82836 Federal Register / Vol. 88, No. 226 / Monday, November 27, 2023 / Notices 

December 1, 2023 by the ORAP DFO 

(DFO.orap@noaa.gov) to provide 

sufficient time for ORAP review. 

Written comments received by the 

ORAP DFO after this date will be 

distributed to the ORAP, but may not be 

reviewed prior to the meeting date. 

Special Accommodations: These 

meetings are physically accessible to 

people with disabilities. Requests for 

special accommodations may be 

directed to the ORAP DFO no later than 

12 p.m. EST on December 1, 2023. 

Matters To Be Considered: The 

December 13–14, 2023 meeting, will 

explore the Ocean Policy Committee 

(OPC) Action Plan and identify areas for 

ORAP focus. Additionally, as the first 

meeting of ORAP advising OPC, it will 

allow ORAP to organize internally to 

conduct work. The expected outcomes 

are a shared understanding between 

ORAP and OPC on interests, capacities, 

opportunities, and expectations 

regarding ORAP efforts, and 

identification of initial topics for ORAP 

to address. 

Meeting materials, including work 

products, will be made available on the 

ORAP website: https://www.noaa.gov/ 

ocean-research-advisory-panel/orappublic-meetings. 

Dated: November 14, 2023. 

David Holst, 

Director Chief Financial Officer/CAO, Office 

of Oceanic and Atmospheric Research, 

National Oceanic and Atmospheric 

Administration. 

[FR Doc. 2023–26076 Filed 11–24–23; 8:45 am] 

BILLING CODE 3510–KD–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD458] 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to Pacific Gas & 

Electric Sediment Remediation Project, 

San Francisco Bay 

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 Pacific Gas & Electric Company 

(PG&E) for authorization to take marine 

mammals incidental to construction 

associated with a sediment remediation 

project in San Francisco Bay, 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-time, oneyear 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 authorization and 

agency responses will be summarized in 

the final notice of our decision. 

DATES: Comments and information must 

be received no later than December 27, 

2023. 

ADDRESSES: Comments should be 

addressed to Jolie Harrison, Chief, 

Permits and Conservation Division, 

Office of Protected Resources, National 

Marine Fisheries Service and should be 

submitted via email to ITP.jacobus@

noaa.gov. 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/national/ 

marine-mammal-protection/incidentaltake-authorizations-constructionactivities. In case of problems accessing 

these documents, please call the contact 

listed above. 

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, including all 

attachments, must not exceed a 25- 

megabyte file size. All comments 

received are a part of the public record 

and will generally be posted online at 

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

national/marine-mammal-protection/ 

incidental-take-authorizationsconstruction-activities 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. 

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/ 

national/marine-mammal-protection/ 

incidental-take-authorizationsconstruction-activities. In case of 

problems accessing these documents, 

please call the contact listed below. 

FOR FURTHER INFORMATION CONTACT: 

Kristy Jacobus, Office of Protected 

Resources, NMFS, (301) 427–8401. 

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 

proposed or, if the taking is limited to 

harassment, a notice of a proposed IHA 

is provided to the public for review. 

Authorization for incidental takings 

shall be granted if NMFS finds that the 

taking will have a negligible impact on 

the species or stock(s) 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 


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Federal Register / Vol. 88, No. 226 / Monday, November 27, 2023 / Notices 82837 

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 May 4, 2023, NMFS received a 

request from PG&E for an IHA to take 

marine mammals incidental to a 

Sediment Remediation Project in 

Remedial Response Areas A and B, Piers 

39 to 431⁄2, San Francisco Bay. 

Following NMFS’ review of the 

application, PG&E submitted additional 

information on July 25, 2023 and 

September 26, 2023 and subsequently 

submitted a revised application on 

November 16, 2023, which was deemed 

adequate and complete. PG&E’s request 

is for take of seven species (eight stocks) 

of marine mammals by Level B 

harassment only. Neither PG&E nor 

NMFS expect serious injury or mortality 

to result from this activity and, 

therefore, an IHA is appropriate. 

This proposed IHA would cover 1 

year of a larger project for which PG&E 

intends to request take authorization for 

subsequent facets of the project if 

necessary. The larger 5–7 year project 

involves construction to remediate 

contaminated sediment. 

Description of Proposed Activity 

Overview 

PG&E is proposing to remediate 

sediments impacted with polycyclic 

aromatic hydrocarbons (PAHs) in San 

Francisco Bay around the area offshore 

of Pier 431⁄2 to the east of Pier 45 and 

offshore area of Pier 43. As part of the 

proposed project, PG&E is proposing to 

use primarily vibratory pile driving to 

install steel piles for a turbidity curtain 

and temporary relocation of the Red and 

White Fleet (RWF) and wood or 

composite piles for slope stabilization. 

Impact pile driving would only be used 

as needed to seat these piles. In 

addition, PG&E plans to use impact pile 

driving to install composite plastic piles 

as part of a hydroacoustic data 

collection. Vibratory and impact pile 

driving would introduce underwater 

sounds that may result in take, by Level 

B harassment, of marine mammals. This 

proposed IHA would authorize take for 

Year 1 of the project, which is 

scheduled to begin in spring of 2024. 

PG&E’s proposed activity includes 

impact and vibratory pile driving and 

vibratory pile removal, which may 

result in the incidental take of marine 

mammals, by harassment only. No Level 

A harassment is anticipated to occur, 

and none is proposed for authorization. 

Dates and Duration 

The proposed IHA would be effective 

from May 1, 2024 to April 30, 2025. Up 

to 50 days of pile driving are expected, 

which includes a 10% buffer for 

possible delays (See table 1). Work is 

expected to occur 6 days a week over an 

11 hour workday. Pile driving would be 

completed only during the daylight 

hours. The majority of pile driving will 

be through vibratory methods. Any 

impact pile driving is restricted to occur 

from June 1 to November 30 to protect 

sensitive life stages of listed fish species 

in the area. 

Specific Geographic Region 

The Project Area is situated in the San 

Francisco Bay, about 3.7 miles (mi) (6 

km) from the entrance. The Project Area 

encompasses Pier 39, both the Pier 39 

East and West Basins, defined by 

existing breakwaters, and the intertidal 

and subtidal areas between Pier 39 and 

45 along the margin of San Francisco 

Bay. The Project Area is divided into 

five remedial response areas. This IHA 

is for work being done in Remedial 

Response Areas A and B. Remedial 

Response Area A is Pier 431⁄2 offshore 

area and western limit of the remedial 

response areas to the east of Pier 45, and 

Remedial Response Area B is Pier 43 

offshore area which includes two 

subareas (B1 and B2) (See Figure 1). All 

of the pile driving during the timeframe 

of this IHA will be in Remedial 

Response Area A except for the 

installation of eight turbidity curtain 

piles in Remedial Response Area B. 

BILLING CODE 3510–22–P 


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82838 Federal Register / Vol. 88, No. 226 / Monday, November 27, 2023 / Notices 

BILLING CODE 3510–22–C 

Figure 1—Project Location 

Detailed Description of the Specified 

Activity 

PG&E proposes to remediate 

sediments impacted with PAHs in order 

to protect human health and the 

environment. As noted above, this 

proposed IHA would authorize take 

associated with Year 1 of the Project 

only. This Project is expected to occur 

over a period of 5–7 years, and the 

phases will occur from west to east in 

the Project Area. 

PG&E expects that Year 1 of the 

Project will include installation of 

hydroacoustic data collection piles; 

installation of piles to attach a turbidity 

curtain; dredging of impacted sediment; 

installation of sediment pins to promote 

slope stability; capping of impacted 

sediment to be left in place; placement 

of armoring as needed; and relocation of 

the RWF, which will require the 

installation and removal of piles. 

PG&E expects, and NMFS concurs, 

that only pile driving activities will 

result in harassment of marine 

mammals. Underwater noises generated 

by dredging and capping is similar and 

within range of other background noise 

in San Francisco Bay and not 

anticipated to result in take of marine 

mammals. 

Activities that are expected to result 

in take are described below and in table 

2: 

• Hydroacoustic Data Collection—In 

order to collect hydroacoustic data, up 

to 10 18-inch composite plastic piles 

may be driven with an impact hammer 

during the approved anadromous fish 

work window between June 1 and 

November 30. The piles will be removed 

using vibratory methods. 

• Turbidity Curtain—During active 

dredging and capping operations, a 

turbidity curtain would be deployed 

across the full depth of the water 

column to minimize the potential for 

material loss outside the remedial 

response area. The turbidity curtain 


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Federal Register / Vol. 88, No. 226 / Monday, November 27, 2023 / Notices 82839 

would be attached to 20 temporary 

piles. These piles would consist of 

either H-piles or steel shell piles less 

than or equal to 24 inches (61 cm) in 

diameter and would be installed using 

vibratory pile driving. These piles 

would be removed using vibratory 

methods. 

• RWF Temporary Relocation— 

Relocation of the RWF would require 

removal of piles and overwater 

structures at the current location. 

Facilities would be reconstructed to the 

east side of Pier 45, which would 

require placement of eight 36-inch 

diameter guide piles and eight 24-inch 

diameter fender piles. All piles will be 

installed primarily using vibratory 

methods. If an impact hammer is 

required to seat piles, it would be 

restricted to only piles less than or equal 

to 24 inches (61 cm) in diameter, and 

attenuation (e.g., bubble curtain) would 

be used. Work would be restricted to 

June 1 to November 30 for impact pile 

driving. 

• Slope stabilization—Approximately 

120, 14 to 16-inch diameter tapered 

wood or composite sediment pins 

would be permanently installed using 

primarily vibratory methods with 

impact installation as needed to seat the 

piles. 

TABLE 1—SCHEDULE OF IN-WATER CONSTRUCTION

Type of pile Total number of pile installation/removal 

Number of piles 

installed/ 

removed per day 

Days of pile 

driving or removal 

Turbidity Curtain (Steel H-Piles or Steel Shell Pile 

≤24 inches).

40 (20 installed, 20 removed) ................................ 4 10 

RWF Temporary Relocation (Steel Shell Pile ≤24 

inches and 36 in Steel Shell Piles).

32 (16 installed, 16 removed) ................................ 4 8 

Sediment Pin Installation (14 to 16-inch timber or 

plastic).

120 (installation only) ............................................. 7 * 17 

Hydroacoustic Data Collection Piles (18-inch composite).20 (10 installed, 10 removed) ................................ 2 10 

Total ................................................................. 180 ......................................................................... .............................. 45 

Total (+10% buffer) .................................. ................................................................................. * 50 

* Rounded to maximum number of full days. 

TABLE 2—PILE INSTALLATION INFORMATION

Pile type Method Number piles Max piles/day 

Duration per 

pile 

(minutes) 

Strikes per pile 

Hydroacoustic Data Collection 

18-inch composite/plastic ...... Impact Installation ................. 10 .......................................... 10 N/A 400 

18-inch composite/plastic ...... Vibratory removal ................. 10 .......................................... 10 5 N/A 

Turbidity Curtain 1

Steel H-Pile ........................... Vibratory installation and removal.20 installed and removed ..... 4 10 N/A 

Steel Shell Pile ≤24 inches ... Vibratory installation and removal.20 installed and removed ..... 4 10 N/A 

RWF Temporary Relocation Piles 

Steel Shell Pile ≤24 inches ... Vibratory installation and removal.16 (8 installed, 8 removed) .. 4 10 N/A 

Steel Shell Pile ≤24 inches ... Impact installation if needed 8 ............................................ 4 N/A 400 

Steel Shell Pile 36 inches ..... Vibratory installation and removal.16 (8 installed, 8 removed) .. 4 20 N/A 

Sediment Pins 2

14 to 16-inch Timber ............. Vibratory installation ............. 120 ........................................ 20 20 N/A 

14 to 16-inch Composite/ 

Plastic.

Vibratory installation ............. 120 ........................................ 10 20 N/A 

14 to 16-inch Timber or 14 to 

16-inch Composite/Plastic.

Impact install if needed ........ 120 ........................................ 10 N/A 400 

1Turbidity curtain piles will either be H piles or steel shell piles less than or equal to 24 inches in diameter. 

2The sediment pins will either be timber or composite/plastic. 

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 


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regarding status and trends, distribution 

and habitat preferences, and behavior 

and life history of the potentially 

affected species. NMFS fully considered 

all of this information, and we refer the 

reader to these descriptions, instead of 

reprinting the information. Additional 

information regarding population trends 

and threats may be found in NMFS’ 

Stock Assessment Reports (SARs; 

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

national/marine-mammal-protection/ 

marine-mammal-stock-assessments) 

and more general information about 

these species (e.g., physical and 

behavioral descriptions) may be found 

on NMFS’ website (https://

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

Table 3 lists all species or stocks for 

which take is expected and proposed to 

be authorized for this activity, 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. 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’ SARs). While no 

serious injury or mortality is anticipated 

or proposed to be authorized here, PBR 

and annual serious injury and mortality 

from anthropogenic sources are 

included here as gross indicators of the 

status of the species or stocks 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’ 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’ U.S. Pacific and Alaska SARs. 

All values presented in table 3 are the 

most recent available at the time of 

publication and are available online at: 

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

national/marine-mammal-protection/ 

marine-mammal-stock-assessments. 

TABLE 3—MARINE MAMMAL SPECIES LIKELY IMPACTED BY THE SPECIFIED ACTIVITIES 1

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 2

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 3

PBR Annual 

M/SI 4

Family Delphinidae: 

Bottlenose dolphin .............. Tursiops truncatus .................... Coastal California ..................... -,-,N 453 (0.06, 346, 2011) ..... 2.7 ≥2.0 

Family Phocoenidae (porpoises): 

Harbor porpoise ......................... Phocoena phocoena ................. San Francisco-Russian River ... -,-,N 7,777 (0.62, 4811, 2017) 73 ≥0.4 

Order Carnivora—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 

Northern Fur Seal ............... Callorhinus ursinus ................... California ................................... -,-,N 14,050 (0.03, 7,524, 

2013).

451 1.8 

Northern Fur Seal ............... Callorhinus ursinus ................... Eastern North Pacific ................ -, D, Y 626,618 (0.2, 530,376, 

2021).

11,403 373 

Steller Sea Lion .................. Eumetopias jubatus .................. Eastern North Pacific ................ -,-,N 43,201 (N/A, 43,201, 

2017).

2,592 112 

Family Phocidae (earless seals): 

Harbor Seal ........................ Phoca vitulina ........................... California ................................... -,-,N 30,968 (N/A, 27,348, 

2014).

1,641 43 

Northern Elephant Seal ...... Mirounga angustirostris ............ California Breeding ................... -,-,N 187,386 (N/A, 85,369, 

2013).

5,122 13.7 

1 Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy’s Committee on Taxonomy 

(https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)). 2Endangered 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. 3 NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessmentreports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. 4These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, vessel strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. 

As indicated above, all seven species 

(with eight managed stocks) in table 3 

temporally and spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur. Gray whales 

and humpback whales rarely enter the 

Bay but may occasionally pass offshore 

of the Project Area. However, if either of 

these species are to approach the Level 

B zone construction will be shutdown. 

Therefore, no take is expected of these 

species, and these species will not be 

discussed further. 

Harbor Seal 

Pacific harbor seals are distributed 

from Baja California north to the 

Aleutian Islands of Alaska. Harbor seals 

do not make extensive pelagic 

migrations, but may travel hundreds of 

kilometers to find food or suitable 

breeding areas (Herder, 1986; Harvey 

and Goley, 2011; Carretta et al., 2023). 

Harbor seals are the most common 

marine mammal species observed in the 

Bay and occur year-round. Within the 

Bay they primarily use haulouts on 

exposed rocky ledges and on sloughs in 

the southern Bay. Harbor seals are 

central-place foragers (Orians and 

Pearson 1979) and tend to exhibit strong 

site fidelity within season and across 

years, generally forage close to haulout 

sites, and repeatedly visit specific 

foraging areas (Grigg et al., 2012; Suryan 


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and Harvey, 1998; Thompson et al., 

1998). Harbor seals in the Bay forage 

mainly within 7 mi (11.3 kilometers 

(km)) of their primary haulout site 

(Grigg et al. 2012), and often within just 

1–3 mi (1–5 km; Torok 1994). Harbor 

seals tend to forage at night and return 

to the haulout during the day with the 

peak in the afternoon between 1 p.m. 

and 4 p.m. (London et al, 2001; Stewart 

and Yochem, 1994; Yochem et al, 1987). 

The closest harbor seal haulout to the 

Project Area is Yerba Buena Island 

(YBI), approximately 4 km to the east of 

the Project Area. Although the YBI 

haulout is not expected to be within the 

area of ensonification, it is likely that 

foraging seals from this location would 

be present in the water during 

construction. 

Northern Elephant Seal 

Northern elephant seals range from 

southern California north to the Bering 

Sea, and west to the Okhotsk Sea and 

Honshu Island, Japan in the west 

(Carretta et al., 2023). They are common 

on California coastal mainland and 

island sites, where they pup, breed, rest, 

and molt. Northern elephant seals haul 

out to give birth and breed from 

December through March. Near the Bay, 

elephant seals breed, molt, and use the 

An ̃ o Nuevo Island haulout site, the 

Farallon Islands, and Point Reyes 

National Seashore. Northern elephant 

seals do not have any established 

haulout sites in the Bay. Generally, only 

juvenile elephant seals enter the Bay 

seasonally and do not remain long if 

they are healthy. Their diet is composed 

of small schooling fish such as walleye 

Pollock, herring, hake, anchovy, and 

squid. Diet and population trends vary 

with environmental conditions, such as 

El Nin ̃ o (Carretta et al., 2023). 

California Sea Lion 

California sea lions are found 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). Females and 

some juveniles tend to remain closer to 

rookeries (Atonelis et al., 1990; Melin et 

al., 2008). 

California sea lions have occupied KDock at Pier 39 in the Bay, adjacent to 

Area D of the Project Area, since 1987. 

No pupping has been observed here or 

at any other site in the Bay. Pier 39 is 

the only regularly used haulout site in 

the Project vicinity, but sea lions 

occasionally use human-made 

structures such as bridge piers, jetties, 

or navigation buoys (Riedman, 1990) as 

a haulout location. 

California sea lions feed seasonally on 

schooling fish and cephalopods, 

including salmon, herring, sardines, 

anchovy, mackerel, whiting, rockfish 

and squid (Lowry et al., 1990, 1991, 

2022; Weise 2000; Carretta et al., 2023) 

and can be seen foraging throughout the 

Bay. In central California sea lion 

populations, short term seasonal 

variations in diet are related to prey 

movement and life history patterns 

while long-term annual changes 

correlate to large-scale ocean climate 

shifts and foraging competition with 

commercial fisheries (Weise and 

Harvey, 2008; McClatchie et al. 2016). 

Conservation concerns for California sea 

lions include prey species availability 

due to climate change, vessel strikes, 

non-commercial fishery human caused 

mortality, hookworms, and competition 

for forage with commercial fisheries 

(Carretta et al., 2018; Carretta et al. 

2023). 

Northern Fur Seal 

Two northern fur seal stocks may 

occur near the Bay: the California and 

Eastern North Pacific stocks. The 

California stock breeds and pups on the 

offshore islands of California, and 

forages off the California coast. The 

Eastern Pacific stock breeds and pups 

on islands in the North Pacific Ocean 

and Bering Sea, but females and 

juveniles move south to California 

waters to forage in the fall and winter 

months (Gelatt and Gentry, 2018). Both 

the California and Eastern North Pacific 

stocks forage in the offshore waters of 

California, but usually only sick or 

emaciated juvenile fur seals seasonally 

enter the Bay in the fall and winter. Fur 

seals occasionally strand on YBI and 

Treasure Island, approximately 3.2 km 

from the Project Area. 

Steller Sea Lion 

Steller sea lions range along the North 

Pacific Rim from northern Japan to 

California. The eastern stock of Steller 

sea lions has historically bred on 

rookeries located in Southeast Alaska, 

British Columbia, Oregon, and 

California. Within the last several years 

a new rookery has become established 

on the outer Washington coast (Muto et 

al., 2020). The Steller sea lion is not 

common in the Bay, but occasionally 

Steller sea lions can be seen hauled out 

on Pier 39. Most recently, an adult male 

Steller sea lion was seen on the K-dock 

haulout in May 2023 (Segura, 2023). 

Bottlenose Dolphin 

Bottlenose dolphins are distributed 

world-wide in tropical and warmtemperate waters. The California coastal 

stock of common bottlenose dolphin is 

found within 0.6 mi (1 km) of shore 

(Defran and Weller, 1999) and occurs 

from northern Baja California, Mexico to 

Bodega Bay, CA. Their range has 

extended north over the last several 

decades with El Nin ̃ o events and 

increased ocean temperatures (Hansen 

and Defran, 1990) and spans as far north 

as Sonoma County (Keener et al., 2023). 

As the range of bottlenose dolphins 

extended north, dolphins began entering 

the Bay in 2010 (Szczepaniak, 2013). 

Bottlenose dolphins have been regularly 

observed in the western Central and 

South Bay, and between one and five 

dolphins are thought to be year-round 

residents of the Bay (Pacific Gas & 

Electric, 2023). An offshore common 

bottlenose dolphin stock exists, but 

genetic studies show that no mixing 

occurs between the two stocks 

(Lowther-Thieleking et al., 2015). 

Bottlenose dolphins are opportunistic 

foragers, and time of day, tidal state, and 

oceanographic habitat influence where 

they pursue prey (Hanson and Defran, 

1993). 

Harbor Porpoise 

In the Pacific, harbor porpoise are 

found in coastal and inland waters from 

Point Conception, California to Alaska 

and across to Kamchatka and Japan 

(Gaskin, 1984). Harbor porpoise appear 

to have more restricted movements 

along the western coast of the 

continental U.S. than along the eastern 

coast. The non-migratory San FranciscoRussian River stock ranges from 

Pescadero to Point Arena, California, 

utilizes relatively shallow nearshore 

waters (<100 meters), and feeds on 

small schooling fishes such as northern 

anchovy and Pacific herring which enter 

the Bay (Carretta et al., 2023; Stern et 

al., 2017). Harbor porpoises tend to 

occur in small groups and are 

considered to be relatively cryptic 

animals. 

Harbor porpoises are seen frequently 

outside the Bay and re-entered the Bay 

beginning in 2008 (Stern et al., 2017). 

They are now commonly seen yearround within the Bay in groups of two 

to five individuals, primarily on the 

west and northwest side of the Central 

Bay near the Golden Gate Bridge, near 

Marin County, and near the City of San 

Francisco (Duffy, 2015; Keener et al., 

2012; Stern et al., 2017) in the vicinity 

of the Project Area. Harbor porpoises are 

generally shallow, short-duration divers 

and must forage nearly continuously to 


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meet their high metabolic needs 

(Wisniewska et al. 2016). Harbor 

porpoise movements into the Bay are 

likely influenced by prey availability 

(Duffy 2015; Stern et al., 2017). 

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. Not all marine mammal 

species have equal hearing capabilities 

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

and Ketten, 1999; Au and Hastings, 

2008). To reflect this, Southall et al. 

(2007, 2019) recommended that marine 

mammals be divided into hearing 

groups based on directly measured 

(behavioral or auditory evoked potential 

techniques) or estimated hearing ranges 

(behavioral response data, anatomical 

modeling, etc.). 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 4. 

TABLE 4—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. 

Potential Effects of Specified Activities 

on Marine Mammals and Their Habitat 

This section provides a discussion of 

the ways in which components of the 

specified activity may impact marine 

mammals and their habitat. The 

Estimated Take of Marine Mammals 

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 of Marine Mammals 

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 whether those 

impacts are reasonably expected to, or 

reasonably likely to, adversely affect the 

species or stock through effects on 

annual rates of recruitment or survival. 

Acoustic effects on marine mammals 

during the specified activities can occur 

from impact pile driving and vibratory 

pile driving and removal. The effects of 

underwater noise from PG&E’s proposed 

activities have the potential to result in 

Level B harassment of marine mammals 

in the project 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 (American National Standards 

Institute (ANSI), 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 

activities 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 and vibratory pile 

driving and removal. The sounds 

produced by these activities fall into 

one of two general sound types: 

impulsive and non-impulsive. 

Impulsive sounds (e.g., explosions, 

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

operations such as drilling or dredging, 

vibratory pile driving, underwater 


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chainsaws, 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). 

Two types of hammers would be used 

on this project, impact and vibratory. 

Impact hammers operate by repeatedly 

dropping and/or pushing a heavy piston 

onto a pile to drive the pile into the 

substrate. Sound generated by impact 

hammers is considered impulsive. 

Vibratory hammers install piles by 

vibrating them and allowing the weight 

of the hammer to push them into the 

sediment. Vibratory hammers produce 

non-impulsive, continuous sounds. 

Vibratory hammering generally 

produces sound pressure levels (SPLs) 

10 to 20 dB lower than 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). 

The likely or possible impacts of 

PG&E’s proposed activities on marine 

mammals could be generated from both 

non-acoustic and acoustic stressors. 

Potential non-acoustic stressors include 

the physical presence of the equipment 

and personnel; however, we expect that 

any animals that approach the project 

site close enough to be harassed due to 

the presence of equipment or personnel 

would be within the Level B harassment 

zones from pile driving and would 

already be subject to harassment from 

the in-water activities. Therefore, any 

impacts to marine mammals are 

expected to primarily be acoustic in 

nature. Acoustic stressors are generated 

by heavy equipment operation during 

pile driving activities (i.e., impact and 

vibratory pile driving and removal). 

Acoustic Impacts 

The introduction of anthropogenic 

noise into the aquatic environment from 

pile driving equipment is the primary 

means by which marine mammals may 

be harassed from PG&E’s specified 

activities. 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 as 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. non-impulsive), the species, age and 

sex class (e.g., adult male vs. mother 

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 et al., 2008). PTS 

levels for marine mammals are 

estimates, because there are limited 

empirical data measuring PTS in marine 

mammals (e.g., Kastak et al., 2008), 

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) 

TTS is 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-to-session 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). At low frequencies, onset-TTS 

exposure levels are higher compared to 

those in the region of best sensitivity 

(i.e., a low frequency noise would need 

to be louder to cause TTS onset when 

TTS exposure level is higher), as shown 

for harbor porpoises and harbor seals 

(Kastelein et al., 2019a, 2019b, 2020a, 

2020b). In addition, TTS can 

accumulate across multiple exposures, 

but the resulting TTS will be less than 

the TTS from a single, continuous 

exposure with the same SEL (Finneran 

et al., 2010; Kastelein et al., 2014; 

Kastelein et al., 2015; Mooney et al., 

2009). This means that TTS predictions 

based on the total, cumulative SEL will 

overestimate the amount of TTS from 

intermittent exposures such as sonars 

and impulsive sources. 

The potential for TTS from impact 

pile driving exists. After exposure to 

playbacks of impact pile driving sounds 

(rate 2,760 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 noiseinduced hearing loss for mysticetes. 

Nonetheless, what we considered is the 

best available science. For summaries of 

data on TTS in marine mammals or for 

further discussion of TTS onset 

thresholds, please see Southall et al. 

(2007, 2019), Finneran and Jenkins 

(2012), Finneran (2015), and table 5 in 

NMFS (2018). 

Activities for this project include 

impact and vibratory pile driving, and 

vibratory pile removal. There would 

likely be pauses in activities producing 

the sound during each day. Given these 

pauses and the fact that many marine 

mammals are likely moving through the 

project areas 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); or avoidance 

of areas where sound sources are 

located. Pinnipeds may increase their 

haul-out time, possibly to avoid inwater 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, 2021; 

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) as well as 

Nowacek et al. (2007); Ellison et al. 

(2012), and Gomez et al. (2016) 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; Melco ́n et al., 2012). In 

addition, behavioral state of the animal 

plays a role in the type and severity of 

a behavioral response, such as 

disruption to foraging (e.g., Sivle et al., 

2016; Wensveen et al., 2017). 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 (Goldbogen 

et al., 2013). 

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., Selye, 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). 

Increases in the circulation of 


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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 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 these projects 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 masking of communication 

signals by anthropogenic noise may be 

considered as a reduction in the 

communication space of animals (e.g., 

Clark et al., 2009) and may result in 

energetic or other costs as animals 

change their vocalization behavior (e.g., 

Miller et al., 2000; Foote et al., 2004; 

Parks et al., 2007; Di Iorio and Clark, 

2010; Holt et al., 2009). The Bay is 

heavily used by commercial, 

recreational, and military vessels, and 

background sound levels in the area are 

already elevated. Due to the transient 

nature of marine mammals to move and 

avoid disturbance, masking is not likely 

to have long-term impacts on marine 

mammal species within the proposed 

project area. 

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 likely 

previously have been ‘‘taken’’ because 

of exposure to underwater sound above 

the behavioral harassment thresholds, 

which are generally 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 

PG&E’s proposed construction 

activities could have localized, 

temporary impacts on marine mammal 

habitat, including 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 areas (see discussion below). 

During impact and vibratory pile 

driving or removal, elevated levels of 

underwater noise would ensonify the 

project area 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 

expected to be 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 driving is localized 

to about a 25 feet (ft) (7.6-m) radius 

around the pile (Everitt et al., 1980). 

Cetaceans are not expected to be close 

enough to the pile driving areas to 

experience effects of turbidity, and any 

pinnipeds could avoid localized areas of 

turbidity. Local 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 


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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 

proposed action is relatively small 

compared to the total available habitat 

in the Bay. The proposed project area is 

highly influenced by anthropogenic 

activities and provides limited foraging 

habitat for marine mammals. 

Furthermore, pile driving and removal 

at the proposed project site would not 

obstruct long-term 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 and 

marine mammal 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 prey of the disturbed area would still 

leave significantly large areas of 

potential 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, other marine mammals). 

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; several are 

based on studies in support of large, 

multiyear bridge construction projects 

(e.g., Scholik and Yan, 2001, 2002; 

Popper and Hastings, 2009). Many 

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). In response 

to pile driving, Pacific sardines and 

northern anchovies may exhibit an 

immediate startle response to individual 

strikes, but return to ‘‘normal’’ pre-strike 

behavior following the conclusion of 

pile driving with no evidence of injury 

as a result (appendix C in NAVFAC SW, 

2014). 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; Popper et al., 2005). 

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). 

The most likely impact to fishes from 

pile driving and removal and 

construction activities at the project area 

would be temporary behavioral 

avoidance of the area. The duration of 

fish avoidance of this area after pile 

driving stops is unknown, but a rapid 

return to normal recruitment, 

distribution, and behavior is 

anticipated. In general, impacts to 

marine mammal prey species are 

expected to be minor and temporary. 

Further, it is anticipated that 

preparation activities for pile driving or 

removal (i.e., positioning of the 

hammer, clipper or wire saw) and upon 

initial startup of devices would cause 

fish to move away from the affected area 

outside areas where injuries may occur. 

Therefore, relatively small portions of 

the proposed project area would be 

affected for short periods of time, and 

the potential for effects on fish to occur 

would be temporary and limited to the 

duration of sound-generating activities. 

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 actions 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 potential areas 

fish and marine mammal foraging 

habitat in the nearby vicinity. Thus, we 

conclude that impacts of the specified 

activities 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 of Marine Mammals 

This section provides an estimate of 

the number of incidental takes proposed 

for authorization through the IHA, 

which will inform both NMFS’ 

consideration of ‘‘small numbers,’’ and 

the negligible impact determinations. 

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, 

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 only, in the form of 

disruption of behavioral patterns and/or 

TTS for individual marine mammals 

resulting from exposure to vibratory and 

impact pile driving. Based on the nature 

of the activity and the anticipated 

effectiveness of the mitigation measures 

(i.e., shutdown) discussed in detail 

below in the Proposed Mitigation 


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section, Level A harassment is neither 

anticipated nor proposed to be 

authorized. 

As described previously, no serious 

injury or mortality is anticipated or 

proposed to be authorized for this 

activity. Below we describe how the 

proposed take numbers are estimated. 

For acoustic impacts, generally 

speaking, we estimate take by 

considering: (1) acoustic thresholds 

above which NMFS believes the best 

available science indicates 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) the number of days of activities. 

We note that while these factors can 

contribute to a basic calculation to 

provide an initial prediction of potential 

takes, additional information that can 

qualitatively inform take estimates is 

also sometimes available (e.g., previous 

monitoring results or average group 

size). Below, we describe the factors 

considered here in more detail and 

present the proposed take estimates. 

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—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 or exposure 

context (e.g., frequency, predictability, 

duty cycle, duration of the exposure, 

signal-to-noise ratio, distance to the 

source), the environment (e.g., 

bathymetry, other noises in the area, 

predators in the area), and the receiving 

animals (hearing, motivation, 

experience, demography, life stage, 

depth) and can be difficult to predict 

(e.g., Southall et al., 2007, 2021; Ellison 

et al., 2012). Based on what the 

available science indicates and the 

practical need to use a threshold based 

on a metric that is both predictable and 

measurable for most activities, NMFS 

typically uses a generalized acoustic 

threshold based on received level to 

estimate the onset of behavioral 

harassment. NMFS generally predicts 

that marine mammals are likely to be 

behaviorally harassed in a manner 

considered to be Level B harassment 

when exposed to underwater 

anthropogenic noise above root-meansquared pressure received levels (RMS 

SPL) of 120 dB (referenced to 1 

micropascal (re 1 mPa)) for continuous 

(e.g., vibratory pile driving, drilling) and 

above RMS SPL 160 dB re 1 mPa for nonexplosive impulsive (e.g., seismic 

airguns) or intermittent (e.g., scientific 

sonar) sources. Generally speaking, 

Level B harassment take estimates based 

on these behavioral harassment 

thresholds are expected to include any 

likely takes by TTS as, in most cases, 

the likelihood of TTS occurs at 

distances from the source less than 

those at which behavioral harassment is 

likely. TTS of a sufficient degree can 

manifest as behavioral harassment, as 

reduced hearing sensitivity and the 

potential reduced opportunities to 

detect important signals (conspecific 

communication, predators, prey) may 

result in changes in behavior patterns 

that would not otherwise occur. 

PG&E’s proposed activity includes the 

use of continuous (vibratory pile 

driving) and impulsive (impact pile 

driving) sources, and therefore the RMS 

SPL thresholds of 120 and 160 dB re 1 

mPa are applicable. 

Level A harassment—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). PG&E’s proposed activity 

includes the use of impulsive (impact 

pile driving) and non-impulsive 

(vibratory pile driving) sources. 

These thresholds are provided in the 

table below. 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/ 

marine-mammal-acoustic-technicalguidance. 

TABLE 5—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

PTS onset acoustic thresholds *

(received level) 

Hearing group 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 are used in estimating the area 

ensonified above the acoustic 

thresholds, including 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., pile driving and 

removal). 

The project includes vibratory pile 

installation and removal and impact 

pile driving. Source levels for these 

activities are based on reviews of 

measurements of the same or similar 

types and dimensions of piles available 

in the literature. Source levels for each 

pile size and activity are presented in 

table 6. Source levels for vibratory 

installation and removal of piles of the 

same diameter are conservatively 

assumed to be the same. 

The majority of source levels were 

selected from a single source, as shown 

in table 6 below. For the vibratory 

installation of 36-inch steel shell piles 

and vibratory installation of timber 

piles, NMFS determined it appropriate 

to use an average of source levels. 

NMFS reviewed all available monitoring 

reports of vibratory driving of 36-inch 

steel piles in San Francisco Bay (Gast 

&Associated Environmental 

Consultants, 2021, 2023; Illingworth & 

Rodkin, 2018, 2020). Averaging of 

sound levels was performed by first 

converting from dB to linear units of 

pressure (Pascals [Pa]), averaging, and 

converting back to dB. The mean RMS 

level at 10m for San Francisco Bay was 

approximately 168 dB re 1 Pa RMS. 

Therefore, NMFS has selected this 

average value as the most appropriate 

value for vibratory driving of 36-inch 

steel pipe piles during the proposed 

project. With regard to vibratory 

installation of timber piles, there are 

limited data available, and none from 

San Francisco Bay. Therefore, NMFS 

evaluated all available timber pile data 

(three projects from Puget Sound, WA, 

and one project from Norfolk, VA) 

(Greenbusch Group, 2018; Illingworth 

and Rodkin, 2017; Laughlin, 2011; U.S. 

Navy, 2016) and calculated the mean 

and maximum RMS values for each 

project and for all projects together. The 

overall mean RMS value was 

approximately 158 dB re 1 Pa RMS. 

NMFS therefore selected this as an 

appropriate proxy value for vibratory 

driving of timber piles during the 

proposed project. 

TABLE 6—SOUND SOURCE LEVELS FOR PILE DRIVING ACTIVITIES 1

Pile type Method 

Peak sound 

pressure 

(dB re 1 μPa) 

RMS 

(dB re 1 μPa) 

SEL 

(dB re 1 μPa2 

sec) 

Source 

Hydroacoustic Data Collection 

18-inch composite/plastic ...... Impact Install ........................ 185 160 150 Caltrans, 2020; extrapolated 

from 13-inch composite. 

18 inch composite/plastic ...... Vibratory Removal ................ N/A 152 N/A WSDOT, 2012; 13-inch composite used as proxy. 

Turbidity Curtain 

Steel H-Pile ........................... Vibratory Install and Removal.N/A 143 N/A Caltrans, 2020. 

Steel Shell Pile ≤24 inches ... Vibratory Install and Removal.N/A 153 N/A Caltrans, 2020; 24-inch pipe 

pile used as proxy. 

RWF Relocation 

24 inch steel shell ................. Vibratory Installation and Removal.N/A 153 N/A Caltrans, 2020. 

24 inch steel shell ................. Impact Installation 2 .............. 208 193 178 Illingworth & Rodkin, Inc. 

2014. 

36 inch steel shell ................. Vibratory Installation and Removal.N/A 168 N/A Gast & Associated Environmental Consultants, 2021, 

2023; Illingworth and 

Rodkin, 2018, 2020. See 

explanation above. 

Slope Stabilization 

14–16 inch Timber ................ Vibratory ............................... N/A 158 N/A Greenbusch Group, 2018; 

Illingworth and Rodkin, 

2017; Laughlin, 2011; U.S. 

Navy 2016. See explanation above. 

14–16 inch Timber ................ Impact ................................... 184 157 145 Caltrans, 2020. 

14–16 in Composite .............. Vibratory ............................... N/A 152 N/A WSDOT, 2012. 13-inch composite used as proxy. 

14–16 inch Composite ........... Impact ................................... 177 153 145 Caltrans, 2020. 

1All values are at 10 m from the source. 

2PG&E would use a bubble curtain attenuation system for impact pile driving of the RWF 24-inch steel shell piles, and we conservatively assumes a 5 dB reduction in source level from those presented here due to use of the attenuation system. 


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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 topography. The 

general formula for underwater TL is: 

TL = B * Log10 (R1/R2), 

Where: 

TL = transmission loss in dB; 

B = transmission loss coefficient; 

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, known as practical 

spreading. As is common practice in 

coastal waters, here we assume practical 

spreading (4.5 dB reduction in sound 

level for each doubling of distance) for 

all impact and vibratory installation and 

removal of piles with the exception of 

vibratory installation and removal of the 

36-inch steel pipe piles in the RWF 

Relocation. Illingworth & Rodkin 

conducted hydro-acoustic monitoring 

for the 2017 WETA Downtown San 

Francisco Ferry Terminal Expansion 

Project and calculated a TL coefficient 

of 18.7 for vibratory installation of 36- 

inch steel shell piles (Illingworth & 

Rodkin, 2018). Given the proximity to 

the project area, PG&E determined that 

18.7 was an appropriate transmission 

coefficient to use for the vibratory 

installation of the 36-inch steel shell 

pile, and NMFS concurs. 

The ensonified area associated with 

Level A harassment is more technically 

challenging to predict due to the need 

to account for a duration component. 

Therefore, NMFS developed an optional 

User Spreadsheet tool to accompany the 

Technical Guidance that can be used to 

relatively simply predict an isopleth 

distance for use in conjunction with 

marine mammal density or occurrence 

to help predict potential takes. We note 

that because of some of the assumptions 

included in the methods underlying this 

optional tool, we anticipate that the 

resulting isopleth estimates are typically 

going to be overestimates of some 

degree, which may result in an 

overestimate of potential take by Level 

A harassment. However, this optional 

tool offers the best way to estimate 

isopleth distances when more 

sophisticated modeling methods are not 

available or practical. For stationary 

sources such as pile driving, the 

optional User Spreadsheet tool predicts 

the distance at which, if a marine 

mammal remained at that distance for 

the duration of the activity, it would be 

expected to incur PTS. Source levels are 

provided above in table 6. Inputs used 

in the optional User Spreadsheet tool 

are provided below in table 7. Resulting 

estimated Level A and B harassment 

isopleths are provided in table 8. 

TABLE 7—USER SPREADSHEET INPUTS

[Source levels provided in Table 6] 

Pile type Method Duration Piles/day 

Hydroacoustic Data Collection 

18-inch composite/plastic ....................... Impact Install ......................................... 400 strikes/pile ...................................... 10 

18 inch composite/plastic ....................... Vibratory Removal ................................. 20 minutes ............................................. 10 

Turbidity Curtain 

Steel H-Pile ............................................ Vibratory ................................................ 10 minutes ............................................. 4 

Steel Shell Pile ≤24 inches .................... Vibratory ................................................ 10 minutes ............................................. 4 

RWF Relocation 

24 inch steel shell .................................. Vibratory ................................................ 10 minutes ............................................. 4 

24 inch steel shell .................................. Impact .................................................... 400 strikes/pile ...................................... 4 

36 inch steel shell .................................. Vibratory ................................................ 20 minutes ............................................. 4 

Sediment Pin Installation 

Timber .................................................... Vibratory ................................................ 20 minutes ............................................. 20 

Timber .................................................... Impact .................................................... 400 strikes/pile ...................................... 20 

14–16 inch Composite ........................... Vibratory ................................................ 20 minutes ............................................. 10 

14–16 inch Composite ........................... Impact .................................................... 400 strikes/pile ...................................... 10 

TABLE 8—LEVEL A HARASSMENT AND LEVEL B HARASSMENT ISOPLETHS FROM VIBRATORY AND IMPACT PILE DRIVING

Pile type & method 

Level A/PTS isopleth 

(m) 

Level B 

isopleth 

(m) 

Level B area 

of 

ensonification 

(km2) 

Hearing groups 

Cetaceans Pinnipeds 

LF MF HF Phocids Otariids 

Hydroacoustic Data Collection Piles 

18-inch composite (Impact) ........................... 16 <1 19 9 <1 10 <0.01 

18-inch Composite (Vibratory) ...................... 4 <1 6 3 <1 1,360 3.58 

Turbidity Curtain 

Steel H-Pile (Vibratory) ................................. <1 0 <1 <1 <1 341 0.29 


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TABLE 8—LEVEL A HARASSMENT AND LEVEL B HARASSMENT ISOPLETHS FROM VIBRATORY AND IMPACT PILE DRIVING— 

Continued 

Pile type & method 

Level A/PTS isopleth 

(m) 

Level B 

isopleth 

(m) 

Level B area 

of 

ensonification 

(km2) 

Hearing groups 

Cetaceans Pinnipeds 

LF MF HF Phocids Otariids 

Steel Shell Pile ≤ 24 inches (Vibratory) ........ 2 <1 4 2 <1 1,585 4.61 

RWF Temporary Relocation Piles 

24-inch Steel Shell Pile (Vibratory) ............... 2 <1 4 2 <1 1,585 4.54 

24-inch Steel Shell Pile (Impact, Attenuated)* ......................................................... 294 11 351 158 12 736 1.06 

36-inch Steel Shell Pile (Vibratory) ............... 20 3 28 14 2 3,688 23.46 

Sediment Pins 

14 to 16-inch Timber Pile (Vibratory) ............ 16 2 23 10 1 3,415 19.17 

14 to 16-inch Timber Pile (Impact) ............... 12 <1 14 6 <1 6 <0.01 

14 to 16-inch Composite Pile (Vibratory) ...... 4 <1 6 3 <1 1,360 3.2 

14 to 16-Inch Composite Pile (Impact) ......... 7 <1 9 4 <1 3.4 <0.01 

* 5 dB reduction in sound due to use of bubble curtain assumed. 

Marine Mammal Occurrence 

In this section we provide information 

about the occurrence of marine 

mammals, including density or other 

relevant information which will inform 

the take calculations. 

Because reliable marine mammal 

density information is not available for 

the San Francisco Bay, several datasets 

were used to attain estimates of the 

abundance of marine mammals in the 

Bay. Datasets used included 5 years of 

sighting and stranding data from The 

Marine Mammal Center (TMMC) 

(NMFS, 2021a); 5 years of sighting and 

stranding data from the California 

Academy of Sciences (CAS) (NMFS, 

2021b); citizen-reported live sightings 

from iNaturalist.org; 5 days of sighting 

data during sediment investigation in 

2020 during the initial phase of the 

project (Haase, 2021); and counts from 

haulouts. Data from all sources, when 

available, were considered. Depending 

on the distribution of sightings and 

granularity of data, different sources 

have been used to estimate the number 

of individuals of each species with the 

potential to occur in vicinity of the 

project. The largest ensonified area is 

during vibratory installation of 36-inch 

steel shell piles, which results in a 3,688 

m isopleth and 23.46 km2 area of 

ensonification. 

Harbor Seal 

Harbor seals in the Bay forage mainly 

within 7.0 mi (11.3 km) of their primary 

haulout site (Grigg et al. 2012), and 

often within just 1–3 miles (1–5 km) 

(Torok, 1994). The only harbor seal 

haulout within 7 miles (11.3 km) of the 

project site is YBI, which is 3.1 mi (5 

km) to the east of the Project Area. Noise 

from the project is not expected to reach 

the haulout, however, harbor seals that 

use this haulout are likely to forage 

within ensonified areas from the project. 

Harbor seal take estimates were based 

on observations conducted by Marine 

Mammal Observers (MMOs) over a 5 

day period in 2020, during sediment 

investigation in the initial phase of the 

project, within remedial response areas 

A, B, and C (See Haase, 2021). A 

maximum of 20 harbor seals were 

observed per day. PG&E therefore 

estimates 20 harbor seals per day within 

the project area per day. NMFS concurs 

with this assumption. 

Northern Elephant Seal 

TMMC recorded 903 elephant seals in 

the Bay from 2016 to 2021 (NMFS, 

2021a). The CAS reported an additional 

6 for a total of 909 over 5 years in the 

Bay from 2016 to 2021 (NMFS, 2021b), 

yielding an average of 0.5 elephant seals 

per day. To ensure sufficient 

authorization of take of northern 

elephant seals, PG&E assumed 0.5 

elephant seals will occur in the area per 

day (i.e., one elephant seal every 2 

days). NMFS concurs with this 

assumption. 

California Sea Lion 

The Pier 39 K-Dock haulout is the 

only regularly used California Sea Lion 

haulout in the vicinity of the Project 

Area, adjacent to Area C. The Sea Lion 

Center at Pier 39 regularly counted the 

sea lions at K-Dock from 1991 through 

2018. From 2016 through 2018, the 

yearly average ranged from 89 to 229 

animals per day. The average per day 

over all 3 years was 191 sea lions 

(Pacific Gas & Electric, 2023). Although 

there are times of the year when the Kdock is unoccupied or there are few 

individuals present, it is difficult to 

predict abundance based on time of 

year. In order to ensure sufficient 

authorization of sea lions, PG&E is 

assuming a local abundance estimate of 

191 sea lions per day within the 

estimated harassment area, and NMFS 

concurs. 

Northern Fur Seal 

TMMC recorded 44 northern fur seals 

in the Bay from 2016 to 2021 (NMFS, 

2021a). CAS recorded an additional 3 

for a total of 47 over 5 years (NMFS, 

2021b), yielding 0.03 per day, or 

approximately 10 per year. In the fall 

and winter, northern fur seals 

occasionally strand on YBI and Treasure 

Island (Pacific Gas & Electric, 2023), 

approximately 2.0 mi (3.2 km) from the 

project area. Using PG&E’s assumption 

of approximately 0.03 fur seals per day 

over the course of 50 days of pile 

driving plus known fur seal strandings 

near the project area, NMFS has 

determined it appropriate to assume five 

fur seals in the project area during the 

project time period. 

Steller Sea Lion 

Steller sea lions are rare in San 

Francisco Bay. TMMC recorded four 

Steller sea lions in the Bay from 2016 to 

2021 (NMFS, 2021a), while CAS 

reported no Steller sea lions during this 

time (NMFS, 2021b). In 2020 and 2021, 

INaturalist.org recorded four Steller sea 

lions in the Bay. On rare occasions, 

Steller sea lions are seen on the Pier 39 

K-dock haulout. An adult male was 

spotted there in May 2023 (Segura, 

2023) and in previous years a single 


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male Steller sea lion had been observed 

using the Pier 39 K-dock haulout 

intermittently during July and August 

and occasionally September (Pacific Gas 

& Electric, 2023). Given these known 

occasional occurrences of the Steller sea 

lion at Pier 39, PG&E feels it is 

appropriate to assume five Steller sea 

lions in the project area during the time 

period of the project, and NMFS 

concurs. 

Bottlenose Dolphins 

Historically, observations of 

bottlenose dolphins have occurred west 

of Treasure Island and were 

concentrated in the Project vicinity 

along the nearshore area of San 

Francisco south to Redwood City. Since 

2016, one individual has been regularly 

seen near the former Alameda Air 

Station and five animals were regularly 

seen in the summer and fall of 2018 in 

the same location (Pacific Gas & 

Electric, 2023). A recent study reports 

that dolphins have been sighted in the 

vicinity of the Golden Gate Bridge, 

around Yerba Buena and Angel Islands, 

and in the central Bay (Keener et al., 

2023). PG&E is assuming that one group 

of bottlenose dolphins will enter into 

the project isopleth per month of pile 

driving, and NMFS concurs. A group 

size is estimated to be five animals 

based on sightings of bottlenose 

dolphins in the Bay (Pacific Gas & 

Electric, 2023). 

Harbor Porpoise 

Harbor porpoises are primarily seen 

near the Golden Gate Bridge, Marin 

County, and the city of San Francisco on 

the northwest side of the Bay (Keener et 

al., 2012; Stern et al., 2017), in the 

vicinity of the project area. Limited data 

exists on the abundance of harbor 

porpoises in the Bay, and therefore data 

from MMOs in 2020 was used (see 

Haase 2021). An individual harbor 

porpoise was seen in the project zone on 

2 of the 5 days, and a group of two 

individuals was reported on a separate 

day of the 5 day observation period 

(Haase, 2021). To ensure sufficient 

authorization of take of harbor porpoise, 

it is estimated that two harbor porpoises 

will occur within the estimated 

harassment area per day. 

Take Estimation 

Here we describe how the information 

provided above is synthesized to 

produce a quantitative estimate of the 

take that is reasonably likely to occur 

and proposed for authorization. 

Take estimate calculations vary by 

species. To calculate take by Level B 

harassment for harbor seals, California 

sea lions, northern elephant seals, and 

harbor porpoises, NMFS multiplied the 

daily occurrence estimates described in 

the Marine Mammal Occurrence section 

by the number of project days (table 9). 

For northern fur seals, PG&E is 

assuming a total of five animals in the 

area of the project during the duration 

of the project, based on sightings in the 

Bay and known strandings on YBI (see 

Marine Mammal Occurrence above), 

and is therefore requesting, and NMFS 

is proposing to authorize, take of five 

northern fur seals by Level B 

harassment (table 9). 

Although Steller sea lions are rare in 

San Francisco Bay, based on sighting 

data and known occurrence of Steller 

sea lions on the Pier 39 K-dock haulout 

(PG&E, 2023; Segura, 2023), PG&E is 

conservatively requesting five takes by 

Level B harassment of Steller sea lions 

during the time period of the project, 

and NMFS concurs (table 9). 

For bottlenose dolphins, PG&E 

estimates that one group of five 

bottlenose dolphins may be taken by 

Level B harassment per month of pile 

driving. Based on 5 months of pile 

driving, NMFS proposes to authorize 25 

takes by Level B harassment of 

bottlenose dolphins. 

TABLE9—ESTIMATED TAKE BY LEVEL B HARASSMENT PROPOSED FOR AUTHORIZATION AND ESTIMATED TAKE AS A

PERCENTAGE OF THE POPULATION

Species Stock Expected occurrence Estimated 

Level B take 

Stock abundance 

* Percent of stock 

Pacific Harbor Seal ......... California ......................... 20 seals per day ............. 1000 30,968 3.2 

Northern Elephant Seal ... California Breeding ......... 0.5 seals per day ............ 25 187,386 0.01 

California Sea Lion .......... United States .................. 191 sea lions per day ..... 9,550 257,606 3.7 

Northern Fur Seal ........... California; Eastern North 

Pacific.

5 seals over project duration.5 14,050; 626,618 0.04; 0.001 

Steller sea lion ................ Eastern United States .... 5 sea lions over project 

duration.

5 43,201 0.01 

Bottlenose dolphin ........... Coastal California ........... 5 dolphins per month of 

project.

25 453 5.5 

Harbor Porpoise .............. San Francisco-Russian 

River.

2 porpoises per day ........ 100 7,777 1.3 

* NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. 

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, NMFS considers 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 


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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 and 

impact on operations. 

PG&E must follow mitigation 

measures as specified below. 

PG&E must ensure that construction 

supervisors and crews, the monitoring 

team, and relevant PG&E staff are 

trained prior to the start of all pile 

driving activities, so that 

responsibilities, communication 

procedures, monitoring protocols, and 

operational procedures are clearly 

understood. New personnel joining 

during the project must be trained prior 

to commencing work. 

Shutdown Zones 

PG&E must establish shutdown zones 

and Level B monitoring zones for all 

pile driving 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 animal (or in anticipation of an 

animal entering the defined area). 

Shutdown zones are based on the largest 

Level A harassment zone for each pile 

size/type and driving method, and 

behavioral monitoring zones are meant 

to encompass Level B harassment zones 

for each pile size/type and driving 

method, as shown in table 8. A 

minimum shutdown zone of 10 m 

would be required for all in-water 

construction activities to avoid physical 

interaction with marine mammals, and 

the radii of the shutdown zones are 

rounded to the next largest 10 m 

interval in comparison to the Level zone 

for each activity type. Marine mammal 

monitoring will be conducted during all 

pile driving activities to ensure that 

marine mammals do not enter Level A 

shutdown zones, that marine mammal 

presence in the isopleth does not exceed 

authorized take, and to prevent take of 

the humpback and gray whale. Proposed 

shutdown zones for each activity type 

are shown in table 10. 

Prior to pile driving, shutdown zones 

and monitoring zones will be 

established based on zones represented 

in table 10. Observers will survey the 

shutdown zones for at least 30 minutes 

before pile driving activities start. If 

marine mammals are found within the 

shutdown zone, pile driving will be 

delayed until the animal has moved out 

of the shutdown zone, either verified by 

an observer or by waiting until 15 

minutes has elapsed without a sighting. 

If a marine mammal approaches or 

enters the shutdown zone during pile 

driving, the activity will be halted. Pile 

driving may resume after the animal has 

moved out of and is moving away from 

the shutdown zone or after at least 15 

minutes has passed since the last 

observation of the animal. 

All marine mammals would be 

monitored in the Level B harassment 

zones and throughout the area as far as 

visual monitoring can take place. If a 

marine mammal enters the Level B 

harassment zone, in-water activities 

would continue and PSOs would 

document the animal’s presence within 

the estimated harassment zone. 

If a species for which authorization 

has not been granted (i.e., gray whale or 

humpback whale), or a species which 

has been granted but the authorized 

takes are met, is observed approaching 

or within the Level B monitoring zone, 

pile driving activities will be shutdown 

immediately. Activities will not resume 

until the animal has been confirmed to 

have left the area or 15 minutes has 

elapsed with no sighting of the animal. 

TABLE 10—SHUTDOWN ZONES AND LEVEL B MONITORING ZONES BY ACTIVITY

Pile type and method 

Shutdown zone 

for all species 

(m) 

Monitoring zone 

(m) 

Hydroacoustic Data Collection Piles: 

18-inch Composite/Plastic (impact) ...................................................................................................... 20 10 

18-Inch Composite/Plastic (vibratory removal) .................................................................................... 10 1,360 

Turbidity Curtain: 

Steel H-Pile (Vibratory Install and Removal) ....................................................................................... 10 341 

24-inch steel shell pile (Vibratory install and removal) ........................................................................ 10 1,585 

RWF Relocation Piles: 

24-inch steel shell pile (Vibratory install and removal) ........................................................................ 10 1,585 

24-inch steel shell pile (impact-attenuated) ......................................................................................... 360 736 

36-inch steel shell pile (vibratory) ........................................................................................................ 30 3,688 

Sediment Pins: 

14–16 inch timber (Vibratory) ............................................................................................................... 30 3,415 

14–16 inch timber (impact) ................................................................................................................... 20 10 

14–16 inch composite (impact) ............................................................................................................ 10 10 

14–16 inch composite (vibratory install) ............................................................................................... 20 1,360 

Protected Species Observers 

The placement of PSOs during all pile 

driving activities (described in the 

Proposed Monitoring and Reporting 

section) would ensure that the entire 

shutdown zone is visible. Should 

environmental conditions deteriorate 

such that the entire shutdown zone 

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

rain), pile driving would be delayed 

until the PSO is confident marine 

mammals within the shutdown zone 

could be detected. 

PSOs would monitor the full 

shutdown zones and as much of the 

Level B harassment zones as possible. 

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 areas outside 

the shutdown zones and thus prepare 

for a potential cessation of activity 

should the animal enter the shutdown 

zone. 

Pre- and Post-Activity Monitoring 

Monitoring must take place from 30 

minutes prior to initiation of pile 

driving activities (i.e., pre-clearance 

monitoring) through 30 minutes postcompletion of pile driving. Prior to the 

start of daily in-water construction 

activity, or whenever a break in pile 

driving of 30 minutes or longer occurs, 

PSOs would observe the shutdown and 

monitoring zones for a period of 30 

minutes. The shutdown zone would be 

considered cleared when a marine 

mammal has not been observed within 


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the zone for a 30-minute period. If a 

marine mammal is observed within the 

shutdown zones, pile driving activity 

would be delayed or halted. If work 

ceases for more than 30 minutes, the 

pre-activity monitoring of the shutdown 

zones would commence. A 

determination that the shutdown zone is 

clear must be made during a period of 

good visibility (i.e., the entire shutdown 

zone and surrounding waters must be 

visible to the naked eye). 

Soft-Start Procedures 

Soft-start procedures are used to 

provide additional protection to marine 

mammals by providing warning and/or 

giving marine mammals a chance to 

leave the area prior to the hammer 

operating at full capacity. For impact 

pile driving, contractors would be 

required to provide an initial set of three 

strikes from the hammer at reduced 

energy, followed by a 30-second waiting 

period, then two subsequent reducedenergy strike sets. Soft start would 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. 

Bubble Curtain 

A bubble curtain must be employed 

during all impact pile installation of 

steel piles less than 24 inches in 

diameter to interrupt the acoustic 

pressure and reduce impact on marine 

mammals. Impact pile driving will not 

be allowed for 36-inch steel shell piles. 

The bubble curtain must distribute air 

bubbles around 100 percent of the piling 

circumference for the full depth of the 

water column. The lowest bubble ring 

must be in contact with the mudline for 

the full circumference of the ring. The 

weights attached to the bottom ring 

must ensure 100 percent substrate 

contact. No parts of the ring or other 

objects may prevent full substrate 

contact. Air flow to the bubblers must 

be balanced around the circumference 

of the pile. 

Based on our evaluation of the 

applicant’s proposed measures, NMFS 

has preliminarily determined that the 

proposed mitigation measures provide 

the means of 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 while conducting the activities. 

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 

activity; 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 

conditions in this section and the IHA. 

Marine mammal monitoring during pile 

driving activities would be conducted 

by PSO’s meeting NMFS’ standards and 

in a manner consistent with the 

following: 

• PSOs must be independent of the 

activity contractor (for example, 

employed by a subcontractor) and have 

no other assigned tasks during 

monitoring periods; 

• At least one PSO would 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 

is required, a lead observer or 

monitoring coordinator would be 

designated. The lead observer would be 

required to have prior experience 

working as a marine mammal observer 

during construction. 

• PSOs will submit PSO resumes for 

approval by NMFS 30 days prior to the 

onset of pile driving. 

• PSOs must be approved by NMFS 

prior to beginning any activity subject to 

the IHA. 

PSOs should 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. 

PG&E would have between one and 

three PSOs on site at all times during 

pile driving activities. One PSO would 

be designated as the Lead PSO and 

would receive updates from other PSOs. 

The Lead PSO would be stationed at the 

active pile driving rig or at the best 

vantage point practicable to monitor the 

shutdown zones and implement 

shutdown and delay procedures. The 

other PSOs would be stationed at the 

best vantage points practicable to 

observe the monitoring zones. Exact 

locations would be determined in the 

field based on the pile driving site, field 

conditions, and in coordination with 

contractors, but may include docks, 


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barges, and tower structures. PSOs 

would be equipped with high quality 

binoculars or spotting scopes for 

monitoring and radios and cell phones 

for maintaining contact with other 

observers and work crew. Monitoring 

would be conducted 30 minutes before, 

during, and 30 minutes after all in-water 

construction activities. PSOs would 

record all incidents of marine mammal 

occurrence, regardless of distance from 

activity, and would 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 

equipment is no more than 30 minutes. 

Data Collection 

PSOs would use approved data forms 

to record the following information: 

• Dates and times (beginning and 

end) of all marine mammal monitoring. 

• PSO locations during 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). 

• Weather parameters and water 

conditions. 

• 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. 

• Distance and bearings of each 

marine mammal observed to the pile 

being driven or removed. 

• Description of marine mammal 

behavior patterns, including direction of 

travel. 

• Age and sex class, if possible, of all 

marine mammals observed. 

• Detailed information about 

implementation of any mitigation 

triggered (such as shutdowns and 

delays), a description of specific actions 

that ensued, and resulting behavior of 

the animal if any. 

Reporting 

PG&E must submit a draft marine 

mammal monitoring report to NMFS 

within 90 days after the completion of 

pile driving activities, or 60 days prior 

to the requested issuance of any future 

IHAs for the project, or other projects at 

the same location, whichever comes 

first. A final report must be prepared 

and submitted within 30 calendar days 

following receipt of any NMFS 

comments on the draft report. If no 

comments are received from NMFS 

within 30 calendar days of receipt of the 

draft report, the report shall be 

considered final. The marine mammal 

report would include an overall 

description of work completed, a 

narrative regarding marine mammal 

sightings, and associated PSO data 

sheets and/or raw sighting data. 

Specifically, the report would include: 

• Dates and times (beginning and 

end) of all marine mammal monitoring; 

• Construction activities occurring 

during each daily observation period 

including: (a) the number and types of 

piles driven and the method; and (b) 

total duration of driving time for each 

pile (vibratory driving) and number of 

strikes for each pile (impact driving). 

• PSO locations during marine 

mammal monitoring; 

• Environmental conditions during 

monitoring periods (at beginning and 

end of PSO shift and whenever 

conditions change significantly), 

including Beaufort sea state and any 

other relevant weather conditions 

including cloud cover, fog, sun glare, 

and overall visibility to the horizon, and 

estimated observable distance; 

• For each observation of a marine 

mammal the following must be 

recorded: (a) Name of PSO who sighted 

the animal(s) and PSO location and 

activity at time of sighting; (b) time of 

sighting; (c) identification of the 

animal(s) (e.g., genus/species, lowest 

possible taxonomic level, or 

unidentified), PSO confidence in 

identification, and the composition of 

the group if there is a mix of species; (d) 

distance and location of each observed 

marine mammal relative to pile being 

driven or removed for each sighting; (e) 

estimated number of animals (min/max/ 

best estimate); (f) estimated number of 

animals by cohort (adults, juveniles, 

neonates, group composition, etc.); (g) 

animal’s closest point of approach and 

estimated time spent within the 

harassment zone; (h) description of any 

marine mammal behavioral observations 

(e.g., observed behaviors such as feeding 

or traveling), including an assessment of 

behavioral responses thought to have 

resulted from the activity (e.g., no 

response or changes in behavioral state 

such as ceasing feeding, changing 

direction, flushing, or breaching); 

• Number of marine mammals 

detected within the harassment zones, 

by species; and 

• Detailed information about 

implementation of any mitigation (e.g., 

shutdowns and delays), a description of 

specific actions that ensued, and 

resulting changes in behavior of the 

animal(s), if any. 

Reporting Injured or Dead Marine 

Mammals 

In the event that personnel involved 

in the construction activities discover 

an injured or dead marine mammal, 

PG&E would report the incident to the 

Office of Protected Resources (OPR) 

(PR.ITP.MonitoringReports@noaa.gov), 

NMFS and to the West Coast regional 

stranding network (866–767–6114) as 

soon as feasible. If the death or injury 

was clearly caused by the specified 

activity, PG&E would 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 

IHAs. PG&E would not resume their 

activities until notified by NMFS. The 

report would include the following: 

• 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 impacts or responses (e.g., 

intensity, duration), the context of any 

impacts or responses (e.g., critical 

reproductive time or location, foraging 

impacts affecting energetics), 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’ implementing 

regulations (54 FR 40338; September 29, 

1989), the impacts from other past and 

ongoing anthropogenic activities are 


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incorporated into this analysis via their 

impacts on the 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). 

To avoid repetition, the discussion of 

our analysis applies to all the species 

listed in table 3, given that the 

anticipated effects of this activity on 

these different marine mammal stocks 

are expected to be similar. There is little 

information about the nature or severity 

of the impacts, or the size, status, or 

structure of any of these species or 

stocks that would lead to a different 

analysis for this activity. 

Level A harassment is extremely 

unlikely given the small size of the 

Level A harassment isopleths and the 

required mitigation measures designed 

to minimize the possibility of injury to 

marine mammals. No serious injury or 

mortality is anticipated given the nature 

of the activity. 

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 impact and 

vibratory pile driving activities. 

Potential takes could occur if 

individuals move into the ensonified 

zones when these activities are 

underway. 

The takes by Level B harassment 

would be due to potential behavioral 

disturbances. The potential for 

harassment is minimized through 

construction methods and the 

implementation of planned mitigation 

strategies (see Proposed Mitigation 

section). 

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 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 over approximately 50 days 

during a span of 5 months, any 

harassment would be temporary. There 

are no other areas or times of known 

biological importance for any of the 

affected species. 

Take would occur within a limited, 

confined area of each stock’s range. 

Further, the amount of take authorized 

is extremely small when compared to 

stock abundance. 

No marine mammal stocks for which 

incidental take authorization are listed 

as threatened or endangered under the 

ESA. Only one stock, the Eastern North 

Pacific Stock of the northern fur seal, is 

listed as depleted under the MMPA. 

However, we do not expect the 

proposed authorizations in this action to 

affect the stock. No injury or mortality 

is proposed for authorization, take by 

Level B harassment is limited (five takes 

over the duration of the project), and the 

proposed action should have no effect 

on the reproduction of this species. In 

addition, the five authorized takes for 

the northern fur seal include both the 

depleted Eastern North Pacific Stock 

and the California stock, which is not 

depleted. 

The relatively low marine mammal 

occurrences in the area, shutdown 

zones, and planned monitoring make 

injury takes of marine mammals 

unlikely. The shutdown zones would be 

thoroughly monitored before the pile 

driving activities begin, and activities 

would be postponed if a marine 

mammal is sighted within the shutdown 

zone. There is a high likelihood that 

marine mammals would be detected by 

trained observers under environmental 

conditions described for the project. 

Limiting construction activities to 

daylight hours would also increase 

detectability of marine mammals in the 

area. Therefore, the mitigation and 

monitoring measures are expected to 

eliminate the potential for injury and 

Level A harassment as well as reduce 

the amount and intensity of Level B 

behavioral harassment. Furthermore, the 

pile driving activities analyzed here are 

similar to, or less impactful than, 

numerous construction activities 

conducted in other similar locations 

which have occurred with no reported 

injuries or mortality to marine 

mammals, and no known long-term 

adverse consequences from behavioral 

harassment. 

The project is not expected to have 

significant adverse effects on marine 

mammal habitat. There are no known 

Biologically Important Areas (BIAs) or 

ESA-designated critical habitat within 

the project area, and the activities 

would not permanently modify existing 

marine mammal habitat. 

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 any of 

the species or stocks through effects on 

annual rates of recruitment or survival: 

• No serious injury, mortality, or 

Level A harassment is anticipated or 

proposed for authorization. 

• The specified activities and 

associated ensonified areas are very 

small relative to the overall habitat 

ranges of all species; 

• The project area does not overlap 

known BIAs or ESA-designated critical 

habitat; 

• The lack of anticipated significant 

or long-term effects or marine mammal 

habitat; and 

• The presumed efficacy of the 

mitigation measures in reducing the 

effects of the specified activity. 

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 previously, only take of 

small numbers of marine mammals may 

be authorized under sections 

101(a)(5)(A) and (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 

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 has 

authorized is below one-third of the 

estimated stock abundances for stocks 

(See table 9). These are all likely 

conservative estimates 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 would be 

taken relative to the population size of 

the affected species or stocks. 


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82856 Federal Register / Vol. 88, No. 226 / Monday, November 27, 2023 / Notices 

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 Endangered 

Species Act of 1973 (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 

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 Pacific Gas & Electric for 

conducting pile driving activities in San 

Francisco Bay from April 1, 2024 to 

March 31, 2025, 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/national/ 

marine-mammal-protection/incidentaltake-authorizations-constructionactivities. 

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 construction 

project. We also request 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, 1-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 the renewal IHA expiration date 

cannot extend beyond 1 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). 

(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. 

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: November 20, 2023. 

Catherine Marzin, 

Acting Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2023–26012 Filed 11–24–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF DEFENSE 

Department of the Army 

Performance Review Board 

Membership 

AGENCY: Department of the Army, DoD. 

ACTION: Notice. 

SUMMARY: Notice is given of the names 

of members of a Performance Review 

Board for the Department of the Army. 

DATES: Applicable November 13, 2023. 

FOR FURTHER INFORMATION CONTACT: 

Barbara Smith, Civilian Senior Leader 

Management Office, 111 Army 

Pentagon, Washington, DC 20310–0111, 

email: Barbara.M.Smith.civ@army.mil 

or phone: (703) 693–1126. 

SUPPLEMENTARY INFORMATION: Section 

4314(c)(1) through (5) of title 5, U.S.C., 

requires each agency to establish, in 

accordance with regulations, one or 

more Senior Executive Service 

performance review boards. The boards 

shall review and evaluate the initial 

appraisal of senior executives’ 

performance by supervisors and make 

recommendations to the appointing 

authority or rating official relative to the 

performance of these executives. 

The Department of the Army 

Performance Review Board will be 

composed of a subset of the following 

individuals: 

1. Ms. Elizabeth J Ahlersmeyer O’Kane, 

Senior Security Advisor, Office of 

the Deputy Chief of Staff, G–2 

2. Dr. Christine T Altendorf, Director of 

Military Programs, Military 

Programs, U.S. Army Corps of 

Engineers 

3. Mr. Stephen D Austin, Assistant Chief 

of the Army Reserve, Office of the 

Chief of the Army Reserve 

4. Mr. Mark F Averill, Administrative 

Assistant to the Secretary of the 

Army, Office of the Administrative 

Assistant to the Secretary of the 

Army 

5. Mr. Young J Bang, Principal Deputy 

Assistant Secretary of the Army 

(Acquisitions, Logistics and 

Technology), Office of the Assistant 

Secretary of the Army (Acquisition, 

Logistics, and Technology) 

6. LTG Maria B Barrett, Commanding 

General, U.S. Army Cyber 

Command 

7. Mr. Stephen G Barth, Deputy Chief of 

Staff, G–8, U.S. Army Training and 

Doctrine Command 

8. Mr. Peter Bechtel, Deputy G–3/5/7, 

Deputy Chief of Staff, G–3/5/7 

9. BG Christine A Beeler, Commanding 

General, U.S. Army Contracting 

Command, U.S. Army Materiel 

Command 

10. Ms. Pamela I Blechinger, Director, 

The Research and Analysis Center, 

The Research and Analysis Center, 

U.S. Army Futures Command 

11. Ms. Yvette K W Bourcicot, Principal 

Deputy Assistant Secretary of the 

Army (Manpower and Reserve 

Affairs), Office of the Assistant 

Secretary of the Army (Manpower 

and Reserve Affairs) 

12. Mr. John M Bradsher, Director, 

Operations and Integration, Office 

of the Deputy Chief of Staff, G–2 


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