Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Columbia East Lateral XPRESS Project, 61530-61548 [2023-19310]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 88, Number 172 (Thursday, September 7, 2023)]
[Notices]
[Pages 61530-61548]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-19310]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD182]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Columbia East Lateral XPRESS 
Project

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.

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SUMMARY: NMFS has received a request from TC Energy Columbia Gulf 
Transmission, LLC for authorization to take marine mammals incidental 
to the East Lateral XPRESS Project in Barataria Bay, Louisiana. 
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, one-year renewal that could be issued under certain 
circumstances and if all requirements are met, as described in Request 
for Public Comments at the end of this notice. NMFS will consider 
public comments prior to making any final decision on the issuance of 
the requested MMPA authorization and agency responses will be 
summarized in the final notice of our decision.

DATES: Comments and information must be received no later than October 
10, 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 
[email protected].
    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-authorizations-oil-and-gas 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-authorizations-oil-and-gas. In case 
of problems accessing these documents, please call the contact listed 
below.

FOR FURTHER INFORMATION CONTACT: Steven Tucker, 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

[[Page 61531]]

practicable adverse impact'' on the affected species or stocks and 
their habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance, and on the availability of 
the species or stocks for taking for certain subsistence uses (referred 
to in shorthand as ``mitigation''); and requirements pertaining to the 
mitigation, monitoring and reporting of the takings are set forth. The 
definitions of all applicable MMPA statutory terms cited above are 
included in the relevant sections below.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) of the Companion Manual for NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the issuance of the proposed IHA 
qualifies to be categorically excluded from further NEPA review. We 
will review all comments submitted in response to this notice prior to 
concluding our NEPA process or making a final decision on the IHA 
request.

Summary of Request

    On March 3, 2023, NMFS received a request from TC Energy/Columbia 
Gulf Transmission, LLC (Columbia Gulf) for an IHA to take marine 
mammals incidental to construction activities that include pile driving 
to install: (1) a point of delivery metering station (or, POD), and (2) 
a tie-in facility (or, TIF) in Barataria Bay. The project is intended 
to provide feed fuel for on-shore Liquefied Natural Gas (LNG) 
compressor stations. The application was deemed adequate and complete 
on June 5, 2023. Columbia Gulf's request is for take of bottlenose 
dolphin (Tursiops truncatus, Barataria Bay Estuarine System stock or, 
BBES) by Level B harassment only. Neither Columbia Gulf nor NMFS 
expects serious injury or mortality to result from this activity and, 
therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    Columbia Gulf Transmission, LLC, a wholly-owned subsidiary of TC 
Energy Corporation, proposes to construct two new compressor stations, 
a new meter station, approximately 8 miles (13 kilometers) of new 30-
inch diameter natural gas pipeline lateral, two new mainline valves, a 
tie-in facility, launcher and receiver facilities, and other auxiliary 
appurtenant facilities all located in St. Mary, Lafourche, Jefferson, 
and Plaquemines parishes, Louisiana (collectively referred to as 
``Project''). A summary of all construction activities necessary to 
complete the all elements of the project are shown in Table 1.

Table 1--All Elements of the Project. Bolded Elements Include In-Water Activities That May Result in the Take of
                                                 Marine Mammals
----------------------------------------------------------------------------------------------------------------
                                                          Pipeline milepost
             Facility                     Parish              location                    Description
----------------------------------------------------------------------------------------------------------------
                                               Pipeline Facilities
----------------------------------------------------------------------------------------------------------------
30-inch Pipeline Lateral.........  Jefferson..........             0.00-2.47  Install approximately 13.1
                                                                               kilometers (8.14) miles of new 30-
                                                                               inch-diameter pipeline lateral.
                                   Plaquemines........             2.47-8.14  ..................................
----------------------------------------------------------------------------------------------------------------
                                             Aboveground Facilities
----------------------------------------------------------------------------------------------------------------
Centerville Compressor Station...  St. Mary...........        \a\ 66.50, \b\  Construct a new gas-fired
                                                            66.70, \c\ 67.00   compressor station with a 23,470
                                                                               hp compressor unit, which will
                                                                               interconnect with Columbia Gulf's
                                                                               existing EL-100, EL-200, and EL-
                                                                               300 pipelines.
Golden Meadow Compressor Station.  Lafourche..........            \c\ 149.50  Construct a new gas-fired
                                                                               compressor station with a 23,470
                                                                               hp compressor unit, which will
                                                                               interconnect with Columbia Gulf's
                                                                               existing EL-300 pipeline.
Point of Delivery Meter Station..  Plaquemines........                  8.14  Construct one point of delivery
                                                                               meter station at the terminus of
                                                                               the new 30-inch pipeline lateral
                                                                               on an existing platform shared
                                                                               with Venture Global Gator
                                                                               Express, LLC. A 30-inch pig
                                                                               receiver will also be installed
                                                                               at the POD Meter Station.
Tie-in Facility..................  Jefferson..........                  0.00  Install a new tie-in facility
                                                                               situated on a new platform at the
                                                                               intersection of the new 30-inch
                                                                               pipeline and Columbia Gulf's
                                                                               existing EL-300 pipeline. A 30-
                                                                               inch pig launcher will also be
                                                                               Installed at the Tie-in Facility.
Valves and Other Ancillary         Jefferson..........        0.00, \c\ 1.71  Install one new 30-inch mainline
 Facilities.                                                                   valve assembly on the new 30-inch
                                                                               pipeline lateral and one new 24-
                                                                               inch mainline valve assembly
                                                                               Columbia Gulf's existing EL-300
                                                                               pipeline. Both mainline valve
                                                                               assemblies will be situated on
                                                                               the new Tie-in Facility platform.
----------------------------------------------------------------------------------------------------------------
\a\ Milepost is associated with Columbia Gulf's existing EL-100 pipeline.
\b\ Milepost is associated with Columbia Gulf's existing EL-200 pipeline.
\c\ Milepost is associated with Columbia Gulf's existing EL-300 pipeline.

    The work necessary to complete construction of the project would 
temporarily impact 2.79 acres, permanently alter .02 acres and include 
in-water activity that may result in take of marine mammals in 
Barataria Bay. Specifically, in order to provide fuel supply services 
to onshore LNG compressor stations, Columbia Gulf proposes pile driving 
to construct a new Point of Delivery Meter Station on an existing 
platform and a new Tie-in

[[Page 61532]]

Facility at the terminus a new 30-inch lateral pipeline. Project 
activities include installation, by impact hammer, of 20 18-inch 
concrete piles and 104 36-inch spun cast piles. The new POD Meter 
Station will include the installation of three 16-inch meter runs and 
related facilities. The new POD Meter Station will be constructed at 
the site of an existing platform, and construction will require the 
installation of four new 18-inch square concrete piles to protect a 30-
inch- diameter riser. Pipelines will be installed by jetting and 
dredging with displaced sediment precipitating back to the substrate or 
being side-cast adjacent to the trench, respectively.
    The new Tie-in Facility will be situated on a new 180 foot (55 
meter) long by 80 foot (24.3 meter) wide platform supported by 104 36-
inch-diameter spun cast and 4 18-inch-diameter concrete piles. Two 24-
inch-diameter and one 30-inch-diameter risers will be protected by 12 
a8-inch diameter concrete piles. The Tie-in Facility would include a 
boat landing measuring 10 foot (3 meter) long by 10 foot (3 meter) 
wide, that will be used for maintenance and servicing of the platform.
    These activities would be supported by eight vessels using existing 
public barge channels and waterways during an estimated 16 barge trips 
per week. Because vessels will be in transit, exposure to ship noise 
will be temporary, relatively brief and will occur in a predictable 
manner, producing sound at a relatively low level and consistent with 
use of the waterway and other activity in the area. In order to reduce 
the number barge transits during construction, Columbia Gulf intends to 
station one or more barges onsite for hoteling of personnel.

Dates and Duration

    Columbia Gulf proposes to start construction in January, 2024 in 
order to meet a planned in-service date of April, 2025. Pile driving 
within Barataria Bay is anticipated to occur within a 3 month period 
from January, 2025 to March, 2025. Pile driving activity will be 
intermittent, conducted in accordance with project phasing 
requirements, and as such will not be continuous throughout the 3-month 
period. Pile driving activities would take place from 7 a.m. to 7 p.m. 
(adjusted as appropriate to conduct work during daylight hours), and 
could occur on any day of the week for about 25 days (five piles per 
day).

Specific Geographic Region

    Barataria Bay is a shallow estuarine system, and is categorized as 
an open bay habitat with a mean depth of approximately 2.0 meters (U.S. 
Environmental Protection Agency, 1999; Conner and Day, 1987). Archival 
data collected at NOAA's St. Mary's Point station indicate a mean tidal 
range of 0.97 feet, with Mean High-High Water reference elevation of 
.47' and Mean Low-Low Water reference elevation of -2.32. The bay has 
two fronting barrier islands (Grand Isle and Grand Terre) that separate 
it from the rest of the Gulf of Mexico and that also inhibit underwater 
sound transmission from portions of the Bay to the coastal waters of 
the Gulf of Mexico.
BILLING CODE 3510-22-P

[[Page 61533]]

[GRAPHIC] [TIFF OMITTED] TN07SE23.012

BILLING CODE 3510-22-C
    Barataria Bay is bordered by tidal salt marshes and is connected to 
a series of passes (i.e., Caminada Pass, Barataria Pass, Pass Abel, and 
Quatre Bayou Pass) which, in turn, provide hydrologic connection to the 
waters of the Gulf of Mexico (NMFS, 2023a; Conner and Day, 1987). To 
the east, Barataria Bay is bounded by levees surrounding the 
Mississippi River and to the west it is bordered by Bayou Lafourche 
(Birdsong, 2004). The waters of Barataria Bay are turbid with lower 
salinity level (including the presence of freshwater lakes) in northern 
reaches. Higher salinity levels prevail in the southern portion of the 
bay due to tidally influenced exchange with Gulf coastal waters (NMFS, 
2023a). As a result, measured salinity concentrations in

[[Page 61534]]

Barataria Bay can vary ranging from 6 to 22 parts per trillion, 
depending on the sampling location.

Detailed Description of the Specified Activity

    Columbia Gulf proposes to construct a POD Meter Station on an 
existing platform along with the new receiver at the terminus of a new 
30-inch pipeline lateral within Barataria Bay. The new POD Meter 
Station requires installation of three 16-inch meter runs and related 
facilities. The new POD Meter Station is proposed for construction on 
an existing platform, and requires the installation of four 18-inch 
square concrete piles in order to protect a 30-inch-diameter riser.
    In addition to shore side construction and installation of the POD 
meter station, Columbia Gulf proposes to construct a new Tie-in 
Facility at the intersection of the new 30-inch pipeline lateral and 
Columbia Gulf's existing EL-300 pipeline. With the exception of a 
portion of two new 24-inch-diameter risers and one new 30-inch-diameter 
riser which will be underwater, the Tie-in Facility will be constructed 
on a new 180 foot (55 meter) long by 80 foot (24.3 meter) wide platform 
supported by 104 36-inch-diameter spun cast and 4 18-inch-diameter 
concrete piles. Twelve 18-inch-diameter concrete piles will be 
installed to protect the 2 24-inch-diameter and 1 30-inch-diameter 
risers. The new platform will also be equipped with a boat landing, 
which will measure 10 feet (3 meters) long by 10 feet (3 meters) wide 
and will enable maintenance activities during operation of the Project.
    Of the activities described in the application, noise from pile-
driving is the only activity expected to result in level B harassment 
of bottlenose dolphins, and the implications of pile driving are 
discussed in greater detail below. The Piles and method of installation 
are presented in Table 2, below.

                                                        TABLE 2--Proposed Pile Driving Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Number of       Proposed pile      Proxy pile for    Impact strikes                    Strikes per       Days of
            Location                   piles         diameter/type       calculations        per pile      Piles per day        day        installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Tie-in Facility.................             104  36'' Spun Cast      36'' Concrete                4,800               5          24,000              24
                                                   Concrete Piles.     (round, hollow).
Tie-in Facility.................              16  18'' Concrete
                                                   (round).
Point of Delivery Platform......               4  18'' Concrete                                                                                        1
                                                   (square).
                                 -----------------------------------------------------------------------------------------------------------------------
    Total.......................             120                                                                                                      25
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the Barataria Bay Estuarine Stock (BBES) 
of bottlenose dolphins. NMFS fully considered all of this information, 
including relevant citations which may be included here, and we refer 
the reader to these materials instead of reprinting the information. 
Additional information regarding population estimates and potential 
threats for the Barataria Bay Estuarine System stock of bottlenose 
dolphins, can be found in NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more information about this species in 
general (e.g., physical and behavioral descriptions) may be found on 
NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Take of BBES bottlenose dolphins may occur incidental to the 
specified activities described in the request for authorization. 
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 is provided in Table 3. 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.
    The BBES abundance estimate presented in this document represents 
the estimated total number of individuals within study and survey areas 
in Barataria Bay. BBES are one of several estuarine stocks fringing the 
northern Gulf of Mexico, and Barataria Bay is considered a Biologically 
Important Area year-round for the Small and Resident Population. In 
addition to Barataria Bay itself, individual BBES dolphins may be found 
in Caminada Bay, Bay Coquette, and Gulf coastal waters extending 1 
kilometer (km) from the shoreline (NMFS, 2023a).
    The BBES stock was first designated in 1995 and is regarded as 
distinct from populations in adjacent Gulf coastal waters based on 
genetics, reproductive seasonality and direct observations. BBES 
bottlenose dolphins are present throughout Bay year-round including in 
the vicinity of the proposed construction site. Accordingly, when 
estimating take and weighing potential impacts, BBES dolphin abundance, 
density and distribution is presumed to be consistent throughout the 
construction period. No additional assumptions or qualitative 
adjustments were made based on seasonality. The values presented in 
Table 2 are the most recent available at the time of publication 
(including the draft 2022 SARs) and are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

[[Page 61535]]



                                           Table 3--Marine Mammals Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                    Stock
                                                                                                                  abundance
                                                                                                                 (CV, Nmin,
             Common name                  Scientific name               Stock              ESA/MMPA status;      most recent       PBR       Annual M/SI
                                                                                          strategic (Y/N) \2\     abundance                      \4\
                                                                                                                 survey) \3\
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bottlenose Dolphin..................  Tursiops truncatus.....  Barataria Bay Estuarine  Y--Strategic..........        2,071            18           160
                                                                Stock.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, vessel strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A
  CV associated with estimated mortality due to commercial fisheries is presented in some cases.

    As described above, animals from the BBES stock of bottlenose 
dolphins temporarily and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. While other marine 
mammal species may occur in offshore waters of the Gulf of Mexico, the 
characteristics of Barataria Bay make transits or sustained presence in 
the area affected by the specified activity exceedingly unlikely and as 
a result take is not expected to occur. Given take of other marine 
mammal species is not expected, they are not discussed further.
    The BBES stock has been affected by three declared unusual 
mortality events, all of which are now closed. The first spanned 
January through May of 1990 (in which 344 individuals became stranded), 
the second from March 2010 to July 2014 (which included stranding 
before, during, and after the Deepwater Horizon (DWH) oil spill), and 
the third from February to November of 2019 and was found to be a 
result of freshwater discharge from rivers (NMFS, 2023a).
    Research conducted after the DWH oil spill found that the BBES 
dolphins suffered a wide range of effects, including impaired 
reproduction, respiratory illness, other diseases, and death. These and 
other physiological and environmental challenges that followed the 
spill impacted individual animals' ability to thrive and diminished the 
health of the stock. In Barataria Bay alone, it is estimated that 45 
percent of the common bottlenose dolphin population was lost following 
the spill (Schwacke et al., 2021).
    NMFS regards BBES dolphins to be a strategic stock. Insufficient 
data exists to assess population trends for the stock. However, impacts 
examined in the course of past Unusual Mortality Events, including 
impacts from the DWH oil spill and changes in habitat characteristics, 
coupled with an estimated PBR rate greater than 10 percent support the 
Service's finding that the stock is strategic.
    LeBreque et al. (2015) identified a small and resident population 
Biologically Important Area for bottlenose dolphins in the Caminada Bay 
and Southwest Barataria Bay area, indicating that the range of this 
small population is limited to this area.

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 low-frequency 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         7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans (dolphins,      150 Hz to 160 kHz.
 toothed whales, beaked whales, bottlenose
 whales).
High-frequency (HF) cetaceans..............  275 Hz to 160 kHz.
(true porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus cruciger &
 L. australis).
Phocid pinnipeds (PW) (underwater) (true     50 Hz to 86 kHz.
 seals).
Otariid pinnipeds (OW) (underwater) (sea     60 Hz to 39 kHz.
 lions and fur seals).
------------------------------------------------------------------------
* 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).


[[Page 61536]]

    The pinniped hearing group was modified from Southall et al. (2007) 
on the basis of data indicating that phocid species have consistently 
demonstrated an extended frequency range of hearing compared to 
otariids, especially in the higher frequency range (Hemil[auml] et al., 
2006; Kastelein et al., 2009; Reichmuth et al., 2013). This division 
between phocid and otariid pinnipeds is now reflected in the updated 
hearing groups proposed in Southall et al. (2019).
    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 
presents the number of individual animals 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 activity 
are expected to potentially occur from impact pile driving. The effects 
of underwater noise from Columbia Gulf's activities have the potential 
to result in Level B harassment of marine mammals in the action area. 
These activities are not expected to cause serious injury or mortality, 
and no take by Level A harassment is proposed.

Background on Sound

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used relevant to 
the specified activity and to a discussion of the potential effects of 
the specified activity on marine mammals found later in this document. 
For general information on sound and its interaction with the marine 
environment, please see, Erbe and Thomas (2022); Au and Hastings 
(2008); Richardson et al. (1995); Urick (1983); as well as the 
Discovery of Sound in the Sea (DOSITS) website at https://dosits.org/.
    Sound is a vibration that travels as an acoustic wave through a 
medium such as a gas, liquid or solid. Sound waves alternately compress 
and decompress the medium as the wave travels. In water, sound waves 
radiate in a manner similar to ripples on the surface of a pond and may 
be either directed in a beam (narrow beam or directional sources) or 
sound may radiate in all directions (omnidirectional sources), as is 
the case for sound produced by the pile driving activity considered 
here. The compressions and decompressions associated with sound waves 
are detected as changes in pressure by marine mammals and human-made 
sound receptors such as hydrophones.
    Sound travels more efficiently in water than almost any other form 
of energy, making the use of sound as a primary sensory modality ideal 
for inhabitants of the aquatic environment. In seawater, sound travels 
at roughly 1,500 meters per second (m/s). In air, sound waves travel 
much more slowly at about 340 m/s. However, the speed of sound in water 
can vary by a small amount based on characteristics of the transmission 
medium such as temperature and salinity.
    The basic characteristics of a sound wave are frequency, 
wavelength, velocity, and amplitude. Frequency is the number of 
pressure waves that pass by a reference point per unit of time and is 
measured in hertz (Hz) or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly with 
distance, except in certain cases in shallower water. The amplitude of 
a sound pressure wave is related to the subjective ``loudness'' of a 
sound and is typically expressed in decibels (dB), which are a relative 
unit of measurement that is used to express the ratio of one value of a 
power or pressure to another. A sound pressure level (SPL) in dB is 
described as the ratio between a measured pressure and a reference 
pressure, and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. For example, a 10-dB increase is a 
ten-fold increase in acoustic power. A 20-dB increase is then a 100-
fold increase in power and a 30-dB increase is a 1000-fold increase in 
power. However, a ten-fold increase in acoustic power does not mean 
that the sound is perceived as being 10 times louder. The dB is a 
relative unit comparing two pressures; therefore, a reference pressure 
must always be indicated. For underwater sound, this is 1 microPascal 
([mu]Pa). For in-air sound, the reference pressure is 20 microPascal 
([mu]Pa). The amplitude of a sound can be presented in various ways; 
however, NMFS typically considers three metrics: sound exposure level 
(SEL), root-mean-square (RMS) SPL, and peak SPL (defined below). The 
source level represents the SPL referenced at a standard distance from 
the source (Richardson et al., 1995; American National Standards 
Institute (ANSI), 2013)(typically 1 m) (Richardson et al., 1995; 
American National Standards Institute (ANSI), 2013), while the received 
level is the SPL at the receiver's position. For pile driving 
activities, the SPL is typically referenced at 10 m.
    SEL (represented as dB referenced to 1 micropascal squared second 
(re 1 [mu]Pa\2\-s)) represents the total energy in a stated frequency 
band over a stated time interval or event, and considers both intensity 
and duration of exposure. The per-pulse SEL (e.g., single strike or 
single shot SEL) is calculated over the time window containing the 
entire pulse (i.e., 100 percent of the acoustic energy). SEL can also 
be a cumulative metric; it can be accumulated over a single pulse (for 
pile driving this is the same as single-strike SEL, above; 
SELss), or calculated over periods containing multiple 
pulses (SELcum). Cumulative SEL (SELcum) 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. The SEL metric is useful because it 
allows sound exposures of different durations to be related to one 
another in terms of total acoustic energy. The duration of a sound 
event and the number of pulses, however, should be specified as there 
is no accepted standard duration over which the summation of energy is 
measured.
    RMS SPL is equal to ten times the logarithm (base 10) of the ratio 
of the mean-square sound pressure to the specified reference value, and 
given in units of dB (International Organization for Standardization 
(ISO), 2017). RMS is calculated by squaring all of the sound 
amplitudes, averaging the squares, and then taking the square root of 
the average (Urick, 1983). RMS accounts for both positive and negative 
values; squaring the pressures makes all values positive so that they 
may be accounted for in the summation of pressure levels (Hastings and 
Popper, 2005). This measurement is often used in the context of 
discussing behavioral effects, in part because behavioral effects, 
which often result from auditory cues, may be better expressed through

[[Page 61537]]

averaged units than by peak SPL. For impulsive sounds, RMS is 
calculated by the portion of the waveform containing 90 percent of the 
sound energy from the impulsive event (Madsen, 2005).
    Peak SPL (also referred to as zero-to-peak sound pressure or 0-pk) 
is the maximum instantaneous sound pressure measurable in the water, 
which can arise from a positive or negative sound pressure, during a 
specified time, for a specific frequency range at a specified distance 
from the source, and is represented in the same units as the RMS sound 
pressure (ISO, 2017). Along with SEL, this metric is used in evaluating 
the potential for permanent threshold shift (PTS) and temporary 
threshold shift (TTS) associated with impulsive sound sources.
    Sounds are also characterized by their temporal components. 
Continuous sounds are those whose sound pressure level remains above 
that of the ambient or background sound with negligibly small 
fluctuations in level (ANSI, 2005) while intermittent sounds are 
defined as sounds with interrupted levels of low or no sound (National 
Institute for Occupational Safety and Health (NIOSH), 1998). A key 
distinction between continuous and intermittent sound sources is that 
intermittent sounds have a more regular (predictable) pattern of bursts 
of sounds and silent periods (i.e., duty cycle), which continuous 
sounds do not.
    Sounds may be either impulsive or non-impulsive (defined below). 
The distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to noise-induced hearing loss (e.g., Ward, 1997 in Southall et 
al., 2007). Please see NMFS (2018) and Southall et al. (2007; 2019) for 
an in-depth discussion of these concepts.
    Impulsive sound sources (e.g., sonic booms, seismic airgun shots, 
impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986; NIOSH, 1998; ANSI, 2005) and occur either as isolated 
events or repeated in some succession. Impulsive sounds are all 
characterized by a relatively rapid rise from ambient pressure to a 
maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features. Impulsive 
sounds are intermittent in nature. The duration of such sounds, as 
received at a distance, can be greatly extended in a highly reverberant 
environment.
    Non-impulsive sounds can be tonal, narrowband, or broadband, brief 
or prolonged, and may be either continuous or non-continuous (ANSI, 
1995; NIOSH, 1998). Some of these non-impulsive sounds can be transient 
signals of short duration but without the essential properties of 
impulses (e.g., rapid rise time). Examples of non-impulsive sounds 
include those produced by vessels, aircraft, machinery operations such 
as drilling (including DTH systems) or dredging, vibratory pile 
driving, and active sonar systems.
    Even in the absence of sound from the specified activity, the 
underwater environment is characterized by sounds from both natural and 
anthropogenic sound sources. Ambient sound is defined as a composite of 
naturally-occurring (i.e. non-anthropogenic) sound from many sources 
both near and far (ANSI, 1995). Background sound is similar, but 
includes all sounds, including anthropogenic sounds, minus the sound 
produced by the proposed (NMFS, 2012; 2016). The sound level of a 
region is defined by the total acoustical energy being generated by 
known and unknown sources. These sources may include physical (e.g., 
wind and waves, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic (e.g., vessels, dredging, construction) sound. A number 
of sources contribute to background and ambient sound, including wind 
and waves, which are a main source of naturally occurring ambient sound 
for frequencies between 200 Hz and 50 kilohertz (kHz) (Mitson, 1995). 
In general, background and ambient sound levels tend to increase with 
increasing wind speed and wave height. Precipitation can become an 
important component of total sound at frequencies above 500 Hz, and 
possibly down to 100 Hz during quiet times. Marine mammals can 
contribute significantly to background and ambient sound levels, as can 
some fish and snapping shrimp. The frequency band for biological 
contributions is from approximately 12 Hz to over 100 kHz. Sources of 
background sound related to human activity include transportation 
(surface vessels), dredging and construction, oil and gas drilling and 
production, geophysical surveys, sonar, and explosions. Vessel noise 
typically dominates the total background sound for frequencies between 
20 and 300 Hz. In general, the frequencies of many anthropogenic 
sounds, particularly those produced by construction activities, are 
below 1 kHz (Richardson et al., 1995). When sounds at frequencies 
greater than 1 kHz are produced, they generally attenuate relatively 
rapidly (Richardson et al., 1995), particularly above 20 kHz due to 
propagation losses and absorption (Urick, 1983).
    Transmission loss (TL) defines the degree to which underwater sound 
has spread in space and lost energy after having moved through the 
environment and reached a receiver. It is defined by the International 
Standards Organization (ISO) as the reduction in a specified level 
between two specified points that are within an underwater acoustic 
field (ISO, 2017). Careful consideration of transmission loss and 
appropriate propagation modeling is a crucial step in determining the 
impacts of underwater sound, as it helps to define the ranges 
(isopleths) to which impacts are expected and depends significantly on 
local environmental parameters such as seabed type, water depth 
(bathymetry), and the local speed of sound. Geometric spreading laws 
are powerful tools which provide a simple means of estimating TL, based 
on the shape of the sound wave front in the water column. For a sound 
source that is equally loud in all directions and in deep water, the 
sound field takes the form of a sphere, as the sound extends in every 
direction uniformly. In this case, the intensity of the sound is spread 
across the surface of the sphere, and thus we can relate intensity loss 
to the square of the range (as area = 4*pi*r\2\). When expressing 
logarithmically in dB as TL, we find that TL = 
20*Log10(range), this situation is known as spherical 
spreading. In shallow water, the sea surface and seafloor will bound 
the shape of the sound, leading to a more cylindrical shape, as the top 
and bottom of the sphere is truncated by the largely reflective 
boundaries. This situation is termed cylindrical spreading, and is 
given by TL = 10*Log10(range) (Urick, 1983). An intermediate 
scenario may be defined by the equation TL = 
15*Log10(range), and is referred to as practical spreading. 
Though these geometric spreading laws do not capture many often 
important details (scattering, absorption, etc.), they offer a 
reasonable and simple approximation of how sound decreases in intensity 
as it is transmitted. In the absence of measured data indicating the 
level of transmission loss at a given site for a specific activity, 
NMFS recommends practical spreading (i.e., 15*Log10(range)) 
to model acoustic propagation for construction activities in most 
nearshore environments.

[[Page 61538]]

    The sum of the various natural and anthropogenic sound sources at 
any given location and time depends not only on the source levels, but 
also on the propagation of sound through the environment. 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, background and ambient sound levels can be expected to vary 
widely over both coarse and fine spatial and temporal scales. Sound 
levels at a given frequency and location can vary by 10-20 dB from day 
to day (Richardson et al., 1995). The result is that, depending on the 
source type and its intensity, sound from the specified activity may be 
a negligible addition to the local environment or could form a 
distinctive signal that may affect marine mammals.

Description of Sound Sources for the Specified Activities

    In-water construction activities expected to generate sound at 
levels resulting in Level B harassment include impact pile 
installation. 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 impulsive, 
characterized by rapid rise times and high peak levels, a potentially 
injurious combination (Hastings and Popper, 2005).
    The likely or possible impacts of the Columbia Gulf's proposed 
activities on marine mammals could involve both non-acoustic and 
acoustic stressors. Potential non-acoustic stressors could result from 
the physical presence of the equipment and personnel; however, visual 
and other non-acoustic stressors would be limited, and any impacts to 
marine mammals are expected to primarily be acoustic in nature.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving or drilling is the primary means by which 
marine mammals may be harassed from the Columbia Gulf's specified 
activity. In general, animals exposed to natural or anthropogenic sound 
may experience physical and psychological effects, ranging in magnitude 
from none to severe (Southall et al., 2007; 2019). Exposure to pile 
driving has the potential to result in auditory threshold shifts and 
behavioral reactions (e.g., avoidance, temporary cessation of foraging 
and vocalizing, changes in dive behavior). Exposure to anthropogenic 
noise can also lead to non-observable physiological responses, such an 
increase in stress hormones. Additional noise in a marine mammal's 
habitat can mask acoustic cues used by marine mammals to carry out 
daily functions, such as communication and predator and prey detection. 
The effects of pile driving on marine mammals is 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. 
mom with calf), duration of exposure, the distance between the pile and 
the animal, received levels, behavior at time of exposure, and previous 
history with exposure (Wartzok et al., 2004; Southall et al., 2007). 
Here we discuss physical auditory effects (threshold shifts) followed 
by behavioral effects and potential impacts on habitat.
    NMFS defines a noise-induced threshold shift (TS) as a change, 
usually an increase, in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS, 2018, there are numerous factors to 
consider when examining the consequence of TS, including, but not 
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough 
duration or to a high enough level to induce a TS, the magnitude of the 
TS, time to recovery (seconds to minutes or hours to days), the 
frequency range of the exposure (i.e., spectral content), the hearing 
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). When considering auditory effects for Columbia Gulf's 
proposed activities, impact pile driving is treated as an impulsive 
source.
    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). PTS does not 
generally affect more than a limited frequency range, and an animal 
that has incurred PTS has incurred some level of hearing loss at the 
relevant frequencies; typically animals with PTS are not functionally 
deaf (Au and Hastings, 2008; Finneran, 2016). 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, as with the 
exception of a single study unintentionally inducing PTS in a harbor 
seal (Kastak et al., 2008), there are no empirical data measuring PTS 
in marine mammals largely due to the fact that, for various ethical 
reasons, experiments involving anthropogenic noise exposure at levels 
inducing PTS are not typically pursued or authorized (NMFS, 2018).
    Temporary Threshold Shift (TTS)--A temporary, reversible increase 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018). Based on data from marine mammal TTS measurements 
(see Southall et al. (2007; 2019)), 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 (Finneran et 
al., 2000; Schlundt et al., 2000; Finneran et al., 2002). As described 
in Finneran (2015), marine mammal studies have shown the amount of TTS 
increases with 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.,

[[Page 61539]]

2007), so we can infer that strategies exist for coping with this 
condition to some degree, though likely not without cost.
    Many studies have examined noise-induced hearing loss in marine 
mammals (see Finneran (2015) and Southall et al. (2019) for summaries). 
TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. For 
cetaceans, published data on the onset of TTS are limited to captive 
bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise (Phocoena phocoena), and Yangtze finless 
porpoise (Neophocoena asiaeorientalis) (Southall et al., 2019). These 
studies examine hearing thresholds measured in marine mammals before 
and after exposure to intense or long-duration sound exposures. The 
difference between the pre-exposure and post-exposure thresholds can be 
used to determine the amount of threshold shift at various post-
exposure times.
    The amount and onset of TTS depends on the exposure frequency. 
Sounds at low frequencies, well below the region of best sensitivity 
for a species or hearing group, are less hazardous than those at higher 
frequencies, near the region of best sensitivity (Finneran and 
Schlundt, 2013). 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; 2019c). Note that in general, harbor 
seals and harbor porpoises have a lower TTS onset than other measured 
pinniped or cetacean species (Finneran, 2015). 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 
(Mooney et al., 2009; Finneran et al., 2010; Kastelein et al., 2014; 
2015). 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. Nachtigall et al. (2018) describe 
measurements of hearing sensitivity of multiple odontocete species 
(bottlenose dolphin, harbor porpoise, beluga, and false killer whale 
(Pseudorca crassidens)) when a relatively loud sound was preceded by a 
warning sound. These captive animals were shown to reduce hearing 
sensitivity when warned of an impending intense sound. Based on these 
experimental observations of captive animals, the authors suggest that 
wild animals may dampen their hearing during prolonged exposures or if 
conditioned to anticipate intense sounds. Another study showed that 
echolocating animals (including odontocetes) might have anatomical 
specializations that might allow for conditioned hearing reduction and 
filtering of low-frequency ambient noise, including increased stiffness 
and control of middle ear structures and placement of inner ear 
structures (Ketten et al., 2021). Data available on noise-induced 
hearing loss for mysticetes are currently lacking (NMFS, 2018). 
Additionally, the existing marine mammal TTS data come from a limited 
number of individuals within these species.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above that inducing mild TTS (e.g., a 40-dB threshold 
shift approximates PTS onset (Kryter et al., 1966; Miller, 1974), while 
a 6-dB threshold shift approximates TTS onset (Southall et al., 2007; 
2019). Based on data from terrestrial mammals, a precautionary 
assumption is that the PTS thresholds for impulsive sounds (such as 
impact pile driving pulses as received close to the source) are at 
least 6 dB higher than the TTS threshold on a peak-pressure basis and 
PTS cumulative sound exposure level thresholds are 15 to 20 dB higher 
than TTS cumulative sound exposure level thresholds (Southall et al., 
2007; 2019). Given the higher level of sound or longer exposure 
duration necessary to cause PTS as compared with TTS, it is 
considerably less likely that PTS could occur.
    Behavioral Harassment--Exposure to noise also has the potential to 
behaviorally disturb marine mammals to a level that rises to the 
definition of harassment under the MMPA. Generally speaking, NMFS 
considers a behavioral disturbance that rises to the level of 
harassment under the MMPA a non-minor response--in other words, not 
every response qualifies as behavioral disturbance, and for responses 
that do, those of a higher level, or accrued across a longer duration, 
have the potential to affect foraging, reproduction, or survival. 
Behavioral disturbance may include a variety of effects, including 
subtle changes in behavior (e.g., minor or brief avoidance of an area 
or changes in vocalizations), more conspicuous changes in similar 
behavioral activities, and more sustained and/or potentially severe 
reactions, such as displacement from or abandonment of high-quality 
habitat. Behavioral responses may include changing durations of 
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral 
activities (such as socializing or feeding); eliciting a visible 
startle response or aggressive behavior (such as tail/fin slapping or 
jaw clapping); avoidance of areas where sound sources are located. 
Behavioral responses to sound are highly variable and context-specific 
and any reactions depend on numerous intrinsic and extrinsic factors 
(e.g., species, state of maturity, experience, current activity, 
reproductive state, auditory sensitivity, time of day), as well as the 
interplay between factors (e.g., Richardson et al., 1995; Wartzok et 
al., 2004; Southall et al., 2007; Weilgart, 2007; Archer et al., 2010; 
Southall et al., 2019). 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). Please see 
Appendices B and C of Southall et al. (2007) and Gomez et al. (2016) 
for reviews of studies involving marine mammal behavioral responses to 
sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2004). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure.
    As noted above, behavioral state may affect the type of response. 
For example,

[[Page 61540]]

animals that are resting may show greater behavioral change in response 
to disturbing sound levels than animals that are highly motivated to 
remain in an area for feeding (Richardson et al., 1995; Wartzok et al., 
2004; National Research Council (NRC), 2005). Controlled experiments 
with captive marine mammals have showed pronounced behavioral 
reactions, including avoidance of loud sound sources (Ridgway et al., 
1997; Finneran et al., 2003). Observed responses of wild marine mammals 
to loud pulsed sound sources (typically seismic airguns or acoustic 
harassment devices) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Richardson 
et al., 1995; Morton and Symonds, 2002; Nowacek et al., 2007).
    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). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior 
may reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Respiration rates vary naturally with different behaviors and 
alterations to breathing rate as a function of acoustic exposure can be 
expected to co-occur with other behavioral reactions, such as a flight 
response or an alteration in diving. However, respiration rates in and 
of themselves may be representative of annoyance or an acute stress 
response. Various studies have shown that respiration rates may either 
be unaffected or could increase, depending on the species and signal 
characteristics, again highlighting the importance in understanding 
species differences in the tolerance of underwater noise when 
determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001; 2005; 2006; Gailey et 
al., 2007).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Fristrup et al., 2003) or vocalizations (Foote et al., 2004), 
respectively, while North Atlantic right whales (Eubalaena glacialis) 
have been observed to shift the frequency content of their calls upward 
while reducing the rate of calling in areas of increased anthropogenic 
noise (Parks et al., 2007). In some cases, animals may cease sound 
production during production of aversive signals (Bowles et al., 1994).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
(Eschrictius robustus) are known to change direction--deflecting from 
customary migratory paths--in order to avoid noise from seismic surveys 
(Malme et al., 1984). Avoidance may be short-term, with animals 
returning to the area once the noise has ceased (e.g., Bowles et al., 
1994; Goold, 1996; Stone et al., 2000; Morton and Symonds, 2002; Gailey 
et al., 2007). Longer-term displacement is possible, however, which may 
lead to changes in abundance or distribution patterns of the affected 
species in the affected region if habituation to the presence of the 
sound does not occur (e.g., Blackwell et al., 2004; Bejder et al., 
2006; Teilmann et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996; Bowers et al., 2018). The result of a flight response 
could range from brief, temporary exertion and displacement from the 
area where the signal provokes flight to, in extreme cases, marine 
mammal strandings (England et al., 2001). However, it should be noted 
that response to a perceived predator does not necessarily invoke 
flight (Ford and Reeves, 2008), and whether individuals are solitary or 
in groups may influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fishes and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch, 1992; Daan

[[Page 61541]]

et al., 1996; Bradshaw et al., 1998). However, Ridgway et al. (2006) 
reported that increased vigilance in bottlenose dolphins exposed to 
sound over a 5-day period did not cause any sleep deprivation or stress 
effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    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-
pituitary-adrenal 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 glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2005), however 
distress is an unlikely result of this project based on observations of 
marine mammals during previous, similar construction projects and given 
the anticipated effectiveness of proposed mitigation measures.
    Auditory Masking--Since many marine mammals rely on sound to find 
prey, moderate social interactions, and facilitate mating (Tyack, 
2008), noise from anthropogenic sound sources can interfere with these 
functions, but only if the noise spectrum overlaps with the hearing 
sensitivity of the receiving marine mammal (Southall et al., 2007; 
Clark et al., 2009; Hatch et al., 2012). Chronic exposure to excessive, 
though not high-intensity, noise could cause masking at particular 
frequencies for marine mammals that utilize sound for vital biological 
functions (Clark et al., 2009). Acoustic masking is when other noises 
such as from human sources interfere 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; Erbe et al., 2016). Therefore, under certain 
circumstances, marine mammals whose acoustical sensors or environment 
are being severely masked could also be impaired from maximizing their 
performance fitness for survival and reproduction. 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-to-noise 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 (Hotchkin and 
Parks, 2013).
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is human-made, it may be considered 
harassment when disrupting or altering critical behaviors. It is 
important to distinguish TTS and PTS, which persist after the sound 
exposure, from masking, which occurs during the sound exposure. Because 
masking (without resulting in TS) is not associated with abnormal 
physiological function, it is not considered a physiological effect, 
but rather a potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
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). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or

[[Page 61542]]

through other compensatory behaviors (Hotchkin and Parks, 2013). 
Masking can be tested directly in captive species (e.g., Erbe, 2008), 
but in wild populations it must be either modeled or inferred from 
evidence of masking compensation. There are few studies addressing 
real-world masking sounds likely to be experienced by marine mammals in 
the wild (e.g., Branstetter et al., 2013).
    Marine mammals at or near the project site may be exposed to 
anthropogenic noise which may lead to some habituation, but is also a 
source of masking. Vocalization changes may result from a need to 
compete with an increase in background noise and include increasing the 
source level, modifying the frequency, increasing the call repetition 
rate of vocalizations, or ceasing to vocalize in the presence of 
increased noise (Hotchkin and Parks, 2013).
    Masking is more likely to occur in the presence of broadband, 
relatively continuous noise sources. Energy distribution of pile 
driving covers a broad frequency spectrum, and sound from pile driving 
would be within the audible range of marine mammals. While some 
construction during Columbia Gulf's activities may mask some acoustic 
signals that are relevant to the daily behavior of BBES dolphins if 
they are in the vicinity of the project, the short-term duration and 
limited areas affected make it very unlikely that reproductive success 
or survival of individual animals would be affected.
    Water quality--Temporary and localized reduction in water quality 
will occur as a result of in-water construction activities. The 
installation of piles and proposed dredging for pipeline installation 
will disturb bottom sediments and will cause a temporary increase in 
suspended sediment in the project area. In general, turbidity 
associated with pile driving is localized to about a 25-ft (7.6m) 
radius around the pile (Everitt et al. 1980). The small resulting 
sediment plume is expected to settle out of the water column within a 
few hours. Studies of the effects of turbid water on fish (marine 
mammal prey) suggest that concentrations of suspended sediment can 
reach thousands of milligrams per liter before an acute toxic reaction 
is expected (Burton, 1993).
    Effects from project-related turbidity and sedimentation are 
expected to be short-term, minor, and localized. Following the 
completion of sediment-disturbing activities, suspended sediments in 
the water column are expected to dissipate and return to background 
levels. In general, turbidity within the water column can contribute to 
reduced oxygen levels in the water and can irritate the gills of prey 
fish species in the proposed project area. However, turbidity plumes 
associated with the project would be temporary and localized, and fish 
in the proposed project area would be able to move away from and avoid 
the areas where plumes may occur. Therefore, it is expected that the 
impacts on prey fish species from turbidity, and therefore on marine 
mammals, would be minimal and temporary. In general, the area that may 
be impacted by the proposed construction activities is relatively small 
compared to the available marine mammal habitat in Barataria Bay.
    In addition to sediment, due to the natural and human history of 
Barataria bay, work that disturbs the substrate could encounter 
residual, undetected petroleum material deposited as a result of 
naturally occurring seeps or that resulted from past extraction 
activities. The most likely location for encountering such material is 
in at the coastline and within or proximate to the intertidal zone. 
Columbia Gulf will take all appropriate precautions to prevent the 
resuspension of contaminated media and will notify all appropriate 
authorities if weathered oil is encountered during construction 
activities
    Potential Effects on Prey--Sound may affect marine mammals through 
impacts on the abundance, behavior, or distribution of prey species 
(e.g., crustaceans, cephalopods, fishes, zooplankton). Marine mammal 
prey varies by species, season, and location and, for some, is not well 
documented. Studies regarding the effects of noise on known marine 
mammal prey are described here.
    Fishes 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 et al., 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 that are especially strong and/or intermittent 
low-frequency sounds. Short duration, sharp sounds can cause overt or 
subtle changes in fish behavior and local distribution. The reaction of 
fish to noise depends on the physiological condition 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 
fishes (e.g. Scholik and Yan, 2001; 2002; Popper and Hastings, 2009). 
Several studies have demonstrated that impulse sounds might affect the 
distribution and behavior of some fishes, potentially impacting 
foraging opportunities or increasing energetic costs (e.g., Fewtrell 
and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; 
Santulli et al., 1999; Paxton et al., 2017). However, some studies have 
shown no or slight reaction to impulse sounds (e.g., Pe[ntilde]a et 
al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et 
al., 2012. More commonly, though, the impacts of noise on fishes are 
temporary.
    SPLs of sufficient strength have been known to cause injury to 
fishes and fish mortality (summarized in Popper et al. (2014)). 
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. (2012b) 
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., 2012a; Casper et al., 2013; Casper et al., 2017).
    Fish populations in the proposed project area that serve as marine 
mammal prey could be temporarily affected by noise from pile 
installation. The frequency range in which fishes generally perceive 
underwater sounds is 50 to 2,000 Hz, with peak sensitivities below 800 
Hz (Popper and Hastings, 2009). Fish behavior or distribution may 
change, especially with strong and/or intermittent sounds that could 
harm fishes. High underwater SPLs have been documented to alter 
behavior, cause hearing loss, and injure or kill individual fish by 
causing serious

[[Page 61543]]

internal injury (Hastings and Popper, 2005).
    The greatest potential impact to fishes during construction would 
occur during impact pile driving. In-water construction activities 
would only occur during daylight hours, allowing fish to forage and 
transit the project area in the evening. In general, impacts on marine 
mammal prey species are expected to be minor and temporary.
    Potential Effects on Foraging Habitat--The proposed activities 
would not result in permanent impacts to habitats used directly by 
marine mammals. The total seafloor area affected by the project during 
construction is estimated to be 2.79 acres, of which .02 acres would be 
permanently altered. This alteration represents a small portion of the 
foraging area available to marine mammals outside this project vicinity 
and in broader Barataria Bay. Construction would have minimal impacts 
on invertebrate species (principally shrimp), which have been 
identified as target prey of BBES dolphins (Bowens-Stevens, 2021). 
Barataria Bay is designated as essential fish habitat for several 
species, some of which serve as prey for BBES dolphins. However, given 
the short daily duration of sound associated with individual pile 
driving and the relatively small areas being affected, pile driving 
associated with the project is not likely to have a permanent adverse 
effect on any fish habitat, or populations of fish species. Also, the 
area impacted by the project is relatively small compared to the 
available habitat just outside the project area. Therefore, impacts of 
the project are not likely to have adverse effects on marine mammal 
foraging habitat in the proposed project area.
    In summary for this project, serious injuries to or mortality of 
BBES dolphins are not anticipated as a result of shore side activities 
or in-water construction for the project and neither, as described in 
greater detail in the Estimated Take section, is PTS (Level A 
harassment). However, behavioral impacts could occur due to the 
increase in underwater noise resulting from pile driving activities. 
Potential acoustic disturbance originating from the specified 
activities considered here is expected to be of a relatively short 
duration, likely in the form of avoidance of the area while activities 
are being conducted. Pile driving is proposed to take place from 7 a.m. 
to 7 p.m. (adjusted as appropriate to conduct work during daylight 
hours), and may occur on any day of the week for approximately 25 days 
of in-water work. Bottlenose dolphins are expected to avoid the project 
area during pile driving activities, though dolphins could be present 
when pile driving begins. Columbia Gulf proposes to implement 
mitigation measures such as pre-clearance monitoring and adherence to a 
soft-start protocol in order to mitigate against adverse impacts to 
dolphins that may be in the area when work commences or is restarted. 
Sufficient monitoring will be maintained in order to detect marine 
mammals in the area and implement any necessary response including work 
stoppage, should it become necessary.
    The specified activity could cause localized impacts to dolphin 
prey, but is otherwise unlikely to affect habitat. While some injury or 
loss of prey animals may occur, fish are expected to avoid the project 
area during pile driving activities and changes in abundance of prey 
are not expected.

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers,'' and the negligible impact 
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 for individual marine mammals 
resulting from exposure to sound emanated from pile driving activity. 
Based on the nature of the activity and the anticipated effectiveness 
of the mitigation measures including the utilization of Protected 
Species Observers to monitor for marine mammals and implementation of 
pre-clearance and soft start protocols discussed in detail below in the 
Proposed Mitigation 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 for 
example, permanent threshold shift (or PTS); (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-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile 
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-

[[Page 61544]]

explosive 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 Temporary Threshold Shift (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 that would not otherwise occur.
    Columbia Gulf's Request for Authorization includes actions known to 
generate impulsive sound (impact pile driving) that may cause 
incidental harassment, and therefore the RMS SPL threshold of 160 re 1 
[mu]Pa is 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 non-impulsive). The 
specified activity proposed by Columbia Gulf includes the use of an 
impulsive source type and is proposed to occur in an area where BBES 
bottlenose dolphins, a mid-frequency cetacean, are found.
    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, available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     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     Cell 2 LE,LF,24h: 199 dB
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3 Lpk,flat: 230 dB     Cell 4 LE,MF,24h: 198 dB
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5 Lpk,flat: 202 dB     Cell 6 LE,HF,24h: 173 dB
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7 Lpk,flat: 218 dB     Cell 8 LE,PW,24h: 201 dB
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9 Lpk,flat: 232 dB     Cell 10 LE,OW,24h: 219 dB
                                          LE,OW,24h: 203 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 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[mu]Pa\2\s. 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.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area that may be ensonified to 
levels above the acoustic thresholds, including source levels and 
transmission loss coefficient.
    To calculate the ensonified area, Columbia Gulf used the NMFS User 
Spreadsheet and accompanying 2018 guidance. Columbia Gulf located data 
for impact installation of a 36 inch concrete pile (McGillvary, 2007), 
measured at 50 meters, to serve as a suitable proxy source level for 
the 104 36-inch spun-cast piles selected for the project (see Table 6). 
The applicant then elected to apply the source levels for the 36-in 
proxy pile to all piles being driven, including the 20 18-inch piles, 
likely resulting in an overestimate of resulting noise from these 
smaller piles.
    Transmission loss (TL) is the decrease in acoustic intensity as an 
acoustic pressure wave propagates out from a source. TL parameters vary 
with frequency, temperature, sea conditions, current, source and 
receiver depth, water depth, water chemistry and bottom composition and 
topography. The general formula for underwater TL is:

TL = B * Log10 (R1/R2), where:
TL = Transmission loss in dB,
B = Transmission loss coefficient,
R1 = the distance of the modeled SPL from the driving pile, and
R2 = the distance from the driven pile of the initial measurement.

    Absent site-specific acoustical monitoring with differing measured 
transmission loss, a practical spreading value of 15 is used as the 
transmission loss coefficient. Site-specific transmission loss data for 
the project area in Barataria Bay is not available; therefore, the 
default coefficient of 15 is used to determine the distances to the 
Level A harassment and Level B harassment thresholds. The ensonified 
area associated with Level A harassment is more technically challenging 
to predict due to the need to account for a duration component. There, 
NMFS developed an optional User Spreadsheet and accompanying 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 the 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 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 options 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. Inputs used in the option User Spresheet tool, and the 
resulting estimated isopleths, are reported in Tables 6 and 7, below. 
The applicant as applied a 15LogR propagation loss rate in the User 
Spreadsheet, and included a 5 dB attenuation factor for proposed use of 
a bubble curtain which is consistent with NMFS guidelines.

[[Page 61545]]



                          Table 6--Proxy Pile Characteristics (User Spreadsheet Input)
----------------------------------------------------------------------------------------------------------------
                                                    SLs
           Pile type            ------------------------------------------  Measured distance        Source
                                    dB Peak       dB rms        dB SEL
----------------------------------------------------------------------------------------------------------------
36'' concrete pile, Impact pile          186           174           160   50 meters.........  MacGillivary,
 driven (5 dB attenuated).                                                                      2007.
----------------------------------------------------------------------------------------------------------------

    To calculate the harassment zones, Columbia Gulf identified a 
representative location in the center of the Tie-in Facility and second 
representative location in the center of the POD Meter Station and used 
these locations to calculate the harassment zones for each site. Given 
the close proximity of individual piles to one another, NMFS concurred 
with this approach. Columbia Gulf then accessed the User Spreadsheet to 
calculate the distance from each of the two representative pile driving 
locations to the furthest extent of Level A and Level B thresholds for 
mid-frequency cetaceans. In order to ensure conservative results, the 
source level data for 36 inch piles was used as a proxy for all pile 
driving activities, including installation of smaller diameter piles.

Table 7--Harassment Zone Isopleths Attributable To Proposed Pile Driving
------------------------------------------------------------------------
                                    Distance from representative sound
                                                  source
                                 ---------------------------------------
                                                          Behavioral
            Activity                 PTS: Level A     disturbance: Level
                                    harassment zone    B harassment zone
                                    (mid-frequency        (all marine
                                      cetaceans)           mammals)
------------------------------------------------------------------------
Impact pile driving in Barataria  142.0 feet........  1,407.0 feet.
 Bay \a\.
------------------------------------------------------------------------
\a\ User Spreadsheet output based on installation by impact hammer of
  (proxy) 36-inch-diameter concrete piles, and use of bubble curtains
  (estimated 5 dB reduction, per consultations with NMFS) (MacGillivray
  et al., 2007).

    Based on the user spreadsheet outputs reflected in Table 5, the 
Level B harassment zone would have a radius of approximately 1,407.0 
feet (428.9 meters) from the source pile, or an approximate area of 
0.58 square kilometers (km\2\). The Level A zone would have a 
calculated radius of approximately 142.0 feet (43.2 meters), or an 
approximate area of 63,347 square feet (0.006 km\2\). Columbia Gulf 
plans to implement a 50 meter shutdown zone that extends coverage 
beyond the 43.2 meter Level A harassment zone indicated by the User 
Spreadsheet. As a result, given that detection of bottlenose dolphins 
within this distance is expected to be successful, no Level A take is 
anticipated to occur, or proposed to be authorized, as a result of 
project activities.

Marine Mammal Occurrence

    In order to estimate the distribution and density of BBES dolphins 
that may occur in the area affected by the specified activity, we turn 
to prior area-specific surveys and studies conducted in the Bay.
    Density estimates for Columbia Gulf's proposal reference the 
findings of the 2017 McDonald (et al.) study and an average of the 
calculated densities for each habitat region defined within the study 
area. Density estimates for bottlenose dolphins within Barataria Bay 
were derived from estimates calculated through vessel-based capture-
mark-recapture photo-ID surveys conducted during ten survey sessions 
from June 2010 to May 2014 (McDonald et.al., 2017). Because the surveys 
were conducted during the DWH oil spill, the resulting density estimate 
does not account for mortality following the spill.
    The study was conducted from June 2010 to May 2014 and utilized 
vessel-based capture-mark-recapture photo ID surveys. The study area 
for these surveys included Barataria Bay and Pass, Bayou Rigaud, 
Caminada Bay and Pass, Barataria Waterway, and Bay des Ilettes. 
Densities varied in different areas within broader Barataria Bay, and 
the study area was divided into three (East, West, and Island) habitat 
regions to capture these observed density variations. Results were 
parsed and densities were calculated for each habitat region. Project 
activities may have some effect on both the East and West habitat 
regions, with estimated densities of 0.601 individuals per km\2\ and 
1.24 individuals per km\2\, respectively. Study results indicate 
density of 11.4 individuals per km\2\ for the Island region. Given 
uncertainties regarding fidelity to and transiting among habitat 
regions, the average densities for each habitat region in the study 
area are then averaged together to create an estimated density for the 
project area. NMFS concurs with this approach. Inclusion of the higher 
estimated density from the Island habitat region results in a 
cumulative average higher than the estimated density for the East and 
West habitat regions alone, and reflects a conservative approach. Based 
on this calculation and using the best available information for 
estimating density given the project type and location, the average 
bottlenose dolphin density for the project is estimated to be 2.83 
individuals per km\2\.

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.

[[Page 61546]]



                                Table 8--Level B Harassment Takes Requested and Percentage of Stock Potentially Affected
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                          Percentage (%)
                                                                                           Level B      Level B takes                        of stock
        Pile driving location                 Species             Estimated density      harassment       requested     Stock abundance    potentially
                                                                                            area        (individuals)    (individuals)     affected by
                                                                                                                                           Level B take
--------------------------------------------------------------------------------------------------------------------------------------------------------
Tie-In Facility.....................  Bottlenose Dolphin       2.83                        0.58 km\2\              40            2,071             1.93
                                                               individuals per km\2\.
POD Meter Station...................  2......................  0.10..................
    Project Totals..................  42.....................  --....................            2.03
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Level B Take estimates for pile driving activities were calculated 
using the density estimate described above, averaging across the three 
areas in Barataria Bay. The Level B harassment zone is calculated using 
source level data for 36-inch concrete piles (including use of bubble 
curtains) and assumes an even distribution of animals throughout the 
affected area. Initial Level B take estimates for Tie-in Facility and 
POD Meter Station pile driving activity were calculated using the area 
of the Level B harassment zone (0.58 km\2\) multiplied by the 
calculated density (2.83 individuals per km\2\). This results in a 
daily take estimate of 1.64 individuals for pile driving at the Tie-in 
Facility and the POD Meter Station. The daily Level B harassment 
estimate (1.64 individuals) was then multiplied by the number of days 
when pile driving will take place (24 days at the Tie-in Facility and 1 
day at the POD Meter Station) to calculate the number of requested 
takes for pile driving related to the Project. The estimated takes are 
indicated in Table 8.
    Level A harassment is not anticipated to occur and authorization of 
Level A take is not requested. In-water construction activities will be 
completed within one to two months (a total of 25 to 42 days) and are 
not expected to result in serious injury or mortality to marine mammals 
within Barataria Bay. Based on calculated threshold distances in Table 
7 for mid-frequency cetaceans, an individual would need to remain 
within 142.0 feet of the piles being driven throughout the entire day 
of pile driving activities for cumulative exposure injury to occur. 
Given the mobility of bottlenose dolphins and the expected behavior of 
the species to avoid noise disturbance (i.e., pile driving), such a 
scenario is extremely unlikely to occur.

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 implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned), and;
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations.

Mitigation for Marine Mammals and Their Habitat

    Columbia Gulf will retain and deploy qualified Protected Species 
Observers to ensure that dolphins are not present within 1,407.0 feet 
(428.8 meters) of the pile driving area when pile driving activities 
begin. If dolphins are observed entering the area in which the injury 
threshold will be exceeded (i.e., Level A, calculated to be 142.0 feet 
[43.2 meters] and established at 50 meters), pile driving will cease 
until they leave the area. All vessels engaged in construction and crew 
transport will adhere to NMFS's Vessel Strike Avoidance Measures and to 
related reporting requirements for mariners. Through the implementation 
of these measures and those that follow, Columbia Gulf will ensure that 
dolphins and other marine mammals are not present within an area where 
Level A harassment could occur.
    Columbia Gulf proposes the following additional mitigation 
measures:
     Establishment and monitoring of Pre-clearance zones to 
survey for presence of marine mammals prior to commencement/resumption 
of work.
     Implementation of soft start protocols to ensure initial 
sound stimulus is not at a harmful level.
     Adoption of a conservative 50 meter shutdown zone to 
preclude Level A take.
     Positioning of Protected Species Observers authorized to 
direct work stoppage if circumstances warrant.
     Deployment of a submerged bubble curtain to dampen sound 
from impact driving.
     Work stoppage should any marine mammal take not permitted 
by the IHA occur followed by reporting to NOAA Fisheries as soon as 
practicable and within 24 hours.
    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 to BBES 
bottlenose dolphins and their habitat.

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.

[[Page 61547]]

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.
    Below is a summary of the monitoring measures included in the 
application and proposed for pile installation activities associated 
with the Project (see the draft IHA for additional detail):
     At least one NOAA Fisheries-approved observers (i.e., 
Protected Species Observers [PSOs]) will be on duty and assigned to the 
highest possible vantage point in order to maintain a 360-degree view 
of the project area.
     A 1,407.0 feet (428.8 meters) pre-clearance zone for 
marine mammals will be established using range finding equipment and 
monitored by the PSOs.
     Observers will monitor the NOAA-approved 50 meter shutdown 
zone during all pile installation activities.
     Observers will maintain a continuous watch while pile 
driving activities are under way, using binoculars and/or naked eye 
observations to continuously search for marine mammals.
     If marine mammals are observed in the Project area, the 
sighting will be fully documented, including the following (among 
others), when possible:
    [cir] Bearing to animal relative to observer position;
    [cir] Number of individuals observed;
    [cir] Estimated location within the Project area;
    [cir] Type of construction activity (i.e., impact pile driving); 
and
     Behavioral state, possible reaction of the animal(s) to 
the pile driving, and any behaviors of the animal/s while in the 
Project area.Observers will make note of the state of Barataria Bay 
using the Beaufort scale and collect and record weather conditions 
during the course of marine mammal monitoring.

Proposed Reporting

    Columbia Gulf would provide the NOAA Fisheries Service with a draft 
comprehensive monitoring report within 90 days of the conclusion of 
monitoring. This report would include the following (please see draft 
IHA for additional detail):
     A summary of the Project activity (e.g., Project actions, 
dates, times, durations, and locations)
     A summary of mitigation implementation
     Monitoring results and a summary that addresses the goals 
of the monitoring plan, including (but not limited to):
    [cir] Environmental conditions when observations were made (e.g., 
water conditions and weather);
    [cir] Date and time of observations (initiation and termination);
    [cir] Date, time, number, species, and any other relevant data 
regarding marine mammals observed;
    [cir] Description of the observed behaviors; and
    [cir] Assessment of implementation and effectiveness of prescribed 
mitigation and monitoring measures.

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., population-
level 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 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).
    The BBES stock of bottlenose dolphins is considered a strategic 
stock because mortality attributable to human activity is thought to 
exceed PBR. Potential effects of this project on BBES dolphins include 
behavioral modification resulting from Level B harassment and temporary 
avoidance of the construction area. As decribed above, no Level A 
harassment is expected and no authorization of Level A take is not 
proposed. Given the nature of the harassment, its temporary nature and 
proposed mitigation, NMFS anticipates impacts from the specified 
activity on individuals and the stock would be negligible.
    The project site is within a designated Biologically Important Area 
for Small and Resident Populations. The BBES stock is present within 
the area year-round. All life activities may occur within the 
designated BIA including the project area. The project area represents 
a small portion of available habitat and the BIA, and adjacent areas of 
open water within the embayment that would remain accessible to BBES 
dolphins throughout the construction process. Proper implementation of 
the mitigation measures described above support a finding that the 
impacts of Level B harassment would be minimized and likely have 
negligible effect on individual animals or the BBES population of 
bottlenose dolphins.
    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 BBES bottlenose 
dolphins by reducing annual rates of recruitment or survival:

[[Page 61548]]

     No serious injury or mortality is anticipated or 
authorized; and no impacts to reproductive success or survival of any 
individual animals are expected.
     The required mitigation measures are expected to avoid any 
Level A harassment and to reduce the number and severity of takes by 
Level B harassment.
     Behavioral impacts and displacement that may occur in 
response to pile driving, is expected to be limited in duration to 
approximately 25 days concurrent with in-water construction activity.
     The specified activities do not impact any known important 
habitat areas such as calving grounds or unique feeding areas, and 
alternate habitat is readily available.
    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 pile driving activity will have a 
negligible impact on BBES bottlenose dolphins.

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.
    Based on a conservative estimate of the number of takes that may 
occur as a result of pile driving activities, less than two percent of 
the BBES population would be subject to take via Level B harassment.
    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.

Unmitigable Adverse Impact Analysis and Determination

    No subsistence uses of BBES bottlenose dolphins are known to occur. 
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 under the 
auspices of this authorization. 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 Columbia Gulf, LLC to conduct the specified pile 
driving activity in Barataria Bay, Louisiana during the 1-year period 
of authorization, provided the previously mentioned mitigation, 
monitoring, and reporting requirements are incorporated. A draft of the 
proposed IHA can be found at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the specified 
activity. 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 one year from 
expiration of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (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: September 1, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-19310 Filed 9-6-23; 8:45 am]
BILLING CODE 3510-22-P