Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Wharf Maintenance Project, 22477-22501 [2015-09253]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 80, Number 77 (Wednesday, April 22, 2015)]
[Notices]
[Pages 22477-22501]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-09253]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XD857


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

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

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

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

DATES: Comments and information must be received no later than May 22, 
2015.

ADDRESSES: Comments on the application should be addressed to Jolie 
Harrison, Chief, Permits and Conservation Division, Office of Protected 
Resources, National Marine Fisheries Service. Physical comments should 
be sent to 1315 East-West Highway, Silver Spring, MD 20910 and 
electronic comments should be sent to ITP.Laws@noaa.gov.
    Instructions: 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 by NMFS. Comments received electronically, 
including all attachments, must not exceed a 25-megabyte file size. 
Attachments to electronic comments will be accepted in Microsoft Word 
or Excel or Adobe PDF file formats only. All comments received are a 
part of the public record and will generally be posted for public 
viewing on the Internet at www.nmfs.noaa.gov/pr/permits/incidental/construction.htm without change. All personal identifying

[[Page 22478]]

information (e.g., name, address), confidential business information, 
or otherwise sensitive information submitted voluntarily by the sender 
will be publicly accessible.

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

SUPPLEMENTARY INFORMATION:

Availability

    An electronic copy of the Navy's application and supporting 
documents, as well as a list of the references cited in this document, 
may be obtained by visiting the Internet at: www.nmfs.noaa.gov/pr/permits/incidental/construction.htm. In case of problems accessing 
these documents, please call the contact listed above (see FOR FURTHER 
INFORMATION CONTACT).

National Environmental Policy Act (NEPA)

    The Navy prepared an Environmental Assessment (EA) to consider the 
direct, indirect and cumulative effects to the human environment 
resulting from the wharf maintenance project. NMFS has reviewed the EA 
and believes it appropriate to adopt the EA in order to assess the 
impacts to the human environment of issuance of an IHA to the Navy and 
subsequently sign our own Finding of No Significant Impact (FONSI). 
Information in the Navy's application, the Navy's EA, and this notice 
collectively provide the environmental information related to proposed 
issuance of this IHA for public review and comment. All documents are 
available at the aforementioned Web site. We will review all comments 
submitted in response to this notice as we complete the NEPA process, 
including a final decision of whether to adopt the Navy's EA and sign a 
FONSI, prior to a final decision on the incidental take authorization 
request.

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 by U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) within a specified area, the incidental, but not intentional, 
taking of small numbers of marine mammals, providing that certain 
findings are made and the necessary prescriptions are established.
    The incidental taking of small numbers of marine mammals may be 
allowed only if NMFS (through authority delegated by the Secretary) 
finds that the total taking by the specified activity during the 
specified time period will (i) have a negligible impact on the species 
or stock(s) and (ii) not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant). Further, the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such taking 
must be set forth.
    The allowance of such incidental taking under section 101(a)(5)(A), 
by harassment, serious injury, death, or a combination thereof, 
requires that regulations be established. Subsequently, a Letter of 
Authorization may be issued pursuant to the prescriptions established 
in such regulations, providing that the level of taking will be 
consistent with the findings made for the total taking allowable under 
the specific regulations. Under section 101(a)(5)(D), NMFS may 
authorize such incidental taking by harassment only, for periods of not 
more than one year, pursuant to requirements and conditions contained 
within an IHA. The establishment of these prescriptions requires notice 
and opportunity for public comment.
    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, section 3(18) of 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 November 4, 2014, we received a request from the Navy for 
authorization to take marine mammals incidental to pile driving and 
removal associated with maintenance of an explosives handling wharf 
(EHW-1) in the Hood Canal at Naval Base Kitsap in Bangor, WA (NBKB). 
The Navy submitted revised versions of the request on February 27 and 
March 17, 2015. The latter of these was deemed adequate and complete. 
The Navy proposes to replace four structurally unsound piles, between 
July 16, 2015, and January 15, 2016.
    The use of both vibratory and impact pile driving is expected to 
produce underwater sound at levels that have the potential to result in 
behavioral harassment of marine mammals. Species with the expected 
potential to be present during all or a portion of the in-water work 
window include the Steller sea lion (Eumetopias jubatus monteriensis), 
California sea lion (Zalophus californianus), harbor seal (Phoca 
vitulina richardii), killer whale (transient only; Orcinus orca), and 
harbor porpoise (Phocoena phocoena vomerina). These species may occur 
year-round in the Hood Canal, with the exception of the Steller sea 
lion, which is present only from fall to late spring (approximately 
late September to early May), and the California sea lion, which is 
only present from late summer to late spring (approximately late August 
to early June).
    This would be the third such IHA for similar work on the same 
structure, if issued. The Navy previously received IHAs for a two-year 
maintenance project at EHW-1 conducted in 2011-12 and 2012-13 (76 FR 
30130 and 77 FR 43049). Additional IHAs were issued to the Navy in 
recent years for marine construction projects on the NBKB waterfront, 
including the construction of a second explosives handling wharf (EHW-
2) immediately adjacent to EHW-1. Three consecutive IHAs were issued 
for that project, in 2012-13 (77 FR 42279), 2013-14 (78 FR 43148), and 
2014-15 (79 FR 43429). Additional projects include the Test Pile 
Project (TPP), conducted in 2011-12 in the proposed footprint of the 
EHW-2 to collect geotechnical data and test methodology in advance of 
the project (76 FR 38361) and a minor project to install a new mooring 
for an existing research barge, conducted in 2013-14 (78 FR 43165). In-
water work associated with all projects was conducted only during the 
approved in-water work window (July 16-February 15). Monitoring reports 
for all of these projects are available on the Internet at 
www.nmfs.noaa.gov/pr/permits/incidental/construction.htm and provide 
environmental information related to proposed issuance of this IHA for 
public review and comment.

Description of the Specified Activity

Overview

    NBKB provides berthing and support services to Navy submarines and 
other fleet assets. The Navy proposes to complete necessary maintenance 
at the EHW-1 facility at NBKB as part of ongoing maintenance conducted 
as necessary to maintain the structural

[[Page 22479]]

integrity of the wharf and ensure its continued functionality to 
support necessary operational requirements. The EHW-1 facility, 
constructed in 1977, requires ongoing maintenance due to the 
deterioration of the wharf's existing piling sub-structure. The 
proposed action includes the replacement of four existing 24-in hollow 
prestressed octagonal concrete piles with four new 30-in concrete 
filled steel pipe piles. Existing piles will be removed using a 
pneumatic hammer and a crane. Vibratory pile driving will be the 
primary method used to install new piles, though an impact hammer may 
be used if substrate conditions prevent the advancement of piles to the 
required depth or to verify the load-bearing capacity. Sound 
attenuation measures (i.e., bubble curtain) would be used during all 
impact hammer operations.

Dates and Duration

    The Navy's specified activity would occur only during July 16 
through January 15, within the allowable season for in-water work at 
NBKB. This window is established by the Washington Department of Fish 
and Wildlife in coordination with NMFS and the U.S. Fish and Wildlife 
Service (USFWS) to protect juvenile salmon. A maximum of eight pile 
driving days would occur, but the eight days could occur on any day 
during the window. Vibratory driving, as compared with impact driving 
or pile removal via pneumatic chipping, is expected to occur on only 
four total days.
    Impact pile driving during the first half of the in-water work 
window (July 16 to September 23) may only occur between two hours after 
sunrise and two hours before sunset to protect breeding marbled 
murrelets (Brachyramphus marmoratus; an Endangered Species Act [ESA]-
listed bird under the jurisdiction of USFWS). Vibratory driving during 
the first half of the window, and all in-water work conducted between 
September 23 and January 15, may occur during daylight hours (sunrise 
to sunset). Other construction (not in-water) may occur between 7 a.m. 
and 10 p.m., year-round. Therefore, in-water work is restricted to 
daylight hours (at minimum) and there is at least a nine-hour break 
during the 24-hour cycle from all construction activity.

Specific Geographic Region

    NBKB is located on the Hood Canal approximately 32 km west of 
Seattle, Washington (see Figures 2-1 through 2-3 in the Navy's 
application). The Hood Canal is a long, narrow fjord-like basin of the 
western Puget Sound. Throughout its 108-km length, the width of the 
canal varies from 1.6-3.2 km and exhibits strong depth/elevation 
gradients and irregular seafloor topography in many areas. Although no 
official boundaries exist along the waterway, the northeastern section 
extending from the mouth of the canal at Admiralty Inlet to the 
southern tip of Toandos Peninsula is referred to as northern Hood 
Canal. NBKB is located within this region. Please see Section 2 of the 
Navy's application for detailed information about the specific 
geographic region, including physical and oceanographic 
characteristics.

Detailed Description of Activities

    Maintenance of necessary facilities for handling of explosive 
materials is part of the Navy's sea-based strategic deterrence mission, 
and the Navy has determined that EHW-1 structural integrity is 
compromised due to deterioration of the wharf's piling sub-structure. 
The EHW-1 consists of two 30-m access trestles and a main pier deck 
that measures approximately 215 m in length. The wharf is supported by 
both 16-in and 24-in hollow octagonal pre-cast concrete piles. 
Additionally, there are steel and timber fender piles on the outboard 
and inboard edges of the wharf (see Figures 1-1 through 1-4 in the 
Navy's application).
    The Navy proposes to replace four structurally unsound 24-in hollow 
prestressed octagonal concrete piles, as well as performing additional 
repair and replacement work above water that would not be expected to 
result in effects to marine mammals. The piles would be replaced with 
four 30-in concrete filled steel piles. Piles to be removed would first 
be scored by a diver using a small pneumatic hammer and then removed by 
crane. Pile installation will utilize vibratory pile drivers to the 
greatest extent possible, and the Navy anticipates that most piles will 
be able to be vibratory driven to within several feet of the required 
depth. Pile drivability is, to a large degree, a function of soil 
conditions and the type of pile hammer. The soil conditions encountered 
during geotechnical explorations at NBKB indicate existing conditions 
generally consist of fill or sediment of very dense glacially 
overridden soils, and recent experience at other construction locations 
along the NBKB waterfront indicates that most piles should be able to 
be driven with a vibratory hammer to proper embedment depth. However, 
difficulties during pile driving may be encountered as a result of 
obstructions, such as rocks or boulders, which may exist throughout the 
project area. If difficult driving conditions occur, usage of an impact 
hammer would occur. Impact driving may also be used to verify load-
bearing capacity, or proof, installed piles.

Description of Marine Mammals in the Area of the Specified Activity

    There are eight marine mammal species with recorded occurrence in 
the Hood Canal during the past fifteen years, including five cetaceans 
and three pinnipeds. The harbor seal resides year-round in Hood Canal, 
while the Steller sea lion and California sea lion inhabit Hood Canal 
during portions of the year. Harbor porpoises may transit through the 
project area and occur regularly in Hood Canal, while transient killer 
whales could be present in the project area but do not have regular 
occurrence in the Hood Canal. The Dall's porpoise (Phocoenoides dalli 
dalli), humpback whale (Megaptera novaeangliae), and gray whale 
(Eschrichtius robustus) have been observed in Hood Canal, but their 
presence is sufficiently rare that we do not believe there is a 
reasonable likelihood of their occurrence in the project area during 
the proposed period of validity for this IHA. The latter three species 
are not carried forward for further analysis beyond this section.
    We have reviewed the Navy's detailed species descriptions, 
including life history information, for accuracy and completeness and 
refer the reader to Sections 3 and 4 of the Navy's application instead 
of reprinting the information here. Please also refer to NMFS' Web site 
(www.nmfs.noaa.gov/pr/species/mammals/) for generalized species 
accounts and to the Navy's Marine Resource Assessment for the Pacific 
Northwest, which documents and describes the marine resources that 
occur in Navy operating areas of the Pacific Northwest, including Puget 
Sound (DoN, 2006). The document is publicly available at: 
www.navfac.navy.mil/products_and_services/ev/products_and_services/marine_resources/marine_resource_assessments.html (accessed March 25, 
2015).
    Table 1 lists the marine mammal species with expected potential for 
occurrence in the vicinity of NBKB during the project timeframe and 
summarizes key information regarding stock status and abundance. 
Taxonomically, we follow Committee on Taxonomy (2014). Please see NMFS' 
Stock Assessment Reports (SAR), available at www.nmfs.noaa.gov/pr/sars, 
for more detailed accounts of these stocks' status and abundance. The 
harbor seal, California sea lion and harbor porpoise are addressed in 
the

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Pacific SARs (e.g., Carretta et al., 2014, 2015), while the Steller sea 
lion and transient killer whale are treated in the Alaska SARs (e.g., 
Allen and Angliss, 2014, 2015).
    In the species accounts provided here, we offer a brief 
introduction to the species and relevant stock as well as available 
information regarding population trends and threats, and describe any 
information regarding local occurrence.

                                           Table 1--Marine Mammals Potentially Present in the Vicinity of NBKB
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                                                                                     Stock abundance (CV,                         Relative occurrence in
              Species                         Stock            ESA/ MMPA status;       Nmin, most recent     PBR \3\   Annual M/   Hood Canal; season of
                                                              strategic (Y/N) \1\    abundance survey) \2\               SI \4\         occurrence
--------------------------------------------------------------------------------------------------------------------------------------------------------
                            Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
                                                                   Family Delphinidae
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Killer whale.......................  West coast transient    -; N.................  243 (n/a; 2009).......        2.4          0  Rare; year-round (but
                                      \6\.                                                                                         last observed in
                                                                                                                                   2005).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Family Phocoenidae (porpoises)
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Harbor porpoise....................  Washington inland       -; N.................  10,682 (0.38; 7,841;          unk      >=2.2  Possible regular
                                      waters \7\.                                    2003).                                        presence; year-round.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
                                                      Family Otariidae (eared seals and sea lions)
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California sea lion................  U.S...................  -; N.................  296,750 (n/a; 153,337;      9,200        389  Seasonal/common; Fall
                                                                                     2011).                                        to late spring (Aug
                                                                                                                                   to Jun).
Steller sea lion...................  Eastern U.S.\5\.......  -; N.................  60,131-74,448 (n/a;     1,645 \9\       92.3  Seasonal/occasional;
                                                                                     36,551; 2008-13) \8\.                         Fall to late spring
                                                                                                                                   (Sep to May).
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                                                             Family Phocidae (earless seals)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor seal........................  Hood Canal \7\........  -; N.................  3,555 (0.15; unk;             unk        0.2  Common; Year-round
                                                                                     1999).                                        resident.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or
  designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR (see
  footnote 3) or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For killer whales, the
  abundance values represent direct counts of individually identifiable animals; therefore there is only a single abundance estimate with no associated
  CV. For certain stocks of pinnipeds, abundance estimates are based upon observations of animals (often pups) ashore multiplied by some correction
  factor derived from knowledge of the species (or similar species) life history to arrive at a best abundance estimate; therefore, there is no
  associated CV. In these cases, the minimum abundance may represent actual counts of all animals ashore.
\3\ Potential biological removal, defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a
  marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population size (OSP).
\4\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
  fisheries, subsistence hunting, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value. All
  values presented here are from the draft 2014 SARs (www.nmfs.noaa.gov/pr/sars/draft.htm).
\5\ Abundance estimates (and resulting PBR values) for these stocks are new values presented in the draft 2014 SARs. This information was made available
  for public comment and is currently under review and therefore may be revised prior to finalizing the 2014 SARs. However, we consider this information
  to be the best available for use in this document.
\6\ The abundance estimate for this stock includes only animals from the ``inner coast'' population occurring in inside waters of southeastern Alaska,
  British Columbia, and Washington--excluding animals from the ``outer coast'' subpopulation, including animals from California--and therefore should be
  considered a minimum count. For comparison, the previous abundance estimate for this stock, including counts of animals from California that are now
  considered outdated, was 354.
\7\ Abundance estimates for these stocks are greater than eight years old and are therefore not considered current. PBR is considered undetermined for
  these stocks, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates,
  as these represent the best available information for use in this document.
\8\ Best abundance is calculated as the product of pup counts and a factor based on the birth rate, sex and age structure, and growth rate of the
  population. A range is presented because the extrapolation factor varies depending on the vital rate parameter resulting in the growth rate (i.e.,
  high fecundity or low juvenile mortality).
\9\ PBR is calculated for the U.S. portion of the stock only (excluding animals in British Columbia) and assumes that the stock is not within its OSP.
  If we assume that the stock is within its OSP, PBR for the U.S. portion increases to 2,193.

    Although present in Washington inland waters in small numbers 
(Falcone et al., 2005), primarily in the Strait of Juan de Fuca and San 
Juan Islands but also occasionally in Puget Sound, the humpback whale 
is not typically present in Hood Canal. Archived sighting records show 
no confirmed observations from 2001-11 (www.orcanetwork.org; accessed 
March 26, 2015), and no records are found in the literature. In 
January-February of 2012, and again in 2015, one individual was 
observed in Hood Canal repeatedly over a period of several weeks. No 
other sightings have been recorded.
    Gray whales generally migrate southbound past Washington in late 
December and January, and transit past

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Washington on the northbound return in March to May. Gray whales do not 
generally make use of Washington inland waters, but have been observed 
in certain portions of those waters in all months of the year, with 
most records occurring from March through June (Calambokidis et al., 
2010; www.orcanetwork.org) and associated with regular feeding areas. 
Usually fewer than twenty gray whales visit the inner marine waters of 
Washington and British Columbia beginning in about January, and six to 
ten of these are individual whales that return most years to feeding 
sites in northern Puget Sound. The remaining individuals occurring in 
any given year generally appear unfamiliar with feeding areas, often 
arrive emaciated, and commonly die of starvation (WDFW, 2012). Gray 
whales have been sighted in Hood Canal on six occasions since 1999 
(including a stranded whale), with the most recent report in November 
2010 (www.orcanetwork.org).
    In Washington, Dall's porpoises are most abundant in offshore 
waters where they are year-round residents, although interannual 
distribution is highly variable (Green et al., 1992). In inland waters, 
Dall's porpoises are most frequently observed in the Strait of Juan de 
Fuca and Haro Strait between San Juan Island and Vancouver Island 
(Nysewander et al., 2005), but are seen occasionally in southern Puget 
Sound and may also occasionally occur in Hood Canal. Only a single 
Dall's porpoise has been observed at NBKB, in deeper water during a 
2008 summer survey conducted by the Navy (Tannenbaum et al., 2009). On 
the basis of this single observation, we previously assumed it 
appropriate to authorize incidental take of this species. However, 
there have been no subsequent observations of Dall's porpoises in Hood 
Canal during either dedicated vessel line-transect surveys or project-
specific monitoring and we no longer believe that the species may be 
reasonably expected to be present in the action area.

Steller Sea Lion

    Steller sea lions are distributed mainly around the coasts to the 
outer continental shelf along the North Pacific rim from northern 
Hokkaido, Japan through the Kuril Islands and Okhotsk Sea, Aleutian 
Islands and central Bering Sea, southern coast of Alaska and south to 
California (Loughlin et al., 1984). Based on distribution, population 
response, and phenotypic and genotypic data, two separate stocks of 
Steller sea lions are recognized within U.S. waters, with the 
population divided into western and eastern distinct population 
segments (DPS) at 144[deg]W (Cape Suckling, Alaska) (Loughlin, 1997). 
The eastern DPS extends from California to Alaska, including the Gulf 
of Alaska, and is the only stock that may occur in the Hood Canal.
    According to NMFS' recent status review (NMFS, 2013), the best 
available information indicates that the overall abundance of eastern 
DPS Steller sea lions has increased for a sustained period of at least 
three decades while pup production has also increased significantly, 
especially since the mid-1990s. Johnson and Gelatt (2012) provided an 
analysis of growth trends of the entire eastern DPS from 1979-2010, 
indicating that the stock increased during this period at an annual 
rate of 4.2 percent (90% CI 3.7-4.6). Most of the overall increase 
occurred in the northern portion of the range (southeast Alaska and 
British Columbia), but pup counts in Oregon and California also 
increased significantly (e.g., Merrick et al., 1992; Sease et al., 
2001; Olesiuk and Trites, 2003; Fritz et al. 2008; Olesiuk, 2008; NMFS, 
2008, 2013). In Washington, Pitcher et al. (2007) reported that Steller 
sea lions, presumably immature animals and non-breeding adults, 
regularly used four haul-outs, including two ``major'' haul-outs (>50 
animals). The same study reported that the numbers of sea lions counted 
between 1989 and 2002 on Washington haul-outs increased significantly 
(average annual rate of 9.2 percent) (Pitcher et al., 2007). Although 
the stock size has increased, its status relative to OSP size is 
unknown. However, the consistent long-term estimated annual rate of 
increase may indicate that the stock is reaching OSP size (Allen and 
Angliss, 2014).
    The eastern stock breeds in rookeries located in southeast Alaska, 
British Columbia, Oregon, and California. There are no known breeding 
rookeries in Washington (Allen and Angliss, 2014) but eastern stock 
Steller sea lions are present year-round along the outer coast of 
Washington, including immature animals or non-breeding adults of both 
sexes. In 2011, the minimum count for Steller sea lions in Washington 
was 1,749 (Allen and Angliss, 2014), up from 516 in 2001 (Pitcher et 
al., 2007). In Washington, Steller sea lions primarily occur at haul-
out sites along the outer coast from the Columbia River to Cape 
Flattery and in inland waters sites along the Vancouver Island 
coastline of the Strait of Juan de Fuca (Jeffries et al., 2000; Olesiuk 
and Trites, 2003; Olesiuk, 2008). Numbers vary seasonally in Washington 
waters with peak numbers present during the fall and winter months 
(Jeffries et al., 2000). Beginning in 2008, Steller sea lions have been 
observed at NBKB hauled out on submarines at Delta Pier (located 
approximately 1.25 km south of the project site) during fall through 
spring months, with September 26 as the earliest documented arrival. 
When Steller sea lions are present, there are typically one to four 
individuals, with a maximum observed group size of eleven.

Harbor Seal

    Harbor seals inhabit coastal and estuarine waters and shoreline 
areas of the northern hemisphere from temperate to polar regions. The 
eastern North Pacific subspecies is found from Baja California north to 
the Aleutian Islands and into the Bering Sea. Multiple lines of 
evidence support the existence of geographic structure among harbor 
seal populations from California to Alaska (e.g., O'Corry-Crowe et al., 
2003; Temte, 1986; Calambokidis et al., 1985; Kelly, 1981; Brown, 1988; 
Lamont, 1996; Burg, 1996). Harbor seals are generally non-migratory, 
and analysis of genetic information suggests that genetic differences 
increase with geographic distance (Westlake and O'Corry-Crowe, 2002). 
However, because stock boundaries are difficult to meaningfully draw 
from a biological perspective, three separate harbor seal stocks have 
been recognized for management purposes along the west coast of the 
continental U.S.: (1) Inland waters of Washington (including Hood 
Canal, Puget Sound, and the Strait of Juan de Fuca out to Cape 
Flattery), (2) outer coast of Oregon and Washington, and (3) California 
(Carretta et al., 2014). Multiple stocks are recognized in Alaska. 
Samples from Washington, Oregon, and California demonstrate a high 
level of genetic diversity and indicate that the harbor seals of 
Washington inland waters possess unique haplotypes not found in seals 
from the coasts of Washington, Oregon, and California (Lamont et al., 
1996).
    Recent genetic evidence indicates that harbor seals of Washington 
inland waters have sufficient population structure to warrant division 
into multiple distinct stocks (Huber et al., 2010, 2012). Based on 
studies of pupping phenology, mitochondrial DNA, and microsatellite 
variation, Carretta et al. (2014) divide the Washington inland waters 
stock into three new populations, and present these as stocks: (1) 
Southern Puget Sound (south of the Tacoma Narrows Bridge); (2) 
Washington northern inland waters (including Puget Sound north of the 
Tacoma Narrows Bridge, the San

[[Page 22482]]

Juan Islands, and the Strait of Juan de Fuca); and (3) Hood Canal. Only 
the Hood Canal stock of harbor seals is expected to occur in the action 
area.
    The best available abundance estimate was derived from aerial 
surveys of harbor seals in Washington conducted during the pupping 
season in 1999, during which time the total numbers of hauled-out seals 
(including pups) were counted (711; Jeffries et al., 2003). Radio-
tagging studies conducted at six locations collected information on 
harbor seal haul-out patterns in 1991-92, resulting in a pooled 
correction factor (across three coastal and three inland sites) of 1.53 
to account for animals in the water which are missed during the aerial 
surveys (Huber et al., 2001), which, coupled with the aerial survey 
counts, previously provided the abundance estimate. More recent tagging 
information specifically conducted in Hood Canal suggests that harbor 
seals in Hood Canal haul out twenty percent of the time (London et al., 
2012). Therefore, the aerial surveys represented only twenty percent of 
the population, and the abundance estimate has been revised accordingly 
(see Table 1).
    Harbor seal counts in Washington State increased at an annual rate 
of six percent from 1983-96, increasing to ten percent for the period 
1991-96 (Jeffries et al., 1997). The population is thought to be 
stable, and harbor seals in Washington inland waters have generally 
been considered to be within OSP size (Jeffries et al., 2003).
    Harbor seals are the most abundant marine mammal in Hood Canal, 
where they can occur anywhere year-round and are considered resident, 
and are the only pinniped that breeds in inland Washington waters 
(Jeffries et al., 2003). They are year-round, non-migratory residents, 
pup (i.e., give birth) in Hood Canal, and the population is considered 
closed, meaning that they do not have much movement outside of Hood 
Canal (London, 2006). Surveys in the Hood Canal from the mid-1970s to 
2000 show a fairly stable population between 600-1,200 seals, and the 
abundance of harbor seals in Hood Canal has likely stabilized at its 
carrying capacity of approximately 1,000 seals (Jeffries et al., 2003). 
Harbor seals have been consistently sighted during Navy surveys, found 
in all marine habitats including nearshore waters and deeper water, and 
have been observed hauled out on manmade objects such as buoys (Agness 
and Tannenbaum, 2009; Tannenbaum et al., 2009, 2011). Harbor seals were 
commonly observed in the water during monitoring conducted for other 
projects at NBKB in 2011-13 (HDR, 2012a, 2012b; Hart Crowser, 2013).
    The project area is not known as a regular pupping or haul-out 
site, as harbor seals in Hood Canal prefer river deltas and exposed 
tidal areas (London, 2006). The closest haul-out to the project area is 
approximately 16 km southwest of NBKB at Dosewallips River mouth, 
outside the potential area of effect for this project (see Figure 4-1 
of the Navy's application). However, recent observations have shown 
that harbor seals frequently haul-out opportunistically along the NBKB 
waterfront (though not on many of the larger structures, which are 
inaccessible to harbor seals, or on docked submarines, which are 
favored by sea lions) and that pupping does occur along the NBKB 
waterfront. Pupping has been observed on the NBKB waterfront at 
Carderock Pier and Service Pier (both locations over a mile south of 
the project site), and a harbor seal neonate was observed on a small 
floating dock near the project site in 2013. Evidence of pupping has 
been observed in other locations, and Navy biologists now believe that 
pupping may occur regularly at the Service Pier. During most of the 
year, all age and sex classes (except neonates) occur in the project 
area throughout the period of construction activity. Despite evidence 
of pupping, harbor seal neonates would not generally be expected to be 
present during pile driving.

California Sea Lion

    California sea lions range from the Gulf of California north to the 
Gulf of Alaska, with breeding areas located in the Gulf of California, 
western Baja California, and southern California. Five genetically 
distinct geographic populations have been identified: (1) Pacific 
temperate, (2) Pacific subtropical, and (3-5) southern, central, and 
northern Gulf of California (Schramm et al., 2009). Rookeries for the 
Pacific temperate population are found within U.S. waters and just 
south of the U.S.-Mexico border, and animals belonging to this 
population may be found from the Gulf of Alaska to Mexican waters off 
Baja California. For management purposes, a stock of California sea 
lions comprising those animals at rookeries within the U.S. is defined 
(i.e., the U.S. stock of California sea lions) (Carretta et al., 2014). 
Pup production at the Coronado Islands rookery in Mexican waters is 
considered an insignificant contribution to the overall size of the 
Pacific temperate population (Lowry and Maravilla-Chavez, 2005).
    Trends in pup counts from 1975 through 2008 have been assessed for 
four rookeries in southern California and for haul-outs in central and 
northern California. During this time period counts of pups increased 
at an annual rate of 5.4 percent, excluding six El Ni[ntilde]o years 
when pup production declined dramatically before quickly rebounding 
(Carretta et al., 2014). The maximum population growth rate was 9.2 
percent when pup counts from the El Ni[ntilde]o years were removed. 
There are indications that the California sea lion may have reached or 
is approaching carrying capacity, although more data are needed to 
confirm that leveling in growth persists (Carretta et al., 2014).
    Sea lion mortality has been linked to the algal-produced neurotoxin 
domoic acid (Scholin et al., 2000). Future mortality may be expected to 
occur, due to the sporadic occurrence of such harmful algal blooms. 
There is currently an Unusual Mortality Event (UME) declaration in 
effect for California sea lions. Beginning in January 2013, elevated 
strandings of California sea lion pups have been observed in southern 
California, with live sea lion strandings nearly three times higher 
than the historical average. Findings to date indicate that a likely 
contributor to the large number of stranded, malnourished pups was a 
change in the availability of sea lion prey for nursing mothers, 
especially sardines. The causes and mechanisms of this UME remain under 
investigation (www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm; accessed March 28, 2015).
    An estimated 3,000 to 5,000 California sea lions migrate northward 
along the coast to central and northern California, Oregon, Washington, 
and Vancouver Island during the non-breeding season from September to 
May (Jeffries et al., 2000) and return south the following spring 
(Mate, 1975; Bonnell et al., 1983). In past years, peak numbers of up 
to 1,000 California sea lions occur in Puget Sound (including Hood 
Canal) during this time period (Jeffries et al., 2000). Given the 
overall population increase, it is likely that seasonal occurrence in 
Puget Sound has also increased.
    California sea lions are present in Hood Canal during much of the 
year with the exception of mid-June through August, and occur regularly 
at NBKB, as observed during Navy waterfront surveys conducted from 
April 2008 through December 2013 (DoN, 2013). They are known to utilize 
a diversity of man-made structures for hauling out (Riedman, 1990) and, 
although there are no regular California sea lion haul-outs known 
within the Hood Canal (Jeffries

[[Page 22483]]

et al., 2000), they are frequently observed hauled out at several 
opportune areas at NBKB (e.g., submarines, floating security fence, 
barges). All documented instances of California sea lions hauling out 
at NBKB have been on submarines docked at Delta Pier, where a maximum 
of 122 California sea lions have been observed at any one time (DoN, 
2013), and on pontoons of the NBKB floating security fence.

Killer Whale

    Killer whales are one of the most cosmopolitan marine mammals, 
found in all oceans with no apparent restrictions on temperature or 
depth, although they do occur at higher densities in colder, more 
productive waters at high latitudes and are more common in nearshore 
waters (Leatherwood and Dahlheim, 1978; Forney and Wade, 2006). Killer 
whales are found throughout the North Pacific, including the entire 
Alaska coast, in British Columbia and Washington inland waterways, and 
along the outer coasts of Washington, Oregon, and California. On the 
basis of differences in morphology, ecology, genetics, and behavior, 
populations of killer whales have largely been classified as 
``resident'', ``transient'', or ``offshore'' (e.g., Dahlheim et al., 
2008). Several studies have also provided evidence that these ecotypes 
are genetically distinct, and that further genetic differentiation is 
present between subpopulations of the resident and transient ecotypes 
(e.g., Barrett-Lennard, 2000). The taxonomy of killer whales is 
unresolved, with expert opinion generally following one of two lines: 
Killer whales are either (1) a single highly variable species, with 
locally differentiated ecotypes representing recently evolved and 
relatively ephemeral forms not deserving species status, or (2) 
multiple species, supported by the congruence of several lines of 
evidence for the distinctness of sympatrically occurring forms (Krahn 
et al., 2004). Resident and transient whales are currently considered 
to be unnamed subspecies (Committee on Taxonomy, 2014).
    The resident and transient populations have been divided further 
into different subpopulations on the basis of genetic analyses, 
distribution, and other factors. Recognized stocks in the North Pacific 
include Alaska residents; northern residents; southern residents; Gulf 
of Alaska, Aleutian Islands, and Bering Sea transients; and west coast 
transients, along with a single offshore stock. See Allen and Angliss 
(2014) for more detail about these stocks. West coast transient killer 
whales, which occur from California through southeastern Alaska, are 
the only type expected to potentially occur in the project area.
    It is thought that the stock grew rapidly from the mid-1970s to 
mid-1990s as a result of a combination of high birth rate, survival, as 
well as greater immigration of animals into the nearshore study area 
(DFO, 2009). The rapid growth of the population during this period 
coincided with a dramatic increase in the abundance of the whales' 
primary prey, harbor seals, in nearshore waters. Population growth 
began slowing in the mid-1990s and has continued to slow in recent 
years (DFO, 2009). Population trends and status of this stock relative 
to its OSP level are currently unknown. Analyses in DFO (2009) 
estimated a rate of increase of about six percent per year from 1975 to 
2006, but this included recruitment of non-calf whales into the 
population.
    Transient occurrence in inland waters appears to peak during August 
and September, which is the peak time for harbor seal pupping, weaning, 
and post-weaning (Baird and Dill, 1995). The number of transient killer 
whales in Washington waters at any one time is probably fewer than 
twenty individuals (Wiles, 2004). In 2003 and 2005, small groups of 
transient killer whales (eleven and six individuals, respectively) were 
present in Hood Canal for significant periods of time (59 and 172 days, 
respectively) between the months of January and July. While present, 
the whales preyed on harbor seals in the subtidal zone of the nearshore 
marine and inland marine deeper water habitats (London, 2006).

Harbor Porpoise

    Harbor porpoises are found primarily in inshore and relatively 
shallow coastal waters (< 100 m) from Point Barrow (Alaska) to Point 
Conception (California). Various genetic analyses and investigation of 
pollutant loads indicate a low mixing rate for harbor porpoises along 
the west coast of North America and likely fine-scale geographic 
structure along an almost continuous distribution from California to 
Alaska (e.g., Calambokidis and Barlow, 1991; Osmek et al., 1994; 
Chivers et al., 2002, 2007). However, stock boundaries are difficult to 
draw because any rigid line is generally arbitrary from a biological 
perspective. On the basis of genetic data and density discontinuities 
identified from aerial surveys, eight stocks have been identified in 
the eastern North Pacific, including northern Oregon/Washington coastal 
and inland Washington stocks (Carretta et al., 2013a). The Washington 
inland waters stock includes individuals found east of Cape Flattery 
and is the only stock that may occur in the project area.
    Although long-term harbor porpoise sightings in southern Puget 
Sound declined from the 1940s through the 1990s, sightings and 
strandings have increased in Puget Sound and northern Hood Canal in 
recent years and harbor porpoise are now considered to regularly occur 
year-round in these waters (Carretta et al., 2014). Reasons for the 
apparent decline, as well as the apparent rebound, are unknown. Recent 
observations may represent a return to historical conditions, when 
harbor porpoises were considered one of the most common cetaceans in 
Puget Sound (Scheffer and Slipp, 1948). The status of harbor porpoises 
in Washington inland waters relative to OSP is not known (Carretta et 
al., 2014).
    In 2006, a UME was declared for harbor porpoises throughout Oregon 
and Washington, and a total of 114 strandings were reported in 2006-07. 
The cause of the UME has not been determined and several factors, 
including contaminants, genetics, and environmental conditions, are 
still being investigated (Carretta et al., 2014).
    Prior to recent construction projects conducted by the Navy at 
NBKB, harbor porpoises were considered to have only occasional 
occurrence in the project area. A single harbor porpoise had been 
sighted in deeper water at NBKB during 2010 field observations 
(Tannenbaum et al., 2011). However, while implementing monitoring plans 
for work conducted from July-October, 2011, the Navy recorded multiple 
sightings of harbor porpoise in the deeper waters of the project area 
(HDR, 2012). Following these sightings, the Navy conducted dedicated 
line transect surveys, recording multiple additional sightings of 
harbor porpoises, and have revised local density estimates accordingly.

Potential Effects of the Specified Activity on Marine Mammals

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals. This 
discussion also includes reactions that we consider to rise to the 
level of a take and those that we do not consider to rise to the level 
of a take (for example, with acoustics, we may include a discussion of 
studies that showed animals not reacting at all to sound or exhibiting 
barely measurable avoidance). This section is intended as a background 
of potential effects and does not consider either the

[[Page 22484]]

specific manner in which this activity will be carried out or the 
mitigation that will be implemented, and how either of those will shape 
the anticipated impacts from this specific activity. The ``Estimated 
Take by Incidental Harassment'' section later in this document will 
include a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The ``Negligible Impact 
Analysis'' section will include the analysis of how this specific 
activity will impact marine mammals and will consider the content of 
this section, the ``Estimated Take by Incidental Harassment'' section, 
the ``Proposed Mitigation'' section, and the ``Anticipated Effects on 
Marine Mammal Habitat'' section to draw conclusions regarding the 
likely impacts of this activity on the reproductive success or 
survivorship of individuals and from that on the affected marine mammal 
populations or stocks. In the following discussion, we provide general 
background information on sound and marine mammal hearing before 
considering potential effects to marine mammals from sound produced by 
vibratory and impact pile driving.

Description of Sound Sources

    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks of a sound wave; lower frequency sounds have 
longer wavelengths than higher frequency sounds and attenuate 
(decrease) more rapidly in shallower water. Amplitude is the height of 
the sound pressure wave or the `loudness' of a sound and is typically 
measured using the decibel (dB) scale. A dB is the ratio between a 
measured pressure (with sound) and a reference pressure (sound at a 
constant pressure, established by scientific standards). It is a 
logarithmic unit that accounts for large variations in amplitude; 
therefore, relatively small changes in dB ratings correspond to large 
changes in sound pressure. When referring to sound pressure levels 
(SPLs; the sound force per unit area), sound is referenced in the 
context of underwater sound pressure to 1 microPascal ([mu]Pa). One 
pascal is the pressure resulting from a force of one newton exerted 
over an area of one square meter. The source level (SL) represents the 
sound level at a distance of 1 m from the source (referenced to 1 
[mu]Pa). The received level is the sound level at the listener's 
position. Note that all underwater sound levels in this document are 
referenced to a pressure of 1 [mu]Pa and all airborne sound levels in 
this document are referenced to a pressure of 20 [mu]Pa.
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Rms is calculated by squaring all of the 
sound amplitudes, averaging the squares, and then taking the square 
root of the average (Urick, 1983). Rms accounts for both positive and 
negative values; squaring the pressures makes all values positive so 
that they may be accounted for in the summation of pressure levels 
(Hastings and Popper, 2005). This measurement is often used in the 
context of discussing behavioral effects, in part because behavioral 
effects, which often result from auditory cues, may be better expressed 
through averaged units than by peak pressures.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in all 
directions away from the source (similar to ripples on the surface of a 
pond), except in cases where the source is directional. The 
compressions and decompressions associated with sound waves are 
detected as changes in pressure by aquatic life and man-made sound 
receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al., 1995), and the sound level 
of a region is defined by the total acoustical energy being generated 
by known and unknown sources. These sources may include physical (e.g., 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
sound (e.g., vessels, dredging, aircraft, construction). A number of 
sources contribute to ambient sound, including the following 
(Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient noise for frequencies between 200 Hz and 50 
kHz (Mitson, 1995). In general, ambient sound levels tend to increase 
with increasing wind speed and wave height. Surf noise becomes 
important near shore, with measurements collected at a distance of 8.5 
km from shore showing an increase of 10 dB in the 100 to 700 Hz band 
during heavy surf conditions.
     Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total noise at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times.
     Biological: Marine mammals can contribute significantly to 
ambient noise levels, as can some fish and shrimp. The frequency band 
for biological contributions is from approximately 12 Hz to over 100 
kHz.
     Anthropogenic: Sources of ambient noise related to human 
activity include transportation (surface vessels and aircraft), 
dredging and construction, oil and gas drilling and production, seismic 
surveys, sonar, explosions, and ocean acoustic studies. Shipping noise 
typically dominates the total ambient noise for frequencies between 20 
and 300 Hz. In general, the frequencies of anthropogenic sounds are 
below 1 kHz and, if higher frequency sound levels are created, they 
attenuate rapidly (Richardson et al., 1995). Sound from identifiable 
anthropogenic sources other than the activity of interest (e.g., a 
passing vessel) is sometimes termed background sound, as opposed to 
ambient sound.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    Underwater ambient noise was measured at approximately 113 dB rms 
between 50 Hz and 20 kHz during the recent TPP project, approximately 
1.85 mi from the project area (Illingworth & Rodkin, 2012). In 2009, 
the average broadband ambient underwater noise levels were measured at 
114 dB between

[[Page 22485]]

100 Hz and 20 kHz (Slater, 2009). Peak spectral noise from industrial 
activity was noted below the 300 Hz frequency, with maximum levels of 
110 dB noted in the 125 Hz band. In the 300 Hz to 5 kHz range, average 
levels ranged between 83 and 99 dB. Wind-driven wave noise dominated 
the background noise environment at approximately 5 kHz and above, and 
ambient noise levels flattened above 10 kHz. Known sound levels and 
frequency ranges associated with anthropogenic sources similar to those 
that would be used for this project are summarized in Table 2.
    Details of the source types are described in the following text.

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

    In-water construction activities associated with the project would 
include impact pile driving and vibratory pile driving. The sounds 
produced by these activities fall into one of two general sound types: 
pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al., (2007) for an in-depth discussion of these concepts.
    Pulsed sound sources (e.g., explosions, gunshots, sonic booms, 
impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986; Harris, 1998; NIOSH, 1998; ISO, 2003; ANSI, 2005) 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 rapid decay period 
that may include a period of diminishing, oscillating maximal and 
minimal pressures, and generally have an increased capacity to induce 
physical injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems (such as 
those used by the U.S. Navy). The duration of such sounds, as received 
at a distance, can be greatly extended in a highly reverberant 
environment.
    Impact hammers operate by repeatedly dropping a heavy piston onto a 
pile to drive the pile into the substrate. Sound generated by impact 
hammers is characterized by rapid rise times and high peak levels, a 
potentially injurious combination (Hastings and Popper, 2005). 
Vibratory hammers install piles by vibrating them and allowing the 
weight of the hammer to push them into the sediment. Vibratory hammers 
produce significantly less sound than impact hammers. Peak SPLs may be 
180 dB or greater, but are generally 10 to 20 dB lower than SPLs 
generated during impact pile driving of the same-sized pile (Oestman et 
al., 2009). Rise time is slower, reducing the probability and severity 
of injury, and sound energy is distributed over a greater amount of 
time (Nedwell and Edwards, 2002; Carlson et al., 2005).

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals, 
and exposure to sound can have deleterious effects. To appropriately 
assess these potential effects, it is necessary to understand the 
frequency ranges marine mammals are able to hear. Current data indicate 
that not all marine mammal species have equal hearing capabilities 
(e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and 
Hastings, 2008). To reflect this, Southall et al. (2007) recommended 
that marine mammals be divided into functional hearing groups based on 
measured or estimated hearing ranges on the basis of available 
behavioral data, audiograms derived using auditory evoked potential 
techniques, anatomical modeling, and other data. The lower and/or upper 
frequencies for some of these functional hearing groups have been 
modified from those designated by Southall et al. (2007). The 
functional groups and the associated frequencies are indicated below 
(note that these frequency ranges do not necessarily correspond to the 
range of best hearing, which varies by species):
     Low-frequency cetaceans (mysticetes): functional hearing 
is estimated to occur between approximately 7 Hz and 30 kHz (extended 
from 22 kHz; Watkins, 1986; Au et al., 2006; Lucifredi and Stein, 2007; 
Ketten and Mountain, 2009; Tubelli et al., 2012);
     Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): functional hearing is estimated to occur 
between approximately 150 Hz and 160 kHz;
     High-frequency cetaceans (porpoises, river dolphins, and 
members of the genera Kogia and Cephalorhynchus; now considered to 
include two members of the genus Lagenorhynchus on the basis of recent 
echolocation data and genetic data [May-Collado and Agnarsson, 2006; 
Kyhn et al. 2009, 2010; Tougaard et al. 2010]): functional hearing is 
estimated to occur between approximately 200 Hz and 180 kHz; and
     Pinnipeds in water: functional hearing is estimated to 
occur between approximately 75 Hz to 100 kHz for Phocidae (true seals) 
and between 100 Hz and 40 kHz for Otariidae (eared seals), with the 
greatest sensitivity between approximately 700 Hz and 20 kHz. The 
pinniped functional hearing group was modified from Southall et al. 
(2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth et al., 
2013).

[[Page 22486]]

    There are five marine mammal species (two cetacean and three 
pinniped [two otariid and one phocid] species) with expected potential 
to co-occur with Navy construction activities. Please refer to Table 1. 
Of the two cetacean species that may be present, the killer whale is 
classified as a mid-frequency cetacean and the harbor porpoise is 
classified as a high-frequency cetacean.

Acoustic Effects, Underwater

    Potential Effects of Pile Driving Sound--The effects of sounds from 
pile driving might result in one or more of the following: temporary or 
permanent hearing impairment, non-auditory physical or physiological 
effects, behavioral disturbance, and masking (Richardson et al., 1995; 
Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007). The 
effects of pile driving on marine mammals are dependent on several 
factors, including the size, type, and depth of the animal; the depth, 
intensity, and duration of the pile driving sound; the depth of the 
water column; the substrate of the habitat; the standoff distance 
between the pile and the animal; and the sound propagation properties 
of the environment. Impacts to marine mammals from pile driving 
activities are expected to result primarily from acoustic pathways. As 
such, the degree of effect is intrinsically related to the received 
level and duration of the sound exposure, which are in turn influenced 
by the distance between the animal and the source. The further away 
from the source, the less intense the exposure should be. The substrate 
and depth of the habitat affect the sound propagation properties of the 
environment. Shallow environments are typically more structurally 
complex, which leads to rapid sound attenuation. In addition, 
substrates that are soft (e.g., sand) would absorb or attenuate the 
sound more readily than hard substrates (e.g., rock) which may reflect 
the acoustic wave. Soft porous substrates would also likely require 
less time to drive the pile, and possibly less forceful equipment, 
which would ultimately decrease the intensity of the acoustic source.
    In the absence of mitigation, impacts to marine species would be 
expected to result from physiological and behavioral responses to both 
the type and strength of the acoustic signature (Viada et al., 2008). 
The type and severity of behavioral impacts are more difficult to 
define due to limited studies addressing the behavioral effects of 
impulsive sounds on marine mammals. Potential effects from impulsive 
sound sources can range in severity from effects such as behavioral 
disturbance or tactile perception to physical discomfort, slight injury 
of the internal organs and the auditory system, or mortality (Yelverton 
et al., 1973).
    Hearing Impairment and Other Physical Effects--Marine mammals 
exposed to high intensity sound repeatedly or for prolonged periods can 
experience hearing threshold shift (TS), which is the loss of hearing 
sensitivity at certain frequency ranges (Kastak et al., 1999; Schlundt 
et al., 2000; Finneran et al., 2002, 2005). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not recoverable, or 
temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Marine mammals depend on 
acoustic cues for vital biological functions, (e.g., orientation, 
communication, finding prey, avoiding predators); thus, TTS may result 
in reduced fitness in survival and reproduction. However, this depends 
on the frequency and duration of TTS, as well as the biological context 
in which it occurs. TTS of limited duration, occurring in a frequency 
range that does not coincide with that used for recognition of 
important acoustic cues, would have little to no effect on an animal's 
fitness. Repeated sound exposure that leads to TTS could cause PTS. PTS 
constitutes injury, but TTS does not (Southall et al., 2007). The 
following subsections discuss in somewhat more detail the possibilities 
of TTS, PTS, and non-auditory physical effects.
    Temporary Threshold Shift--TTS is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing TTS, the hearing threshold rises, and a sound 
must be stronger in order to be heard. In terrestrial mammals, TTS can 
last from minutes or hours to days (in cases of strong TTS). For sound 
exposures at or somewhat above the TTS threshold, hearing sensitivity 
in both terrestrial and marine mammals recovers rapidly after exposure 
to the sound ends. Few data on sound levels and durations necessary to 
elicit mild TTS have been obtained for marine mammals, and none of the 
published data concern TTS elicited by exposure to multiple pulses of 
sound. Available data on TTS in marine mammals are summarized in 
Southall et al. (2007).
    Given the available data, the received level of a single pulse 
(with no frequency weighting) might need to be approximately 186 dB re 
1 [mu]Pa\2\-s (i.e., 186 dB sound exposure level [SEL] or approximately 
221-226 dB p-p [peak]) in order to produce brief, mild TTS. Exposure to 
several strong pulses that each have received levels near 190 dB rms 
(175-180 dB SEL) might result in cumulative exposure of approximately 
186 dB SEL and thus slight TTS in a small odontocete, assuming the TTS 
threshold is (to a first approximation) a function of the total 
received pulse energy.
    The above TTS information for odontocetes is derived from studies 
on the bottlenose dolphin (Tursiops truncatus) and beluga whale 
(Delphinapterus leucas). There is no published TTS information for 
other species of cetaceans. However, preliminary evidence from a harbor 
porpoise exposed to pulsed sound suggests that its TTS threshold may 
have been lower (Lucke et al., 2009). As summarized above, data that 
are now available imply that TTS is unlikely to occur unless 
odontocetes are exposed to pile driving pulses stronger than 180 dB re 
1 [mu]Pa rms.
    Permanent Threshold Shift--When PTS occurs, there is physical 
damage to the sound receptors in the ear. In severe cases, there can be 
total or partial deafness, while in other cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985). There is no specific evidence that exposure to pulses of sound 
can cause PTS in any marine mammal. However, given the possibility that 
mammals close to a sound source might incur TTS, there has been further 
speculation about the possibility that some individuals might incur 
PTS. Single or occasional occurrences of mild TTS are not indicative of 
permanent auditory damage, but repeated or (in some cases) single 
exposures to a level well above that causing TTS onset might elicit 
PTS.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several decibels above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time. Based on data from 
terrestrial mammals, a precautionary assumption is that the PTS 
threshold for impulse sounds (such as pile driving pulses as received 
close to the source) is at least 6 dB higher than the TTS threshold on 
a peak-pressure basis and probably greater than 6 dB (Southall et al., 
2007). On an SEL basis, Southall et al. (2007) estimated that received 
levels would need to exceed the TTS threshold by at least 15 dB for 
there to be risk of PTS. Thus, for cetaceans, Southall et al. (2007) 
estimate that the PTS threshold might be an M-

[[Page 22487]]

weighted SEL (for the sequence of received pulses) of approximately 198 
dB re 1 [mu]Pa\2\-s (15 dB higher than the TTS threshold for an 
impulse). Given the higher level of sound necessary to cause PTS as 
compared with TTS, it is considerably less likely that PTS could occur.
    Measured source levels from impact pile driving can be as high as 
214 dB rms. Although no marine mammals have been shown to experience 
TTS or PTS as a result of being exposed to pile driving activities, 
captive bottlenose dolphins and beluga whales exhibited changes in 
behavior when exposed to strong pulsed sounds (Finneran et al., 2000, 
2002, 2005). The animals tolerated high received levels of sound before 
exhibiting aversive behaviors. Experiments on a beluga whale showed 
that exposure to a single watergun impulse at a received level of 207 
kPa (30 psi) p-p, which is equivalent to 228 dB p-p, resulted in a 7 
and 6 dB TTS in the beluga whale at 0.4 and 30 kHz, respectively. 
Thresholds returned to within 2 dB of the pre-exposure level within 
four minutes of the exposure (Finneran et al., 2002). Although the 
source level of pile driving from one hammer strike is expected to be 
much lower than the single watergun impulse cited here, animals being 
exposed for a prolonged period to repeated hammer strikes could receive 
more sound exposure in terms of SEL than from the single watergun 
impulse (estimated at 188 dB re 1 [mu]Pa\2\-s) in the aforementioned 
experiment (Finneran et al., 2002). However, in order for marine 
mammals to experience TTS or PTS, the animals have to be close enough 
to be exposed to high intensity sound levels for a prolonged period of 
time. Based on the best scientific information available, these SPLs 
are far below the thresholds that could cause TTS or the onset of PTS.
    Non-auditory Physiological Effects--Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance effects, and other types of organ 
or tissue damage (Cox et al., 2006; Southall et al., 2007). Studies 
examining such effects are limited. In general, little is known about 
the potential for pile driving to cause auditory impairment or other 
physical effects in marine mammals. Available data suggest that such 
effects, if they occur at all, would presumably be limited to short 
distances from the sound source and to activities that extend over a 
prolonged period. The available data do not allow identification of a 
specific exposure level above which non-auditory effects can be 
expected (Southall et al., 2007) or any meaningful quantitative 
predictions of the numbers (if any) of marine mammals that might be 
affected in those ways. Marine mammals that show behavioral avoidance 
of pile driving, including some odontocetes and some pinnipeds, are 
especially unlikely to incur auditory impairment or non-auditory 
physical effects.

Disturbance Reactions

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

Auditory Masking

    Natural and artificial sounds can disrupt behavior by masking, or 
interfering with, a marine mammal's ability to hear other sounds. 
Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher levels. Chronic exposure to excessive, though not high-
intensity, sound could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions. 
Masking can interfere with detection of acoustic signals such as 
communication calls, echolocation sounds, and environmental sounds 
important to marine mammals. Therefore, under certain circumstances, 
marine mammals

[[Page 22488]]

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

Acoustic Effects, Airborne

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

Anticipated Effects on Habitat

    The proposed activities at NBKB would not result in permanent 
impacts to habitats used directly by marine mammals, such as haul-out 
sites, but may have potential short-term impacts to food sources such 
as forage fish and salmonids. There are no rookeries or major haul-out 
sites within 16 km or ocean bottom structure of significant biological 
importance to marine mammals that may be present in the marine waters 
in the vicinity of the project area. Therefore, the main impact 
associated with the proposed activity would be temporarily elevated 
sound levels and the associated direct effects on marine mammals, as 
discussed previously in this document. The most likely impact to marine 
mammal habitat occurs from pile driving effects on likely marine mammal 
prey (i.e., fish) near NBKB and minor impacts to the immediate 
substrate during installation and removal of piles during the wharf 
maintenance project.

Pile Driving Effects on Potential Prey

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

Pile Driving Effects on Potential Foraging Habitat

    The area likely impacted by the project is relatively small 
compared to the available habitat in the Hood Canal. Avoidance by 
potential prey (i.e., fish) of the immediate area due to the temporary 
loss of this foraging habitat is also possible. The duration of fish

[[Page 22489]]

avoidance of this area after pile driving stops is unknown, but a rapid 
return to normal recruitment, distribution and behavior is anticipated. 
Any behavioral avoidance by fish of the disturbed area would still 
leave significantly large areas of fish and marine mammal foraging 
habitat in the Hood Canal and nearby vicinity.
    In summary, given the short daily duration of sound associated with 
individual pile driving events and the relatively small areas being 
affected, pile driving activities associated with the proposed action 
are not likely to have a permanent, adverse effect on any fish habitat, 
or populations of fish species. Thus, any impacts to marine mammal 
habitat are not expected to cause significant or long-term consequences 
for individual marine mammals or their populations.

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses.
    Measurements from similar pile driving events, including from 
previously monitored construction activity on the NBKB waterfront, were 
coupled with practical spreading loss to estimate zones of influence 
(ZOI; see ``Estimated Take by Incidental Harassment''). These values 
were then used to develop mitigation measures for EHW-1 pile driving 
activities. The ZOIs effectively represent the mitigation zone that 
would be established around each pile to prevent Level A harassment to 
marine mammals, while providing estimates of the areas within which 
Level B harassment might occur. While the ZOIs vary between the 
different diameter piles and types of installation methods, the Navy is 
proposing to establish mitigation zones for the maximum ZOI for all 
pile driving conducted in support of the wharf maintenance project. In 
addition to the measures described later in this section, the Navy 
would conduct briefings between construction supervisors and crews, 
marine mammal monitoring team, and Navy staff prior to the start of all 
pile driving activity, and when new personnel join the work, in order 
to explain responsibilities, communication procedures, marine mammal 
monitoring protocol, and operational procedures.

Monitoring and Shutdown for Pile Driving

    The following measures would apply to the Navy's mitigation through 
shutdown and disturbance zones:
    Shutdown Zone--For all pile driving activities, the Navy will 
establish a shutdown zone intended to contain the area in which SPLs 
equal or exceed the 180/190 dB rms acoustic injury criteria. The 
purpose of a shutdown zone is to define an area within which shutdown 
of activity would occur upon sighting of a marine mammal (or in 
anticipation of an animal entering the defined area), thus preventing 
injury of marine mammals. Modeled distances for shutdown zones are 
shown in Table 4. The Navy would implement a minimum shutdown zone of 
29 m radius for cetaceans and 10 m radius for pinnipeds around all pile 
driving activity. However, no cetaceans have been observed within the 
floating port security barrier, which is approximately 500 m from the 
wharf.
    Disturbance Zone--Disturbance zones are the areas in which SPLs 
equal or exceed 160 and 120 dB rms (for pulsed and non-pulsed 
continuous sound, respectively). Disturbance zones provide utility for 
monitoring conducted for mitigation purposes (i.e., shutdown zone 
monitoring) by establishing monitoring protocols for areas adjacent to 
the shutdown zones. Monitoring of disturbance zones enables observers 
to be aware of and communicate the presence of marine mammals in the 
project area but outside the shutdown zone and thus prepare for 
potential shutdowns of activity. However, the primary purpose of 
disturbance zone monitoring is for documenting incidents of Level B 
harassment; disturbance zone monitoring is discussed in greater detail 
later (see ``Proposed Monitoring and Reporting''). Nominal radial 
distances for disturbance zones are shown in Table 4. Given the size of 
the disturbance zone for vibratory pile driving, it is impossible to 
guarantee that all animals would be observed or to make comprehensive 
observations of fine-scale behavioral reactions to sound, and only a 
portion of the zone (e.g., what may be reasonably observed by visual 
observers stationed within the water front restricted area [WRA]) will 
be monitored.
    In order to document observed incidents of harassment, monitors 
record all marine mammal observations, regardless of location. The 
observer's location, as well as the location of the pile being driven, 
is known from a GPS. The location of the animal is estimated as a 
distance from the observer, which is then compared to the location from 
the pile. The received level may be estimated on the basis of past or 
subsequent acoustic monitoring. It may then be determined whether the 
animal was exposed to sound levels constituting incidental harassment 
in post-processing of observational data, and a precise accounting of 
observed incidents of harassment created. Therefore, although the 
predicted distances to behavioral harassment thresholds are useful for 
estimating harassment for purposes of authorizing levels of incidental 
take, actual take may be determined in part through the use of 
empirical data. That information may then be used to extrapolate 
observed takes to reach an approximate understanding of actual total 
takes.
    Monitoring Protocols--Monitoring would be conducted before, during, 
and after pile driving activities. In addition, observers shall record 
all incidents of marine mammal occurrence, regardless of distance from 
activity, and shall document any behavioral reactions in concert with 
distance from piles being driven. Observations made outside the 
shutdown zone will not result in shutdown; that pile segment would be 
completed without cessation, unless the animal approaches or enters the 
shutdown zone, at which point all pile driving activities would be 
halted. Monitoring will take place from fifteen minutes prior to 
initiation through thirty minutes post-completion of pile driving 
activities. Pile driving activities include the time to remove a single 
pile or series of piles, as long as the time elapsed between uses of 
the pile driving equipment is no more than thirty minutes. Please see 
the Marine Mammal Monitoring Plan (available at www.nmfs.noaa.gov/pr/permits/incidental/ and as Appendix C of the Navy's application), 
developed by the Navy with our approval, for full details of the 
monitoring protocols.
    The following additional measures apply to visual monitoring:
    (1) Monitoring will be conducted by qualified observers, who will 
be placed at the best vantage point(s) practicable to monitor for 
marine mammals and implement shutdown/delay procedures when applicable 
by calling for the shutdown to the hammer operator. Qualified observers 
are trained biologists, with the following minimum qualifications:
     Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target;

[[Page 22490]]

     Advanced education in biological science or related field 
(undergraduate degree or higher required);
     Experience and ability to conduct field observations and 
collect data according to assigned protocols (this may include academic 
experience);
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates and times when in-water construction 
activities were suspended to avoid potential incidental injury from 
construction sound of marine mammals observed within a defined shutdown 
zone; and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    (2) Prior to the start of pile driving activity, the shutdown zone 
will be monitored for fifteen minutes to ensure that it is clear of 
marine mammals. Pile driving will only commence once observers have 
declared the shutdown zone clear of marine mammals; animals will be 
allowed to remain in the shutdown zone (i.e., must leave of their own 
volition) and their behavior will be monitored and documented. The 
shutdown zone may only be declared clear, and pile driving started, 
when the entire shutdown zone is visible (i.e., when not obscured by 
dark, rain, fog, etc.). In addition, if such conditions should arise 
during impact pile driving that is already underway, the activity would 
be halted.
    (3) If a marine mammal approaches or enters the shutdown zone 
during the course of pile driving operations, activity will be halted 
and delayed until either the animal has voluntarily left and been 
visually confirmed beyond the shutdown zone or fifteen minutes have 
passed without re-detection of the animal. Monitoring will be conducted 
throughout the time required to drive a pile.

Sound Attenuation Devices

    Sound levels can be greatly reduced during impact pile driving 
using sound attenuation devices. There are several types of sound 
attenuation devices including bubble curtains, cofferdams, and 
isolation casings (also called temporary noise attenuation piles 
[TNAP]), and cushion blocks. The Navy proposes to use bubble curtains, 
which create a column of air bubbles rising around a pile from the 
substrate to the water surface. The air bubbles absorb and scatter 
sound waves emanating from the pile, thereby reducing the sound energy. 
Bubble curtains may be confined or unconfined. An unconfined bubble 
curtain may consist of a ring seated on the substrate and emitting air 
bubbles from the bottom. An unconfined bubble curtain may also consist 
of a stacked system, that is, a series of multiple rings placed at the 
bottom and at various elevations around the pile. Stacked systems may 
be more effective than non-stacked systems in areas with high current 
and deep water (Oestman et al., 2009).
    A confined bubble curtain contains the air bubbles within a 
flexible or rigid sleeve made from plastic, cloth, or pipe. Confined 
bubble curtains generally offer higher attenuation levels than 
unconfined curtains because they may physically block sound waves and 
they prevent air bubbles from migrating away from the pile. For this 
reason, the confined bubble curtain is commonly used in areas with high 
current velocity (Oestman et al., 2009).
    Both environmental conditions and the characteristics of the sound 
attenuation device may influence the effectiveness of the device. 
According to Oestman et al. (2009):
     In general, confined bubble curtains attain better sound 
attenuation levels in areas of high current than unconfined bubble 
curtains. If an unconfined device is used, high current velocity may 
sweep bubbles away from the pile, resulting in reduced levels of sound 
attenuation.
     Softer substrates may allow for a better seal for the 
device, preventing leakage of air bubbles and escape of sound waves. 
This increases the effectiveness of the device. Softer substrates also 
provide additional attenuation of sound traveling through the 
substrate.
     Flat bottom topography provides a better seal, enhancing 
effectiveness of the sound attenuation device, whereas sloped or 
undulating terrain reduces or eliminates its effectiveness.
     Air bubbles must be close to the pile; otherwise, sound 
may propagate into the water, reducing the effectiveness of the device.
     Harder substrates may transmit ground-borne sound and 
propagate it into the water column.
    The literature presents a wide array of observed attenuation 
results for bubble curtains (e.g., Oestman et al., 2009; Coleman, 2011; 
see Appendix B of the Navy's application). The variability in 
attenuation levels is due to variation in design, as well as 
differences in site conditions and difficulty in properly installing 
and operating in-water attenuation devices. As a general rule, 
reductions of greater than 10 dB cannot be reliably predicted. The TPP 
reported a range of measured values for realized attenuation mostly 
within 6 to 12 dB (Illingworth & Rodkin, 2012). For 36-in piles the 
average peak and rms reduction with use of the bubble curtain was 8 dB, 
where the averages of all bubble-on and bubble-off data were compared. 
For 48-in piles, the average SPL reduction with use of a bubble curtain 
was 6 dB for average peak values and 5 dB for rms values.
    To avoid loss of attenuation from design and implementation errors, 
the Navy has required specific bubble curtain design specifications, 
including testing requirements for air pressure and flow prior to 
initial impact hammer use, and a requirement for placement on the 
substrate. We considered TPP measurements (approximately 7 dB overall) 
and other monitored projects (typically at least 8 dB realized 
attenuation), and consider 8 dB as potentially a reasonable estimate of 
average SPL (rms) reduction, assuming appropriate deployment and no 
problems with the equipment.
    Bubble curtains shall be used during all impact pile driving. The 
device will distribute air bubbles around one hundred percent of the 
piling perimeter for the full depth of the water column, and the lowest 
bubble ring shall be in contact with the mudline for the full 
circumference of the ring. Testing of the device by comparing 
attenuated and unattenuated strikes is not possible because of 
requirements in place to protect marbled murrelets (an ESA-listed bird 
species under the jurisdiction of the USFWS). However, in order to 
avoid loss of attenuation from design and implementation errors in the 
absence of such testing, a performance test of the device shall be 
conducted prior to initial use. The performance test shall confirm the 
calculated pressures and flow rates at each manifold ring. In addition, 
the contractor shall also train personnel in the proper balancing of 
air flow to the bubblers and shall submit an inspection/performance 
report to the Navy within 72 hours following the performance test.

[[Page 22491]]

Timing Restrictions

    In Hood Canal, designated timing restrictions exist for pile 
driving activities to avoid in-water work when salmonids and other 
spawning forage fish are likely to be present. The in-water work window 
is July 16-January 15. Until September 23, impact pile driving will 
only occur starting two hours after sunrise and ending two hours before 
sunset due to marbled murrelet nesting season. After September 23, in-
water construction activities will occur during daylight hours (sunrise 
to sunset).

Soft Start

    The use of a soft-start procedure is believed to provide additional 
protection to marine mammals by warning or providing a chance to leave 
the area prior to the hammer operating at full capacity, and typically 
involves a requirement to initiate sound from vibratory hammers for 
fifteen seconds at reduced energy followed by a thirty-second waiting 
period. This procedure is repeated two additional times.
    However, implementation of soft start for vibratory pile driving 
during previous pile driving work for the EHW-2 project at NBKB has led 
to equipment failure and serious human safety concerns. Project staff 
have reported that, during power down from the soft start, the energy 
from the hammer is transferred to the crane boom and block via the load 
fall cables and rigging resulting in unexpected damage to both the 
crane block and crane boom. This differs from what occurs when the 
hammer is powered down after a pile is driven to refusal in that the 
rigging and load fall cables are able to be slacked prior to powering 
down the hammer, and the vibrations are transferred into the substrate 
via the pile rather than into the equipment via the rigging. One 
dangerous incident of equipment failure has already occurred, with a 
portion of the equipment shearing from the crane and falling to the 
deck. Subsequently, the crane manufacturer has inspected the crane 
booms and discovered structural fatigue in the boom lacing and main 
structural components, which will ultimately result in a collapse of 
the crane boom. All cranes were new at the beginning of the job. In 
addition, the vibratory hammer manufacturer has attempted to install 
dampers to mitigate the problem, without success. In consultation with 
the Navy and experts in the field of marine construction, it was 
determined that the likely cause of the issue was that larger vibratory 
hammers (e.g., APE Model 600) are not designed to handle the additional 
vibration resulting from the soft start procedure. Large hammers were 
required due to the design specifications of the EHW-2, but are not 
expected to be necessary for the EHW-1 maintenance work. Use of smaller 
variable moment style vibratory hammers has not resulted in similar 
issues to date.
    Therefore, vibratory soft start will be required as previously 
described. However, if a variable moment hammer proves infeasible for 
use with this project, or if unsafe working conditions during soft 
starts are reported by the contractor and verified by an independent 
safety inspection, the Navy may discontinue use of the vibratory soft 
start measure.
    For impact driving, soft start will be required, and contractors 
will provide an initial set of strikes from the impact hammer at 
reduced energy, followed by a thirty-second waiting period, then two 
subsequent reduced energy strike sets. The reduced energy of an 
individual hammer cannot be quantified because of variation in 
individual drivers. The actual number of strikes at reduced energy will 
vary because operating the hammer at less than full power results in 
``bouncing'' of the hammer as it strikes the pile, resulting in 
multiple ``strikes.'' Soft start for impact driving will be required at 
the beginning of each day's pile driving work and at any time following 
a cessation of impact pile driving of thirty minutes or longer.
    We have carefully evaluated the Navy's proposed mitigation measures 
and considered their effectiveness in past implementation to 
preliminarily determine whether they are likely to effect the least 
practicable impact on the affected marine mammal species and stocks and 
their habitat. Our evaluation of potential measures included 
consideration of the following factors in relation to one another: (1) 
The manner in which, and the degree to which, the successful 
implementation of the measure is expected to minimize adverse impacts 
to marine mammals, (2) the proven or likely efficacy of the specific 
measure to minimize adverse impacts as planned; and (3) the 
practicability of the measure for applicant implementation.
    Any mitigation measure(s) we prescribe should be able to 
accomplish, have a reasonable likelihood of accomplishing (based on 
current science), or contribute to the accomplishment of one or more of 
the general goals listed below:
    (1) Avoidance or minimization of injury or death of marine mammals 
wherever possible (goals 2, 3, and 4 may contribute to this goal).
    (2) A reduction in the number (total number or number at 
biologically important time or location) of individual marine mammals 
exposed to stimuli expected to result in incidental take (this goal may 
contribute to 1, above, or to reducing takes by behavioral harassment 
only).
    (3) A reduction in the number (total number or number at 
biologically important time or location) of times any individual marine 
mammal would be exposed to stimuli expected to result in incidental 
take (this goal may contribute to 1, above, or to reducing takes by 
behavioral harassment only).
    (4) A reduction in the intensity of exposure to stimuli expected to 
result in incidental take (this goal may contribute to 1, above, or to 
reducing the severity of behavioral harassment only).
    (5) Avoidance or minimization of adverse effects to marine mammal 
habitat, paying particular attention to the prey base, blockage or 
limitation of passage to or from biologically important areas, 
permanent destruction of habitat, or temporary disturbance of habitat 
during a biologically important time.
    (6) For monitoring directly related to mitigation, an increase in 
the probability of detecting marine mammals, thus allowing for more 
effective implementation of the mitigation.
    Based on our evaluation of the Navy's proposed measures, including 
information from monitoring of the Navy's implementation of the 
mitigation measures as prescribed under previous IHAs for this and 
other projects in the Hood Canal, we have preliminarily determined that 
the proposed mitigation measures provide the means of effecting the 
least practicable impact on marine mammal species or stocks and their 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth ``requirements pertaining to 
the monitoring and reporting of such taking''. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that requests for 
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.

[[Page 22492]]

    Any monitoring requirement we prescribe should accomplish one or 
more of the following general goals:
    1. An increase in the probability of detecting marine mammals, both 
within defined zones of effect (thus allowing for more effective 
implementation of the mitigation) and in general to generate more data 
to contribute to the analyses mentioned below;
    2. An increase in our understanding of how many marine mammals are 
likely to be exposed to stimuli that we associate with specific adverse 
effects, such as behavioral harassment or hearing threshold shifts;
    3. An increase in our understanding of how marine mammals respond 
to stimuli expected to result in incidental take and how anticipated 
adverse effects on individuals may impact the population, stock, or 
species (specifically through effects on annual rates of recruitment or 
survival) through any of the following methods:
     Behavioral observations in the presence of stimuli 
compared to observations in the absence of stimuli (need to be able to 
accurately predict pertinent information, e.g., received level, 
distance from source);
     Physiological measurements in the presence of stimuli 
compared to observations in the absence of stimuli (need to be able to 
accurately predict pertinent information, e.g., received level, 
distance from source);
     Distribution and/or abundance comparisons in times or 
areas with concentrated stimuli versus times or areas without stimuli;
    4. An increased knowledge of the affected species; or
    5. An increase in our understanding of the effectiveness of certain 
mitigation and monitoring measures.
    The Navy submitted a marine mammal monitoring plan as part of their 
IHA application, and can be found on the Internet at www.nmfs.noaa.gov/pr/permits/incidental/. Similar plans have been successfully 
implemented by the Navy under previous IHAs issued for work conducted 
at NBKB and the plan may be modified or supplemented based on comments 
or new information received from the public during the public comment 
period.

Visual Marine Mammal Observations

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

Data Collection

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

Reporting

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

Estimated Take by Incidental Harassment

    Except with respect to certain activities not pertinent here, 
section 3(18) of the MMPA defines ``harassment'' as: ``. . . any act of 
pursuit, torment, or annoyance which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild [Level A harassment]; 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering [Level B harassment].''
    All anticipated takes would be by Level B harassment resulting from 
vibratory and impact pile driving and involving temporary changes in 
behavior. The proposed mitigation and monitoring measures are expected 
to minimize the possibility of injurious or

[[Page 22493]]

lethal takes such that take by Level A harassment, serious injury, or 
mortality is considered discountable. However, it is unlikely that 
injurious or lethal takes would occur even in the absence of the 
planned mitigation and monitoring measures.
    If a marine mammal responds to a stimulus by changing its behavior 
(e.g., through relatively minor changes in locomotion direction/speed 
or vocalization behavior), the response may or may not constitute 
taking at the individual level, and is unlikely to affect the stock or 
the species as a whole. However, if a sound source displaces marine 
mammals from an important feeding or breeding area for a prolonged 
period, impacts on animals or on the stock or species could potentially 
be significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007). Given 
the many uncertainties in predicting the quantity and types of impacts 
of sound on marine mammals, it is common practice to estimate how many 
animals are likely to be present within a particular distance of a 
given activity, or exposed to a particular level of sound.
    This practice potentially overestimates the numbers of marine 
mammals taken. For example, during the past fifteen years, killer 
whales have been observed within the project area twice. On the basis 
of that information, an estimated amount of potential takes for killer 
whales is presented here. However, while a pod of killer whales could 
potentially visit again during the project timeframe, and thus be 
taken, it is more likely that they will not. Although incidental take 
of killer whales has been authorized under past IHAs for activities at 
NBKB on the basis of past observations of these species, no such takes 
have been recorded and no individuals of these species have been 
observed. Similarly, estimated actual take levels (observed takes 
extrapolated to the remainder of unobserved but ensonified area) were 
significantly less than authorized levels of take for the remaining 
species. In addition, it is often difficult to distinguish between the 
individuals harassed and incidences of harassment. In particular, for 
stationary activities, it is more likely that some smaller number of 
individuals may accrue a number of incidences of harassment per 
individual than for each incidence to accrue to a new individual, 
especially if those individuals display some degree of residency or 
site fidelity and the impetus to use the site (e.g., because of 
foraging opportunities) is stronger than the deterrence presented by 
the harassing activity.
    The project area is not believed to be particularly important 
habitat for marine mammals, nor is it considered an area frequented by 
marine mammals, although harbor seals are year-round residents of Hood 
Canal and sea lions are known to haul-out on submarines and other man-
made objects at the NBKB waterfront (although typically at a distance 
of a mile or greater from the project site). Therefore, behavioral 
disturbances that could result from anthropogenic sound associated with 
these activities are expected to affect only a relatively small number 
of individual marine mammals, although those effects could be recurring 
over the life of the project if the same individuals remain in the 
project vicinity.
    The Navy has requested authorization for the incidental taking of 
small numbers of Steller sea lions, California sea lions, harbor seals, 
transient killer whales, and harbor porpoises in the Hood Canal that 
may result from pile driving during construction activities associated 
with the wharf maintenance project described previously in this 
document. In order to estimate the potential incidents of take that may 
occur incidental to the specified activity, we must first estimate the 
extent of the sound field that may be produced by the activity and then 
consider in combination with information about marine mammal density or 
abundance in the project area. We first provide information on 
applicable sound thresholds for determining effects to marine mammals 
before describing the information used in estimating the sound fields, 
the available marine mammal density or abundance information, and the 
method of estimating potential incidences of take.

Sound Thresholds

    We use generic sound exposure thresholds to determine when an 
activity that produces sound might result in impacts to a marine mammal 
such that a take by harassment might occur. To date, no studies have 
been conducted that explicitly examine impacts to marine mammals from 
pile driving sounds or from which empirical sound thresholds have been 
established. These thresholds should be considered guidelines for 
estimating when harassment may occur (i.e., when an animal is exposed 
to levels equal to or exceeding the relevant criterion) in specific 
contexts; however, useful contextual information that may inform our 
assessment of effects is typically lacking and we consider these 
thresholds as step functions. NMFS is currently revising these acoustic 
guidelines; for more information on that process, please visit 
www.nmfs.noaa.gov/pr/acoustics/guidelines.htm. Vibratory pile driving 
produces non-pulsed noise and impact pile driving produces impulsive 
noise.

               Table 3--Current Acoustic Exposure Criteria
------------------------------------------------------------------------
            Criterion                 Definition           Threshold
------------------------------------------------------------------------
Level A harassment (underwater).  Injury (PTS--any    180 dB (cetaceans)/
                                   level above that    190 dB
                                   which is known to   (pinnipeds)
                                   cause TTS).         (rms).
Level B harassment (underwater).  Behavioral          160 dB (impulsive
                                   disruption.         source)/120 dB
                                                       (continuous
                                                       source) (rms).
Level B harassment (airborne)*..  Behavioral          90 dB (harbor
                                   disruption.         seals)/100 dB
                                                       (other pinnipeds)
                                                       (unweighted).
------------------------------------------------------------------------
* NMFS has not established any formal criteria for harassment resulting
  from exposure to airborne sound. However, these thresholds represent
  the best available information regarding the effects of pinniped
  exposure to such sound and NMFS' practice is to associate exposure at
  these levels with Level B harassment.

Distance to Sound Thresholds

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


[[Page 22494]]


TL = B * log10(R1/R2), where
R1 = the distance of the modeled SPL from the driven pile, 
and
R2 = the distance from the driven pile of the initial 
measurement.

    This formula neglects loss due to scattering and absorption, which 
is assumed to be zero here. The degree to which underwater sound 
propagates away from a sound source is dependent on a variety of 
factors, most notably the water bathymetry and presence or absence of 
reflective or absorptive conditions including in-water structures and 
sediments. Spherical spreading occurs in a perfectly unobstructed 
(free-field) environment not limited by depth or water surface, 
resulting in a 6 dB reduction in sound level for each doubling of 
distance from the source (20*log[range]). Cylindrical spreading occurs 
in an environment in which sound propagation is bounded by the water 
surface and sea bottom, resulting in a reduction of 3 dB in sound level 
for each doubling of distance from the source (10*log[range]). A 
practical spreading value of fifteen is often used under conditions, 
such as Hood Canal, where water increases with depth as the receiver 
moves away from the shoreline, resulting in an expected propagation 
environment that would lie between spherical and cylindrical spreading 
loss conditions. Practical spreading loss (4.5 dB reduction in sound 
level for each doubling of distance) is assumed here.
    Underwater Sound--The intensity of pile driving sounds is greatly 
influenced by factors such as the type of piles, hammers, and the 
physical environment in which the activity takes place. A large 
quantity of literature regarding SPLs recorded from pile driving 
projects is available for consideration. In order to determine 
reasonable SPLs and their associated effects on marine mammals that are 
likely to result from pile driving at NBKB, studies with similar 
properties to the specified activity were evaluated, including 
measurements conducted for driving of steel piles at NBKB as part of 
the TPP (Illingworth & Rodkin, 2012). Please see Appendix B of the 
Navy's application for a detailed description of the information 
considered in determining reasonable proxy source level values. The 
Navy used representative source levels (for installation of 30-in steel 
pipe pile) of 195 dB rms for impact driving and 166 dB rms for 
vibratory driving. For impact driving, 8 dB effective attenuation was 
assumed due to use of a bubble curtain and was therefore subtracted 
from the source level.
    We assume here that consideration of vibratory pile driving, and 
that vibratory driving could occur on any of the eight days, is 
conservative in relation to pile removal via pneumatic chipping. 
Acoustic measurements for pneumatic chipping were previously performed 
during maintenance work at EHW-1 in 2012. The average value measured at 
10 m was 141 dB rms (RMDT, 2013). Therefore, we do not explicitly 
consider pile removal (via pneumatic chipping) separately from pile 
installation activity.

  Table 4--Calculated Distance(s) to and Area Encompassed by Underwater
         Marine Mammal Sound Thresholds During Pile Installation
------------------------------------------------------------------------
            Threshold                  Distance              Area
------------------------------------------------------------------------
Impact driving, pinniped injury   6 m...............  113 m\2\
 (190 dB).
Impact driving, cetacean injury   29 m..............  2,630 m\2\
 (180 dB).
Impact driving, disturbance (160  631 m.............  0.9 km\2\
 dB).
Vibratory driving, pinniped       n/a...............  --
 injury (190 dB).
Vibratory driving, cetacean       n/a...............  --
 injury (180 dB).
Vibratory driving, disturbance    6.3 km............  32.4 km\2\
 (120 dB).
------------------------------------------------------------------------

    Hood Canal does not represent open water, or free field, 
conditions. Therefore, sounds would attenuate as they encounter land 
masses or bends in the canal. As a result, the calculated distance and 
areas of impact for the 120-dB threshold cannot actually be attained at 
the project area. See Figure 6-1 of the Navy's application for a 
depiction of the size of areas in which each underwater sound threshold 
is predicted to occur at the project area due to pile driving.
    Airborne Sound--Pile driving can generate airborne sound that could 
potentially result in disturbance to marine mammals (specifically, 
pinnipeds) which are hauled out or at the water's surface. As a result, 
the Navy analyzed the potential for pinnipeds hauled out or swimming at 
the surface near NBKB to be exposed to airborne SPLs that could result 
in Level B behavioral harassment. A spherical spreading loss model 
(i.e., 6 dB reduction in sound level for each doubling of distance from 
the source), in which there is a perfectly unobstructed (free-field) 
environment not limited by depth or water surface, is appropriate for 
use with airborne sound and was used to estimate the distance to the 
airborne thresholds.
    As was discussed for underwater sound from pile driving, the 
intensity of pile driving sounds is greatly influenced by factors such 
as the type of piles, hammers, and the physical environment in which 
the activity takes place. In order to determine reasonable airborne 
SPLs and their associated effects on marine mammals that are likely to 
result from pile driving at NBKB, studies with similar properties to 
the proposed action, as described previously, were evaluated. The Navy 
used representative source levels of 112 dB Lmax 
(unweighted) for impact driving (for 36-in steel pipe piles) and 95 dB 
Lmax (unweighted) for vibratory driving (for 30-in steel 
pipe piles). Please see Appendix B of the Navy's application for 
details of the information considered. These values give a maximum 
disturbance zone (radial distance) of 189 m for harbor seals and 60 m 
for sea lions (see Table 6-6 in the Navy's application).
    However, no incidents of incidental take resulting solely from 
airborne sound are likely, as distances to the harassment thresholds 
would not reach areas where pinnipeds may haul out. Harbor seals can 
haul out at a variety of natural or manmade locations, but the closest 
known harbor seal haul-out is at the Dosewallips River mouth (London, 
2006) and Navy waterfront surveys and boat surveys have found it rare 
for harbor seals to haul out along the NBKB waterfront (Agness and 
Tannenbaum, 2009; Tannenbaum et al., 2009, 2011; DoN, 2013). Individual 
seals have been observed hauled out on pontoons of the floating 
security fence within the restricted areas of NBKB, but this area is 
not within the airborne disturbance ZOI. Nearby piers are elevated well 
above the surface of the water and are inaccessible to pinnipeds, and 
seals have not been observed hauled out on the adjacent shoreline. Sea 
lions typically haul out on submarines docked at Delta Pier, 
approximately one mile from the project site.
    We recognize that pinnipeds in the water could be exposed to 
airborne sound that may result in behavioral harassment when looking 
with heads above water. However, these animals would previously have 
been `taken' as a result of exposure to underwater sound above the 
behavioral harassment thresholds, which are in all cases larger than 
those associated with airborne sound. Thus, the behavioral harassment 
of these animals is already accounted for in these estimates of 
potential take. Multiple incidents of exposure to sound above NMFS' 
thresholds for behavioral harassment are not believed to result in 
increased behavioral disturbance, in either nature or intensity of 
disturbance reaction. Therefore, we do not believe that authorization 
of incidental take resulting from airborne sound for

[[Page 22495]]

pinnipeds is warranted, and airborne sound is not discussed further 
here.

Marine Mammal Occurrence

    The Navy has developed, with input from regional marine mammal 
experts, estimates of marine mammal densities in Washington inland 
waters for the Navy Marine Species Density Database (NMSDD). A 
technical report (Hanser et al., 2014) describes methodologies and 
available information used to derive these densities, which are 
generally considered the best available information for Washington 
inland waters, except where specific local abundance information is 
available. With the exception of the harbor porpoise density (derived 
from vessel-based surveys conducted in Hood Canal), we do not believe 
the NMSDD density values are appropriate for use here, for the 
following reasons: (1) Local abundance information exists for sea 
lions, which regularly haul out at the NBKB waterfront; (2) harbor seal 
density for Hood Canal has recently been revised as described below; 
and (3) density values are not appropriate for rarely occurring 
species, such as transient killer whales in Hood Canal. Please see 
Appendix A of the Navy's application for more information about survey 
effort at NBKB.
    For all species, the most appropriate information available was 
used to estimate the number of potential incidences of take. For harbor 
seals, this involved published literature describing harbor seal 
research conducted in Washington and Oregon, including counts and 
research specific to Hood Canal (Huber et al., 2001; Jeffries et al., 
2003; London et al., 2012). Killer whales are known from two periods of 
occurrence (2003 and 2005) and are not known to preferentially use any 
specific portion of the Hood Canal. Therefore, potential occurrence was 
assumed as likely maximum group size (Houghton et al., in prep.) in 
concert with a nominal number of days present, in order to provide for 
small possibility that killer whales could be present. The best 
information available for the remaining species in Hood Canal came from 
surveys conducted by the Navy at the NBKB waterfront or in the vicinity 
of the project area (see Appendix A of the Navy's application).
    Due to their occurrence in deeper waters of Hood Canal, this 
analysis assumes that harbor porpoise are uniformly distributed in the 
project area. However, it should be noted that there have been no 
observations of cetaceans within the floating security barriers at 
NBKB; these barriers thus appear to effectively prevent cetaceans from 
approaching the shutdown zones. Although the Navy will implement a 
precautionary shutdown zone for cetaceans, anecdotal evidence suggests 
that cetaceans are not at risk of Level A harassment at NBKB even from 
louder activities (e.g., impact pile driving). As described previously, 
any potential occurrence of killer whales would be a rare event likely 
consisting of a single group of whales. Harbor seals likely occur in 
greater numbers of along the NBKB waterfront than in deeper waters of 
Hood Canal, but are observed throughout the action area and through use 
of a density value here we assume that they are uniformly distributed 
(likely overestimating occurrence in the larger Level B harassment zone 
for vibratory driving). The remaining species that occur in the project 
area, Steller sea lion and California sea lion, do not appear to 
utilize most of Hood Canal. The sea lions appear to be attracted to the 
man-made haul-out opportunities along the NBKB waterfront while 
dispersing for foraging opportunities elsewhere in Hood Canal. 
California sea lions were not reported during aerial surveys of Hood 
Canal (Jeffries et al., 2000), and Steller sea lions have been 
documented almost solely at the NBKB waterfront.

Description of Take Calculation

    The take calculations presented here rely on the best data 
currently available for marine mammal populations in the Hood Canal. 
The formula was developed for calculating take due to pile driving 
activity and applied to each group-specific sound impact threshold. The 
formula is founded on the following assumptions:
     All marine mammal individuals potentially available are 
assumed to be present within the relevant area, and thus incidentally 
taken;
     An individual can only be taken once during a 24-h period;
     There were will be eight total days of activity and the 
largest ZOI equals 32.4 km\2\;
     Exposure modeling assumes that one impact pile driver and 
three vibratory pile drivers are operating concurrently; and,
     Exposures to sound levels above the relevant thresholds 
equate to take, as defined by the MMPA.
    The calculation for marine mammal takes is estimated by:
    Exposure estimate = (n * ZOI) * days of total activity

Where:

n = density estimate used for each species/season
ZOI = sound threshold ZOI area; the area encompassed by all 
locations where the SPLs equal or exceed the threshold being 
evaluated

    n * ZOI produces an estimate of the abundance of animals that could 
be present in the area for exposure, and is rounded to the nearest 
whole number before multiplying by days of total activity. Where simple 
abundance is used, this value replaces the product of n * ZOI.
    The ZOI impact area is the estimated range of impact to the sound 
criteria. The relevant distances specified in Table 4 were used to 
calculate ZOIs around each pile. The ZOI impact area took into 
consideration the possible affected area of the Hood Canal from the 
pile driving site furthest from shore with attenuation due to land 
shadowing from bends in the canal. Because of the close proximity of 
some of the piles to the shore, the narrowness of the canal at the 
project area, and the maximum fetch, the ZOIs for each threshold are 
not necessarily spherical and may be truncated.
    While pile driving can occur any day throughout the in-water work 
window, and the analysis is conducted on a per day basis, only a 
fraction of that time (typically a matter of hours on any given day) is 
actually spent pile driving. Also of note is the fact that the 
effectiveness of mitigation measures in reducing takes is typically not 
quantified in the take estimation process. In addition, equating 
exposure with response (i.e., a behavioral response meeting the 
definition of take under the MMPA) is a simplistic and conservative 
assumption. For these reasons, these take estimates are likely to be 
conservative. See Table 5 for total estimated incidents of take.
    California Sea Lion--California sea lions occur regularly in the 
vicinity of the project site, with the exception of approximately mid-
June through mid-August, as determined by Navy waterfront surveys 
conducted from April 2008 through December 2013. The first California 
sea lion was observed at NBKB in August 2009, and their occurrence has 
been increasing since that time (DoN, 2013). With regard to the range 
of this species in Hood Canal and the project area, we assume on the 
basis of waterfront observations (Agness and Tannenbaum, 2009; 
Tannenbaum et al., 2009, 2011; HDR 2012a, 2012b; Hart Crowser, 2013) 
that the opportunity to haul out on submarines docked at Delta Pier is 
a primary attractant for California sea lions in Hood Canal, as they 
are not typically observed elsewhere in Hood Canal. Abundance is 
calculated as the monthly average of the maximum number observed in a 
given month, as

[[Page 22496]]

opposed to the overall average. That is, the maximum number of animals 
observed on any one day in a given month was averaged for 2008-13, 
providing a monthly average of the maximum daily number observed. The 
largest monthly average (71 animals) was recorded in November, as was 
the largest single daily count (122 animals). We conservatively assume 
that a maximum of 71 California sea lions could be in the vicinity of 
the action area and potentially subject to incidental harassment on 
each of the maximum eight days of pile driving activity.
    Steller Sea Lion--Steller sea lions were first documented at the 
NBKB waterfront in November 2008, while hauled out on submarines at 
Delta Pier, and have been periodically observed from October to April 
since that time, as determined by Navy waterfront surveys conducted 
from April 2008 through December 2013. Steller sea lions are 
occasionally observed in early May or late September, but have never 
been observed from approximately mid-May through mid-September. We 
assume, on the basis of waterfront observations (Agness and Tannenbaum, 
2009; Tannenbaum et al., 2009, 2011; HDR 2012a, 2012b; Hart Crowser, 
2013), that Steller sea lions use available haul-outs and foraging 
habitat similarly to California sea lions. On occasions when Steller 
sea lions are observed, they typically occur in mixed groups with 
California sea lions also present, allowing observers to confirm their 
identifications based on discrepancies in size and other physical 
characteristics.
    Abundance is calculated in the same manner described for California 
sea lions. That is, the maximum number of animals observed on any one 
day in a given month was averaged for 2008-13, providing a monthly 
average of the maximum daily number observed. The largest monthly 
average (six animals) was recorded in November, as was the largest 
single daily count (eleven animals). We conservatively assume that a 
maximum of six Steller sea lions could be in the vicinity of the action 
area and potentially subject to incidental harassment on each of the 
maximum eight days of pile driving activity.
    Harbor Seal--The harbor seal density used here is revised from that 
in the NMSDD (Hanser et al., 2014), on the basis of information 
regarding harbor seal haul-out behavior specific to Hood Canal (London 
et al., 2012). Jeffries et al. (2003) conducted aerial surveys of 
harbor seals in 1999 for the Washington Department of Fish and 
Wildlife, dividing the survey areas into seven strata (including five 
in inland waters and two in coastal waters). Survey effort in the Hood 
Canal stratum yielded a count of 711 harbor seals hauled out. In order 
to produce a total abundance estimate, a correction factor based on the 
proportion of time seals spend on land versus in the water over the 
course of a day must then be applied to account for animals in the 
water and not observed during survey counts. Previous density estimates 
used a correction factor of 1.53 (Huber et al., 2001) to derive a total 
Hood Canal population of 1,088 seals. That factor was based on data 
from tags (VHF transmitters) applied to harbor seals at six areas 
(Grays Harbor, Tillamook Bay, Umpqua River, Gertrude Island, 
Protection/Smith Islands, and Boundary Bay, BC) within two different 
harbor seal stocks (the coastal stock and the Washington inland waters 
stock) over four survey years. Although the sampling areas included 
both coastal and inland waters, with pooled correction factors of 1.50 
and 1.57, respectively, Huber et al. (2001) found no significant 
difference in the proportion of seals ashore among the six sites and no 
interannual variation at one site studied across years. The Hood Canal 
population is part of the inland waters stock, and while not 
specifically sampled, Jeffries et al. (2003) found the VHF data to be 
broadly applicable to the entire Washington harbor seal population. 
However, London et al. (2012) provide more recent data that is specific 
to Hood Canal. This more recent tagging data indicates that harbor 
seals in Hood Canal haul out only twenty percent of the time; 
therefore, the 1999 aerial surveys are considered to represent only 
twenty percent of the population, and the 1999 population estimate was 
updated to approximately 3,555 animals. This abundance, considered with 
the area of Hood Canal (358 km\2\), gives an abundance estimate of 9.9 
animals/km\2\.
    At any given time, some animals will be hauled out and some will be 
in the water and, to determine an instantaneous in-water density 
estimate, a secondary correction may be applied to account for harbor 
seals that are hauled out at any given moment. The London et al. (2012) 
data indicate that eighty percent of the population might be in the 
water at a given time; therefore a corrected density was derived from 
the number of harbor seals that are present in the water at any one 
time (eighty percent of 3,555, or approximately 2,844 individuals), 
divided by the area of the Hood Canal, yielding an estimate of 7.93 
animals/km\2\.
    We recognize that over the course of the day, while the proportion 
of animals in the water may not vary significantly, different 
individuals may enter and exit the water (i.e., it is probable that 
greater than eighty percent of seals will enter the water at some point 
during the day). Therefore, an instantaneous estimate of animals in the 
water at a given time may not produce an accurate assessment of the 
number of individuals that enter the water over the daily duration of 
the activity. However, no data exist regarding fine-scale harbor seal 
movements within the project area on time durations of less than a day, 
thus precluding an assessment of ingress or egress of different animals 
through the action area. As such, it is impossible, given available 
data, to determine exactly what number of individuals above eighty 
percent may potentially be exposed to underwater sound. Therefore, we 
are left to make a decision, on the basis of limited available 
information, regarding which of these two scenarios (i.e., one hundred 
percent versus eighty percent of harbor seals are in the water and 
exposed to sound) produces a more accurate estimate of the potential 
incidents of take.
    First, we understand that hauled-out harbor seals are necessarily 
at haul-outs. No significant harbor seal haul-outs are located within 
or near the action area. Harbor seals observed in the vicinity of the 
NBKB shoreline are rarely hauled-out (for example, in formal surveys 
during 2007-08, approximately 86 percent of observed seals were 
swimming), and when hauled-out, they do so opportunistically (i.e., on 
floating booms rather than established haul-outs). Harbor seals are 
typically unsuited for using manmade haul-outs at NBKB, which are used 
by the larger sea lions. Primary harbor seal haul-outs in Hood Canal 
are generally located at significant distance (20 km or more) from the 
action area in Dabob Bay or further south (see Figure 4-1 in the Navy's 
application), meaning that animals casually entering the water from 
haul-outs or flushing due to some disturbance at those locations would 
not be exposed to underwater sound from the project; rather, only those 
animals embarking on foraging trips and entering the action area may be 
exposed.
    Second, we know that harbor seals in Hood Canal are not likely to 
have a uniform distribution as is assumed through use of a density 
estimate, but are likely to be relatively concentrated near areas of 
interest such as the haul-outs found in Dabob Bay or foraging areas. 
The majority of the action area consists of the Level B harassment zone

[[Page 22497]]

in deeper waters of Hood Canal; past observations from surveys and 
required monitoring have confirmed that harbor seals are less abundant 
in these waters.
    Third, a typical pile driving day (in terms of the actual time 
spent driving) is somewhat shorter than may be assumed (i.e., 8-15 
hours) as a representative pile driving day based on daylight hours. 
Construction scheduling and notional production rates in concert with 
typical delays mean that hammers are active for only some fraction of 
time on pile driving ``days''. During recent years of construction at 
NBKB, pile driving occurred for an approximate average of seven hours 
per pile driving day.
    What we know tells us that (1) the turnover of harbor seals (in and 
out of the water) is occurring primarily outside the action area and 
would not be expected to result in a greater number of individuals 
entering the action area within a given day and being harassed than is 
assumed; (2) there are likely to be significantly fewer harbor seals in 
the majority of the action area than would be indicated by the 
uncorrected density; and (3) pile driving actually occurs over a 
limited timeframe on any given day (i.e., less total time per day than 
would be assumed based on daylight hours and non-continuously), 
reducing the amount of time over which new individuals might enter the 
action area within a given day. These factors lead us to believe that 
the corrected density is likely to more closely approximate the number 
of seals that may be found in the action area than does the uncorrected 
density, and there are no existing data that would indicate that the 
proportion of individuals entering the water within the predicted area 
of effect during pile driving would be dramatically larger than eighty 
percent. Therefore, using one hundred percent of the population to 
estimate density would likely result in an overestimate of potential 
take. Moreover, because the Navy is typically unable to determine from 
field observations whether the same or different individuals are being 
exposed, each observation is recorded as a new take, although an 
individual theoretically would only be considered as taken once in a 
given day.
    Finally, we note that during the course of previous IHAs issued for 
Navy activity at NBKB, the total estimate of actual incidents of take 
(observed takes and observations extrapolated to unobserved area) has 
been substantially less than the estimated numbers of take. This is 
almost certainly negatively biased, but the disparity does provide 
confirmation that we are not significantly underestimating takes.
    Killer Whales--Transient killer whales are uncommon visitors to 
Hood Canal, and may be present anytime during the year. Transient pods 
(six to eleven individuals per event) were observed in Hood Canal for 
lengthy periods of time (59-172 days) in 2003 (January-March) and 2005 
(February-June), feeding on harbor seals (London, 2006). These whales 
used the entire expanse of Hood Canal for feeding. The NMSDD used 
monthly unique sightings data collected over the period 2004-2010 and 
an average group size of 5.16 (Houghton et al., in prep.) to calculate 
densities on a seasonal basis for each of five geographic strata 
(Hanser et al., 2014).
    While transient killer whales are rare in the Hood Canal, it is 
possible that a pod of animals could be present. In the event that this 
occurred in a similar manner to prior occurrences (e.g., 59-172 days) 
and incidental take were not authorized appropriately, there could be 
significant project delays. In estimating potential incidences of take 
here, we make three assumptions: (1) Transient killer whales have a 
reasonable likelihood of occurrence in the project area; (2) if whales 
were present, they would occur in a pod of six animals (the minimum pod 
size seen in the 2003/2005 events but equivalent to the average pod 
size reported by Houghton et al. [in prep.]); and (3) the pod would be 
present and affected by project activities (i.e., within the larger 
vibratory Level B harassment zone) for two of the maximum eight days. 
We believe that it is unlikely the whales would remain in the area for 
a longer period in the presence of a harassing stimulus (i.e., pile 
driving). In the absence of any overriding contextual element (e.g., 
NBKB is not important as a breeding area, and provides no unusual 
concentration of prey), it is reasonable to assume that whales would 
leave the area if exposed to potentially harassing levels of sound on 
each day that they were present. In summary, we assume here that, if 
killer whales occurred in the project area, a pod of six whales would 
be present--and could potentially be harassed--for two days.
    Harbor Porpoise--During vessel-based line transect surveys on non-
construction days during the TPP, harbor porpoises were frequently 
sighted within several kilometers of the base, mostly to the north or 
south of the project area, but occasionally directly across from the 
NBKB waterfront on the far side of Toandos Peninsula. Harbor porpoise 
presence in the immediate vicinity of the base (i.e., within one 
kilometer) remained low. These data were used to generate a density for 
Hood Canal. Based on guidance from other line transect surveys 
conducted for harbor porpoises using similar monitoring parameters 
(e.g., boat speed, number of observers) (Barlow, 1988; Calambokidis et 
al., 1993; Carretta et al., 2001), the Navy determined the effective 
strip width for the surveys to be one kilometer, or a perpendicular 
distance of 500 m from the transect to the left or right of the vessel. 
The effective strip width was set at the distance at which the 
detection probability for harbor porpoises was equivalent to one, which 
assumes that all individuals on a transect are detected. Only sightings 
occurring within the effective strip width were used in the density 
calculation. By multiplying the trackline length of the surveys by the 
effective strip width, the total area surveyed during the surveys was 
471.2 km\2\. Thirty-eight individual harbor porpoises were sighted 
within this area, resulting in a density of 0.0806 animals/km\2\. To 
account for availability bias, or the animals which are unavailable to 
be detected because they are submerged, the Navy utilized a g(0) value 
of 0.54, derived from other similar line transect surveys (Barlow, 
1988; Calambokidis et al., 1993; Carretta et al., 2001). This resulted 
in a corrected density of 0.149 animals/km\2\.

     Table 5--Number of Potential Incidental Takes of Marine Mammals Within Various Acoustic Threshold Zones
----------------------------------------------------------------------------------------------------------------
                                                                            Underwater
                                                                 --------------------------------  Percentage of
                     Species                          Density                      Level B (120        stock
                                                                      Level A         dB) 1 2        abundance
----------------------------------------------------------------------------------------------------------------
California sea lion.............................          71 \3\               0             568             0.2
Steller sea lion................................           6 \3\               0              48             0.1
Harbor seal.....................................            7.93               0           2,056              57

[[Page 22498]]

 
Killer whale (transient)........................             n/a               0              12         4.9 \4\
Harbor porpoise.................................           0.149               0              40             0.4
----------------------------------------------------------------------------------------------------------------
\1\ The 160-dB acoustic harassment zone associated with impact pile driving would always be subsumed by the 120-
  dB harassment zone produced by vibratory driving. Therefore, takes are not calculated separately for the two
  zones.
\2\ For species with associated density, density was multiplied by largest ZOI (i.e., 32.4 km). The resulting
  value was rounded to the nearest whole number and multiplied by the days of activity. For species with
  abundance only, that value was multiplied directly by the days of activity. We assume for reasons described
  earlier that no takes would result from airborne noise.
\3\ Figures presented are abundance numbers, not density, and are calculated as the average of average daily
  maximum numbers per month, and presented for the month with the highest value. Abundance numbers are rounded
  to the nearest whole number for take estimation.
\4\ We assumed that a single pod of six killer whales could be present for as many as two days of the duration,
  and that harbor porpoise have the likely potential to be affected by project activities for as many as four
  days of the duration.

Analyses and Preliminary Determinations

Negligible Impact Analysis

    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.'' A negligible impact finding is based on the 
lack of likely adverse effects on annual rates of recruitment or 
survival (i.e., population-level effects). An estimate of the number of 
Level B harassment takes alone is not enough information on which to 
base an impact determination. In addition to considering estimates of 
the number of marine mammals that might be ``taken'' through behavioral 
harassment, we consider other factors, such as the likely nature of any 
responses (e.g., intensity, duration), the context of any responses 
(e.g., critical reproductive time or location, migration), as well as 
the number and nature of estimated Level A harassment takes, the number 
of estimated mortalities, and effects on habitat.
    Pile driving activities associated with the wharf maintenance 
project, as outlined previously, have the potential to disturb or 
displace marine mammals. Specifically, the specified activities may 
result in take, in the form of Level B harassment (behavioral 
disturbance) only, from underwater sounds generated from pile driving. 
Potential takes could occur if individuals of these species are present 
in the ensonified zone when pile driving is happening, which is likely 
to occur because (1) harbor seals, which are frequently observed along 
the NBKB waterfront, are present within the WRA; (2) sea lions, which 
are less frequently observed, transit the WRA en route to haul-outs to 
the south at Delta Pier; or (3) cetaceans or pinnipeds transit the 
larger Level B harassment zone outside of the WRA.
    No injury, serious injury, or mortality is anticipated given the 
methods of installation and measures designed to minimize the 
possibility of injury to marine mammals. The potential for these 
outcomes is minimized through the construction method and duration and 
the implementation of the planned mitigation measures. Specifically, 
vibratory hammers will be the primary method of installation, and this 
activity does not have significant potential to cause injury to marine 
mammals due to the relatively low source levels produced (less than 180 
dB rms) and the lack of potentially injurious source characteristics. 
Impact pile driving produces short, sharp pulses with higher peak 
levels and much sharper rise time to reach those peaks. The entire 
duration of the specified activity would be eight days; given the 
intensity of potential effects as described below, we do not expect 
that such a short duration could produce a greater than negligible 
impact on the affected stocks.
    When impact driving is necessary, required measures (use of a sound 
attenuation system, which reduces overall source levels as well as 
dampening the sharp, potentially injurious peaks, and implementation of 
shutdown zones) significantly reduce any possibility of injury. Given 
sufficient ``notice'' through use of soft start, marine mammals are 
expected to move away from a sound source that is annoying prior to its 
becoming potentially injurious. The likelihood that marine mammal 
detection ability by trained observers is high under the environmental 
conditions described for Hood Canal further enables the implementation 
of shutdowns to avoid injury, serious injury, or mortality.
    Effects on individuals that are taken by Level B harassment, on the 
basis of reports in the literature as well as monitoring from past 
projects at NBKB, will likely be limited to reactions such as increased 
swimming speeds, increased surfacing time, or decreased foraging (if 
such activity were occurring). Most likely, individuals will simply 
move away from the sound source and be temporarily displaced from the 
areas of pile driving, although even this reaction has been observed 
primarily only in association with impact pile driving. In response to 
vibratory driving, harbor seals (which may be somewhat habituated to 
human activity along the NBKB waterfront) have been observed to orient 
towards and sometimes move towards the sound. Repeated exposures of 
individuals to levels of sound that may cause Level B harassment are 
unlikely to result in hearing impairment or to significantly disrupt 
foraging behavior. Thus, even repeated Level B harassment of some small 
subset of the overall stock is unlikely to result in any significant 
realized decrease in fitness to those individuals, and thus would not 
result in any adverse impact to the stock as a whole. Level B 
harassment will be reduced to the level of least practicable impact 
through use of mitigation measures described herein and, if sound 
produced by project activities is sufficiently disturbing, animals are 
likely to simply avoid the project area while the activity is 
occurring.
    For pinnipeds, no rookeries are present in the project area, there 
are no haul-outs other than those provided opportunistically by man-
made objects, and the project area is not known to provide foraging 
habitat of any special importance (other than is afforded by the known 
migration of salmonids generally along the Hood Canal shoreline). No 
cetaceans are expected within the WRA. The pile driving activities 
analyzed here are similar to other nearby construction activities 
within the Hood Canal, including recent

[[Page 22499]]

projects conducted by the Navy at the same location as well as work 
conducted in 2005 for the Hood Canal Bridge (SR-104) by the Washington 
State Department of Transportation, which have taken place with no 
reported injuries or mortality to marine mammals, and no known long-
term adverse consequences from behavioral harassment.
    In summary, this negligible impact analysis is founded on the 
following factors: (1) The possibility of injury, serious injury, or 
mortality may reasonably be considered discountable; (2) the 
anticipated incidences of Level B harassment consist of, at worst, 
temporary (maximum of eight days) modifications in behavior; (3) the 
absence of any major rookeries and only a few isolated and 
opportunistic haul-out areas near or adjacent to the project site; (4) 
the absence of cetaceans within the WRA and generally sporadic 
occurrence outside the WRA; (5) the absence of any other known areas or 
features of special significance for foraging or reproduction within 
the project area; and (6) the presumed efficacy of the planned 
mitigation measures in reducing the effects of the specified activity 
to the level of least practicable impact. In addition, none of these 
stocks are listed under the ESA or designated as depleted under the 
MMPA. All of the stocks for which take is authorized are thought to be 
increasing or to be within OSP size. In combination, we believe that 
these factors, as well as the available body of evidence from other 
similar activities, including those conducted at the same time of year 
and in the same location, demonstrate that the potential effects of the 
specified activity will have only short-term effects on individuals. 
The specified activity is not expected to impact rates of recruitment 
or survival and will therefore not result in population-level impacts. 
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 monitoring and 
mitigation measures, we preliminarily find that the total marine mammal 
take from Navy's wharf maintenance activities will have a negligible 
impact on the affected marine mammal species or stocks.

Small Numbers Analysis

    The numbers of animals authorized to be taken for all stocks (other 
than harbor seals) would be considered small relative to the relevant 
stocks or populations (ranging from 0.1 to 4.9 percent) even if each 
estimated taking occurred to a new individual--an extremely unlikely 
scenario. For pinnipeds occurring at the NBKB waterfront, there will 
almost certainly be some overlap in individuals present day-to-day. 
Further, for the pinniped species, these takes could potentially occur 
only within some small portion of the overall regional stock. For 
example, of the estimated 296,750 California sea lions, only certain 
adult and subadult males--believed to number approximately 3,000-5,000 
by Jeffries et al. (2000)--travel north during the non-breeding season. 
That number has almost certainly increased with the population of 
California sea lions--the 2000 SAR for California sea lions reported an 
estimated population size of 204,000-214,000 animals--but likely 
remains a relatively small portion of the overall population.
    For harbor seals, takes are likely to occur only within some 
portion of the population, rather than to animals from the Hood Canal 
stock as a whole. As described previously (see ``Description of Marine 
Mammals in the Area of the Specified Activity''), established harbor 
seal haul-outs are located at such a distance from the project site 
that we would not expect the majority of individual animals comprising 
the total stock to occur within the affected area, especially over such 
a short duration (eight days maximum). Therefore, we expect that the 
proposed authorized take level represents repeated exposures of a much 
smaller number of individuals in relation to the total stock size. 
Further, animals that are resident to Hood Canal, to which any 
incidental take would accrue, represent only seven percent of the best 
estimate of the larger Washington inland waters harbor seal abundance.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the mitigation and monitoring 
measures, we preliminarily find that small numbers of marine mammals 
will be taken relative to the populations of the affected species or 
stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    There are no relevant subsistence uses of marine mammals implicated 
by this action. Therefore, we have determined that the total taking of 
affected species or stocks would not have an unmitigable adverse impact 
on the availability of such species or stocks for taking for 
subsistence purposes.

Endangered Species Act (ESA)

    No marine mammal species listed under the ESA are expected to be 
affected by these activities. Therefore, we have determined that a 
section 7 consultation under the ESA is not required.

National Environmental Policy Act (NEPA)

    The Navy prepared an Environmental Assessment (EA) to consider the 
direct, indirect and cumulative effects to the human environment 
resulting from the wharf maintenance project. NMFS has reviewed the EA 
and believes it appropriate to adopt the EA in order to assess the 
impacts to the human environment of issuance of an IHA to the Navy and 
subsequently sign our own Finding of No Significant Impact (FONSI). 
Information in the Navy's application, the Navy's EA, and this notice 
collectively provide the environmental information related to proposed 
issuance of this IHA for public review and comment. The EA is available 
for review at www.nmfs.noaa.gov/pr/permits/incidental/construction.htm. 
We will review all comments submitted in response to this notice as we 
complete the NEPA process, including a final decision of whether to 
adopt the Navy's EA and sign a FONSI, prior to a final decision on the 
incidental take authorization request.

Proposed Authorization

    As a result of these preliminary determinations, we propose to 
issue an IHA to the Navy for conducting the described wharf maintenance 
activities in the Hood Canal, from July 16, 2015 through January 15, 
2016, provided the previously mentioned mitigation, monitoring, and 
reporting requirements are incorporated. The proposed IHA language is 
provided next.
    This section contains a draft of the IHA itself. The wording 
contained in this section is proposed for inclusion in the IHA (if 
issued).
    1. This Incidental Harassment Authorization (IHA) is valid from 
July 16, 2015 through January 15, 2016.
    2. This IHA is valid only for pile driving and removal activities 
associated with maintenance of Explosive Handling Wharf #1 (EHW-1) in 
the Hood Canal, Washington.
    3. General Conditions
    (a) A copy of this IHA must be in the possession of the Navy, its 
designees, and work crew personnel operating under the authority of 
this IHA.
    (b) The species authorized for taking are the harbor seal (Phoca 
vitulina),

[[Page 22500]]

California sea lion (Zalophus californianus), killer whale (transient 
only; Orcinus orca), Steller sea lion (Eumetopias jubatus), and the 
harbor porpoise (Phocoena phocoena).
    (c) The taking, by Level B harassment only, is limited to the 
species listed in condition 3(b). See Table 1 (attached) for numbers of 
take authorized.
    (d) The taking by injury (Level A harassment), serious injury, or 
death of any of the species listed in condition 3(b) of the 
Authorization or any taking of any other species of marine mammal is 
prohibited and may result in the modification, suspension, or 
revocation of this IHA.
    (e) The Navy shall conduct briefings between construction 
supervisors and crews, marine mammal monitoring team, and Navy staff 
prior to the start of all pile driving activity, and when new personnel 
join the work, in order to explain responsibilities, communication 
procedures, marine mammal monitoring protocol, and operational 
procedures.
    4. Mitigation Measures
    In order to ensure the least practicable impact on the species 
listed in condition 3(b), the holder of this Authorization is required 
to implement the following mitigation measures:
    (a) During impact pile driving, the Navy shall implement a minimum 
shutdown zone of 10 m radius around the pile, to be effective for all 
species of pinniped, and a minimum shutdown zone of 29 m radius around 
the pile, to be effective for all species of cetacean. If a marine 
mammal comes within the relevant zone, such operations shall cease.
    (b) During vibratory pile driving and removal, the Navy shall 
implement a minimum shutdown zone of 10 m radius around the pile for 
marine mammals. If a marine mammal comes within this zone, such 
operations shall cease.
    (c) The Navy shall establish monitoring locations as described in 
the Marine Mammal Monitoring Plan (Monitoring Plan; attached). For all 
pile driving and removal activities, a minimum of three observers shall 
be on duty, in addition to a monitoring coordinator. Two of the 
observers' primary responsibility shall be to monitor the shutdown 
zones, while the additional observer shall be positioned for optimal 
monitoring of the surrounding waters within the Waterfront Restricted 
Area (WRA). These observers shall record all observations of marine 
mammals, regardless of distance from the pile being driven, as well as 
behavior and potential behavioral reactions of the animals.
    (d) Monitoring shall take place from fifteen minutes prior to 
initiation of pile driving activity through thirty minutes post-
completion of pile driving activity. Pre-activity monitoring shall be 
conducted for fifteen minutes to ensure that the shutdown zone is clear 
of marine mammals, and pile driving may commence when observers have 
declared the shutdown zone clear of marine mammals. In the event of a 
delay or shutdown of activity resulting from marine mammals in the 
shutdown zone, animals shall be allowed to remain in the shutdown zone 
(i.e., must leave of their own volition) and their behavior shall be 
monitored and documented. Monitoring shall occur throughout the time 
required to drive a pile. The shutdown zone must be determined to be 
clear during periods of good visibility (i.e., the entire shutdown zone 
and surrounding waters within the WRA must be visible to the naked 
eye).
    (e) If a marine mammal approaches or enters the shutdown zone, all 
pile driving activities at that location shall be halted (i.e., 
implementation of shutdown at one pile driving location may not 
necessarily trigger shutdown at other locations when pile driving is 
occurring concurrently). If pile driving is halted or delayed at a 
specific location due to the presence of a marine mammal, the activity 
may not commence or resume until either the animal has voluntarily left 
and been visually confirmed beyond the shutdown zone or fifteen minutes 
have passed without re-detection of the animal.
    (f) Monitoring shall be conducted by qualified observers, as 
described in the Monitoring Plan. Trained observers shall be placed 
from the best vantage point(s) practicable (i.e., provides the most 
unobstructed view of the monitoring zones and are at the highest 
elevation possible) to monitor for marine mammals and implement 
shutdown or delay procedures when applicable through communication with 
the equipment operator.
    (g) Approved sound attenuation devices shall be used during impact 
pile driving operations. The Navy shall implement the necessary 
contractual requirements to ensure that such devices are capable of 
achieving optimal performance, and that deployment of the device is 
implemented properly such that no reduction in performance may be 
attributable to faulty deployment.
    (h) The Navy shall use soft start techniques recommended by NMFS 
for vibratory and impact pile driving. Soft start for vibratory drivers 
requires contractors to initiate sound for fifteen seconds at reduced 
energy followed by a thirty-second waiting period. This procedure is 
repeated two additional times. Soft start for impact drivers requires 
contractors to provide an initial set of strikes at reduced energy, 
followed by a thirty-second waiting period, then two subsequent reduced 
energy strike sets. Soft start shall be implemented at the start of 
each day's pile driving and at any time following cessation of pile 
driving for a period of thirty minutes or longer. Soft start for impact 
drivers must be implemented at any time following cessation of impact 
driving for a period of thirty minutes or longer. The Navy may 
discontinue use of vibratory soft starts if unsafe working conditions 
believed to result from implementation of the measure are reported by 
the contractor, verified by an independent safety inspection, and 
reported to NMFS.
    (i) Pile driving shall only be conducted during daylight hours and 
when the entire shutdown zone is visible.
    5. Monitoring
    The holder of this Authorization is required to conduct marine 
mammal monitoring during pile driving activity. Marine mammal 
monitoring and reporting shall be conducted in accordance with the 
Monitoring Plan.
    (a) The Navy shall collect sighting data and behavioral responses 
to pile driving for marine mammal species observed in the region of 
activity during the period of activity. All observers shall be trained 
in marine mammal identification and behaviors, and shall have no other 
construction related tasks while conducting monitoring.
    (b) For all marine mammal monitoring, the information shall be 
recorded as described in the Monitoring Plan.
    6. Reporting
    The holder of this Authorization is required to:
    (a) Submit a draft report on all marine mammal monitoring conducted 
under the IHA within ninety calendar days of the end of the in-water 
work period. A final report shall be prepared and submitted within 
thirty days following resolution of comments on the draft report from 
NMFS. This report must contain the informational elements described in 
the Monitoring Plan, at minimum (see attached).
    (b) 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 this IHA 
(as determined by the lead observer), such as an injury (Level A 
harassment), serious injury, or

[[Page 22501]]

mortality, Navy shall immediately cease the specified activities and 
report the incident to the Office of Protected Resources (301-427-
8425), NMFS, and the West Coast Regional Stranding Coordinator (206-
526-6550), NMFS. 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).
    Activities shall not resume until NMFS is able to review the 
circumstances of the prohibited take. NMFS will work with Navy to 
determine what measures are necessary to minimize the likelihood of 
further prohibited take and ensure MMPA compliance. Navy may not resume 
their activities until notified by NMFS.
    i. In the event that Navy discovers an injured or dead marine 
mammal, and the lead 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), Navy shall immediately report 
the incident to the Office of Protected Resources, NMFS, and the West 
Coast Regional Stranding Coordinator, NMFS.
    The report must include the same information identified in 6(b)(i) 
of this IHA. Activities may continue while NMFS reviews the 
circumstances of the incident and makes a final determination on the 
cause of the reported injury or death. NMFS will work with Navy to 
determine whether additional mitigation measures or modifications to 
the activities are appropriate.
    ii. In the event that Navy discovers an injured or dead marine 
mammal, and the lead observer determines that the injury or death is 
not associated with or related to the activities authorized in the IHA 
(e.g., previously wounded animal, carcass with moderate to advanced 
decomposition, scavenger damage), Navy shall report the incident to the 
Office of Protected Resources, NMFS, and the West Coast Regional 
Stranding Coordinator, NMFS, within 24 hours of the discovery. Navy 
shall provide photographs or video footage or other documentation of 
the stranded animal sighting to NMFS. The cause of injury or death may 
be subject to review and a final determination by NMFS.
    7. This Authorization may be modified, suspended or withdrawn if 
the holder fails to abide by the conditions prescribed herein, or if 
the authorized taking is having more than a negligible impact on the 
species or stock of affected marine mammals.

Request for Public Comments

    We request comment on our analysis, the draft authorization, and 
any other aspect of this Notice of Proposed IHA for Navy's wharf 
maintenance activities. Please include with your comments any 
supporting data or literature citations to help inform our final 
decision on Navy's request for an MMPA authorization.

    Dated: April 16, 2015.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2015-09253 Filed 4-21-15; 8:45 am]
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