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

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2014-12906

## Record

- **Collection:** Federal Register
- **Document type:** Notice
- **Published:** June 6, 2014
- **Citation:** 79 FR 32828

## Text

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XD282
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Wharf Construction Project

AGENCY:

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

ACTION:

Notice; proposed incidental harassment authorization; request for comments.

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 construction 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 July 7, 2014.

ADDRESSES:

Comments on the application should be addressed to Jolie Harrison, Supervisor, Incidental Take Program, 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:
NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. 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 to the Internet at
www.nmfs.noaa.gov/pr/permits/incidental.htm
without change. All personal identifying information (e.g., name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information.

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.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 Impact Statement (EIS) for this project. We acted as a cooperating agency on development of that analysis and subsequently adopted the EIS and issued our own Record of Decision (ROD; 2012), prior to issuing the first IHA for this project, in accordance with NEPA and the regulations published by the Council on Environmental Quality. We reaffirmed the existing 2012 ROD before issuing an IHA in 2013 for the second year of project construction. Information in the Navy's application, the Navy's EIS (2012), 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, with the exception of the Navy's EIS, which is publicly available at
www.nbkeis.com
(accessed May 2, 2014). We will review all comments submitted in response to this notice as we complete the NEPA process, including a decision of whether to reaffirm the existing ROD, 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, either in specific regulations or in an authorization.

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 prescriptions through either specific regulations or an authorization 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 has the potential to injure a marine mammal or marine mammal stock in the wild; or 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. The former is termed Level A harassment and the latter is termed Level B harassment.

Summary of Request

On January 10, 2014, we received a request from the Navy for authorization to take marine mammals incidental to pile driving associated with the construction of an explosives handling wharf (EHW-2) in the Hood Canal at Naval Base Kitsap in Bangor, WA (NBKB). The Navy submitted a revised version of the request on April 11, 2014, which we deemed adequate and complete. The Navy proposes to continue this multi-year project, involving impact and vibratory pile driving conducted within the approved

in-water work window. This IHA would cover only the third year (in-water work window) of the project, from July 16, 2014, through February 15, 2015.

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, if issued. The Navy received IHAs, effective from July 16-February 15, in 2012-13 (77 FR 42279) and 2013-14 (78 FR 43148). Additional IHAs were issued to the Navy in recent years for marine construction projects on the NBKB waterfront. These 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 EHW-2 (76 FR 38361); a two-year maintenance project on the existing explosives handling wharf (EHW-1) conducted in 2011-12 and 2012-13 (76 FR 30130 and 77 FR 43049); 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.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 continue construction of the EHW-2 facility at NBKB in order to support future program requirements for submarines berthed at NBKB. The Navy has determined that construction of EHW-2 is necessary because the existing EHW alone will not be able to support future program requirements. All piles would be driven with a vibratory hammer for their initial embedment depths, while select piles may be finished with an impact hammer for proofing, as necessary. A maximum of three vibratory drivers and one impact driver may be used simultaneously. Proofing involves striking a driven pile with an impact hammer to verify that it provides the required load-bearing capacity, as indicated by the number of hammer blows per foot of pile advancement. Sound attenuation measures (i.e., bubble curtain) would be used during all impact hammer operations.

Dates and Duration

The allowable season for in-water work, including pile driving, at NBKB is July 16 through February 15, a window 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. Under the proposed action—which includes only the portion of the project that would be completed under this proposed IHA—a maximum of 195 pile driving days would occur. Pile driving may occur on any day during the in-water work window.

Impact pile driving during the first half of the in-water work window (July 16 to September 15) may only occur between two hours after sunrise and two hours before sunset to protect breeding marbled murrelets (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 16 and February 15, may occur during daylight hours (sunrise to sunset). Other construction (not in-water) may occur between 7:00 a.m. and 10:00 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 2-4 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

Development of necessary facilities for handling of explosive materials is part of the Navy's sea-based strategic deterrence mission. The EHW-2 consists of two components: (1) The wharf proper (or Operations Area), including the warping wharf; and (2) two access trestles. Please see Figures 1-1 and 1-2 of the Navy's application for conceptual and schematic representations of the EHW-2.

The wharf proper will lie approximately 183 m offshore at water depths of 18-30 m, and will consist of the main wharf, a warping wharf, and lightning protection towers, all pile-supported. It will include a slip (docking area) for submarines, surrounded on three sides by operational wharf area. The access trestles will connect the wharf to the shore. There will be an entrance trestle and an exit trestle; these will be combined over shallow water to reduce overwater area. The trestles will be pile-supported on 24-in steel pipe piles driven approximately 9 m into the seafloor. Spacing between bents (rows of piles) will be 8 m. Concrete pile caps will be cast in place and will support pre-cast concrete deck sections.

For the entire project, a total of up to 1,250 permanent piles ranging in size between 24-48 inches in diameter will be driven in-water to construct the wharf. Construction also requires temporary installation of up to 150 falsework piles used as an aid to guide permanent piles to their proper locations. Falsework piles, which are removed upon installation of the permanent piles, are usually steel pipe piles and are driven and removed using a vibratory driver. It has not been determined exactly what parts or how much of the project will be constructed in any given year; however, a maximum of 195 days of pile driving may occur per in-water work window. The analysis contained herein is based upon the maximum of 195 pile driving days, rather than any specific number of piles driven. Table 1 summarizes the number and nature of piles required for the entire project, rather than what subset of piles may be expected to be driven

during the third year of construction proposed for this IHA.

Table 1—Summary of Piles Required for Wharf Construction
[in total]

Feature
Quantity

Total number of permanent in-water piles
Up to 1,250.

Size and number of main wharf piles

24-in: 140.
36-in: 157.
48-in: 263.

Size and number of warping wharf piles

24-in: 80.
36-in: 190.

Size and number of lightning tower piles

24-in: 40.
36-in: 90.

Size and number of trestle piles

24-in: 57.
36-in: 233.

Falsework piles
Up to 150, 18- to 24-in.

Maximum pile driving duration
195 days (under one-year IHA).

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. 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, increased usage of an impact hammer will occur.

Unless difficult driving conditions are encountered, an impact hammer will only be used to proof the load-bearing capacity of approximately every fourth or fifth pile. The industry standard is to proof every pile with an impact hammer; however, in an effort to reduce blow counts from the impact hammer, the engineer of record has agreed to only proof every fourth or fifth pile. A maximum of 200 strikes would be required to proof each pile. Pile production rates are dependent upon required embedment depths, the potential for encountering difficult driving conditions, and the ability to drive multiple piles without a need to relocate the driving rig. Under best-case scenarios (i.e., shallow piles, driving in optimal conditions, using multiple driving rigs), it may be possible to install enough pilings with the vibratory hammer that proofing may be required for up to five piles in a day. Under this scenario, with a single impact hammer used to proof up to five piles per day at 200 strikes per pile, it is estimated that up to a maximum of 1,000 strikes from an impact hammer would be required per day.

If difficult subsurface driving conditions (e.g., cobble/boulder zones) are encountered that cause refusal with the vibratory equipment, it may be necessary to use an impact hammer to drive some piles for the remaining portion of their required depth. The worst-case scenario is that a pile would be driven for its entire length using an impact hammer. Given the uncertainty regarding the types and quantities of boulders or cobbles that may be encountered, and the depth at which they may be encountered, the number of strikes necessary to drive a pile its entire length could be approximately 1,000 to 2,000 strikes per pile. The Navy estimates that a possible worst-case daily scenario would require driving three piles full length (at a worst-case of 2,000 strikes per pile) after the piles have become hung on large boulders early in the installation process, with proofing of an additional two piles (at 200 strikes each) that were able to be installed primarily via vibratory means. This worst-case scenario would therefore result in a maximum of 6,400 strikes per day. All piles driven or struck with an impact hammer would be surrounded by a bubble curtain over the full water column to minimize in-water sound. Up to three vibratory rigs and one impact rig may be used at a time. Pile production rate (number of piles driven per day) is affected by many factors: Size, type (vertical versus angled), and location of piles; weather; number of driver rigs operating; equipment reliability; geotechnical (subsurface) conditions; and work stoppages for security or environmental reasons (such as presence of marine mammals).

Description of Work Accomplished
—During the first in-water work season, the contractor completed installation of 184 piles to support the main segment of the access trestle. Driven piles ranged in size from 24- to 36-in at depths ranging from 0 to 15 m. A maximum of two vibratory pile drivers and one impact hammer were operated concurrently.

During the second season, installation of 411 total piles was completed, including all 315 of the wharf deck plumb piles (non-fender) and 24 of the 34 total wharf deck Lead Rubber Bearing (LRB) dolphins (clusters of four piles per dolphin). Installed piles ranged in size from 36- to 48-in at depths ranging from 12-29 m. As before, a maximum two vibratory pile drivers and one impact hammer were operated concurrently.

During the third season, the Navy expects to complete installation of the wharf deck LRBs, piling support for the warping wharf, lightning towers, and trestle deck closure as well as all fender piles. The Navy expects to complete the project in January 2016. The amount of progress made under this proposed IHA, if issued, would determine necessity of a fourth IHA for the 2015-16 in-water work window.

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 May 2, 2014).

Table 2 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 Pacific SARs (e.g., Carretta
et al.,
2013a), while the Steller sea lion and transient killer whale are treated in the Alaska SARs (e.g., Allen and Angliss, 2013a).

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 2—Marine Mammals Potentially Present in the Vicinity of NBKB

Species
Stock

ESA/MMPA
status;
strategic

(Y/N)
1

Stock abundance (CV, N
min
, most
recent
abundance

survey)
2

PBR
3

Annual M/SI
4

Relative occurrence in Hood Canal;
season of occurrence

Order Cetartiodactyla—Cetacea—Superfamily Odontoceti (toothed whales, dolphins, and porpoises)

Family Delphinidae

Killer whale

West coast transient.
5

6

—;N
243 (n/a; 2006)
2.4
0
Rare; year-round (but last observed in 2005).

Family Phocoenidae (porpoises)

Harbor porpoise

Washington inland waters.
7

—;N
10,682 (0.38; 7,841; 2003)
63
≥2.2
Possible regular presence; year-round.

Order Carnivora—Superfamily Pinnipedia

Family Otariidae (eared seals and sea lions)

California sea lion
U.S.
—; N
296,750 (n/a; 153,337; 2008)
9,200
≥431
Seasonal/common; Fall to late spring (Aug to Jun).

Steller sea lion

Eastern U.S.
5

—; N
8

63,160-78,198 (n/a; 57,966; 2008-11)
9

10
1,552

65.1
Seasonal/occasional; Fall to late spring (Sep to May).

Family Phocidae (earless seals)

Harbor seal

Washington inland waters.
7

—; N
14,612 (0.15; 12,844; 1999)
771
13.4
Common; Year-round 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; N
min
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 specie's (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 2013 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 2013 SARs. This information was made available for public comment and is currently under review and therefore may be revised prior to finalizing the 2013 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 and PBR values, as these represent the best available information for use in this document.

8
The eastern distinct population segment of the Steller sea lion, previously listed under the ESA as threatened, was delisted on December 4, 2013 (78 FR 66140; November 4, 2013). Because this stock is not below its OSP size and the level of direct human-caused mortality does not exceed PBR, this delisting action implies that the stock is no longer designated as depleted or as a strategic stock under the MMPA.

9
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).

10
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 2,069.

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 May 5, 2014), and no records are found in the literature. In January-February 2012, one individual was observed in Hood Canal repeatedly over a period of several weeks. No sightings have been recorded since that time.

Gray whales generally migrate southbound past Washington in late December and January, and transit past 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°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, 2013a).

Data from 2005-10 show a total mean annual mortality rate of 5.71 (CV = 0.23) sea lions per year from observed fisheries and 11.25 reported takes per year that could not be assigned to specific fisheries, for an approximate total from all fisheries of 17 eastern Steller sea lions (Allen and Angliss, 2013a). In addition, opportunistic observations and stranding data indicate that an additional 32 animals are killed or seriously injured each year through interaction with commercial and recreational troll fisheries and by entanglement (Allen and Angliss, 2013b). The annual average take for subsistence harvest in Alaska was 11.9 individuals in 2004-08 (Allen and Angliss, 2013a). Data on community subsistence harvests is no longer being collected, and this average is retained as an estimate for current and future subsistence harvest. Sea lion deaths are also known to occur because of illegal shooting, vessel strikes, or capture in research gear and other traps, totaling 4.2 animals per year from 2007-11 (Allen and Angliss, 2013b). The total annual human-caused mortality is a minimum estimate because takes via fisheries interactions and subsistence harvest in Canada are poorly known, although are believed to be small.

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, 2013a) 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, 2013b), 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 are 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.,
2013a). 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). Only the Washington inland waters stock may be found in the project area.

Recent genetic evidence suggests that harbor seals of Washington inland waters may 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.
(2013b) suggest division of the Washington inland waters stock into three new populations, and present these as prospective 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 Juan Islands, and the Strait of Juan de Fuca); and (3) Hood Canal. Until this stock structure is accepted, we consider a single Washington inland waters stock.

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 (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, provides the abundance estimate (see Table 2).

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 the Washington inland waters stock is considered to be within its OSP size (Jeffries
et al.,
2003).

Data from 2007-11 indicate that a minimum of four harbor seals are killed annually in Washington inland waters commercial fisheries, while mean annual mortality for recreational fisheries is one seal (Carretta
et al.,
2013b). Animals captured east of Cape Flattery are assumed to belong to this stock. The estimate is considered a minimum because there are likely additional animals killed in unobserved fisheries and because not all animals stranding as a result of fisheries interactions are likely to be recorded. Another 8.4 harbor seals per year are estimated to be killed as a result of various non-fisheries human interactions (Carretta
et al.,
2013b). Tribal subsistence takes of this stock may occur, but no data on recent takes are available.

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).

There are no known pupping or regular haul-out sites in the project area, 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). During most of the year, all age and sex classes (except neonates) occur in the project area throughout the period of construction activity. Because there are no known regular pupping sites in the vicinity of the project area, harbor seal neonates would not generally be expected to be present during pile driving. However, 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.

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.,
2013a). 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 Nino years when pup production declined dramatically before quickly rebounding (Carretta
et al.,
2013a). The maximum population growth rate was 9.2 percent when pup counts from the El Niño 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.,
2013a).

Data from 2003-09 indicate that a minimum of 337 (CV = 0.56) California sea lions are killed annually in commercial fisheries. In addition, a summary of stranding database records for 2005-09 shows an annual average of 65 such events, which is likely a gross underestimate because most carcasses are not recovered. California sea lions may also be removed because of predation on endangered salmonids (seventeen per year, 2008-10) or incidentally captured during scientific research (three per year, 2005-09) (Carretta
et al.,
2013a). Sea lion mortality has also 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 May 8, 2014).

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). 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).

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
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 (2013a) 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.

Although certain commercial fisheries are known to have potential for interaction with killer whales and other mortality, resulting from shooting, ship strike, or entanglement, has been of concern in the past, the estimated level of human caused mortality and serious injury is currently considered to be zero for this stock (Allen and Angliss, 2013a). However, this could represent an underestimate as regards total fisheries-related mortality due to a lack of data concerning marine mammal interactions in Canadian commercial fisheries known to have potential for interaction with killer whales. Any such interactions are thought to be few in number (Allen and Angliss, 2013a). No ship strikes have been reported for this stock, and shooting of transients is

thought to be minimal because their diet is based on marine mammals rather than fish. There are no reports of a subsistence harvest of killer whales in Alaska or Canada.

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.,
2013a). 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.,
2013a).

Data from 2005-09 indicate that a minimum of 2.2 Washington inland waters harbor porpoises are killed annually in U.S. commercial fisheries (Carretta
et al.,
2013a). Animals captured in waters east of Cape Flattery are assumed to belong to this stock. This estimate is considered a minimum because the Washington Puget Sound Region salmon set/drift gillnet fishery has not been observed since 1994, and because of a lack of knowledge about the extent to which harbor porpoise from U.S. waters frequent the waters of British Columbia and are, therefore, subject to fishery-related mortality. However, harbor porpoise takes in the salmon drift gillnet fishery are unlikely to have increased since the fishery was last observed, when few interactions were recorded, due to reductions in the number of participating vessels and available fishing time. Fishing effort and catch have declined throughout all salmon fisheries in the region due to management efforts to recover ESA-listed salmonids (Carretta
et al.,
2013a). In addition, an estimated 0.4 animals per year are killed by non-fishery human causes (e.g., ship strike, entanglement). 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.,
2013a).

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 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 (μPa). 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 μPa). 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 μPa and all airborne sound levels in this document are referenced to a pressure of 20 μPa.

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 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 3. Details of the source types are described in the following text.

Table 3—Representative Sound Levels of Anthropogenic Sources

Sound source
Frequency 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 pile
10-1,500
180 dB rms at 10 m
Reyff, 2007.

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-shell (CISS) pile
10-1,500
195 dB rms at 10 m
Reviewed in Hastings and Popper, 2005.

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 (Hemilä
et al.,
2006; Kastelein
et al.,
2009; Reichmuth
et al.,
2013).

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 2. 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 μPa
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 μPa 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-weighted SEL (for the sequence of received pulses) of approximately 198 dB re 1 μPa
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 μPa
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 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 construction 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 construction 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 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 were coupled with practical spreading loss to estimate zones of influence (ZOI; see “Estimated Take by Incidental Harassment”). These values were then refined based on in situ measurements performed during the TPP, for similar pile driving activity and within the EHW-2 project footprint, to develop mitigation measures for EHW-2 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

construction project. In addition to the measures described later in this section, the Navy would employ the following standard mitigation measures:

(a) Conduct briefings between construction supervisors and crews, marine mammal monitoring team, and Navy staff prior to the start of all pile driving activity, and when new personnel join the work, in order to explain responsibilities, communication procedures, marine mammal monitoring protocol, and operational procedures.

(b) For in-water heavy machinery work other than pile driving (using, e.g., standard barges, tug boats, barge-mounted excavators, or clamshell equipment used to place or remove material), if a marine mammal comes within 10 m, operations shall cease and vessels shall reduce speed to the minimum level required to maintain steerage and safe working conditions. This type of work could include the following activities: (1) Movement of the barge to the pile location; (2) positioning of the pile on the substrate via a crane (i.e., stabbing the pile); (3) removal of the pile from the water column/substrate via a crane (i.e., deadpull); or (4) the placement of sound attenuation devices around the piles. For these activities, monitoring would take place from 15 minutes prior to initiation until the action is complete.

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 8. However, during impact pile driving, the Navy would implement a minimum shutdown zone of 85 m radius for cetaceans and 20 m radius for pinnipeds around all pile driving activity. The modeled injury threshold distances are approximately 22 m and 5 m, respectively, but the distances are increased based on in-situ recorded sound pressure levels during the TPP. During vibratory driving, the shutdown zone would be 10 m distance from the source for all animals. These precautionary measures are intended to further reduce any possibility of acoustic injury, as well as to account for any undue reduction in the modeled zones stemming from the assumption of 10 dB attenuation from use of a bubble curtain (see discussion later in this section).

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 8. 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.htm
), 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;

• 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 Table 6-5 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. See Tables 6-6 and 6-7 of the Navy's application.

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 the best estimate of average SPL (rms) reduction, assuming appropriate deployment and no problems with the equipment. In looking at other monitored projects prior to completion of the TPP, the Navy determined with our concurrence that an assumption of 10 dB realized attenuation was realistic. Therefore, a 10 dB reduction was used in the Navy's analysis of pile driving noise in the initial environmental analyses for the EHW-2 project. The Navy's analysis is retained here. While acknowledging that empirical evidence from the TPP indicates that the 10 dB target has not been consistently achieved, we did not require the Navy to revisit their acoustic modeling because (1) shutdown and disturbance zones for the second and third construction years are based on in situ measurements rather than the original modeling that assumed 10 dB attenuation from a bubble curtain and (2) take estimates are not affected because they are based on a combined modeled sound field (i.e., concurrent operation of impact and vibratory drivers) rather than there being separate take estimates for impact and vibratory pile driving.

Bubble curtains shall be used during all impact pile driving. The device will distribute air bubbles around 100 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.

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-February 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.

It is the Navy's contention that this situation is unique to the EHW-2 project, in comparison with other common marine construction projects requiring pile driving. The design specifications of the wharf, which require relatively large-diameter piles to be driven to embedment in relatively deep water through stiff glacial soil, mean that relatively greater driving energy, and therefore a larger hammer, is required for successful embedment. The Marine Mammal Commission previously recommended that we require the Navy to consult with the Washington State Department of Transportation and/or the California Department of Transportation to determine whether soft start procedures can be used safely with the vibratory hammers that the Navy plans to use. We agreed with that recommendation and are still working to facilitate such a consultation in order to determine whether the potentially significant human safety issue is inherent to implementation of the measure or is due to operator error. However, our interest in examining this issue is related to our need to understand the conditions under which vibratory soft start may be advisable from an engineering perspective for future projects.

For this proposed IHA and for the remainder of the EHW-2 project, as a result of this potential risk to human safety, we have determined vibratory soft start to not currently be practicable. Therefore, the measure will not be required. We have further determined this measure unnecessary to providing the means of effecting the least practicable impact on marine mammals and their habitat.

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.

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 the IHA application for year two of this project. It will be applied to year three of this project and can be found on the Internet at
www.nmfs.noaa.gov/pr/permits/incidental.htm.
The plan has been successfully implemented by the Navy under the previous IHA and 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:

• MMOs would be located at the best vantage point(s) in order to properly see the entire shutdown zone and as much of the disturbance zone as possible.

• During all observation periods, observers will use binoculars and the naked eye to search continuously for marine mammals.

• If the shutdown zones are obscured by fog or poor lighting conditions, pile driving at that location will not be initiated until that zone is visible. Should such conditions arise while impact driving is underway, the activity would be halted.

• The shutdown and disturbance zones around the pile will be monitored for the presence of marine mammals before, during, and after any pile driving or removal activity.

Individuals implementing the monitoring protocol will assess its effectiveness using an adaptive approach. Monitoring biologists will use their best professional judgment throughout implementation and seek improvements to these methods when deemed appropriate. Any modifications to protocol will be coordinated between NMFS and the Navy.

Data Collection

We require that observers use approved data forms. Among other pieces of information, the Navy will record detailed information about any implementation of shutdowns, including the distance of animals to the pile and description of specific actions that ensued and resulting behavior of the animal, if any. 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

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2014-12906. Public record. Not legal advice.