[Federal Register Volume 78, Number 100 (Thursday, May 23, 2013)]
[Notices]
[Pages 30873-30894]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-12251]



[[Page 30873]]

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XC622


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Pier Replacement Project

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

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

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

DATES: Comments and information must be received no later than June 24, 
2013.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, Chief, Permits and Conservation Division, Office of Protected 
Resources, National Marine Fisheries Service, 1315 East-West Highway, 
Silver Spring, MD 20910. The mailbox address for providing email 
comments is [email protected]. NMFS is not responsible for email 
comments sent to addresses other than the one provided here. Comments 
sent via email, including all attachments, must not exceed a 10-
megabyte file size.
    Instructions: All comments received are a part of the public 
record. All Personal Identifying Information (e.g., name, address) 
voluntarily submitted by the commenter may be publicly accessible. Do 
not submit Confidential Business Information or otherwise sensitive or 
protected information.
    A copy of the application as well as a list of the references used 
in this document may be obtained by writing to the address specified 
above, telephoning the contact listed below (see FOR FURTHER 
INFORMATION CONTACT), or visiting the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Supplemental documents 
provided by the U.S. Navy may be found at the same web address. The 
Navy has prepared a Draft Environmental Assessment (Naval Base Point 
Loma Fuel Pier Replacement and Dredging (P-151/DESC1306) Environmental 
Assessment) in accordance with the National Environmental Policy Act 
(NEPA) and the regulations published by the Council on Environmental 
Quality. It is posted at the foregoing site. NMFS will independently 
evaluate the EA and determine whether or not to adopt it. We may 
prepare a separate NEPA analysis and incorporate relevant portions of 
the Navy's EA by reference. Information in the Navy's application, EA 
and this notice collectively provide the environmental information 
related to proposed issuance of the IHA for public review and comment. 
We will review all comments submitted in response to this notice as we 
complete the NEPA process, including a decision of whether to sign a 
Finding of No Significant Impact (FONSI), prior to a final decision on 
the IHA request. Documents cited in this notice may also be viewed, by 
appointment only, at the aforementioned physical address.

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

SUPPLEMENTARY INFORMATION:

Background

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

Summary of Request

    We received an application on September 24, 2012 from the Navy for 
the taking of marine mammals incidental to pile driving and removal in 
association with a pier replacement project in San Diego Bay at Naval 
Base Point Loma in San Diego, CA (NBPL). The Navy submitted a revised 
version of the application on November 15, 2012 which we deemed 
adequate and complete. The pier replacement project is proposed to 
occur over multiple years; however, this IHA would cover only the 
initial year of work, beginning September 1, 2013. Four species of 
marine mammals are expected to occur in the vicinity of the project 
during all or a portion of the project duration: California sea lion 
(Zalophus californianus californianus), harbor seal (Phoca vitulina 
richardii), bottlenose dolphin (Tursiops truncatus truncatus), and gray 
whale (Eschrichtius robustus). California sea lions are present year-
round and are common in the project area, while bottlenose dolphins may 
be present year-round but sightings are highly variable in Navy marine 
mammal surveys of northern San Diego Bay. Harbor seals have limited 
occurrence in the project area. Gray whales may be observed in San 
Diego Bay sporadically during migration periods.
    NBPL provides berthing and support services for Navy submarines and 
other fleet assets. The existing fuel pier serves as a fuel depot for 
loading and unloading tankers and Navy underway replenishment vessels 
that refuel ships at sea (``oilers''), as well as transferring fuel to 
local replenishment vessels and

[[Page 30874]]

other small craft operating in San Diego Bay, and is the only active 
Navy fueling facility in southern California. Portions of the pier are 
over one hundred years old, while the newer segment was constructed in 
1942. The pier as a whole is significantly past its design service life 
and does not meet current construction standards.
    Demolition and construction would occur in two phases to maintain 
the fueling capabilities of the existing fuel pier while the new pier 
is being constructed. The total duration of demolition/construction is 
estimated to be approximately four years (2013-17). During the first 
year of construction (the specified activity considered under this 
proposed IHA), approximately 120 piles (including 18-in concrete and 
36- to 48-in steel) would be installed and 109 piles would be removed 
(via multiple methods). All steel piles would be driven with a 
vibratory hammer for their initial embedment depths and finished with 
an impact hammer for proofing, as necessary. Proofing involves striking 
a driven pile with an impact hammer to verify that it provides the 
required load-bearing capacity, as indicated by the number of hammer 
blows per foot of pile advancement.
    For pile driving activities, the Navy used NMFS-promulgated 
thresholds for assessing project impacts, outlined later in this 
document. The Navy used a site-specific model for transmission loss and 
empirically-measured source levels from other 36-72 in diameter pile 
driving events to estimate potential marine mammal exposures. Predicted 
exposures are outlined later in this document. The calculations predict 
that no Level A harassments would occur associated with pile driving or 
construction activities, and that as many as 1,738 incidents of Level B 
harassment may occur during the first year of the pier replacement 
project from sound produced by pile driving and removal activity.

Description of the Specified Activity

    NBPL is located on the peninsula of Point Loma near the mouth and 
along the northern edge of San Diego Bay (see Figures 1-1 and 1-2 in 
the Navy's application). The proposed actions with the potential to 
cause harassment of marine mammals within the waterways adjacent to 
NBPL, under the MMPA, are vibratory and impact pile driving and removal 
of piles via vibratory driver or pneumatic chipper associated with the 
pier replacement project and associated projects. The entire project is 
scheduled to occur from 2013-17; the proposed activities that would be 
authorized by this IHA would occur for one year from September 1, 2013. 
Under the terms of a memorandum of understanding between the Navy and 
the U.S. Fish and Wildlife Service, all noise- and turbidity-producing 
in-water activities in designated least tern foraging habitat are to be 
avoided during the period when least terns are present and engaged in 
nesting and foraging. Therefore, all in-water construction activities 
will occur during a window from approximately September 15 through 
April 1.

Specific Geographic Region

    San Diego Bay is a narrow, crescent-shaped natural embayment 
oriented northwest-southeast with an approximate length of fifteen 
miles and a total area of roughly 11,000 acres. The width of the bay 
ranges from 0.2 to 3.6 miles, and depths range from 74 ft mean lower 
low water (MLLW) near the tip of Ballast Point to less than 4 ft at the 
southern end (see Figure 2-1 of the Navy's application). San Diego Bay 
is a heavily urbanized area with a mix of industrial, military, and 
recreational uses. The northern and central portions of the bay have 
been shaped by historic dredging to support large ship navigation. 
Dredging occurs as necessary to maintain constant depth within the 
navigation channel. Outside the navigation channel, the bay floor 
consists of platforms at depths that vary slightly. Sediments in 
northern San Diego Bay are relatively sandy as tidal currents tend to 
keep the finer silt and clay fractions in suspension, except in harbors 
and elsewhere in the lee of structures where water movement is 
diminished. Much of the shoreline consists of riprap and manmade 
structures.
    San Diego Bay is heavily used by commercial, recreational, and 
military vessels, with an average of 82,413 vessel movements (in or out 
of the bay) per year (not including recreational boating within the 
Bay) (see Table 2-2 of the Navy's application). The Navy has been 
measuring underwater noise in northern San Diego Bay and has thus far 
found that the median broadband sound pressure level for background 
sound in the Bay is 123.8 dB re 1 [mu]Pa. These preliminary data 
reflect the busy nature of the project area and show that background 
sound may be higher than the NMFS-specified Level B harassment 
threshold of 120 dB for continuous sound (see Figures 2-4 to 2-6 of the 
Navy's application). The Navy intends to continue gathering ambient 
sound data for the project area and this subject will be addressed in 
greater detail under future IHA requests. For more information about 
the specific geographic region, please see section 2.3 of the Navy's 
application.
    In order to provide context, we will first describe the entire 
project and then describe the specific portions scheduled for 
completion during the first work window. Associated projects (separate 
from primary construction/demolition) are described first. The project 
consists of the following key elements:

Temporary Relocation of the Marine Mammal Program

    The Navy Marine Mammal Program, administered by Space and Naval 
Warfare Systems Command (SPAWAR) Systems Center (SSC), would be moved 
approximately three kilometers to the Naval Mine and Anti-submarine 
Warfare Command (NMAWC). Although not subject to the MMPA, SSC's 
working animals are being relocated so that they will not be affected 
by the project. In addition to the distance of remove, NMAWC is 
acoustically shadowed from potential project noise (see Figure 1-4 of 
the Navy's application). Construction of the temporary holding facility 
would include impact driving fifty 18-in square concrete piles. After 
completion of the new fuel pier the Marine Mammal Program would move 
back to its original location adjacent to the fuel pier and the 
temporary facilities at NMAWC would be removed.

Temporary Relocation of Bait Barges

    The Everingham Brothers San Diego Bay Bait Barge facility will be 
temporarily relocated by the owners. Although not an element of the 
Navy's Fuel Pier Replacement Project, this action is mentioned here 
because the barges, currently anchored approximately 600 m south of the 
existing fuel pier, attract large numbers of California sea lions and 
their relocation would be expected to reduce the number of sea lions 
that would be exposed to noise levels constituting harassment under the 
MMPA. The barges would be moved to either of two locations along the 
southwest side of Harbor Island, approximately five kilometers from the 
project site (see Figure 1-5 in the Navy's application). The Bait Barge 
would be moved prior to the initiation of in-water construction and may 
be moved back to the current location when in-water construction is 
complete.

Dredging and Sediment Disposal

    Dredging and sediment disposal are needed to deepen the existing 
turning basin in order to safely accommodate current and future deep 
draft berthing capabilities. An estimated 80,000 yd\3\ of sediment 
would be dredged. Laboratory

[[Page 30875]]

testing of the sediments confirmed the lack of contamination and they 
were approved for ocean disposal by the U.S. Environmental Protection 
Agency and U.S. Army Corps of Engineers. However, the sediments also 
have sufficient content of sand for beneficial reuse in nearshore 
replenishment. Accordingly, the sediments would be transported by barge 
and deposited at an approved nearshore replenishment site (Imperial 
Beach). Noise measurements of dredging activities are rare in the 
literature, but dredging is considered to be a low-impact activity for 
marine mammals, producing non-pulsed sound and being substantially 
quieter in terms of acoustic energy output than sources such as seismic 
airguns and impact pile driving. Noise produced by dredging operations 
has been compared to that produced by a commercial vessel travelling at 
modest speed (Robinson et al., 2011). Further discussion of dredging 
sound production may be found in the literature (e.g., Richardson et 
al., 1995, Nedwell et al., 2008, Parvin et al., 2008, Ainslie et al., 
2009). Generally, the effects of dredging on marine mammals are not 
expected to rise to the level of a take. Therefore, this project 
component will not be discussed further.

Construction of the New Pier and Demolition and Removal of the Existing 
Pier

    Demolition and construction would occur on a segment-by-segment 
basis to allow for continuous fueling operations during the project. 
The south side of the existing pier would remain operational while the 
north side is undergoing demolition and the new pier is being 
constructed. When construction of the new pier is complete, the 
remainder of the old pier would be demolished. See Table 1-1 in the 
Navy's application for a complete construction phase summary. More 
detail is provided below only on those aspects of the project that 
involve in-water activity and that have the potential to result in 
incidental take of marine mammals. The majority of the work would be 
conducted over water and would include removal of the pier, pilings, 
plastic camels and fenders. All utility infrastructure would be 
removed, including water and sewer pipelines, lighting systems, and 
wiring. The fueling systems, including piping and pipe supports, would 
also be removed. These and other aspects of the project are considered 
in more detail in the Navy's Draft Environmental Assessment.
    Methods, Pile Removal--Typical pier demolition takes place bayward 
to landward and from the top down. Fender piles and exterior 
appurtenances (such as utilities and the fuel piping systems) would 
first be removed above and below the pier deck before the deck would be 
demolished using concrete saws and a barge-mounted excavator equipped 
with a hydraulic breaker. Next, structural and fender piles would be 
demolished. Table 1 summarizes the total number and nature of existing 
piles to be removed.

          Table 1--Existing Fuel Pier Total Piles and Caissons
                             [To be removed]
------------------------------------------------------------------------
                    Pile type or structure                      Quantity
------------------------------------------------------------------------
16-in concrete structural piles..............................        518
14- and 24-in concrete fender piles..........................        105
13-in plastic fender piles...................................         34
16-in steel pipe filled with concrete........................         24
12-in timber piles...........................................        739
66-in diameter concrete-filled steel caissons................         26
84-in diameter concrete-filled steel caissons................         25
                                                              ----------
  Total......................................................      1,471
------------------------------------------------------------------------

    There are multiple methods for pile removal, including dry pulling, 
cutting at the mudline, jetting, and vibratory removal. Typically piles 
would be cut off at the mudline; however, the full length of the piles 
would be pulled at the area where the new approach segment would be 
constructed. An attempt would first be made to dry pull the piles with 
a barge-mounted crane. A vibratory hammer or a pneumatic chipper may be 
used to loosen the piles. Jetting (the application of a focused stream 
of water under high pressure) would be another option to loosen piles 
that could not be removed through the previous procedures. The caisson 
elements would be removed with a clamshell, which is a dredging bucket 
consisting of two similar halves that open/close at the bottom and are 
hinged at the top. The clamshell would be used to grasp and lift large 
components. When a wooden pile cannot be completely pulled out, the 
pile may be cut at the mudline using the clamshell's hydraulic jaws 
and/or a diver-operated underwater chainsaw, except for piles that are 
within the footprint of the approach pier, which may require jetting to 
remove.
    Methods, Pile Installation--In general, pile installation work 
would be accomplished during the in-water work window from September 
through March, with installation of deck and utility components as well 
as acceptable demolition work (i.e., work that is not considered a 
significant source of underwater noise or turbidity) occurring from 
April through August. Pile driving would occur during normal working 
hours (7:00 a.m. to 4:00 p.m.). The impact pile driver would be used 
for all types of piles (steel, concrete and fiberglass). For steel 
piles, a vibratory hammer would be used to drive the pile to refusal 
and then the impact hammer would be used for proofing or until the pile 
meets structural requirements (expected to require 25-125 blows). The 
concrete piles would first be jetted, a process wherein pressurized air 
or water jets are applied at the tip of the pile to loosen the 
substrate and allow the pile to sink vertically, before being driven 
the last few feet with the impact hammer. The fiberglass piles do not 
need to be embedded very deeply into the subsurface so would be impact-
driven for the entire length. In all cases, impact driving would be 
minimized.
    The replacement pier structure, including the mooring dolphins, 
would consist of steel pipe piles, supporting concrete pile caps and 
cast-in-place concrete deck slabs. The upper 10 ft of the steel wall 
pipe piles would be filled with concrete as part of the connection 
between the piles and the pier deck. Approximately 554 total piles 
would be installed, including 228 36-in steel pipe piles, 77 48-in 
steel pipe piles, 84 16-in concrete-filled fiberglass piles, and 165 
24-in prestressed concrete piles. The sizes of the steel piles are 
dependent on water depth, subsurface soil conditions, and the mass of 
the deck structure. In most areas, a 36-in diameter steel pile is 
adequate to meet the criteria. In other areas, a 48-in diameter pile is 
necessary. Table 1-4 in the Navy's application summarizes the total 
piles that would be installed over the life of the project.
    Project Indicator Pile Program and Temporary Mooring Dolphin 
(March-April 2014); North Segment Demolition (March-July 2014)--The 
Indicator Pile Program (IPP) is designed to validate the length of pile 
required and the method of installation (vibratory and impact). 
Approximately twelve steel pipe piles (36- and 48-in diameter, exact 
mix to be determined later) would be driven in the new pier alignment 
to verify the driving conditions and establish the final driving 
lengths prior to fabrication of the final production piles that would 
be used to construct the new pier. In addition, the IPP will validate 
the acoustics modeling used by the Navy to estimate incidental take 
levels.
    A temporary mooring dolphin would be constructed to allow vessels 
to berth and load/unload fuel on the existing south segment while the 
north segment of the existing pier is under demolition.

[[Page 30876]]

Sixteen 36-in piles would be driven during construction. The north 
segment would be demolished by water access using barges to provide a 
working area for the crane and equipment. Some equipment used for 
demolition may include: hydraulic hammers mounted to back-hoes for 
breaking concrete, front-end loaders, fork-lifts, concrete saws, steel 
cutting torches, and excavators with hydraulic thumb shears.
    Approach Pier Construction, North Pier Construction and Mooring 
Dolphins (March 2014-September 2016)--The north pier would be 
constructed concurrently with the approach pier. Two mooring dolphins 
and connecting catwalks would also be constructed at this time.
    South Pier Construction (September 2016-November 2016)--The south 
berthing dolphin and mooring dolphin construction would begin after the 
approach pier, north pier, and mooring dolphins are operational.
    South Pier and Approach Pier Demolition (June 2016-November 2016)--
The old south pier and old approach pier demolition would begin after 
the new south pier is operational. The temporary mooring dolphin near 
the north pier would also be demolished at this time.
    The currently proposed action (i.e., the specified activity for the 
one-year period of this proposed IHA) includes pile driving associated 
with relocation of the Navy Marine Mammal Program (MMP), pile driving 
associated with the Indicator Pile Program and construction of the 
temporary mooring dolphin, and beginning of construction of the new 
pier structure. In addition, pile removal associated with demolition of 
the old structure will begin. These activities are detailed in Table 2. 
As described under Methods, the majority of pile removal will likely 
not require the use of vibratory extraction and/or pneumatic chipping, 
and these methods are included here as contingency in the event other 
methods of extraction are not successful.

                                       Table 2--Specified Activity Summary
                                                    [2013-14]
----------------------------------------------------------------------------------------------------------------
                Activity                         Timing (days)                 Pile type           Number piles
----------------------------------------------------------------------------------------------------------------
MMP relocation (at NMAWC)...............  Sep-Oct 2013 (16).........  18-in square concrete.....              50
Indicator Pile Program..................  Mar 2014 (17).............  36- and 48-in steel pipe..              12
Temporary mooring dolphin...............  Mar 2014 (5)..............  36-in steel pipe..........              16
Abutment pile driving...................  Mar-Apr 2014 (13).........  48-in steel pipe..........              24
Structural pile driving.................  Mar-Apr 2014 (15).........  36- and 48-in steel pipe..              26
                                         -----------------------------------------------------------------------
    Total installed.....................  ..........................  ..........................             128
                                         -----------------------------------------------------------------------
Pile removal \1\........................  Mar-Sep 2014..............  16- and 24-in square                    18
                                                                       concrete.
Pile removal \1\........................  Mar-Sep 2014..............  12-in timber..............              91
----------------------------------------------------------------------------------------------------------------
\1\ Pile removal schedule is notional and is dependent on contractor workload and timing of in-water work
  shutdown in spring 2014. Removals using no-impact methods (e.g., dry pull) may continue outside the in-water
  work window or would resume under the period of subsequent IHAs (i.e., September 2014).

    The Navy assumes that the contractor will drive approximately two 
steel piles per day, and five concrete or fiberglass piles per day. For 
steel piles, each pile is assumed to require up to two hours of 
driving, including 1-1.5 hours of vibratory pile driving and up to 0.5 
hour of impact pile driving (if necessary). Concrete and fiberglass 
piles would be jetted then driven with an impact pile driver only. 
During the first year of work, approximately 66 non-overlapping days of 
pile driving are expected to occur in the episodes described in Table 
2. Approximately 84 days of demolition work are expected, beginning in 
March 2014. The majority of these 84 days will involve above-water work 
or other no-impact methods and would not impact marine mammals; the 
Navy assumes that approximately one quarter of the days (21 days) might 
involve methods that could cause disturbance to marine mammals.

Description of Sound Sources

    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in Hz or cycles per second. Wavelength is the distance 
between two peaks of a sound wave; lower frequency sounds have longer 
wavelengths than higher frequency sounds and attenuate more rapidly in 
shallower water. Amplitude is the height of the sound pressure wave or 
the `loudness' of a sound and is typically measured using the decibel 
(dB) scale. A dB is the ratio between a measured pressure (with sound) 
and a reference pressure (sound at a constant pressure, established by 
scientific standards). It is a logarithmic unit that accounts for large 
variations in amplitude; therefore, relatively small changes in dB 
ratings correspond to large changes in sound pressure. When referring 
to SPLs (SPLs; the sound force per unit area), sound is referenced in 
the context of underwater sound pressure to 1 microPascal ([mu]Pa). One 
pascal is the pressure resulting from a force of one newton exerted 
over an area of one square meter. The source level represents the sound 
level at a distance of 1 m from the source (referenced to 1 [mu]Pa). 
The received level is the sound level at the listener's position.
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Rms is calculated by squaring all of the 
sound amplitudes, averaging the squares, and then taking the square 
root of the average (Urick, 1983). Rms accounts for both positive and 
negative values; squaring the pressures makes all values positive so 
that they may be accounted for in the summation of pressure levels 
(Hastings and Popper, 2005). This measurement is often used in the 
context of discussing behavioral effects, in part because behavioral 
effects, which often result from auditory cues, may be better expressed 
through averaged units than by peak pressures.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in all 
directions away from the source (similar to ripples on the surface of a 
pond), except in cases where the source is directional. The 
compressions and decompressions

[[Page 30877]]

associated with sound waves are detected as changes in pressure by 
aquatic life and man-made sound receptors such as hydrophones. 
Underwater sound levels (`ambient sound') are comprised of multiple 
sources, including physical (e.g., waves, earthquakes, ice, atmospheric 
sound), biological (e.g., sounds produced by marine mammals, fish, and 
invertebrates), and anthropogenic sound (e.g., vessels, dredging, 
aircraft, construction). Even in the absence of anthropogenic sound, 
the sea is typically a loud environment. A number of sources of sound 
are likely to occur within Hood Canal, including the following 
(Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient noise for frequencies between 200 Hz and 50 
kHz (Mitson, 1995). In general, ambient noise levels tend to increase 
with increasing wind speed and wave height. Surf noise becomes 
important near shore, with measurements collected at a distance of 8.5 
km (5.3 mi) from shore showing an increase of 10 dB in the 100 to 700 
Hz band during heavy surf conditions.
     Precipitation noise: Noise from rain and hail impacting 
the water surface can become an important component of total noise at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times.
     Biological noise: Marine mammals can contribute 
significantly to ambient noise levels, as can some fish and shrimp. The 
frequency band for biological contributions is from approximately 12 Hz 
to over 100 kHz.
     Anthropogenic noise: Sources of ambient noise related to 
human activity include transportation (surface vessels and aircraft), 
dredging and construction, oil and gas drilling and production, seismic 
surveys, sonar, explosions, and ocean acoustic studies (Richardson et 
al., 1995). Shipping noise typically dominates the total ambient noise 
for frequencies between 20 and 300 Hz. In general, the frequencies of 
anthropogenic sounds are below 1 kHz and, if higher frequency sound 
levels are created, they will attenuate (decrease) rapidly (Richardson 
et al., 1995). Known sound levels and frequency ranges associated with 
anthropogenic sources similar to those that would be used for this 
project are summarized in Table 2. Details of each of the sources are 
described in the following text.

                          Table 3--Representative Sound Levels of Anthropogenic Sources
----------------------------------------------------------------------------------------------------------------
                                          Frequency range  Underwater sound level (dB
              Sound source                     (Hz)               re 1 [mu]Pa)                 Reference
----------------------------------------------------------------------------------------------------------------
Small vessels..........................         250-1,000  151 dB rms at 1 m (3.3 ft)  Richardson et al., 1995.
Tug docking gravel barge...............         200-1,000  149 dB rms at 100 m (328    Blackwell and Greene,
                                                            ft).                        2002.
Vibratory driving of 72-in (1.8 m)               10-1,500  180 dB rms at 10 m (33 ft)  Reyff, 2007.
 steel pipe pile.
Impact driving of 36-in steel pipe pile          10-1,500  195 dB rms at 10 m........  Laughlin, 2007.
Impact driving of 66-in cast-in-steel-           10-1,500  195 dB rms at 10 m........  Reviewed in Hastings and
 shell pile.                                                                            Popper, 2005.
----------------------------------------------------------------------------------------------------------------

    In-water construction activities associated with the project would 
include impact pile driving, vibratory pile driving and removal, and 
possibly pneumatic chipping. The sounds produced by these activities 
fall into one of two sound types: Pulsed and non-pulsed (defined in 
next paragraph). The distinction between these two general sound types 
is important because they have differing potential to cause physical 
effects, particularly with regard to hearing (e.g., Ward, 1997 in 
Southall et al., 2007). Please see Southall et al., (2007) for an in-
depth discussion of these concepts.
    Pulsed sounds (e.g., explosions, gunshots, sonic booms, and impact 
pile driving) are brief, broadband, atonal transients (ANSI, 1986; 
Harris, 1998) and occur either as isolated events or repeated in some 
succession. Pulsed sounds are all characterized by a relatively rapid 
rise from ambient pressure to a maximal pressure value followed by a 
decay period that may include a period of diminishing, oscillating 
maximal and minimal pressures. Pulsed sounds generally have an 
increased capacity to induce physical injury as compared with sounds 
that lack these features.
    Non-pulse (intermittent or continuous sounds) can be tonal, 
broadband, or both. Some of these non-pulse sounds can be transient 
signals of short duration but without the essential properties of 
pulses (e.g., rapid rise time). Examples of non-pulse sounds include 
those produced by vessels, aircraft, machinery operations such as 
drilling or dredging, vibratory pile driving, and active sonar systems. 
The duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    Impact hammers operate by repeatedly dropping a heavy piston onto a 
pile to drive the pile into the substrate. Sound generated by impact 
hammers is characterized by rapid rise times and high peak levels, a 
potentially injurious combination (Hastings and Popper, 2005). 
Vibratory hammers install piles by vibrating them and allowing the 
weight of the hammer to push them into the sediment. Vibratory hammers 
produce significantly less sound than impact hammers. Peak SPLs may be 
180 dB or greater, but are generally 10 to 20 dB lower than SPLs 
generated during impact pile driving of the same-sized pile (Oestman et 
al., 2009). Rise time is slower, reducing the probability and severity 
of injury, and sound energy is distributed over a greater amount of 
time (Nedwell and Edwards, 2002; Carlson et al., 2005).

Ambient Sound

    The underwater acoustic environment consists of ambient sound, 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al., 1995). The ambient underwater sound 
level of a region is defined by the total acoustical energy being 
generated by known and unknown sources, including sounds from both 
natural and anthropogenic sources. The sum of the various natural and 
anthropogenic sound sources at any given location and time depends not 
only on the source levels (as determined by current weather conditions 
and levels of biological and shipping activity) but also on the ability 
of sound to propagate through the environment. In turn, sound 
propagation is dependent on the spatially and temporally varying 
properties of the water column and sea floor, and is frequency-
dependent. As a

[[Page 30878]]

result of the dependence on a large number of varying factors, the 
ambient sound levels at a given frequency and location can vary by 10-
20 dB from day to day (Richardson et al., 1995).
    In the vicinity of the project area, the median broadband 
background underwater sound levels have been measured by the Navy at 
123.8 dB re 1 [mu]Pa between 3 Hz and 20 kHz (see Figures 2-4 to 2-6 in 
the Navy's application. The distribution of underwater sound levels was 
relatively uniform, reflecting the active ship traffic passing through 
the navigation channel at all times of day. The sample locations are 
distributed in the project area on either side of the channel in the 
fairly narrow entrance of San Diego Bay proper. Most ship traffic is 
transiting through the vicinity of the fuel pier to berths farther in 
the bay. Higher levels were observationally associated with nearby ship 
movements when the data were collected (refer to the field log in 
Appendix B of the Navy's application), with the exception of Zuniga 
Jetty, where large populations of snapping shrimp are found.

Sound Thresholds

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

Distance to Sound Thresholds

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

TL = B * log10(R1/R2)

Where:

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

This formula neglects loss due to scattering and absorption, which is 
assumed to be zero here. The degree to which underwater sound 
propagates away from a sound source is dependent on a variety of 
factors, most notably by the water bathymetry and presence or absence 
of reflective or absorptive conditions including in-water structures 
and sediments. Spherical spreading occurs in a perfectly unobstructed 
(free-field) environment not limited by depth or water surface, 
resulting in a 6 dB reduction in sound level for each doubling of 
distance from the source (20*log[range]). Cylindrical spreading occurs 
in an environment in which sound propagation is bounded by the water 
surface and sea bottom, resulting in a reduction of 3 dB in sound level 
for each doubling of distance from the source (10*log[range]). A 
practical spreading value of 15 is often used in shallow water 
conditions, such as San Diego Bay, where spreading may start out 
spherically but then end up cylindrically as the sound is constrained 
by the surface and the bottom.
    However, for this request, the Navy consulted with the University 
of Washington Applied Physics Laboratory to develop a site-specific 
model for TL from pile driving at a central point at the project site 
(see Appendix A in the Navy's application). The model is based on 
historical temperature-salinity data and location-dependent bathymetry. 
In the model, TL is the same for different sound source levels and is 
applied to each of the different activities to determine the point at 
which the applicable thresholds are reached as a function of distance 
from the source. The model's predictions result in a slightly lower 
average rate of TL than practical spreading, and hence are 
conservative. We reviewed and approved this approach. Because the model 
is specific to the project area around the fuel pier site, practical 
spreading loss was assumed in modeling sound propagation for pile 
driving at NMAWC (for relocation of the Navy Marine Mammal Program 
facility).
    Underwater sound from pile driving and extraction--The intensity of 
pile driving sounds is greatly influenced by factors such as the type 
of piles, hammers, and the physical environment in which the activity 
takes place. A large quantity of literature regarding SPLs recorded 
from pile driving projects is available for consideration. In order to 
determine reasonable SPLs and their associated affects on marine 
mammals that are likely to result from pile driving at NBPL, studies 
with similar properties to the proposed action were evaluated. Piles to 
be installed include 36- and 48-in steel pipes, 24- and 18-in concrete 
piles, and 16-in fiberglass-concrete piles. In addition, a vibratory 
pile driver could be used in the extraction of 16-in steel, 14-, 16- 
and 24-in concrete, 13-in plastic, and 12-in timber piles. Sound levels 
associated with vibratory pile removal are assumed to be the same as 
those during vibratory installation (Caltrans, 2007)--which is likely a 
conservative assumption--and have been taken into consideration in the 
modeling analysis. Overall, studies which met the following parameters 
were considered: (1) Pile size and materials: Steel pipe piles (30-72 
in diameter); (2) Hammer machinery: Vibratory and impact hammer; and 
(3) Physical environment: shallow depth (less than 100 ft [30 m]).

              Table 4--Underwater SPLs From Monitored Construction Activities Using Impact Hammers
----------------------------------------------------------------------------------------------------------------
                                                                                   Water
       Project and location           Pile size and type          Method           depth        Measured SPLs
----------------------------------------------------------------------------------------------------------------
Mukilteo Test Piles, WA \1\.......  36-in steel pipe.....  Impact..............      7.3 m  195 dB re 1
                                                                                             [micro]Pa (rms) at
                                                                                             10 m.
Richmond-San Rafael Bridge, CA \2\  66-in steel cast-in-   Impact..............        4 m  195 dB re 1
                                     steel shell.                                            [micro]Pa (rms) at
                                                                                             10 m.
Richmond Inner Harbor, CA \2\.....  72-in steel pipe.....  Vibratory...........       ~5 m  180 dB re 1
                                                                                             [micro]Pa (rms) at
                                                                                             10 m.

[[Page 30879]]

 
San Francisco Bay, CA \2\.........  16-24-in concrete....  Impact..............    10-15 m  173-176 dB re 1
                                                                                             [micro]Pa (rms) at
                                                                                             10 m.
Columbia River Crossing, OR/WA \3\  24-48-in steel pipe..  Vibratory extraction       10 m  172 dB re 1
                                                                                             [micro]Pa (rms) at
                                                                                             10 m.
----------------------------------------------------------------------------------------------------------------
Sources: \1\ Laughlin, 2007;
\2\ Oestman et al., 2009;
\3\ Coleman, 2011.

    Driving of non-steel piles produces lower levels of sound than does 
that of steel piles, and extraction of non-steel piles is assumed to 
produce lower sound levels than that of steel piles (Oestman et al., 
2009). We assume here that a reduction of 10-20 dB from the sound 
produced by extraction of steel piles can be assumed for non-steel 
(i.e., concrete, timber, plastic) piles. There are few data regarding 
use of pneumatic chippers or other underwater cutting tools. In a 
previous IHA proposal (NMFS, 2012), we considered a source value of 161 
dB re 1 [mu]Pa (rms) at 1 m for use of a jackhammer (Nedwell and 
Howell, 2004). Here, we conservatively assume that use of these tools 
will produce the same sound levels as vibratory extraction of non-steel 
piles. Underwater sound levels from pile driving for this project are 
therefore assumed to be as follows:
     For 36- and 48-in steel pipes, 195 dB re 1 [mu]Pa (rms) at 
10 m when driven by impact hammer, 180 dB re 1 [mu]Pa (rms) at 10 m 
when driven by vibratory hammer;
     For 24-in concrete piles driven by impact hammer, 176 dB 
re 1 [mu]Pa (rms) at 10 m; and
     For 16- and 18-in concrete piles driven by impact hammer, 
173 dB re 1 [mu]Pa (rms) at 10 m.
     For vibratory removal of steel piles, 172 dB re 1 
[micro]Pa (rms) at 10 m; for vibratory removal/pneumatic chipping of 
non-steel piles, 160 dB re 1 [micro]Pa (rms) at 10 m.

Based on these values and the results of site-specific transmission 
loss modeling, distances to relevant thresholds and associated areas of 
ensonification are presented in Table 5. Predicted distances to 
thresholds for different sources are shown in Figures 6-1 through 6-7 
of the Navy's application. The areas of ensonification reflect the 
conventional assumption that topographical features such as shorelines 
act as a barrier to underwater sound. Although it is known that there 
can be leakage or diffraction around such barriers, it is generally 
accepted practice to model underwater sound propagation from pile 
driving as continuing in a straight line past a shoreline projection 
such as Ballast Point. In contrast, although Zuniga Jetty would likely 
prevent sound propagation east of the jetty, this effect was not 
considered. Hence the projection of sound through the mouth of the bay 
into the open ocean would be truncated along the jetty and narrower in 
reality than shown. The limits of ensonification due to the project are 
assumed to be essentially the same for different pile sizes subject to 
vibratory installation or removal.

                                       Table 5--Distances to Relevant Sound Thresholds and Areas of Ensonification
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Distance to threshold (m) and associated area of ensonification
                                                                  Source level                                    (km\2\)
                          Description                             (dB at 10 m)   -----------------------------------------------------------------------
                                                                                       190 dB            180 dB            160 dB            120 dB
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steel piles, impact...........................................               195        36, 0.0034       452, 0.1477     5,484, 8.5069               n/a
Steel piles, vibratory........................................               180               n/a        14, 0.0004               n/a    6,470, 11.4895
24-in concrete piles..........................................               176               n/a               n/a       505, 0.1914               n/a
16-in concrete-fiberglass piles...............................               173               n/a               n/a       259, 0.0834               n/a
18-in concrete piles \1\ (NMAWC)..............................               173               n/a               n/a        84, 0.0620               n/a
Vibratory extraction, steel...................................               172               n/a               n/a               n/a    6,467, 11.4895
Vibratory extraction/pneumatic chipping, non-steel............               160               n/a               n/a               n/a    6,467, 11.4890
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Practical spreading loss was assumed for pile driving at marine mammal relocation site because site-specific TL model used for sources at fuel pier
  is not applicable.

    Airborne sound from pile installation and removal--Pile driving can 
generate airborne sound that could potentially result in disturbance to 
marine mammals (specifically, pinnipeds) which are hauled out or at the 
water's surface. As a result, the Navy analyzed the potential for 
pinnipeds hauled out or swimming at the surface near NBPL to be exposed 
to airborne SPLs that could result in Level B behavioral harassment. 
Although there is no official airborne sound threshold, NMFS assumes 
for purposes of the MMPA that behavioral disturbance can occur upon 
exposure to sounds above 100 dB re 20 [micro]Pa rms (unweighted) for 
all pinnipeds, except harbor seals. For harbor seals, the threshold is 
90 dB re 20 [micro]Pa rms (unweighted). 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.
    As was discussed for underwater sound from pile driving, the 
intensity of pile driving sounds is greatly influenced by factors such 
as the type of piles, hammers, and the physical environment in which 
the activity takes place. In order to determine reasonable airborne 
SPLs and their associated effects on marine mammals that are likely to 
result from pile driving at NBPL, studies with similar properties to 
the proposed action, as described previously, were evaluated. Table 6 
details representative pile driving activities that have occurred in 
recent years. Due to the similarity of these actions and the Navy's 
proposed

[[Page 30880]]

action, they represent reasonable SPLs which could be anticipated.

                           Table 6--Airborne SPLs From Similar Construction Activities
----------------------------------------------------------------------------------------------------------------
                                   Pile size and
      Project and location              type                Method             Water depth       Measured SPLs
----------------------------------------------------------------------------------------------------------------
Northstar Island, AK \1\.......  42-in steel pipe.  Impact................  Approximately 12   97 dB re 20
                                                                             m.                 [micro]Pa (rms)
                                                                                                at 160 m.
Keystone Ferry Terminal, WA \2\  30-in steel pipe.  Vibratory.............  Approximately 9 m  97 dB re 20
                                                                                                [micro]Pa (rms)
                                                                                                at 13 m.
----------------------------------------------------------------------------------------------------------------
Sources: \1\ Blackwell et al., 2004; \2\ Laughlin, 2010.

    Based on these values and the assumption of spherical spreading 
loss, distances to relevant thresholds and associated areas of 
ensonification are presented in Table 7. The nearest known haul-out 
location for harbor seals is approximately 250 m away and hence would 
be subject to sound levels that may result in behavioral disturbance, 
if animals are present. For sea lions, all airborne distances are less 
than those calculated for underwater sound thresholds, therefore, 
protective measures would be in place out to the distances calculated 
for the underwater thresholds, and the distances for the airborne 
thresholds would be covered fully by mitigation and monitoring measures 
in place for underwater sound thresholds. No sea lion haul-outs or 
rookeries are located within the airborne harassment radii.

           Table 7--Distances to Relevant Sound Thresholds and Areas of Ensonification, Airborne Sound
----------------------------------------------------------------------------------------------------------------
                                                                                Distance to threshold (m) and
                                                          Threshold, re 20    associated area of ensonification
                         Group                               [mu]Pa rms                    (km\2\)
                                                            (unweighted)   -------------------------------------
                                                                              Impact driving   Vibratory driving
----------------------------------------------------------------------------------------------------------------
Harbor seals...........................................              90 dB         358, 0.403          28, 0.002
California sea lions...................................             100 dB         113, 0.040           9, 0.000
----------------------------------------------------------------------------------------------------------------

Description of Marine Mammals in the Area of the Specified Activity

    The Navy has conducted marine mammal surveys in the project area 
beginning in 2007 and continuing through March 2012 (Merkel and 
Associates, Inc., 2008; Johnson, 2010, 2011; Lerma, 2012). Boat survey 
routes (see Figure 3-1 of the Navy's application) established in 2007 
have been resurveyed on 16 occasions, 13 of which were during the 
seasonal window for in-water construction and demolition (September-
April). There are four marine mammal species which are either resident 
or have known seasonal occurrence in San Diego Bay, including the 
California sea lion, harbor seal, bottlenose dolphin, and gray whale. 
Navy records indicate that other species that occur in the Southern 
California Bight may have the potential for isolated occurrence within 
San Diego Bay or just offshore. The Pacific white-sided and common 
dolphin (Lagenorhynchus obliquidens and Delphinus sp., respectively) 
were sighted along a previously used transect on the opposite side of 
the Point Loma peninsula (Merkel & Associates, Inc., 2008), near the 
kelp forests. Risso's dolphin (Grampus griseus) is fairly common in 
southern California coastal waters, but has not been seen in San Diego 
Bay. These species have not been observed near the project area and are 
not expected to occur there, and, given the unlikelihood of their 
exposure to sound generated from the project, are thus not considered 
further. This section summarizes the population status and abundance of 
the four species for which we anticipate exposure to sound from the 
project. We have reviewed the Navy's detailed species descriptions, 
including life history information, for accuracy and completeness and 
refer the reader to Sections 3 and 4 of the Navy's application instead 
of reprinting the information here. Table 7 lists the marine mammal 
species that occur in the vicinity of NBPL. The following information 
is summarized largely from NMFS Stock Assessment Reports.

                             Table 8--Marine Mammals Present in the Vicinity of NBPL
----------------------------------------------------------------------------------------------------------------
                                        Stock abundance \1\     Relative occurrence in
               Species                       (CV, Nmin)          north San Diego Bay      Season of  occurrence
----------------------------------------------------------------------------------------------------------------
California sea lion U.S. stock......  296,750 (n/a, 153,337).  Abundant...............  Year-round.
Harbor seal California stock........  30,196 (0.157, 26,667).  Uncommon, localized....  Year-round.
Bottlenose dolphin California         323....................  Occasional.............  Year-round.
 coastal stock.                       (0.13, 290)............
Gray whale Eastern North Pacific      19,126 (0.07, 18,017)..  Rare, during migration   Late winter.
 stock.                                                         only.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: http://www.nmfs.noaa.gov/pr/sars/species.htm. CV is
  coefficient of variation; Nmin is the minimum estimate of stock abundance.


[[Page 30881]]

California Sea Lion

    California sea lions range from the Gulf of California north to the 
Gulf of Alaska, with breeding areas located in the Gulf of California, 
western Baja California, and southern California. Five genetically 
distinct geographic populations have been identified: (1) Pacific 
Temperate, (2) Pacific Subtropical, (3) Southern Gulf of California, 
(4) Central Gulf of California and (5) Northern Gulf of California 
(Schramm et al., 2009). Rookeries for the Pacific Temperate population 
are found within U.S. waters and just south of the U.S.-Mexico border, 
and animals belonging to this population may be found form the Gulf of 
Alaska to Mexican waters off Baja California. Animals belonging to 
other populations (e.g., Pacific Subtropical) may range into U.S. 
waters during non-breeding periods. For management purposes, a stock of 
California sea lions comprising those animals at rookeries within the 
U.S. is defined (i.e., the U.S. stock of California sea lions) 
(Carretta et al., 2012). Pup production at the Coronado Islands rookery 
in Mexican waters is considered an insignificant contribution to the 
overall size of the Pacific Temperate population (Lowry and Maravilla-
Chavez, 2005).
    California sea lions are not protected under the Endangered Species 
Act (ESA) or listed as depleted under the MMPA. Total annual human-
caused mortality (at least 431) is substantially less than the 
potential biological removal (PBR, estimated at 9,200 per year); 
therefore, California sea lions are not considered a strategic stock 
under the MMPA. There are indications that the California sea lion may 
have reached or is approaching carrying capacity, although more data 
are needed to confirm that leveling in growth persists (Carretta et 
al., 2012).
    The best abundance estimate of the U.S. stock of California sea 
lions is 296,750 and the minimum population size of this stock is 
153,337 individuals (Carretta et al., 2012). The entire population 
cannot be counted because all age and sex classes are never ashore at 
the same time; therefore, the best abundance estimate is determined 
from the number of births and the proportion of pups in the population, 
with censuses conducted in July after all pups have been born. 
Specifically, the pup count for rookeries in southern California from 
2008 was adjusted for pre-census mortality and then multiplied by the 
inverse of the fraction of newborn pups in the population (Carretta et 
al., 2012). The minimum population size was determined from counts of 
all age and sex classes that were ashore at all the major rookeries and 
haul-out sites in southern and central California during the 2007 
breeding season, including all California sea lions counted during the 
July 2007 census at the Channel Islands in southern California and at 
haul-out sites located between Point Conception and Point Reyes, 
California (Carretta et al., 2012). An additional unknown number of 
California sea lions are at sea or hauled out at locations that were 
not censused and are not accounted for in the minimum population size.
    Trends in pup counts from 1975 through 2008 have been assessed for 
four rookeries in southern California and for haul-outs in central and 
northern California. During this time period counts of pups increased 
at an annual rate of 5.4 percent, excluding six El Nino years when pup 
production declined dramatically before quickly rebounding (Carretta et 
al., 2012). The maximum population growth rate was 9.2 percent when pup 
counts from the El Ni[ntilde]o years were removed. However, the 
apparent growth rate from the population trajectory underestimates the 
intrinsic growth rate because it does not consider human-caused 
mortality occurring during the time series; the default maximum net 
productivity rate for pinnipeds (12 percent per year) is considered 
appropriate for California sea lions (Carretta et al., 2012).
    Historic exploitation of California sea lions include harvest for 
food by Native Americans in pre-historic times and for oil and hides in 
the mid-1800s, as well as exploitation for a variety of reasons more 
recently (Carretta et al., 2012). There are few historical records to 
document the effects of such exploitation on sea lion abundance (Lowry 
et al., 1992). Data from 2003-09 indicate that a minimum of 337 (CV = 
0.56) California sea lions are killed annually in commercial fisheries. 
In addition, a summary of stranding database records for 2005-09 shows 
an annual average of 65 such events, which is likely a gross 
underestimate because most carcasses are not recovered. California sea 
lions may also be removed because of predation on endangered salmonids 
(17 per year, 2008-10) or incidentally captured during scientific 
research (3 per year, 2005-09) (Carretta et al., 2012). Sea lion 
mortality has also been linked to the algal-produced neurotoxin domoic 
acid (Scholin et al., 2000). There is currently an Unusual Mortality 
Event (UME) declaration in effect for California sea lions. Future 
mortality may be expected to occur, due to the sporadic occurrence of 
such harmful algal blooms. Beginning in January 2013, elevated 
strandings of California sea lion pups have been observed in Southern 
California, with live sea lion strandings nearly three times higher 
than the historical average. The causes of this UME are under 
investigation (http://www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm; accessed April 10, 2013).
    The California sea lion is by far the most commonly-sighted 
pinniped species at sea or on land in the vicinity of NBPL and northern 
San Diego Bay, where there is a resident non-breeding population. 
California sea lions regularly occur on rocks, buoys and other 
structures, and especially on the bait barges, although numbers vary 
greatly as individuals move between the bay and rookeries on offshore 
islands. Different age classes of California sea lions are found in the 
San Diego region throughout the year (Lowry et al., 1991), although 
Navy surveys show that the local population comprises adult females and 
subadult males and females, with adult males being uncommon. The Navy 
has conducted marine mammal surveys throughout the north San Diego Bay 
project area (Merkel & Associates, Inc., 2008, Johnson, 2010, 2011, 
Lerma, 2012). Sightings include all animals observed and their 
locations (using geographical positioning systems). The majority of 
observations are of animals hauled out.

Harbor Seal

    Harbor seals inhabit coastal and estuarine waters and shoreline 
areas of the northern hemisphere from temperate to polar regions. The 
eastern North Pacific subspecies is found from Baja California north to 
the Aleutian Islands and into the Bering Sea. Multiple lines of 
evidence support the existence of geographic structure among harbor 
seal populations from California to Alaska (Carretta et al., 2012). 
However, because stock boundaries are difficult to meaningfully draw 
from a biological perspective, three separate harbor seal stocks are 
recognized for management purposes along the west coast of the 
continental U.S.: (1) Inland waters of Washington, (2) outer coast of 
Oregon and Washington, and (3) California (Carretta et al., 2012). 
Multiple stocks are recognized in Alaska. Placement of a stock boundary 
at the California-Oregon border is not based on biology but is 
considered a political and jurisdictional convenience (Carretta et al., 
2012). In addition, harbor seals may occur in Mexican waters, but these 
animals are not considered part of the California stock. Only the 
California stock may be found in the project area.

[[Page 30882]]

    California harbor seals are not protected under the ESA or listed 
as depleted under the MMPA, and are not considered a strategic stock 
under the MMPA because annual human-caused mortality (31) is 
significantly less than the calculated PBR (1,600). The population 
appears to be stabilizing at what may be its carrying capacity and the 
fishery mortality is declining.
    The best abundance estimate of the California stock of harbor seals 
is 30,196 (CV = 0.157) and the minimum population size of this stock is 
26,667 individuals (Carretta et al., 2012). The entire population 
cannot be counted because some individuals are always away from haul-
out sites. In addition, complete pup counts are not possible as for 
other species of pinniped because pups are precocious and enter the 
water almost immediately after birth. Therefore, the best abundance 
estimate is estimated by counting the number of seals ashore during the 
peak haul-out period (May to July) and by multiplying this count by a 
correction factor equal to the inverse of the estimated fraction of 
seals on land (Carretta et al., 2012). The current abundance estimate, 
as well as the minimum population size, is based off of haul-out counts 
from 2009.
    Counts of harbor seals in California increased from 1981 to 2004, 
with a calculated annual net productivity rate of 9.2 percent for the 
period 1983-1994 (Carretta et al., 2012). However, maximum net 
productivity rates cannot be estimated because measurements were not 
made when the stock size was very small, and the default maximum net 
productivity rate for pinnipeds (12 percent per year) is considered 
appropriate for harbor seals (Carretta et al., 2012).
    Prior to state and federal protection and especially during the 
nineteenth century, harbor seals along the west coast of North America 
were greatly reduced by commercial hunting, with only a few hundred 
individuals surviving in a few isolated areas along the California 
coast (Carretta et al., 2012). However, in the last half of this 
century, the population has increased dramatically. Data from 2004-09 
indicate that 18 (CV = 0.73) California harbor seals are killed 
annually in commercial fisheries. In addition, California stranding 
database records for 2005-09 shows an annual average of 12 such events, 
which is likely an underestimate because most carcasses are not 
recovered. Two UMEs of harbor seals in California occurred in 1997 and 
2000 with the cause considered to be infectious disease. All west coast 
harbor seals that have been tested for morbilliviruses were found to be 
seronegative, indicating that this disease is not endemic in the 
population and that this population is extremely susceptible to an 
epidemic of this disease (Ham-Lamm[eacute] et al., 1999).
    Harbor seals are relatively uncommon within San Diego Bay, and do 
not have a significant mainland California distribution south of Point 
Mugu. Sightings in the Navy transect surveys of northern San Diego Bay 
cited above were limited to individuals outside of the project area, on 
the south side of Ballast Point. The haul-out area south of Ballast 
Point is only temporary with overwash of the rocks occurring daily; 
primary local harbor seal haul-outs are in La Jolla. With heavy vessel 
traffic and noise in the project area, it is likely that harbor seals 
seen outside the project area at Ballast Point move toward Point Loma 
and preferred foraging habitat rather than actively foraging in or 
transiting the project area on a frequent basis. However, Navy marine 
mammal monitoring for another project conducted intermittently from 
2010-12 has documented several harbor seals near Pier 122 (within the 
project area) at various times, with the greatest number of sightings 
during April and May.

Gray Whale

    Gray whales are found in shallow coastal waters, migrating between 
summer feeding areas in the north and winter breeding areas in the 
south. Gray whales were historically common throughout the northern 
hemisphere but are now found only in the Pacific, where two populations 
are recognized, Eastern and Western North Pacific (ENP and WNP). ENP 
whales breed and calve primarily in areas off Baja California and in 
the Gulf of California. From February to May, whales typically migrate 
northbound to summer/fall feeding areas in the Chukchi and northern 
Bering Seas, with the southbound return to calving areas typically 
occurring in November and December. WNP whales are known to feed in the 
Okhotsk Sea and off of Kamchatka before migrating south to poorly known 
wintering grounds, possibly in the South China Sea.
    The two populations have historically been considered 
geographically isolated from each other; however, recent data from 
satellite-tracked whales indicates that there is some overlap between 
the stocks. Two WNP whales were tracked from Russian foraging areas 
along the Pacific rim to Baja California (Mate et al., 2011), and, in 
one case where the satellite tag remained attached to the whale for a 
longer period, a WNP whale was tracked from Russia to Mexico and back 
again (IWC, 2012). Between 22-24 WNP whales are known to have occurred 
in the eastern Pacific through comparisons of ENP and WNP photo-
identification catalogs (IWC, 2012; Weller et al., 2011; Burdin et al., 
2011), and WNP animals comprised 8.1 percent of gray whales identified 
during a recent field season off of Vancouver Island (Weller et al., 
2012). In addition, two genetic matches of WNP whales have been 
recorded off of Santa Barbara, CA (Lang et al., 2011). Therefore, a 
portion of the WNP population is assumed to migrate, at least in some 
years, to the eastern Pacific during the winter breeding season.
    However, only ENP whales are expected to occur in the project area. 
The likelihood of any gray whale being exposed to project sound to the 
degree considered in this document is already low, as it would require 
a migrating whale to linger for an extended period of time, or for 
multiple migrating whales to linger for shorter periods of time. While 
such an occurrence is not unknown, it is uncommon. Further, of the 
approximately 20,000 gray whales migrating through the Southern 
California Bight, it is extremely unlikely that one found in San Diego 
Bay would be one of the approximately 20 WNP whales that have been 
documented in the eastern Pacific (less than one percent probability). 
The likelihood that a WNP whale would be exposed to elevated levels of 
sound from the specified activities is insignificant and discountable.
    The ENP population of gray whales, which is managed as a stock, was 
removed from ESA protection in 1994, is not currently protected under 
the ESA, and is not listed as depleted under the MMPA. Punt and Wade 
(2010) estimated the ENP population was at 91 percent of carrying 
capacity and at 129 percent of the maximum net productivity level and 
therefore within the range of its optimum sustainable population. The 
ENP stock of gray whales is not classified as a strategic stock under 
the MMPA because the estimated annual level of human-caused mortality 
(128) is less than the calculated PBR (558) (Carretta et al., 2013). 
The WNP population is listed as endangered under the ESA and depleted 
under the MMPA as a foreign stock.
    The best abundance estimate of the ENP stock of gray whales is 
19,126 (CV = 0.071) and the minimum population size of this stock is 
18,017 individuals (Carretta et al., 2013). Systematic counts of gray 
whales migrating south along the central California coast have been 
conducted by shore-based observers since 1967. The best and minimum

[[Page 30883]]

abundance estimates were calculated from 2006-07 survey data, the first 
year in which improved counting techniques and a more consistent 
approach to abundance estimation were used (Carretta et al., 2013). The 
population size of the ENP gray whale stock has been increasing over 
the past several decades despite a west coast UME (unexplained causes) 
from 1999-2001. The estimated annual rate of increase from 1967-88, 
based on the revised abundance time series from Laake et al. (2009), is 
3.2 percent (Punt and Wade, 2010). Based on the same analyses, the best 
estimate of the maximum productivity rate for gray whales is considered 
to be 6.2 percent. The most recent estimate of WNP gray whale abundance 
is 137 individuals (IWC, 2012).
    As noted above, gray whale numbers were significantly reduced by 
whaling, becoming extirpated from the Atlantic by the early 1700s and 
listed as an endangered species in the Pacific. The ENP stock has since 
recovered sufficiently to be delisted from the ESA. Gray whales remain 
subject to occasional fisheries-related mortality and death from ship 
strikes. Based on stranding network data for the period 2006-10, there 
are an average of 0.2 deaths per year from the former and 2.2 per year 
from the latter. In addition, subsistence hunting of gray whales by 
hunters in Russia and the U.S. is approved by the International Whaling 
Commission, although none is currently authorized in the U.S. From 
2006-10, the annual Russian subsistence harvest was 123 whales 
(Carretta et al., 2013). Climate change is considered a significant 
habitat concern for gray whales, as prey composition and distribution 
is likely to be altered and human activity in the whales' summer 
feeding grounds increases (Carretta et al., 2013).
    Peak abundance of gray whales off the coast of San Diego is 
typically during January during the southbound migration and in March 
as whales return north, although females with calves, which depart 
Mexico later than males or females without calves, can be sighted from 
March through May or June (Leatherwood, 1974; Poole, 1984; Rugh et al., 
2001). Gray whales are not expected in the project area except during 
the northward migration, when they are closest to the coast and may be 
infrequently observed offshore of San Diego Bay (Rice et al., 1981). 
Migrating gray whales that do transit nearshore waters would likely be 
traveling, rather than foraging, and would likely be present only 
briefly at typical travel speeds of 3 kn (Perryman et al., 1999, Mate 
and Urb[aacute]n-Ramirez, 2003). Gray whales are known to occur near 
the mouth of San Diego Bay, and occasionally enter the bay. However, 
their occurrence in San Diego Bay is sporadic and unpredictable. In 
recent years, local records show that solitary individuals have entered 
the bay and remained for varying lengths of time during March 2009, 
April 2010, and July 2011. Navy field notes show an occurrence of one 
gray whale that lingered in the northern part of the bay for two weeks.

Bottlenose Dolphin

    Bottlenose dolphins are found worldwide in tropical to temperate 
waters and can be found in all depths from estuarine inshore to deep 
offshore waters. Temperature appears to limit the range of the species, 
either directly, or indirectly, for example, through distribution of 
prey. Off North American coasts, common bottlenose dolphins are found 
where surface water temperatures range from about 10 [deg]C to 32 
[deg]C. In many regions, including California, separate coastal and 
offshore populations are known, with significant genetic 
differentiation evident between the two ecotypes (e.g., Walker, 1981). 
Therefore, two stocks of bottlenose dolphins--coastal and offshore--are 
managed along the west coast. California coastal bottlenose dolphins 
are found within about one kilometer of shore from San Francisco Bay 
south into Mexican waters (Hansen, 1990; Carretta et al., 1998; Defran 
and Weller, 1999). Although there is little site fidelity of coastal 
bottlenose dolphins in California and they are known to move between 
U.S. and Mexican waters, the stock as defined for management purposes 
includes only animals found in U.S. waters. In southern California, 
animals are found within 500 m of the shoreline 99 percent of the time 
and within 250 m 90 percent of the time (Hanson and Defran, 1993). Only 
coastal bottlenose dolphins would be expected to occur at the project 
location.
    California coastal bottlenose dolphins are not protected under the 
MMPA or listed as depleted under the MMPA. The total annual human-
caused mortality for this stock (>=0.2) is less than the calculated PBR 
(2.4) and the stock is not considered strategic under the MMPA.
    The best abundance estimate for California coastal bottlenose 
dolphins is 323 (CV = 0.13, 95% CI 259-430), and the minimum population 
estimate is approximately 290 individuals (Carretta et al., 2009). 
These values are based on photographic mark-recapture surveys conducted 
along the San Diego coast in 2004-05, but are considered likely 
underestimates, as they do not reflect that approximately 35 percent of 
dolphins encountered lack identifiable dorsal fin marks (Defran and 
Weller, 1999). If 35 percent of all animals lack distinguishing marks, 
then the true population size would be closer to 450-500 animals 
(Carretta et al., 2009). Based on a comparison of mark-recapture 
abundance estimates for the periods 1987-89, 1996-98, and 2004-05, 
Dudzik et al. (2006) stated that the population size had remained 
stable over this period. No information on current or maximum net 
productivity rates is available for California coastal bottlenose 
dolphins, and the default maximum annual net growth rate for cetaceans 
(4 percent) is considered appropriate (Carretta et al., 2009).
    Historically, bottlenose dolphins were removed via live-capture for 
display, but no such captures have been documented since 1982 and no 
permits are active. Due to its exclusive use of coastal habitats, the 
California coastal bottlenose dolphin population is susceptible to 
fishery-related mortality in coastal set net fisheries. However, 
because of various fishery closures, the potential for mortality of 
coastal bottlenose dolphins in California set gillnet fisheries has 
been greatly reduced. Records from 2002-06 indicate that a minimum of 
0.2 deaths per year occurred (Carretta et al., 2009). Coastal gillnet 
fisheries exist in Mexico and may take animals from this population, 
but no details are available. Habitat concerns may be an issue for this 
stock, as pollutant levels, especially DDT residues, found in Southern 
California coastal bottlenose dolphins have been found to be among the 
highest of any cetacean examined (O'Shea et al. 1980). Effects of these 
pollutants are not well understood. In addition, California coastal 
bottlenose dolphins may be vulnerable to the effects of morbillivirus 
outbreaks, which have been implicated in mass mortality of bottlenose 
dolphins on the U.S. Atlantic coast (Lipscomb et al. 1994).
    As seen in the Navy's marine mammal surveys of San Diego Bay, cited 
above, coastal bottlenose dolphins have occurred within San Diego Bay 
sporadically and in variable numbers and locations. California coastal 
bottlenose dolphins show little site fidelity and likely move within 
their home range in response to patchy concentrations of nearshore prey 
(Defran et al., 1999, Bearzi et al., 2009). After finding 
concentrations of prey, animals may then forage within a more limited 
spatial extent to take advantage of this local accumulation until such 
time that prey abundance is reduced,

[[Page 30884]]

likely then shifting location once again and possibly covering larger 
distances. Navy surveys frequently result in no observations of 
bottlenose dolphins, and sightings have ranged from 0-8 groups observed 
(0-40 individuals).

Potential Effects of the Specified Activity on Marine Mammals

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

Marine Mammal Hearing

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

Underwater Sound Effects

    Potential Effects of Pile Driving Sound--The effects of sounds from 
pile driving might result in one or more of the following: Temporary or 
permanent hearing impairment, non-auditory physical or physiological 
effects, behavioral disturbance, and masking (Richardson et al., 1995; 
Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007). The 
effects of pile driving on marine mammals are dependent on several 
factors, including the size, type, and depth of the animal; the depth, 
intensity, and duration of the pile driving sound; the depth of the 
water column; the substrate of the habitat; the standoff distance 
between the pile and the animal; and the sound propagation properties 
of the environment. Impacts to marine mammals from pile driving 
activities are expected to result primarily from acoustic pathways. As 
such, the degree of effect is intrinsically related to the received 
level and duration of the sound exposure, which are in turn influenced 
by the distance between the animal and the source. The further away 
from the source, the less intense the exposure should be. The substrate 
and depth of the habitat affect the sound propagation properties of the 
environment. Shallow environments are typically more structurally 
complex, which leads to rapid sound attenuation. In addition, 
substrates that are soft (e.g., sand) would absorb or attenuate the 
sound more readily than hard substrates (e.g., rock) which may reflect 
the acoustic wave. Soft porous substrates would also likely require 
less time to drive the pile, and possibly less forceful equipment, 
which would ultimately decrease the intensity of the acoustic source.
    In the absence of mitigation, impacts to marine species would be 
expected to result from physiological and behavioral responses to both 
the type and strength of the acoustic signature (Viada et al., 2008). 
The type and severity of behavioral impacts are more difficult to 
define due to limited studies addressing the behavioral effects of 
impulsive sounds on marine mammals. Potential effects from impulsive 
sound sources can range in severity, ranging from effects such as 
behavioral disturbance, tactile perception, physical discomfort, slight 
injury of the internal organs and the auditory system, to mortality 
(Yelverton et al., 1973).
    Hearing Impairment and Other Physical Effects--Marine mammals 
exposed to high intensity sound repeatedly or for prolonged periods can 
experience hearing threshold shift (TS), which is the loss of hearing 
sensitivity at certain frequency ranges (Kastak et al., 1999; Schlundt 
et al., 2000; Finneran et al., 2002, 2005). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not recoverable, or 
temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Marine mammals depend on 
acoustic cues for vital biological functions, (e.g., orientation, 
communication, finding prey, avoiding predators); thus, TTS may result 
in reduced fitness in survival and reproduction. However, this depends 
on the frequency and duration of TTS, as well as the biological context 
in which it occurs. TTS of limited duration, occurring in a frequency 
range that does not coincide with that used for recognition of 
important acoustic cues, would have little to no effect on an animal's 
fitness. Repeated sound exposure that leads to TTS could cause PTS. 
PTS, in the unlikely event that it occurred, would constitute injury, 
but TTS is not considered injury (Southall et al., 2007). It is 
unlikely that the project would result in any cases of temporary or 
especially permanent hearing impairment or any significant non-auditory 
physical or physiological effects for reasons discussed later in this 
document. Some behavioral disturbance is expected, but it is likely 
that this would be localized and short-term because of the short 
project duration.
    Several aspects of the planned monitoring and mitigation measures 
for this project (see the ``Proposed Mitigation'' and ``Proposed 
Monitoring and Reporting'' sections later in this document) are 
designed to detect marine mammals occurring near the pile driving to 
avoid exposing them to sound pulses that might, in theory, cause 
hearing impairment. In addition, many

[[Page 30885]]

cetaceans are likely to show some avoidance of the area where received 
levels of pile driving sound are high enough that hearing impairment 
could potentially occur. In those cases, the avoidance responses of the 
animals themselves would reduce or (most likely) avoid any possibility 
of hearing impairment. Non-auditory physical effects may also occur in 
marine mammals exposed to strong underwater pulsed sound. It is 
especially unlikely that any effects of these types would occur during 
the present project given the brief duration of exposure for any given 
individual and the planned monitoring and mitigation measures. The 
following subsections discuss in somewhat more detail the possibilities 
of TTS, PTS, and non-auditory physical effects.
    Temporary Threshold Shift--TTS is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing TTS, the hearing threshold rises, and a sound 
must be stronger in order to be heard. In terrestrial mammals, TTS can 
last from minutes or hours to days (in cases of strong TTS). For sound 
exposures at or somewhat above the TTS threshold, hearing sensitivity 
in both terrestrial and marine mammals recovers rapidly after exposure 
to the sound ends. Few data on sound levels and durations necessary to 
elicit mild TTS have been obtained for marine mammals, and none of the 
published data concern TTS elicited by exposure to multiple pulses of 
sound. Available data on TTS in marine mammals are summarized in 
Southall et al. (2007).
    Given the available data, the received level of a single pulse 
(with no frequency weighting) might need to be approximately 186 dB re 
1 [mu]Pa\2\-s (i.e., 186 dB sound exposure level [SEL] or approximately 
221-226 dB pk-pk) in order to produce brief, mild TTS. Exposure to 
several strong pulses that each have received levels near 190 dB re 1 
[mu]Pa rms (175-180 dB SEL) might result in cumulative exposure of 
approximately 186 dB SEL and thus slight TTS in a small odontocete, 
assuming the TTS threshold is (to a first approximation) a function of 
the total received pulse energy. Levels greater than or equal to 190 dB 
re 1 [mu]Pa rms are expected to be restricted to radii no more than 5 m 
(16 ft) from the pile driving. For an odontocete closer to the surface, 
the maximum radius with 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 and beluga whale (Delphinapterus leucas). 
There is no published TTS information for other species of cetaceans. 
However, preliminary evidence from a harbor porpoise exposed to pulsed 
sound suggests that its TTS threshold may have been lower (Lucke et 
al., 2009). To avoid the potential for injury, NMFS has determined that 
cetaceans should not be exposed to pulsed underwater sound at received 
levels exceeding 180 dB re 1 [mu]Pa rms. As summarized above, data that 
are now available imply that TTS is unlikely to occur unless 
odontocetes are exposed to pile driving pulses stronger than 180 dB re 
1 [mu]Pa rms.
    Permanent Threshold Shift--When PTS occurs, there is physical 
damage to the sound receptors in the ear. In severe cases, there can be 
total or partial deafness, while in other cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985). There is no specific evidence that exposure to pulses of sound 
can cause PTS in any marine mammal. However, given the possibility that 
mammals close to pile driving activity might incur TTS, there has been 
further speculation about the possibility that some individuals 
occurring very close to pile driving might incur PTS. Single or 
occasional occurrences of mild TTS are not indicative of permanent 
auditory damage, but repeated or (in some cases) single exposures to a 
level well above that causing TTS onset might elicit PTS.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several decibels above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time. Based on data from 
terrestrial mammals, a precautionary assumption is that the PTS 
threshold for impulse sounds (such as pile driving pulses as received 
close to the source) is at least 6 dB higher than the TTS threshold on 
a peak-pressure basis and probably greater than 6 dB (Southall et al., 
2007). On an SEL basis, Southall et al. (2007) estimated that received 
levels would need to exceed the TTS threshold by at least 15 dB for 
there to be risk of PTS. Thus, for cetaceans, Southall et al. (2007) 
estimate that the PTS threshold might be an M-weighted SEL (for the 
sequence of received pulses) of approximately 198 dB re 1 [mu]Pa\2\-s 
(15 dB higher than the TTS threshold for an impulse). Given the higher 
level of sound necessary to cause PTS as compared with TTS, it is 
considerably less likely that PTS could occur.
    Measured source levels from impact pile driving can be as high as 
214 dB re 1 [mu]Pa at 1 m (3.3 ft). Although no marine mammals have 
been shown to experience TTS or PTS as a result of being exposed to 
pile driving activities, captive bottlenose dolphins and beluga whales 
exhibited changes in behavior when exposed to strong pulsed sounds 
(Finneran et al., 2000, 2002, 2005). The animals tolerated high 
received levels of sound before exhibiting aversive behaviors. 
Experiments on a beluga whale showed that exposure to a single watergun 
impulse at a received level of 207 kPa (30 psi) p-p, which is 
equivalent to 228 dB p-p re 1 [mu]Pa, resulted in a 7 and 6 dB TTS in 
the beluga whale at 0.4 and 30 kHz, respectively. Thresholds returned 
to within 2 dB of the pre-exposure level within four minutes of the 
exposure (Finneran et al., 2002). Although the source level of pile 
driving from one hammer strike is expected to be much lower than the 
single watergun impulse cited here, animals being exposed for a 
prolonged period to repeated hammer strikes could receive more sound 
exposure in terms of SEL than from the single watergun impulse 
(estimated at 188 dB re 1 [mu]Pa\2\-s) in the aforementioned experiment 
(Finneran et al., 2002). However, in order for marine mammals to 
experience TTS or PTS, the animals have to be close enough to be 
exposed to high intensity sound levels for a prolonged period of time. 
Based on the best scientific information available, these SPLs are far 
below the thresholds that could cause TTS or the onset of PTS.
    Non-auditory Physiological Effects--Non-auditory physiological 
effects or injuries that could theoretically 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 such ways. Marine mammals that

[[Page 30886]]

show behavioral avoidance of pile driving, including some odontocetes 
and some pinnipeds, are especially unlikely to incur auditory 
impairment or non-auditory physical effects.

Disturbance Reactions

    Disturbance includes a variety of effects, including subtle changes 
in behavior, more conspicuous changes in activities, and displacement. 
Behavioral responses to sound are highly variable and context-specific 
and reactions, if any, depend on species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day, and many other factors (Richardson et al., 1995; Wartzok 
et al., 2003/2004; Southall et al., 2007).
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003/04). Animals are most likely to habituate 
to sounds that are predictable and unvarying. The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. Behavioral state may affect the type of response as well. For 
example, animals that are resting may show greater behavioral change in 
response to disturbing sound levels than animals that are highly 
motivated to remain in an area for feeding (Richardson et al., 1995; 
NRC, 2003; Wartzok et al., 2003/04).
    Controlled experiments with captive marine mammals showed 
pronounced behavioral reactions, including avoidance of loud sound 
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed 
responses of wild marine mammals to loud pulsed sound sources 
(typically seismic guns or acoustic harassment devices, but also 
including pile driving) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Morton and 
Symonds, 2002; Thorson and Reyff, 2006; see also Gordon et al., 2004; 
Wartzok et al., 2003/04; Nowacek et al., 2007). Responses to continuous 
sound, such as vibratory pile installation, have not been documented as 
well as responses to pulsed sounds.
    With both types of pile driving, it is likely that the onset of 
pile driving could result in temporary, short term changes in an 
animal's typical behavior and/or avoidance of the affected area. These 
behavioral changes may include (Richardson et al., 1995): Changing 
durations of surfacing and dives, number of blows per surfacing, or 
moving direction and/or speed; reduced/increased vocal activities; 
changing/cessation of certain behavioral activities (such as 
socializing or feeding); visible startle response or aggressive 
behavior (such as tail/fluke slapping or jaw clapping); avoidance of 
areas where sound sources are located; and/or flight responses (e.g., 
pinnipeds flushing into water from haul-outs or rookeries). Pinnipeds 
may increase their haul-out time, possibly to avoid in-water 
disturbance (Thorson and Reyff, 2006). Since pile driving would likely 
only occur for a few hours a day, over a short period of time, it is 
unlikely to result in permanent displacement. Any potential impacts 
from pile driving activities could be experienced by individual marine 
mammals, but would not be likely to cause population level impacts, or 
affect the long-term fitness of the species.
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be expected to be biologically significant if the 
change affects growth, survival, or reproduction. Significant 
behavioral modifications that could potentially lead to effects on 
growth, survival, or reproduction include:
     Drastic changes in diving/surfacing patterns (such as 
those thought to be causing beaked whale stranding due to exposure to 
military mid-frequency tactical sonar);
     Habitat abandonment due to loss of desirable acoustic 
environment; and
     Cessation of feeding or social interaction.
    The onset of behavioral disturbance from anthropogenic sound 
depends on both external factors (characteristics of sound sources and 
their paths) and the specific characteristics of the receiving animals 
(hearing, motivation, experience, demography) and is difficult to 
predict (Southall et al., 2007).

Auditory Masking

    Natural and artificial sounds can disrupt behavior by masking, or 
interfering with, a marine mammal's ability to hear other sounds. 
Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher levels. Chronic exposure to excessive, though not high-
intensity, sound could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions. 
Masking can interfere with detection of acoustic signals such as 
communication calls, echolocation sounds, and environmental sounds 
important to marine mammals. Therefore, under certain circumstances, 
marine mammals whose acoustical sensors or environment are being 
severely masked could also be impaired from maximizing their 
performance fitness in survival and reproduction. If the coincident 
(masking) sound were man-made, it could be potentially harassing if it 
disrupted hearing-related behavior. It is important to distinguish TTS 
and PTS, which persist after the sound exposure, from masking, which 
occurs during the sound exposure. Because masking (without resulting in 
TS) is not associated with abnormal physiological function, it is not 
considered a physiological effect, but rather a potential behavioral 
effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. Because sound 
generated from in-water pile driving is mostly concentrated at low 
frequency ranges, it may have less effect on high frequency 
echolocation sounds made by porpoises. However, lower frequency man-
made sounds are more likely to affect detection of communication calls 
and other potentially important natural sounds such as surf and prey 
sound. It may also affect communication signals when they occur near 
the sound band and thus reduce the communication space of animals 
(e.g., Clark et al., 2009) and cause increased stress levels (e.g., 
Foote et al., 2004; Holt et al., 2009).
    Masking has the potential to impact species at population, 
community, or even ecosystem levels, as well as at individual levels. 
Masking affects both senders and receivers of the signals and can 
potentially have long-term chronic effects on marine mammal species and 
populations. Recent research suggests that low frequency ambient sound 
levels have increased by as much as 20 dB (more than three times in 
terms of SPL) in the world's ocean from pre-industrial periods, and 
that most of these increases are from distant shipping (Hildebrand, 
2009). All anthropogenic sound sources, such as those from vessel 
traffic, pile driving, and dredging activities, contribute to the 
elevated ambient sound levels, thus intensifying masking. However, the 
sum of sound from the proposed activities is confined in an area of 
inland waters (San Diego Bay) that is bounded by landmass; therefore, 
the sound generated is not expected to contribute to increased ocean 
ambient sound.
    The most intense underwater sounds in the proposed action are those 
produced by impact pile driving. Given that the energy distribution of 
pile

[[Page 30887]]

driving covers a broad frequency spectrum, sound from these sources 
would likely be within the audible range of marine mammals present in 
the project area. Impact pile driving activity is relatively short-
term, with rapid pulses occurring for approximately fifteen minutes per 
pile. The probability for impact pile driving resulting from this 
proposed action masking acoustic signals important to the behavior and 
survival of marine mammal species is likely to be negligible. Vibratory 
pile driving is also relatively short-term, with rapid oscillations 
occurring for approximately one and a half hours per pile. It is 
possible that vibratory pile driving resulting from this proposed 
action may mask acoustic signals important to the behavior and survival 
of marine mammal species, but the short-term duration and limited 
affected area would result in insignificant impacts from masking. Any 
masking event that could possibly rise to Level B harassment under the 
MMPA would occur concurrently within the zones of behavioral harassment 
already estimated for vibratory and impact pile driving, and which have 
already been taken into account in the exposure analysis.

Airborne Sound Effects

    Marine mammals that occur in the project area could be exposed to 
airborne sounds associated with pile driving that have the potential to 
cause harassment, depending on their distance from pile driving 
activities. Airborne pile driving sound would have less impact on 
cetaceans than pinnipeds because sound from atmospheric sources does 
not transmit well underwater (Richardson et al., 1995); thus, airborne 
sound would only be an issue for hauled-out pinnipeds in the project 
area. Most likely, airborne sound would cause behavioral responses 
similar to those discussed above in relation to underwater sound. For 
instance, anthropogenic sound could cause hauled-out pinnipeds to 
exhibit changes in their normal behavior, such as reduction in 
vocalizations, or cause them to temporarily abandon their habitat and 
move further from the source. Studies by Blackwell et al. (2004) and 
Moulton et al. (2005) indicate a tolerance or lack of response to 
unweighted airborne sounds as high as 112 dB peak and 96 dB rms.

Anticipated Effects on Habitat

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

Pile Driving Effects on Potential Prey (Fish)

    Construction activities would produce both pulsed (i.e., impact 
pile driving) and continuous (i.e., vibratory pile driving) sounds. 
Fish react to sounds which are especially strong and/or intermittent 
low-frequency sounds. Short duration, sharp sounds can cause overt or 
subtle changes in fish behavior and local distribution. Hastings and 
Popper (2005, 2009) identified several studies that suggest fish may 
relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving (or other types of continuous 
sounds) on fish, although several are based on studies in support of 
large, multiyear bridge construction projects (e.g., Scholik and Yan, 
2001, 2002; Popper and Hastings, 2009). Sound pulses at received levels 
of 160 dB re 1 [mu]Pa may cause subtle changes in fish behavior. SPLs 
of 180 dB may cause noticeable changes in behavior (Pearson et al., 
1992; Skalski et al., 1992). SPLs of sufficient strength may cause 
injury to fish and fish mortality. The most likely impact to fish from 
pile driving activities at the project area would be temporary 
behavioral avoidance of the area. The duration of fish avoidance of 
this area after pile driving stops is unknown, but a rapid return to 
normal recruitment, distribution and behavior is anticipated. In 
general, impacts to marine mammal prey species are expected to be minor 
and temporary due to the short timeframe for the pier replacement 
project.

Pile Driving Effects on Potential Foraging Habitat

    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 vicinity of San Diego Bay.
    Given the short daily duration of sound associated with individual 
pile driving events and the relatively small areas being affected, pile 
driving activities associated with the proposed action are not likely 
to have a permanent, adverse effect on any fish habitat, or populations 
of fish species. Therefore, pile driving is not likely to have a 
permanent, adverse effect on marine mammal foraging habitat at the 
project area.

Proposed Mitigation

    In order to issue an incidental take authorization (ITA) under 
Section 101(a)(5)(D) of the MMPA, we must, where applicable, set forth 
the permissible methods of taking pursuant to such activity, and other 
means of effecting the least practicable impact on such species or 
stock and its habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance, and on the availability of 
such species or stock for taking for certain subsistence uses (where 
relevant).
    Proxy source measurements and site-specific modeling of spreading 
loss (with the exception of the MMP relocation site, where practical 
spreading loss was assumed) were used to estimate zones of influence 
(ZOIs; see ``Estimated Take by Incidental Harassment''); these values 
were used to develop mitigation measures for pile driving activities at 
NBPL. The ZOIs effectively represent the mitigation zone that would be 
established around each pile to prevent Level A harassment to marine 
mammals, while providing estimates of the areas within which Level B 
harassment might occur. In addition to the measures described later in 
this section, the Navy would employ the following standard mitigation 
measures:
    (a) Conduct briefings between construction supervisors and crews, 
marine mammal monitoring team, acoustical monitoring team, and Navy 
staff prior to the start of all pile driving activity, and when new 
personnel join the work, in order to explain responsibilities, 
communication procedures, marine mammal monitoring protocol, and 
operational procedures.

[[Page 30888]]

    (b) Comply with applicable equipment sound standards and ensure 
that all construction equipment has sound control devices no less 
effective than those provided on the original equipment.
    (c) For in-water heavy machinery work with the potential to affect 
marine mammals (other than pile driving), if a marine mammal comes 
within 10 m, operations shall cease and vessels shall reduce speed to 
the minimum level required to maintain steerage and safe working 
conditions. This type of work could include the following activities: 
(1) Movement of the barge to the pile location and (2) removal of the 
pile from the water column/substrate via a crane (i.e., deadpull). For 
these activities, monitoring would take place from 15 minutes prior to 
initiation until the action is complete.

Monitoring and Shutdown for Pile Driving

    The following measures would apply to the Navy's mitigation through 
shutdown and disturbance zones:
    Shutdown Zone--For all pile driving and removal activities, the 
Navy will establish a shutdown zone intended to contain the area in 
which SPLs equal or exceed the 180/190 dB rms acoustic injury criteria. 
The purpose of a shutdown zone is to define an area within which 
shutdown of activity would occur upon sighting of a marine mammal (or 
in anticipation of an animal entering the defined area), thus 
preventing injury, serious injury, or death of marine mammals. Radial 
distances for shutdown zones are shown in Table 5. For certain pile 
types or techniques, the shutdown zone would not exist because source 
levels are lower than the threshold (see Table 5). However, a minimum 
shutdown zone of 10 m will be established during all pile driving and 
removal activities, regardless of the estimated zone. These 
precautionary measures are intended to prevent the already unlikely 
possibility of physical interaction with construction equipment and to 
further reduce any possibility of acoustic injury.
    Disturbance Zone--Disturbance zones are typically defined as the 
area in which SPLs equal or exceed 160 or 120 dB rms (for pulsed or 
non-pulsed sound, respectively). Disturbance zones provide utility for 
monitoring conducted for mitigation purposes (i.e., shutdown zone 
monitoring) by establishing monitoring protocols for areas adjacent to 
the shutdown zones. Monitoring of disturbance zones enables observers 
to be aware of and communicate the presence of marine mammals in the 
project area but outside the shutdown zone and thus prepare for 
potential shutdowns of activity. However, the primary purpose of 
disturbance zone monitoring is for documenting incidents of Level B 
harassment; disturbance zone monitoring is discussed in greater detail 
later (see ``Proposed Monitoring and Reporting''). Nominal radial 
distances for disturbance zones are shown in Table 5 and Table 7 (for 
airborne sound). As with any such large action area, it is impossible 
to guarantee that all animals would be observed or to make 
comprehensive observations of fine-scale behavioral reactions to sound.
    In order to document observed incidences of harassment, monitors 
record all marine mammal observations, regardless of location. The 
observer's location, as well as the location of the pile being driven, 
is known from a GPS. The location of the animal is estimated as a 
distance from the observer, which is then compared to the location from 
the pile. If acoustic monitoring is being conducted for that pile, a 
received SPL may be estimated, or the received level may be estimated 
on the basis of past or subsequent acoustic monitoring. It may then be 
determined whether the animal was exposed to sound levels constituting 
incidental harassment in post-processing of observational and acoustic 
data, and a precise accounting of observed incidences of harassment 
created. Therefore, although the predicted distances to behavioral 
harassment thresholds are useful for estimating incidental harassment 
for purposes of authorizing levels of incidental take, actual take may 
be determined in part through the use of empirical data. That 
information may then be used to extrapolate observed takes to reach an 
approximate understanding of actual total takes.
    Monitoring Protocols--Monitoring would be conducted before, during, 
and after pile driving activities. In addition, observers shall record 
all incidences of marine mammal occurrence, regardless of distance from 
activity, and shall document any behavioral reactions in concert with 
distance from piles being driven. Observations made outside the 
shutdown zone will not result in shutdown; that pile segment would be 
completed without cessation, unless the animal approaches or enters the 
shutdown zone, at which point all pile driving activities would be 
halted. Please see the Marine Mammal Monitoring Plan (available at 
http://www.nmfs.noaa.gov/pr/permits/incidental.htm), developed by the 
Navy in agreement with us, for full details of the monitoring 
protocols. Monitoring will take place from 15 minutes prior to 
initiation through 15 minutes post-completion of pile driving 
activities. Pile driving activities include the time to remove a single 
pile or series of piles, as long as the time elapsed between uses of 
the pile driving equipment is no more than 30 minutes.
    The following additional measures apply to visual monitoring:
    (1) Monitoring will be conducted by qualified observers, who will 
be placed at the best vantage point(s) practicable (as defined in the 
Navy's Marine Mammal Monitoring Plan) to monitor for marine mammals and 
implement shutdown/delay procedures when applicable by calling for the 
shutdown to the hammer operator. Qualified observers are trained 
biologists, with the following minimum qualifications:
     Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target;
     Advanced education in biological science, wildlife 
management, mammalogy, or related fields (bachelor's degree or higher 
is required);
     Experience and ability to conduct field observations and 
collect data according to assigned protocols (this may include academic 
experience);
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates and times when in-water construction 
activities were suspended to avoid potential incidental injury from 
construction sound of marine mammals observed within a defined shutdown 
zone; and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    (2) Prior to the start of pile driving activity, the shutdown zone 
will be monitored for 15 minutes to ensure that it is clear of marine 
mammals. Pile driving will only commence once observers have declared 
the shutdown zone clear of marine mammals; animals will be allowed to 
remain in the

[[Page 30889]]

shutdown zone (i.e., must leave of their own volition) and their 
behavior will be monitored and documented. The shutdown zone may only 
be declared clear, and pile driving started, when the entire shutdown 
zone is visible (i.e., when not obscured by dark, rain, fog, etc.). In 
addition, if such conditions should arise during impact pile driving 
that is already underway, the activity would be halted.
    (3) If a marine mammal approaches or enters the shutdown zone 
during the course of pile driving operations, activity will be halted 
and delayed until either the animal has voluntarily left and been 
visually confirmed beyond the shutdown zone or 15 minutes have passed 
without re-detection of the animal. Monitoring will be conducted 
throughout the time required to drive a pile.

Sound Attenuation Devices

    The use of bubble curtains to reduce underwater sound from impact 
pile driving was considered but is not proposed. Use of a bubble 
curtain in a channel with substantial current may not be effective, as 
unconfined bubbles are likely to be swept away and confined curtain 
systems may be difficult to deploy effectively in high currents. Data 
gathered during monitoring of construction on the San Francisco-Oakland 
Bay Bridge indicated that no reduction in the overall linear sound 
level resulted from use of a bubble curtain in deep water with 
relatively strong current, and the distance to the 190 dB zone was 
considered to be the same with and without the bubble curtain 
(Illingworth & Rodkin, Inc., 2001). During project monitoring for pile 
driving associated with the Richmond-San Rafael Bridge, also in San 
Francisco Bay, it was observed that performance in moderate current was 
significantly reduced (Oestman et al., 2009). Lucke et al. (2011) also 
note that the effectiveness of most currently used curtain designs may 
be compromised in stronger currents and greater water depths. We 
believe that conditions (relatively deep water and strong tidal 
currents of up to 3 kn) at the project site would disperse the bubbles 
and compromise the effectiveness of sound attenuation.

Timing Restrictions

    The Navy has set timing restrictions for pile driving activities to 
avoid in-water work when least tern populations are most likely to be 
foraging and nesting. The in-water work window for avoiding negative 
impacts to terns is September 16-March 31.

Soft-Start

    The use of a soft-start procedure is believed to provide additional 
protection to marine mammals by warning or providing a chance to leave 
the area prior to the hammer operating at full capacity. The pier 
replacement project will utilize soft-start techniques (ramp-up and dry 
fire) for impact and vibratory pile driving. The soft-start requires 
contractors to initiate sound from vibratory hammers for fifteen 
seconds at reduced energy followed by a 30-second waiting period. This 
procedure is repeated two additional times. For impact driving, 
contractors will be required to provide an initial set of three strikes 
from the impact hammer at 40 percent energy, followed by a 30-second 
waiting period, then two subsequent three strike sets.

Daylight Construction

    All pile driving would be conducted only during daylight hours.
    We have carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that we prescribe the means of effecting the least practicable 
impact on the affected marine mammal species and stocks and their 
habitat. Our evaluation of potential measures included consideration of 
the following factors in relation to one another: (1) The manner in 
which, and the degree to which, the successful implementation of the 
measure is expected to minimize adverse impacts to marine mammals; (2) 
the proven or likely efficacy of the specific measure to minimize 
adverse impacts as planned; and (3) the practicability of the measure 
for applicant implementation, including consideration of personnel 
safety, and practicality of implementation.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered, we have preliminarily determined 
that the proposed mitigation measures provide the means of effecting 
the least practicable impact on marine mammal species or stocks and 
their habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance.

Proposed Monitoring and Reporting

    In order to issue an ITA for an activity, section 101(a)(5)(D) of 
the MMPA states that we must, where applicable, set forth 
``requirements pertaining to the monitoring and reporting of such 
taking.'' The MMPA implementing regulations at 50 CFR 216.104 (a)(13) 
indicate that requests for ITAs must include the suggested means of 
accomplishing the necessary monitoring and reporting that would result 
in increased knowledge of the species and of the level of taking or 
impacts on populations of marine mammals that are expected to be 
present in the proposed action area. Please see the Navy's Acoustic and 
Marine Mammal Monitoring Plan for full details of the requirements for 
monitoring and reporting. We have preliminarily determined this 
monitoring plan, which is summarized here, to be sufficient to meet the 
MMPA's monitoring and reporting requirements.

Acoustic Measurements

    The primary purpose of acoustic monitoring is to empirically verify 
modeled injury and behavioral disturbance zones for marine mammals. The 
Navy will determine actual distances to the 160-, 180-, and 190-dB 
zones for underwater sound (where applicable) and to the 90- and 100-dB 
zones for airborne sound. For non-pulsed sound, distances will be 
determined for attenuation to the greater of either the 120-dB 
threshold or to the point at which sound becomes indistinguishable from 
background levels. Acoustic monitoring will be conducted with the 
following objectives:
    (1) Indicator Pile Program (IPP)--Implement a robust in-situ 
monitoring effort to measure sound pressure levels from different 
project activities, including impact and vibratory driving of 36- and 
48-in piles, and to validate the Navy's site-specific transmission loss 
modeling effort.
    (2) Conduct acoustic monitoring for vibratory pile extraction and 
for pneumatic chipping, if used.
    (3) Continue the Navy's collection of ambient underwater sound 
measurements in the absence of project activities to develop a rigorous 
baseline for the San Diego Bay region.
    It is assumed that the measured contours will be significantly 
reduced compared to the conservatively modeled ZOIs. As statistically 
robust results from acoustic monitoring become available, marine mammal 
mitigation zones would be revised as necessary to encompass actual ZOIs 
in subsequent years of the fuel pier replacement project. However, 
should substantial discrepancies become evident through limited data 
processing, the Navy will contact NMFS to propose and discuss 
appropriate changes in monitoring. Acoustic monitoring will be 
conducted in accordance with the approved Acoustic and Marine Mammal 
Monitoring Plan

[[Page 30890]]

developed by the Navy. Notional monitoring locations are shown in 
Figures 3-1 and 3-2 of the Navy's Plan. Please see that plan, available 
at http://www.nmfs.noaa.gov/pr/permits/incidental.htm, for full details 
of the required acoustic monitoring.
    Some details of the methodology include:
     Hydroacoustic monitoring will be conducted for each 
different type of pile and each different method of installation and 
removal. Monitoring will occur across a representative range of 
locations with special attention given to the 120-, 160-, 180-, and 
190-dB ZOI contours. The resulting data set will be analyzed to provide 
a statistically robust characterization of the sound source levels and 
transmission loss associated with different types of pile driving and 
removal activities.
     For underwater recordings, hydrophone systems with the 
ability to measure real time SPLs will be used in accordance with NMFS' 
most recent guidance for the collection of source levels.
     For airborne recordings, to the extent that logistics and 
security allow, reference recordings will be collected at approximately 
50 ft (15.2 m) from the source via a sound meter with integrated 
microphone placed on a tripod 5 ft above the ground. Other distances 
may also be utilized to obtain better data if the signal cannot be 
isolated clearly due to other sound sources (i.e., barges or 
generators). If from a distance other than 50 ft, the source data would 
be converted to the 50-ft distance based on simple spherical spreading.
     Hydrophones will be placed 10 m from the source and within 
the ZOIs to their predicted eastern and southern limits. An integrated 
DGPS will record the location of individual acoustic records. A depth 
sounder or weighted tape measure will be used to determine the depth of 
the water. The hydrophone will be attached to a weighted line to 
maintain a constant depth.
     Each hydrophone (underwater) and microphone (airborne) 
will be calibrated at the beginning of each day of monitoring activity. 
Pressure and intensity levels will be reported relative to 1 [mu]Pa and 
1 [mu]Pa\2\, respectively.
     For each monitored location, a hydrophone will be deployed 
at mid-depth in order to evaluate site specific attenuation and 
propagation characteristics.
     In order to determine the area encompassed by the relevant 
isopleths for marine mammals, hydrophones will collect data at various 
distances from the source to measure attenuation throughout the ZOIs.
     Ambient conditions, both airborne and underwater, would be 
measured at the same monitoring locations but in the absence of project 
sound to determine background sound levels. Ambient levels are intended 
to be recorded over the frequency range from 7 Hz to 20 kHz. Ambient 
conditions will be recorded for at least one minute every hour of the 
work day, for at least one week of each month of the period of the IHA.
     Sound levels associated with soft-start techniques will 
also be measured but will be differentiated from source level 
measurements.
     Airborne levels would be recorded as unweighted, as well 
as in dBA and the distance to marine mammal injury and behavioral 
disturbance thresholds, also referred to as shutdown and buffer zones, 
would be measured.
     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, etc.).

Visual Marine Mammal Observations

    The Navy will collect sighting data and behavioral responses to 
construction for marine mammal species observed in the region of 
activity during the period of activity. All observers will be trained 
in marine mammal identification and behaviors and are required to have 
no other construction-related tasks while conducting monitoring. The 
Navy will monitor the shutdown zone and disturbance zone before, 
during, and after pile driving as described under ``Proposed 
Mitigation'' and in the Acoustic and Marine Mammal Monitoring Plan. 
Notional monitoring locations are shown in Figures 3-1 and 3-2 of the 
Navy's Plan. Please see that plan, available at http://www.nmfs.noaa.gov/pr/permits/incidental.htm, for full details of the 
required marine mammal monitoring. Based on our requirements, the Plan 
includes the following procedures for pile driving:
     MMOs would be located at the best vantage point(s) in 
order to properly see the entire shutdown zone and as much of the 
disturbance zone as possible.
     During all observation periods, observers will use 
binoculars and the naked eye to search continuously for marine mammals.
     If the shutdown zones are obscured by fog or poor lighting 
conditions, pile driving at that location will not be initiated until 
that zone is visible. Should such conditions arise while impact driving 
is underway, the activity would be halted.
     The shutdown and disturbance zones around the pile will be 
monitored for the presence of marine mammals before, during, and after 
any pile driving or removal activity.
    Individuals implementing the monitoring protocol will assess its 
effectiveness using an adaptive approach. Monitoring biologists will 
use their best professional judgment throughout implementation and seek 
improvements to these methods when deemed appropriate. Any 
modifications to protocol will be coordinated between NMFS and the 
Navy.

Data Collection

    We require that observers use approved data forms. Among other 
pieces of information, the Navy will record detailed information about 
any implementation of shutdowns, including the distance of animals to 
the pile and description of specific actions that ensued and resulting 
behavior of the animal, if any. We require that, at a minimum, the 
following information be collected on the sighting forms:
     Date and time that pile driving begins or ends;
     Construction activities occurring during each observation 
period;
     Weather parameters (e.g., percent cover, visibility);
     Water conditions (e.g., sea state, tide state);
     Species, numbers, and, if possible, sex and age class of 
marine mammals;
     Marine mammal behavior patterns observed, including 
bearing and direction of travel, and if possible, the correlation to 
SPLs;
     Distance from pile driving activities to marine mammals 
and distance from the marine mammals to the observation point;
     Locations of all marine mammal observations; and
     Other human activity in the area.
    In addition, photographs would be taken of any gray whales 
observed. These photographs would be submitted to NMFS' Southwest 
Regional Office for comparison with photo-identification catalogs to 
determine whether the whale is a member of the WNP population.

Reporting

    A draft report would be submitted to NMFS within 45 calendar days 
of the completion of acoustic measurements and marine mammal 
monitoring. The

[[Page 30891]]

report will include marine mammal observations pre-activity, during-
activity, and post-activity during pile driving days, and will also 
provide descriptions of any adverse responses to construction 
activities by marine mammals and a complete description of all 
mitigation shutdowns and the results of those actions. A final report 
would be prepared and submitted within 30 days following resolution of 
comments on the draft report. Required contents of the monitoring 
reports are described in more detail in the Navy's Acoustic and Marine 
Mammal Monitoring Plan.

Estimated Take by Incidental Harassment

    With respect to the activities described here, the MMPA defines 
``harassment'' as: ``any act of pursuit, torment, or annoyance which 
(i) has the potential to injure a marine mammal or marine mammal stock 
in the wild [Level A harassment]; or (ii) has the potential to disturb 
a marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering [Level 
B harassment].''
    All anticipated takes would be by Level B harassment, involving 
temporary changes in behavior. The proposed mitigation and monitoring 
measures are expected to minimize the possibility of injurious or 
lethal takes such that take by Level A harassment, serious injury or 
mortality is considered remote. However, as noted earlier, it is 
unlikely that injurious or lethal takes would occur even in the absence 
of the planned mitigation and monitoring measures.
    If a marine mammal responds to an underwater sound by changing its 
behavior (e.g., through relatively minor changes in locomotion 
direction/speed or vocalization behavior), the response may or may not 
constitute taking at the individual level, and is unlikely to affect 
the stock or the species as a whole. However, if a sound source 
displaces marine mammals from an important feeding or breeding area for 
a prolonged period, impacts on animals or on the stock or species could 
potentially be significant (Lusseau and Bejder, 2007; Weilgart, 2007). 
Given the many uncertainties in predicting the quantity and types of 
impacts of sound on marine mammals, it is common practice to estimate 
how many animals are likely to be present within a particular distance 
of a given activity, or exposed to a particular level of sound. This 
practice potentially overestimates the numbers of marine mammals taken.
    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 (with the exception of California sea 
lions). The occurrence of California sea lions in the project area, 
and, therefore, the likely incidence of exposure of sea lions to sound 
levels above relevant thresholds, will be much reduced due to the 
relocation of the bait barges (i.e., significant California sea lion 
haul-outs). Behavioral disturbances that could result from 
anthropogenic sound associated with the proposed activities are 
expected to affect only a relatively small number of individual marine 
mammals, although those effects could be recurring over the life of the 
project if the same individuals remain in the project vicinity.
    The Navy is requesting authorization for the potential taking of 
small numbers of California sea lions, harbor seals, bottlenose 
dolphins, and gray whales in San Diego Bay that may result from pile 
driving during construction activities associated with the fuel pier 
replacement project described previously in this document. The takes 
requested are expected to have no more than a minor effect on 
individual animals and no effect at the population level for these 
species. Any effects experienced by individual marine mammals are 
anticipated to be limited to short-term disturbance of normal behavior 
or temporary displacement of animals near the source of the sound.

Marine Mammal Densities

    For all species, the best scientific information available was used 
to construct density estimates or estimate local abundance. Although 
information exists for regional offshore surveys for marine mammals, it 
is unlikely that these data would be representative of the fauna that 
may be encountered in San Diego Bay. As a result, the data resulting 
from dedicated line-transect surveys conducted by the Navy from 2007-
12, or from opportunistic observations for more rarely observed 
species, was deemed most appropriate for use in estimating the number 
of incidental harassments that may occur as a result of the specified 
activities (see Figures 3-1 and 3-2 of the Navy's application). Boat 
survey transects established within northern San Diego Bay in 2007 have 
been resurveyed on 16 occasions, 13 of which were during the seasonal 
window for in-water construction and demolition (September-April).

Description of Take Calculation

    The take calculations presented here rely on the best data 
currently available for marine mammal populations in San Diego Bay. The 
formula was developed for calculating take due to pile driving activity 
and applied to each group-specific sound impact threshold. The formula 
is founded on the following assumptions:
     Each species' density is based on the average daily number 
of individuals observed within the project area (defined as the 120-dB 
ZOI for potential behavioral disturbance by vibratory pile driving) 
during Navy marine mammal surveys, corrected for detection probability. 
It is the opinion of the professional biologists who conducted these 
surveys that detectability of animals during these surveys, at slow 
speeds and under calm weather and excellent viewing conditions, 
approached 100%. However, to account for the possibility that some 
parts of the study area may not have been covered due to access 
limitations, and to allow for variation in the accuracy of counts of 
large numbers of animals, a 95% detection rate is assumed.
     ZOIs for underwater sound generating activities at the 
fuel pier location are based on sound emanating from a central point in 
the water column slightly offshore of the existing pier, at the source 
levels specified in Table 5, and rates of transmission loss derived 
from the site-specific model described in Appendix A of the Navy's 
application.
     Pile driving or vibratory extraction is conservatively 
estimated to occur on every day within the scheduled window for that 
component of project construction, as defined in in the project 
description.
     An individual can only be ``taken'' once during each 24-
hour period of activity.
     Although sea lions and harbor seals in the project area 
spend a considerable amount of time above water, when they would not be 
subject to underwater sound, the conservative assumption is made that 
all sea lions within the ZOI are underwater during at least a portion 
of the noise generating activity, and hence exposed to sound at the 
predicted levels. However, all sea lions within each airborne sound ZOI 
are also assumed to be exposed to the airborne sound of each activity.
    The calculation for marine mammal takes is estimated by:

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

Where:

n = density estimate used for each species/

[[Page 30892]]

season
n * ZOI produces an estimate of the abundance of animals that could 
be present in the area for exposure, and is rounded to the nearest 
whole number before multiplying by days of total activity.

    The ZOI impact area is the estimated range of impact to the sound 
criteria. The distances (actual) specified in Table 5 were used to 
calculate ZOI around each pile. The ZOI impact area took into 
consideration the possible affected area of San Diego Bay with 
attenuation due to land shadowing from bends in the shoreline. Because 
of the close proximity of some of the piles to the shore, the ZOIs for 
each threshold are not necessarily spherical and may be truncated.
    While pile driving can occur any day throughout the in-water work 
window, and the analysis is conducted on a per day basis, only a 
fraction of that time is actually spent pile driving. On days when pile 
driving occurs, it could take place for thirty minutes, or up to 
several hours. The Navy assumes that the contractor will drive 
approximately two steel piles per day, and five concrete or fiberglass 
piles per day. For each pile installed, vibratory pile driving is 
expected to be no more than 1-1.5 hours. The impact driving portion of 
the project is anticipated to take approximately thirty minutes per 
pile (for proofing, when necessary). Based on the proposed action, the 
total pile driving time from vibratory pile driving during installation 
would be a maximum of 66 days. Approximately 21 days of demolition work 
might involve methods that could cause disturbance to marine mammals 
are expected.
    The exposure assessment methodology is an estimate of the numbers 
of individuals exposed to the effects of pile driving activities 
exceeding NMFS-established thresholds. Of note in these exposure 
estimates, mitigation methods (i.e., visual monitoring and the use of 
shutdown zones) were not quantified within the assessment and 
successful implementation of mitigation is not reflected in exposure 
estimates. Results from acoustic impact exposure assessments should be 
regarded as conservative estimates.

California Sea Lion

    The Navy Marine Species Density Database (NMSDD) reports estimated 
densities for North and Central San Diego Bay of 5.75/km\2\ for the 
summer and fall periods and 2.51/km\2\ during the winter and spring. 
During Navy surveys of northern San Diego Bay, the maximum number of 
sea lions observed within the study area was 114, with an average 
abundance of 59.92 individuals per survey day; translating to an 
average density of 5.22/km\2\. Adjusting based on 95% detection results 
in an average abundance of 63.07 and density of 5.50/km\2\, which is 
similar to the value reported by Hanser et al. (2012). For California 
sea lions, the most common species in northern San Diego Bay and the 
only species with regular occurrence in the project area, it was 
determined that the density value derived from site-specific surveys 
would be most appropriate for use in estimating potential incidences of 
take.
    In the surveys analyzed for this IHA request, an average of 47.00 
animals were observed on or swimming next to the bait barges. Assuming 
the same proportion of the population continues to spend most of their 
time at the bait barges when they are relocated, there would be an 
average of 12.92 individuals within the ZOI (1.12/km\2\). Assuming 95% 
detection results in an estimated average abundance of 13.60 and 
density of 1.18/km\2\ in the ZOI without the bait barges' influence as 
a sea lion aggregator within the project area. With the relocation of 
the bait barges, no haul-outs are available for California sea lions 
within the airborne ZOI. We acknowledge that California sea lions may 
experience airborne acoustic harassment when in the water within the 
airborne ZOI but with their heads above water. However, these animals 
are considered harassed by underwater sound.

Harbor Seal

    As discussed previously, the occurrence of harbor seals in the ZOI 
appears to be limited. Small numbers of individuals are known to haul 
out south of Ballast Point, but these have not been observed entering 
or transiting the project area and are believed to move from this 
location to haul-outs further north at La Jolla. Accordingly, harbor 
seal presence in the project area is assessed on the basis of the only 
observational data available, the opportunistic observation of several 
individuals occurring in the vicinity of Pier 122 repeatedly for a 
period of about a month. We therefore assume that as many as three 
harbor seals could be incidentally harassed on a daily basis for as 
much as one month. In addition, because the Pier 122 location is 
approximately 250 m from the fuel pier, these individuals we assume 
that these individuals could be either in the water or hauled out each 
day and therefore conservatively consider them to be exposed to both 
underwater and airborne sound on each day.

Gray Whale

    Similar to the harbor seal, observational data for gray whales is 
limited and their occurrence in the project area infrequent and 
unpredictable. On the basis of limited information, we assume here that 
15 exposures of gray whales to sound that could result in harassment 
might occur. This could result from as many as 15 individuals 
transiting near the mouth of the Bay, or from one individual entering 
the Bay and lingering in the project area for 15 days. We limit the 
time period to 15 days because, although both of these scenarios are 
unlikely, they would only possibly occur in March. Most sightings of 
gray whales near or within the Bay have been outside of the in-water 
work window.

Bottlenose Dolphin

    Coastal bottlenose dolphins can occur at any time of year in San 
Diego Bay, and with California sea lions are the only species observed 
during site-specific marine mammal surveys conducted by the Navy. 
Numbers sighted have been highly variable, ranging from zero (6 out of 
13 surveys) to 40 individuals. Unidentified dolphins recorded in the 
surveys are assumed to have been coastal bottlenose dolphins. Given the 
sporadic nature of bottlenose dolphin sightings and their high 
variability in terms of numbers and locations, the regional density 
estimate of 0.36/km\2\ developed for the NMSDD (Hanser et al., 2012) 
was considered a more reliable indicator of the number of bottlenose 
dolphins that may be present and is used here to estimate the potential 
number of incidences of take.
    Steel pile installation involves a combination of vibratory and 
impact hammering. Both are assumed to occur on the same day and, 
therefore, the estimated number of animals taken is given by the 
maximum of either type of exposure. Given that the vibratory (120 dB 
rms) ZOI is larger, all animals considered behaviorally harassed by 
impact pile driving are also considered to potentially be harassed by 
vibratory pile driving, whereas animals outside of the ZOI for impact 
hammering but within the ZOI for vibratory hammering would only be 
harassed by the latter. For example, for California sea lions the 
estimate for vibratory pile driving is 700 and the estimate for impact 
pile driving is 500. Because both events occur on the same day and the 
vibratory harassment zone subsumes the impact harassment zone, the 
estimate for vibratory pile driving necessarily includes the 500 
incidents of harassment estimated for impact pile driving alone. To 
provide a

[[Page 30893]]

more conservative estimate of total harassments, demolition use of 
vibratory extraction is assumed not to overlap the driving of steel 
piles for the new pier. Thus, the 294 incidences of harassment for 
California sea lions resulting from pile removal would add to the 700 
estimated for pile installation (500 resulting from either vibratory or 
impact installation and 200 resulting from vibratory installation 
alone) for a total estimate of 994 incidences of harassment.

                         Table 8--Number of Potential Incidental Takes of Marine Mammals Within Various Acoustic Threshold Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Underwater                                        Airborne
                                                                     ----------------------------                            --------------
                                                                                     Disturbance    Vibratory     Vibratory                     Total
                                                           Density       Impact      threshold,      injury      disturbance     Impact       proposed
                        Species                          (/     injury       combined      threshold     threshold    disturbance   authorized
                                                           km \2\)      threshold      impact/    (180/190 dB)    (120 dB)      threshold       takes
                                                                      (180/190 dB)    vibratory                                (90/100 dB)
                                                                                    (160 dB) \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion...................................          1.18             0           500             0           494             0           994
Harbor seal \2\.......................................           n/a             0            90             0             0            90           180
Gray whale \2\........................................           n/a             0            15             0             0           n/a            15
Bottlenose dolphin....................................          0.36             0           144             0           163           n/a           307
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The 160-dB acoustic harassment zone associated with impact pile driving would always be subsumed by the 120-dB harassment zone produced by vibratory
  driving. Therefore, total takes estimated for impact driving alone could occur as a result of either impact or vibratory driving.
\2\ Because there is no density estimate available for harbor seals or gray whales, we cannot estimate takes separately for vibratory and impact pile
  driving. We simply assume here that these animals could be present within the project area for 30 (3 harbor seals) or 15 days (1 gray whale),
  respectively, and that they could be taken by impact or vibratory driving or vibratory removal. We also assume that mitigation measures would be
  effective in preventing Level A harassment for these species and believe a zero value for Level A harassments to be reasonable.

    Potential takes could occur if individuals of these species move 
through the area on foraging trips when pile driving is occurring. 
Individuals that are taken could exhibit behavioral changes such as 
increased swimming speeds, increased surfacing time, or decreased 
foraging. Most likely, individuals may move away from the sound source 
and be temporarily displaced from the areas of pile driving. Potential 
takes by disturbance would likely have a negligible short-term effect 
on individuals and not result in population-level impacts. 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, 
we consider a variety of factors, including but not limited to: (1) The 
number of anticipated mortalities; (2) the number and nature of 
anticipated injuries; (3) the number, nature, intensity, and duration 
of Level B harassment; and (4) the context in which the take occurs.
    Pile driving activities associated with the pier replacement 
project, as outlined previously, have the potential to disturb or 
displace marine mammals. Specifically, the proposed activities may 
result in take, in the form of Level B harassment (behavioral 
disturbance) only, from airborne or underwater sounds generated from 
pile driving. No mortality, serious injury, or Level A harassment is 
anticipated given the methods of installation and measures designed to 
minimize the possibility of injury to marine mammals and Level B 
harassment would be reduced to the level of least practicable adverse 
impact. Specifically, vibratory hammers, which do not have significant 
potential to cause injury to marine mammals due to the relatively low 
source levels (less than 190 dB), would be the primary method of 
installation. Also, pile driving would either not start or be halted if 
marine mammals approach the shutdown zone (described previously in this 
document). The pile driving activities analyzed here are similar to 
other similar construction activities, including recent projects 
conducted by the Navy in the Hood Canal as well as substantial work 
conducted in San Francisco Bay by the California Department of 
Transportation, which have taken place with no reported injuries or 
mortality to marine mammals.
    The proposed numbers of authorized take for California sea lions, 
harbor seals, and gray whales would be considered small relative to the 
relevant stocks or populations (each less than one percent) even if 
each estimated taking occurred to a new individual--an extremely 
unlikely scenario. For pinnipeds, no rookeries are present in the 
project area, there are no haul-outs other than those provided 
opportunistically by man-made objects, and the project area is not 
known to provide foraging habitat of any special importance.
    The proposed numbers of authorized take for bottlenose dolphins are 
higher relative to the total stock abundance estimate and would not 
represent small numbers if a significant portion of the take was for a 
new individual. However, these numbers represent the estimated 
incidences of take, not the number of individuals taken. That is, it is 
likely that a relatively small subset of California coastal bottlenose 
dolphins would be harassed by project activities. California coastal 
bottlenose dolphins range from San Francisco Bay to San Diego (and 
south into Mexico) and the specified activity would be stationary 
within an enclosed Bay that is not recognized as an area of any special 
significance for coastal bottlenose dolphins (and is therefore not an 
area of dolphin aggregation, as evident in Navy observational records). 
We therefore believe that the estimated numbers of takes, were they to 
occur, likely represent repeated exposures of a much smaller number of 
bottlenose dolphins and that, based on the limited region of exposure 
in comparison with the known distribution of the coastal bottlenose 
dolphin, these estimated incidences of take represent small numbers of 
bottlenose dolphins.
    Repeated exposures of individuals to levels of sound that may cause 
Level B harassment are unlikely to result in hearing impairment or to 
significantly disrupt foraging behavior. Thus, even repeated Level B 
harassment of some small subset of the overall stock is

[[Page 30894]]

unlikely to result in any significant realized decrease in viability 
for California coastal bottlenose dolphins, and thus would not result 
in any adverse impact to the stock as a whole. The potential for 
multiple exposures of a small portion of the overall stock to levels 
associated with Level B harassment in this area is expected to have a 
negligible impact on the stock.
    We have preliminarily determined that the impact of the first phase 
of the previously described wharf construction project, to be conducted 
under this proposed one-year IHA, may result, at worst, in a temporary 
modification in behavior (Level B harassment) of small numbers of 
marine mammals. No injuries, serious injuries, or mortalities are 
anticipated as a result of the specified activity, and none are 
proposed to be authorized. Additionally, animals in the area are not 
expected to incur hearing impairment (i.e., TTS or PTS) or non-auditory 
physiological effects. For pinnipeds, the absence of any major 
rookeries and only a few isolated and opportunistic haul-out areas near 
or adjacent to the project site means that potential takes by 
disturbance would have an insignificant short-term effect on 
individuals and would not result in population-level impacts. 
Similarly, for cetacean species the absence of any known regular 
occurrence adjacent to the project site means that potential takes by 
disturbance would have an insignificant short-term effect on 
individuals and would not result in population-level impacts. Due to 
the nature, degree, and context of behavioral harassment anticipated, 
the activity is not expected to impact rates of recruitment or 
survival.
    For reasons stated previously in this document, the negligible 
impact determination is also supported by the likelihood that, given 
sufficient ``notice'' through mitigation measures including soft start, 
marine mammals are expected to move away from a sound source that is 
annoying prior to its becoming potentially injurious, and the 
likelihood that marine mammal detection ability by trained observers is 
high under the environmental conditions described for San Diego Bay, 
enabling the implementation of shutdowns to avoid injury, serious 
injury, or mortality. As a result, no take by injury, serious injury or 
death is anticipated, and the potential for temporary or permanent 
hearing impairment is very low and would be avoided through the 
incorporation of the proposed mitigation measures.
    While the number of marine mammals potentially incidentally 
harassed would depend on the distribution and abundance of marine 
mammals in the vicinity of the survey activity, the number of potential 
harassment takings is estimated to be small, and has been mitigated to 
the lowest level practicable through incorporation of the proposed 
mitigation and monitoring measures mentioned previously in this 
document. This activity is expected to result in a negligible impact on 
the affected species or stocks. No species for which take authorization 
is requested are either ESA-listed or considered depleted under the 
MMPA.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the mitigation and monitoring 
measures, we preliminarily find that the first year of construction 
associated with the proposed pier replacement project would result in 
the incidental take of small numbers of marine mammal, by Level B 
harassment only, and that the total taking from the activity would have 
a negligible impact on the affected species or stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    There are no relevant subsistence uses of marine mammals implicated 
by this action.

Endangered Species Act (ESA)

    The Navy initiated informal consultation under section 7 of the ESA 
with NMFS Southwest Regional Office on March 5, 2013. NMFS concluded on 
May 16, 2013, that the proposed action may affect, but is not likely to 
adversely affect, WNP gray whales. The Navy has not requested 
authorization of the incidental take of WNP gray whales and no such 
authorization is proposed, and there are no other ESA-listed marine 
mammals found in the action area. Therefore, no consultation under the 
ESA is required.

National Environmental Policy Act (NEPA)

    In September 2012, the Navy prepared a Draft Environmental 
Assessment (Naval Base Point Loma Fuel Pier Replacement and Dredging 
(P-151/DESC1306) Environmental Assessment) in accordance with the 
National Environmental Policy Act (NEPA) and the regulations published 
by the Council on Environmental Quality. We have posted it on the NMFS 
Web site (see ADDRESSES) concurrently with the publication of this 
proposed IHA. NMFS will independently evaluate the EA and determine 
whether or not to adopt it. We may prepare a separate NEPA analysis and 
incorporate relevant portions of the Navy's EA by reference. 
Information in the Navy's application, EA and this notice collectively 
provide the environmental information related to proposed issuance of 
the IHA for public review and comment. We will review all comments 
submitted in response to this notice as we complete the NEPA process, 
including a decision of whether to sign a Finding of No Significant 
Impact (FONSI), prior to a final decision on the IHA request.

Proposed Authorization

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

    Dated: May 17, 2013.
Helen M. Golde,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2013-12251 Filed 5-22-13; 8:45 am]
BILLING CODE 3510-22-P