleven piles will be 
installed to perform lateral load and tension load tests. All piles 
will be driven with a vibratory hammer for their initial embedment 
depths, and select piles will be impact driven for their final 10-15 ft 
(3-4.6 m) for proofing. ``Proofing'' involves driving a pile the last 
few feet into the substrate to determine the capacity of the pile. The 
capacity during proofing is established by measuring the resistance of 
the pile to a hammer that has a piston with a known weight and stroke 
(distance the hammer rises and falls) so that the energy on top of the 
pile can be calculated. The blow count in ``blows per inch'' is 
measured to verify resistance, and pile compression capacities are 
calculated using a known formula. Noise attenuation measures (i.e., 
bubble curtain) will be used during all impact hammer operations and on 
two of the vibratory-driven piles. Hydroacoustic monitoring will be 
performed to assess effectiveness of noise attenuation measures.
    For pile driving activities, the Navy used NMFS-promulgated 
thresholds for assessing pile driving 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 30-72 in (0.8-1.8 m) 
diameter steel 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 activities, and that 1,180 Level B harassments may 
occur during the test pile program from underwater sound. No incidents 
of harassment were predicted from airborne sounds associated with pile 
driving. Some assumptions (including marine mammal densities and other 
assumptions) used to estimate the exposures are conservative, and may 
overestimate the potential number of exposures and their severity.

Description of the Specified Activity

    NBKB is located on the Hood Canal approximately twenty miles (32 
km) west of Seattle, WA (see Figures 1-1 and 1-2 in the Navy's 
application). NBKB provides berthing and support services to Navy 
submarines and other fleet assets. The entirety of NBKB, including the 
land areas and adjacent water areas in the Hood Canal are restricted 
from general public access. The Navy proposes a test pile program to 
support the design of the future construction of EHW-2. The proposed 
actions with the potential to affect marine mammals within the 
waterways adjacent to NBKB that could result in harassment under the 
MMPA are vibratory and impulsive pile driving operations associated 
with the test pile program. The proposed pile driving activities will 
occur between July 16, 2011 and October 31, 2011. All in-water 
construction activities within the Hood Canal are only permitted during 
July 16-February 15 in order to protect spawning fish populations. The 
further restriction of in-water work window proposed by the Navy avoids 
the possibility of incidental harassment of Steller sea lions. The 
Eastern Distinct Population Segment (DPS) of Steller sea lions, present 
in the Hood Canal outside of the proposed project time period, is 
listed as threatened under the ESA.
    As part of the Navy's sea-based strategic deterrence mission, the 
Navy Strategic Systems Programs directs research, development, 
manufacturing, test, evaluation, and operational support of the TRIDENT 
Fleet Ballistic Missile program. Maintenance and development of 
necessary facilities for handling of explosive materials is part of 
these duties. The proposed action for this IHA request is to install 
and remove up to 29 test and reaction piles, conduct loading tests on 
select piles, and measure in-water sound propagation parameters (e.g., 
transmission loss) during pile installation and removal. Geotechnical 
and sound propagation data collected during pile installation and 
removal will be integrated into the design, construction, and 
environmental planning for the Navy's proposed EHW-2. Future 
construction projects at the NBKB waterfront may also benefit from the 
geotechnical data gathered for use in their environmental planning 
documentation. The Navy proposes to install the test piles in the 
location planned for the future EHW-2, which will be adjacent to the 
existing

[[Page 4302]]

Explosive Handling Wharf (EHW-1) at NBKB. The test pile program will 
require a maximum of forty work days for completion. Hydroacoustic 
monitoring will be undertaken to assess the effectiveness of noise 
attenuation measures. The presence of marine mammals will also be 
monitored during pile installation and removal.
    The test pile program has been designed to collect adequate 
geotechnical and sound propagation data. Under the proposed action, the 
Navy will install 29 test and reaction piles in the Hood Canal. The 
pile lengths will range from 100-197 ft (30-60 m), and range in 
diameter from 30-60 in (0.8-1.5 m). All piles will subsequently be 
removed at the completion of the test pile program. These test piles 
will be situated throughout the footprint of the future EHW-2, 
currently in the preliminary planning process. Figure 1-3 of the Navy's 
application shows in detail the locations of each of the test piles.
    The installation of the test piles will involve driving eighteen 
steel pipe piles into the substrate. Additionally, three lateral load 
and two tension load tests will be performed. The lateral load test 
involves measurements of lateral displacement versus load for the 
piles. The lateral load tests will require re-installing two 60-in (1.5 
m) diameter piles and one 48-in (1.2 m) diameter pile. The tension load 
test measures the vertical capacity of a pile. The tension load tests 
will require driving four reaction piles for each of the two tension 
load tests. The lateral load test in combination with the tension load 
test will result in the installation of an additional eleven piles. The 
Navy expects that some of the initial eighteen test piles will be 
removed and re-driven as part of lateral load and tension tests. Please 
see the Navy's application for a diagram of the lateral load and 
tension load tests, and for more specific information regarding each 
test pile (Figure 1-4 and Table 1-1 of the Navy's application, 
respectively).
    According to the Navy, previous soil boring studies, as well as 
experience at EHW-1, confirms that the substrate appears to be 
relatively consistent in nature across the site. Therefore, all of the 
piles will be driven by a vibratory hammer to their initial embedment 
depths. The eighteen test piles would likely require the use of an 
impact hammer to drive the piles the remaining 10-15 ft (3-4.6 m) into 
the substrate and for proofing. The impact driver will perform a few 
blows to warm up the hammer and a number of blows to verify capacity. A 
Pile Dynamic Analyzer will be utilized to confirm capacity. As a 
contingency, any piles that cannot be driven to their desired depth 
using the vibratory hammer may require the use of the impact hammer to 
finish installation. This contingency has been accounted for in the 
modeling analysis.
    The contractor is expected to mobilize two floating barges, one 
large barge up to 80 ft wide x 300 ft (24 x 91 m) long and one medium 
sized barge approximately 60 ft wide x 150 ft (18 x 46 m) long, for the 
test pile program. These barges will be moved into location with a 44 
ft (13 m) tug boat. The two barges will share the work load, with the 
smaller barge working the inboard test piles and the larger barge 
working the outboard test piles. The smaller barge will likely be on 
site for approximately two weeks of pile driving while the larger barge 
will be on site for the full duration of the program which is expected 
to be no longer than forty days. Only one pile driving rig will be 
operated at a time.
    Sound attenuation measures (e.g., bubble curtain) will be used 
during all impact hammer operations, and on two of the vibratory-driven 
piles, to test the practicability of using bubble curtains with a 
vibratory hammer. The Navy will monitor hydroacoustic levels, as well 
as the presence and behavior of marine mammals during pile installation 
and removal. All piles will be removed at or before the completion of 
the test pile program because they could pose a potential navigation 
risk if left in place. Removal is also necessary because the test piles 
will not be incorporated into the proposed EHW-2, as exact pile 
locations for the future structure have not yet been finalized.
    The test pile program will require a maximum of forty work days for 
completion. A work day is limited to the hours from two hours post-
sunrise to two hours prior to sunset. The forty work day duration of 
the program includes the time for the initial pile installations, time 
for performing the loading tests, and time to remove all of the test 
piles. A 108-day authorization window (16 July-31 October) was 
requested to take into account delays that could occur due to the 
permitting process, materials availability, and inclement weather that 
may preclude construction.
    The Navy's contractor estimates that pile installation could occur 
at a maximum rate of four piles per day. However, the Navy anticipates 
that an average of two piles will be installed and removed per day. For 
each pile installed, the driving time is expected to include no more 
than one hour for vibratory driving and fifteen minutes for the impact 
driving portion of the project, with a maximum 100 blows executed per 
day. The U.S. Fish and Wildlife Service (USFWS) requested that a 
maximum of 100 blows be executed per day in order to minimize potential 
injurious impacts to fish species which the marbled murrelet, listed as 
threatened under the ESA, prey upon. All piles will be extracted using 
a vibratory hammer. Extraction is anticipated to take approximately 
thirty minutes per pile. Overall, this results in an estimated maximum 
of two hours for driving and removal per pile, or approximately four 
hours per day. Therefore, while forty days of total in-water work time 
is proposed, only a fraction of the total work time will actually be 
spent on pile driving and removal.
    An average work day (two hours post-sunrise to two hours prior to 
sunset) ranges from six to twelve hours (for an average of 
approximately eight to nine hours), depending on the month. Although it 
is anticipated that only four hours would need to be spent on pile 
driving and removal per day, the Navy modeled potential impacts as if 
the entire day (i.e., eight to nine hours) could be spent pile driving 
to take into account deviations from the estimated times for pile 
installation and removal and to account for the additional use of the 
impact pile driver in case of failure of the vibratory hammer to reach 
the desired embedment depth. Based on the proposed action, the total 
pile driving time from vibratory or impact pile driving would be less 
than fifteen days (29 piles at an average of two per day, assuming an 
average of eight to nine hours of pile driving per day).

Description of Noise Sources

    Underwater sound levels are comprised of multiple sources, 
including physical noise, biological noise, and anthropogenic noise. 
Physical noise includes waves at the surface, earthquakes, ice, and 
atmospheric noise. Biological noise includes sounds produced by marine 
mammals, fish, and invertebrates. Anthropogenic noise consists of 
vessels (small and large), dredging, aircraft overflights, and 
construction noise. Known noise levels and frequency ranges associated 
with anthropogenic sources similar to those that would be used for this 
project are summarized in Table 1. Details of each of the sources are 
described in the following text.

[[Page 4303]]



                          Table 1--Representative Noise Levels of Anthropogenic Sources
----------------------------------------------------------------------------------------------------------------
                                            Frequency   Underwater noise level (dB
               Noise source                range (Hz)         re 1 [micro]Pa)                 Reference
----------------------------------------------------------------------------------------------------------------
Small vessels............................   250-1,000  151 dB root mean square       Richardson et al. 1995.
                                                        (rms) at 1 m.
Tug docking gravel barge.................   200-1,000  149 dB rms at 100 m (328 ft)  Blackwell and Greene 2002.
Vibratory driving of 72-in (1.8 m) steel     10-1,500  180 dB rms at 10 m (33 ft)..  CALTRANS 2007.
 pipe pile.
Impact driving of 36-in (0.9 m) steel        10-1,500  195 dB rms at 10 m..........  WSDOT 2007.
 Pipe pile.
Impact driving of 66-in (1.7 m) CISS\1\     100-1,500  195 dB rms at 10 m..........  Reviewed in Hastings and
 piles.                                                                               Popper 2005.
----------------------------------------------------------------------------------------------------------------
\1\ CISS = cast-in-steel-shell.

    In-water construction activities associated with the project would 
include impact pile driving and vibratory pile driving. The sounds 
produced by these activities fall into one of two sound types: pulsed 
and non-pulsed (defined in next paragraph). Impact pile driving 
produces pulsed sounds, while vibratory pile driving produces non-
pulsed (or continuous) sounds. 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, seismic 
pile driving pulses, 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 
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.

Ambient Noise

    By definition, ambient noise is background noise, without a single 
source or point (Richardson et al. 1995). Ambient noise varies with 
location, season, time of day, and frequency. Ambient noise is 
continuous, but with much variability on time scales ranging from less 
than one second to one year (Richardson et al. 1995). Ambient 
underwater noise at the project area is widely variable over time due 
to a number of natural and anthropogenic sources. Sources of naturally 
occurring underwater noise include wind, waves, precipitation, and 
biological noise (e.g., shrimp, fish, cetaceans). There is also human-
generated noise from ship or boat traffic and other mechanical means 
(Urick 1983). Other sources of underwater noise at industrial 
waterfronts could come from cranes, generators, and other types of 
mechanized equipment on wharves or the adjacent shoreline.
    In the vicinity of the project area, the average broadband ambient 
underwater noise levels were measured at 114 dB re 1[micro]Pa between 
100 Hz and 20 kHz (Slater 2009). Peak spectral noise from industrial 
activity was noted below the 300 Hz frequency, with maximum levels of 
110 dB re 1[micro]Pa noted in the 125 Hz band. In the 300 Hz to 5 kHz 
range, average levels ranged between 83-99 dB re 1[micro]Pa. Wind-
driven wave noise dominated the background noise environment at 
approximately 5 kHz and above, and ambient noise levels flattened above 
10 kHz.
    Airborne noise 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 noise ranging from 60-
80 dBA during daytime hours (Cavanaugh and Tocci 1998). The highest 
levels of airborne noise are produced along the waterfront and at the 
ordnance handling areas, where estimated noise levels range from 70-90 
dBA and may peak at 99 dBA for short durations. These higher noise 
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 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 noise thresholds have been established. Current NMFS practice 
regarding exposure of marine mammals to high level sounds 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 noise (e.g., vibratory pile driving), but 
below injurious thresholds. For airborne noise, pinniped disturbance 
from haul-outs has been documented at 100 dB (unweighted) for pinnipeds 
in general, and at 90 dB (unweighted) for harbor seals. NMFS uses these 
levels as guidelines to estimate when harassment may occur.

Distance to Sound Thresholds

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

TL = B * log10(R) + C * R, where

B = logarithmic (predominantly spreading) loss
C = linear (scattering and absorption) loss
R = range from source in meters


[[Page 4304]]


For all underwater calculations in this assessment, linear loss (C) was 
not used (i.e., C = 0) and transmission loss was calculated using only 
logarithmic spreading. Therefore, using practical spreading (B = 15), 
the revised formula for transmission loss is TL = 15 log10 
(R).
    Underwater Noise 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 sound pressure levels 
recorded from pile driving projects is available for consideration. In 
order to determine reasonable sound pressure levels 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. Studies which met the following parameters were 
considered: (1) Pile materials--steel pipe piles (30-72 in [0.8-1.8 m] 
diameter); (2) Hammer machinery--vibratory and impact; and (3) Physical 
environment--shallow depth (less than 100 ft [30 m]). Table 2 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 sound pressure levels which could be 
anticipated.

        Table 2--Underwater Sound Pressure Levels From Similar In-Situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
                                                         Installation                           Measured sound
       Project & location          Pile size & type         method            Water depth       pressure levels
----------------------------------------------------------------------------------------------------------------
Mukilteo Test Piles, WA\1\......  36-in (0.9 m)       Impact............  7.3 m (24 ft).....  195 dB re 1
                                   steel pipe.                                                 [micro]Pa (rms)
                                                                                               at 10 m (33 ft).
Richmond-San Rafael Bridge, CA    66-in (1.7 m)       Impact............  4 m (13.1 ft).....  195 dB re 1
 \2\.                              steel CISS pile.                                            [micro]Pa (rms)
                                                                                               at 10 m.
Unknown Location, CA \2\........  72-in (1.8 m)       Vibratory.........  Approximately 5 m   180 dB re 1
                                   steel pipe pile.                        (16.4 ft).          [micro]Pa (rms)
                                                                                               at 10 m.
----------------------------------------------------------------------------------------------------------------
\1\ WSDOT 2007.
\2\ CALTRANS 2007.

    Several noise reduction measures can be employed during pile 
driving to reduce the high source pressures associated with impact pile 
driving. Among these is the use of bubble curtains, cofferdams, pile 
caps, or the use of vibratory installation. The efficacy of bubble 
curtains is dependent upon a variety of site-specific factors, 
including environmental conditions such as water current, sediment 
type, and bathymetry; the type and size of the pile; and the type and 
energy of the hammer. For the test pile program, the Navy intends to 
employ noise reduction techniques during impact pile driving, including 
the use of the Gunderboom Sound Attenuation System (SAS) or traditional 
bubble curtain sound attenuation system. Additionally, vibratory pile 
driving will be the primary installation method, which has lower source 
levels than impact pile driving. The calculations of the distances to 
the marine mammal noise thresholds described previously were calculated 
for impact installation with and without consideration for mitigation 
measures. Thorson and Reyff (2004) determined that a properly designed 
bubble curtain could provide a reduction of 5 to 20 dB. Based on 
information contained therein, distances calculated with consideration 
for mitigation assumed 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. 
Calculations for the marine mammal noise thresholds for vibratory 
installation were done based on in-situ recordings of vibratory 
installation and extraction data from CALTRANS (2007) which indicated a 
sound pressure level (SPL) of 180 db re 1[micro]Pa at 10 m (33 ft). 
This concurred with published literature from other studies which have 
in the past used a 15 dB reduction factor from source levels from 
impact driving recordings to calculate source levels for vibratory pile 
driving. Sound levels associated with vibratory pile removal are the 
same as those during vibratory installation (CALTRANS 2007) and have 
been taken into consideration in the modeling analysis. All calculated 
distances to and the total area encompassed by the marine mammal noise 
thresholds are provided in Tables 3 and 4, respectively. Calculated 
distance to thresholds using unmitigated impact driving is provided as 
reference; no unmitigated impact driving will occur. The USFWS has 
requested this as a measure to protect prey of the ESA-endangered 
marbled murrelet.

         Table 3--Calculated Distance(s) to Underwater Marine Mammal Noise Thresholds From Pile Driving
----------------------------------------------------------------------------------------------------------------
                                                               Distance in meters (ft) to threshold
                                                 ---------------------------------------------------------------
                   Description                                                                       Vibratory
                                                  Impact Level A  Impact Level A  Impact Level B   Level B (120
                                                   (190 dB \1\)    (180 dB \1\)    (160 dB \1\)       dB \1\)
----------------------------------------------------------------------------------------------------------------
Impact Driving, no mitigation...................         22 (72)       100 (328)   2,154 (7,067)             N/A
Impact Driving with bubble curtain (Mitigation =          5 (16)         22 (72)     464 (1,522)             N/A
 10 dB reduction in SPLs).......................
Vibratory pile driver...........................           2 (7)         10 (33)             N/A     \2\ 100,000
                                                                                                       (328,084)
----------------------------------------------------------------------------------------------------------------
All sound levels expressed in dB re 1 [micro]Pa rms.
Practical spreading loss (15 log, or 4.5 dB per doubling of distance) used for water depths 10-50 ft (3-15 m).
\1\ Sound pressure levels used for calculations were: 195 dB re 1 [micro]Pa @ 10 m (33 ft) for impact and 180 dB
  re 1 [micro]Pa @ 10 m for vibratory.
\2\ Range calculated is greater than what would be realistic. 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).


[[Page 4305]]

    Calculated distances to thresholds, and calculated areas 
encompassed by thresholds, assume a field free of obstruction. This is 
unrealistic, however, because the Hood Canal does not represent open 
water conditions (free field) and therefore, sounds would attenuate as 
they encountered land masses or bends in the canal. As a result, some 
of the distances and areas of impact calculated cannot actually be 
attained within the project area. The actual distances to the 
behavioral disturbance thresholds for both impact and vibratory pile 
driving (464 m and 100,000 m [1,522 and 328,084 ft], respectively) may 
be shorter than those calculated due to the irregular contour of the 
waterfront, the narrowness of the canal, and the maximum fetch 
(furthest distance sound waves travel without obstruction [i.e., line 
of sight]) at the project area. Table 4 presents the calculated area 
encompassed for each threshold, as well as the actual area that is 
predicted to be encompassed due to obstructions as described above. 
Please see figures 6-1 and 6-2 in the Navy's application for graphical 
depictions of these areas for cetaceans and pinnipeds.

    Table 4--Area Encompassed (Per Pile) by the Underwater Marine Mammal Noise Thresholds From Pile Driving,
                                              Calculated and Actual
----------------------------------------------------------------------------------------------------------------
                                                  Area in square kilometers (mi\2\) encompassed by the threshold
                                                 ---------------------------------------------------------------
                   Description                                                                       Vibratory
                                                  Impact Level A  Impact Level A  Impact Level B   Level B (120
                                                   (190 dB \1\)    (180 dB \1\)    (160 dB \1\)       dB \1\)
----------------------------------------------------------------------------------------------------------------
Impact Driving with bubble curtain, calculated             0.000   0.002 (0.001)   0.676 (0.261)             N/A
 (Mitigation = 10 dB reduction in SPLs).........
Impact Driving with bubble curtain, actual                 0.000   0.002 (0.001)   0.509 (0.197)             N/A
 (Mitigation = 10 dB reduction in SPLs).........
Vibratory pile driver, calculated...............           0.000           0.000             N/A          31,416
                                                                                                        (12,130)
Vibratory pile driver, actual...................           0.000           0.000             N/A       41.5 (16)
----------------------------------------------------------------------------------------------------------------
\1\ Sound pressure levels used for calculations were: 195 dB re 1 [micro]Pa @ 10 m (33 ft) for impact and 180 dB
  re 1 [micro]Pa @ 10 m for vibratory.

    Airborne Sound Propagation Formula--Pile driving can generate 
airborne noise 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 sound pressure levels that could result in Level B 
behavioral harassment. The appropriate airborne noise 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 r
TL = Transmission loss
r = Distance from source to receiver

    *Spherical spreading results in a 6 dB decrease in sound pressure 
level per doubling of distance.
    Airborne Sound from Pile Driving--As was discussed for underwater 
noise 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 sound pressure levels 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 5 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 sound pressure levels which could be 
anticipated.

         Table 5--Airborne Sound Pressure Levels From Similar In-situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
                                                         Installation                           Measured sound
       Project & location          Pile size & type         method            Water depth       pressure levels
----------------------------------------------------------------------------------------------------------------
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 525 ft (160
                                                                                               m).
Keystone Ferry Terminal, WA \2\.  30-in (0.8 m)       Vibratory.........  Approximately 9 m   98 dB re 20
                                   steel pipe pile.                        (30 ft).            [micro]Pa (rms)
                                                                                               at 36 ft (11 m).
----------------------------------------------------------------------------------------------------------------
\1\ Blackwell et al. 2004.
\2\ WSDOT 2010.

    Based on in-situ recordings from similar construction activities, 
the maximum airborne noise levels that would result from impact and 
vibratory pile driving are estimated to be 97 dB re 20 [micro]Pa (rms) 
at 525 ft (160 m) and 98 dB re 20 [micro]Pa (rms) at 36 ft (11 m), 
respectively (Blackwell et al. 2004; WSDOT 2010). The distances to the 
airborne thresholds were calculated with the airborne transmission loss 
formula presented previously. All calculated distances to and the total 
area encompassed by the airborne marine mammal noise thresholds are 
provided in Tables 6 and 7, respectively.

[[Page 4306]]



          Table 6--Calculated Distances to the Marine Mammal Noise Thresholds In-Air From Pile Driving
----------------------------------------------------------------------------------------------------------------
                                                                         Airborne behavioral disturbance
                                                               -------------------------------------------------
               Species                        Threshold          Distance to threshold    Distance to threshold
                                                                  impact pile driving     vibratory pile driving
----------------------------------------------------------------------------------------------------------------
Pinnipeds (except harbor seal).......  100 dB re 20 [micro]Pa   113 m (371 ft).........  9 m (30 ft).
                                        rms (unweighted).
Harbor seal..........................  90 dB re 20 [micro]Pa    358 m (1,175 ft).......  28 m (92 ft).
                                        rms (unweighted).
----------------------------------------------------------------------------------------------------------------


 Table 7--Calculated Area Encompassed (Per Pile) by the Marine Mammal Noise Thresholds In-Air From Pile Driving
----------------------------------------------------------------------------------------------------------------
                                                                         Airborne behavioral disturbance
                                                               -------------------------------------------------
               Species                        Threshold         Area encompassed by the  Area encompassed by the
                                                                  threshold for impact   threshold for vibratory
                                                                      pile driving             pile driving
----------------------------------------------------------------------------------------------------------------
Pinnipeds (except harbor seal).......  100 dB re 20 [micro]Pa   0.040 km\2\ (.015        0.000 km\2\.
                                        rms (unweighted).        mi\2\).
Harbor seal..........................  90 dB re 20 [micro]Pa    0.403 km\2\ (0.156       0.002 km\2\ (.001
                                        rms (unweighted).        mi\2\).                  mi\2\).
----------------------------------------------------------------------------------------------------------------

    The distance to the sea lion airborne threshold would be 113 m (371 
ft) for impact pile driving, and 9 m (30 ft) for vibratory pile 
driving. The distance to the harbor seal airborne threshold would be 
358 m (1,175 ft) for impact pile driving, and 28 m (92 ft) for 
vibratory pile driving. These distances are all less than the distances 
calculated for underwater sound thresholds. Since protective measures 
are in place out to the distances calculated for the underwater 
thresholds, the distances for the airborne thresholds will be covered 
fully by mitigation and monitoring measures in place for underwater 
sound thresholds. All construction noise associated with the project 
would not extend beyond the buffer zone for underwater sound that would 
be established to protect seals and sea lions. No haul-outs or 
rookeries are located within these radii. Please see figures 6-3 and 6-
4 of the Navy's application for graphical depictions of the distances 
and total area encompassed by each airborne sound threshold for 
pinnipeds that are 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 decades, 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. As noted previously, and in Table 
8, Steller sea lions are not present in the project area during the 
proposed project timeframe (July 16-October 31). Steller sea lions will 
not be discussed in detail. 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 8 lists the marine mammal species that occur in the 
vicinity of NBKB and their estimated densities within the project area 
during the proposed timeframe.

                    Table 8--Marine Mammals Present in the Hood Canal in the Vicinity of NBKB
----------------------------------------------------------------------------------------------------------------
                                                                                                     Density in
                                                                Relative                            warm season
             Species                Stock  abundance \1\   occurrence in Hood       Season of           \3\
                                                                  Canal            occurrence      (individuals/
                                                                                                       km\2\)
----------------------------------------------------------------------------------------------------------------
Steller sea lion; Eastern U.S.                 \2\ 50,464  Rare to occasional  Fall to late                 N/A
 DPS.                                                       use.                spring (Nov-mid
                                                                                April).
California sea lion; U.S. Stock.                  238,000  Common............  Fall to late           \4\ 0.410
                                                                                spring (Aug-May).
Harbor seal; WA inland waters          14,612 (CV = 0.15)  Common............  Year-round;             \5\ 1.31
 stock.                                                                         resident species
                                                                                in Hood Canal.
Killer whale; West Coast                              314  Rare to occasional  Year-round........     \6\ 0.038
 transient stock.                                           use.
Dall's porpoise; CA/OR/WA stock.       48,376 (CV = 0.24)  Rare to occasional  Year-round........     \7\ 0.043
                                                            use.
Harbor porpoise; WA inland             10,682 (CV = 0.38)  Rare to occasional  Year-round........     \7\ 0.011
 waters stock.                                              use.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: http://www.nmfs.noaa.gov/pr/sars/species.htm.
\2\ Average of a given range.
\3\ Warm season refers to the period from May-Oct.
\4\ DoN 2010a.
\5\ Jeffries et al. 2003; Huber et al. 2001.
\6\ London 2006.
\7\ Agness and Tannenbaum 2009a.


[[Page 4307]]

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.
    Population Abundance--The U.S. stock of California sea lions may 
occur in the marine waters nearby NBKB. The stock 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). 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, 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).
    Peak abundance in the Puget Sound is September to May. Although 
there are no regular California sea lion haul-outs within the Hood 
Canal (Jeffries et al. 2000), they often haul out at several opportune 
areas. They are known to utilize man-made structures such as piers, 
jetties, offshore buoys, and oil platforms (Riedman 1990). California 
sea lions in the Puget Sound sometimes haul out on log booms and Navy 
submarines, and are often seen rafted off river mouths (Jeffries et al. 
2000; DoN 2001). As many as forty California sea lions have been 
observed hauled out at NBKB on manmade structures (e.g., submarines, 
floating security fence, barges) (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 noise 
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).

[[Page 4308]]

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).
    Population Abundance--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).
    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 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 Tannenbaum 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 (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 five-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

[[Page 4309]]

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.
    Population Abundance--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 
314 individuals for the West Coast transient stock (Allen and Angliss 
2010). However, the number in Washington waters at any one time is 
probably fewer than twenty individuals (Wiles 2004).
    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 produces 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 technique 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.
    Population Abundance--The NMFS population estimate, recently 
updated in 2008 for the CA/OR/WA stock, is 48,376 (CV = 0.24) which is 
based on vessel line transect surveys by Barlow and Forney (2007) and 
Forney (2007) (Carretta et al. 2008). The minimum population is 
considered to be 39,709. 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.
    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

[[Page 4310]]

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[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). 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.
    Population Abundance--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.
    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[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 may occasionally occur in Hood 
Canal (Jeffries 2006, pers. comm.). Harbor porpoise observations in 
northern Hood Canal have increased in recent years (Calambokidis 2010, 
pers. comm.). A harbor porpoise was seen in deeper water at NBKB during 
2010 field observations (SAIC 2010, staff obs.).
    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-

[[Page 4311]]

evoked potential method suggests that the harbor porpoise actually has 
two frequency ranges of best sensitivity. More recent psycho-acoustic 
studies 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 
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 will 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, two pinnipeds 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 Noise Effects

    Potential Effects of Pile Driving Noise--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) will 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 will 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 
noise 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

[[Page 4312]]

avoidance of the area where received levels of pile driving sound are 
high enough that hearing impairment could potentially occur. In those 
cases, the avoidance responses of the animals themselves will 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 noise 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 noise 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 noise levels

[[Page 4313]]

for a prolonged period of time. Based on the best scientific 
information available, these SPLs are far below the thresholds that 
could cause TTS or the onset of PTS.

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 
noise, 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 noise 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 noise, 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 noise 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 will 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 noise 
depends on both external factors (characteristics of noise 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, noise 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 noise 
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 noises are more likely to affect detection of communication calls 
and other potentially important natural sounds such as surf and prey 
noise. It may also affect communication signals when they occur near 
the noise 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 noise sources, such as those from vessel 
traffic, pile driving, and dredging activities, contribute to the 
elevated ambient noise levels, thus intensifying masking. However, the 
sum of noise from the proposed activities is confined in an area of 
inland waters (Hood Canal) that

[[Page 4314]]

is bounded by landmass; therefore, the noise generated is not expected 
to contribute to increased ocean ambient noise.
    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 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 Noise 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 noise would have less impact on 
cetaceans than pinnipeds because noise from atmospheric sources does 
not transmit well underwater (Richardson et al. 1995); thus, airborne 
noise 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 noise. 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 will 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 will be temporarily elevated noise 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 test pile program.

Pile Driving Effects on Potential Prey (Fish)

    Construction activities will 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 noise 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 test pile 
program. However, adverse impacts may occur to a few species of 
rockfish (bocaccio (Sebastes paucispinis) and 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 test pile program is 
relatively small compared to the available habitat in the Hood Canal. 
Potentially a maximum of 1.82 m\2\ (19.6 ft\2\; based on a 60 in [1.5 
m] diameter pile) of marine mammal foraging habitat may have decreased 
foraging value as each pile is driven. 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 noise associated with individual 
pile driving and removal, the short duration of the entire test pile 
program (forty work days), 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 essential 
fish habitat, or populations of fish species. Therefore, pile driving 
and removal is not likely to have a permanent, adverse effect on marine 
mammal foraging habitat at the project area. For more information, see 
the Navy's Draft Essential Fish Habitat Assessment (see ADDRESSES).

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

[[Page 4315]]

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 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 test pile program. In addition to the measures described later, the 
Navy will 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 noise standards of the U.S. 
Environmental Protection Agency and ensure that all construction 
equipment has noise control devices no less effective than those 
provided on the original equipment.
    (c) For in-water heavy machinery work other than pile driving (if 
it exists; e.g., standard barges, tug boats, barge-mounted excavators, 
or clamshell equipment used to place or remove material), if a marine 
mammal comes within 50 m (164 ft), operations shall cease and vessels 
shall reduce speed to the minimum level required to maintain steerage 
and safe working conditions.

Shutdown and Buffer Zone

    The following measures will apply to the Navy's mitigation through 
shutdown and buffer zones:
    (a) The Navy will implement a minimum shutdown zone of 50 m (164 
ft) radius 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, piledriving sounds are expected to attenuate below 180 dB at 
distances of 22 m or less (Table 3), but the 50-m shutdown is intended 
to further avoid the risk of direct interaction between marine mammals 
and the equipment.
    (b) The buffer zone shall include all areas where the underwater 
SPLs are anticipated to equal or exceed the 160-dB harassment 
isopleths. The radius of this zone will be 464 m (1,522 ft) at the 
start of pile driving work, but may be adjusted according to empirical, 
site-specific data after the project begins. The size of the 120-dB 
buffer zone for vibratory pile driving makes monitoring impracticable 
(see ``Sound Thresholds''; Table 3).
    (c) The shutdown and buffer zones will be monitored throughout the 
time required to drive 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 approaches or enters the shutdown zone, at which point all 
pile driving activities would be halted.
    (d) All buffer and shutdown zones will initially be based on the 
distances from the source that are predicted for each threshold level. 
However, in-situ acoustic monitoring will be utilized to determine the 
actual distances to these threshold zones, and the size of the shutdown 
and buffer zones will be adjusted accordingly based on received sound 
pressure levels.

Visual Monitoring

    Impact Installation--Monitoring will be conducted for a minimum 50 
m (164 ft) shutdown zone and a 464 m (1,522 ft) buffer zone (Level B 
harassment) surrounding each pile for the presence of marine mammals 
before, during, and after pile driving activities. Monitoring will take 
place from thirty minutes prior to initiation through thirty minutes 
post-completion of pile driving activities.
    Vibratory Installation--Monitoring will be conducted for a 50 m 
(164 ft) shutdown zone. The 120-dB disturbance criterion predicts an 
affected area of 41.5 km\2\ (16 mi\2\). Due to the impracticality of 
effectively monitoring such a large area, the Navy intends to monitor a 
buffer zone equivalent to the size of the Level B disturbance zone for 
impact pile driving (464 m) surrounding each pile for the presence of 
marine mammals before, during, and after pile driving activities. 
Sightings occurring outside this area will still be recorded and noted 
as a take, but detailed observations outside this zone will 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 will take place from thirty minutes prior to initiation 
through thirty minutes post-completion of pile driving activities.
    The following additional measures will apply to visual monitoring:
    (a) Monitoring will be conducted by qualified observers. A trained 
observer will 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 shutdown and 
safety zones will be monitored for thirty minutes to ensure that they 
are clear of marine mammals. Pile driving will only commence once 
observers have declared the shutdown zone clear of marine mammals; 
animals will be allowed to remain in the buffer zone (i.e., must leave 
of their own volition) and their behavior will be monitored and 
documented.
    (c) If a marine mammal approaches or enters the shutdown zone 
during the course of pile driving operations, pile driving will be 
halted and delayed until either the animal has voluntarily left and 
been visually confirmed beyond the shutdown zone or thirty minutes have 
passed without re-detection of the animal.

Sound Attenuation Devices

    Sound attenuation devices will 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 each pile. The Navy 
plans to use a Gunderboom Sound Attenuation System (SAS) as mitigation 
for in-water sound during construction activities. The Gunderboom SAS 
is a multipurpose enclosure that absorbs sound, attenuates pressure 
waves, excludes marine life from work areas, and controls the migration 
of debris, sediments and process fluids. The Gunderboom SAS is 
comprised of a water-permeable double layer of polypropylene/polyester 
fabric. Compressed air is released at the bottom of the fabric and 
moves up to the top of the fabric, inflating the fabric and creating a 
wall. A traditional bubble curtain will be used as a backup mitigation 
if the Navy cannot obtain the Gunderboom SAS or if it does not achieve 
the proposed noise attenuation. The Navy will also test the feasibility 
and effectiveness of using sound attenuation devices with vibratory

[[Page 4316]]

hammers. The Navy will employ the Gunderboom SAS or bubble curtain on 
two of the vibratory-driven piles to test the practicability of this 
concept.

Acoustic Measurements

    Acoustic measurements will be used to empirically verify the 
proposed shutdown 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. Further, the Navy has narrowed its 
work window to avoid times of year when ESA-listed Steller sea lions 
may be present at the project area. Therefore, all pile driving would 
only occur between July 16-October 31 of the approved in-water work 
window from July 16 through February 15 to minimize the number of fish 
exposed to underwater noise and other disturbance, and to avoid times 
when Steller sea lions are expected to be present.

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 test pile program will utilize soft-start techniques 
(ramp-up and dry fire) recommended by NMFS for impact and vibratory 
pile driving. The soft-start requires contractors to initiate noise 
from vibratory hammers for fifteen seconds at reduced energy followed 
by a one minute waiting period. This procedure will be repeated two 
additional times. For impact driving, contractors will be required to 
provide an initial set of three strikes from the impact hammer at forty 
percent energy, followed by a one minute waiting period, then two 
subsequent three strike sets.

Daylight Construction

    Pile driving will only be conducted between two hours post-sunrise 
through two hours prior to sunset (civil twilight).

Mitigation Effectiveness

    It should be recognized that although marine mammals will 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 will be 
experienced biologists with training in marine mammal detection and 
behavior. Due to their specialized training the Navy expects that 
visual mitigation will 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 kt (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 test pile program 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 test pile program at NBKB.
    Observers will be positioned in locations which provide the best 
vantage point(s) for monitoring. This will likely be an elevated 
position, providing a better range of viewing angles. Also, the 
shutdown and buffer zones have relatively small radii to monitor, which 
should improve detectability.
    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 will result 
in increased knowledge of the species and of the level of taking or 
impacts on populations of marine mammals that are expected to be 
present in the proposed action area.

Acoustic Measurements

    The Navy will conduct acoustic monitoring for impact driving of 
steel piles in order to determine the actual distances to the 190-, 
180-, and 160-dB (re 1 [mu]Pa rms) isopleths and to determine the 
relative effectiveness of the bubble curtain system at attenuating 
noise underwater. The Navy will also conduct acoustic monitoring for 
vibratory pile driving in order to determine the actual distance to the 
120-dB isopleth for behavioral harassment relative to background 
levels. The monitoring plan addresses both underwater and airborne 
sounds from the test pile program. At a minimum, the methodology will 
include:
    (1) A stationary hydrophone placed at mid-water depth and 10 m (33 
ft) from the source pile to measure the effectiveness of the bubble 
curtain system; a weighted tape measure will be used to determine the 
depth of the water. The hydrophone will be attached to a nylon cord or 
steel chain if current is swift enough, to maintain a constant distance 
from the pile. The nylon cord or chain will be attached to a float or

[[Page 4317]]

tied to a static line at the surface 10 m from the piles.
    (2) All hydrophones will be calibrated at the start of the action 
and will be checked at the beginning of each day of monitoring 
activity.
    (3) For each monitored location, a two-hydrophone setup will be 
used, with the first hydrophone at mid-depth and the second hydrophone 
at approximately 1 m (3.3 ft) from the bottom in order to evaluate site 
specific attenuation and propagation characteristics that may be 
present throughout the water column.
    (4) In addition to determining the area encompassed by the 190-, 
180-, 160-, and 120-db rms isopleths for marine mammals, hydrophones 
would also be placed at other distances as appropriate to accurately 
capture spreading loss occurring at the test pile project area.
    (5) Ambient conditions, both airborne and underwater, would be 
measured at the project site in the absence of construction activities 
to determine background sound levels. Ambient levels are intended to be 
recorded over the frequency range from 10 Hz to 20 kHz. Ambient 
conditions will be recorded for one minute every hour of the work day, 
for one week of each month of the test pile program.
    (6) Sound levels associated with soft-start techniques will also be 
measured.
    (7) Underwater sound pressure levels would be continuously 
monitored during the entire duration of each pile being driven. Sound 
pressure levels will be monitored in real time. Sound levels will be 
measured in Pascals, which are easily converted to decibel units.
    (8) Airborne levels would be recorded as unweighted, as well as in 
dBA, and the distance to marine mammal thresholds would be measured.
    (9) The effectiveness of using a bubble curtain system with a 
vibratory hammer will be tested during the driving of two vibratory 
piles. The on/off regime described in Table 9 will be utilized during 
the pile installation:

 Table 9--Schedule for Testing Effectiveness of Sound Attenuation Device
------------------------------------------------------------------------
                                              Sound  attenuation  device
           Pile driving timeframe                     condition
------------------------------------------------------------------------
Initial 30 s...............................  Off
Next minute (minimum)......................  On
Middle of pile driving segment 30 s........  Off
Next minute (minimum)......................  On
Final 30 s.................................  Off
------------------------------------------------------------------------

     (10) Environmental data would be collected, including, but not 
limited to: wind speed and direction, air temperature, humidity, 
surface water temperature, water depth, wave height, weather conditions 
and other factors that could contribute to influencing the airborne and 
underwater sound levels (e.g., aircraft, boats).
    (11) The chief inspector would supply the acoustics specialist with 
the substrate composition, hammer model and size, hammer energy 
settings and any changes to those settings during the piles being 
monitored, depth of the pile being driven, and blows per foot for the 
piles monitored.
    (12) Post-analysis of the sound level signals will include 
determination of absolute peak overpressure and under pressure levels 
recorded for each pile, rms value for each absolute peak pile strike, 
rise time, average duration of each pile strike, number of strikes per 
pile, SEL of the absolute peak pile strike, mean SEL, and cumulative 
SEL (accumulated SEL = single strike SEL + 10*log (number of hammer 
strikes) and a frequency spectrum both with and without mitigation, 
between 10-20,000 Hz for up to eight successive strikes with similar 
sound levels.

Visual Marine Mammal Observations

    The Navy will collect sighting data and behavioral responses to 
construction for marine mammal species observed in the region of 
activity during the period of activity. All observers will be trained 
in marine mammal identification and behaviors. NMFS requires that the 
observers have no other construction related tasks while conducting 
monitoring.
    Methods of Monitoring--The Navy will monitor the shutdown zone and 
safety (buffer) zone before, during, and after pile driving. Based on 
NMFS requirements, the Marine Mammal Monitoring Plan would include the 
following procedures for impact pile driving:
    (1) MMOs would be located at the best vantage point(s) in order to 
properly see the entire shutdown zone and safety zone. 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) To verify the required monitoring distances, the zones would be 
clearly marked with buoys or other suitable aquatic markers.
    (4) If the shut down or safety zones are obscured by fog or poor 
lighting conditions, pile driving would not be initiated until all 
zones are visible.
    (5) The shut down and safety zones around the pile will be 
monitored for the presence of marine mammals before, during, and after 
any pile driving activity.
    Pre-Activity Monitoring--The shutdown and buffer zones will be 
monitored for thirty 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 approximately thirty minutes, that the animal(s) 
has moved outside the shutdown zone.
    During Activity Monitoring--The shutdown and buffer zones will also 
be monitored throughout the time required to drive 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 
shutdown zone, at which point all pile driving activities will 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 thirty minutes.
    Post-Activity Monitoring--Monitoring of the shutdown and buffer 
zones would continue for thirty minutes following the completion of 
pile driving.

Data Collection

    NMFS requires that the PSOs use NMFS-approved sighting forms. In 
addition to the following requirements, the Navy will 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 will 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., 
wind, humidity, temperature);
    (4) Tide state and water currents;
    (5) Visibility;
    (6) Species, numbers, and, if possible, sex and age class of marine 
mammals;

[[Page 4318]]

    (7) Marine mammal behavior patterns observed, including bearing and 
direction of travel, and if possible, the correlation to sound pressure 
levels;
    (8) Distance from pile driving activities to marine mammals and 
distance from the marine mammals to the observation point;
    (9) Locations of all marine mammal observations; and
    (10) Other human activity in the area.

Reporting

    A draft report would be submitted to NMFS within 45 days of the 
completion 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. A 
final report would be prepared and submitted to NMFS within thirty days 
following receipt of comments on the draft report from NMFS. At a 
minimum, the report shall include:
    (1) Size and type of piles;
    (2) A detailed description of the SAS or bubble curtain, including 
design specifications;
    (3) The impact or vibratory hammer force used to drive and extract 
the piles;
    (4) A description of the monitoring equipment;
    (5) The distance between hydrophone(s) and pile;
    (6) The depth of the hydrophone(s);
    (7) The depth of water in which the pile was driven;
    (8) The depth into the substrate that the pile was driven;
    (9) The physical characteristics of the bottom substrate into which 
the piles were driven;
    (10) The ranges and means for peak, rms, and SELs for each pile;
    (11) 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;
    (12) The results of the airborne noise measurements including dBA 
and unweighted levels;
    (13) 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;
    (14) Results, including the detectability of marine mammals, 
species and numbers observed, sighting rates and distances, behavioral 
reactions within and outside of safety zones; and
    (15) A refined take estimate based on the number of marine mammals 
observed in the safety and buffer zones. This may be reported as one or 
both of the following: a rate of take (number of marine mammals per 
hour), or take based on density (number of individuals within the 
area).

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, there is no 
specific information demonstrating 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 or moving a small distance, the response may or may not rise 
to the level of ``taking'', or 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 noise on marine 
mammals, it is common practice to estimate how many mammals 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. While a pod of killer whales could potentially visit again 
during the project timeframe, and thus be ``taken'', it is more likely 
that they will 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. Therefore, behavioral disturbances that could 
result from anthropogenic noise associated with the proposed activities 
are expected to affect only a small number of marine mammals on an 
infrequent basis.
    The Navy is requesting authorization for the potential taking of 
small numbers of 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 test pile program described previously in this document. The 
takes requested are expected to have no more than a minor effect on 
individual animals and no effect on the populations of 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 noise.

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 impact pile driving and applied to each group-
specific noise impact threshold. The formula is founded on the 
following assumptions:
    (a) Each species population is at least as large as any previously 
documented highest population estimate.
    (b) All pilings to be installed would have a noise disturbance 
distance equal to the piling that causes the greatest noise disturbance 
(i.e., the piling furthest from shore).
    (c) Pile driving could potentially occur every day of the forty day 
in-water work window. However, it is estimated that an average of two 
piles will be installed and removed per day. Therefore, a best estimate 
of the number of days during which pile driving would occur is fifteen 
days, and this was used in all modeling calculations.
    (d) Some degree of mitigation (i.e., sound attenuation system, 
etc.) will be utilized, as discussed previously.
    (e) An individual can only be taken once per method of installation 
during a 24 hr period.
    The calculation for marine mammal takes is estimated by:

Take estimate = (n * ZOI) * 15 days of total activity

Where:

n = density estimate used for each species/season
ZOI = noise threshold zone of influence (ZOI) impact area; the area 
encompassed by all locations where the sound pressure levels equal 
or exceed the threshold being evaluated

[[Page 4319]]

n * ZOI produces an estimate of the abundance of animals that could 
be present in the area for exposure

    The ZOI impact area is the estimated range of impact to the noise 
criteria. The distances (actual) specified in Table 4 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. The ZOI 
impact area took into consideration the possible affected area of the 
Hood Canal from the pile driving site furthest from shore with 
attenuation due to land shadowing from bends in the canal. Because of 
the close proximity of some of the piles to the shore, the narrowness 
of the canal at the project area, and the maximum fetch, the ZOIs for 
each threshold are not necessarily spherical and may be truncated.
    As discussed previously in this document, the project entails forty 
days of total in-water work time. However, the Navy estimates that only 
fifteen days of pile driving will occur, with two piles driven per day. 
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 with no more 
than 100 blows executed per day. All piles will be extracted using a 
vibratory hammer. Extraction is anticipated to take approximately 
thirty minutes per pile. Overall, this results in a maximum of two 
hours of pile driving per pile, or approximately four hours per day. 
Impacts were modeled as if the action were to occur for a duration of 
fifteen days, and conservatively used an average of eight to nine hours 
per workday (two hours post-sunrise to two hours prior to sunset).
    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 significant note in these 
exposure estimates, additional mitigation methods (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. However, modeling did incorporate, for 
impact driving, a 10 dB reduction in SPL resulting from the use of 
sound attenuation devices. Results from acoustic impact exposure 
assessments should be regarded as conservative estimates that are 
strongly influenced by limited biological data. While the numbers 
generated from the pile driving exposure calculations provide 
conservative estimates of marine mammal exposures for consultation with 
NMFS, the short duration and limited geographic extent of the test pile 
project would likely further limit actual exposures.

California Sea Lion

    California sea lions are present in the Hood Canal almost year-
round with the exception of mid-June through August. The Navy conducted 
year round waterfront surveys for marine mammals at NBKB in 2008 and 
2009 (DoN 2010a). During these surveys, the daily maximum number of 
California sea lions hauled out for the months July-October (the 
timeframe of the test pile program), were 0, 0, 12, and 47 in 2008 and 
0, 1, 32, and 44 in 2009, respectively. The monthly average of the 
maximum number of California sea lions observed per day was seventeen 
individuals. Females are rarely observed north of the California-Oregon 
border (NMFS 2008c); therefore only adult and sub-adult males are 
expected in the Hood Canal. Breeding rookeries are in California; 
therefore pups are not expected to be present in the Hood Canal.
    California sea lions are not likely to be present at the project 
site during the entire period of work (i.e., are infrequent visitors 
during July-August). However, because the proportion of pile driving 
that could occur in a given month is dependent on several factors 
(e.g., availability of materials, weather) the Navy assumed that pile 
driving operations could occur at any time in the construction window. 
Therefore, exposures were calculated using the monthly average of the 
maximum number of California sea lions observed per day (seventeen 
individuals), divided by the potential acoustic impact area (41.5 km\2\ 
[16 mi\2\]) and the formula given previously. Table 10 depicts the 
number of acoustic harassments that are estimated from vibratory and 
impact pile driving both underwater and in-air for each season. The 
modeling indicated that zero California sea lions were likely to be 
exposed to sound in the 160-dB zone. However, the Navy feels that, 
based on the abundance of this species in the waters along NBKB and 
including their presence at nearby haul-outs, it is possible that an 
individual could pass through this zone in transit to or from a haul-
out. Therefore, the Navy is requesting a behavioral harassment take of 
California sea lion by impact pile driving each day of pile driving, 
for a total of fifteen takes over the course of the proposed action.

Harbor Seal

    Harbor seals are present in the Hood Canal year-round and would be 
expected at the project site. 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. Harbor seals are the most abundant marine mammal in the 
Hood Canal. Jeffries et al. (2003) did a stock assessment of harbor 
seals in the Hood Canal in 1999 and counted 711 harbor seals hauled 
out. This abundance was adjusted using a correction factor of 1.53 to 
account for seals in the water and not counted to provide a population 
estimate of 1,088 harbor seals in the Hood Canal. The Navy conducted 
boat surveys of the waterfront area in 2008 from July to September 
(Agness and Tannenbaum 2009a). Harbor seals were sighted during every 
survey and were found in all marine habitats including near and hauled-
out on man-made 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. From April 
through mid-July, female harbor seals haul out on the outer coast of 
Washington at pupping sites to give birth. Since there are no known 
pupping sites in the vicinity of the project, harbor seal pups are not 
expected to be present during pile driving. 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 ten miles (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.
    Research by Huber et al. (2001) indicates that approximately 35 
percent of harbor seals are in the water at any one time. 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.
    While Huber et al.'s (2001) data suggest that harbor seals 
typically spend 65 percent of their time hauled out, the Navy's 
waterfront surveys found that it is extremely rare for harbor seals to 
haul out in the vicinity of the test pile project area. Therefore, the 
only population of

[[Page 4320]]

harbor seals that could potentially be exposed to airborne sounds are 
those that are in-water but at the surface. Based on the diving cycle 
of tagged harbor seals near the San Juan Islands, the Navy estimates 
that seals are on the surface approximately 16.4 percent of their total 
in-water duration (Suryan and Harvey 1998). Therefore, by multiplying 
the percentage of time spent at the surface (16.4 percent) by the total 
in-water population of harbor seals at any one time (approximately 381 
individuals), the population of harbor seals with the potential to 
experience airborne impacts (approximately 63 individuals) can be 
obtained. Airborne exposures were calculated using a density derived 
from the maximum number of harbor seals available at the surface 
(approximately 63 individuals), divided by the area of the Hood Canal 
(291 km\2\) and the formula presented previously. Table 10 depicts the 
number of acoustic harassments that are estimated from vibratory and 
impact pile driving both underwater and in-air for each season.

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 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\ 
(0.015/mi\2\; eleven individuals divided by the area of the Hood Canal 
[291 km\2\]). Since this timeframe overlaps the period in which the 
test pile program will occur (July-October), this density was used for 
all exposure calculations. Exposures were calculated using the formula 
presented previously. Table 10 depicts the number of acoustic 
harassments that are estimated from vibratory and impact pile driving 
for each season. The modeling indicated that zero killer whales were 
likely to be exposed to sound in the 160-dB zone. However, while 
transient killer whales are rare in the Hood Canal, when these animals 
are present they occur in pods, so their density in the project area is 
unlikely to be uniform, as was modeled. If they are present during 
impact pile driving it is possible that one or more individuals within 
a pod could travel through the behavioral harassment zone. Therefore, 
the Navy is requesting nine behavioral takes of transient killer 
whales--based on the average size of pods seen previously in the Hood 
Canal--by impact pile driving over the course of the proposed action.

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 boat surveys of the waterfront area in 2008 from July to 
September (Agness and Tannenbaum 2009a). 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 seasonal density (warm season only [May-Oct]) was derived from the 
waterfront survey by the number of individuals seen divided by total 
number of kilometers of survey effort (six 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 
acoustic harassments that are estimated from vibratory and impact pile 
driving for each season. The modeling indicated that zero Dall's 
porpoises were likely to be exposed to sound in the 160-dB zone. Dall's 
porpoises are rare in the Hood Canal; only one animal, seen in deep 
waters offshore from the base, has been seen in the project area in the 
past few years. However, it is possible that additional animals exist 
or that this single individual could pass through the behavioral 
harassment zone for impulse sounds (160-dB) while transiting along the 
waterfront. Therefore, the Navy is requesting a single behavioral 
harassment take of a Dall's porpoise by impact pile driving over the 
course of the proposed action.

Harbor Porpoise

    Harbor porpoises may be present in the Hood Canal year-round; 
however, their presence is rare. During waterfront surveys of NBKB over 
the past two years (2008-present) only one harbor porpoise has been 
seen in 24 surveys.
    The Navy conducted boat surveys of the waterfront area from July to 
September over the past few years (2008-present) (Agness and Tannenbaum 
2009a). During one of the surveys a single harbor porpoise was sighted 
in the deeper waters offshore from the waterfront. In the absence of an 
abundance estimate for the entire Hood Canal, a seasonal density (warm 
season only) was derived from the waterfront survey by the number of 
individuals seen divided by total number of kilometers of survey effort 
(24 surveys with approximately 3.9 km\2\ [1.5 mi\2\] of effort each), 
assuming strip transect surveys. In the 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 acoustic harassments that 
are estimated from vibratory and impact pile driving for each season. 
The modeling indicated that zero harbor porpoises were likely to be 
exposed to sound in the 120-dB zone. However, while harbor porpoises 
are rare, one has been sighted in surveys over the last few years in 
the deep waters offshore from the base. It is possible this offshore 
region is encapsulated within the vibratory disturbance zone due to its 
size (41.5 km\2\ [16 mi\2\]). Therefore, based on the possibility that 
this animal could be present in the offshore waters during every day of 
construction, the Navy is requesting a single behavioral take of harbor 
porpoise by vibratory pile driving each day of pile driving, for a 
total of fifteen takes over the course of the proposed action.
    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 have a negligible short-term effect on 
individuals and would not result in population-level impacts.

[[Page 4321]]



                 Table 10--Number of Potential Warm Season (May-Oct) Exposures of Marine Mammals Within Various Acoustic Threshold Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Underwater                       Airborne
                                                                         ---------------------------------------------------------------- Total (percent
                                                                                              Impact         Vibratory       Impact &       of stock or
                         Species                              Density      Impact injury    disturbance     disturbance      vibratory      population
                                                                           threshold \1\  threshold (160  threshold (120    disturbance        \3\)
                                                                                                dB)             dB)        threshold \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion.....................................           0.410               0             *15             255               0      270 (0.01)
Harbor seal.............................................            1.31               0              15             810           0 \4\       825 (5.6)
Killer whale............................................           0.038               0              *9              30             N/A       39 (12.4)
Dall's porpoise.........................................           0.043               0              *1              30             N/A       31 (0.06)
Harbor porpoise.........................................           0.011               0               0             *15             N/A        15 (0.1)
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................               0              40            1140               0            1180  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------
* See species descriptions for discussion of these estimates.
\1\ Acoustic injury threshold for impact pile driving is 190 dB for pinnipeds and 180 dB for cetaceans.
\2\ Acoustic disturbance threshold is 100 dB for California sea lions; 90 dB for harbor seals. The airborne exposure calculations assume that 100% of
  the in-water densities were available at the surface to be exposed to airborne sound.
\3\ See Table 8 for stock or population numbers.
\4\ Airborne densities were based on the percentage (16.4 percent) of in-water density available at the surface to be exposed (Suryan and Harvey 1998).

    During the project timeframe, which occurs entirely in the May to 
October warm season, there is the potential for forty Level B 
disturbance takes (160-dB, impulse sound) of various species from 
impact pile driving operations, and an additional 1,140 Level B 
disturbance takes (120-dB, continuous sound) of various species from 
vibratory pile driving due to underwater sound. The following species 
and numbers of Level B disturbance takes could occur due to underwater 
sound as a result of impact pile driving operations: fifteen California 
sea lions, fifteen harbor seals, nine transient killer whales, and one 
Dall's porpoise. The following species and numbers of Level B 
disturbance takes could occur due to underwater sound as a result of 
vibratory pile driving operations: 255 California sea lions, 810 harbor 
seals, thirty transient killer whales, thirty Dall's porpoises, and 
fifteen harbor porpoises. Due to their lack of presence within the 
project area during the timeframe for the test pile program (July 16-
Oct 31), no Steller sea lions would be harassed. Lastly, no species of 
pinnipeds are expected to be exposed to airborne sound pressure levels 
that would cause harassment.

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 test pile program, as 
outlined previously, have the potential to disturb or displace small 
numbers of 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. Level A harassment is not anticipated given the methods 
of installation and measures designed to minimize the possibility of 
injury to marine mammals. Specifically, vibratory hammers will be the 
primary method of installation, which are not expected to cause injury 
to marine mammals due to the relatively low source levels (less than 
190 dB). Also, no impact pile driving will occur without the use of a 
noise attenuation system (e.g., bubble curtain), and pile driving will 
either not start or be halted if marine mammals approach the shutdown 
zone (described previously in this document). Furthermore, the pile 
driving activities analyzed are similar to other nearby construction 
activities within the Hood Canal, such as test piles driven in 2005 for 
the Hood Canal Bridge (SR-104) constructed by the Washington Department 
of Transportation, which have taken place with no reported injuries or 
mortality to marine mammals.
    NMFS has preliminarily determined that the impact of the previously 
described test pile program 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 haul-out areas near or adjacent to the project site means that 
potential takes by disturbance will have an insignificant short-term 
effect on individuals and would not result in population-level impacts. 
Similarly, for cetacean species the absence of any regular occurrence 
adjacent to the project site means that potential takes by disturbance 
will 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. This activity is 
expected to result in a negligible impact on the affected species or 
stocks. None of the species for which take authorization is requested 
are either ESA-listed or considered depleted under the MMPA.
    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 noise 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

[[Page 4322]]

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 will be avoided through the incorporation of 
the proposed mitigation measures.
    While the number of marine mammals potentially incidentally 
harassed will 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.
    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 test pile program 
will result in the incidental take of small numbers of marine mammal, 
by Level B harassment only, and that the total taking from the activity 
will 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 marine mammal species that is listed as endangered 
under the ESA with confirmed or possible occurrence in the study area: 
the Eastern DPS of the Steller sea lion. However, as described 
previously, the project will occur from July 16-October 31 only, a time 
at which Steller sea lions are not present in the project area. The 
Navy conducted an informal consultation with the NWRO under Section 7 
of the ESA; the NWRO concurred that there would be no presence of ESA-
listed marine mammals during the project and that formal consultation 
was not required.

National Environmental Policy Act (NEPA)

    In November 2010, the Navy prepared a draft EA, which has been 
posted on the NMFS Web site (see ADDRESSES) concurrently with the 
publication of this proposed IHA and public comments have been 
solicited. NMFS will review the draft EA 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.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
authorize the take of marine mammals incidental to the Navy's test pile 
program, provided the previously mentioned mitigation, monitoring, and 
reporting requirements are incorporated.

    Dated: January 18, 2011.
Helen M. Golde,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2011-1528 Filed 1-24-11; 8:45 am]
BILLING CODE 3510-22-P