[Federal Register Volume 78, Number 71 (Friday, April 12, 2013)]
[Proposed Rules]
[Pages 22096-22124]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-08390]



[[Page 22095]]

Vol. 78

Friday,

No. 71

April 12, 2013

Part III





Department of Commerce





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National Oceanic and Atmospheric Administration





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50 CFR Part 218





Taking and Importing Marine Mammals; Taking Marine Mammals Incidental 
to Replacement of the Elliott Bay Seawall in Seattle, Washington; 
Proposed Rule

  Federal Register / Vol. 78 , No. 71 / Friday, April 12, 2013 / 
Proposed Rules  

[[Page 22096]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[Docket No. 130325286-3286-01]
RIN 0648-BC69


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to Replacement of the Elliott Bay Seawall in Seattle, 
Washington

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

ACTION: Proposed rule; request for comments.

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SUMMARY: NMFS has received a request from the Seattle Department of 
Transportation (SDOT), on behalf of the City of Seattle (City), for 
authorization to take marine mammals incidental to construction 
associated with the replacement of the Elliott Bay Seawall in Seattle, 
Washington, for the period September 2013 to September 2018. Pursuant 
to the Marine Mammal Protection Act (MMPA), NMFS is proposing 
regulations to govern that take and requests information, suggestions, 
and comments on these proposed regulations.

DATES: Comments and information must be received no later than May 13, 
2013.

ADDRESSES: You may submit comments on this document, identified by 
0648-BC69, by any of the following methods:
     Electronic Submission: Submit all electronic public 
comments via the Federal e-Rulemaking Portal www.regulations.gov. To 
submit comments via the e-Rulemaking Portal, first click the Submit a 
Comment icon, then enter 0648-BC69 in the keyword search. Locate the 
document you wish to comment on from the resulting list and click on 
the Submit a Comment icon on the right of that line.
     Hand delivery or mailing of comments via paper or disc 
should be addressed to P. Michael Payne, Chief, Permits and 
Conservation Division, Office of Protected Resources, National Marine 
Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910.
    Comments regarding any aspect of the collection of information 
requirement contained in this proposed rule should be sent to NMFS via 
one of the means provided here and to the Office of Information and 
Regulatory Affairs, NEOB-10202, Office of Management and Budget, Attn: 
Desk Office, Washington, DC 20503, [email protected].
    Instructions: Comments must be submitted by one of the above 
methods to ensure that the comments are received, documented, and 
considered by NMFS. Comments sent by any other method, to any other 
address or individual, or received after the end of the comment period, 
may not be considered. All comments received are a part of the public 
record and will generally be posted for public viewing on 
www.regulations.gov without change. All personal identifying 
information (e.g., name, address) submitted voluntarily by the sender 
will be publicly accessible. Do not submit confidential business 
information, or otherwise sensitive or protected information. NMFS will 
accept anonymous comments (enter N/A in the required fields if you wish 
to remain anonymous). Attachments to electronic comments will be 
accepted in Microsoft Word, Excel, or Adobe PDF file formats only.

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

SUPPLEMENTARY INFORMATION: 

Availability

    A copy of SDOT's application, and other supplemental documents, may 
be obtained by visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications. Documents cited in this notice may 
also be viewed, by appointment, during regular business hours, at the 
aforementioned address.

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.''
    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

    On September 17, 2012, NMFS received a complete application from 
SDOT requesting authorization for the take of nine marine mammal 
species incidental to replacement of the Elliott Bay Seawall in 
Seattle, Washington, over the course of 5 years. The purpose of the 
proposed project is to reduce the risks of coastal storm and seismic 
damage and to protect public safety, critical infrastructure, and 
associated economic activities in the area. Additionally, the project 
would improve the degraded ecosystem functions and processes of the 
Elliott Bay nearshore around the existing seawall. Noise produced 
during pile installation and removal activities has the potential to 
take marine mammals. SDOT requested, and NMFS is proposing, 
authorization to take nine marine mammal species by Level B harassment 
only: Pacific harbor seal (Phoca vitulina), California sea lion 
(Zalophus californianus), Steller sea lion (Eumetopias jubatus), harbor 
porpoise (Phocoena phocoena), Dall's porpoise (Phocoenoides dalli), 
southern resident and transient killer whales (Orcinus orca), humpback 
whale (Megaptera novaengliae), and gray whale (Eschrichtius jubatus). 
Injury or mortality is unlikely during the proposed project, and take 
by Level A harassment (including injury) or mortality is not requested 
nor proposed for authorization.

Description of the Specified Activity

    SDOT proposes to replace the Elliott Bay Seawall from South 
Washington Street to Broad Street, along the Seattle waterfront 
abutting Elliott Bay in King County, Washington. The purpose of the 
project is to reduce the risks of coastal storm and seismic damages and 
to

[[Page 22097]]

protect public safety, critical infrastructure, and associated economic 
activities along Seattle's central waterfront. Additionally, the 
project would improve nearshore ecosystem functions and processes in 
the vicinity of the existing seawall. The proposed project would be 
constructed in two phases: Phase 1 would extend for about 3,600 linear 
feet (ft) (1 kilometer (km)) from South Washington Street to Virginia 
Street, and Phase 2 would extend for about 3,500 linear ft (1 km) from 
Virginia to Broad Streets.
    The new seawall would be constructed landward of the existing 
seawall face and result in a net setback of the wall from its existing 
location. The majority of seawall construction would occur behind a 
temporary steel sheet pile containment wall that would be placed 
waterward of the existing seawall complex and extend the full length of 
the construction work area during each construction season. The seawall 
structure would consist of a soil improvement structure that would 
stabilize the soils behind the existing seawall and may include anchors 
or tie-backs that extend down to non-liquefiable soil for seismic 
stability. A four-lane primary arterial that runs along the entire 
length of the seawall would need to be relocated during seawall 
construction. A stormwater treatment system would be installed to treat 
stormwater runoff from the project area using basic treatment 
technology to meet City code. Public amenities resulting from the 
project would include replaced railings, restoration of the Washington 
Street boat landing, riparian planters, street plantings, and 
reconstructed sidewalks.
    Construction activities that may result in the take of marine 
mammals include in-water vibratory and impact pile installation and 
removal. An APE 200 or equivalent-type of vibratory hammer would be 
used, with no more than an APE 400 model required for a worst-case 
scenario. A Delmag D46-32 or equivalent-type of impact hammer would be 
used, with no more than a Delmag D62-22 required for a worst-case 
scenario. A total of 1,930 piles would be installed over a 5-year 
period, and 1,740 of those piles would also be removed (leaving 190 
permanent piles). In addition, 80 existing piles would be removed over 
a 5-year period. All proposed in-water pile installation and removal is 
summarized in Tables 1 through 3 below. To account for potential mid-
project changes in pile numbers, SDOT included a 10 percent contingency 
in their estimates for installation and removal. These contingency 
numbers are used in all calculations and assessments in this document. 
Roughly the same number and distribution of in-water steel sheet piles 
and permanent piles is expected for each year of the project. Piles 
installed in upland areas are not expected to result in the take of 
marine mammals because sound levels would not reach NMFS threshold 
criteria underwater and there are no pinniped haul-outs in the 
immediate area. Upland pile installation is not mentioned further.
    Prior to excavation and demolition of the existing seawall, a 
temporary containment wall constructed of steel sheet piles would be 
installed in each construction segment (Table 1). The temporary 
containment wall would be installed by vibratory driving and would be 
located in the water about 5 ft (1.5 m) waterward of the existing 
seawall. It would remain in place throughout the duration of 
construction. After construction, the temporary containment wall would 
be removed with vibratory equipment. In the rare case where steel sheet 
piles would be load bearing, an impact hammer may be required to 
``proof'' or set the piles. The temporary containment wall would serve 
to prevent adverse effects on nearshore marine habitat from the release 
of turbidity and contaminants associated with seawall excavation and 
demolition.

                          Table 1--Temporary Containment Wall Installation and Removal
                                            [Steel sheet piles only]
----------------------------------------------------------------------------------------------------------------
                                   Pile pairs \1\
       Construction phase         (10% contingency  Maximum  duration    Maximum hours     Installation/ removal
                                     included)            (days)            per day               method
----------------------------------------------------------------------------------------------------------------
                                                  Installation
----------------------------------------------------------------------------------------------------------------
Phase 1 (Years 1-3)............              1,023                 60                 12  vibratory.
Estimated number of piles that                 205              \3\ 4                 10  impact.
 would require proofing \2\.
Phase II (Years 4-5)...........                717                 40                 12  vibratory.
Estimated number of piles that                 143              \3\ 4                 10  impact.
 would require proofing \2\.
----------------------------------------------------------------------------------------------------------------
                                                     Removal
----------------------------------------------------------------------------------------------------------------
Phase I........................              1,023                 25                 12  vibratory.
Phase II.......................                717                 15                 12  vibratory.
                                ---------------------------------------------------------
    Total Installed/Removed....              1,740
----------------------------------------------------------------------------------------------------------------
\1\ Steel sheet pile pairs only (48 inches wide).
\2\ Number equals 20 percent of estimated number of piles installed per phase.
\3\ Total estimated installation time is 8 hours of actual impact driving.
\4\ Total estimated installation time is 12 hours of actual impact driving.

    Existing creosote-treated timber piles and concrete piles located 
waterward of the existing seawall face that would interfere with 
construction would be removed using a vibratory extraction method 
(Table 2). Timber pilings that break during extraction would be cut off 
2 ft (0.6 m) below the mudline.

[[Page 22098]]



                                                             Table 2--Existing Pile Removal
                                                            [Timber and concrete piles only]
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                                                                                                   Maximum
        Construction phase            Piles \1\          Pile type         Justification for      duration      Maximum hours       Removal  method
                                                                                removal            (days)          per day
--------------------------------------------------------------------------------------------------------------------------------------------------------
Phase 1 (Excluding Washington                  20  Creosote-treated      Currently not used;                2              12  vibratory.
 Street Boat Landing).                              timber\2\.            from previous uses
                                                                          along wall.
Phase I (Washington Street Boat                 8  Creosote-treated      Support existing                   1              12  vibratory.
 Landing Only).                                     timber\2\.            pier structure.
Phase II.........................              49  Creosote-treated      Currently not used;                2              12  vibratory.
                                                    timber\2\.            from previous uses
                                                                          along wall.
Phase II.........................               3  Concrete\3\.........  Currently not used;                1              12  vibratory.
                                                                          from previous uses
                                                                          along wall.
                                  ----------------                                            ----------------
    Total Removed................              80                                                           6
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number includes 10 percent contingency.
\2\ Assumed to be 14-in diameter.
\3\ Assumed to be 18-in diameter.

    About 190 permanent concrete piles would be installed on either 
side of the temporary sheet pile containment wall using impact pile 
installation (Table 3). All in-water permanent piles are assumed to be 
16.5-in-diameter (42-cm) precast concrete octagonal piles. The 
temporary sheet pile containment wall may serve as an attenuation 
device during impact pile installation to reduce sound levels by up to 
10 decibels (dB). The concrete pilings installed landward of the 
temporary containment wall are intended to provide permanent structural 
support for cantilevered sidewalks and pier areas with high vehicle 
traffic. The remaining pilings installed waterward of the temporary 
containment wall would support the replacement of the Washington Street 
Boat Landing.

                                      Table 3--Permanent Pile Installation
                        [16.5-in-diameter (42-cm) precast concrete octagonal piles only]
----------------------------------------------------------------------------------------------------------------
                                                Justification       Maximum
      Construction phase            Piles            for           duration      Maximum hours    Installation
                                                 installation       (days)          per day          method
----------------------------------------------------------------------------------------------------------------
Phase I (Excluding Washington              92  To support                   11              10  Impact.
 Street Boat Landing).                          sidewalk,
                                                viewing areas,
                                                and vehicular
                                                traffic access.
Phase I (Washington Street                 15  To support new                2              10  Impact.
 Boat Landing Only).                            pier structure.
Phase II.....................              83  To support                   10              10  Impact.
                                                sidewalk and
                                                viewing areas.
                              ----------------                 ----------------
    Total Installed..........             190                               23
----------------------------------------------------------------------------------------------------------------

Dates and Duration of Specified Activity

    Seawall construction is expected to occur in two phases: Phase 1, 
which includes the area of the Central Seawall, and Phase 2, which 
includes the area of the North Seawall (Table 4). Phase 1 includes 
three construction segments, and Phase 2 includes two construction 
segments; each segment represents 1 to 2 years of construction. 
Construction is scheduled to begin with Phase I work in fall 2013. The 
three segments of Phase 1 would be constructed over three construction 
seasons with two summer shutdown periods from Memorial Day weekend 
through Labor Day weekend to accommodate the primary tourist and 
business season. Phase 2 construction is expected to begin following 
completion of Phase 1 and would occur over two 2-year construction 
seasons with a summer shutdown period each year. SDOT's Letter of 
Authorization (LOA) request covers the construction period from 2013 to 
2018, from the start of Phase 1, Segment 1 to the end of Phase 2, 
Segment 1. A request for another MMPA authorization may be submitted 
for any further construction.

                                                     Table 4--Proposed Project Construction Schedule
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Phase                            Segment                                             Duration
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 (Central Seawall)...........................                   I  Year 1 (Fall 2013-Spring 2014).
                                                                II  Year 2 (Fall 2014-Spring 2015).
                                                               III  Year 3 (Fall 2015-Spring 2016).
2 (North Seawall).............................                   I  Years 4 and 5 (Fall 2016-Spring 2018).
                                                                II  Years 6 and 7 (Fall 2018-Spring 2020).*
--------------------------------------------------------------------------------------------------------------------------------------------------------
*Note: Years 6 and 7 would not be covered under this LOA request because the MMPA limits incidental take authorizations to 5-year periods.


[[Page 22099]]

Specified Geographical Region

    The Elliott Bay Seawall runs along the downtown Seattle waterfront 
in King County, Washington. SDOT's proposed project would occur between 
South Washington Street and Broad Street, which abut Elliott Bay, a 21-
square kilometer (km\2\) urban embayment in central Puget Sound. The 
inner bay receives fresh water from the Duwamish River and most of the 
stormwater runoff from 67 km\2\ of highly developed land in 
metropolitan Seattle. This is an important industrial region and home 
to the Port of Seattle, which ranked as the nation's sixth busiest U.S. 
seaport in 2010.
    The region of the specified activity (or ``area of potential 
effects,'' as described in SDOT's application) is the area in which 
elevated sound levels from pile-related activities could result in the 
take of marine mammals. This area includes the proposed construction 
zone, Elliott Bay, and a portion of Puget Sound. The construction zone 
extends for about 7,100 linear ft (2,165 m) along the Seattle shoreline 
and is mostly concentrated in upland areas. The area of in-water pile 
installation and removal activities would be restricted to the length 
of the seawall and waterward to within 15 ft (4.6 m) of the seawall 
face, and to depths less than 30 feet (9.1 m). SDOT calculated 
unattenuated and unobstructed vibratory pile installation (or removal) 
to propagate up to 2.5 miles (4 km) from the sound source with high 
enough sound levels to meet NMFS' acoustic threshold criteria for 
marine mammal harassment (see Sound Thresholds section below). SDOT 
expects that pile-related construction noise could extend throughout 
the nearshore and open water environments to just west of Alki Point 
and a limited distance into the East Waterway of the Lower Duwamish 
River (a highly industrialized waterway).

Brief Background on Sound

    An understanding of the basic properties of underwater sound is 
necessary to comprehend many of the concepts and analyses presented in 
this document. A summary is included below.
    Sound is a wave of pressure variations propagating through a medium 
(e.g., water). Pressure variations are created by compressing and 
relaxing the medium. Sound measurements can be expressed in two forms: 
intensity and pressure. Acoustic intensity is the average rate of 
energy transmitted through a unit area in a specified direction and is 
expressed in watts per square meter (W/m\2\). Acoustic intensity is 
rarely measured directly, but rather from ratios of pressures; the 
standard reference pressure for underwater sound is 1 microPascal 
([micro]Pa); for airborne sound, the standard reference pressure is 20 
[micro]Pa (Richardson et al., 1995).
    Acousticians have adopted a logarithmic scale for sound 
intensities, which is denoted in decibels (dB). Decibel measurements 
represent the ratio between a measured pressure value and a reference 
pressure value (in this case 1 [micro]Pa or, for airborne sound, 20 
[micro]Pa). The logarithmic nature of the scale means that each 10-dB 
increase is a ten-fold increase in acoustic power (and a 20-dB increase 
is then a 100-fold increase in power; and a 30-dB increase is a 1,000-
fold increase in power). A ten-fold increase in acoustic power does not 
mean that the sound is perceived as being ten times louder, however. 
Humans perceive a 10-dB increase in sound level as a doubling of 
loudness, and a 10-dB decrease in sound level as a halving of loudness. 
The term ``sound pressure level'' implies a decibel measure and a 
reference pressure that is used as the denominator of the ratio. 
Throughout this document, NMFS uses 1 microPascal (denoted re: 
1[micro]Pa) as a standard reference pressure unless noted otherwise.
    It is important to note that decibel values underwater and decibel 
values in air are not the same (different reference pressures and 
densities/sound speeds between media) and should not be directly 
compared. Because of the different densities of air and water and the 
different decibel standards (i.e., reference pressures) in air and 
water, a sound with the same level in air and in water would be 
approximately 62 dB lower in air. Thus, a sound that measures 160 dB 
(re 1 [micro]Pa) underwater would have the same approximate effective 
level as a sound that is 98 dB (re 20 [micro]Pa) in air.
    Sound frequency is measured in cycles per second, or Hertz 
(abbreviated Hz), and is analogous to musical pitch; high-pitched 
sounds contain high frequencies and low-pitched sounds contain low 
frequencies. Natural sounds in the ocean span a huge range of 
frequencies: from earthquake noise at 5 Hz to harbor porpoise clicks at 
150,000 Hz (150 kHz). These sounds are so low or so high in pitch that 
humans cannot even hear them; acousticians call these infrasonic 
(typically below 20 Hz) and ultrasonic (typically above 20,000 Hz) 
sounds, respectively. A single sound may be made up of many different 
frequencies together. Sounds made up of only a small range of 
frequencies are called ``narrowband'', and sounds with a broad range of 
frequencies are called ``broadband''; explosives are an example of a 
broadband sound source and active tactical sonars are an example of a 
narrowband sound source.
    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 behavioral 
protocols or auditory evoked potential (AEP) 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. Further, the frequency 
range in which each group's hearing is estimated as being most 
sensitive is represented in the flat part of the M-weighting functions 
(which are derived from the audiograms described above; see Figure 1 in 
Southall et al., 2007) developed for each broad group. The functional 
groups and the associated frequencies are indicated below (though, 
again, 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--functional hearing is estimated 
to occur between approximately 7 Hz and 30 kHz;
     Mid-frequency cetaceans--functional hearing is estimated 
to occur between approximately 150 Hz and 160 kHz;
     High-frequency cetaceans--functional hearing is estimated 
to occur between approximately 200 Hz and 180 kHz;
     Pinnipeds in water--functional hearing is estimated to 
occur between approximately 75 Hz and 75 kHz.
    The estimated hearing range for low-frequency cetaceans has been 
extended slightly from previous analyses (from 22 to 30 kHz). This 
decision is based on data from Watkins et al. (1986) for numerous 
mysticete species, Au et al. (2006) for humpback whales, an abstract 
from Frankel (2005) and paper from Lucifredi and Stein (2007) on gray 
whales, and an unpublished report (Ketten and Mountain, 2009) and 
abstract (Tubelli et al., 2012) for minke whales. As more data from 
more species and/or individuals become available, these estimated 
hearing ranges may require modification.
    When sound travels (propagates) from its source, its loudness 
decreases as the distance traveled by the sound

[[Page 22100]]

increases. Thus, the loudness of a sound at its source is higher than 
the loudness of that same sound a kilometer away. Acousticians often 
refer to the loudness of a sound at its source (typically referenced to 
one meter from the source) as the source level and the loudness of 
sound elsewhere as the received level (i.e., typically the receiver). 
For example, a humpback whale 3 km from a device that has a source 
level of 230 dB may only be exposed to sound that is 160 dB loud, 
depending on how the sound travels through water (e.g., spherical 
spreading [3 dB reduction with doubling of distance] was used in this 
example). As a result, it is important to understand the difference 
between source levels and received levels when discussing the loudness 
of sound in the ocean or its impacts on the marine environment.
    As sound travels from a source, its propagation in water is 
influenced by various physical characteristics, including water 
temperature, depth, salinity, and surface and bottom properties that 
cause refraction, reflection, absorption, and scattering of sound 
waves. Oceans are not homogeneous and the contribution of each of these 
individual factors is extremely complex and interrelated. The physical 
characteristics that determine the sound's speed through the water will 
change with depth, season, geographic location, and with time of day 
(as a result, in actual active sonar operations, crews will measure 
oceanic conditions, such as sea water temperature and depth, to 
calibrate models that determine the path the sonar signal will take as 
it travels through the ocean and how strong the sound signal will be at 
a given range along a particular transmission path). As sound travels 
through the ocean, the intensity associated with the wavefront 
diminishes, or attenuates. This decrease in intensity is referred to as 
propagation loss, also commonly called transmission loss.

Metrics Used in This Document

    This section includes a brief explanation of the two sound 
measurements (sound pressure level (SPL) and sound exposure level 
(SEL)) frequently used to describe sound levels in the discussions of 
acoustic effects in this document.
    Sound pressure level (SPL)--Sound pressure is the sound force per 
unit area, and is usually measured in micropascals ([micro]Pa), where 1 
Pa is the pressure resulting from a force of one newton exerted over an 
area of one square meter. SPL is expressed as the ratio of a measured 
sound pressure and a reference level.

SPL (in dB) = 20 log (pressure/reference pressure)

    The commonly used reference pressure level in underwater acoustics 
is 1 [micro]Pa, and the units for SPLs are dB re: 1 [micro]Pa. SPL is 
an instantaneous pressure measurement and can be expressed as the peak, 
the peak-peak, or the root mean square (rms). Root mean square 
pressure, which is the square root of the arithmetic average of the 
squared instantaneous pressure values, is typically used in discussions 
of the effects of sounds on vertebrates and all references to SPL in 
this document refer to the root mean square. SPL does not take the 
duration of exposure into account.
    Sound exposure level (SEL)--SEL is an energy metric that integrates 
the squared instantaneous sound pressure over a stated time interval. 
The units for SEL are dB re: 1 [micro]Pa\2\-s. Below is a simplified 
formula for SEL.

SEL = SPL + 10log(duration in seconds)

    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). Sound 
generated by impact pile driving is highly variable, based on site-
specific conditions such as substrate, water depth, and current. Sound 
levels may also vary based on the size of the pile, the type of pile, 
and the energy of the hammer.
    Vibratory hammers install piles by vibrating them and allowing the 
weight of the hammer to push them into the sediment. Vibratory hammers 
produce much less sound than impact hammers. Peak SPLs may be 180 dB or 
greater, but are generally 10 to 20 dB lower than SPLs generated during 
impact pile driving of the same-sized pile (Caltrans, 2009). Rise time 
is slower, reducing the probability and severity of injury (USFWS, 
2009), and sound energy is distributed over a greater amount of time 
(Nedwell and Edwards, 2002; Carlson et al., 2001). However, vibratory 
hammers cannot be used in all circumstances. In some substrates, the 
capacity of a vibratory hammer may be insufficient to drive the pile to 
load-bearing capacity or depth (Caltrans, 2009). Additionally, some 
vibrated piles must be `proofed' (i.e., struck with an impact hammer) 
for several seconds to several minutes in order to verify the load-
bearing capacity of the pile (WSDOT, 2008).
    Impact and vibratory pile driving are the primary in-water 
construction activities associated with the project. The sounds 
produced by these activities fall into one of two sound types: pulsed 
and non-pulsed (defined in next paragraph). Impact pile driving 
produces pulsed sounds, while vibratory pile driving produces non-
pulsed sounds. The distinction between these two general sound types is 
important because they have differing potential to cause physical 
effects, particularly with regard to hearing (e.g., Ward, 1997 in 
Southall et al., 2007). Southall et al. (2007) provides an in-depth 
discussion of these concepts and a summary is provided here.
    Pulsed sounds (e.g., explosions, gunshots, sonic booms, seismic 
pile driving pulses, and impact pile driving) are brief, broadband, 
atonal transients (ANSI, 1986; Harris, 1998) and occur either as 
isolated events or repeated in some succession. Pulsed sounds are all 
characterized by a relatively rapid rise from ambient pressure to a 
maximal pressure value followed by a decay period that may include a 
period of diminishing, oscillating maximal and minimal pressures. 
Pulsed sounds generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds (which may be intermittent or continuous) 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.

Sound Thresholds

    Since 1997, NMFS has used generic sound exposure thresholds to 
determine when an activity in the ocean that produces sound might 
result in impacts to a marine mammal such that a take by harassment or 
injury might occur (NMFS, 2005b). To date, no studies have been 
conducted that examine impacts to marine mammals from pile driving 
sounds from which empirical sound thresholds have been established. 
Current NMFS practice regarding exposure of marine mammals to high 
levels of 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

[[Page 22101]]

(Level B) is considered to have occurred when marine mammals are 
exposed to sounds at or above 160 dB rms for impulse sounds (e.g., 
impact pile driving) and 120 dB rms for non-pulsed sound (e.g., 
vibratory pile driving), but below injurious thresholds. However, due 
to ongoing anthropogenic noise around Elliott Bay, the ambient sound 
level is higher than 120 dB in this region. Based on underwater sound 
measurements performed by the Washington State Department of 
Transportation in 2011, and following NMFS Northwest Region and 
Northwest Fisheries Science Center's ``Guidance Document: Data 
Collection Methods to Characterize Underwater Background Sound Relevant 
to Marine Mammals in Coastal Nearshore Waters and Rivers of Washington 
and Oregon,'' we assume that the ambient sound level around the 
proposed project area is 123 dB (Laughlin, 2011). Therefore, 123 dB rms 
is used to estimate Level B harassment for non-pulsed sound (e.g., 
vibratory pile driving) in this instance. 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

    The extent of project-generated sound both in and over water was 
calculated for the locations where pile driving would occur in Elliott 
Bay. In the absence of site-specific data, the practical spreading loss 
model was used for determining the extent of sound from a source 
(Davidson, 2004; Thomsen et al., 2006). The model assumes a logarithmic 
coefficient of 15, which equates to sound energy decreasing by 4.5 dB 
with each doubling of distance from the source. To calculate the loss 
of sound energy from one distance to another, the following formula is 
used:

Transmission Loss (dB) = 15 log(D1/D0)

    D1 is the distance from the source for which SPLs need 
to be known, and D0 is the distance from the source for 
which SPLs are known (typically 10 m from the pile). This model also 
solves for the distance at which sound attenuates to various decibel 
levels (e.g., a threshold or background level). The following equation 
solves for distance:

D1 = D0 x 10(TL/15)

where TL stands for transmission loss (the difference in decibel levels 
between D0 and D1). For example, using the 
distance to an injury threshold (D1), the area of effect is 
calculated as the area of a circle, [pi]r\2\, where r (radius) is the 
distance to the threshold or background. If a landform or other 
shadowing element interrupts the spread of sound within the threshold 
distance, then the area of effect truncates at the location of the 
shadowing element.
    Sound levels are highly dependent on environmental site conditions. 
Therefore, published hydroacoustic monitoring data for projects with 
similar site conditions as the Elliott Bay Seawall project were 
considered (Caltrans, 2009 and WSDOT, 2011a). Based on these data and 
the noise attenuation practical spreading model, also used for pile 
driving activities done by the Washington State Department of 
Transportation and the Washington State Ferries, the sound attenuation 
distances summarized in Table 5 have been identified for in-water pile 
installation. Distance thresholds that account for each pile-related 
activity and pile type proposed for the Elliott Bay Seawall project are 
presented in Table 6.

   Table 5--Summary of Near-Source (10-m) Unattenuated Sound Pressures for In-Water Pile Installation Using an
                                  Impact Hammer and Vibratory Driver/Extractor
----------------------------------------------------------------------------------------------------------------
                                                                                      Average sound pressure
                                                                  Relative water          measured in dB
    Pile type and approximate size               Method              depth (m)   -------------------------------
                                                                                       Peak             RMS
----------------------------------------------------------------------------------------------------------------
Creosote-treated 14-inch-diameter       Vibratory removal.......              15             164             150
 timber pile.
16.5-inch-diameter precast concrete     Impact..................              15             188             176
 octagonal pile.
Steel sheet pile pair; 48-inches in     Vibratory (installation               15             182             165
 length per pair.                        and removal).
Steel sheet pile pair; 48-inches in     Impact (installation                  15             205             190
 length per pair.                        proofing).
----------------------------------------------------------------------------------------------------------------


                  Table 6--Calculated Distances to Threshold Values for Pile-Related Activities
----------------------------------------------------------------------------------------------------------------
                                             Distance to harassment for         Distance to  harassment  for
          Harassment threshold                        pinnipeds                           cetaceans
----------------------------------------------------------------------------------------------------------------
                                      24-inch Steel Sheet Pile (vibratory)
----------------------------------------------------------------------------------------------------------------
Level A (180 and 190 dB)................  0.2 m (0.7 ft)..................  1 m (3.3 ft).
Level B (123 dB)........................  6,276 m (3.9 mi)................  6,276 m (3.9 mi).
----------------------------------------------------------------------------------------------------------------
                                 24-inch Steel Sheet Pile (impact, unattenuated)
----------------------------------------------------------------------------------------------------------------
Level A (180 and 190 dB)................  10 m (33 ft)....................  46 m (152 ft).
Level B (160 dB)........................  1,000 m (3,280 ft)..............  1,000 m (3,280 ft).
----------------------------------------------------------------------------------------------------------------
                                  24-inch Concrete Pile (impact, unattenuated)
----------------------------------------------------------------------------------------------------------------
Level A (180 and 190 dB)................  1 m (3.3 ft)....................  5 m (18 ft).
Level B (160 dB)........................  117 m (383 ft)..................  117 m (383 ft).
----------------------------------------------------------------------------------------------------------------

[[Page 22102]]

 
                                  24-inch Concrete Pile (impact, unattenuated)
----------------------------------------------------------------------------------------------------------------
Level A (180 and 190 dB)................  0.5 m (1.8 ft)..................  2.5 m (8.2 ft).
Level B (160 dB)........................  54 m (177 ft)...................  54 m (177 ft).
----------------------------------------------------------------------------------------------------------------

    Most distances to Level A thresholds (for vibratory steel sheet 
pile and impact concrete pile installations) were calculated to be very 
close to the sound source. In other words, the only way a marine mammal 
could be injured by elevated noise levels from pile-related activities 
would be if the animal was located immediately adjacent to the pile 
being driven. However, longer distances to Level A thresholds were 
calculated for impact pile installation for steel sheet piles: 152 ft 
for cetaceans and 33 ft for pinnipeds. Proposed mitigation and 
monitoring measures (discussed later in this document) would make the 
potential for injury unlikely.

Description of Marine Mammals in the Area of the Specified Activity

    Nine marine mammal species, including distinct population segments, 
have the potential to occur in the area of the specified activity 
(Table 7). All nine species have been observed in Puget Sound at 
certain periods of the year and are discussed in further detail below.

                                          Table 7--Marine Mammal Species or Distinct Population Segments That Could Occur in the Proposed Project Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                   Likelihood of
           Common name              Scientific name         ESA status            MMPA status            Abundance        Population  status        occurrence               Seasonality
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Pinnipeds
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific harbor seal.............  Phoca vitulina.....  ....................  ....................  n/a.................  unknown.............  Occasional..........  Year-round
California sea lion.............  Zalophus             ....................  ....................  296,750.............  ....................  Occasional..........  August-April.
                                   californianus.
Steller sea lion................  Eumetopias jubatus.  Threatened..........  Depleted............  58,334-72,223.......  increasing..........  Rare................  August-April.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Cetaceans
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor porpoise.................  Phocoena phocoena..  ....................  ....................  unknown.............  unknown.............  Rare................  Year-round.
Dall's porpoise.................  Phocoenoides dalli.  ....................  ....................  42,000..............  unknown.............  Rare................  Winter-Spring.
Southern resident killer whale    Orcinus orca.......  Endangered..........  ....................  86..................  unknown.............  Occasional..........  Year-round.
 DPS.
Transient killer whale..........  Orcinus orca.......  ....................  ....................  346.................  unknown.............  Rare................  Year-round.
Humpback whale..................  Megaptera            Endangered..........  Depleted............  2,043...............  increasing..........  Rare................  February-June.
                                   novaengliae.
Gray whale......................  Eschrichtius         ....................  ....................  18,000..............  increasing..........  Rare................  January-September.
                                   robustus.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Harbor Seal

    Species Description--Harbor seals, which are members of the Phocid 
family (true seals), inhabit coastal and estuarine waters and shoreline 
areas from Baja California, Mexico to western Alaska. For management 
purposes, differences in mean pupping date (i.e., birthing) (Temte, 
1986), movement patterns (Jeffries, 1985; Brown, 1988), pollutant loads 
(Calambokidis et al., 1985) and fishery interactions have led to the 
recognition of three separate harbor seal stocks along the west coast 
of the continental U.S. (Boveng, 1988). The three distinct stocks are: 
(1) Inland waters of Washington (including Hood Canal, Puget Sound, and 
the Strait of Juan de Fuca out to Cape Flattery), (2) outer coast of 
Oregon and Washington, and (3) California (Carretta et al. 2007b). The 
seals that could potentially be in the project area are from the inland 
waters of Washington stock.
    The average weight for adult seals is about 180 lb (82 kg) and 
males are typically slightly larger than females. Male harbor seals 
weigh up to 245 lb (111 kg) and measure approximately 5 ft (1.5 m) in 
length. The basic color of harbor seals' coat is gray and mottled but 
highly variable, from dark with light color rings or spots to light 
with dark markings (NMFS, 2008c).
    Status--In 1999, the mean count of harbor seals occurring in 
Washington's inland waters was 9,550 animals (Jeffries et al., 2003). 
Radio-tagging studies conducted at six locations collected information 
on haulout patterns of harbor seals in 1991 and 1992, resulting in a 
correction factor of 1.53 to account for animals in the water that are 
missed during the aerial surveys (Huber et al., 2001). Using this 
correction factor results in a population estimate of 14,612 for the 
Washington inland waters stock of harbor seals (Jeffries et al., 2003). 
Although this abundance estimate represents the best scientific 
information available, per NMFS stock assessment policy it is not 
considered current because it is more than 8 years old. Between 1983 
and 1996, the annual rate of increase for this stock was 6 percent 
(Jeffries et al., 1997). The peak count occurred in 1996 and, based on 
a fitted generalized logistic model, the population is thought to be 
stable. Because there is no current estimate of minimum abundance, 
potential biological removal (PBR) cannot be calculated for this stock. 
Harbor seals are not considered to be depleted under the MMPA or listed 
as threatened or endangered under ESA.
    Behavior and Ecology--Harbor seals are non-migratory with local 
movements associated with such factors as tides, weather, season, food 
availability, and reproduction (Scheffer and Slipp, 1944; Fisher, 1952; 
Bigg, 1969, 1981). They are not known to make extensive pelagic 
migrations, although some long distance movement of tagged animals in 
Alaska (174 km), and along the U.S. west coast

[[Page 22103]]

(up to 550 km), have been recorded (Pitcher and McAllister, 1981; Brown 
and Mate, 1983; Herder, 1986). Harbor seals are coastal species, rarely 
found more than 12 mi (20 km) from shore, and frequently occupy bays, 
estuaries, and inlets (Baird, 2001). Individual seals have been 
observed several miles upstream in coastal rivers. Ideal harbor seal 
habitat includes haul-out sites, shelter during the breeding periods, 
and sufficient food (Bjorge, 2002).
    Harbor seals haul out on rocks, reefs, beaches, and ice and feed in 
marine, estuarine, and occasionally fresh waters. Harbor seals display 
strong fidelity for haul-out sites (Pitcher and Calkins, 1979; Pitcher 
and McAllister, 1981), although human disturbance can affect haul-out 
choice (Harris et al., 2003). Group sizes range from small numbers of 
animals on intertidal rocks to several thousand animals found 
seasonally in coastal estuaries. The harbor seal is the most commonly 
observed and widely distributed pinniped found in Washington (Jeffries 
et al., 2000; ODFW, 2010). Harbor seals use hundreds of sites to rest 
or haul out along the coast and inland waters of Washington, including 
tidal sand bars and mudflats in estuaries, intertidal rocks and reefs, 
beaches, log booms, docks, and floats in all marine areas of the state.
    The harbor seal is the only pinniped species that is found year-
round and breeds in Washington waters (Jeffries et al., 2000). Harbor 
seals mate at sea and females give birth during the spring and summer, 
although the pupping season varies by latitude. Pupping seasons vary by 
geographic region with pups born in the San Juan Islands and eastern 
bays of Puget Sound from June through August. Suckling harbor seal pups 
spend as much as forty percent of their time in the water (Bowen et 
al., 1999).
    Individuals occur along the Elliott Bay shoreline (WSDOT, 2004). 
There is one documented harbor seal haul-out area of less than 100 
animals near Bainbridge Island, about six miles from the proposed 
region of activity and outside of the area of potential effects. The 
haul-out consists of intertidal rocks and reef areas around Blakely 
Rocks (Jeffries et al., 2000).
    Acoustics--In air, harbor seal males produce a variety of low-
frequency (less than 4 kHz) vocalizations, including snorts, grunts, 
and growls. Male harbor seals produce communication sounds in the 
frequency range of 100-1,000 Hz (Richardson et al., 1995). Pups make 
individually unique calls for mother recognition that contain multiple 
harmonics with main energy below 0.35 kHz (Bigg, 1981; Thomson and 
Richardson, 1995). Harbor seals hear nearly as well in air as 
underwater and have lower thresholds than California sea lions (Kastak 
and Schusterman, 1998). Kastak and Schusterman (1998) reported airborne 
low frequency (100 Hz) sound detection thresholds at 65 dB for harbor 
seals. In air, they hear frequencies from 0.25-30 kHz and are most 
sensitive from 6-16 kHz (Richardson, 1995; Terhune and Turnbull, 1995; 
Wolski et al., 2003).
    Adult males also produce underwater sounds during the breeding 
season that typically range from 0.25-4 kHz (duration range: 0.1 s to 
multiple seconds; Hanggi and Schusterman 1994). Hanggi and Schusterman 
(1994) found that there is individual variation in the dominant 
frequency range of sounds between different males, and Van Parijs et 
al. (2003) reported oceanic, regional, population, and site-specific 
variation that could be vocal dialects. In water, they hear frequencies 
from 1-75 kHz (Southall et al., 2007) and can detect sound levels as 
weak as 60-85 dB within that band. They are most sensitive at 
frequencies below 50 kHz; above 60 kHz sensitivity rapidly decreases.

California Sea Lion

    Species Description--California sea lions are members of the 
Otariid family (eared seals). The species, Zalophus californianus, 
includes three subspecies: Z. c. wollebaeki (in the Galapagos Islands), 
Z. c. japonicus (in Japan, but now thought to be extinct), and Z. c. 
californianus (found from southern Mexico to southwestern Canada; 
referred to here as the California sea lion) (Carretta et al., 2007). 
The breeding areas of the California sea lion are on islands located in 
southern California, western Baja California, and the Gulf of 
California (Carretta et al., 2007). These three geographic regions are 
used to separate this subspecies into three stocks: (1) The U.S. stock 
begins at the U.S./Mexico border and extends northward into Canada, (2) 
the Western Baja California stock extends from the U.S./Mexico border 
to the southern tip of the Baja California peninsula, and (3) the Gulf 
of California stock which includes the Gulf of California from the 
southern tip of the Baja California peninsula and across to the 
mainland and extends to southern Mexico (Lowry et al., 1992).
    The California sea lion is sexually dimorphic. Males may reach 
1,000 lb (454 kg) and 8 ft (2.4 m) in length; females grow to 300 lb 
(136 kg) and 6 ft (1.8 m) in length. Their color ranges from chocolate 
brown in males to a lighter, golden brown in females. At around 5 years 
of age, males develop a bony bump on top of the skull called a sagittal 
crest. The crest is visible in the dog-like profile of male sea lion 
heads, and hair around the crest gets lighter with age.
    Status--The entire population of California sea lions cannot be 
counted because all age and sex classes are not ashore at the same 
time. Therefore, pups are counted during the breeding season and the 
number of births is estimated from the pup count. The size of the 
population is then estimated from the number of births and the 
proportion of pups in the population. This most recently resulted in a 
population estimate of 296,750 animals. The PBR level for this stock is 
9,200 sea lions per year. California sea lions are not considered to be 
depleted under the MMPA or listed as threatened or endangered under 
ESA.
    Behavior and Ecology--During the summer, California sea lions breed 
on islands from the Gulf of California to the Channel Islands and 
seldom travel more than about 31 mi (50 km) from the islands (Bonnell 
et al., 1983). The primary rookeries are located in the California 
Channel Islands (Le Boeuf and Bonnell, 1980; Bonnell and Dailey, 1993). 
Their distribution shifts to the northwest in fall and to the southeast 
during winter and spring, probably in response to changes in prey 
availability (Bonnell and Ford, 1987).
    The non-breeding distribution extends from Baja California north to 
Alaska for males, and encompasses the waters of California and Baja 
California for females (Reeves et al., 2008; Maniscalco et al., 2004). 
In the non-breeding season, an estimated 3,000 to 5,000 adult and sub-
adult males migrate northward along the coast to central and northern 
California, Oregon, Washington, and Vancouver Island from September to 
May (Jeffries et al., 2000) and return south the following spring 
(Mate, 1975; Bonnell et al., 1983). During migration, they are 
occasionally sighted hundreds of miles offshore (Jefferson et al., 
1993). Females and juveniles tend to stay closer to the rookeries 
(Bonnell et al., 1983). California sea lions do not breed in 
Washington, but are typically observed in Washington between August and 
April, after they have dispersed from breeding colonies.
    California sea lions feed on a wide variety of prey, including many 
species of fish and squid (Everitt et al., 1981; Roffe and Mate, 1984; 
Antonelis et al., 1990; Lowry et al., 1991). In some locations where 
salmon runs exist, California sea lions also feed on returning adult 
and out-migrating juvenile salmonids (London, 2006).

[[Page 22104]]

Sexual maturity occurs at around 4-5 years of age for California sea 
lions (Heath, 2002). California sea lions are gregarious during the 
breeding season and social on land during other times.
    The California sea lion is the most frequently sighted pinniped 
found in Washington waters and uses haul-out sites along the outer 
coast, Strait of Juan de Fuca, and in Puget Sound. Haul-out sites are 
located on jetties, offshore rocks and islands, log booms, marine 
docks, and navigation buoys. This species is also frequently seen 
resting in the water together in groups in Puget Sound (Jeffries et 
al., 2000). There are three documented California sea lion haul-outs 
near the proposed project area; all are located about six miles away 
and outside of the area of potential effects. These haul-outs include a 
yellow `T' buoy off Alki Point, a yellow `SG' buoy between West Point 
and Skiff Point, and a red buoy off Restoration Point (Jeffries et al., 
2000). The haul-outs have all been identified to have populations less 
than 100 individuals. It is assumed that California sea lions seen in 
and around the proposed project area use these haul-outs.
    Acoustics--On land, California sea lions make incessant, raucous 
barking sounds; these have most of their energy at less than 2 kHz 
(Schusterman et al., 1967). Males vary both the number and rhythm of 
their barks depending on the social context; the barks appear to 
control the movements and other behavior patterns of nearby 
conspecifics (Schusterman, 1977). Females produce barks, squeals, 
belches, and growls in the frequency range of 0.25-5 kHz, while pups 
make bleating sounds at 0.25-6 kHz. California sea lions produce two 
types of underwater sounds: clicks (or short-duration sound pulses) and 
barks (Schusterman et al., 1966, 1967; Schusterman and Baillet, 1969). 
All of these underwater sounds have most of their energy below 4 kHz 
(Schusterman et al., 1967).
    The range of maximal hearing sensitivity for California sea lions 
underwater is between 1-28 kHz (Schusterman et al., 1972). Functional 
underwater high frequency hearing limits are between 35-40 kHz, with 
peak sensitivities from 15-30 kHz (Schusterman et al., 1972). The 
California sea lion shows relatively poor hearing at frequencies below 
1 kHz (Kastak and Schusterman, 1998). Peak hearing sensitivities in air 
are shifted to lower frequencies; the effective upper hearing limit is 
approximately 36 kHz (Schusterman, 1974). The best range of sound 
detection is from 2-16 kHz (Schusterman, 1974). Kastak and Schusterman 
(2002) determined that hearing sensitivity generally worsens with 
depth--hearing thresholds were lower in shallow water, except at the 
highest frequency tested (35 kHz), where this trend was reversed. 
Octave band sound levels of 65-70 dB above the animal's threshold 
produced an average temporary threshold shift (TTS; discussed later in 
Potential Effects of the Specified Activity on Marine Mammals) of 4.9 
dB in the California sea lion (Kastak et al., 1999).

Steller Sea Lions

    Species Description--Steller sea lions are the largest members of 
the Otariid (eared seal) family. Steller sea lions show marked sexual 
dimorphism, in which adult males are noticeably larger and have 
distinct coloration patterns from females. Males average about 1,500 lb 
(680 kg) and 10 ft (3 m) in length; females average about 700 lb (318 
kg) and 8 ft (2.4 m) in length. Adult females have a tawny to silver-
colored pelt. Males are characterized by dark, dense fur around their 
necks, giving a mane-like appearance, and light tawny coloring over the 
rest of their body (NMFS, 2008a). Steller sea lions are distributed 
mainly around the coasts to the outer continental shelf along the North 
Pacific Ocean rim from northern Hokkaido, Japan through the Kuril 
Islands and Okhotsk Sea, Aleutian Islands and central Bering Sea, 
southern coast of Alaska and south to California. The population is 
divided into the western and the eastern distinct population segments 
(DPSs) at 144[deg] W (Cape Suckling, Alaska). The western DPS includes 
Steller sea lions that reside in the central and western Gulf of 
Alaska, Aleutian Islands, as well as those that inhabit coastal waters 
and breed in Asia (e.g., Japan and Russia). The eastern DPS extends 
from California to Alaska, including the Gulf of Alaska. Animals found 
in the proposed project area would be from the eastern DPS (NMFS, 
1997a; Loughlin, 2002; Angliss and Outlaw, 2005).
    Status--Steller sea lions were listed as threatened range-wide 
under the ESA in 1990. After division into two DPSs, the western DPS 
was listed as endangered under the ESA in 1997, while the eastern DPS 
remained classified as threatened. The eastern DPS breeds in rookeries 
located in southeast Alaska, British Columbia, Oregon, and California. 
While some pupping has been reported recently along the coast of 
Washington, there are no active rookeries in Washington. A final 
revised species recovery plan addresses both DPSs (NMFS, 2008a).
    NMFS designated critical habitat for Steller sea lions in 1993. 
Critical habitat is associated with breeding and haul-out sites in 
Alaska, California, and Oregon, and includes so-called `aquatic zones' 
that extend 3,000 ft (900 m) seaward in state and federally managed 
waters from the baseline or basepoint of each major rookery in Oregon 
and California (NMFS, 2008a). Three major rookery sites in Oregon 
(Rogue Reef, Pyramid Rock, and Long Brown Rock and Seal Rock on Orford 
Reef at Cape Blanco) and three rookery sites in California (Ano Nuevo, 
Southeast Farallon, and Sugarloaf Island and Cape Mendocino) are 
designated critical habitat (NMFS, 1993). There is no designated 
critical habitat within the proposed project area.
    Factors that have previously been identified as threats to Steller 
sea lions include reduced food availability, possibly resulting from 
competition with commercial fisheries; incidental take and intentional 
kills during commercial fish harvests; subsistence take; entanglement 
in marine debris; disease; pollution; and harassment. Steller sea lions 
are also sensitive to disturbance at rookeries (during pupping and 
breeding) and haul-out sites.
    The Recovery Plan for the Steller Sea Lion (NMFS, 2008a) states 
that the overall abundance of Steller sea lions in the eastern DPS has 
increased for a sustained period of at least three decades, and that 
pup production has increased significantly, especially since the mid-
1990s. Between 1977 and 2002, researchers estimated that overall 
abundance of the eastern DPS had increased at an average rate of 3.1 
percent per year (NMFS, 2008a; Pitcher et al., 2007). NMFS' most recent 
stock assessment report estimates that population for the eastern DPS 
is a minimum of 52,847 individuals; this estimate is not corrected for 
animals at sea, and actual population is estimated to be within the 
range 58,334 to 72,223 (Allen and Angliss, 2010). The minimum count for 
Steller sea lions in Washington was 516 in 2001 (Pitcher et al., 2007).
    In the far southern end of Steller sea lion range (Channel Islands 
in southern California), population declined significantly after the 
1930s--probably due to hunting and harassment (Bartholomew and 
Boolootian, 1960; Bartholomew, 1967)--and several rookeries and haul-
outs have been abandoned. The lack of recolonization at the 
southernmost portion of the range (e.g., San Miguel Island rookery), 
despite stability in the non-pup portion of the overall California 
population, is likely a response to a suite of factors including 
changes in ocean conditions (e.g., warmer temperatures) that may be

[[Page 22105]]

contributing to habitat changes that favor California sea lions over 
Steller sea lions (NMFS, 2007) and competition for space on land, and 
possibly prey, with species that have experienced explosive growth over 
the past three decades (e.g., California sea lions and northern 
elephant seals [Mirounga angustirostris]). Although recovery in 
California has lagged behind the rest of the DPS, this portion of the 
DPS' range has recently shown a positive growth rate (NMML, 2012). 
While non-pup counts in California in the 2000s are only 34 percent of 
pre-decline counts (1927-1947), the population has increased 
significantly since 1990. Despite the abandonment of certain rookeries 
in California, pup production at other rookeries in California has 
increased over the last 20 years and, overall, the eastern DPS has 
increased at an average annual growth rate of 4.3 percent per year for 
30 years. Even though these rookeries might not be recolonized, their 
loss has not prevented the increasing abundance of Steller sea lions in 
California or in the eastern DPS overall.
    Because the eastern DPS of Steller sea lion is currently listed as 
threatened under the ESA, it is therefore designated as depleted and 
classified as a strategic stock under the MMPA. However, the eastern 
DPS has been considered a potential candidate for removal from listing 
under the ESA by the Steller sea lion recovery team and NMFS (NMFS, 
2008), based on observed annual rates of increase. Although the stock 
size has increased, the status of this stock relative to its Optimum 
Sustainable Population (OSP) size is unknown. The overall annual rate 
of increase of the eastern stock has been consistent and long-term, and 
may indicate that this stock is reaching OSP.
    Behavior and Ecology--Steller sea lions forage near shore and in 
pelagic waters. They are capable of traveling long distances in a 
season and can dive to approximately 1,300 ft (400 m) in depth. They 
also use terrestrial habitat as haul-out sites for periods of rest, 
molting, and as rookeries for mating and pupping during the breeding 
season. At sea, they are often seen alone or in small groups, but may 
gather in large rafts at the surface near rookeries and haul-outs. 
Steller sea lions prefer the colder temperate to sub-arctic waters of 
the North Pacific Ocean. Haul-outs and rookeries usually consist of 
beaches (gravel, rocky or sand), ledges, and rocky reefs. In the Bering 
and Okhotsk Seas, sea lions may also haul-out on sea ice, but this is 
considered atypical behavior (NOAA, 2010a). Steller sea lions are 
opportunistic predators, feeding primarily on fish and cephalopods, and 
their diet varies geographically and seasonally (Bigg, 1985; Merrick et 
al., 1997; Bredesen et al., 2006; Guenette et al., 2006). Foraging 
habitat is primarily shallow, nearshore and continental shelf waters; 
freshwater rivers; and also deep waters (Reeves et al., 2008; Scordino, 
2010).
    Steller sea lions are gregarious animals that often travel or haul 
out in large groups of up to 45 individuals (Keple, 2002). At sea, 
groups usually consist of female and subadult males; adult males are 
usually solitary while at sea (Loughlin, 2002). In the Pacific 
Northwest, breeding rookeries are located in British Columbia, Oregon, 
and northern California. Steller sea lions form large rookeries during 
late spring when adult males arrive and establish territories (Pitcher 
and Calkins, 1981). Large males aggressively defend territories while 
non-breeding males remain at peripheral sites or haul-outs. Females 
arrive soon after and give birth. Most births occur from mid-May 
through mid-July, and breeding takes place shortly thereafter. Most 
pups are weaned within a year. Non-breeding individuals may not return 
to rookeries during the breeding season but remain at other coastal 
haul-outs (Scordino, 2006).
    The nearest Steller sea lion haul-out to the proposed project area 
is about six miles away and outside the area of potential effects. This 
haul-out is composed of net pens offshore of the south end of 
Bainbridge Island. The population of Steller sea lions at this haul-out 
has been estimated at less than 100 individuals (Jeffries et al., 
2000). Review of many anecdotal accounts indicates that this species is 
rarely seen in the area of potential effects.
    Acoustics--Like all pinnipeds, the Steller sea lion is amphibious; 
while all foraging activity takes place in the water, breeding behavior 
is carried out on land in coastal rookeries (Mulsow and Reichmuth 
2008). On land, territorial male Steller sea lions regularly use loud, 
relatively low-frequency calls/roars to establish breeding territories 
(Schusterman et al., 1970; Loughlin et al., 1987). The calls of females 
range from 0.03 to 3 kHz, with peak frequencies from 0.15 to 1 kHz; 
typical duration is 1.0 to 1.5 sec (Campbell et al., 2002). Pups also 
produce bleating sounds. Individually distinct vocalizations exchanged 
between mothers and pups are thought to be the main modality by which 
reunion occurs when mothers return to crowded rookeries following 
foraging at sea (Mulsow and Reichmuth, 2008).
    Mulsow and Reichmuth (2008) measured the unmasked airborne hearing 
sensitivity of one male Steller sea lion. The range of best hearing 
sensitivity was between 5 and 14 kHz. Maximum sensitivity was found at 
10 kHz, where the subject had a mean threshold of 7 dB. The underwater 
hearing threshold of a male Steller sea lion was significantly 
different from that of a female. The peak sensitivity range for the 
male was from 1 to 16 kHz, with maximum sensitivity (77 dB re: 1[mu]Pa-
m) at 1 kHz. The range of best hearing for the female was from 16 to 
above 25 kHz, with maximum sensitivity (73 dB re: 1[mu]Pa-m) at 25 kHz. 
However, because of the small number of animals tested, the findings 
could not be attributed to either individual differences in sensitivity 
or sexual dimorphism (Kastelein et al., 2005).

Harbor Porpoise

    Species Description--Harbor porpoises inhabit northern temperate 
and subarctic coastal and offshore waters. They are commonly found in 
bays, estuaries, harbors, and fjords less than 650 ft (200 m) deep. In 
the North Atlantic, they range from West Greenland to Cape Hatteras, 
North Carolina and from the Barents Sea to West Africa. In the North 
Pacific, they are found from Japan north to the Chukchi Sea and from 
Monterey Bay, California to the Beaufort Sea. There are ten stocks of 
harbor porpoises in U.S. waters: Bering Sea, Gulf of Alaska, Gulf of 
Maine-Bay of Fundy, Inland Washington, Monterey Bay, Morro Bay, 
Northern California-Southern Oregon, Oregon-Washington Coastal, San 
Francisco-Russian River, and Southeast Alaska. Harbor porpoises that 
could potentially be in the proposed project area would be part of the 
Inland Washington stock.
    Harbor porpoises have a small, robust body with a short, blunt 
beak. They typically weigh 135-170 pounds and are about 5 to 5.5 ft 
(1.5 to 1.7 m) in length. Females are slightly larger than males. All 
animals are dark gray with a white underside.
    Status--Aerial surveys of the Strait of Juan de Fuca, San Juan 
Islands, Gulf Islands, and Strait of Georgia (which includes waters 
inhabited by the Washington Inland stock of harbor porpoise) were 
conducted during August of 2002 and 2003. The average abundance 
estimate resulting from those surveys is 3,123. When corrected for 
availability and perception bias, the estimated abundance for the 
Washington Inland stock in 2002/2003 is 10,682 animals. However, 
because the most recent abundance estimate is more

[[Page 22106]]

than 8 years old, there is no current estimate of abundance available 
for this stock. Because there is no current estimate of minimum 
abundance, a PBR cannot be calculated for this stock. There is also no 
reliable data on long-term population trends of harbor porpoise for 
most waters of Oregon, Washington, or British Columbia. Harbor 
porpoises are not considered to be depleted under the MMPA or listed as 
threatened or endangered under the ESA.
    Behavior and Ecology--Harbor porpoises are known to occur year-
round in the inland trans-boundary waters of Washington and British 
Columbia and along the Oregon/Washington coast. Although differences in 
density exist between coastal Oregon/Washington and inland Washington 
waters, a specific stock boundary line cannot be identified based on 
biological or genetic differences. However, harbor porpoise movements 
and rates of intermixing within the eastern North Pacific are 
restricted, and there has been a significant decline in harbor porpoise 
sightings within southern Puget Sound since the 1940s, and today, 
harbor porpoise are rarely observed. Recently, there have been 
confirmed sightings of harbor porpoise in central Puget Sound (NMFS, 
2006); however, no reports of harbor porpoises in the area of potential 
effects were made during 2011 (Whale Museum, 2011).
    Harbor porpoises are non-social animals usually seen in groups of 
two to five animals. They feed on demersal and benthic species, mainly 
schooling fish and cephalopods.
    Acoustics--Harbor porpoises are considered high-frequency cetaceans 
and their estimated auditory bandwidth ranges from 200 Hz to 180 kHz. 
Some studies suggest that harbor porpoises may be more sensitive to 
sound than other odontocetes (Lucke et al., 2009; Kastelein et al., 
2011). In general, toothed whales produce a wide variety of sounds, 
which include species-specific broadband ``clicks'' with peak energy 
between 10 and 200 kHz, individually variable ``burst pulse'' click 
trains, and constant frequency or frequency-modulated (FM) whistles 
ranging from 4 to 16 kHz (Wartzok and Ketten, 1999). The general 
consensus is that the tonal vocalizations (whistles) produced by 
toothed whales play an important role in maintaining contact between 
dispersed individuals, while broadband clicks are used during 
echolocation (Wartzok and Ketten, 1999). Burst pulses have also been 
strongly implicated in communication, with some scientists suggesting 
that they play an important role in agonistic encounters (McCowan and 
Reiss, 1995), while others have proposed that they represent 
``emotive'' signals in a broader sense, possibly representing graded 
communication signals (Herzing, 1996). Sperm whales, however, are known 
to produce only clicks, which are used for both communication and 
echolocation (Whitehead, 2003). Most of the energy of toothed whale 
social vocalizations is concentrated near 10 kHz, with source levels 
for whistles as high as 100 to 180 dB re 1 [mu]Pa at 1 m (Richardson et 
al., 1995). No odontocete has been shown audiometrically to have acute 
hearing (<80 dB re 1 [mu]Pa) below 500 Hz (DoN, 2001). Sperm whales 
produce clicks, which may be used to echolocate (Mullins et al., 1988), 
with a frequency range from less than 100 Hz to 30 kHz and source 
levels up to 230 dB re 1 [mu]Pa 1 m or greater (Mohl et al., 2000).

Dall's Porpoise

    Species Description--Dall's porpoises are common in the North 
Pacific Ocean, preferring temperate or cooler waters that are more than 
600 ft (180 m) deep and with temperatures between 36-63 degrees 
Fahrenheit. For management purposes, Dall's porpoises inhabiting U.S. 
waters have been divided into two stocks: the Alaska stock and the 
California/Oregon/Washington stock. Dall's porpoises that could 
potentially be in the project area would be from the California/Oregon/
Washington stock.
    Dall's porpoises are fast swimming members of the porpoise family. 
They can weigh up to 480 pounds and grow up to 8 ft (2.4 m) long. They 
are identified by a dark gray or black body with variable contrasting 
white panels. These markings and colorations vary with geographic 
location and life stage.
    Status--Dall's porpoise distribution in this region is highly 
variable between years and appears to be affected by oceanographic 
conditions. The most recent abundance estimate (42,000 animals) relies 
on estimates from 2005 and 2008 vessel-based line transect surveys off 
the coasts of California, Oregon, and Washington. Insufficient data are 
available to estimate current population trends. However, Dall's 
porpoises are generally considered reasonably abundant. There are an 
estimated 130,000 individuals in U.S. waters, including 76,000-99,500 
off the Pacific coast (California, Oregon, and Washington) (NMFS, 
2012). The PBR level for this stock is 257 animals per year. Dall's 
porpoises are not considered depleted under the MMPA or listed as 
threatened or endangered under the ESA.
    Behavior and Ecology--Dall's porpoises can be found in offshore, 
inshore, and nearshore oceanic waters and are endemic to temperate 
waters of the North Pacific Ocean. Off the west coast, they are 
commonly seen in shelf, slope, and offshore waters. Sighting patterns 
from aerial and shipboard surveys conducted in California, Oregon, and 
Washington at different times suggest that north-south movement between 
these states occurs as oceanographic conditions change, both on 
seasonal and inter-annual scales. Only rarely have reports of Dall's 
porpoises been made for the area of potential effects. They feed on 
small schooling fish, mid- and deep-water fish, cephalopods, and 
occasionally crabs and shrimp. Feeding usually occurs at night when 
their prey vertically migrates up toward the water's surface. Dall's 
porpoises are capable of diving up to 1,640 ft (500 m) in order to 
reach their prey.
    Acoustics--Dall's porpoises are considered high-frequency cetaceans 
their estimated auditory bandwidth ranges from 200 Hz to 180 kHz. 
General acoustic information on toothed whales was provided in the 
Harbor Porpoise section and is not repeated here.

Killer Whale

    Species Description--Killer whales are the most widely distributed 
cetacean species in the world. Killer whales prefer colder waters, with 
the greatest abundances found within 800 km of major continents. Along 
the west coast of North America, killer whales occur along the entire 
Alaskan coast, in British Columbia and Washington inland waterways, and 
along the outer coasts of Washington, Oregon, and California. Based on 
morphology, ecology, genetics, and behavior, pods have been labeled as 
`resident,' `transient,' and `offshore.' The distinct population 
segment of Southern resident killer whales is expected to have the 
highest potential of occurrence in the proposed project area. Transient 
killer whales may occasionally occur and are discussed where 
appropriate.
    Killer whales are members of the dolphin family and can grow as 
long as 32 ft (9.8 m) and weigh as much as 22,000 pounds. They are 
identified by their large size and distinctive black and white 
appearance. Killer whales are highly social animals and often travel in 
groups of up to 50 animals. However, the Southern resident DPS is made 
up of three pods, and the one most likely to occur in the proposed 
project area--the J pod--has about 26 animals.
    Status--The Eastern North Pacific Southern Resident stock is a 
trans-boundary stock including killer whales in inland Washington and 
southern British Columbia waters. Photo-

[[Page 22107]]

identification of individual whales through the years has resulted in a 
substantial understanding of this stock's structure, behaviors, and 
movements. In 1993, the three pods comprising this stock totaled 96 
killer whales (Ford et al., 1994). The population increased to 99 
whales in 1995, then declined to 79 whales in 2001, and most recently 
number 86 whales in 2010 (Ford et al., 2000, Center for Whale Research, 
unpubl. data).
    The Southern Resident killer whale is listed as endangered under 
the ESA and as strategic under the MMPA. Critical habitat was 
designated in 2006 and includes all marine waters greater than 20 ft in 
depth. Critical habitat for this DPS includes the summer core area in 
Haro Strait and waters around the San Juan Islands; Puget Sound; and 
the Strait of Juan de Fuca (NOAA, 2006). On November 27, 2012, NMFS 
announced a 90-day finding on a petition to delist the Southern 
Resident killer whale DPS (77 FR 70733, November 27, 2012). NMFS found 
that the petition action may be warranted and initiated a status review 
of Southern Resident killer whales to determine further action. The 
request for information period closed on January 28, 2013 and NMFS has 
not yet made a determination. Transient killer whales are not listed 
under the ESA, but are considered depleted under the MMPA.
    Behavior and Ecology--Killer whales feed on a variety of fish, 
marine mammals, and sharks, depending on their population and 
geographic location. Resident populations in the eastern North Pacific 
feed mainly on salmonids, such as Chinook and chum salmon.
    A long-term database maintained by the Whale Museum monitors 
sightings and geospatial locations of Southern Resident killer whale, 
among other marine mammals, in inland waters of Washington State. Data 
are largely based on opportunistic sightings from a variety of sources 
(i.e., public reports, commercial whale watching, Soundwatch, Lime Kiln 
State Park land-based observations, and independent research reports), 
but are regarded as a robust but difficult to quantify inventory of 
occurrences. The data provide the most comprehensive assemblage of 
broad-scale habitat use by the DPS in inland waters.
    Based on reports from 1990 to 2008, the greatest number of unique 
killer whale sighting-days near or in the area of potential effects 
occurred from November through January, although observations were made 
during all months except May (Osborne, 2008). Most observations were of 
Southern Resident killer whales passing west of Alki Point (82 percent 
of all observations), which lies on the edge or outside the area of 
potential effects; a pattern potentially due to the high level of human 
disturbance or highly degraded habitat features currently found within 
Elliott Bay. Of the pods that compose this DPS, the J pod, with an 
estimated 26 members, is the pod most likely to appear year-round near 
the San Juan Islands, in the lower Puget Sound near Seattle, and in 
Georgia Strait at the mouth of the Fraser River. The J pod tends to 
frequent the west side of San Juan Island in mid to late spring (CWR, 
2011). An analysis of 2011 sightings described an estimated 93 
sightings of Southern Resident killer whales near the area of potential 
effects (Whale Museum, 2011). During this same analysis period, 12 
transient killer whales were also observed near the area of potential 
effects. The majority of all sightings in this area are of groups of 
killer whales moving through the main channel between Bainbridge Island 
and Elliott Bay and outside the area of potential effects (Whale 
Museum, 2011). The purely descriptive format of these observations make 
it impossible to discern what proportion of the killer whales observed 
entered into the area of potential effects; however, it is assumed 
individuals may enter into this area on occasion.
    Acoustics--Killer whales are considered mid-frequency cetaceans and 
their estimated auditory bandwidth ranges from 150 Hz to 160 kHz. 
General acoustics information for toothed whales was provided in the 
Harbor Porpoise section and is not repeated here.

Humpback Whale

    Species Description--Humpbacks are large, dark grey baleen whales 
with some areas of white. They can grow up to 60 ft (18 m) long and 
weigh up to 40 tons. They are well known for their long pectoral fins, 
which can reach up to 15 ft (4.6 m) in length. Humpback whales live in 
all major oceans from the equator to sub-polar latitudes.
    In the North Pacific, there are at least three separate 
populations: the California/Oregon/Washington stock, the Central North 
Pacific stock, and the Western North Pacific stock. Any humpbacks that 
may occur in the proposed project area would be part of the California/
Oregon/Washington stock.
    Status--The best estimate of abundance for the California/Oregon/
Washington stock is 2,043 animals and based on a mark-recapture study. 
Ship surveys provide some indication that humpback whales increased in 
abundance in California coastal waters between 1979-1980 and 1991 
(Barlow, 1994) and between 1991 and 2005 (Barlow and Forney, 2007; 
Forney, 2007), but this increase was not steady, and estimates showed a 
slight dip in 2001. Mark-recapture population estimates have shown a 
long-term increase of about 7.5 percent per year (Calambokidis, 2009), 
although there have been short-term declines during this period, 
probably due to oceanographic variability. Population estimates for the 
entire North Pacific have also increased substantially and the growth 
rate implied by these estimates (6-7 percent) is consistent with the 
recently observed growth rate of the California/Oregon/Washington stock 
(NMFS, 2011).
    As a result of commercial whaling, humpback whales are listed as 
endangered under the ESA throughout their range and also considered 
depleted under the MMPA.
    Behavior and Ecology--Humpback whales complete the farthest 
migration of any mammal each year. During the summer months, the 
California/Oregon/Washington stock spends the majority of their time 
feeding along the coast of North America. Humpback whales filter feed 
on tiny crustaceans (mostly krill), plankton, and small fish. This 
stock then spends winter in coastal Central America and Mexico engaging 
in mating activities.
    Humpback whales are found in coastal waters of Washington as they 
migrate from feeding grounds to winter breeding grounds. Humpback 
whales are considered rare visitors to Puget Sound and are not observed 
in the area every year. Past sightings around Puget Sound and Hood 
Canal have taken place well away from the proposed project area; 
however, it is possible that they may occur at least once during the 
proposed construction period.
    Acoustics--Baleen whale vocalizations are composed primarily of 
frequencies below 1 kHz, and some contain fundamental frequencies as 
low as 16 Hz (Watkins et al., 1987; Richardson et al., 1995; Rivers, 
1997; Moore et al., 1998; Stafford et al., 1999; Wartzok and Ketten, 
1999) but can be as high as 24 kHz for humpback whales (Au et al., 
2006). Clark and Ellison (2004) suggested that baleen whales use low-
frequency sounds not only for long-range communication, but also as a 
simple form of echo ranging, using echoes to navigate and orient 
relative to physical features of the ocean. Information on auditory 
function in baleen whales is extremely lacking. Sensitivity to low-
frequency sound by

[[Page 22108]]

baleen whales has been inferred from observed vocalization frequencies, 
observed reactions to playback of sounds, and anatomical analyses of 
the auditory system. Although there is apparently much variation, the 
source levels of most baleen whale vocalizations lie in the range of 
150-190 dB re 1 [micro]Pa at 1 m. Low-frequency vocalizations made by 
baleen whales and their corresponding auditory anatomy suggest that 
they have good low-frequency hearing (Ketten, 2000), although specific 
data on sensitivity, frequency or intensity discrimination, or 
localization abilities are lacking.

Gray Whale

    Species Description--Gray whales are large baleen whales found 
mainly in shallow coastal waters of the North Pacific Ocean. They are 
identified by their mottled gray bodies, small eyes, and dorsal hump 
(not a dorsal fin). The can weigh up to 80,000 pounds and grow up to 50 
ft (15 m) in length.
    There are two isolated geographic distributions of gray whales in 
the North Pacific Ocean: the Eastern North Pacific stock and the 
Western North Pacific stock. Any gray whales occurring around the 
proposed project area would be part of the Eastern North Pacific stock, 
which includes the west coast of North America.
    Status--Systematic counts of Eastern North Pacific gray whales 
migrating south along the Central California coast have been conducted 
by shore-based observers at Granite Canyon most years since 1967. The 
most recent abundance estimates are based on counts made during the 
1997-1998, 2000-2001, and 2001-2002 southbound migrations, and range 
from about 18,000 to 30,000 animals. The population size of the Eastern 
North Pacific stock has been increasing over the past several decades 
despite an unusual mortality event in 1999 and 2000. The estimated 
annual rate of increase is 3.2-3.3 percent. In contrast the Western 
North Pacific population remains highly depleted.
    While the Western North Pacific population is listed as endangered 
under the ESA, the Eastern North Pacific population was delisted from 
the ESA in 1994 after reaching a `recovered' status. The Eastern North 
Pacific stock is not considered depleted under the MMPA.
    Behavior and Ecology--Gray whales feed in shallow waters, usually 
150-400 ft deep and adults consume over 1 ton of food per day during 
peak feeding periods. The gray whale is unique among cetaceans as a 
bottom-feeder that rolls onto its side, sucking up sediment from the 
seabed. Benthic organisms that live in the sediment are trapped by the 
baleen plates as water and silt are filtered out. Gray whales typically 
travel alone or in small, unstable groups.
    Eastern North Pacific gray whales occur frequently off the coast of 
Washington during their southerly migration in November and December, 
and northern migration from March through May (Rugh et al., 2001; Rice 
et al., 1984). Gray whales are observed in Washington inland waters 
regularly between the months of January and September, with peaks 
between March and May. Gray whale sightings are typically reported in 
February through May and include an observation of a gray whale off the 
ferry terminal at Pier 52 heading toward the East Waterway in March 
2010 (CWR, 2011; Whale Museum, 2012). Three gray whales were observed 
near the project area during 2011, but the narrative format of the 
observations makes it difficult to discern whether these individuals 
entered into the area of potential effects. It is assumed that gray 
whales might rarely occur in the area of potential effects.
    Acoustics--Gray whale vocalizations and auditory function, like all 
baleen whale acoustics, is similar to that of humpback whales, 
described above. That information is not repeated here.

Potential Effects of the Specified Activity on Marine Mammals

    SDOT's in-water construction activities (i.e., pile driving and 
removal) would introduce elevated levels of sound into the marine 
environment and have the potential to adversely impact marine mammals. 
The potential effects of sound from the proposed activities associated 
with the Elliott Bay Seawall project may include one or more of the 
following: tolerance; masking of natural sounds; behavioral 
disturbance; non-auditory physical effects; and temporary or permanent 
hearing impairment (Richardson et al., 1995). However, for reasons 
discussed later in this document, it is unlikely that there would be 
any cases of temporary or permanent hearing impairment resulting from 
these activities. As outlined in previous NMFS documents, the effects 
of sound on marine mammals are highly variable, and can be categorized 
as follows (based on Richardson et al., 1995):
     The sound may be too weak to be heard at the location of 
the animal (i.e., lower than the prevailing ambient sound level, the 
hearing threshold of the animal at relevant frequencies, or both);
     The sound may be audible but not strong enough to elicit 
any overt behavioral response;
     The sound may elicit reactions of varying degrees and 
variable relevance to the well-being of the marine mammal; these can 
range from temporary alert responses to active avoidance reactions such 
as vacating an area until the stimulus ceases, but potentially for 
longer periods of time;
     Upon repeated exposure, a marine mammal may exhibit 
diminishing responsiveness (habituation), or disturbance effects may 
persist; the latter is most likely with sounds that are highly variable 
in characteristics and unpredictable in occurrence, and associated with 
situations that a marine mammal perceives as a threat;
     Any anthropogenic sound that is strong enough to be heard 
has the potential to result in masking, or reduce the ability of a 
marine mammal to hear biological sounds at similar frequencies, 
including calls from conspecifics and underwater environmental sounds 
such as surf sound;
     If mammals remain in an area because it is important for 
feeding, breeding, or some other biologically important purpose even 
though there is chronic exposure to sound, it is possible that there 
could be sound-induced physiological stress; this might in turn have 
negative effects on the well-being or reproduction of the animals 
involved; and
     Very strong sounds have the potential to cause a temporary 
or permanent reduction in hearing sensitivity, also referred to as 
threshold shift. In terrestrial mammals, and presumably marine mammals, 
received sound levels must far exceed the animal's hearing threshold 
for there to be any temporary threshold shift (TTS). For transient 
sounds, the sound level necessary to cause TTS is inversely related to 
the duration of the sound. Received sound levels must be even higher 
for there to be risk of permanent hearing impairment (PTS). In 
addition, intense acoustic or explosive events may cause trauma to 
tissues associated with organs vital for hearing, sound production, 
respiration and other functions. This trauma may include minor to 
severe hemorrhage.

Tolerance

    Numerous studies have shown that underwater sounds from industrial 
activities are often readily detectable by marine mammals in the water 
at distances of many kilometers. However, other studies have shown that 
marine mammals at distances more than a few kilometers away often show 
no apparent response to industrial activities of various types (Miller 
et al., 2005). This is often true even in cases when the

[[Page 22109]]

sounds must be readily audible to the animals based on measured 
received levels and the hearing sensitivity of that mammal group. 
Although various baleen whales, toothed whales, and (less frequently) 
pinnipeds have been shown to react behaviorally to underwater sound 
from sources such as airgun pulses or vessels under some conditions, at 
other times, mammals of all three types have shown no overt reactions 
(e.g., Malme et al., 1986; Richardson et al., 1995; Madsen and Mohl, 
2000; Croll et al., 2001; Jacobs and Terhune, 2002; Madsen et al., 
2002; Miller et al., 2005). In general, pinnipeds seem to be more 
tolerant of exposure to some types of underwater sound than are baleen 
whales. Richardson et al. (1995) found that vessel sound does not seem 
to strongly affect pinnipeds that are already in the water. Richardson 
et al. (1995) went on to explain that seals on haul-outs sometimes 
respond strongly to the presence of vessels and at other times appear 
to show considerable tolerance of vessels, and Brueggeman et al. (1992) 
observed ringed seals (Pusa hispida) hauled out on ice pans displaying 
short-term escape reactions when a ship approached within 0.16-0.31 mi 
(0.25-0.5 km).

Masking

    Masking is the obscuring of sounds of interest to an animal by 
other sounds, typically at similar frequencies. Marine mammals are 
highly dependent on sound, and their ability to recognize sound signals 
amid other sound is important in communication and detection of both 
predators and prey. Background ambient sound may interfere with or mask 
the ability of an animal to detect a sound signal even when that signal 
is above its absolute hearing threshold. Even in the absence of 
anthropogenic sound, the marine environment is often loud. Natural 
ambient sound includes contributions from wind, waves, precipitation, 
other animals, and (at frequencies above 30 kHz) thermal sound 
resulting from molecular agitation (Richardson et al., 1995).
    Background sound may also include anthropogenic sound, and masking 
of natural sounds can result when human activities produce high levels 
of background sound. Conversely, if the background level of underwater 
sound is high (e.g., on a day with strong wind and high waves), an 
anthropogenic sound source would not be detectable as far away as would 
be possible under quieter conditions and would itself be masked. 
Ambient sound is highly variable on continental shelves (Thompson, 
1965; Myrberg, 1978; Chapman et al., 1998; Desharnais et al., 1999). 
This results in a high degree of variability in the range at which 
marine mammals can detect anthropogenic sounds.
    Although masking is a phenomenon which may occur naturally, the 
introduction of loud anthropogenic sounds into the marine environment 
at frequencies important to marine mammals increases the severity and 
frequency of occurrence of masking. For example, if a baleen whale is 
exposed to continuous low-frequency sound from an industrial source, 
this would reduce the size of the area around that whale within which 
it can hear the calls of another whale. The components of background 
noise that are similar in frequency to the signal in question primarily 
determine the degree of masking of that signal. In general, little is 
known about the degree to which marine mammals rely upon detection of 
sounds from conspecifics, predators, prey, or other natural sources. In 
the absence of specific information about the importance of detecting 
these natural sounds, it is not possible to predict the impact of 
masking on marine mammals (Richardson et al., 1995). In general, 
masking effects are expected to be less severe when sounds are 
transient than when they are continuous. Masking is typically of 
greater concern for those marine mammals that utilize low frequency 
communications, such as baleen whales and, as such, is not likely to 
occur for pinnipeds or small odontocetes in the Region of Activity.

Disturbance

    Behavioral disturbance is one of the primary potential impacts of 
anthropogenic sound on marine mammals. Disturbance can result in a 
variety of effects, such as subtle or dramatic changes in behavior or 
displacement, but the degree to which disturbance causes such effects 
may be highly dependent upon the context in which the stimulus occurs. 
For example, an animal that is feeding may be less prone to disturbance 
from a given stimulus than one that is not. For many species and 
situations, there is no detailed information about reactions to sound.
    Behavioral reactions of marine mammals to sound are difficult to 
predict because they are dependent on numerous factors, including 
species, maturity, experience, activity, reproductive state, time of 
day, and weather. If a marine mammal does react to an underwater sound 
by changing its behavior or moving a small distance, the impacts of 
that change may not be important to the individual, 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 the animals could be important. In general, pinnipeds seem 
more tolerant of, or at least habituate more quickly to, potentially 
disturbing underwater sound than do cetaceans, and generally seem to be 
less responsive to exposure to industrial sound than most cetaceans. 
Pinniped responses to underwater sound from some types of industrial 
activities such as seismic exploration appear to be temporary and 
localized (Harris et al., 2001; Reiser et al., 2009).
    Because the few available studies show wide variation in response 
to underwater and airborne sound, it is difficult to quantify exactly 
how pile driving sound would affect marine mammals in the area. The 
literature shows that elevated underwater sound levels could prompt a 
range of effects, including no obvious visible response, or behavioral 
responses that may include annoyance and increased alertness, visual 
orientation towards the sound, investigation of the sound, change in 
movement pattern or direction, habituation, alteration of feeding and 
social interaction, or temporary or permanent avoidance of the area 
affected by sound. Minor behavioral responses do not necessarily cause 
long-term effects to the individuals involved. Severe responses include 
panic, immediate movement away from the sound, and stampeding, which 
could potentially lead to injury or mortality (Southall et al., 2007).
    Southall et al. (2007) reviewed literature describing responses of 
pinnipeds to non-pulsed sound in water and reported that the limited 
data suggest exposures between approximately 90 and 140 dB generally do 
not appear to induce strong behavioral responses in pinnipeds, while 
higher levels of pulsed sound, ranging between 150 and 180 dB, will 
prompt avoidance of an area. It is important to note that among these 
studies, there are some apparent differences in responses between field 
and laboratory conditions. In contrast to the mid-frequency 
odontocetes, captive pinnipeds responded more strongly at lower levels 
than did animals in the field. Again, contextual issues are the likely 
cause of this difference. For airborne sound, Southall et al. (2007) 
note there are extremely limited data suggesting very minor, if any, 
observable behavioral responses by pinnipeds exposed to airborne pulses 
of 60 to 80 dB; however, given the paucity

[[Page 22110]]

of data on the subject, we cannot rule out the possibility that 
avoidance of sound in the Region of Activity could occur.
    In their comprehensive review of available literature, Southall et 
al. (2007) noted that quantitative studies on behavioral reactions of 
pinnipeds to underwater sound are rare. A subset of only three studies 
observed the response of pinnipeds to multiple pulses of underwater 
sound (a category of sound types that includes impact pile driving), 
and were also deemed by the authors as having results that are both 
measurable and representative. However, a number of studies not used by 
Southall et al. (2007) provide additional information, both 
quantitative and anecdotal, regarding the reactions of pinnipeds to 
multiple pulses of underwater sound.
    Harris et al. (2001) observed the response of ringed, bearded 
(Erignathus barbatus), and spotted seals (Phoca largha) to underwater 
operation of a single air gun and an eleven-gun array. Received 
exposure levels were 160 to 200 dB. Results fit into two categories. In 
some instances, seals exhibited no response to sound. However, the 
study noted significantly fewer seals during operation of the full 
array in some instances. Additionally, the study noted some avoidance 
of the area within 150 m of the source during full array operations.
    Blackwell et al. (2004) is the only cited study directly related to 
pile driving. The study observed ringed seals during impact 
installation of steel pipe pile. Received underwater SPLs were measured 
at 151 dB at 63 m. The seals exhibited either no response or only brief 
orientation response (defined as ``investigation or visual 
orientation''). It should be noted that the observations were made 
after pile driving was already in progress. Therefore, it is possible 
that the low-level response was due to prior habituation.
    Miller et al. (2005) observed responses of ringed and bearded seals 
to a seismic air gun array. Received underwater sound levels were 
estimated at 160 to 200 dB. There were fewer seals present close to the 
sound source during air gun operations in the first year, but in the 
second year the seals showed no avoidance. In some instances, seals 
were present in very close range of the sound. The authors concluded 
that there was ``no observable behavioral response'' to seismic air gun 
operations.
    During a Caltrans installation demonstration project for retrofit 
work on the East Span of the San Francisco Oakland Bay Bridge, 
California, sea lions responded to pile driving by swimming rapidly out 
of the area, regardless of the size of the pile-driving hammer or the 
presence of sound attenuation devices (74 FR 63724).
    Jacobs and Terhune (2002) observed harbor seal reactions to 
acoustic harassment devices (AHDs) with source level of 172 dB deployed 
around aquaculture sites. Seals were generally unresponsive to sounds 
from the AHDs. During two specific events, individuals came within 141 
and 144 ft (43 and 44 m) of active AHDs and failed to demonstrate any 
measurable behavioral response; estimated received levels based on the 
measures given were approximately 120 to 130 dB.
    Costa et al. (2003) measured received sound levels from an Acoustic 
Thermometry of Ocean Climate (ATOC) program sound source off northern 
California using acoustic data loggers placed on translocated elephant 
seals. Subjects were captured on land, transported to sea, instrumented 
with archival acoustic tags, and released such that their transit would 
lead them near an active ATOC source (at 0.6 mi depth [939 m]; 75-Hz 
signal with 37.5-Hz bandwidth; 195 dB maximum source level, ramped up 
from 165 dB over 20 min) on their return to a haul-out site. Received 
exposure levels of the ATOC source for experimental subjects averaged 
128 dB (range 118 to 137) in the 60- to 90-Hz band. None of the 
instrumented animals terminated dives or radically altered behavior 
upon exposure, but some statistically significant changes in diving 
parameters were documented in nine individuals. Translocated northern 
elephant seals exposed to this particular non-pulse source began to 
demonstrate subtle behavioral changes at exposure to received levels of 
approximately 120 to 140 dB.
    Several available studies provide information on the reactions of 
pinnipeds to non-pulsed underwater sound. Kastelein et al. (2006) 
exposed nine captive harbor seals in an approximately 82 x 98 ft (25 x 
30 m) enclosure to non-pulse sounds used in underwater data 
communication systems (similar to acoustic modems). Test signals were 
frequency modulated tones, sweeps, and bands of sound with fundamental 
frequencies between 8 and 16 kHz; 128 to 130 3 dB source 
levels; 1- to 2-s duration (60-80 percent duty cycle); or 100 percent 
duty cycle. They recorded seal positions and the mean number of 
individual surfacing behaviors during control periods (no exposure), 
before exposure, and in 15-min experimental sessions (n = 7 exposures 
for each sound type). Seals generally swam away from each source at 
received levels of approximately 107 dB, avoiding it by approximately 
16 ft (5 m), although they did not haul out of the water or change 
surfacing behavior. Seal reactions did not appear to wane over repeated 
exposure (i.e., there was no obvious habituation), and the colony of 
seals generally returned to baseline conditions following exposure. The 
seals were not reinforced with food for remaining in the sound field.
    Reactions of harbor seals to the simulated sound of a 2-megawatt 
wind power generator were measured by Koschinski et al. (2003). Harbor 
seals surfaced significantly further away from the sound source when it 
was active and did not approach the sound source as closely. The device 
used in that study produced sounds in the frequency range of 30 to 800 
Hz, with peak source levels of 128 dB at 1 m at the 80- and 160-Hz 
frequencies.
    Ship and boat sound do not seem to have strong effects on seals in 
the water, but the data are limited. When in the water, seals appear to 
be much less apprehensive about approaching vessels. Some would 
approach a vessel out of apparent curiosity, including noisy vessels 
such as those operating seismic airgun arrays (Moulton and Lawson, 
2002). Gray seals (Halichoerus grypus) have been known to approach and 
follow fishing vessels in an effort to steal catch or the bait from 
traps. In contrast, seals hauled out on land often are quite responsive 
to nearby vessels. Terhune (1985) reported that northwest Atlantic 
harbor seals were extremely vigilant when hauled out and were wary of 
approaching (but less so passing) boats. Suryan and Harvey (1999) 
reported that Pacific harbor seals commonly left the shore when 
powerboat operators approached to observe the seals. Those seals 
detected a powerboat at a mean distance of 866 ft (264 m), and seals 
left the haul-out site when boats approached to within 472 ft (144 m).
    The studies that address responses of high-frequency cetaceans 
(such as the harbor porpoise) to non-pulse sounds include data gathered 
both in the field and the laboratory and related to several different 
sound sources (of varying similarity to chirps), including: Pingers, 
AHDs, and various laboratory non-pulse sounds. All of these data were 
collected from harbor porpoises. Southall et al. (2007) concluded that 
the existing data indicate that harbor porpoises are likely sensitive 
to a wide range of anthropogenic sounds at low received levels (around 
90 to 120 dB), at least for initial exposures. All recorded exposures 
above 140 dB induced profound and sustained avoidance behavior in wild 
harbor porpoises

[[Page 22111]]

(Southall et al., 2007). Rapid habituation was noted in some but not 
all studies. Data on behavioral responses of high-frequency cetaceans 
to multiple pulses is not available. Although individual elements of 
some non-pulse sources (such as pingers) could be considered pulses, it 
is believed that some mammalian auditory systems perceive them as non-
pulse sounds (Southall et al., 2007).
    Southall et al. (2007) also compiled known studies of behavioral 
responses of marine mammals to airborne sound, noting that studies of 
pinniped response to airborne pulsed sounds are exceedingly rare. The 
authors deemed only one study as having quantifiable results. Blackwell 
et al. (2004) studied the response of ringed seals within 500 m of 
impact driving of steel pipe pile. Received levels of airborne sound 
were measured at 93 dB at a distance of 63 m. Seals had either no 
response or limited response to pile driving. Reactions were described 
as ``indifferent'' or ``curious.''
    Marine mammals are expected to traverse through and not remain in 
the project area. Therefore, animals are not expected to be exposed to 
a significant duration of construction sound.
    Vessel Operations--A work/equipment barge and small range craft 
would be present in the Region of Activity at various times due to 
construction activities. The small range craft vessel would travel at 
low speeds and would be used to monitor for marine mammals in the area. 
Such vessels already use the Region of Activity in moderately high 
numbers; therefore, the vessels to be used in the Region of Activity do 
not represent a new sound source, only a potential increase in the 
frequency and duration of these sound source types.
    There are very few controlled tests or repeatable observations 
related to the reactions of marine mammals to vessel noise. However, 
Richardson et al. (1995) reviewed the literature on reactions of marine 
mammals to vessels, concluding overall that pinnipeds and many 
odontocetes showed high tolerance to vessel noise. Mysticetes, too, 
often show tolerance of slow, quieter vessels. Because the Region of 
Activity is highly industrialized, it seems likely that marine mammals 
that transit the Region of Activity are already habituated to vessel 
noise, thus the additional vessels that would occur as a result of 
construction activities would likely not have an additional effect on 
these animals. Vessels occurring as a result of construction activities 
would be mostly stationary or moving slowly for marine mammal 
monitoring. Therefore, proposed vessel noise and operations in the 
Region of Activity is unlikely to rise to the level of harassment.
    Physical Disturbance--Vessels and in-water structures have the 
potential to cause physical disturbance to marine mammals. As 
previously mentioned, various types of vessels already use the Region 
of Activity in high numbers. Tug boats and barges are slow moving and 
follow a predictable course. Marine mammals would be able to easily 
avoid these vessels while transiting through the Region of Activity and 
are likely already habituated to the presence of numerous vessels. 
Therefore, vessel strikes are extremely unlikely and, thus, 
discountable. Potential encounters would likely be limited to brief, 
sporadic behavioral disturbance, if any at all. Such disturbances are 
not likely to result in a risk of Level B harassment of marine mammals 
transiting the Region of Activity.

Hearing Impairment and Other Physiological Effects

    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds. Non-auditory 
physiological effects might also occur in marine mammals exposed to 
strong underwater sound. Possible types of non-auditory physiological 
effects or injuries that may occur in mammals close to a strong sound 
source include stress, neurological effects, bubble formation, and 
other types of organ or tissue damage. It is possible that some marine 
mammal species (i.e., beaked whales) may be especially susceptible to 
injury and/or stranding when exposed to strong pulsed sounds, 
particularly at higher frequencies. Non-auditory physiological effects 
are not anticipated to occur as a result of proposed construction 
activities. The following subsections discuss the possibilities of TTS 
and PTS.
    TTS--TTS, reversible hearing loss caused by fatigue of hair cells 
and supporting structures in the inner ear, 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. TTS can last from 
minutes or hours to (in cases of strong TTS) days. 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.
    Marine mammal hearing plays a critical role in communication with 
conspecifics and in interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that takes place during a time when the animal is traveling 
through the open ocean, where ambient noise is lower and there are not 
as many competing sounds present. Alternatively, a larger amount and 
longer duration of TTS sustained during a time when communication is 
critical for successful mother/calf interactions could have more 
serious impacts if it were in the same frequency band as the necessary 
vocalizations and of a severity that it impeded communication. The fact 
that animals exposed to levels and durations of sound that would be 
expected to result in this physiological response would also be 
expected to have behavioral responses of a comparatively more severe or 
sustained nature is also notable and potentially of more importance 
than the simple existence of a TTS.
    NMFS considers TTS to be a form of Level B harassment, as it 
consists of fatigue to auditory structures rather than damage to them. 
The NMFS-established 190-dB criterion is not considered to be the level 
above which TTS might occur. Rather, it is the received level above 
which, in the view of a panel of bioacoustics specialists convened by 
NMFS before TTS measurements for marine mammals became available, one 
could not be certain that there would be no injurious effects, auditory 
or otherwise, to marine mammals. Therefore, exposure to sound levels 
above 180 and 190 dB (for cetaceans and pinnipeds, respectively) does 
not necessarily mean that an animal has incurred TTS, but rather that 
it may have occurred. 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.
    Human non-impulsive sound exposure guidelines are based on 
exposures of equal energy (the same sound exposure level [SEL]; SEL is 
reported here in dB re: 1 [micro]Pa\2\-s/re: 20 [micro]Pa\2\-s for in-
water and in-air sound, respectively) producing equal amounts of 
hearing impairment regardless of how the sound energy is distributed in 
time (NIOSH, 1998). Until recently, previous marine mammal TTS studies 
have also

[[Page 22112]]

generally supported this equal energy relationship (Southall et al., 
2007). Three newer studies, two by Mooney et al. (2009a, b) on a single 
bottlenose dolphin (Tursiops truncatus) either exposed to playbacks of 
U.S. Navy mid-frequency active sonar or octave-band sound (4-8 kHz) and 
one by Kastak et al. (2007) on a single California sea lion exposed to 
airborne octave-band sound (centered at 2.5 kHz), concluded that for 
all sound exposure situations, the equal energy relationship may not be 
the best indicator to predict TTS onset levels. Generally, with sound 
exposures of equal energy, those that were quieter (lower SPL) with 
longer duration were found to induce TTS onset more than those of 
louder (higher SPL) and shorter duration. Given the available data, the 
received level of a single seismic pulse (with no frequency weighting) 
might need to be approximately 186 dB SEL in order to produce brief, 
mild TTS.
    In free-ranging pinnipeds, TTS thresholds associated with exposure 
to brief pulses (single or multiple) of underwater sound have not been 
measured. However, systematic TTS studies on captive pinnipeds have 
been conducted (e.g., Bowles et al., 1999; Kastak et al., 1999, 2005, 
2007; Schusterman et al., 2000; Finneran et al., 2003; Southall et al., 
2007). Specific studies are detailed here: Finneran et al. (2003) 
studied responses of two individual California sea lions. The sea lions 
were exposed to single pulses of underwater sound, and experienced no 
detectable TTS at received sound level of 183 dB peak (163 dB SEL). 
There were three studies conducted on pinniped TTS responses to non-
pulsed underwater sound. All of these studies were performed in the 
same lab and on the same test subjects, and, therefore, the results may 
not be applicable to all pinnipeds or in field settings. Kastak and 
Schusterman (1996) studied the response of harbor seals to non-pulsed 
construction sound, reporting TTS of about 8 dB. The seal was exposed 
to broadband construction sound for 6 days, averaging 6 to 7 hours of 
intermittent exposure per day, with SPLs from just approximately 90 to 
105 dB.
    Kastak et al. (1999) reported TTS of approximately 4-5 dB in three 
species of pinnipeds (harbor seal, California sea lion, and northern 
elephant seal) after underwater exposure for approximately 20 minutes 
to sound with frequencies ranging from 100-2,000 Hz at received levels 
60-75 dB above hearing threshold. This approach allowed similar 
effective exposure conditions to each of the subjects, but resulted in 
variable absolute exposure values depending on subject and test 
frequency. Recovery to near baseline levels was reported within 24 
hours of sound exposure. Kastak et al. (2005) followed up on their 
previous work, exposing the same test subjects to higher levels of 
sound for longer durations. The animals were exposed to octave-band 
sound for up to 50 minutes of net exposure. The study reported that the 
harbor seal experienced TTS of 6 dB after a 25-minute exposure to 2.5 
kHz of octave-band sound at 152 dB (183 dB SEL). The California sea 
lion demonstrated onset of TTS after exposure to 174 dB and 206 dB SEL.
    Southall et al. (2007) reported one study on TTS in pinnipeds 
resulting from airborne pulsed sound, while two studies examined TTS in 
pinnipeds resulting from airborne non-pulsed sound. Bowles et al. 
(unpubl. data) exposed pinnipeds to simulated sonic booms. Harbor seals 
demonstrated TTS at 143 dB peak and 129 dB SEL. California sea lions 
and northern elephant seals experienced TTS at higher exposure levels 
than the harbor seals. Kastak et al. (2004) used the same test subjects 
as in Kastak et al. 2005, exposing the animals to non-pulsed sound (2.5 
kHz octave-band sound) for 25 minutes. The harbor seal demonstrated 6 
dB of TTS after exposure to 99 dB (131 dB SEL). The California sea lion 
demonstrated onset of TTS at 122 dB and 154 dB SEL. Kastak et al. 
(2007) studied the same California sea lion as in Kastak et al. 2004 
above, exposing this individual to 192 exposures of 2.5 kHz octave-band 
sound at levels ranging from 94 to 133 dB for 1.5 to 50 min of net 
exposure duration. The test subject experienced up to 30 dB of TTS. TTS 
onset occurred at 159 dB SEL. Recovery times ranged from several 
minutes to 3 days.
    Additional studies highlight the inherent complexity of predicting 
TTS onset in marine mammals, as well as the importance of considering 
exposure duration when assessing potential impacts (Mooney et al., 
2009a, 2009b; Kastak et al., 2007). Generally, with sound exposures of 
equal energy, quieter sounds (lower SPL) of longer duration were found 
to induce TTS onset more than louder sounds (higher SPL) of shorter 
duration (more similar to subbottom profilers). For intermittent 
sounds, less threshold shift will occur than from a continuous exposure 
with the same energy (some recovery will occur between intermittent 
exposures) (Kryter et al., 1966; Ward, 1997). For sound exposures at or 
somewhat above the TTS-onset threshold, hearing sensitivity recovers 
rapidly after exposure to the sound ends. Southall et al. (2007) 
considers a 6 dB TTS (that is, baseline thresholds are elevated by 6 
dB) to be a sufficient definition of TTS-onset. NMFS considers TTS as 
Level B harassment that is mediated by physiological effects on the 
auditory system; however, NMFS does not consider TTS-onset to be the 
lowest level at which Level B harassment may occur. Southall et al. 
(2007) summarizes underwater pinniped data from Kastak et al. (2005), 
indicating that a tested harbor seal showed a TTS of around 6 dB when 
exposed to a nonpulse noise at sound pressure level 152 dB re: 1 
[micro]Pa for 25 minutes.
    Some studies suggest that harbor porpoises may be more sensitive to 
sound than other odontocetes (Lucke et al., 2009; Kastelein et al., 
2011). While TTS onset may occur in harbor porpoises at lower received 
levels (when compared to other odontocetes), NMFS' 160-dB and 120-dB 
threshold criteria are based on the onset of behavioral harassment, not 
the onset of TTS. The potential for TTS is considered within NMFS' 
analysis of potential impacts from Level B harassment.
    Impact pile driving for the Elliott Bay Seawall project would 
produce initial airborne sound levels of approximately 112 dB peak at 
160 ft (49 m) from the source, as compared to the level suggested by 
Southall et al. (2007) of 143 dB peak for onset of TTS in pinnipeds 
from multiple pulses of airborne sound. It is not expected that 
airborne sound levels would induce TTS in individual pinnipeds.
    Although underwater sound levels produced by the proposed project 
may exceed levels produced in studies that have induced TTS in marine 
mammals, there is a general lack of controlled, quantifiable field 
studies related to this phenomenon, and existing studies have had 
varied results (Southall et al., 2007). Therefore, it is difficult to 
extrapolate from these data to site-specific conditions for the 
proposed project. For example, because most of the studies have been 
conducted in laboratories, rather than in field settings, the data are 
not conclusive as to whether elevated levels of sound would cause 
marine mammals to avoid the Region of Activity, thereby reducing the 
likelihood of TTS, or whether sound would attract marine mammals, 
increasing the likelihood of TTS. In any case, there are no universally 
accepted standards for the amount of exposure time likely to induce 
TTS. While it may be inferred that TTS could theoretically result from 
the proposed project, it is impossible to quantify the magnitude of 
exposure, the duration of the effect, or

[[Page 22113]]

the number of individuals likely to be affected. Exposure is likely to 
be brief because marine mammals use the Region of Activity for 
transiting, rather than breeding or hauling out. In summary, it is 
expected that elevated sound would have only a slight probability of 
causing TTS in marine mammals.
    PTS--When PTS occurs, there is physical damage to the sound 
receptors in the ear. In some cases, there can be total or partial 
deafness, whereas in other cases, the animal has an impaired ability to 
hear sounds in specific frequency ranges. There is no specific evidence 
that exposure to underwater industrial sounds can cause PTS in any 
marine mammal (see Southall et al., 2007). However, given the 
possibility that marine mammals might incur TTS, there has been further 
speculation about the possibility that some individuals occurring very 
close to industrial activities might incur PTS. Richardson et al. 
(1995) hypothesized that PTS caused by prolonged exposure to continuous 
anthropogenic sound is unlikely to occur in marine mammals, at least 
for sounds with source levels up to approximately 200 dB. Single or 
occasional occurrences of mild TTS are not indicative of permanent 
auditory damage in terrestrial mammals. Studies of relationships 
between TTS and PTS thresholds in marine mammals are limited; however, 
existing data appear to show similarity to those found for humans and 
other terrestrial mammals, for which there is a large body of data. PTS 
might occur at a received sound level at least several decibels above 
that inducing mild TTS.
    Southall et al. (2007) propose that sound levels inducing 40 dB of 
TTS may result in onset of PTS in marine mammals. The authors present 
this threshold with precaution, as there are no specific studies to 
support it. Because direct studies on marine mammals are lacking, the 
authors base these recommendations on studies performed on other 
mammals. Additionally, the authors assume that multiple pulses of 
underwater sound result in the onset of PTS in pinnipeds when levels 
reach 218 dB peak or 186 dB SEL. In air, sound levels are assumed to 
cause PTS in pinnipeds at 149 dB peak or 144 dB SEL (Southall et al., 
2007). Sound levels this high are not expected to occur as a result of 
the proposed activities.
    The potential effects to marine mammals described in this section 
of the document do not take into consideration the proposed monitoring 
and mitigation measures described later in this document (see the 
Proposed Mitigation and Proposed Monitoring and Reporting sections). It 
is highly unlikely that marine mammals would receive sounds strong 
enough (and over a sufficient duration) to cause PTS (or even TTS) 
during the proposed activities. When taking the mitigation measures 
proposed for inclusion in the regulations into consideration, it is 
highly unlikely that any type of hearing impairment would occur as a 
result of SDOT's proposed activities.

Anticipated Effects on Marine Mammal Habitat

    Construction activities would likely impact general marine mammal 
habitat and Southern resident killer whale critical habitat (designated 
throughout the Puget Sound region) in Elliott Bay and adjacent Puget 
Sound by producing temporary disturbances, primarily through elevated 
levels of underwater sound, reduced water quality, and physical habitat 
alteration associated with the structural footprint of the new seawall. 
Another potential temporary effect would be changes in prey species 
distribution during construction. However, overall, the proposed 
activity is expected to improve marine mammal habitat. Furthermore, 
sound levels constituting Level B harassment would not extend 
completely across Puget Sound, allowing marine mammals to avoid the 
higher levels of sound in Elliott Bay. Negative long-term effects are 
not anticipated.
    A large portion of the Elliott Bay Seawall project is proposed 
habitat enhancement in the nearshore, which includes improving the 
quality of substrate, adding riparian plantings, burying contaminated 
sediment, and adding light-penetrating surfaces to overwater structures 
to enhance shallow water habitats for salmonid migration. In-water work 
during this part of the project may temporarily disturb marine mammals 
from general equipment/barge noise and temporarily increased turbidity. 
However, in the long-term, these habitat enhancements would likely 
benefit marine mammals indirectly as they are designed to increase 
habitat quality for prey species such as salmonids and marine 
invertebrates.
    Marine mammals are especially vulnerable to contaminants because 
they are high up in the trophic level and may experience 
bioaccumulations. Water quality would generally improve as a result of 
the construction of stormwater treatment facilities associated with the 
Elliott Bay Seawall project. Currently, stormwater from the project 
area is discharged into Elliott Bay untreated. After completion of the 
proposed project, stormwater leaving the project area would receive 
treatment to remove suspended sediments and any pollutants bound to 
sediment. Analysis of post-project stormwater plumes conducted for the 
Endangered Species Act (ESA) analysis indicates that pollutants of 
concern to fish species will dilute to background concentrations 
generally within five feet of the outfalls; thus stormwater would have 
inconsequential effects on marine mammal prey species. The installation 
of the habitat features would generally bury up to two acres of low to 
moderately contaminated sediments and reduce the potential exposure of 
marine invertebrates and salmonids to contaminants and the potential 
for bioaccumulation up the food chain to marine mammals.
    The underwater sounds would occur as short-term pulses (i.e., 
minutes to hours), separated by virtually instantaneous and complete 
recovery periods. These disturbances are likely to occur several times 
a day for up to a week, less than 1 week per year, for up to 7 years (5 
years of activity would be authorized under this rule). Physical 
habitat alteration due to modification and replacement of existing in-
water and over-water structures would also occur intermittently during 
construction, and would remain as the final, as-built project footprint 
for the design life of the Elliott Bay Seawall.
    Elevated levels of sound may be considered to affect the in-water 
habitat of marine mammals via impacts to prey species or through 
passage obstruction (discussed later). However, due to the timing of 
the in-water work and the limited amount of pile driving that may occur 
on a daily basis, these effects on marine mammal habitat would be 
temporary and limited in duration. Any marine mammals that encounter 
increased sound levels would primarily be transiting the action area 
and foraging opportunistically. The direct loss of habitat available 
during construction due to sound impacts is expected to be minimal.

Impacts to Prey Species

    Prey species for the various marine mammals that may occur in the 
proposed project area include marine invertebrates and fish. Short-term 
effects would occur to marine invertebrates immediately along the 
existing seawall during construction. The installation of the temporary 
containment wall would necessitate the removal of riprap that hosts 
various invertebrate and macroalgae species, and invertebrates present 
behind the temporary containment wall could experience

[[Page 22114]]

mortality or decreased growth during the first season of construction 
occurring at each location. This effect is expected to be minor and 
short-term on the overall population of marine invertebrates in Elliott 
Bay. Construction would also have temporary effects on salmonids and 
other fish species in the project area due to disturbance, turbidity, 
noise, and the potential resuspension of contaminants.
    Impact pile driving would produce a variety of underwater sound 
levels. Underwater sound caused by vibratory installation would be less 
than impact driving (Caltrans, 2009; WSDOT, 2010b). Literature relating 
to the impacts of sound on marine fish species can be divided into 
categories which describe the following: (1) Pathological effects; (2) 
physiological effects; and (3) behavioral effects. Pathological effects 
include lethal and sub-lethal physical damage to fish; physiological 
effects include primary and secondary stress responses; and behavioral 
effects include changes in exhibited behaviors of fish. Behavioral 
changes might be a direct reaction to a detected sound or a result of 
anthropogenic sound masking natural sounds that the fish normally 
detect and to which they respond. The three types of effects are often 
interrelated in complex ways. For example, some physiological and 
behavioral effects could potentially lead ultimately to the 
pathological effect of mortality. Hastings and Popper (2005) reviewed 
what is known about the effects of sound on fish and identified studies 
needed to address areas of uncertainty relative to measurement of sound 
and the responses of fish. Popper et al. (2003/2004) also published a 
paper that reviews the effects of anthropogenic sound on the behavior 
and physiology of fish. Please see those sources for more detail on the 
potential impacts of sound on fish.
    Underwater sound pressure waves can injure or kill fish (e.g., 
Reyff, 2003; Abbott and Bing-Sawyer, 2002; Caltrans, 2001; Longmuir and 
Lively, 2001; Stotz and Colby, 2001). Fish with swim bladders, 
including salmon, steelhead, and sturgeon, are particularly sensitive 
to underwater impulsive sounds with a sharp sound pressure peak 
occurring in a short interval of time (Caltrans, 2001). As the pressure 
wave passes through a fish, the swim bladder is rapidly squeezed due to 
the high pressure, and then rapidly expanded as the underpressure 
component of the wave passes through the fish. The pneumatic pounding 
may rupture capillaries in the internal organs as indicated by observed 
blood in the abdominal cavity and maceration of the kidney tissues 
(Caltrans, 2001). Although eulachon lack a swim bladder, they are also 
susceptible to general pressure wave injuries including hemorrhage and 
rupture of internal organs, as described above, and damage to the 
auditory system. Direct take can cause instantaneous death, latent 
death within minutes after exposure, or can occur several days later. 
Indirect take can occur because of reduced fitness of a fish, making it 
susceptible to predation, disease, starvation, or inability to complete 
its life cycle.
    All in-water work would occur during the designated in-water work 
window to avoid and minimize effects on juvenile salmonids. 
Additionally, marine resident fish species are only present in limited 
numbers along the seawall during the work season and primarily occur 
during the summer months when work would not be occurring. Prey species 
are expected to incur a long-term benefit from the proposed habitat 
enhancements; these enhancements would improve primary and secondary 
productivity and migratory habitat for salmonids.

Proposed Mitigation

    In order to issue an incidental take authorization under section 
101(a)(5)(A) of the MMPA, NMFS must, where applicable, set forth the 
permissible methods of taking pursuant to such activity, and other 
means of effecting the least practicable adverse impact on such species 
or stock and their 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). NMFS and SDOT worked to devise a 
number of mitigation measures designed to minimize impacts to marine 
mammals to the level of least practicable adverse impact.

Limited Impact Pile Driving

    All sheet piles would be installed using a vibratory driver, unless 
impact driving is required to install piles that encounter consolidated 
sediments or for proofing load bearing sections. The use of vibratory 
pile driving reduces pile driving noise to levels less than the injury 
threshold for marine mammals. Any impact driving used in conjunction 
with vibratory pile driving would employ attenuation measures such as a 
cushioning block, where applicable. Any attenuation measures that 
become available for vibratory pile driving would also be considered 
for the proposed project.

Containment of Impact Pile Driving

    The majority of permanent concrete piles would be driven behind the 
temporary containment wall that would function as a physical barrier to 
partially attenuate pile driving noise. Estimated noise-reduction 
values are not readily available for this attenuation type; however, it 
has been shown that the use of cofferdams, which are analogous to the 
temporary containment wall, is effective at reducing noise up to 10 dB 
(Caltrans, 2009).

Additional Attenuation Measures

    Other attenuation measures such as bubble curtains may be employed 
as necessary to reduce sound levels. While bubble curtains were 
considered, they are not being proposed due to the potential for 
resuspension of contaminated materials and/or existing sediment caps; 
however, in some locations they could be feasible for the concrete pile 
driving and would be considered if sound levels are measured higher 
than what is shown in this analysis. In the event that underwater sound 
monitoring shows that noise generation from pile installation exceeds 
the levels originally expected, the implementation of additional 
attenuation devices would be reevaluated and discussed with NMFS.

Ramp-up

    The objective of a ramp-up is to alert any animals close to the 
activity and allow them time to move away, which would expose fewer 
animals to loud sounds, including both underwater and above water 
sound. This procedure also ensures that any animals missed during 
monitoring within the exclusion zone would have the opportunity to move 
away from the activity and avoid injury. During all in-water pile-
related activities, ramp-up would be used at the beginning of each 
day's in-water pile-related activities or if pile driving has ceased 
for more than 1 hour. If a vibratory driver is used, contractors would 
be required to initiate sound from vibratory hammers for 15 seconds at 
reduced energy followed by a 1-minute waiting period. The procedure 
would be repeated two additional times before full energy may be 
achieved. If a non-diesel impact hammer is used, contractors would be 
required to provide an initial set of strikes from the impact hammer at 
reduced energy, followed by a 1-minute waiting period, then two 
subsequent sets. The reduced energy of an individual hammer cannot be 
quantified because they vary by individual drivers. Also, the number of 
strikes would vary at reduced energy

[[Page 22115]]

because raising the hammer at less than full power and then releasing 
it results in the hammer `bouncing' as it strikes the pile, resulting 
in multiple strikes.

Marine Mammal Exclusion Zones

    For this proposed project, the purpose of an exclusion zone is to 
prevent Level A harassment of all marine mammals and to reduce take of 
large whales from Level B harassment. SDOT would establish different 
exclusion zones for different types of in-water pile-related 
activities:
    1. An exclusion zone for pinnipeds and small cetaceans with a 
radius of 200 ft waterward of each steel sheet pile source during 
impact pile driving;
    2. An exclusion zone for pinnipeds and small cetaceans with a 
radius of 50 ft waterward of each concrete piling point source during 
impact pile driving;
    3. An exclusion zone for large whales with a radius of 1,000 m 
(3,280 ft) waterward of each steel sheet or concrete pile during impact 
pile driving; and
    4. An exclusion zone for large whales with a radius of 3,981 m (2.5 
miles) waterward of each steel sheet pile source during vibratory pile 
driving.
    The last two exclusion zones were recommended by NMFS to prevent 
the take of large whales by Level A harassment and reduce the take of 
large whales by Level B harassment. While the 3,981 m (2.5 mile) 
exclusion zone does not extend to the Level B harassment ispoleth for 
vibratory pile driving (6,276 m [3.9 miles]), it does cover a majority 
of the radius and allows for protected species observers to easily 
monitor the entrance of Elliott Bay from land. Temporary buoys would be 
used, as feasible, to mark the distance to the exclusion zones. These 
zones are intended to provide a physical threshold for a stop-work 
order for in-water pile-related activities if a marine mammal nears the 
proposed work area. At the start of in-water pile-related construction 
each day, a minimum of one qualified protected species observer would 
be staged on land (or an adjacent pier) near the location of in-water 
activities to document any marine mammal that approaches the exclusion 
zones. Additional land-based observers would be deployed if needed to 
ensure the construction area is adequately monitored. Land-based 
monitoring would occur throughout each day of active pile-related 
activities.
    If a marine mammal is sighted approaching the work area, protected 
species observers would immediately notify the construction personnel 
operating the pile-related equipment of the direction of travel and 
distance relative to the exclusion zones. SDOT initially proposed that 
in-water pile-related stop-work order would be immediately triggered if 
a cetacean approaches or enters an exclusion zone or if an observer 
documents a pinniped displaying clear signs of stress or distress, such 
as difficulty swimming, breathing, or other disoriented behaviors. 
However, based on NMFS recommendation, a stop-work order would be 
triggered if any marine mammal enters an exclusion zone, regardless of 
observed behavior. SDOT's proposed exclusion zones would minimize 
injurious impacts to all marine mammals from increased sound exposures 
and would prevent take of large whales. The exclusion zones must not be 
obscured by fog or poor lighting conditions in order for in-water pile-
related activities to begin/continue.

Shutdown and Delay Procedures

    If a marine mammal is seen approaching or entering an exclusion 
zone, observers would immediately notify the construction personnel 
operating the pile-related equipment to shutdown pile-related 
activities. If a marine mammal(s) is present within the applicable 
exclusion zone prior to in-water pile-related activities, pile driving/
removal would be delayed until the animal(s) has left the exclusion 
zone or until 15 minutes have elapsed without observing the animal.

Conclusions

    NMFS has carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that NMFS prescribes the means of effecting the least 
practicable adverse 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:
     The manner in which, and the degree to which, the 
successful implementation of the measure is expected to minimize 
adverse impacts to marine mammals;
     The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
     The practicability of the measure for applicant 
implementation.
    Based on our evaluation, NMFS has preliminarily determined that the 
proposed mitigation measures provide the means of effecting the least 
practicable adverse impact on marine mammal species or stocks and their 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance. The proposed rule comment period will 
afford the public an opportunity to submit recommendations, views, and/
or concerns regarding this action and the proposed mitigation measures.

Proposed Monitoring and Reporting

    In order to issue an incidental take authorization for an activity, 
section 101(a)(5)(A) of the MMPA states that NMFS must set forth, where 
applicable, ``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 incidental take authorizations must 
include the suggested means of accomplishing the necessary monitoring 
and reporting that will result in increased knowledge of the species 
and of the level of taking or impacts on populations of marine mammals 
that are expected to be present in the proposed action area.

Visual Monitoring

    In addition to the mitigation monitoring described in the Marine 
Mammal Exclusion Zones section above, a minimum of two protected 
species observers would be positioned on land at the north and sound 
ends of Elliott Bay near the 2.5 mile exclusion zone to monitor for 
marine mammals during vibratory pile-related activities or any other 
construction activities that may pose a threat to marine mammals moving 
through the area. These observers would have no other responsibilities 
while on station. Observers would also be responsible for recording the 
location of all marine mammal sightings and logging information onto 
marine mammal sighting forms. Observers would use the naked eye, wide-
angle binoculars with reticles, and spotting scopes to scan the area 
around their station. SDOT proposes to employ this monitoring every day 
during which vibratory pile driving occurs.
    Each observer would work a maximum of 8 hours per day and would be 
relieved by a fresh observer if pile driving occurs over a longer day 
(i.e., 12 or 16 hours). The number of observers would be increased and/
or positions changed to ensure full visibility of the area. All 
monitoring would begin at least 30 minutes prior to the start of in-
water pile-related activities and continue during active construction. 
At a minimum, observers would record the following information:
     Date of observation period, monitoring type (land-based/
boat-based), observer name and location,

[[Page 22116]]

climate and weather conditions, and tidal conditions;
     Environmental conditions that could confound marine mammal 
detections and when/where they occurred;
     For each marine mammal sighting, the time of initial 
sighting and duration to the end of the sighting period;
     Observed species, number, group composition, distance to 
pile-related activities, and behavior of animals throughout the 
sighting;
     Discrete behavioral reactions, if apparent;
     Initial and final sighting locations marked on a grid map;
     Pile-related activities taking place during each sighting 
and if/why a shutdown was or was not triggered; and
     The number of takes (by species) of marine mammals, their 
locations, and behavior.

Acoustic Monitoring

    SDOT would conduct acoustic monitoring during pile-related in-water 
work. The purpose of this monitoring would be to identify or confirm 
noise levels for pile-related work during in-water construction. 
Collection of acoustic data would be accomplished from both a drifting 
boat to reduce the effect of flow noise, and attached on or adjacent to 
piers located at 10 m from the pile source. All acoustical recordings 
would be conducted 1 m below the water surface and 1 m above the sea 
floor. Background noise recordings (in the absence of pile driving) 
would also be made to provide a baseline background noise profile. The 
results and conclusions of the study would be summarized and presented 
to NMFS with recommendations for any modifications to the monitoring 
plan or exclusion zones.
    Underwater hydrophones and an airborne microphone would be used for 
acoustic recordings. All sensors, signal conditioning equipment, and 
sampling equipment would be calibrated at the start of the monitoring 
period and rechecked at the start of each day. A stationary two-channel 
hydrophone recording system would be deployed to record a 
representative sample (subset of piles) during the monitoring period. 
Prior to monitoring, water depth measurements would be taken to ensure 
that hydrophones do not drag on the bottom during tidal changes. One 
hydrophone would be placed at mid-depth and the other would be placed 
closer to the bottom (70 to 85 percent of the water depth). The depth 
with respect to the bottom may vary due to tidal changes and current 
effects since the hydrophones may be supported from a floating 
platform.
    Appropriate measures would be taken to eliminate strumming of the 
hydroacoustic cable in the current and minimize flow noise over the 
hydrophones. There would be a direct line of acoustic transmission 
through the water column between the pile and the hydrophones in all 
cases, without any interposing structures, including other piles. At 
least one stationary land-based microphone would be deployed to record 
airborne sound levels produced during pile installation and removal. 
The microphone would measure far-field airborne sounds. A sound level 
meter with microphone would be located in the near-field if logistical 
and security constraints allow for the collection of near-field source 
level measurements. Near-field measurements would not be continuous and 
would be used to identify which sound sources are making significant 
contributions to the overall noise levels measured at the shoreline 
microphones. Specific locations would be determined by ease of access 
(terrain restrictions and presence of a road) and security permission. 
The microphone will be calibrated at the beginning of each day of 
monitoring activity.
    To empirically verify the modeled behavioral disturbance zones, 
underwater and airborne acoustic monitoring would occur for the first 
five steel sheet pile and the first five concrete piles during the 
duration of pile driving. If a representative sample has not been 
achieved after the five piles have been monitored (e.g., if there is 
high variability of sound levels between pilings), acoustic monitoring 
would continue until a representative acoustic sample has been 
collected. Post-analysis of underwater sound level signals would 
include the following:
     RMS values (average, standard deviation/error, minimum, 
and maximum) for each recorded pile. The 10-second RMS averaged values 
will be used for determining the source value and extent of the 120 dB 
underwater isopleth;
     Frequency spectra for each functional hearing group; and
     Standardized underwater source levels to a reference 
distance of 10 m (33 ft).

Post-analysis of airborne noise would be presented in an unweighted 
format and include:
     The unweighted RMS values (average, minimum, and maximum) 
for each recorded pile. The average values would be used for 
determining the extent of the airborne isopleths relative to species-
specific criteria;
     Frequency spectra from 10 Hz to 20 kHz for representative 
pile-related activity; and
     Standardized airborne source levels to a reference 
distance of approximately 15 m (50 ft).
    It is intended that acoustic monitoring would be performed using a 
standardized method that would facilitate comparisons with other 
studies. Real-time monitoring of noise levels during in-water pile-
related activities would ensure sound levels do not surpass those 
estimated in SDOT's application. In the event noise does surpass 
estimated levels for extended periods of time, construction would be 
stopped and NMFS would be contacted to discuss the cause and potential 
solutions.

Reporting

    All marine mammal sightings would be documented by observers on a 
NMFS-approved sighting form. Takes of marine mammals would be recorded 
for any individual present within the area of potential effects. Marine 
mammal reporting would include all data described previously under 
Proposed Monitoring, including observation dates, times, and 
conditions, and any correlations of observed marine mammal behavior 
with activity type and received levels of sound, to the extent 
possible.
    SDOT would also submit a report(s) concerning the results of all 
acoustic monitoring. This report(s) would include:
     Size and type of piles;
     A detailed description of any sound attenuation device 
used, including design specifications;
     The impact hammer energy rating used to drive the piles, 
make and model of the hammer(s), and description of the vibratory 
hammer;
     A description of the sound monitoring equipment;
     The distance between hydrophones and depth of water and 
the hydrophone locations;
     The depth of the hydrophones;
     The distance from the pile to the water's edge;
     The depth of water in which the pile was driven
     The depth into the substrate that the pile was driven
     The physical characteristics of the bottom substrate into 
which the pile were driven;
     The total number of strikes to drive each pile;
     The results of the hydroacoustic monitoring, including the 
frequency spectrum, ranges and means for the peak and RMS sound 
pressure levels,

[[Page 22117]]

and an estimation of the distance at which RMS values reach the 
relevant marine mammal thresholds and background sound levels. 
Vibratory driving results would include the maximum and overall average 
RMS calculated from 30-s RMS values during the drive of the pile;
     A description of any observable marine mammal behavior in 
the immediate area and, if possible, correlation to underwater sound 
levels occurring at that time.
    Annual Reports--An annual report on marine mammal monitoring and 
mitigation would be submitted to NMFS, Office of Protected Resources, 
and NMFS, Northwest Regional Office. The annual reports would summarize 
information presented in the weekly reports and include data collected 
for each distinct marine mammal species observed in the project area, 
including descriptions of marine mammal behavior, overall numbers of 
individuals observed, frequency of observation, and any behavioral 
changes and the context of the changes relative to activities would 
also be included in the annual reports. Additional information that 
would be recorded during activities and contained in the reports 
include: date and time of marine mammal detections, weather conditions, 
species identification, approximate distance from the source, and 
activity at the construction site when a marine mammal is sighted.
    Comprehensive Final Report--In addition to annual reports, NMFS 
proposes to require SDOT to submit a draft comprehensive final report 
to NMFS, Office of Protected Resources, and NMFS, Northwest Regional 
Office, 180 days prior to the expiration of the regulations. This 
comprehensive technical report would provide full documentation of 
methods, results, and interpretation of all monitoring during the first 
4.5 years of the regulations. A revised final comprehensive technical 
report, including all monitoring results during the entire period of 
the regulations, would be due 90 days after the end of the period of 
effectiveness of the regulations.

Adaptive Management

    The final regulations governing the take of marine mammals 
incidental to the specified activities at Elliott Bay would contain an 
adaptive management component. In accordance with 50 CFR 216.105(c), 
regulations for the proposed activity must be based on the best 
available information. As new information is developed, through 
monitoring, reporting, or research, the regulations may be modified, in 
whole or in part, after notice and opportunity for public review. The 
use of adaptive management would allow NMFS to consider new information 
from different sources to determine if mitigation or monitoring 
measures should be modified (including additions or deletions) if new 
data suggest that such modifications are appropriate. The following are 
some of the possible sources of applicable data:
     Results from SDOT's monitoring from the previous year;
     Results from general marine mammal and sound research; or
     Any information which reveals that marine mammals may have 
been taken in a manner, extent, or number not authorized by these 
regulations or subsequent LOAs.
    If, during the effective dates of the regulations, new information 
is presented from monitoring, reporting, or research, these regulations 
may be modified, in whole or in part, after notice and opportunity of 
public review, as allowed for in 50 CFR 216.105(c). In addition, LOAs 
would be withdrawn or suspended if, after notice and opportunity for 
public comment, the Assistant Administrator finds, among other things, 
that the regulations are not being substantially complied with or that 
the taking allowed is having more than a negligible impact on the 
species or stock, as allowed for in 50 CFR 216.106(e). That is, should 
substantial changes in marine mammal populations in the project area 
occur or monitoring and reporting show that Elliott Bay Seawall actions 
are having more than a negligible impact on marine mammals, then NMFS 
reserves the right to modify the regulations and/or withdraw or suspend 
LOAs after public review.

Estimated Take by Incidental Harassment

    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].'' Take by Level B harassment only is 
anticipated as a result of the installation and removal of piles via 
impact and vibratory methods. No take by injury, serious injury, or 
death is anticipated.
    Typically, incidental take is estimated by multiplying the area of 
the zone of influence by the local animal density. This provides an 
estimate of the number of animals that might occupy the zone of 
influence at any time; however, there are no density estimates for 
marine mammal populations in Puget Sound. Therefore, the proposed take 
was estimated using anecdotal reports, incidental observations, and 
data from previous incidental take authorizations around Puget Sound. 
Anecdotal reports indicate that at most one to five individuals of each 
pinniped species may be present in the nearshore of the Seattle 
waterfront on a single day. Pinnipeds in the area are likely traveling 
to and from nearby haul-outs; harbor seals haul out around Alki Point, 
about 2.4 miles from the seawall and near Bainbridge Island, about six 
miles from the seawall; California sea lions haul out on buoys off Alki 
Point, between West Point and Skiff Point, and off Restoration Point, 
all about six miles from the seawall; and Steller sea lions haul out in 
Puget Sound near Bainbridge Island, seven miles from the seawall. Each 
pinniped haul out site is estimated to have less than 100 individuals, 
and the closest haul-out is 2.4 miles from the seawall. All other haul-
outs are outside of the area of potential effects. SDOT provided an 
overestimate of up to 50 individuals in the area of potential effects 
each day of pile driving activities. SDOT then used the estimated 
number of vibratory pile installation/removal days to calculate the 
maximum number of takes that may occur each year. SDOT's estimated 
takes for harbor seals are presented in Table 10 of their LOA 
application.
    However, NMFS determined that the take requests for pinnipeds are 
unreasonably overestimated. Considering (1) the lack of pinniped haul 
outs within the area of potential effects; (2) the likelihood that some 
animals may avoid the area during construction; (3) marine mammal 
surveys and take estimates from other projects in Puget Sound; and (4) 
anecdotal reports, NMFS estimates that a maximum of 20 harbor seals, 20 
California sea lions, and 10 Steller sea lions may be present within 
the Level B harassment isopleth each day. Furthermore, NMFS used 35 
days as the estimated number of vibratory and impact pile installation/
removal days each year (as opposed to just vibratory) to calculate 
potential take. The total days of pile installation/removal were 
calculated based on the information in Tables 3 through 5 of this 
document. These estimates are still considered to overestimate the 
actual number of takes that would occur because takes are

[[Page 22118]]

unlikely to occur during all impact pile driving activities (due to the 
smaller harassment isopleths) and the use of sound attenuation devices 
and other mitigation measures, which are not taken into consideration 
of the estimation of take. Furthermore, many takes would likely occur 
to the same individuals on different days and do not represent a total 
number of individuals.
    SDOT does not have any documented occurrence of harbor porpoises or 
Dall's porpoise in the area of potential effects. However, these 
species are known to occur in adjacent areas of Puget Sound and may 
pass by Elliott Bay during the proposed activity. Average pod sizes are 
nine and 1-2 for harbor porpoise and Dall's porpoise, respectively. 
Therefore, SDOT and NMFS overestimate that a maximum of nine harbor 
porpoises and two Dall's porpoise could occur within the Level B 
harassment isopleth during each day of vibratory pile installation/
removal. It is unlikely that any porpoises would be exposed to Level B 
take from impact pile driving due to the smaller harassment isopleths 
and absence from the nearshore area.
    NMFS considers the take of large whales to be less likely due to 
the designated exclusion zone and shutdown procedures designed to 
reduce take by Level B harassment, as described in the Proposed 
Mitigation section of this document. However, because the Level B 
harassment zone extends into Puget Sound (where large whales are more 
likely to transit), NMFS is proposing to authorize take for a limited 
number of large whales. Based on the average group size of two animals 
and observed occurrence around the proposed project area, NMFS 
estimates that up to eight gray whales and four humpback whales per 
year (up to 40 gray whales and 20 humpback whales total over a 5-year 
period) may be exposed to sound that constitutes Level B harassment. 
For these reasons, NMFS is proposing to authorize take of eight marine 
mammals species: harbor seal, California sea lion, Steller sea lion, 
harbor porpoise, Dall's porpoise, killer whale, gray whale, and 
humpback whale. NMFS' estimated take of each species is summarized in 
Table 8.

                        Table 8--Estimated Marine Mammal Takes for Proposed Authorization
----------------------------------------------------------------------------------------------------------------
                                           Estimated
                                        maximum number   Average number of pile      Estimated     Percentage of
                Species                  of takes per     driving days per year      number of    stock that may
                                              day                                 takes per year     be taken
----------------------------------------------------------------------------------------------------------------
Harbor seal...........................              20  35 (vibratory + impact).             700             4.8
California sea lion...................               5  35 (vibratory + impact).             175            <0.1
Steller sea lion......................               5  35 (vibratory + impact).             175             0.3
Harbor porpoise.......................               9  29 (vibratory)..........             315             2.9
Dall's porpoise.......................               2  29 (vibratory)..........              70             0.2
Killer whale (Southern resident)......  ..............  ........................              16              20
Killer whale (transient)..............  ..............  ........................              24             6.9
Gray whale............................  ..............  ........................               8            <0.1
Humpback whale........................  ..............  ........................               4             0.2
----------------------------------------------------------------------------------------------------------------

Negligible Impact and Small Numbers Analyses and Preliminary 
Determination

    NMFS has defined `negligible impact' in 50 CFR 216.103 as ``* * * 
an impact resulting from the specified activity that cannot be 
reasonably expected to, and is not reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.'' In making a negligible impact determination, 
NMFS considers a variety of factors, including but not limited to: (1) 
The number of anticipated mortalities; (2) the number and nature of 
anticipated injuries; (3) the number, nature, intensity, and duration 
of Level B harassment; and (4) the context in which the takes occur.
    Incidental take, in the form of Level B harassment only, is likely 
to occur as a result of marine mammal exposure to elevated levels of 
sound caused by impact and vibratory pile installation. No take by 
injury, serious injury, or death is anticipated or proposed to be 
authorized. By incorporating the proposed mitigation measures, 
including marine mammal monitoring and shut-down procedures described 
previously, harassment to individual marine mammals from the proposed 
activities is expected to be limited to temporary behavioral impacts. 
SDOT assumes that all individuals travelling past the project area 
would be exposed each time they pass the area and that all exposures 
would cause disturbance. NMFS agrees that this represents a worst-case 
scenario and is therefore sufficiently precautionary. There is only one 
pinniped haul-out located within the area of potential effects (2.4 
miles from the seawall). The shutdown zone monitoring proposed as 
mitigation, and the small size of the zones in which injury may occur, 
makes any potential injury of marine mammals extremely unlikely, and 
therefore discountable. Because marine mammal exposures would be 
limited to the period they are transiting the disturbance zone, with 
potential repeat exposures separated by days to weeks, the probability 
of experiencing TTS is also considered unlikely.
    These activities may cause individuals to temporarily disperse from 
the area or avoid transit through the area. However, existing traffic 
sound, commercial vessels, and recreational boaters already occur in 
the area. Thus, it is likely that marine mammals are habituated to 
these disturbances while transiting around and within Elliott Bay and 
would not be significantly hindered from transit. Behavioral changes 
are expected to potentially occur only when an animal is transiting a 
disturbance zone at the same time that the proposed activities are 
occurring. Although marine mammals are unlikely to be deterred from 
passing through the area, even temporarily, they may respond to the 
underwater sound by passing through the area more quickly, or they may 
experience stress as they pass through the area. Another possible 
effect is that the underwater sound would evoke a stress response in 
the exposed individuals, regardless of transit speed. However, the 
period of time during which an individual would be exposed to sound 
levels that might cause stress is short given their likely speed of 
travel through the affected areas. Considering the industrialized area 
where pile driving would occur, it is unlikely that the potential 
increased stress would have a significant effect on individuals or any 
effect on the population as a whole.
    Therefore, NMFS finds it unlikely that the amount of anticipated 
disturbance would significantly change marine

[[Page 22119]]

mammals' use of Elliott Bay. NMFS does not anticipate any effects on 
haul-out behavior because the closest haul-out is 2.4 miles from the 
seawall. All other effects of the proposed action are at most expected 
to have a discountable or insignificant effect on marine mammals, 
including an insignificant reduction in the quantity and quality of 
prey otherwise available.
    Any adverse effects to prey species would occur on a temporary 
basis during project construction. Given the restricted in-water work 
window designed for the protection of salmonids and the short-term 
nature of effects to fish populations, as well as conservation and 
habitat mitigation measures that would continue into the future, the 
project is not expected to have significant effects on the distribution 
or abundance of potential prey species in the long-term. Therefore, 
these temporary impacts are expected to have an inconsequential on 
habitat for pinniped prey species.
    A detailed description of potential impacts to individual pinnipeds 
was provided previously in this document. The following sections put 
into context what those effects mean to the respective populations or 
stocks of each of the marine mammal species potentially affected.

Harbor Seal

    There is no current abundance estimate of the Washington inland 
stock of harbor seals, but the last estimate (more than 8 years ago) 
was 14,612. While new data are needed, the population is thought to be 
stable. The estimated take (by behavioral harassment only) of 700 
individuals per year by Level B harassment is small relative to a 
stable population of approximately 14,612 (4.8 percent), and is not 
expected to impact annual rates of recruitment or survival of the 
stock. Harbor seals are not listed under the ESA nor considered 
depleted under the MMPA.

California Sea Lion

    The U.S. stock of California sea lions is estimated at 296,750 and 
may be at carrying capacity. Generally, California sea lions in the 
Pacific Northwest are subadult or adult males (NOAA, 2008). The 
estimated take (by behavioral harassment only) of 175 individuals per 
year is small relative to a population of approximately 296,750 (<0.1 
percent), and is not expected to impact annual rates of recruitment or 
survival of the stock. California sea lions are not listed under the 
ESA nor considered depleted under the MMPA.

Steller Sea Lion

    The total population of the eastern DPS of Steller sea lions is 
estimated to be within a range from approximately 58,334 to 72,223 
animals with an overall annual rate of increase of 3.1 percent 
throughout most of the range (Oregon to southeastern Alaska) since the 
1970s (Allen and Angliss, 2010). In 2006, the NMFS Steller sea lion 
recovery team proposed removal of the eastern stock from listing under 
the ESA based on its annual rate of increase. The total estimated take 
(by behavioral harassment only) of 175 individuals per year is small 
compared to a population of approximately 65,000 (0.3 percent).

Harbor Porpoise

    The total population of the Inland Washington stock was estimated 
to be 10,682 from 2002/2003 surveys. The estimated take (by behavioral 
harassment only) of an average of 315 individuals per year is small 
relative to a population of 10,682 (2.9 percent), and is not expected 
to impact annual rates of recruitment or survival of the stock. Harbor 
porpoises are not listed under the ESA nor considered depleted under 
the MMPA.

Dall's Porpoise

    The total population of the California/Oregon/Washington stock is 
estimated at about 42,000 individuals, based on coastal surveys from 
2005/2008. The PBR for this stock is 257 animals. The estimated take 
(by behavioral harassment only) of an average of 70 individuals per 
year is small relative to a population of 42,000 (0.2 percent), and is 
not expected to impact annual rates of recruitment or survival of the 
stock. Dall's porpoises are not listed under the ESA nor considered 
depleted under the MMPA.

Killer Whale

    The total population of the Eastern North Pacific Southern Resident 
stock is estimated at 86 individuals. The PBR for this stock is 0.17 
animals per year. The estimated take (by behavioral harassment only) of 
16 animals per year is small relative to the a population of 86 (19 
percent), and is not expected to impact annual rates of recruitment or 
survival of the stock. This is the maximum number of animals that would 
be exposed to elevated levels of sound per year and the proposed 
mitigation measures (e.g., marine mammal exclusion zone) would limit 
the number of exposures. The Eastern North Pacific Southern Resident 
stock of killer whales is listed as endangered under the ESA and 
considered depleted under the MMPA.
    The total population of the Eastern North Pacific transient stock 
is estimated to be a minimum of 346 individuals. The PBR for this stock 
is 2.8 animals per year. The estimated take (by behavioral harassment 
only) of an average of 24 animals per year is small relative to a 
population of 346 (6.9 percent), and is not expected to impact annual 
rates of recruitment or survival of the stock. This stock of transient 
killer whales is not listed under the ESA nor considered depleted under 
the MMPA.

Gray Whale

    The total population of the Eastern North Pacific stock is 
estimated at about 18,000 individuals. The PBR for this stock is 360 
animals. The estimated take (by behavioral harassment only) of an 
average of eight animals per year is small relative to a population of 
18,000 (<0.1 percent), and is not expected to impact annual rates of 
recruitment or survival of the stock. Gray whales are not listed under 
the ESA nor considered depleted under the MMPA.

Humpback Whale

    The total population of the California/Oregon/Washington stock is 
estimated at about 2,043 individuals. The PBR for this stock is 11.3 
animals per year. The estimated take (by behavioral harassment only) of 
an average of four animals per year is small relative to a population 
of 2,043 (0.2 percent), and is not expected to impact annual rates of 
recruitment or survival of the stock. Humpback whales are listed as 
endangered under the ESA and 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 proposed mitigation and 
monitoring measures, NMFS preliminarily finds that SDOT's proposed 
activities would result in the incidental take of small numbers of 
marine mammals, by Level B harassment only, and that the total taking 
from SDOT's proposed activities would have a negligible impact on the 
affected species or stocks.

Impact on Availability of Affected Species or Stock for Taking for 
Subsistence Uses

    Historically, Pacific Northwest treaty Indian tribes were known to 
utilize several species of marine mammals including, but not limited 
to: harbor seals, Steller sea lions, northern fur seals, gray whales, 
and humpback whales. More recently, several Pacific Northwest treaty 
Indian tribes have

[[Page 22120]]

promulgated tribal regulations allowing tribal members to exercise 
treaty rights for subsistence harvest of harbor seals and California 
sea lions (Caretta et al. 2007). The Makah Indian Tribe (Makah) has 
specifically passed hunting regulations for gray whales, however, the 
directed take of marine mammals (not just gray whales) for ceremonial 
and/or subsistence purposes was enjoined by the Ninth Circuit Court of 
Appeals in a ruling against the Makah in 2002, 2003, and 2004 (NMFS, 
2007). The issues surrounding the Makah gray whale hunt (in addition to 
the hunt for marine mammals in general) is currently in litigation or 
not yet clarified in recent court decisions. These issues also require 
National Environmental Policy Act (NEPA) and MMPA compliance, which has 
not yet been completed. Presently, there are no known active ceremonial 
and/or subsistence hunts for marine mammals in Puget Sound or the San 
Juan Islands with the following exceptions: (1) Tribes along the 
Pacific coast are most likely to still have regulations in place 
allowing a small number of directed take for subsistence purposes. It 
is unlikely that those regulations have been exercised in recent years, 
but they are likely still on the books. The Pacific Coast is separated 
by land and water bodies from the study area; and (2) Many tribes in 
Puget Sound and along the Pacific Coast have an additional current 
regulation that allows their fishermen to protect their life, gear, and 
catch from seals and California sea lions by lethal means. These rare 
takes are reported annually to NMFS by each tribe.
    There have been only a few reported takes of harbor seals from 
directed tribal subsistence hunts (Caretta et al. 2007). It is possible 
that a few seals have been taken in directed hunts because tribal 
fishers use seals caught incidental to fishing operations in the 
northern Washington marine set gillnet and Washington Puget Sound 
Region treaty salmon gillnet fisheries for their subsistence needs 
before undertaking a ceremonial or subsistence hunt (Caretta et al. 
2007). From communications with the tribes, the NMFS Northwest Regional 
Office believes that zero to five harbor seals from this stock (the 
Washington Inland Waters stock) may be taken annually in Puget Sound-
directed subsistence harvests (Caretta et al. 2007). The location of 
the hunted animals or hunting areas is not currently known.
    NMFS has determined that the total taking of affected species or 
stocks from the proposed Elliott Bay Seawall project would not have an 
unmitigable adverse impact on the availability of such species or 
stocks for taking for subsistence purposes.

Endangered Species Act (ESA)

    Steller sea lions are listed as threatened under the ESA. However, 
the eastern DPS was proposed for removal from listing under the ESA on 
April 18, 2012 (77 FR 23209), based on observed annual rates of 
increase. The public comment period was open through June 18, 2012, and 
NMFS has not yet made a final decision. The Eastern North Pacific 
Southern resident stock of killer whales and humpback whales are listed 
as endangered under the ESA. SDOT has initiated section 7 consultation 
with NMFS Northwest Regional Office, and NMFS Office of Protected 
Resources, Permits and Conservation Division will also consult 
internally on the proposed project. This consultation will be concluded 
prior to the promulgation of final regulations (if issued).

National Environmental Policy Act (NEPA)

    The Army Corps of Engineers is preparing an Environmental 
Assessment (EA) for the regulatory permit (section 404/10) required for 
Elliott Bay Seawall project. NMFS may adopt the Army Corps of 
Engineers' EA if it meets our needs. Otherwise NMFS will write our own 
EA to analyze the potential environmental effects of our proposed 
action of issuing an incidental take authorization. This will be 
concluded prior to our determination on the promulgation of final 
regulations.

Information Solicited

    NMFS requests interested persons to submit comments, information, 
and suggestions concerning the request and the content of the proposed 
regulations to govern the taking described herein (see ADDRESSES).

Classification

    The Office of Management and Budget (OMB) has determined that this 
proposed rule is not significant for purposes of Executive Order 12866.
    Pursuant to section 605(b) of the Regulatory Flexibility Act (RFA), 
the Chief Counsel for Regulation of the Department of Commerce has 
certified to the Chief Counsel for Advocacy of the Small Business 
Administration (SBA) that this proposed rule, if adopted, would not 
have a significant economic impact on a substantial number of small 
entities. The SBA defines small entity as a small business, small 
organization, or a small governmental jurisdiction. Applying this 
definition, there are no small entities that are impacted by this 
proposed rule. This proposed rule impacts only the activities of SDOT 
and the City of Seattle, who have submitted a request for authorization 
to take marine mammals incidental to construction within Elliott Bay, 
over the course of 5 years. SDOT and the City of Seattle are not 
considered to be small governmental jurisdictions under the RFA's 
definition. Under the RFA, governmental jurisdictions are considered to 
be small if they are ``governments of cities, counties, towns, 
townships, villages, school districts, or special districts, with a 
population of less than 50,000, unless an agency establishes, after 
opportunity for public comment, one or more definitions of such term 
which are appropriate to the activities of the agency and which are 
based on such factors as location in rural or sparsely populated areas 
or limited revenues due to the population of such jurisdiction, and 
publishes such definition(s) in the Federal Register.'' Because this 
proposed rule impacts only the activities of SDOT, which is not 
considered to be a small entity within SBA's definition, the Chief 
Counsel for Regulation certified that this proposed rule will not have 
a significant economic impact on a substantial number of small 
entities. As a result of this certification, a regulatory flexibility 
analysis is not required and none has been prepared.
    Notwithstanding any other provision of law, no person is required 
to respond to nor shall a person be subject to a penalty for failure to 
comply with a collection of information subject to the requirements of 
the Paperwork Reduction Act (PRA) unless that collection of information 
displays a currently valid OMB control number. This proposed rule 
contains collection-of-information requirements subject to the 
provisions of the PRA. These requirements have been approved by OMB 
under control number 0648-0151 and include applications for 
regulations, subsequent LOAs, and reports. Send comments regarding any 
aspect of this data collection, including suggestions for reducing the 
burden, to NMFS and the OMB Desk Officer (see ADDRESSES).

List of Subjects in 50 CFR Part 217

    Imports, Marine mammals, Reporting and recordkeeping requirements.


[[Page 22121]]


    Dated: April 4, 2013.
Alan D. Risenhoover,
Director, Office of Sustainable Fisheries, performing the functions and 
duties of the Deputy Assistant Administrator for Regulatory Programs, 
National Marine Fisheries Service.

    For reasons set forth in the preamble, 50 CFR part 217 is proposed 
to be amended as follows:

PART 217--REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS 
INCIDENTAL TO SPECIFIED ACTIVITIES

0
1. The authority citation for part 217 continues to read as follows:

    Authority:  16 U.S.C. 1361 et seq.

0
2. Subpart W is added to part 217 to read as follows:

Subpart W--Taking and Importing Marine Mammals; Elliott Bay Seawall 
Project
Sec.
217.220 Specified activity and specified geographical region.
217.221 [Reserved].
217.222 Permissible methods of taking.
217.223 Prohibitions.
217.224 Mitigation.
217.225 Requirements for monitoring and reporting.
217.226 Letters of Authorization.
217.227 Renewals and Modifications of Letters of Authorization.

Subpart W--Taking of Marine Mammals Incidental to the Elliott Bay 
Seawall Project


Sec.  217.220  Specified activity and specified geographical region.

    (a) Regulations in this subpart apply only to the Elliott Bay 
Seawall project and those persons it authorizes to conduct activities 
on its behalf for the taking of marine mammals that occurs in the area 
outlined in paragraph (b) of this section and that occurs incidental to 
seawall construction associated with the Elliott Bay Seawall project.
    (b) The taking of marine mammals by the Seattle Department of 
Transportation (SDOT) and the City of Seattle (City) may be authorized 
in a Letter of Authorization (LOA) only if it occurs in Elliott Bay, 
Washington.


Sec.  217.221  [Reserved]


Sec.  217.222  Permissible methods of taking.

    (a) Under LOAs issued pursuant to Sec. Sec.  216.106 and 217.226 of 
this chapter, the Holder of the LOA (hereinafter ``SDOT'' and ``City'') 
may incidentally, but not intentionally, take marine mammals within the 
area described in Sec.  217.220(b), provided the activity is in 
compliance with all terms, conditions, and requirements of the 
regulations in this subpart and the appropriate LOA.
    (b) The incidental take of marine mammals under the activities 
identified in Sec.  217.220(a) is limited to the indicated number of 
Level B harassment takes of the following species/stocks:
    (1) Harbor seal (Phoca vitulina)--3,200 (an average of 640 animals 
per year)
    (2) California sea lion (Zalophus californianus)--3,200 (an average 
of 640 animals per year)
    (3) Steller sea lion (Eumetopias jubatus)--800 (an average of 160 
animals per year)
    (4) Harbor porpoise (Phocoena phocoena)--871 (an average of 175 
animals per year)
    (5) Dall's porpoise (Phocoenoides dalli)--195 (an average of 39 
animals per year)
    (6) Killer whale (Orcinus orca), Eastern North Pacific Southern 
resident--80 (a maximum of 16 animals per year)
    (7) Killer whale (Orcinus orca), Eastern North Pacific transient--
120 (an average of of 24 animals per year)
    (8) Gray whale (Eschrichtius robustus)--40 (an average of 8 animals 
per year)
    (9) Humpback whale (Megaptera novaeangliae)--20 (an average of 4 
animals per year)


Sec.  217.223  Prohibitions.

    Notwithstanding takings contemplated in Sec.  217.222(b) and 
authorized by an LOA issued under Sec.  216.106 and Sec.  217.226 of 
this chapter, no person in connection with the activities described in 
Sec.  217.220 may:
    (a) Take any marine mammal not specified in Sec.  217.222(b);
    (b) Take any marine mammal specified in Sec.  217.222(b) other than 
by incidental, unintentional Level B harassment;
    (c) Take a marine mammal specified in Sec.  217.222(b) if NMFS 
determines such taking results in more than a negligible impact on the 
species or stock of such marine mammal; or
    (d) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or an LOA issued under Sec.  216.106 and 
Sec.  217.226 of this chapter.


Sec.  217.224  Mitigation.

    (a) When conducting the activities identified in Sec.  217.220(a), 
the mitigation measures contained in the LOA issued under Sec.  216.106 
and Sec.  217.226 of this chapter must be implemented. These mitigation 
measures include:
    (1) Limited impact pile driving. (i) All sheet piles shall be 
installed using a vibratory driver, unless impact driving is required 
to install piles that encounter consolidated sediments or for proofing 
load bearing sections.
    (ii) Any impact driver used in conjunction with vibratory pile 
driving shall employ sound attenuation devices, where applicable.
    (iii) Any attenuation devices that become available for vibratory 
pile driving shall be considered for additional mitigation.
    (2) Containment of impact pile driving. (i) The majority of 
permanent concrete piles shall be driven behind the temporary 
containment wall.
    (ii) [Reserved]
    (3) Additional attenuation measures. (i) Other attenuation devices 
shall be used as necessary to reduce sound levels.
    (ii) In the event that underwater sound monitoring shows that noise 
generation from pile installation exceeds the levels originally 
expected, SDOT and the City shall notify NMFS immediately to reevaluate 
the implementation of additional attenuation devices or other 
mitigation measures.
    (4) Ramp-up. (i) Ramp-up shall be used at the beginning of each 
day's in-water pile-related activities or if pile driving has ceased 
for more than 1 hour.
    (ii) If a vibratory hammer is used, contractors shall initiate 
sound from vibratory hammers for 15 seconds at reduced energy followed 
by a 1-minute waiting period. This procedure shall be repeated two 
additional times before full energy may be achieved.
    (iii) If a non-diesel impact hammer is used, contractors shall 
provide an initial set of strikes from the impact hammer at reduced 
energy, followed by a 1-minute waiting period, then two subsequent 
sets.
    (5) Marine mammal exclusion zones. (i) Exclusion zones shall be 
established to prevent the Level A harassment of all marine mammals and 
to reduce the Level B harassment of large whales.
    (A) An exclusion zone for pinnipeds and small cetaceans shall be 
established with a radius of 200 feet (61 meters) waterward of each 
steel sheet pile during impact pile driving;
    (B) An exclusion zone for pinnipeds and small cetaceans shall be 
established with a radius of 50 feet (15 meters) waterward of each 
concrete pile during impact pile driving;
    (C) An exclusion zone for large whales shall be established with a 
radius of 3,280 feet (1,000 meters) waterward of each steel sheet or 
concrete pile during impact pile driving;
    (D) An exclusion zone for large whales shall be established with a 
radius of 2.5 miles (3,981 meters)

[[Page 22122]]

waterward of each steel sheet pile during vibratory pile driving.
    (ii) Temporary buoys shall be used, as feasible, to mark the 
distance to each exclusion zone during in-water pile-related 
activities.
    (iii) The exclusion zones shall be used to provide a physical 
threshold for the shutdown of in-water pile-related activities.
    (iv) At the start of in-water pile related activities each day, a 
minimum of one qualified protected species observer shall be staged on 
land (or an adjacent pier) near the location of in-water pile-related 
activities to document and report any marine mammal that approaches or 
enters an exclusion zone throughout the day.
    (v) Additional land-based observers shall be deployed if needed to 
ensure the construction area is adequately monitored.
    (vi) Observers shall monitor for the presence of marine mammals 30 
minutes before, during, and for 30 minutes after any in-water pile-
related activities.
    (vii) Exclusion zones shall not be obscured by fog or poor lighting 
conditions during in-water pile-related activities.
    (6) Shutdown and delay procedures. (i) If a marine mammal is seen 
approaching or entering an exclusion zone (as specified in Sec.  
217.224(5)(i)), observers would immediately notify the construction 
personnel operating the pile-related equipment to shutdown pile-related 
activities.
    (ii) If a marine mammal(s) is present within the applicable 
exclusion zone prior to in-water pile-related activities, pile driving/
removal shall be delayed until the animal(s) has left the exclusion 
zone or until 15 minutes have elapsed without observing the animal.
    (7) Additional mitigation measures. Additional mitigation measures 
as contained in an LOA issued under Sec.  216.106 and Sec.  217.226 of 
this chapter.


Sec.  217.225  Requirements for monitoring and reporting.

    (a) When conducting the activities identified in Sec.  217.220(a), 
the monitoring and reporting measures contained in the LOA issued under 
Sec.  216.106 and Sec.  217.226 of this chapter must be implemented. 
These measures include:
    (1) Visual monitoring. (i) In addition to the mitigation monitoring 
described in Sec.  217.224 of this chapter, at least two protected 
species observers shall be positioned on land near the 2.5 mile 
exclusion zone to monitor for marine mammals during vibratory pile-
related activities or any other construction activities that may pose a 
threat to marine mammals.
    (A) Observers shall use the naked eye, wide-angle binoculars with 
reticles, and any other necessary equipment to scan the Level B 
harassment isopleth.
    (B) Observers shall work, on average, eight hours per day and shall 
be relieved by a fresh observer if pile driving lasts longer than usual 
(i.e., 12-16 hours).
    (C) The number of observers shall be increased and/or positions 
changed to ensure full visibility of the Level B harassment isopleth.
    (D) Land-based visual monitoring shall be conducted during all days 
of vibratory pile driving.
    (E) All land-based monitoring shall begin at least 30 minutes prior 
to the start of in-water pile-related activities and continue during 
active construction.
    (ii) At a minimum, observers shall record the following 
information:
    (A) Date of observation period, monitoring type (land-based/boat-
based), observer name and location, climate and weather conditions, and 
tidal conditions;
    (B) Environmental conditions that could confound marine mammal 
detections and when/where they occurred;
    (C) For each marine mammal sighting, the time of initial sighting 
and duration to the end of the sighting period;
    (D) Observed species, number, group composition, distance to pile-
related activities, and behavior of animals throughout the sighting;
    (E) Discrete behavioral reactions, if apparent;
    (F) Initial and final sighting locations marked on a grid map;
    (G) Pile-related activities taking place during each sighting and 
if/why a shutdown was or was not triggered; and
    (H) The number of takes (by species) of marine mammals, their 
locations, and behavior.
    (2) Acoustic monitoring. (i) Acoustic monitoring shall be conducted 
during in-water pile-related activities to identify or confirm noise 
levels for pile-related activities during in-water construction.
    (A) Acoustic data shall be collected using hydrophones connected to 
a drifting boat to reduce the effect of flow noise and an airborne 
microphone. There shall be a direct line of acoustic transmission 
through the water column between the pile and the hydrophones in all 
cases, without any interposing structures, including other piles.
    (B) A stationary two-channel hydrophone recording system shall be 
deployed to record a representative sample (subset of piles) during the 
monitoring period. Acoustic data shall be collected 1 m below the water 
surface and 1 m above the sea floor.
    (ii) Background noise recordings (in the absence of pile driving) 
shall be collected to provide a baseline background noise profile. The 
results and conclusions of the study shall be summarized and presented 
to NMFS with recommendations for any modifications to the monitoring 
plan or exclusion zones.
    (iii) All sensors, signal conditioning equipment, and sampling 
equipment shall be calibrated at the start of the monitoring period and 
rechecked at the start of each day.
    (iv) Prior to monitoring, water depth measurements shall be taken 
to ensure that hydrophones do not drag on the bottom during tidal 
changes.
    (v) Underwater and airborne acoustic monitoring shall occur for the 
first five steel sheet pile and the first five concrete piles during 
the duration of pile driving. If a representative sample has not been 
achieved after the five piles have been monitored (e.g., if there is 
high variability of sound levels between pilings), acoustic monitoring 
shall continue until a representative acoustic sample has been 
collected.
    (vi) Acoustic data shall be downloaded periodically (i.e., daily or 
on another appropriate schedule) and analyzed following the first year 
of construction. Post-analysis of underwater sound level signals shall 
include the following:
    (A) RMS values (average, standard deviation/error, minimum, and 
maximum) for each recorded pile. The 10-second RMS averaged values will 
be used for determining the source value and extent of the 120 dB 
underwater isopleth;
    (B) Frequency spectra for each functional hearing group; and
    (C) Standardized underwater source levels to a reference distance 
of 10 m (33 ft).
    (vii) Post-analysis of airborne noise would be presented in an 
unweighted format and include:
    (A) The unweighted RMS values (average, minimum, and maximum) for 
each recorded pile. The average values would be used for determining 
the extent of the airborne isopleths relative to species-specific 
criteria;
    (B) Frequency spectra from 10 Hz to 20 kHz for representative pile-
related activity; and
    (C) Standardized airborne source levels to a reference distance of 
approximately 15 m (50 ft).
    (viii) In the event noise levels surpass estimated levels for 
extended periods of

[[Page 22123]]

time, construction shall be stopped and NMFS shall be contacted to 
discuss the cause and potential solutions.
    (3) General reporting. (i) All marine mammal sightings shall be 
documented by observers on a NMFS-approved sighting form. Takes of 
marine mammals shall be recorded for any individual present within the 
area of potential effects.
    (ii) Marine mammal reporting shall include all data described 
previously under Proposed Monitoring, including observation dates, 
times, and conditions, and any correlations of observed marine mammal 
behavior with activity type and received levels of sound, to the extent 
possible.
    (iii) A report with the results of all acoustic monitoring shall 
include the following:
    (A) Size and type of piles;
    (B) A detailed description of any sound attenuation device used, 
including design specifications;
    (C) The impact hammer energy rating used to drive the piles, make 
and model of the hammer(s), and description of the vibratory hammer;
    (D) A description of the sound monitoring equipment;
    (E) The distance between hydrophones and depth of water and the 
hydrophone locations;
    (F) The depth of the hydrophones;
    (G) The distance from the pile to the water's edge;
    (H) The depth of water in which the pile was driven;
    (I) The depth into the substrate that the pile was driven;
    (J) The physical characteristics of the bottom substrate into which 
the pile were driven;
    (K) The total number of strikes to drive each pile;
    (L) The results of the hydroacoustic monitoring, including the 
frequency spectrum, ranges and means for the peak and RMS sound 
pressure levels, and an estimation of the distance at which RMS values 
reach the relevant marine mammal thresholds and background sound 
levels.
    (M) Vibratory driving results would include the maximum and overall 
average RMS calculated from 30-s RMS values during the drive of the 
pile; and
    (N) A description of any observable marine mammal behavior in the 
immediate area and, if possible, correlation to underwater sound levels 
occurring at that time.
    (iv) An annual report on monitoring and mitigation shall be 
submitted to NMFS, Office of Protected Resources, and NMFS, Northwest 
Regional Office.
    (A) The annual reports shall summarize include data collected for 
each marine mammal species observed in the project area, including 
descriptions of marine mammal behavior, overall numbers of individuals 
observed, frequency of observation, any behavioral changes and the 
context of the changes relative to activities would also be included in 
the annual reports, date and time of marine mammal detections, weather 
conditions, species identification, approximate distance from the 
source, and activity at the construction site when a marine mammal is 
sighted.
    (v) A draft comprehensive report on monitoring and mitigation shall 
be submitted to NMFS, Office of Protected Resources, and NMFS, 
Northwest Regional Office, 180 days prior to the expiration of the 
regulations.
    (A) The comprehensive technical report shall provide full 
documentation of methods, results, and interpretation of all monitoring 
during the first 4.5 years of the regulations. A revised final 
comprehensive technical report, including all monitoring results during 
the entire period of the regulations, shall be due 90 days after the 
end of the period of effectiveness of the regulations.
    (B) [Reserved]
    (4) Reporting injured or dead marine mammals. (i) In the 
unanticipated event that the specified activity clearly causes the take 
of a marine mammal in a manner prohibited by an LOA (if issued), such 
as an injury (Level A harassment), serious injury, or mortality, the 
Holder shall immediately cease the specified activities and report the 
incident to the Chief of the Permits and Conservation Division, Office 
of Protected Resources, NMFS, and the Northwest Regional Stranding 
Coordinator. The report must include the following information:
    (A) Time and date of the incident;
    (B) Description of the incident;
    (C) Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, and visibility);
    (D) Description of all marine mammal observations in the 24 hours 
preceding the incident;
    (E) Species identification or description of the animal(s) 
involved;
    (F) Fate of the animal(s); and
    (G) Photographs or video footage of the animal(s).
    (ii) Activities shall not resume until NMFS is able to review the 
circumstances of the prohibited take. NMFS will work with the Holder to 
determine what measures are necessary to minimize the likelihood of 
further prohibited take and ensure MMPA compliance. The Holder may not 
resume their activities until notified by NMFS.
    (iii) In the event that the Holder discovers an injured or dead 
marine mammal, and the lead protected species observer determines that 
the cause of the injury or death is unknown and the death is relatively 
recent (e.g., in less than a moderate state of decomposition), the 
Holder shall immediately report the incident to the Chief of the 
Permits and Conservation Division, Office of Protected Resources, NMFS, 
and the Northwest Regional Stranding Coordinator. The report must 
include the same information identified in Sec.  217.225(a)(3) of this 
chapter. Activities may continue while NMFS reviews the circumstances 
of the incident. NMFS will work with the Holder to determine whether 
additional mitigation measures or modifications to the activities are 
appropriate.
    (iv) In the event that the Holder discovers an injured or dead 
marine mammals, and the lead protected species observer determines that 
the injury or death is not associated with or related to the activities 
authorized in the LOA (e.g., previously wounded animal, carcass with 
moderate to advanced decomposition, or scavenger damage), the Holder 
shall report the incident to the Chief of the Permits and Conservation 
Division, Office of Protected Resources, NMFS, and the Northwest 
Regional Stranding Coordinator, within 24 hours of the discovery. The 
Holder shall provide photographs or video footage or other 
documentation of the stranding animal sighting to NMFS.
    (b) [Reserved]


Sec.  217.226  Letters of Authorization.

    (a) To incidentally take marine mammals pursuant to these 
regulations, the applicant must apply for and obtain an LOA.
    (b) An LOA, unless suspended or revoked, may be effective for a 
period of time not to exceed the expiration date of these regulations.
    (c) If an LOA expires prior to the expiration date of these 
regulations, the Holder must apply for and obtain a renewal of the LOA.
    (d) In the event of projected changes to the activity or to 
mitigation and monitoring measures required by an LOA, the Holder must 
apply for and obtain a modification of the LOA as described in Sec.  
217.227.
    (e) The LOA shall set forth:
    (1) Permissible methods of incidental taking;
    (2) Means of effecting the least practicable adverse impact (i.e., 
mitigation) on the species, its habitat,

[[Page 22124]]

and on the availability of the species for subsistence uses; and
    (3) Requirements for monitoring and reporting.
    (f) Issuance of the LOA shall be based on a determination that the 
level of taking will be consistent with the findings made for the total 
taking allowable under these regulations.
    (g) Notice of issuance or denial of an LOA shall be published in 
the Federal Register within 30 days of a determination.


Sec.  217.227  Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec. Sec.  216.106 and 217.226 of this 
chapter for the activity identified in Sec.  217.220(a) of this chapter 
shall be renewed or modified upon request by the applicant, provided 
that:
    (1) The proposed specified activity and mitigation, monitoring, and 
reporting measures, as well as the anticipated impacts, are the same as 
those described and analyzed for these regulations (excluding changes 
made pursuant to the adaptive management provision in Sec.  
217.227(c)(1)), and
    (2) NMFS determines that the mitigation, monitoring, and reporting 
measures required by the previous LOA under these regulations were 
implemented.
    (b) For LOA modification or renewal requests by the applicant that 
include changes to the activity or the mitigation, monitoring, or 
reporting (excluding changes made pursuant to the adaptive management 
provision in Sec.  217.227(c)(1)) that do not change the findings made 
for the regulations or result in no more than a minor change in the 
total estimated number of takes (or distribution by species or years), 
NMFS may publish a notice of proposed LOA in the Federal Register, 
including the associated analysis illustrating the change, and solicit 
public comments before issuing the LOA.
    (c) An LOA issued under Sec. Sec.  216.106 and 217.226 of this 
chapter for the activity identified in Sec.  217.220(a) may be modified 
by NMFS under the following circumstances:
    (1) Adaptive management. NMFS may modify (including augment) the 
existing mitigation, monitoring, or reporting measures (after 
consulting with the Holder regarding the practicability of the 
modifications) if doing so creates a reasonable likelihood of more 
effectively accomplishing the goals of the mitigation and monitoring 
set forth in the preamble for these regulations.
    (i) Possible sources of data that could contribute to the decision 
to modify the mitigation, monitoring, or reporting measures in an LOA 
include the following:
    (A) Results from the Holder's monitoring from the previous year(s);
    (B) Results from other marine mammal and/or sound research or 
studies;
    (C) Any information that reveals marine mammals may have been taken 
in a manner, extent, or number not authorized by these regulations or 
subsequent LOAs.
    (ii) If, through adaptive management, the modifications to the 
mitigation, monitoring, or reporting measures are substantial, NMFS 
will publish a notice of proposed LOA in the Federal Register and 
solicit public comments.
    (2) Emergencies. If NMFS determines that an emergency exists that 
poses a significant risk to the well-being of the species or stocks of 
marine mammals specified in Sec.  217.222(b), an LOA may be modified 
without prior notice or opportunity for public comment. A notice would 
be published in the Federal Register within 30 days of the action.

[FR Doc. 2013-08390 Filed 4-11-13; 8:45 am]
BILLING CODE 3510-22-P