Federal Register / Vol. 85, No. 239 / Friday, December 11, 2020 / Notices 80027 

States Coast Pilot®. This transition has 

resulted in a broad market providing 

product differentiation with optional 

value-added features. However, Coast 

Survey is in the process of reducing the 

amount of traditional NOAA paper 

nautical products that it maintains as it 

moves to facilitating a method from 

which paper charts can be derived from 

the NOAA’s electronic navigational 

charts (NOAA ENC®) found on website: 

https://nauticalcharts.noaa.gov/charts/ 

noaa-enc.html. Within the next five 

years, the number of unique charts that 

will be available for vendors to print 

will be reduced by roughly 60%. Coast 

Survey recognized that a hold on 

accepting new applications must be put 

in place until the final number of 

traditional paper charts that NOAA will 

maintain is determined. The plan for 

transitioning away from the traditional 

NOAA paper charts is available in the 

‘‘Sunsetting Traditional NOAA Paper 

Charts’’ document found on the 

following website: https://

nauticalcharts.noaa.gov/publications/ 

docs/raster-sunset.pdf. 

To maintain a healthy market that 

meets the needs of recreational and 

commercial mariners, Coast Survey is 

suspending the certifications for new, 

non-certified printers of charts while 

continuing to maintain certification of 

printers who continue to meet standards 

as provided under their current 

agreements. There are currently eight 

certified printers of the Coast Pilot. 

Coast Survey feels the market can bear 

no more that 10 of these printers. Once 

there are 10 certified printers of the 

Coast Pilot, Coast Survey will suspend 

the certifications for new, non-certified 

printers of the Coast Pilot. 

DATES: Send comments on or before 

February 9, 2021. 

ADDRESSES: Comments can be submitted 

online to the Office of Coast Survey’s 

inquiry system, ASSIST, at the 

following site https://

www.nauticalcharts.noaa.gov/customerservice/assist/. 

FOR FURTHER INFORMATION CONTACT: 

Matthew Kroll, Deputy Chief, 

Navigation Services Division, NOAA’s 

Office of Coast Survey at matt.kroll@

noaa.gov, 240–533–0063 

SUPPLEMENTARY INFORMATION: NOAA 

privatized the printing of nautical charts 

in October 2013. In January 2014, Coast 

Survey started soliciting private 

companies to apply for NOAA 

certification to print, sell, and distribute 

paper nautical charts that NOAA’s 

National Ocean Service considered 

‘‘published’’, and that therefore meet 

carriage requirements. After review, 

Coast Survey certifies applicants who 

meet all NOAA chart standards. 

At the time of Coast Survey’s January 

2014 solicitation, NOAA had two 

certified printing agents. As of October 

29, 2020, NOAA had 36 certified agents 

found here, https://

nauticalcharts.noaa.gov/publications/ 

print-agents.html#paper-charts, with 

two additional companies under review. 

Coast Survey has concluded that the 

current certified printers are meeting 

market needs, and that the companies 

with pending applications for 

certification will adequately fill any 

additional market openings. Therefore, 

until further notice, Coast Survey will 

not accept any new applications for 

certification, except for printers of the 

Coast Pilot until 10 Coast Pilot printers 

has been achieved. 

Coast Survey began the transition 

away from traditional paper products 

and considers the NOAA ENC as its 

primary product to meet navigation 

needs, and makes the following 

resources available: 

1. NOAA’s electronic navigational

charts (NOAA ENC®) (https://

nauticalcharts.noaa.gov/charts/noaaenc.html) are available for free 

download. 

2. See Coast Survey’s plan to improve

the ENC, ‘‘Transforming the NOAA 

ENC.’’ (https://nauticalcharts.noaa.gov/ 

publications/docs/enctransformation.pdf). 

3. United States Coast Pilot (https://

nauticalcharts.noaa.gov/publications/ 

coast-pilot/index.html) is available 

online in a digital format. 

4. NOAA’s Custom Chart tool (https://

devgis.charttools.noaa.gov/pod/) gives 

the user the ability to create and 

download charts based on your own 

scale, extent, and paper size settings. 

The National Charting Plan outlines 

several improvements to chart content 

(https://nauticalcharts.noaa.gov/charts/ 

docs/NCP-1-pager-v2.pdf). 

Authority: 33 U.S.C. Chapter 17, Coast and 

Geodetic Survey Act of 1947. 

Shepard M. Smith, 

Director, Office of Coast Survey, National 

Ocean Service, National Oceanic and 

Atmospheric Administration. 

[FR Doc. 2020–27344 Filed 12–10–20; 8:45 am] 

BILLING CODE 3510–JE–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XA687] 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to Naval Base San 

Diego Pier 6 Replacement Project, San 

Diego, California 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

harassment authorization; request for 

comments on proposed authorization 

and possible renewal. 

SUMMARY: NMFS has received a request 

from the U.S. Navy (Navy) for 

authorization to take marine mammals 

incidental to the Naval Base San Diego 

Pier 6 Replacement Project in San 

Diego, California. Pursuant to the 

Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue an incidental 

harassment authorization (IHA) to 

incidentally take marine mammals 

during the specified activities. NMFS is 

also requesting comments on a possible 

one-year renewal that could be issued 

under certain circumstances and if all 

requirements are met, as described in 

Request for Public Comments at the end 

of this notice. NMFS will consider 

public comments prior to making any 

final decision on the issuance of the 

requested MMPA authorizations and 

agency responses will be summarized in 

the final notice of our decision. 

DATES: Comments and information must 

be received no later than January 11, 

2021. 

ADDRESSES: Comments should be 

addressed to Jolie Harrison, Chief, 

Permits and Conservation Division, 

Office of Protected Resources, National 

Marine Fisheries Service and should be 

sent to ITP.Meadows@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 online at 

https://www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-underVerDate Sep<11>2014 23:25 Dec 10, 2020 Jkt 253001 PO 00000 Frm 00038 Fmt 4703 Sfmt 4703 E:\FR\FM\11DEN1.SGM 11DEN1

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80028 Federal Register / Vol. 85, No. 239 / Friday, December 11, 2020 / Notices 

marine-mammal-protection-act 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: 

Dwayne Meadows, Ph.D., Office of 

Protected Resources, NMFS, (301) 427– 

8401. Electronic copies of the 

application and supporting documents, 

as well as a list of the references cited 

in this document, may be obtained 

online at: https://

www.fisheries.noaa.gov/permit/

incidental-take-authorizations-undermarine-mammal-protection-act. In case 

of problems accessing these documents, 

please call the contact listed above. 

SUPPLEMENTARY INFORMATION: 

Background 

The MMPA prohibits the ‘‘take’’ of 

marine mammals, with certain 

exceptions. Sections 101(a)(5)(A) and 

(D) of the MMPA (16 U.S.C. 1361 et

seq.) direct the Secretary of Commerce

(as delegated to NMFS) to allow, upon

request, the incidental, but not

intentional, taking of small numbers of

marine mammals by U.S. citizens who

engage in a specified activity (other than

commercial fishing) within a specified

geographical region if certain findings

are made and either regulations are

issued or, if the taking is limited to

harassment, a notice of a proposed

incidental take authorization may be

provided to the public for review.

Authorization for incidental takings 

shall be granted if NMFS finds that the 

taking will have a negligible impact on 

the species or stock(s) and will not have 

an unmitigable adverse impact on the 

availability of the species or stock(s) for 

taking for subsistence uses (where 

relevant). Further, NMFS must prescribe 

the permissible methods of taking and 

other ‘‘means of effecting the least 

practicable adverse impact’’ on the 

affected species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance, and on the 

availability of the species or stocks for 

taking for certain subsistence uses 

(referred to in shorthand as 

‘‘mitigation’’); and requirements 

pertaining to the mitigation, monitoring 

and reporting of the takings are set forth. 

The definitions of all applicable 

MMPA statutory terms cited above are 

included in the relevant sections below. 

National Environmental Policy Act 

To comply with the National 

Environmental Policy Act of 1969 

(NEPA; 42 U.S.C. 4321 et seq.) and 

NOAA Administrative Order (NAO) 

216–6A, NMFS must review our 

proposed action (i.e., the issuance of an 

IHA) with respect to potential impacts 

on the human environment. 

This action is consistent with 

categories of activities identified in 

Categorical Exclusion B4 (IHAs with no 

anticipated serious injury or mortality) 

of the Companion Manual for NOAA 

Administrative Order 216–6A, which do 

not individually or cumulatively have 

the potential for significant impacts on 

the quality of the human environment 

and for which we have not identified 

any extraordinary circumstances that 

would preclude this categorical 

exclusion. Accordingly, NMFS has 

preliminarily determined that the 

issuance of the proposed IHA qualifies 

to be categorically excluded from 

further NEPA review. 

We will review all comments 

submitted in response to this notice 

prior to concluding our NEPA process 

or making a final decision on the IHA 

request. 

Summary of Request 

On July 14, 2020, NMFS received an 

application from the Navy requesting an 

IHA to take small numbers of California 

sea lions incidental to pile driving and 

removal associated with the Naval Base 

San Diego Pier 6 Replacement Project. 

The application was deemed adequate 

and complete on November 25, 2020. 

The Navy’s request is for take of a small 

number of California sea lions by Level 

B harassment. Neither the Navy nor 

NMFS expects serious injury or 

mortality to result from this activity, 

and therefore, an IHA is appropriate. 

Description of Proposed Activity 

Overview 

The purpose of the project is to 

remove and replace a decaying and 

inadequate pier for Navy ships. 

Specifically, in-water construction work 

includes removing the existing pier (by 

vibratory pile extraction, water jetting, 

hydraulic underwater chainsaw, direct 

pulling, and/or pile clippers) consisting 

of a total of 1,998 12 to 24-inch piles, 

after removing above water structures 

and utilities. Once demolition has 

opened up space, construction will 

begin in the same location on a new pier 

measuring 37 m (120 ft) wide by 457 m 

(1,500 ft) long. New construction work 

involves impact driving of 966 piles. 

This includes 528 24-inch structural 

concrete piles, 208 24-inch concrete 

fender piles, 4 20-inch piles for a loadout ramp, and 226 16-inch fiberglass 

secondary and corner fender piles. Pile 

driving/removal is expected to take no 

more than 250 days. Pile driving would 

be by vibratory pile driving until 

resistance is too great and driving would 

switch to an impact hammer. 

The pile driving/removal can result in 

take of marine mammals from sound in 

the water which results in behavioral 

harassment or auditory injury. 

Dates and Duration 

The work described here is scheduled 

for October 1, 2021 through September 

30, 2022. In-water activities are planned 

for daylight hours only. 

Specific Geographic Region 

The activities would occur in the 

south-central portion of San Diego Bay 

(Figure 1). San Diego Bay is a narrow, 

crescent-shaped natural embayment 

oriented northwest-southeast with an 

approximate length of 24 kilometers 

(km) (15 miles (mi)) and a total area of 

roughly 4 km2 (11,000 acres; Port of San 

Diego, 2007). The width of the Bay 

ranges from 0.3 to 5.8 km (0.2 to 3.6 mi), 

and depths range from 23 m (74 ft) 

Mean Lower Low Water (MLLW) near 

the tip of Ballast Point to less than 1.2 

m (4 ft) at the southern end (Merkel and 

Associates, Inc., 2009). Approximately 

half of the Bay is less than 4.5 meters 

(m) (15 feet (ft)) deep and much of it is

less than 15 m (50 ft) deep (Merkel and

Associates, Inc., 2009). The northern

and central portions of the Bay have

been shaped by historical dredging and

filling to support large ship navigation

and shoreline development. The United

States Army Corps of Engineers dredges

the main navigation channel in the Bay

to maintain a depth of 14 m (47 ft)

MLLW and is responsible for providing

safe transit for private, commercial, and

military vessels within the bay (NOAA

2012). Outside of the navigation

channel, the bay floor consists of

platforms at depths that vary slightly

(Merkel and Associates, Inc., 2009).

Within the Central Bay, typical depths

range from 10.7–11.6 m (35–38 ft)

MLLW to support large ship turning and

anchorage, and small vessel marinas are

typically dredged to depths of 4.6 m (15

ft) MLLW (Merkel and Associates, Inc.,

2009).


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San Diego Bay is heavily used by 

commercial, recreational, and military 

vessels, with an average of 82,413 vessel 

movements (in or out of the Bay) per 

year (approximately 225 vessel transits 

per day), a majority of which are 

presumed to occur during daylight 

hours. This number of transits does not 

include recreational boaters that use San 

Diego Bay, estimated to number 200,000 

annually (San Diego Harbor Safety 

Committee, 2009). Background 

(ambient) noise in the south-central San 

Diego Bay averaged 126 decibels (dB) in 

2019 (Dahl and Dall’Osto 2019). Noise 

from non-impulsive sources associated 

with the proposed activities is, therefore 

assumed to become indistinguishable 

from background noise as it diminishes 

to 126 dB re: 1 micropascal (mPa) with 

distance from the source (Dahl and 

Dall’Osto, 2019). 

Section 2.2 of the application 

provides extensive additional details 

about the project area. 

Detailed Description of Specific Activity 

The purpose of the project is to 

remove and replace a decaying and 

inadequate pier built in 1945 that is 

now too narrow, structurally weakened 

and decaying. A new, wider pier is 

needed to provide adequate ship 

berthing infrastructure to support 

modern Navy ships and fleet readiness. 

The Navy will abate any hazardous 

materials, and then disconnect and 

remove all utilities and mechanical 

equipment from the old pier. After the 

old pier deck and associated structures 

are removed, the exiting 1,998 in-water 

piles will be removed. Existing piles 

include 1,833 20 or 24-inch concrete 

piles, 149 12-inch timber-plastic 

composite piles, and 16 16-inch steel I 

piles (Table 1). Workers would initially 

attempt to remove the piles by dead-pull 

with or without water jetting the pile 

(where an external high-pressure water 

jet is used to loosen the sediment 

around the pile). A vibratory hammer 

may also be used to loosen the piles 

prior to removal. If a pile cannot be 

removed by these methods, workers 

would use a hydraulic cutter or 

underwater hydraulic chainsaw to cut 

the piles at the mudline. Once the piles 

are cut, a crane would remove the pile 

and set it onto a barge for transport to 

a concrete processing yard. The Navy 

expects to be able to remove up to 8 

piles per day, meaning 250 days of work 

will be required to remove all old piles. 

Once demolition has opened up 

space, construction will begin in the 

same location on the new pier. New 

construction work involves vibratory 

and impact driving of 966 piles (Table 


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80030 Federal Register / Vol. 85, No. 239 / Friday, December 11, 2020 / Notices 

1). This includes 528 24-inch structural 

concrete piles, 208 24-inch concrete 

fender piles, 4 20-inch piles for a loadout ramp, and 226 16-inch fiberglass 

secondary and corner fender piles. Pile 

driving/removal is expected to take no 

more than 250 days. Pile driving would 

be by impact hammer only. The total 

length of the piles would range from 

approximately 26 m (85 ft) (fender piles) 

to 34 m (110 ft) (structural piles); the 

length of the portion of the piles in the 

water column would range from 

approximately 3 to 9 m (10 to 30 ft), 

depending on pile type, location, and 

tide. The Navy estimates they will 

install 7 piles per day, meaning in-water 

construction will take 138 days. 

It is anticipated that overlap between 

demolition and installation activities 

would occur over the 250-day project 

period. Pile removal would begin on 

day 1 while pile installation is 

anticipated to begin after removal of one 

third of the piles (after approximately 83 

days of pile removal). Pile installation is 

expected to periodically occur alongside 

ongoing pile removal activities over 138 

days of the remaining 167 project days 

of pile removal. Because pile 

installation cannot continue where 

demolition activities are incomplete, 

there would be 29 days (167 days—138 

days of pile installation) where only pile 

removal would occur after pile 

installation has started. In summary, the 

250-day project period would include 

112 days of pile removal-only activities 

and 138 days of concurrent pile removal 

and installation activities. There may be 

simultaneous use of no more than two 

of the various pile extraction methods 

(pile clippers, water jetting, underwater 

chainsaws or vibratory pile removal) 

during pile removal. 

The pile driving equipment will be 

deployed and operated from barges, on 

water. Materials will be delivered on 

barges. 

TABLE 1—SUMMARY OF PILE DRIVING ACTIVITIES

Method Pile type Number of 

piles Piles/day Total estimated days 

Demolition of Existing Pier 

Vibratory Extraction High-pressure Water 

Jetting Hydraulic Pile Clipper Hydraulic 

Chainsaw.

24-inch square pre-cast concrete, 20-inch 

square pre-stressed/pre-cast concrete 

piles.

1,833 8 250 

12-inch composite (timber-plastic) piles ........ 149 

Vibratory Extraction ......................................... 16-inch I-shaped steel piles ........................... 16 

Total ...................................................................................................................................... 1,998 

Construction of New Pier 

Impact Pile Driving .......................................... 24-inch octagonal concrete structural test 

piles.

15 7 138 

24-inch octagonal concrete structural piles ... 513 

24-inch square concrete fender system test 

piles.

4 

24-inch square concrete primary fender piles 204 

20-inch square concrete pile for load-out 

ramp cradle.

4 

16-inch fiberglass secondary and corner 

fender piles.

226 

High-pressure Water Jetting ........................... 20- and 24-inch concrete piles ...................... Within Above Counts 

Total ...................................................................................................................................... 966 

Proposed mitigation, monitoring, and 

reporting measures are described in 

detail later in this document (please see 

Proposed Mitigation and Proposed 

Monitoring and Reporting). 

Description of Marine Mammals in 

the Area of Specified Activities 

Sections 3 and 4 of the application 

summarize available information 

regarding status and trends, distribution 

and habitat preferences, and behavior 

and life history, of the potentially 

affected species. Additional information 

regarding population trends and threats 

may be found in NMFS’s Stock 

Assessment Reports (SARs; https://

www.fisheries.noaa.gov/national/

marine-mammal-protection/marinemammal-stock-assessments) and more 

general information about these species 

(e.g., physical and behavioral 

descriptions) may be found on NMFS’s 

website (https://

www.fisheries.noaa.gov/find-species). 

Table 2 lists all species with expected 

potential for occurrence in the project 

area in San Diego Bay and summarizes 

information related to the population or 

stock, including regulatory status under 

the MMPA and Endangered Species Act 

(ESA) and potential biological removal 

(PBR), where known. For taxonomy, we 

follow Committee on Taxonomy (2020). 

PBR is 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 (as described in NMFS’s 

SARs). While no mortality is anticipated 

or authorized here, PBR and annual 

serious injury and mortality from 

anthropogenic sources are included here 


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Federal Register / Vol. 85, No. 239 / Friday, December 11, 2020 / Notices 80031 

as gross indicators of the status of the 

species and other threats. 

Marine mammal abundance estimates 

presented in this document represent 

the total number of individuals that 

make up a given stock or the total 

number estimated within a particular 

study or survey area. NMFS’s stock 

abundance estimates for most species 

represent the total estimate of 

individuals within the geographic area, 

if known, that comprises that stock. For 

some species, this geographic area may 

extend beyond U.S. waters. All managed 

stocks in this region are assessed in 

NMFS’s U.S. Pacific SARs (e.g., Caretta 

et al., 2020). 

TABLE 2—SPECIES THAT SPATIALLY CO-OCCUR WITH THE ACTIVITY TO THE DEGREE THAT TAKE IS REASONABLY LIKELY

TO OCCUR

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

Strategic 

(Y/N) 1

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 2

PBR Annual 

M/SI3

Order Carnivora—Superfamily Pinnipedia 

Family Otariidae (eared 

seals and sea lions): 

California Sea Lion ...... Zalophus californianus United States ............. -, -, N 257,606 (N/A, 233,515, 

2014).

14,011 >321 

1—Endangered Species Act (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 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—NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. 3—These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined 

(e.g., commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value 

or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases. 

California sea lions (Zalophus 

californianus) spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur, and we have 

proposed authorizing take of this 

species. Other marine mammal species 

observed in San Diego Bay are the 

coastal bottlenose dolphin (Tursiops 

truncatus), which is regularly seen in 

the North Bay; Pacific harbor seal 

(Phoca vitulina), which frequently 

enters the North Bay; and common 

dolphins (Delphinus spp.), which are 

rare visitors in the North Bay. Gray 

whales (Eschrichtius robustus) are 

occasionally sighted near the mouth of 

San Diego Bay during their winter 

migration (Naval Facilities Engineering 

Command, Southwest and Port of San 

Diego Bay, 2013). Based on many years 

of observations and numerous Navyfunded surveys in San Diego Bay 

(Merkel and Associates, Inc., 2008; 

Sorensen and Swope, 2010; Graham and 

Saunders, 2014; Tierra Data Inc., 2016), 

these other marine mammals rarely 

occur south of the Coronado Bay Bridge, 

are not known to occur near Naval Base 

San Diego, and any occurrence in the 

project area would be very rare. 

Therefore, while coastal bottlenose 

dolphins, Pacific harbor seals, common 

dolphins, and gray whales have been 

reported in San Diego Bay, they are not 

anticipated to occur in the project area 

and no take of these species is 

anticipated or proposed to be 

authorized. 

California Sea Lion 

California sea lions occur from 

Vancouver Island, British Columbia, to 

the southern tip of Baja California. Sea 

lions breed on the offshore islands of 

southern and central California from 

May through July (Heath and Perrin, 

2008). During the non-breeding season, 

adult and subadult males and juveniles 

migrate northward along the coast to 

central and northern California, Oregon, 

Washington, and Vancouver Island 

(Jefferson et al., 1993). They return 

south the following spring (Heath and 

Perrin 2008, Lowry and Forney 2005). 

Females and some juveniles tend to 

remain closer to rookeries (Antonelis et 

al., 1990; Melin et al., 2008). 

Pupping occurs primarily on the 

California Channel Islands from late 

May until the end of June (Peterson and 

Bartholomew 1967). Weaning and 

mating occur in late spring and summer 

during the peak upwelling period 

(Bograd et al., 2009). After the mating 

season, adult males migrate northward 

to feeding areas as far away as the Gulf 

of Alaska (Lowry et al., 1992), and they 

remain away until spring (March–May), 

when they migrate back to the breeding 

colonies. Adult females generally 

remain south of Monterey Bay, 

California throughout the year, feeding 

in coastal waters in the summer and 

offshore waters in the winter, 

alternating between foraging and 

nursing their pups on shore until the 

next pupping/breeding season (Melin 

and DeLong, 2000; Melin et al., 2008). 

In San Diego Bay, California sea lions 

regularly occur on rocks, buoys and 

other structures, and especially on bait 

barges. California sea lion occurrence in 

the project area is expected to be rare 

based on sighting of only two 

individuals in the water off of Navy 

Base San Diego during one 2010 survey 

(Sorensen and Swope, 2010). Different 

age classes of California sea lions are 

found in the San Diego region 

throughout the year (Lowry et al., 1991). 

Although adult male California sea lions 

feed in areas north of San Diego, 

animals of all other ages and sexes 

spend most, but not all, of their time 

feeding at sea during winter. During 

warm-water months, a high proportion 

of the adult males and females are 

hauled-out at terrestrial sites. 

Marine Mammal Hearing 

Hearing is the most important sensory 

modality for marine mammals 

underwater, and exposure to 

anthropogenic sound can have 

deleterious effects. To appropriately 

assess the potential effects of exposure 

to sound, 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 


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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 directly measured or estimated 

hearing ranges on the basis of available 

behavioral response data, audiograms 

derived using auditory evoked potential 

techniques, anatomical modeling, and 

other data. Note that no direct 

measurements of hearing ability have 

been successfully completed for 

mysticetes (i.e., low-frequency 

cetaceans). Subsequently, NMFS (2018) 

described generalized hearing ranges for 

these marine mammal hearing groups. 

Generalized hearing ranges were chosen 

based on the approximately 65 decibel 

(dB) threshold from the normalized 

composite audiograms, with the 

exception for lower limits for lowfrequency cetaceans where the lower 

bound was deemed to be biologically 

implausible and the lower bound from 

Southall et al. (2007) retained. Marine 

mammal hearing groups and their 

associated hearing ranges are provided 

in Table 3. 

TABLE 3—MARINE MAMMAL HEARING GROUPS

[NMFS, 2018] 

Hearing group Generalized hearing 

range * 

Low-frequency (LF) cetaceans (baleen whales) ..................................................................................................................... 7 Hz to 35 kHz. 

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) ........................................... 150 Hz to 160 kHz. 

High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, cephalorhynchid, Lagenorhynchus cruciger & L. 

australis).

275 Hz to 160 kHz. 

Phocid pinnipeds (PW) (underwater)(true seals) .................................................................................................................... 50 Hz to 86 kHz. 

Otariid pinnipeds (OW) (underwater)(sea lions and fur seals) ............................................................................................... 60 Hz to 39 kHz. 

* Represents the generalized hearing range for the entire group as a composite (i.e., all species within the group), where individual species’ 

hearing ranges are typically not as broad. Generalized hearing range chosen based on ∼65 dB threshold from normalized composite audiogram, 

with the exception for lower limits for LF cetaceans (Southall et al., 2007) and PW pinniped (approximation). 

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 

(Hemila ̈ et al., 2006; Kastelein et al., 

2009; Reichmuth and Holt, 2013). 

For more detail concerning these 

groups and associated frequency ranges, 

please see NMFS (2018) for a review of 

available information. California sea 

lions are in the otariid family group. 

Potential Effects of Specified Activities 

on Marine Mammals and their Habitat 

This section includes a summary and 

discussion of the ways that components 

of the specified activity may impact 

marine mammals and their habitat. The 

Estimated Take section later in this 

document includes a quantitative 

analysis of the number of individuals 

that are expected to be taken by this 

activity. The Negligible Impact Analysis 

and Determination section considers the 

content of this section, the Estimated 

Take section, and the Proposed 

Mitigation section, to draw conclusions 

regarding the likely impacts of these 

activities on the reproductive success or 

survivorship of individuals and how 

those impacts on individuals are likely 

to impact marine mammal species or 

stocks. 

Acoustic effects on marine mammals 

during the specified activity can occur 

from vibratory and impact pile driving/ 

removal and underwater chainsaws, pile 

clippers and water jetting. The effects of 

underwater noise from the Navy’s 

proposed activities have the potential to 

result in Level A or Level B harassment 

of marine mammals in the action area. 

Description of Sound Sources 

The marine soundscape is comprised 

of both ambient and anthropogenic 

sounds. Ambient sound is defined as 

the all-encompassing sound in a given 

place and is usually a composite of 

sound from many sources both near and 

far (ANSI 1994, 1995). The sound level 

of an area is defined by the total 

acoustical energy being generated by 

known and unknown sources. These 

sources may include physical (e.g., 

waves, wind, precipitation, earthquakes, 

ice, atmospheric sound), biological (e.g., 

sounds produced by marine mammals, 

fish, and invertebrates), and 

anthropogenic sound (e.g., vessels, 

dredging, aircraft, construction). 

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. 

In-water construction activities 

associated with the project would 

include impact pile driving and 

vibratory pile removal as well as water 

jetting, underwater chainsaws, and pile 

clippers. The sounds produced by these 

activities fall into one of two general 

sound types: Impulsive and nonimpulsive. Impulsive sounds (e.g., 

explosions, gunshots, sonic booms, 

impact pile driving) are typically 

transient, brief (less than 1 second), 

broadband, and consist of high peak 

sound pressure with rapid rise time and 

rapid decay (ANSI, 1986; NIOSH, 1998; 

ANSI, 2005; NMFS, 2018). Nonimpulsive sounds (e.g., machinery 

operations such as drilling or dredging, 

vibratory pile driving, water jetting, 

chainsaws, pile clippers, and active 

sonar systems) can be broadband, 

narrowband or tonal, brief or prolonged 

(continuous or intermittent), and 

typically do not have the high peak 

sound pressure with raid rise/decay 

time that impulsive sounds do (ANSI 

1995; NIOSH 1998; NMFS 2018). 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). 


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Two types of pile hammers would be 

used on this project: impact and 

vibratory. 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 Sound pressure 

Levels (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). 

Pile clippers and underwater 

chainsaws are hydraulically operated 

equipment. A pile clipper is a large, 

heavy elongated horizontal guillotinelike structure that is mechanically 

lowered over a pile down to the 

mudline or substrate where hydraulic 

force is used to push a sharp blade to 

cut a pile. The underwater chainsaws 

are operated by SCUBA divers. Water jet 

systems use very high pressure jets of 

water to move and even cut materials. 

Sounds generated by this demolition 

equipment are non-impulsive and 

continuous (NAVAC Southwest, 2020) 

The likely or possible impacts of the 

Navy’s proposed activity on marine 

mammals could involve both nonacoustic and acoustic stressors. 

Potential non-acoustic stressors could 

result from the physical presence of the 

equipment and personnel; however, any 

impacts to marine mammals are 

expected to primarily be acoustic in 

nature. Acoustic stressors include 

effects of heavy equipment operation 

during pile installation and removal. 

Acoustic Impacts 

The introduction of anthropogenic 

noise into the aquatic environment from 

pile driving and removal and the 

various demolition equipment is the 

primary means by which marine 

mammals may be harassed from the 

Navy’s specified activity. In general, 

animals exposed to natural or 

anthropogenic sound may experience 

physical and psychological effects, 

ranging in magnitude from none to 

severe (Southall et al., 2007). Generally, 

exposure to pile driving and removal 

and other construction noise has the 

potential to result in auditory threshold 

shifts and behavioral reactions (e.g., 

avoidance, temporary cessation of 

foraging and vocalizing, changes in dive 

behavior). Exposure to anthropogenic 

noise can also lead to non-observable 

physiological responses such an 

increase in stress hormones. Additional 

noise in a marine mammal’s habitat can 

mask acoustic cues used by marine 

mammals to carry out daily functions 

such as communication and predator 

and prey detection. The effects of pile 

driving and demolition noise on marine 

mammals are dependent on several 

factors, including, but not limited to, 

sound type (e.g., impulsive vs. nonimpulsive), the species, age and sex 

class (e.g., adult male vs. mom with 

calf), duration of exposure, the distance 

between the pile and the animal, 

received levels, behavior at time of 

exposure, and previous history with 

exposure (Wartzok et al., 2004; Southall 

et al., 2007). Here we discuss physical 

auditory effects (threshold shifts) 

followed by behavioral effects and 

potential impacts on habitat. 

NMFS defines a noise-induced 

threshold shift (TS) as a change, usually 

an increase, in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level (NMFS, 2018). The amount of 

threshold shift is customarily expressed 

in dB. A TS can be permanent or 

temporary. As described in NMFS 

(2018), there are numerous factors to 

consider when examining the 

consequence of TS, including, but not 

limited to, the signal temporal pattern 

(e.g., impulsive or non-impulsive), 

likelihood an individual would be 

exposed for a long enough duration or 

to a high enough level to induce a TS, 

the magnitude of the TS, time to 

recovery (seconds to minutes or hours to 

days), the frequency range of the 

exposure (i.e., spectral content), the 

hearing and vocalization frequency 

range of the exposed species relative to 

the signal’s frequency spectrum (i.e., 

how animal uses sound within the 

frequency band of the signal; e.g., 

Kastelein et al., 2014), and the overlap 

between the animal and the source (e.g., 

spatial, temporal, and spectral). 

Permanent Threshold Shift (PTS)— 

NMFS defines PTS as a permanent, 

irreversible increase in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level (NMFS 2018). Available data from 

humans and other terrestrial mammals 

indicate that a 40 dB threshold shift 

approximates PTS onset (see Ward et 

al., 1958, 1959; Ward, 1960; Kryter et 

al., 1966; Miller, 1974; Ahroon et al., 

1996; Henderson and Hu, 2008). PTS 

levels for marine mammals are 

estimates, with the exception of a single 

study unintentionally inducing PTS in a 

harbor seal (Kastak et al., 2008), there 

are no empirical data measuring PTS in 

marine mammals, largely due to the fact 

that, for various ethical reasons, 

experiments involving anthropogenic 

noise exposure at levels inducing PTS 

are not typically pursued or authorized 

(NMFS, 2018). 

Temporary Threshold Shift (TTS)—A 

temporary, reversible increase in the 

threshold of audibility at a specified 

frequency or portion of an individual’s 

hearing range above a previously 

established reference level (NMFS, 

2018). Based on data from cetacean TTS 

measurements (see Southall et al., 

2007), a TTS of 6 dB is considered the 

minimum threshold shift clearly larger 

than any day-to-day or session-tosession variation in a subject’s normal 

hearing ability (Schlundt et al., 2000; 

Finneran et al., 2000, 2002). As 

described in Finneran (2016), marine 

mammal studies have shown the 

amount of TTS increases with 

cumulative sound exposure level 

(SELcum) in an accelerating fashion: At 

low exposures with lower SELcum, the 

amount of TTS is typically small and 

the growth curves have shallow slopes. 

At exposures with higher SELcum, the 

growth curves become steeper and 

approach linear relationships with the 

noise SEL. 

Depending on the degree (elevation of 

threshold in dB), duration (i.e., recovery 

time), and frequency range of TTS, and 

the context in which it is experienced, 

TTS can have effects on marine 

mammals ranging from discountable to 

serious (similar to those discussed in 

auditory masking, below). For example, 

a marine mammal may be able to readily 

compensate for a brief, relatively small 

amount of TTS in a non-critical 

frequency range that takes place during 

a time when the animal is traveling 

through the open ocean, where ambient 

noise is lower and there are not as many 

competing sounds present. 

Alternatively, a larger amount and 

longer duration of TTS sustained during 

time when communication is critical for 

successful mother/calf interactions 

could have more serious impacts. We 

note that reduced hearing sensitivity as 

a simple function of aging has been 

observed in marine mammals, as well as 

humans and other taxa (Southall et al., 

2007), so we can infer that strategies 

exist for coping with this condition to 

some degree, though likely not without 

cost. 

Currently, TTS data only exist for four 

species of cetaceans (bottlenose 


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dolphin, beluga whale (Delphinapterus 

leucas), harbor porpoise, and Yangtze 

finless porpoise (Neophocoena 

asiaeorientalis)) and five species of 

pinnipeds exposed to a limited number 

of sound sources (i.e., mostly tones and 

octave-band noise) in laboratory settings 

(Finneran, 2015). TTS was not observed 

in trained spotted (Phoca largha) and 

ringed (Pusa hispida) seals exposed to 

impulsive noise at levels matching 

previous predictions of TTS onset 

(Reichmuth et al., 2016). In general, 

harbor seals and harbor porpoises have 

a lower TTS onset than other measured 

pinniped or cetacean species (Finneran, 

2015). The potential for TTS from 

impact pile driving exists. After 

exposure to playbacks of impact pile 

driving sounds (rate 2760 strikes/hour) 

in captivity, mean TTS increased from 

0 dB after 15 minute exposure to 5 dB 

after 360 minute exposure; recovery 

occurred within 60 minutes (Kastelein 

et al., 2016). Additionally, the existing 

marine mammal TTS data come from a 

limited number of individuals within 

these species. No data are available on 

noise-induced hearing loss for 

mysticetes. For summaries of data on 

TTS in marine mammals or for further 

discussion of TTS onset thresholds, 

please see Southall et al. (2007), 

Finneran and Jenkins (2012), Finneran 

(2015), and Table 5 in NMFS (2018). 

Installing piles requires impact pile 

driving. There would likely be pauses in 

activities producing the sound during 

each day. Given these pauses and that 

many marine mammals are likely 

moving through the action area and not 

remaining for extended periods of time, 

the potential for TS declines. 

Behavioral Harassment - Exposure to 

noise from pile driving and removal also 

has the potential to behaviorally disturb 

marine mammals. Available studies 

show wide variation in response to 

underwater sound; therefore, it is 

difficult to predict specifically how any 

given sound in a particular instance 

might affect marine mammals 

perceiving the signal. If a marine 

mammal does react briefly to an 

underwater sound by changing its 

behavior or moving a small distance, the 

impacts of the change are unlikely to be 

significant to the individual, let alone 

the stock or population. However, if a 

sound source displaces marine 

mammals from an important feeding or 

breeding area for a prolonged period, 

impacts on individuals and populations 

could be significant (e.g., Lusseau and 

Bejder, 2007; Weilgart, 2007; NRC, 

2005). 

Disturbance may result in 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. 

Pinnipeds may increase their haul out 

time, possibly to avoid in-water 

disturbance (Thorson and Reyff, 2006). 

Behavioral responses to sound are 

highly variable and context-specific and 

any reactions depend on numerous 

intrinsic and extrinsic factors (e.g., 

species, state of maturity, experience, 

current activity, reproductive state, 

auditory sensitivity, time of day), as 

well as the interplay between factors 

(e.g., Richardson et al., 1995; Wartzok et 

al., 2004; Southall et al., 2007; Weilgart, 

2007; Archer et al., 2010). Behavioral 

reactions can vary not only among 

individuals but also within an 

individual, depending on previous 

experience with a sound source, 

context, and numerous other factors 

(Ellison et al., 2012), and can vary 

depending on characteristics associated 

with the sound source (e.g., whether it 

is moving or stationary, number of 

sources, distance from the source). In 

general, pinnipeds seem more tolerant 

of, or at least habituate more quickly to, 

potentially disturbing underwater sound 

than do cetaceans, and generally seem 

to be less responsive to exposure to 

industrial sound than most cetaceans. 

Please see Appendices B and C of 

Southall et al. (2007) for a review of 

studies involving marine mammal 

behavioral responses to sound. 

Disruption of feeding behavior can be 

difficult to correlate with anthropogenic 

sound exposure, so it is usually inferred 

by observed displacement from known 

foraging areas, the appearance of 

secondary indicators (e.g., bubble nets 

or sediment plumes), or changes in dive 

behavior. As for other types of 

behavioral response, the frequency, 

duration, and temporal pattern of signal 

presentation, as well as differences in 

species sensitivity, are likely 

contributing factors to differences in 

response in any given circumstance 

(e.g., Croll et al., 2001; Nowacek et al., 

2004; Madsen et al., 2006; Yazvenko et 

al., 2007). A determination of whether 

foraging disruptions incur fitness 

consequences would require 

information on or estimates of the 

energetic requirements of the affected 

individuals and the relationship 

between prey availability, foraging effort 

and success, and the life history stage of 

the animal. 

In 2016, the Alaska Department of 

Transportation and Public Facilities 

(ADOT&PF) documented observations 

of marine mammals during construction 

activities (i.e., pile driving) at the 

Kodiak Ferry Dock (see 80 FR 60636, 

October 7, 2015). In the marine mammal 

monitoring report for that project (ABR 

2016), 1,281 Steller sea lions were 

observed within the Level B disturbance 

zone during pile driving or drilling (i.e., 

documented as Level B harassment 

take). Of these, 19 individuals 

demonstrated an alert behavior, 7 were 

fleeing, and 19 swam away from the 

project site. All other animals (98 

percent) were engaged in activities such 

as milling, foraging, or fighting and did 

not change their behavior. In addition, 

two sea lions approached within 20 

meters of active vibratory pile driving 

activities. Three harbor seals were 

observed within the disturbance zone 

during pile driving activities; none of 

them displayed disturbance behaviors. 

Fifteen killer whales and three harbor 

porpoise were also observed within the 

Level B harassment zone during pile 

driving. The killer whales were 

travelling or milling while all harbor 

porpoises were travelling. No signs of 

disturbance were noted for either of 

these species. Given the similarities in 

activities and habitat, we expect similar 

behavioral responses of marine 

mammals to the Navy’s specified 

activity. That is, disturbance, if any, is 

likely to be temporary and localized 

(e.g., small area movements). 

Stress responses—An animal’s 

perception of a threat may be sufficient 

to trigger stress responses consisting of 

some combination of behavioral 

responses, autonomic nervous system 

responses, neuroendocrine responses, or 

immune responses (e.g., Seyle 1950; 

Moberg 2000). In many cases, an 

animal’s first and sometimes most 

economical (in terms of energetic costs) 

response is behavioral avoidance of the 

potential stressor. Autonomic nervous 

system responses to stress typically 

involve changes in heart rate, blood 

pressure, and gastrointestinal activity. 

These responses have a relatively short 

duration and may or may not have a 

significant long-term effect on an 

animal’s fitness. 

Neuroendocrine stress responses often 

involve the hypothalamus-pituitaryadrenal system. Virtually all 

neuroendocrine functions that are 

affected by stress—including immune 

competence, reproduction, metabolism, 

and behavior—are regulated by pituitary 

hormones. Stress-induced changes in 

the secretion of pituitary hormones have 

been implicated in failed reproduction, 

altered metabolism, reduced immune 

competence, and behavioral disturbance 

(e.g., Moberg 1987; Blecha 2000). 


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Increases in the circulation of 

glucocorticoids are also equated with 

stress (Romano et al., 2004). 

The primary distinction between 

stress (which is adaptive and does not 

normally place an animal at risk) and 

‘‘distress’’ is the cost of the response. 

During a stress response, an animal uses 

glycogen stores that can be quickly 

replenished once the stress is alleviated. 

In such circumstances, the cost of the 

stress response would not pose serious 

fitness consequences. However, when 

an animal does not have sufficient 

energy reserves to satisfy the energetic 

costs of a stress response, energy 

resources must be diverted from other 

functions. This state of distress will last 

until the animal replenishes its 

energetic reserves sufficient to restore 

normal function. 

Relationships between these 

physiological mechanisms, animal 

behavior, and the costs of stress 

responses are well-studied through 

controlled experiments and for both 

laboratory and free-ranging animals 

(e.g., Holberton et al., 1996; Hood et al., 

1998; Jessop et al., 2003; Krausman et 

al., 2004; Lankford et al., 2005). Stress 

responses due to exposure to 

anthropogenic sounds or other stressors 

and their effects on marine mammals 

have also been reviewed (Fair and 

Becker 2000; Romano et al., 2002b) and, 

more rarely, studied in wild populations 

(e.g., Romano et al., 2002a). For 

example, Rolland et al. (2012) found 

that noise reduction from reduced ship 

traffic in the Bay of Fundy was 

associated with decreased stress in 

North Atlantic right whales. These and 

other studies lead to a reasonable 

expectation that some marine mammals 

will experience physiological stress 

responses upon exposure to acoustic 

stressors and that it is possible that 

some of these would be classified as 

‘‘distress.’’ In addition, any animal 

experiencing TTS would likely also 

experience stress responses (NRC, 

2003), however distress is an unlikely 

result of this project based on 

observations of marine mammals during 

previous, similar projects in the area. 

Masking—Sound can disrupt behavior 

through masking, or interfering with, an 

animal’s ability to detect, recognize, or 

discriminate between acoustic signals of 

interest (e.g., those used for intraspecific 

communication and social interactions, 

prey detection, predator avoidance, 

navigation) (Richardson et al., 1995). 

Masking occurs when the receipt of a 

sound is interfered with by another 

coincident sound at similar frequencies 

and at similar or higher intensity, and 

may occur whether the sound is natural 

(e.g., snapping shrimp, wind, waves, 

precipitation) or anthropogenic (e.g., 

pile driving, shipping, sonar, seismic 

exploration) in origin. The ability of a 

noise source to mask biologically 

important sounds depends on the 

characteristics of both the noise source 

and the signal of interest (e.g., signal-tonoise ratio, temporal variability, 

direction), in relation to each other and 

to an animal’s hearing abilities (e.g., 

sensitivity, frequency range, critical 

ratios, frequency discrimination, 

directional discrimination, age or TTS 

hearing loss), and existing ambient 

noise and propagation conditions. 

Masking of natural sounds can result 

when human activities produce high 

levels of background sound at 

frequencies important to marine 

mammals. Conversely, if the 

background level of underwater sound 

is high (e.g., on a day with strong wind 

and high waves), an anthropogenic 

sound source would not be detectable as 

far away as would be possible under 

quieter conditions and would itself be 

masked. The San Diego area contains 

active military and commercial 

shipping, cruise ship and ferry 

operations, as well as numerous 

recreational and other commercial 

vessel and background sound levels in 

the area are already elevated as 

described in Dahl and Dall’Osta (2019). 

Potential Effects of High-Pressure 

Water Jetting, Underwater Chainsaw, 

and Pile Clipper Sounds—High-pressure 

water jetting, underwater chainsaws, 

and pile clippers may be used to assist 

with removal of piles (and water jetting 

may be used to aid installation). The 

sounds produced by these activities are 

of similar frequencies to the sounds 

produced by vessels (NAVFAC 

Southwest, 2020), and are anticipated to 

diminish to background noise levels (or 

be masked by background noise levels) 

in the Bay relatively close to the project 

site. Therefore, the effects of this 

equipment are likely to be similar to 

those discussed above in the Behavioral 

Harassment section. 

Airborne Acoustic Effects—Pinnipeds 

that occur near the project site could be 

exposed to airborne sounds associated 

with pile driving and removal that have 

the potential to cause behavioral 

harassment, depending on their distance 

from pile driving activities. Cetaceans 

are not expected to be exposed to 

airborne sounds that would result in 

harassment as defined under the 

MMPA. 

Airborne noise would primarily be an 

issue for pinnipeds that are swimming 

or hauled out near the project site 

within the range of noise levels elevated 

above the acoustic criteria. We 

recognize that pinnipeds in the water 

could be exposed to airborne sound that 

may result in behavioral harassment 

when looking with their heads above 

water. 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 the area 

and move further from the source. 

However, these animals would 

previously have been ‘taken’ because of 

exposure to underwater sound above the 

behavioral harassment thresholds, 

which are in all cases larger than those 

associated with airborne sound. Thus, 

the behavioral harassment of these 

animals is already accounted for in 

these estimates of potential take. 

Therefore, we do not believe that 

authorization of incidental take 

resulting from airborne sound for 

pinnipeds is warranted, and airborne 

sound is not discussed further here. 

Marine Mammal Habitat Effects 

The Navy’s construction activities 

could have localized, temporary impacts 

on marine mammal habitat and their 

prey by increasing in-water sound 

pressure levels and slightly decreasing 

water quality. Increased noise levels 

may affect acoustic habitat (see masking 

discussion above) and adversely affect 

marine mammal prey in the vicinity of 

the project area (see discussion below). 

During impact and vibratory pile 

driving or removal, elevated levels of 

underwater noise would ensonify San 

Diego Bay where both fishes and 

mammals occur and could affect 

foraging success. Additionally, marine 

mammals may avoid the area during 

construction, however, displacement 

due to noise is expected to be temporary 

and is not expected to result in longterm effects to the individuals or 

populations. Construction activities are 

of short duration and would likely have 

temporary impacts on marine mammal 

habitat through increases in underwater 

and airborne sound. 

A temporary and localized increase in 

turbidity near the seafloor would occur 

in the immediate area surrounding the 

area where piles are installed or 

removed. In general, turbidity 

associated with pile installation is 

localized to about a 25-foot (7.6-meter) 

radius around the pile (Everitt et al. 

1980). The sediments of the project site 

are sandy and will settle out rapidly 

when disturbed. Cetaceans are not 

expected to be close enough to the pile 

driving areas to experience effects of 

turbidity, and any pinnipeds could 


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avoid localized areas of turbidity. Local 

strong currents are anticipated to 

disburse any additional suspended 

sediments produced by project activities 

at moderate to rapid rates depending on 

tidal stage. Therefore, we expect the 

impact from increased turbidity levels 

to be discountable to marine mammals 

and do not discuss it further. 

In-Water Construction Effects on 

Potential Foraging Habitat 

The area likely impacted by the 

project is relatively small compared to 

the available habitat (e.g., the impacted 

area is in the south central bay only) of 

San Diego Bay and does not include any 

Biologically Important Areas or other 

habitat of known importance. The area 

is highly influenced by anthropogenic 

activities. The total seafloor area 

affected by pile installation and removal 

is a very small area compared to the vast 

foraging area available to marine 

mammals in the San Diego Bay. At best, 

the impact area provides marginal 

foraging habitat for marine mammals 

and fish. Furthermore, pile driving and 

removal at the project site would not 

obstruct movements or migration of 

marine mammals. 

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 nearby vicinity. 

In-water Construction Effects on 

Potential Prey—Sound may affect 

marine mammals through impacts on 

the abundance, behavior, or distribution 

of prey species (e.g., crustaceans, 

cephalopods, fish, zooplankton). Marine 

mammal prey varies by species, season, 

and location. Here, we describe studies 

regarding the effects of noise on known 

marine mammal prey. 

Fish utilize the soundscape and 

components of sound in their 

environment to perform important 

functions such as foraging, predator 

avoidance, mating, and spawning (e.g., 

Zelick and Mann, 1999; Fay, 2009). 

Depending on their hearing anatomy 

and peripheral sensory structures, 

which vary among species, fishes hear 

sounds using pressure and particle 

motion sensitivity capabilities and 

detect the motion of surrounding water 

(Fay et al., 2008). The potential effects 

of noise on fishes depends on the 

overlapping frequency range, distance 

from the sound source, water depth of 

exposure, and species-specific hearing 

sensitivity, anatomy, and physiology. 

Key impacts to fishes may include 

behavioral responses, hearing damage, 

barotrauma (pressure-related injuries), 

and mortality. 

Fish react to sounds which are 

especially strong and/or intermittent 

low-frequency sounds, and behavioral 

responses such as flight or avoidance 

are the most likely effects. Short 

duration, sharp sounds can cause overt 

or subtle changes in fish behavior and 

local distribution. The reaction of fish to 

noise depends on the physiological state 

of the fish, past exposures, motivation 

(e.g., feeding, spawning, migration), and 

other environmental factors. 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). 

Several studies have demonstrated that 

impulse sounds might affect the 

distribution and behavior of some 

fishes, potentially impacting foraging 

opportunities or increasing energetic 

costs (e.g., Fewtrell and McCauley, 

2012; Pearson et al., 1992; Skalski et al., 

1992; Santulli et al., 1999; Paxton et al., 

2017). However, some studies have 

shown no or slight reaction to impulse 

sounds (e.g., Pena et al., 2013; Wardle 

et al., 2001; Jorgenson and Gyselman, 

2009; Cott et al., 2012). 

SPLs of sufficient strength have been 

known to cause injury to fish and fish 

mortality. However, in most fish 

species, hair cells in the ear 

continuously regenerate and loss of 

auditory function likely is restored 

when damaged cells are replaced with 

new cells. Halvorsen et al. (2012a) 

showed that a TTS of 4–6 dB was 

recoverable within 24 hours for one 

species. Impacts would be most severe 

when the individual fish is close to the 

source and when the duration of 

exposure is long. Injury caused by 

barotrauma can range from slight to 

severe and can cause death, and is most 

likely for fish with swim bladders. 

Barotrauma injuries have been 

documented during controlled exposure 

to impact pile driving (Halvorsen et al., 

2012b; Casper et al., 2013). 

Because of the rarity of use and 

research, the effects of pile clippers, 

underwater chainsaws, and water jetting 

are not fully known; but given their 

similarity to ship noises we do not 

expect unique effects from these 

activities. 

The most likely impact to fish from 

pile driving and removal and 

demolition 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. 

Construction activities, in the form of 

increased turbidity, have the potential 

to adversely affect forage fish in the 

project area. Forage fish form a 

significant prey base for many marine 

mammal species that occur in the 

project area. Increased turbidity is 

expected to occur in the immediate 

vicinity (on the order of 10 feet (3 m) or 

less) of construction activities. However, 

suspended sediments and particulates 

are expected to dissipate quickly within 

a single tidal cycle. Given the limited 

area affected and high tidal dilution 

rates any effects on forage fish are 

expected to be minor or negligible. 

Finally, exposure to turbid waters from 

construction activities is not expected to 

be different from the current exposure; 

fish and marine mammals in San Diego 

Bay are routinely exposed to substantial 

levels of suspended sediment from 

natural and anthropogenic sources. 

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. Any behavioral avoidance by 

fish of the disturbed area would still 

leave significantly large areas of fish and 

marine mammal foraging habitat in the 

nearby vicinity. Thus, we conclude that 

impacts of the specified activity are not 

likely to have more than short-term 

adverse effects on any prey habitat or 

populations of prey species. Further, 

any impacts to marine mammal habitat 

are not expected to result in significant 

or long-term consequences for 

individual marine mammals, or to 

contribute to adverse impacts on their 

populations. 

Estimated Take 

This section provides an estimate of 

the number of incidental takes proposed 

for authorization through this IHA, 

which will inform both NMFS’ 

consideration of ‘‘small numbers’’ and 

the negligible impact determination. 

Harassment is the only type of take 

expected to result from these activities. 

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, 


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which (i) has the potential to injure a 

marine mammal or marine mammal 

stock in the wild (Level A harassment); 

or (ii) has the potential to disturb a 

marine mammal or marine mammal 

stock in the wild by causing disruption 

of behavioral patterns, including, but 

not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

(Level B harassment). 

Authorized takes would be by Level B 

harassment, as use of the acoustic 

source (i.e., vibratory or impact pile 

driving) has the potential to result in 

disruption of behavioral patterns for 

individual marine mammals. Based on 

the nature of the activity and the 

anticipated effectiveness of the 

mitigation measures (i.e., shutdown)— 

discussed in detail below in Proposed 

Mitigation section, Level A harassment 

is neither anticipated nor proposed to be 

authorized. 

As described previously, no mortality 

is anticipated or proposed to be 

authorized for this activity. Below we 

describe how the take is estimated. 

Generally speaking, we estimate take 

by considering: (1) Acoustic thresholds 

above which marine mammals will be 

behaviorally harassed or incur some 

degree of permanent hearing 

impairment; (2) the area or volume of 

water that will be ensonified above 

these levels in a day; (3) the density or 

occurrence of marine mammals within 

these ensonified areas; and, (4) and the 

number of days of activities. We note 

that while these basic factors can 

contribute to a basic calculation to 

provide an initial prediction of takes, 

additional information that can 

qualitatively inform take estimates is 

also sometimes available (e.g., previous 

monitoring results or average group 

size). Due to the lack of marine mammal 

density, NMFS relied on local 

occurrence data and group size to 

estimate take. Below, we describe the 

factors considered here in more detail 

and present the proposed take estimate. 

Acoustic Thresholds 

NMFS recommends the use of 

acoustic thresholds that identify the 

received level of underwater sound 

above which exposed marine mammals 

would be reasonably expected to be 

behaviorally harassed (equated to Level 

B harassment) or to incur PTS of some 

degree (equated to Level A harassment). 

Level B Harassment for non-explosive 

sources—Though significantly driven by 

received level, the onset of behavioral 

disturbance from anthropogenic noise 

exposure is also informed to varying 

degrees by other factors related to the 

source (e.g., frequency, predictability, 

duty cycle), the environment (e.g., 

bathymetry), and the receiving animals 

(hearing, motivation, experience, 

demography, behavioral context) and 

can be difficult to predict (Southall et 

al., 2007, Ellison et al., 2012). Based on 

what the available science indicates and 

the practical need to use a threshold 

based on a factor that is both predictable 

and measurable for most activities, 

NMFS uses a generalized acoustic 

threshold based on received level to 

estimate the onset of behavioral 

harassment. NMFS predicts that marine 

mammals are likely to be behaviorally 

harassed in a manner we consider Level 

B harassment when exposed to 

underwater anthropogenic noise above 

received levels of 120 dB re 1 

microPascal (mPa) (root mean square 

(rms)) for continuous (e.g., vibratory 

pile-driving) and above 160 dB re 1 mPa 

(rms) for non-explosive impulsive (e.g., 

impact pile driving) or intermittent (e.g., 

scientific sonar) sources. 

The Navy’s proposed activity includes 

the use of continuous (vibratory piledriving, water jetting, chainsaw and pile 

clippers) and impulsive (impact piledriving) sources, and therefore the 120 

and 160 dB re 1 mPa (rms) thresholds are 

applicable. However, as discussed 

above, the Navy has established that the 

ambient noise in the project area is 126 

dB re 1 mPa (rms). Since this is louder 

than the 120 dB threshold for 

continuous sources, 126 dB becomes the 

effective threshold for Level B 

harassment for continuous sources. 

Level A harassment for non-explosive 

sources—NMFS’ Technical Guidance 

for Assessing the Effects of 

Anthropogenic Sound on Marine 

Mammal Hearing (Version 2.0) 

(Technical Guidance, 2018) identifies 

dual criteria to assess auditory injury 

(Level A harassment) to five different 

marine mammal groups (based on 

hearing sensitivity) as a result of 

exposure to noise from two different 

types of sources (impulsive or nonimpulsive). The Navy’s activity includes 

the use of impulsive (impact piledriving) and non-impulsive (vibratory 

pile driving/removal and other removal 

methods) sources. 

These thresholds are provided in 

Table 4. The references, analysis, and 

methodology used in the development 

of the thresholds are described in NMFS 

2018 Technical Guidance, which may 

be accessed at https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/marinemammal-acoustic-technical-guidance. 

TABLE 4—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

Hearing group 

PTS onset acoustic thresholds * 

(Received level) 

Impulsive Non-impulsive 

Low-Frequency (LF) Cetaceans ...................................... Cell 1: Lpk,flat: 219 dB; LE,LF,24h: 183 dB ......................... Cell 2: LE,LF,24h: 199 dB. 

Mid-Frequency (MF) Cetaceans ...................................... Cell 3: Lpk,flat: 230 dB; LE,MF,24h: 185 dB ........................ Cell 4 LE,MF,24h: 198 dB. 

High-Frequency (HF) Cetaceans ..................................... Cell 5: Lpk,flat: 202 dB LE,HF,24h: 155 dB ......................... Cell 6 LE,HF,24h: 173 dB. 

Phocid Pinnipeds (PW) (Underwater) ............................. Cell 7: Lpk,flat: 218 dB LE,PW,24h: 185 dB ......................... Cell 8: LE,PW,24h: 201 dB. 

Otariid Pinnipeds (OW) (Underwater) ............................. Cell 9: Lpk,flat:232 dB LE,OW,24h: 203 dB .......................... Cell 10: LE,OW,24h: 219 dB. 

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should 

also be considered. 

Note: Peak sound pressure (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s. 

In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure 

is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ‘‘flat’’ is being 

included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated 

with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF 

cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level 

thresholds could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for 

action proponents to indicate the conditions under which these acoustic thresholds will be exceeded. 


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Ensonified Area 

Here, we describe operational and 

environmental parameters of the activity 

that will feed into identifying the area 

ensonified above the acoustic 

thresholds, which include source levels 

and transmission loss coefficient. 

The sound field in the project area is 

the existing background noise plus 

additional construction noise from the 

proposed project. Marine mammals are 

expected to be affected via sound 

generated by the primary components of 

the project (i.e., impact pile driving, 

vibratory pile removal, water jetting, 

pile clippers and underwater 

chainsaws). 

Vibratory hammers produce constant 

sound when operating, and produce 

vibrations that liquefy the sediment 

surrounding the pile, allowing it to 

penetrate to the required seating depth 

or be withdrawn more easily. An impact 

hammer is a steel device that works like 

a piston, producing a series of 

independent strikes to drive the pile. 

Impact hammering typically generates 

the loudest noise associated with pile 

installation. The actual durations of 

each installation method vary 

depending on the type and size of the 

pile. 

In order to calculate distances to the 

Level A harassment and Level B 

harassment sound thresholds for piles of 

various sizes being used in this project, 

NMFS used acoustic monitoring data 

from other locations to develop source 

levels for the various pile types, sizes 

and methods (see Table 5). Data for the 

removal methods including water 

jetting, pile clippers and underwater 

chainsaws come from data gathered at 

other nearby Navy projects in San Diego 

Bay (NAVFAC SW, 2020), the source 

levels used are from the averages of the 

maximum source levels measured, a 

somewhat more conservative measure 

than the median sound levels we 

typically use. 

TABLE 5—PROJECT SOUND SOURCE LEVELS

Pile driving activity Estimated sound source level at 10 meters without attenuation Data source and proxy 

Method Pile Type dB RMS dB SEL dB peak 

Vibratory Extraction ................... 12-inch timber/plastic ................ 152 .................... .................... Greenbusch Group (2018). 

20 and 24-inch concrete ........... 160 .................... .................... Caltrans (2015), Table I.2–2, 

24-inch steel sheet. 

16-inch steel ............................. 160 .................... .................... Caltrans (2015), Table I.2–2, 

24-inch steel sheet. 

Water Jetting ............................. 20-inch concrete ....................... 158 .................... .................... NAVFAC SW (2020), 24 x 30- 

inch concrete. 

Underwater Chainsaw ............... 12 to 24-inch concrete .............. 150 .................... .................... NAVFAC SW (2020), 16-inch 

concrete.* 

Small Pile Clipper ...................... 12-inch timber/plastic ................ 154 .................... .................... NAVFAC SW (2020), 13-inch 

polycarbonate. 

Large Pile Clipper ...................... 20-inch concrete ....................... 161 .................... .................... NAVFAC SW (2020), 24-inch 

concrete. 

Impact Hammer ......................... 20 and 24-inch concrete ........... 176 166 188 Caltrans (2015), Table I.2–1, 

24-inch concrete. 

16-inch fiberglass ..................... 153 ** 144 ** 177 Caltrans (2015), 13-inch plastic. 

Note: SEL = single strike sound exposure level; dB peak = peak sound level; rms = root mean square. 

* Source level was 147 dB at 17m from source, back calculated to 150dB using transmission loss coefficient of 15. 

** Average of the peak values was 166 and that value was used in modelling in Dell’Osto and Dahl (2019) rather than the absolute peak we 

recommend for use in the user spreadsheet, SEL calculated from assumed strike rate in Dell’Osto and Dahl (2019). 

During pile driving installation 

activities, there may be times when two 

pile extraction methods (pile clippers, 

water jetting, underwater chainsaws or 

vibratory pile removal) are used 

simultaneously. The likelihood of such 

an occurrence is anticipated to be 

infrequent, will depend on the specific 

methods chosen by the contractor, and 

would be for short durations on that 

day. In-water pile removal occurs 

intermittently, and it is common for 

removal to start and stop multiple times 

as each pile is adjusted and its progress 

is measured. Moreover, the Navy has 

multiple options for pile removal 

depending on the pile type and 

condition, sediment, and how stuck the 

pile is, etc. When two continuous noise 

sources, such as pile clippers, have 

overlapping sound fields, there is 

potential for higher sound levels than 

for non-overlapping sources. When two 

or more pile removal methods (pile 

clippers, water jetting, underwater 

chainsaws or vibratory pile removal) are 

used simultaneously, and the sound 

field of one source encompasses the 

sound field of another source, the 

sources are considered additive and 

combined using the following rules (see 

Table 6): For addition of two 

simultaneous methods, the difference 

between the two sound source levels 

(SSLs) is calculated, and if that 

difference is between 0 and 1 dB, 3 dB 

are added to the higher SSL; if 

difference is between 2 or 3 dB, 2 dB are 

added to the highest SSL; if the 

difference is between 4 to 9 dB, 1 dB is 

added to the highest SSL; and with 

differences of 10 or more dB, there is no 

addition (NMFS 2018b; WSDOT 2018). 

TABLE 6—RULES FOR COMBINING SOUND LEVELS GENERATED DURING PILE REMOVAL

Difference in SSL Level A zones Level B zones 

0 or 1 dB .............................. Add 3 dB to the higher source level ............................... Add 3 dB to the higher source level. 

2 or 3 dB .............................. Add 2 dB to the higher source level ............................... Add 2 dB to the higher source level. 

4 to 9 dB .............................. Add 1 dB to the higher source level ............................... Add 1 dB to the higher source level. 


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TABLE 6—RULES FOR COMBINING SOUND LEVELS GENERATED DURING PILE REMOVAL—Continued 

Difference in SSL Level A zones Level B zones 

10 dB or more ...................... Add 0 dB to the higher source level ............................... Add 0 dB to the higher source level. 

Source: Modified from USDOT 1995, WSDOT 2018, and NMFS 2018b 

Note: dB = decibels; SSL = sound source level. 

There is also the possibility that 

impact installation of piles could 

happen simultaneously with any of the 

non-impulsive removal methods over 

large portions of the project as described 

above. On days when this occurs the 

Level A harassment zones would be 

based on the zones calculated for impact 

pile driving while the Level B 

harassment zone would be the largest of 

the zones for whatever construction 

methods are being used that day. 

Level B Harassment Zones 

Transmission loss (TL) is the decrease 

in acoustic intensity as an acoustic 

pressure wave propagates out from a 

source. TL parameters vary with 

frequency, temperature, sea conditions, 

current, source and receiver depth, 

water depth, water chemistry, and 

bottom composition and topography. 

The general formula for underwater TL 

is: 

TL = B * Log10 (R1/R2), 

where 

TL = transmission loss in dB 

B = transmission loss coefficient; for practical 

spreading equals 15 

R1 = the distance of the modeled SPL from 

the driven pile, and 

R2 = the distance from the driven pile of the 

initial measurement 

The recommended TL coefficient for 

most nearshore environments is the 

practical spreading value of 15. This 

value results in an expected propagation 

environment that would lie between 

spherical and cylindrical spreading loss 

conditions, which is the most 

appropriate assumption for the Navy’s 

proposed activity in the absence of 

specific modelling. For this project 

however, the Navy did model sound 

propagation for the impact and vibratory 

hammering methods (Dall’Osto and 

Dahl 2019). For all other pile removal 

methods we used the practical 

spreading value. 

The Navy determined underwater 

noise would fall below the behavioral 

effects threshold of 126 dB rms for 

marine mammals at distances of less 

than 10 to 7,140 m depending on the 

pile type(s) and methods (Table 7). It 

should be noted that based on the 

bathymetry and geography of San Diego 

Bay, sound will not reach the full 

distance of the Level B harassment 

isopleths in all directions. Because the 

Navy’s as yet unhired contractor has not 

decided which of the various pile 

removal methods it will use, we only 

calculate a worst-case scenario of 

simultaneous operation of two of the 

loudest sound producing methods (large 

pile clippers) to consider the largest 

possible harassment zones for 

simultaneous pile removal. 

TABLE 7—LEVEL A AND LEVEL B ISOPLETHS FOR EACH PILE DRIVING TYPE AND METHOD

Pile Driving Activity Radial distance or maximum modeled length × width (m) 

Method Pile type Level A Level B 

Vibratory Extraction .................................................. 12-inch timber/plastic ............................................... <10 2167 × 1065. 

20 and 24-inch concrete .......................................... <10 6,990 × 1,173. 

16-inch steel ............................................................. <10 7,140 × 1,595. 

Water Jetting ............................................................. 20-inch concrete ...................................................... <10 1359. 

Underwater Chainsaw .............................................. 12 to 24-inch concrete ............................................. <10 398. 

Small Pile Clipper ..................................................... 12-inch timber/plastic ............................................... <10 736. 

Large Pile Clipper ..................................................... 20 to 24-inch concrete ............................................. <10 2154. 

Two Large Pile Clippers ........................................... 20 to 24-inch concrete ............................................. <10 3415. 

Impact Hammer ........................................................ 20 and 24-inch concrete .......................................... <10 192. 

16-inch fiberglass ..................................................... <10 <10. 

Level A Harassment Zones 

When the NMFS Technical Guidance 

(2016) was published, in recognition of 

the fact that ensonified area/volume 

could be more technically challenging 

to predict because of the duration 

component in the new thresholds, we 

developed a User Spreadsheet that 

includes tools to help predict a simple 

isopleth that can be used in conjunction 

with marine mammal density or 

occurrence to help predict takes. We 

note that because of some of the 

assumptions included in the methods 

used for these tools, we anticipate that 

isopleths produced are typically going 

to be overestimates of some degree, 

which may result in some degree of 

overestimate of take by Level A 

harassment. However, these tools offer 

the best way to predict appropriate 

isopleths when more sophisticated 3D 

modeling methods are not available, and 

NMFS continues to develop ways to 

quantitatively refine these tools, and 

will qualitatively address the output 

where appropriate. For stationary 

sources such as impact/vibratory pile 

driving or removal using any of the 

methods discussed above, NMFS User 

Spreadsheet predicts the closest 

distance at which, if a marine mammal 

remained at that distance the whole 

duration of the activity, it would not 

incur PTS. 

As discussed above, the Navy 

modelled sound propagation for impact 

and vibratory hammering of piles 

(Dall’Osto and Dahl 2019) and used 

those models to calculate Level A 

harassment isopleths. For all other pile 

removal methods we used the User 

Spreadsheet to determine the Level A 

harassment isopleths. Inputs used in the 

User Spreadsheet or models are reported 

in Table 8 and the resulting isopleths 

are reported in Table 7 for each of 

construction methods. 


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TABLE 8—NMFS TECHNICAL GUIDANCE USER SPREADSHEET INPUT TO CALCULATE LEVEL A ISOPLETHS FOR A

COMBINATION OF PILE DRIVING

Pile Driving Activity Radial distance or maximum modeled length × width (m) 

Method Pile Type Piles per day 

Strikes per pile/ 

duration to drive 

a single pile 

Vibratory Extraction .................................................. 12-inch timber/plastic ............................................... 8 10 minutes. 

20 and 24-inch concrete .......................................... 8 10 minutes. 

16-inch steel ............................................................. 8 10 minutes. 

Water Jetting ............................................................. 20-inch concrete ...................................................... 8 20 minutes. 

Underwater Chainsaw .............................................. 12 to 24-inch concrete ............................................. 8 10 minutes. 

Small Pile Clipper ..................................................... 12-inch timber/plastic ............................................... 8 10 minutes. 

Large Pile Clipper ..................................................... 20-inch concrete ...................................................... 8 10 minutes. 

Impact Hammer ........................................................ 20 and 24-inch concrete .......................................... 7 600 strikes. 

16-inch fiberglass ..................................................... 7 600 strikes. 

The above input scenarios lead to PTS 

isopleth distances (Level A thresholds) 

of less than 10 m for all methods and 

piles (Table 7). 

Marine Mammal Occurrence and Take 

Calculation and Estimation 

In this section we provide the 

information about the presence, density, 

or group dynamics of marine mammals 

that will inform the take calculations. 

Here we describe how the information 

provided above is brought together to 

produce a quantitative take estimate. 

No California sea lion density 

information is available for south San 

Diego Bay. Potential exposures to 

impact and vibratory pile driving noise 

for each threshold for California sea 

lions were estimated using data 

collected during a 2010 survey as 

reported in Sorensen and Swope (2010). 

During this survey two separate sea 

lions were observed in the project area. 

The available survey data from 

Sorenson and Swope (2010) and other 

unpublished monitoring data from 

recent nearby projects on Naval Base 

San Diego suggests two California sea 

lions could be present each day in the 

project area. However given the limited 

data available and the more northerly 

location of this project relative to the 

recent dry dock project (https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-us-navyfloating-dry-dock-project-naval-basesan-diego) where we estimate two 

California sea lions per day, to be 

conservative, we have estimated four 

California sea lions could be present 

each day. As noted above, there are 250 

days of in-water work for this project. 

Multiplication of the above estimate of 

animals per day (4) times the days of 

work (250) results in a proposed Level 

B harassment take of 1000 California sea 

lions (Table 9). The Navy intends to 

avoid Level A harassment take by 

shutting down activities if a California 

sea lion approaches within 20 m of the 

project site, which encompasses all 

Level A harassment ensonification 

zones. Therefore, no take by Level A 

harassment is anticipated or proposed 

for authorization. 

TABLE 9—PROPOSED AUTHORIZED AMOUNT OF TAKING, BY LEVEL A HARASSMENT AND LEVEL B HARASSMENT, BY

SPECIES AND STOCK AND PERCENT OF TAKE BY STOCK

Species 

Authorized Take 

Percent of Stock 

Level B Level A 

California sea lion (Zalophus californianus) U.S. Stock .................................................. 1000 0 0.4 

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 the activity, and 

other means of effecting the least 

practicable impact on the species or 

stock and its habitat, paying particular 

attention to rookeries, mating grounds, 

and areas of similar significance, and on 

the availability of the species or stock 

for taking for certain subsistence uses 

(latter not applicable for this action). 

NMFS regulations require applicants for 

incidental take authorizations to include 

information about the availability and 

feasibility (economic and technological) 

of equipment, methods, and manner of 

conducting the activity or other means 

of effecting the least practicable adverse 

impact upon the affected species or 

stocks and their habitat (50 CFR 

216.104(a)(11)). 

In evaluating how mitigation may or 

may not be appropriate to ensure the 

least practicable adverse impact on 

species or stocks and their habitat, as 

well as subsistence uses where 

applicable, we carefully consider two 

primary factors: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure(s) is 

expected to reduce impacts to marine 

mammals, marine mammal species or 

stocks, and their habitat. This considers 

the nature of the potential adverse 

impact being mitigated (likelihood, 

scope, range). It further considers the 

likelihood that the measure will be 

effective if implemented (probability of 

accomplishing the mitigating result if 

implemented as planned), the 

likelihood of effective implementation 

(probability implemented as planned); 

and 

(2) The practicability of the measures 

for applicant implementation, which 

may consider such things as cost, 

impact on operations, and, in the case 

of a military readiness activity, 

personnel safety, practicality of 

implementation, and impact on the 

effectiveness of the military readiness 

activity. 

The following mitigation measures are 

proposed in the IHA: 

• For in-water heavy machinery work 

other than pile driving, if a marine 


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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; or (2) positioning of the pile on 

the substrate via a crane (i.e., stabbing 

the pile); 

• Conduct briefings between 

construction supervisors and crews and 

the marine mammal monitoring team 

prior to the start of all pile driving 

activity and when new personnel join 

the work, to explain responsibilities, 

communication procedures, marine 

mammal monitoring protocol, and 

operational procedures; 

• For those marine mammals for 

which Level B harassment take has not 

been requested, in-water pile 

installation/removal will shut down 

immediately if such species are 

observed within or entering the Level B 

harassment zone; and 

• If take reaches the authorized limit 

for an authorized species, pile 

installation will be stopped as these 

species approach the Level B 

harassment zone to avoid additional 

take. 

The following mitigation measures 

would apply to the Navy’s in-water 

construction activities. 

• Establishment of Shutdown 

Zones—The Navy will establish 

shutdown zones for all pile driving and 

removal activities. The purpose of a 

shutdown zone is generally to define an 

area within which shutdown of the 

activity would occur upon sighting of a 

marine mammal (or in anticipation of an 

animal entering the defined area). 

Shutdown zones typically vary based on 

the activity type and marine mammal 

hearing group (Table 4). In this case 

there is only one species affected and all 

level A harassment isopleths are less 

than 10 m radius. To be conservative, 

the Navy will establish a 20 m 

shutdown zone for all pile driving or 

removal activities. 

• The placement of Protected Species 

Observers (PSOs) during all pile driving 

and removal activities (described in 

detail in the Proposed Monitoring and 

Reporting section) will ensure that the 

entire shutdown zone is visible during 

pile installation. Should environmental 

conditions deteriorate such that marine 

mammals within the entire shutdown 

zone would not be visible (e.g., fog, 

heavy rain), pile driving and removal 

must be delayed until the PSO is 

confident marine mammals within the 

shutdown zone could be detected. 

• Monitoring for Level B 

Harassment—The Navy will monitor 

the Level A and B harassment zones. 

Monitoring zones provide utility for 

observing by establishing monitoring 

protocols for areas adjacent to the 

shutdown zones. Monitoring zones 

enable observers to be aware of and 

communicate the presence of marine 

mammals in the project area outside the 

shutdown zone and thus prepare for a 

potential halt of activity should the 

animal enter the shutdown zone. 

Placement of PSOs will allow PSOs to 

observe marine mammals within the 

Level B harassment zones. 

• Pre-activity Monitoring—Prior to 

the start of daily in-water construction 

activity, or whenever a break in pile 

driving/removal of 30 minutes or longer 

occurs, PSOs will observe the shutdown 

and monitoring zones for a period of 30 

minutes. The shutdown zone will be 

considered cleared when a marine 

mammal has not been observed within 

the zone for that 30-minute period. If a 

marine mammal is observed within the 

shutdown zone, a soft-start cannot 

proceed until the animal has left the 

zone or has not been observed for 15 

minutes. When a marine mammal for 

which Level B harassment take is 

authorized is present in the Level B 

harassment zone, activities may begin 

and Level B harassment take will be 

recorded. If the entire Level B 

harassment zone is not visible at the 

start of construction, pile driving 

activities can begin. If work ceases for 

more than 30 minutes, the pre-activity 

monitoring of the shutdown zones will 

commence. 

• Soft Start—Soft-start procedures are 

believed to provide additional 

protection to marine mammals by 

providing warning and/or giving marine 

mammals a chance to leave the area 

prior to the impact hammer operating at 

full capacity. For impact pile driving, 

contractors will be required to provide 

an initial set of three strikes from the 

hammer at reduced energy, followed by 

a 30-second waiting period. This 

procedure will be conducted three times 

before impact pile driving begins. Soft 

start will be implemented at the start of 

each day’s impact pile driving and at 

any time following cessation of impact 

pile driving for a period of 30 minutes 

or longer. 

Based on our evaluation of the 

applicant’s proposed measures, as well 

as other measures considered by NMFS, 

NMFS has preliminarily determined 

that the proposed mitigation measures 

provide the means effecting the least 

practicable impact on the affected 

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 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. 

Effective reporting is critical both to 

compliance as well as ensuring that the 

most value is obtained from the required 

monitoring. 

Monitoring and reporting 

requirements prescribed by NMFS 

should contribute to improved 

understanding of one or more of the 

following: 

• Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density); 

• Nature, scope, or context of likely 

marine mammal exposure to potential 

stressors/impacts (individual or 

cumulative, acute or chronic), through 

better understanding of: (1) Action or 

environment (e.g., source 

characterization, propagation, ambient 

noise); (2) affected species (e.g., life 

history, dive patterns); (3) co-occurrence 

of marine mammal species with the 

action; or (4) biological or behavioral 

context of exposure (e.g., age, calving or 

feeding areas); 

• Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors; 

• How anticipated responses to 

stressors impact either: (1) Long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks; 

• Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat); and 

• Mitigation and monitoring 

effectiveness. 

Visual Monitoring 

Marine mammal monitoring must be 

conducted in accordance with the 

Monitoring Plan and Section 5 of the 

IHA. Marine mammal monitoring 

during pile driving and removal must be 

conducted by NMFS-approved PSOs in 

a manner consistent with the following: 


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• Independent PSOs (i.e., not 

construction personnel) who have no 

other assigned tasks during monitoring 

periods must be used; 

• At least one PSO must have prior 

experience performing the duties of a 

PSO during construction activity 

pursuant to a NMFS-issued incidental 

take authorization. 

• Other PSOs may substitute 

education (degree in biological science 

or related field) or training for 

experience; 

• Where a team of three or more PSOs 

are required, a lead observer or 

monitoring coordinator must be 

designated. The lead observer must have 

prior experience performing the duties 

of a PSO during construction activity 

pursuant to a NMFS-issued incidental 

take authorization; and 

• The Navy must submit PSO 

Curriculum Vitae for approval by NMFS 

prior to the onset of pile driving. 

PSOs must have the following 

additional qualifications: 

• Ability to conduct field 

observations and collect data according 

to assigned protocols; 

• 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, times, 

and reason for implementation of 

mitigation (or why mitigation was not 

implemented when required); 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. 

Up to four PSOs will be employed. 

PSO locations will provide an 

unobstructed view of all water within 

the shutdown zone, and as much of the 

Level A and Level B harassment zones 

as possible. PSO locations are as 

follows: 

(1) At the pile driving/removal site or 

best vantage point practicable to 

monitor the shutdown zones; 

(2) For activities with Level B 

harassment zones larger than 400 m two 

additional PSO locations will be used. 

One will be across from the project 

location along Inchon Road at Naval 

Amphibious Base Coronado; and 

(3) Two additional PSOs will be 

located in a small boat. The boat will 

conduct a pre-activity survey of the 

entire monitoring area prior to in-water 

construction. The boat will start from 

south of the project area (where 

potential marine mammal occurrence is 

lowest) and proceed to the north. When 

the boat arrives near the northern 

boundary of the Level B harassment 

zone (e.g., just north of the western side 

of the Coronado Bridge as depicted in 

the Figures in the monitoring plan) it 

will set up station so the PSOs are best 

situated to detect any marine mammals 

that may approach from the north. The 

two PSOs aboard will split monitoring 

duties in order to monitor a 360 degree 

sweep around the vessel with each PSO 

responsible for 180 degrees of 

observable area. 

Monitoring will be conducted 30 

minutes before, during, and 30 minutes 

after pile driving/removal 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 or 

removed. Pile driving activities include 

the time to install or remove a single 

pile or series of piles, as long as the time 

elapsed between uses of the pile driving 

or drilling equipment is no more than 

30 minutes. 

Hydroacoustic Monitoring and 

Reporting 

The Navy has volunteered to conduct 

hydroacoustic monitoring of all pile 

driving and removal methods. Data will 

be collected for a representative number 

of piles (three to five) for each 

installation or removal method. As part 

of the below-mentioned report, or in a 

separate report with the same timelines 

as above, the Navy will provide an 

acoustic monitoring report for this work. 

Hydroacoustic monitoring results can be 

used to adjust the size of the Level B 

harassment and monitoring zones after 

a request is made and approved by 

NMFS. The acoustic monitoring report 

must, at minimum, include the 

following: 

• Hydrophone equipment and 

methods: recording device, sampling 

rate, distance (m) from the pile where 

recordings were made; depth of 

recording device(s). 

• Type of pile being driven or 

removed, substrate type, method of 

driving or removal during recordings. 

• For impact pile driving: Pulse 

duration and mean, median, and 

maximum sound levels (dB re: 1mPa): 

SELcum, peak sound pressure level 

(SPLpeak), and single-strike sound 

exposure level (SELs-s). 

• For vibratory removal and other 

non-impulsive sources: Mean, median, 

and maximum sound levels (dB re: 

1mPa): root mean square sound pressure 

level (SPLrms), SELcum. 

• Number of strikes (impact) or 

duration (vibratory or other nonimpulsive sources) per pile measured, 

one-third octave band spectrum and 

power spectral density plot. 

Reporting 

A draft marine mammal monitoring 

report will be submitted to NMFS 

within 90 days after the completion of 

pile driving and removal activities, or 

60 days prior to a requested date of 

issuance of any future IHAs for projects 

at the same location, whichever comes 

first. The report will include an overall 

description of work completed, a 

narrative regarding marine mammal 

sightings, and associated PSO data 

sheets. Specifically, the report must 

include: 

• Dates and times (begin and end) of 

all marine mammal monitoring; 

• Construction activities occurring 

during each daily observation period, 

including how many and what type of 

piles were driven or removed and by 

what method (i.e., impact or vibratory 

and if other removal methods were 

used); 

• Weather parameters and water 

conditions during each monitoring 

period (e.g., wind speed, percent cover, 

visibility, sea state); 

• The number of marine mammals 

observed, by species, relative to the pile 

location and if pile driving or removal 

was occurring at time of sighting; 

• Age and sex class, if possible, of all 

marine mammals observed; 

• PSO locations during marine 

mammal monitoring; 

• Distances and bearings of each 

marine mammal observed to the pile 

being driven or removed for each 

sighting (if pile driving or removal was 

occurring at time of sighting); 

• Description of any marine mammal 

behavior patterns during observation, 

including direction of travel and 

estimated time spent within the Level A 

and Level B harassment zones while the 

source was active; 

• Number of individuals of each 

species (differentiated by month as 

appropriate) detected within the 

monitoring zone; 

• Detailed information about any 

implementation of any mitigation 

triggered (e.g., shutdowns and delays), a 

description of specific actions that 

ensued, and resulting behavior of the 

animal, if any; and 


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• Description of attempts to 

distinguish between the number of 

individual animals taken and the 

number of incidences of take, such as 

ability to track groups or individuals. 

If no comments are received from 

NMFS within 30 days, the draft final 

report will constitute the final report. If 

comments are received, a final report 

addressing NMFS comments must be 

submitted within 30 days after receipt of 

comments. 

Reporting Injured or Dead Marine 

Mammals 

In the event that personnel involved 

in the construction activities discover 

an injured or dead marine mammal, the 

Navy shall report the incident to the 

Office of Protected Resources (OPR), 

NMFS and to the regional stranding 

coordinator as soon as feasible. If the 

death or injury was clearly caused by 

the specified activity, the Navy must 

immediately cease the specified 

activities until NMFS is able to review 

the circumstances of the incident and 

determine what, if any, additional 

measures are appropriate to ensure 

compliance with the terms of the IHA. 

The IHA-holder must not resume their 

activities until notified by NMFS. The 

report must include the following 

information: 

• Time, date, and location (latitude/ 

longitude) of the first discovery (and 

updated location information if known 

and applicable); 

• Species identification (if known) or 

description of the animal(s) involved; 

• Condition of the animal(s) 

(including carcass condition if the 

animal is dead); 

• Observed behaviors of the 

animal(s), if alive; 

• If available, photographs or video 

footage of the animal(s); and 

• General circumstances under which 

the animal was discovered. 

Negligible Impact Analysis and 

Determination 

NMFS has defined negligible impact 

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 

(50 CFR 216.103). A negligible impact 

finding is based on the lack of likely 

adverse effects on annual rates of 

recruitment or survival (i.e., populationlevel effects). An estimate of the number 

of takes alone is not enough information 

on which to base an impact 

determination. In addition to 

considering estimates of the number of 

marine mammals that might be ‘‘taken’’ 

through harassment, NMFS considers 

other factors, such as the likely nature 

of any responses (e.g., intensity, 

duration), the context of any responses 

(e.g., critical reproductive time or 

location, migration), as well as effects 

on habitat, and the likely effectiveness 

of the mitigation. We also assess the 

number, intensity, and context of 

estimated takes by evaluating this 

information relative to population 

status. Consistent with the 1989 

preamble for NMFS’s implementing 

regulations (54 FR 40338; September 29, 

1989), the impacts from other past and 

ongoing anthropogenic activities are 

incorporated into this analysis via their 

impacts on the environmental baseline 

(e.g., as reflected in the regulatory status 

of the species, population size and 

growth rate where known, ongoing 

sources of human-caused mortality, or 

ambient noise levels). 

Pile driving activities have the 

potential to disturb or displace marine 

mammals. Specifically, the project 

activities may result in take, in the form 

of Level B harassment from underwater 

sounds generated from pile driving and 

removal. Potential takes could occur if 

individuals are present in the ensonified 

zone when these activities are 

underway. 

The takes from Level B harassment 

would be due to potential behavioral 

disturbance, TTS, and PTS. No 

mortality is anticipated given the nature 

of the activity and measures designed to 

minimize the possibility of injury to 

marine mammals. The potential for 

harassment is minimized through the 

construction method and the 

implementation of the planned 

mitigation measures (see Proposed 

Mitigation section). 

The nature of the pile driving project 

precludes the likelihood of serious 

injury or mortality. Take would occur 

within a limited, confined area (southcentral San Diego Bay) of the stock’s 

range. Level B harassment will be 

reduced to the level of least practicable 

adverse impact through use of 

mitigation measures described herein. 

Further the amount of take proposed to 

be authorized is extremely small when 

compared to stock abundance. 

Behavioral responses of marine 

mammals to pile driving at the project 

site, if any, are expected to be mild and 

temporary. Marine mammals within the 

Level B harassment zone may not show 

any visual cues they are disturbed by 

activities (as noted during modification 

to the Kodiak Ferry Dock) or could 

become alert, avoid the area, leave the 

area, or display other mild responses 

that are not observable such as changes 

in vocalization patterns. Given the short 

duration of noise-generating activities 

per day and that pile driving and 

removal would occur across six months, 

any harassment would be temporary. 

There are no other areas or times of 

known biological importance for any of 

the affected species. 

In addition, it is unlikely that minor 

noise effects in a small, localized area of 

habitat would have any effect on the 

stocks’ ability to recover. In 

combination, we believe that these 

factors, as well as the available body of 

evidence from other similar activities, 

demonstrate that the potential effects of 

the specified activities will have only 

minor, short-term effects on individuals. 

The specified activities are not expected 

to impact rates of recruitment or 

survival and will therefore not result in 

population-level impacts. 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from this activity are 

not expected to adversely affect the 

species or stock through effects on 

annual rates of recruitment or survival: 

• No mortality or Level A harassment 

is anticipated or authorized; 

• No important habitat areas have 

been identified within the project area; 

• For all species, San Diego Bay is a 

very small and peripheral part of their 

range; 

• The Navy would implement 

mitigation measures such as vibratory 

driving piles to the maximum extent 

practicable, soft-starts, and shut downs; 

and 

• Monitoring reports from similar 

work in San Diego Bay have 

documented little to no effect on 

individuals of the same species 

impacted by the specified activities. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

proposed monitoring and mitigation 

measures, NMFS preliminarily finds 

that the total marine mammal take from 

the proposed activity will have a 

negligible impact on all affected marine 

mammal species or stocks. 

Small Numbers 

As noted above, only small numbers 

of incidental take may be authorized 

under section 101(a)(5)(D) of the MMPA 

for specified activities other than 

military readiness activities. The MMPA 

does not define small numbers and so, 

in practice, where estimated numbers 

are available, NMFS compares the 

number of individuals taken to the most 

appropriate estimation of abundance of 

the relevant species or stock in our 


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determination of whether an 

authorization is limited to small 

numbers of marine mammals. When the 

predicted number of individuals to be 

taken is fewer than one third of the 

species or stock abundance, the take is 

considered to be of small numbers. 

Additionally, other qualitative factors 

may be considered in the analysis, such 

as the temporal or spatial scale of the 

activities. 

The amount of take NMFS proposes to 

authorize is below one third of the 

estimated stock abundance of California 

sea lions (in fact, take of individuals is 

less than 1% of the abundance of the 

affected stock). This is likely a 

conservative estimate because they 

assume all takes are of different 

individual animals which is likely not 

the case. Some individuals may return 

multiple times in a day, but PSOs would 

count them as separate takes if they 

cannot be individually identified. 

Based on the analysis contained 

herein of the proposed activity 

(including the proposed mitigation and 

monitoring measures) and the 

anticipated take of marine mammals, 

NMFS preliminarily finds that small 

numbers of marine mammals will be 

taken relative to the population size of 

the affected species or stocks. 

Unmitigable Adverse Impact Analysis 

and Determination 

There are no relevant subsistence uses 

of the affected marine mammal stocks or 

species implicated by this action. 

Therefore, NMFS has determined that 

the total taking of affected species or 

stocks would not have an unmitigable 

adverse impact on the availability of 

such species or stocks for taking for 

subsistence purposes. 

Endangered Species Act 

Section 7(a)(2) of the ESA (16 U.S.C. 

1531 et seq.) requires that each Federal 

agency insure that any action it 

authorizes, funds, or carries out is not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or result in the 

destruction or adverse modification of 

designated critical habitat. To ensure 

ESA compliance for the issuance of 

IHAs, NMFS consults internally, in this 

case with the West Coast Region 

Protected Resources Division Office, 

whenever we propose to authorize take 

for endangered or threatened species. 

No incidental take of ESA-listed 

species is proposed for authorization or 

expected to result from this activity. 

Therefore, NMFS has determined that 

formal consultation under section 7 of 

the ESA is not required for this action. 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to issue 

an IHA to the Navy to conduct the Naval 

Base San Diego Pier 6 Replacement 

project in San Diego, CA from October 

1, 2021 through September 30, 2022, 

provided the previously mentioned 

mitigation, monitoring, and reporting 

requirements are incorporated. A draft 

of the proposed IHA can be found at 

https://www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-undermarine-mammal-protection-act. 

Request for Public Comments 

We request comment on our analyses, 

the proposed authorization, and any 

other aspect of this notice of proposed 

IHA for the proposed Naval Base San 

Diego Pier 6 Replacement project. We 

also request at this time comment on the 

potential renewal of this proposed IHA 

as described in the paragraph below. 

Please include with your comments any 

supporting data or literature citations to 

help inform decisions on the request for 

this IHA or a subsequent Renewal IHA. 

On a case-by-case basis, NMFS may 

issue a one-time one-year Renewal IHA 

following notice to the public providing 

an additional 15 days for public 

comments when (1) up to another year 

of identical, or nearly identical, 

activities as described in the Description 

of Proposed Activity section of this 

notice is planned or (2) the activities as 

described in the Description of 

Proposed Activity section of this notice 

would not be completed by the time the 

IHA expires and a Renewal would allow 

for completion of the activities beyond 

that described in the Dates and Duration 

section of this notice, provided all of the 

following conditions are met: 

• A request for renewal is received no 

later than 60 days prior to the needed 

Renewal IHA effective date (recognizing 

that Renewal IHA expiration date 

cannot extend beyond one year from 

expiration of the initial IHA); 

• The request for renewal must 

include the following: 

(1) An explanation that the activities 

to be conducted under the requested 

Renewal IHA are identical to the 

activities analyzed under the initial 

IHA, are a subset of the activities, or 

include changes so minor (e.g., 

reduction in pile size) that the changes 

do not affect the previous analyses, 

mitigation and monitoring 

requirements, or take estimates (with 

the exception of reducing the type or 

amount of take); and 

(2) A preliminary monitoring report 

showing the results of the required 

monitoring to date and an explanation 

showing that the monitoring results do 

not indicate impacts of a scale or nature 

not previously analyzed or authorized; 

and 

• Upon review of the request for 

Renewal, the status of the affected 

species or stocks, and any other 

pertinent information, NMFS 

determines that there are no more than 

minor changes in the activities, the 

mitigation and monitoring measures 

will remain the same and appropriate, 

and the findings in the initial IHA 

remain valid. 

Dated: December 7, 2020. 

Donna S. Wieting, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2020–27225 Filed 12–10–20; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648- XA677] 

Takes of Marine Mammals Incidental 

To Specified Activities; Taking Marine 

Mammals Incidental to the U.S. Coast 

Guard’s Base Los Angeles/Long Beach 

Wharf Expansion Project, Los Angeles, 

California 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; issuance of an incidental 

harassment authorization. 

SUMMARY: In accordance with the 

regulations implementing the Marine 

Mammal Protection Act (MMPA) as 

amended, notification is hereby given 

that NMFS has issued an incidental 

harassment authorization (IHA) to the 

U. S. Coast Guard (Coast Guard) to 

incidentally harass, by Level B 

harassment only, marine mammals 

during activities associated with the 

Base Los Angeles/Long Beach Wharf 

Expansion Project in Los Angeles, 

California. 

DATES: This Authorization is effective 

from February 1, 2021 through January 

31, 2022. 

FOR FURTHER INFORMATION CONTACT: 

Dwayne Meadows, Ph.D., Office of 

Protected Resources, NMFS, (301) 427– 

8401. Electronic copies of the 

application and supporting documents, 

as well as a list of the references cited 

in this document, may be obtained 

online at: https://

www.fisheries.noaa.gov/permit/ 

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