Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the King Pile Markers Project on the Columbia River, 44866-44884 [2019-18351]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 84, Number 166 (Tuesday, August 27, 2019)]
[Notices]
[Pages 44866-44884]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-18351]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG908


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the King Pile Markers Project on 
the Columbia River

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 U.S. Army Corps of Engineers, 
Portland District (Corps) for authorization to take marine mammals 
incidental to the King Pile Markers Project on the Columbia River in 
Washington and Oregon Pursuant to the Marine Mammal Protection Act 
(MMPA). NMFS is requesting comments on its proposal to issue an 
incidental harassment authorization (IHA) to incidentally take marine 
mammals during the specified activities. NMFS is also requesting 
comments on a possible one-year renewal that could be issued under 
certain circumstances and if all requirements are met, as described in 
Request for Public Comments at the end of this notice. NMFS will 
consider public comments prior to making any final decision on the 
issuance of the requested MMPA authorizations and agency responses will 
be summarized in the final notice of our decision.

DATES: Comments and information must be received no later than 
September 26, 2019.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Physical comments should be sent to 
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments 
should be sent to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or

[[Page 44867]]

received after the end of the comment period. Comments received 
electronically, including all attachments, must not exceed a 25-
megabyte file size. Attachments to electronic comments will be accepted 
in Microsoft Word or Excel or Adobe PDF file formats only. All comments 
received are a part of the public record and will generally be posted 
online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All 
personal identifying information (e.g., name, address) voluntarily 
submitted by the commenter may be publicly accessible. Do not submit 
confidential business information or otherwise sensitive or protected 
information.

FOR FURTHER INFORMATION CONTACT: Robert Pauline, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these 
documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such 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 such 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 (incidental harassment authorizations 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 February 11, 2019, NMFS received a request from the Corps for an 
IHA to take marine mammals incidental to pile driving associated with 
the replacement of king pile markers at numerous dike locations in the 
lower Columbia River system. The king pile markers are located in 
Oregon and Washington between river miles (RM) 41 and 137. The 
application was deemed adequate and complete on August 2, 2019. The 
Corps' request is for take of small numbers of harbor seal (Phoca 
viutlina), Steller sea lion (Eumetopias jubatus), and California sea 
lion (Zalophus californianus) that may occur in the vicinity of the 
project by Level B harassment. Neither the Corps nor NMFS expects 
serious injury or mortality to result from this activity and, 
therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    The Corps is proposing to replace up to 68 king pile markers at 68 
pile dike sites along the lower Columbia River between river miles (RM) 
41 and 137 (see Figure 1). There are a total of 256 pile dikes, in the 
existing dike system. The king piles that require replacement are not 
functioning as intended. They were designed to aid navigation by 
helping mariners avoid pile dikes during high water. Many exiting king 
piles are either missing completely, damaged, or degraded to a point 
where they no longer provide a visual identifier. This lack of 
visibility poses a safety concern to both recreational and commercial 
boaters on the river. Replacement of the king piles will improve 
visibility of pile dikes and improve safety for Columbia River traffic. 
Impact and vibratory pile installation would introduce underwater 
sounds at levels that may result in take, by Level B harassment, of 
marine mammals in the lower Columbia River. Construction activities are 
expected to last 61 days.

Dates and Duration

    Pile installation would be done during the 2019 in-water work 
window of October 1, 2019 to November 30, 2019. Impact driving will 
only take place in November, as per NMFS 2012 SLOPES IV programmatic 
biological opinion. Since the in-water work window is approximately 61 
days and pile installation activity could potentially occur on each day 
of that window, it is estimated that the project could require up to 61 
days. Pile installation will be conducted during standard daylight 
working hours. Up to one hour of impact driving and 30 minutes of 
vibratory driving could occur at each pile dike location per day.

Specific Geographic Region

    Pile dikes are located in both Oregon and Washington on the 
Columbia River between RM 41 and 137. The project area is dominated by 
freshwater inputs from the Columbia and Willamette rivers. The Mouth of 
the Columbia River designated at RM 0 while the Bonneville Dam is 
located at RM 146. The existing depth (relative to Columbia River low 
water datum) at the locations of missing king pile markers varies from 
less than 10 ft. to greater than 30 ft., but is generally in the 20-30 
foot range, possibly indicating scour protection rock thicknesses of up 
to 10 feet.
BILLING CODE 3510-22-P

[[Page 44868]]

[GRAPHIC] [TIFF OMITTED] TN27AU19.000

BILLING CODE 3510-22-C

Detailed Description of Specific Activity

    King pile markers consist of one or more tall piles (up to about 20 
feet above the Columbia River mean low water (MLW) datum) marking the 
end of a pile dike for navigational safety. King piles were originally 
constructed as part of a cluster of piles called an outer dolphin. 
Columbia River pile dikes are permeable groins extending into the river 
and consist of two or three rows of vertical untreated timber pilings 
driven in staggered rows of 5-foot centers alternately placed on each 
side of horizontal spreader piles and fastened together. Rock placed at 
the base of the piles and at the shore connection help protect against 
scour.
    Construction will consist of driving new replacement piles, and 
adding scour protection rock around new piles as needed. Each 
replacement king pile marker will consist of a single steel pipe pile 
of up to 24-inch diameter. Piles will be driven up to 30-35 feet of 
embedment. If piles cannot be driven through the existing scour 
protection rock, the marker will be offset. Scour protection rock (less 
than 25 cubic yards) may be placed around the base of any offset piles. 
The total estimated

[[Page 44869]]

quantity of piles needed for this project is 68 piles.
    Barges will transport all materials (new piles, and scour 
protection rock) to and from the site and serve as staging platforms 
during construction. Barges will be moved by tugboats, then spudded or 
anchored into position.
    At each king pile marker, piles will be installed using vibratory 
drivers (e.g., APE Model 200 vibratory driver or equivalent) and/or 
impact hammers (D-46-42 diesel impact hammer or equivalent) operated 
from a barge-mounted crane. Vibratory driving is the preferred method; 
however, impact driving may be necessary if piles cannot be driven to 
the necessary embedment depth using the vibratory method. Under the 
Standard Local Operating Procedures for Endangered Species (SLOPES) IV 
biological opinion (NMFS 2012a), impact driving in the Columbia River 
is only allowed during the month of November, and must use an acoustic 
attenuation device (e.g., a bubble curtain). This programmatic 
biological opinion examined the effects of implementing standard local 
operating procedures for Corps activities involving inwater or over-
water structures (including pile driving, access management, and minor 
discharges) in Oregon and the south shore of the Columbia River and its 
tributaries. The measures described above are required to protect 17 
fish species, including multiple salmon species (Oncorhynchus sp) as 
well as Southern green sturgeon (Acipenser medirostris) and eulachon 
(Thaleichthys pacificus). Note that the programmatic biological opinion 
does not apply to this proposed IHA, but rather to the Corps' pile 
driving activities. Piles are generally installed by a rig that 
supports the pile leads, raises the pile, and operates a driver. 
Driving shoes may be used.
    It is estimated that each pile will take up to one hour to install 
using vibratory methods with 30 minutes of that time being actual 
driving of the pile. Whether impact or vibratory methods are employed, 
one pile will be installed per pile dike location per day. Depending on 
weather and other logistical constraints, piles will be installed at up 
to 9 locations per day. For piles driven with an impact hammer, there 
are an estimated 550 strikes per pile requiring up to one hour, 
assuming a hammer energy rating of 55,000 ft-lbs and piles being driven 
through a combination of sand and rock (Bainbridge Island Ferry 
Terminal, WSDOT 2018a, 2018b). Actual pile driving rates will vary, and 
a typical day will likely involve fewer locations and fewer strikes.
    The contractor may use multiple pile-driving and material barges to 
facilitate completion of work within the in-water work window. However, 
concurrent work at two or more locations are unlikely to be in close 
proximity to each other.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS's 
website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all marine mammal species with expected potential for 
occurrence in the lower Columbia River and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and ESA and potential biological removal (PBR), where known. 
For taxonomy, we follow Committee on Taxonomy (2016). PBR is defined by 
the MMPA as the maximum number of animals, not including natural 
mortalities, that may be removed from a marine mammal stock while 
allowing that stock to reach or maintain its optimum sustainable 
population (as described in NMFS's SARs). While no mortality is 
anticipated or authorized here, PBR and annual serious injury and 
mortality from anthropogenic sources are included here as gross 
indicators of the status of the species and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS's stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprise that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's 2018 U.S. Pacific Marine Mammal SARs (Carretta et al., 2019). 
All values presented in Table 1 are the most recent available at the 
time of publication and are available in the 2018 SARs (Carretta et 
al., 2019).

                             Table 1--Marine Mammal Species Likely To Be in Lower Columbia River Near King Pile Marker Sites
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                                                                                         ESA/ MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
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                                                         Order Carnivora--Superfamily Pinnipedia
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Family Otariidae (eared seals and
 sea lions):
    California sea lion.............  Zalophus californianus.  U.S. Stock.............  -, -, N             257,606 (N/A, 233,515,     14,011       >320
                                                                                                             2014).
    Steller sea lion................  Eumetopias jubatus.....  Eastern U.S............  -, -, N             41,638 (See SAR,            2,498        108
                                                                                                             41,638, 2015).
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina           Oregon and Washington    -, -, N             UNK (UNK, UNK, 1999)..        UND       10.6
                                       richardii.               Coast.
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\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance. In some cases, CV is not applicable.

[[Page 44870]]

 
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.

    All species that could potentially occur in the proposed survey 
areas are included in Table 1. All three species (with three managed 
stocks) described below co-occur temporally and spatially co-occur with 
the proposed activity to the degree that take is reasonably likely to 
occur, and we have proposed authorizing it.

California Sea Lion

    California sea lions are found along the west coast from the 
southern tip of Baja California to southeast Alaska. They breed mainly 
on offshore islands from Southern California's Channel Islands south to 
Mexico. Non-breeding males often roam north in spring foraging for 
food. Since the mid-1980s, increasing numbers of California sea lions 
have been documented feeding on fish along the Washington coast and--
more recently--in the Columbia River as far upstream as Bonneville Dam, 
145 mi (233 km) from the river mouth. Large numbers of California sea 
lions also use the South Jetty at the Mouth of Columbia River for 
hauling out (Jeffries 2000). The jetty is located approximately 40 
miles downriver from the nearest king pile that would be replaced.
    Oregon Department of Fish and Wildlife survey information (2007 and 
2014) indicates that California sea lions are relatively less prevalent 
in the Pacific Northwest during June and July, though in the months 
just before and after their absence there can be several hundred using 
the South Jetty. More frequent Washington Department of Fish and 
Wildlife surveys (2014) indicate greater numbers in the summer, and use 
remains concentrated to fall and winter months. Nearly all California 
sea lions in the Pacific Northwest are sub-adult and adult males 
(females and young generally stay in California).
    Although coast wide the population has grown, the numbers seen in 
the river and upstream at Bonneville dam during both the spring and 
fall/winter observation periods have decreased since 2003. This may be 
in due to the California sea lion management activities that have been 
implemented to reduce their predation rates on salmon and steelhead. 
These activities include hazing of all California sea lions near the 
dam and fish ladders, as well as the lethal removal of the individuals 
with the highest predation rates (Tidwell et al. 2019).

Steller Sea Lion

    The range of the Steller sea lion includes the North Pacific Ocean 
rim from California to northern Japan. Steller sea lions forage in 
nearshore and pelagic waters where they are opportunistic predators. 
Steller sea lion populations that primarily occur east of 144[deg] W 
(Cape Suckling, Alaska) comprise the Eastern Distinct Population 
Segment (DPS) (Carretta et al. 2019). Stellar sea lions (Eumetopias 
jubatus) are currently the most common marine mammal observed in the 
proposed action area. They are frequently observed between the river's 
mouth (RM 0) and the Bonneville Dam tailrace (RM 146). Large numbers of 
Steller sea lions use the South Jetty for hauling out (Jeffries 2000) 
and are present, in varying abundances, all year.
    During an August-December monitoring period the number of 
individuals observed at Bonneville Dam has been increasing for the past 
decade (Tidwell et al. 2019). The Bonneville dam observation area is 
approximately 10 miles upstream of the nearest king pile that is 
proposed for replacement under this IHA.

Harbor Seal

    Harbor seals range from Baja California, north along the western 
coasts of the United States, British Columbia and southeast Alaska, 
west through the Gulf of Alaska, Prince William Sound, and the Aleutian 
Islands, and north in the Bering Sea to Cape Newenham and the Pribilof 
Islands. They are one of the most abundant pinnipeds in Oregon and can 
typically be found in coastal marine and estuarine waters of the Oregon 
coast throughout the year. On land, they can be found on offshore rocks 
and islands, along shore, and on exposed flats in the estuary (Harvey 
1987). They haul out on rocks, reefs, beaches, and drifting glacial ice 
and feed in marine, estuarine, and occasionally fresh waters. Harbor 
seals generally are non-migratory, with local movements associated with 
tides, weather, season, food availability, and reproduction. Harbor 
seals do not make extensive pelagic migrations (Carretta et al. 2019). 
Major haul-out sites with more than 500 individuals have been noted in 
the Columbia River and are downstream of Tongue Point, about 25 miles 
downstream of the nearest king pile driving location proposed for this 
project (Jeffries 2000). They are uncommon upstream near the Bonneville 
dam in all seasons.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for 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 2.

                                      Table 2--Marine Mammal Hearing Groups
                                                  [NMFS, 2018]
----------------------------------------------------------------------------------------------------------------
                     Hearing group                                     Generalized hearing range *
----------------------------------------------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen whales)...........  7 Hz to 35 kHz.

[[Page 44871]]

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

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Three pinniped species (two otariid and one phocid) have the reasonable 
potential to co-occur with the proposed survey activities. Please refer 
to Table 2

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals and 
their habitat. The Estimated Take by Incidental Harassment section 
later in this document includes a quantitative analysis of the number 
of individuals that are expected to be taken by this activity. The 
Negligible Impact Analysis and Determination section considers the 
content of this section, the Estimated Take by Incidental Harassment 
section, and the Proposed Mitigation section, to draw conclusions 
regarding the likely impacts of these activities on the reproductive 
success or survivorship of individuals and how those impacts on 
individuals are likely to impact marine mammal species or stocks.
    Acoustic effects on marine mammals during the specified activity 
can occur from vibratory and impact pile driving. The effects of 
underwater noise from the Corps' proposed activities have the potential 
to result in Level A and Level B harassment of marine mammals in the 
vicinity of the project area.

Description of Sound Sources

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is 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, e.g., Au and Hastings (2008); Richardson et al. (1995); 
Urick (1983).
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks 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, except in certain cases in shallower water. Amplitude is the 
height of the sound pressure wave or the ``loudness'' of a sound and is 
typically described using the relative unit of the dB. A sound pressure 
level (SPL) in dB is described as the ratio between a measured pressure 
and a reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)), 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. The source level (SL) represents the 
SPL referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa), while the received level is the SPL at the listener's position 
(referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they may be accounted for in the summation of 
pressure levels (Hastings and Popper, 2005). This measurement is often 
used in the context of discussing behavioral effects, in part because 
behavioral effects, which often result from auditory cues, may be 
better expressed through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB 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 is calculated over the time window 
containing the entire pulse (i.e., 100 percent of the acoustic energy). 
SEL is a cumulative metric; it can be accumulated over a single pulse, 
or calculated over periods containing multiple pulses. Cumulative SEL 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. Peak sound pressure (also referred to 
as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source, and is represented in the same units as the rms sound pressure.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or 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 aquatic life and man-made sound receptors such as 
hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound, which is 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al., 1995). The sound

[[Page 44872]]

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 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, 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 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 ambient 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 ambient sound for frequencies between 20 and 300 
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz 
and, if higher frequency sound levels are created, they attenuate 
rapidly.
    The sum of the various natural and anthropogenic sound sources that 
comprise ambient sound at any given location and time depends not only 
on the source levels (as determined by current weather conditions and 
levels of biological and human activity) but also on the ability of 
sound to propagate through the environment. In turn, sound propagation 
is dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 dB from day to day (Richardson et al., 1995). The result 
is that, depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al. (2007) for an in-depth discussion of these concepts. 
The distinction between these two sound types is not always obvious, as 
certain signals share properties of both pulsed and non-pulsed sounds. 
A signal near a source could be categorized as a pulse, but due to 
propagation effects as it moves farther from the source, the signal 
duration becomes longer (e.g., Greene and Richardson, 1988).
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or intermittent (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    The impulsive sound generated by impact hammers is characterized by 
rapid rise times and high peak levels. Vibratory hammers produce non-
impulsive, continuous noise at levels significantly lower than those 
produced by impact hammers. Rise time is slower, reducing the 
probability and severity of injury, and sound energy is distributed 
over a greater amount of time (e.g., Nedwell and Edwards, 2002; Carlson 
et al., 2005).

Acoustic Effects on Marine Mammals

    We previously provided general background information on marine 
mammal hearing (see ``Description of Marine Mammals in the Area of the 
Specified Activity''). Here, we discuss the potential effects of sound 
on marine mammals.
    Note that, in the following discussion, we refer in many cases to a 
review article concerning studies of noise-induced hearing loss 
conducted from 1996-2015 (i.e., Finneran, 2015). For study-specific 
citations, please see that work. Anthropogenic sounds cover a broad 
range of frequencies and sound levels and can have a range of highly 
variable impacts on marine life, from none or minor to potentially 
severe responses, depending on received levels, duration of exposure, 
behavioral context, and various other factors. The potential effects of 
underwater sound from active acoustic sources can potentially result in 
one or more of the following: Temporary or permanent hearing 
impairment, non-auditory physical or physiological effects, behavioral 
disturbance, stress, and masking (Richardson et al., 1995; Gordon et 
al., 2004; Nowacek et al., 2007; Southall et al., 2007; G[ouml]tz et 
al., 2009). The degree of effect is intrinsically related to the signal 
characteristics, received level, distance from the source, and duration 
of the sound exposure. In general, sudden, high level sounds can cause 
hearing loss, as can longer exposures to lower level sounds. Temporary 
or permanent loss of hearing will occur almost exclusively for noise 
within an animal's hearing range. We first describe specific 
manifestations of acoustic effects before providing discussion specific 
to pile driving activities.
    Richardson et al. (1995) described zones of increasing intensity of 
effect that might be expected to occur, in relation to distance from a 
source and assuming that the signal is within an animal's hearing 
range. First is the area within which the acoustic signal would be 
audible (potentially perceived) to the animal but not strong enough to 
elicit any overt behavioral or physiological response. The next zone 
corresponds with the area where the signal is audible to the animal and 
of sufficient intensity to elicit behavioral or physiological 
responsiveness. Third is a zone within which, for signals of high 
intensity, the received level is sufficient to potentially cause 
discomfort or tissue damage to auditory or other systems. Overlaying 
these zones to a certain extent is the area within which masking (i.e., 
when a sound interferes with or masks the ability of an animal to 
detect a signal of interest that is above the absolute hearing 
threshold) may occur; the

[[Page 44873]]

masking zone may be highly variable in size.
    We describe the more severe effects (i.e., certain non-auditory 
physical or physiological effects) only briefly as we do not expect 
that there is a reasonable likelihood that pile driving may result in 
such effects (see below for further discussion). Potential effects from 
explosive impulsive sound sources can range in severity from effects 
such as behavioral disturbance or tactile perception to physical 
discomfort, slight injury of the internal organs and the auditory 
system, or mortality (Yelverton et al., 1973). Non-auditory 
physiological effects or injuries that theoretically might occur in 
marine mammals exposed to high level underwater sound or as a secondary 
effect of extreme behavioral reactions (e.g., change in dive profile as 
a result of an avoidance reaction) caused by exposure to sound include 
neurological effects, bubble formation, resonance effects, and other 
types of organ or tissue damage (Cox et al., 2006; Southall et al., 
2007; Zimmer and Tyack, 2007). The construction activities considered 
here do not involve the use of devices such as explosives or mid-
frequency tactical sonar that are associated with these types of 
effects.
    Threshold Shift--Marine mammals exposed to high-intensity sound, or 
to lower-intensity sound for prolonged periods, can experience hearing 
threshold shift (TS), which is the loss of hearing sensitivity at 
certain frequency ranges (Finneran, 2015). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not fully recoverable, 
or temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Repeated sound exposure that 
leads to TTS could cause PTS. In severe cases of PTS, there can be 
total or partial deafness, while in most cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to 
constitute auditory injury.
    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 (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse 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). 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.
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). 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. Few data 
on sound levels and durations necessary to elicit mild TTS have been 
obtained for marine mammals.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. 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. 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 occurs during a time 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.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise, and Yangtze finless porpoise (Neophocoena 
asiaeorientalis)) and three species of pinnipeds (northern elephant 
seal, harbor seal, and California sea lion) exposed to a limited number 
of sound sources (i.e., mostly tones and octave-band noise) in 
laboratory settings (Finneran, 2015). TTS was not observed in trained 
spotted (Phoca largha) and ringed (Pusa hispida) seals exposed to 
impulsive noise at levels matching previous predictions of TTS onset 
(Reichmuth et al., 2016). In general, harbor seals and harbor porpoises 
have a lower TTS onset than other measured pinniped or cetacean species 
(Finneran, 2015). Additionally, the existing marine mammal TTS data 
come from a limited number of individuals within these species. There 
are no data available on noise-induced hearing loss for mysticetes. For 
summaries of data on TTS in marine mammals or for further discussion of 
TTS onset thresholds, please see Southall et al. (2007), Finneran and 
Jenkins (2012), Finneran (2015), and NMFS (2018).
    Behavioral Effects--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 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., 2003; Southall et al., 2007; 
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not 
only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al., 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review 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., 2003). 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

[[Page 44874]]

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, behavioral state 
may affect the type of response. For example, animals that are resting 
may show greater behavioral change in response to disturbing sound 
levels than animals that are highly motivated to remain in an area for 
feeding (Richardson et al., 1995; NRC, 2003; Wartzok et al., 2003). 
Controlled experiments with captive marine mammals 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 airguns or acoustic harassment devices) have been varied but 
often consist of avoidance behavior or other behavioral changes 
suggesting discomfort (Morton and Symonds, 2002; see also Richardson et 
al., 1995; Nowacek et al., 2007). However, many delphinids approach 
low-frequency airgun source vessels with no apparent discomfort or 
obvious behavioral change (e.g., Barkaszi et al., 2012), indicating the 
importance of frequency output in relation to the species' hearing 
sensitivity.
    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.
    Variations in respiration naturally vary 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; Foote et al., 2004), while right whales 
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 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from airgun 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). 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 
(Evans and England, 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

[[Page 44875]]

critical behaviors such as foraging or resting). These effects have 
generally not been demonstrated for marine mammals, but studies 
involving fish 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 et al., 1996). However, Ridgway et al. (2006) 
reported that increased vigilance in bottlenose dolphins exposed to 
sound over a five-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., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
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, 2003).
    Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995; Erbe et al., 
2016). Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher intensity, and may occur whether the sound is natural (e.g., 
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g., 
shipping, sonar, seismic exploration) in origin. The ability of a noise 
source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-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.
    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 man-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, 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 through other compensatory behaviors 
(Houser and Moore, 2014). Masking can be tested directly in captive 
species (e.g., Erbe, 2008), but in wild populations it must

[[Page 44876]]

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).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand, 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with pile driving 
that have the potential to cause behavioral harassment, depending on 
their distance from pile driving activities. Airborne noise would 
primarily be an issue for pinnipeds that are swimming near the project 
site within the range of noise levels elevated above the acoustic 
criteria. We recognize that pinnipeds in the water could be exposed to 
airborne sound that may result in behavioral harassment when looking 
with their heads above water. Most likely, airborne sound would cause 
behavioral responses similar to those discussed above in relation to 
underwater sound. For instance, anthropogenic sound could cause hauled 
out pinnipeds to exhibit changes in their normal behavior, such as 
reduction in vocalizations, or cause them to temporarily abandon the 
area and move further from the source. However, these animals would 
previously have been `taken' because of exposure to underwater sound 
above the behavioral harassment thresholds, which are in all cases 
larger than those associated with airborne sound. Thus, the behavioral 
harassment of these animals is already accounted for in these estimates 
of potential take. Therefore, we do not believe that authorization of 
incidental take resulting from airborne sound for pinnipeds is 
warranted, and airborne sound is not discussed further here.
    Potential Effects of the Corps' Proposed Activity--As described 
previously (see ``Description of Active Acoustic Sound Sources''), the 
Corps proposes to conduct impact and vibratory driving. The effects of 
pile driving on marine mammals are dependent on several factors, 
including the size, type, and depth of the animal; the depth, 
intensity, and duration of the pile driving sound; the depth of the 
water column; the substrate of the habitat; the standoff distance 
between the pile and the animal; and the sound propagation properties 
of the environment. With both types, it is likely that the pile driving 
could result in temporary, short term changes in an animal's typical 
behavioral patterns and/or avoidance of the affected area. These 
behavioral changes may include (Richardson et al., 1995): Changing 
durations of surfacing and dives; moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior; avoidance of areas where sound sources 
are located; and/or flight responses.
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be expected to be biologically significant if the 
change affects growth, survival, or reproduction. Significant 
behavioral modifications that could lead to effects on growth, 
survival, or reproduction, such as drastic changes in diving/surfacing 
patterns or significant habitat abandonment are extremely unlikely in 
this area (i.e., relatively shallow waters in an area with considerable 
vessel traffic).
    Whether impact or vibratory driving, sound sources would be active 
for relatively short durations, with relation to potential for masking. 
The frequencies output by pile driving activity are lower than those 
used by most species expected to be regularly present for communication 
or foraging. We expect insignificant impacts from masking, and any 
masking event that could possibly rise to Level B harassment under the 
MMPA would occur concurrently within the zones of behavioral harassment 
already estimated for vibratory and impact pile driving, and which have 
already been taken into account in the exposure analysis.

Anticipated Effects on Marine Mammal Habitat

    The proposed activities may have potential short-term impacts to 
food sources such as forage fish. The proposed activities could also 
affect acoustic habitat (see masking discussion above), but meaningful 
impacts are unlikely. There are no known foraging hotspots, or other 
ocean bottom structures of significant biological importance to marine 
mammals present in the waters in the vicinity of the multiple king pile 
marker sites. Therefore, the main impact issue associated with the 
proposed activity would be temporarily elevated sound levels and the 
associated direct effects on marine mammals, as discussed previously. 
The most likely impact to marine mammal habitat occurs from pile 
driving effects on likely marine mammal prey (i.e., fish) near where 
the piles are installed. Impacts to the immediate substrate during 
installation of piles would be minor since piles would be driven 
through existing enrockment structures. This could result in limited, 
temporary suspension of sediments, which could impact water quality and 
visibility for a short amount of time, but which would not be expected 
to have any effects on individual marine mammals. Impacts to substrate 
are therefore not discussed further.
    Effects to Prey--Sound may affect marine mammals through impacts on 
the abundance, behavior, or distribution of prey species (e.g., 
crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies 
by species, season, and location and, for some, is not well documented. 
Here, we describe studies regarding the effects of noise on known 
marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick 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 which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation

[[Page 44877]]

(e.g., feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving on fish, although several are 
based on studies in support of large, multiyear bridge construction 
projects (e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 
2009). Several studies have demonstrated that impulse sounds might 
affect the distribution and behavior of some fishes, potentially 
impacting foraging opportunities or increasing energetic costs (e.g., 
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 
1992; Santulli et al., 1999; Paxton et al., 2017). However, some 
studies have shown no or slight reaction to impulse sounds (e.g., Pena 
et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott 
et al., 2012). More commonly, though, the impacts of noise on fish are 
temporary.
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al., 2012b; Casper et al., 2013).
    The most likely impact to fish from pile driving activities at the 
project areas would be temporary behavioral avoidance of the area. The 
duration of fish avoidance of an area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution and 
behavior is anticipated. In general, impacts to marine mammal prey 
species are expected to be minor and temporary due to the expected 
short daily duration of individual pile driving events at each king 
pile marker location and the relatively small areas being affected.
    In summary, given the short duration of sound (up to 90 minutes) 
associated with individual pile driving events and the small area being 
affected relative to available nearby habitat, pile driving activities 
associated with the proposed action are not likely to have a permanent, 
adverse effect on any fish habitat, or populations of fish species or 
other prey. Thus, we conclude that impacts of the specified activity 
are not likely to have more than short-term adverse effects on any prey 
habitat or populations of prey species. Further, any impacts to marine 
mammal habitat are not expected to result in significant or long-term 
consequences for individual marine mammals, or to contribute to adverse 
impacts on their populations.
    The area impacted by the project is relatively small compared to 
the available habitat in the lower Columbia River and Columbia River 
estuary. Any behavioral avoidance by fish of the disturbed area would 
still leave significantly large areas of fish and marine mammal 
foraging habitat in the nearby vicinity. As described in the preceding, 
the potential for the Corps' construction to affect the availability of 
prey to marine mammals or to meaningfully impact the quality of 
physical or acoustic habitat is considered to be insignificant. 
Furthermore, impact driving will only take place in November, as per 
the 2012 SLOPES IV programmatic biological opinion to protect 17 fish 
species, including multiple salmon species. Effects to habitat will not 
be discussed further in this document.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers'' and the negligible impact 
determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, 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 pile driving. Based on the nature of the 
activity and the anticipated effectiveness of the mitigation measures 
(i.e., use of bubble curtains during impact driving, establishment of 
shutdown zones--discussed in detail below in Proposed Mitigation 
section, Level A harassment is neither anticipated nor proposed to be 
authorized.
    As described previously, no mortality is anticipated or proposed to 
be authorized for this activity. Below we describe how the take is 
estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of takes, additional information that can qualitatively 
inform take estimates is also sometimes available (e.g., previous 
monitoring results or average group size). Below, we describe the 
factors considered here in more detail and present the proposed take 
estimate.

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals would be reasonably expected to be 
behaviorally harassed (equated to Level B harassment) or to incur PTS 
of some degree (equated to Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g., 
vibratory pile-

[[Page 44878]]

driving, drilling) and above 160 dB re 1 [mu]Pa (rms) for non-explosive 
impulsive (e.g., seismic airguns) or intermittent (e.g., scientific 
sonar) sources.
    The Corps' proposed activity includes the use of continuous 
(vibratory pile driving) and impulsive (impact pile driving) sources, 
and therefore the 120 and 160 dB re 1 [mu]Pa (rms) are applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). The Corp's proposed activity includes the 
use of impulsive (impact pile driving) and non-impulsive (vibratory 
pile driving) source.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--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[micro]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 will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.

Sound Propagation

    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:

B = transmission loss coefficient (assumed to be 15)
R1 = the distance of the modeled SPL from the driven 
pile, and
R2 = the distance from the driven pile of the initial 
measurement.

    This formula neglects loss due to scattering and absorption, which 
is assumed to be zero here. The degree to which underwater sound 
propagates away from a sound source is dependent on a variety of 
factors, most notably the water bathymetry and presence or absence of 
reflective or absorptive conditions including in-water structures and 
sediments. Spherical spreading occurs in a perfectly unobstructed 
(free-field) environment not limited by depth or water surface, 
resulting in a 6 dB reduction in sound level for each doubling of 
distance from the source (20 * log(range)). Cylindrical spreading 
occurs in an environment in which sound propagation is bounded by the 
water surface and sea bottom, resulting in a reduction of 3 dB in sound 
level for each doubling of distance from the source (10 * log(range)). 
As is common practice in coastal waters, here we assume practical 
spreading loss (4.5 dB reduction in sound level for each doubling of 
distance). Practical spreading is a compromise that is often used under 
conditions where water depth increases as the receiver moves away from 
the shoreline, resulting in an expected propagation environment that 
would lie between spherical and cylindrical spreading loss conditions.

Sound Source Levels

    The intensity of pile driving sounds is greatly influenced by 
factors such as the type of piles, hammers, and the physical 
environment in which the activity takes place. Pile driving may be done 
with either vibratory or impact hammer, with vibratory driving being 
the preferred method. Due to anticipated enrockment surrounding 
existing piles, however, use of impact hammers may be required.
    Estimated in-water sound levels anticipated from vibratory 
installation and impact hammer installation of steel pipe piles are 
summarized in Table 4. Sound pressure levels for impact driving of 24-
in steel piles were taken from Caltrans (2015). The SLs in the table 
below include a 7 dB reduction for impact driving due to attenuation 
associated with the use of bubble curtains. Vibratory driving source 
levels for 24-in steel piles came from the United States Navy (2015). 
Due to the short operating window (61 days), and concerns about 
possible delays due to bad weather, the Corps does not propose to use 
bubble curtains during vibratory driving. This should expedite pile 
installation at king pile locations where use of vibratory hammers is 
employed.

[[Page 44879]]



    Table 4--Estimated Underwater Source Levels Associated With Vibratory Pile Driving and Impact Hammer Pile
                                                     Driving
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
Pile type                                           Sound Pressure Level (SPL) (single strike)
----------------------------------------------------------------------------------------------------------------
24-Inch Steel Pipe Piles w/      200 dBPEAK................  187 dBRMS.................  171 dBSEL.
 impact hammer (attenuated) \1\.
24-Inch Steel Pipe Piles w/      Not Available.............  161 dBRMS.................  Not Available.
 vibratory (unattenuated) \2\.
----------------------------------------------------------------------------------------------------------------
\1\ From Caltrans (2015) Acoustic data from CalTrans 2015 Table I.2-1. Summary of Near-Source (10-Meter)
  Unattenuated Sound Pressure Levels for In-Water Pile Driving Using an Impact Hammer: 0.61-meter (24-inch)
  steel pipe pile in water ~15 meters deep, w/7dB reduction for use of attenuation (as per NMFS 2019 pers.
  Comm).
\2\ From United States Navy. 2015. Proxy source sound levels and potential bubble curtain attenuation for
  acoustic modeling of nearshore marine pile driving at Navy installations in Puget Sound. Prepared by Michael
  Slater, Naval Surface Warfare Center, Carderock Division, and Sharon Rainsberry, Naval Facilities Engineering
  Command Northwest. Revised January 2015. Table 2-2.

    When the NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimate of Level A harassment take. However, these tools offer the 
best way to predict appropriate isopleths when more sophisticated 3D 
modeling methods are not available, and NMFS continues to develop ways 
to quantitatively refine these tools, and will qualitatively address 
the output where appropriate. For stationary sources such as pile 
driving, NMFS User Spreadsheet predicts the distance at which, if a 
marine mammal remained at that distance the whole duration of the 
activity, it would incur PTS. Inputs used in the User Spreadsheet, and 
the resulting Level A harassment isopleths are reported below in Tables 
5 and 6 respectively. Note that while up to 9 piles could be installed 
in a single day, they would be driven at different locations and the 
ensonified areas associated with each location would not overlap. For 
the purpose of calculating PTS isopleths using the User Spreadsheet, it 
is assumed that a single pile would be driven per day at a single 
location (i.e., the zones for each pile are calculated independently) 
since there will be no overlap of disturbance zones from adjacent king 
pile installation sites. The Level B harassment isopleths were 
calculated using the practical spreading loss model. Underwater noise 
will fall below the behavioral effects threshold of 160 dB for impact 
driving and 120 dB rms for vibratory driving at the distances shown in 
Table 6.

    Table 5--NMFS Technical Guidance (2018) User Spreadsheet Input To
                         Calculate PTS Isopleths
------------------------------------------------------------------------
                                                          24-in Steel
             Inputs               24-in Steel impact       vibratory
                                     installation        installation
------------------------------------------------------------------------
Spreadsheet Tab Used............  (E.1) Impact Pile   (A.1) Vibratory
                                   Driving.            Pile Driving.
Source Level (Single Strike/shot  171 dB SEL/200 dB   161 dB RMS.
 SEL).                             Peak.
Weighting Factor Adjustment       2.................  2.5.
 (kHz).
Number of strikes per pile......  550...............
Number of piles per day.........  1.................  1.
Duration to install single pile   60................  30.
 (minutes).
Propagation (xLogR).............  15................  15.
Distance of source level          10................  10.
 measurement (meters) +.
------------------------------------------------------------------------


                                Table 6--Level A and Level B Harassment Isopleths
----------------------------------------------------------------------------------------------------------------
                                                             Level A harassment              Level B harassment
                                                  --------------------------------------------------------------
                                                       Permanent Threshold Shift (PTS)       Isopleth (meters)
              Noise generation type                           isopleth (meters)           ----------------------
                                                  ----------------------------------------
                                                     Phocid pinniped    Otariid pinniped         All groups
----------------------------------------------------------------------------------------------------------------
24'' Steel Pipe Impact attenuated................               56.9                 4.1                    631
24'' Steel Pipe Vibratory unattenuated...........                2.6                 0.2                  5,412
----------------------------------------------------------------------------------------------------------------

    The Corps and NMFS do not anticipate take of marine mammals by 
Level A harassment due to the relatively small PTS isopleths as well as 
required shutdown if an animal approaches the zone. The Level B 
harassment zone area for each king pile site will differ since the 
landforms and river morphology are unique to each king pile location.

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. Pinnipeds are typically concentrated at haul out sites 
(e.g., the MCR South jetty) and feeding areas where there are 
concentrations of salmon (e.g., Bonneville Dam). Individual animals 
that occur near king pile locations are likely to be in transit between 
these two prominent sites. Pinnipeds that travel to Bonneville Dam 
consistently forage in all three of the dam's tailraces. A tailrace is 
the flume, or water channel leading away from the dam. Pinniped 
presence at the dam during the spring

[[Page 44880]]

months has been recorded since 2002 and during fall/winter months 
starting in 2011 to assess the impact of predation on adult salmonids 
and other fish (Tidwell et al. 2019).
    Estimated take was calculated using the maximum daily number of 
individuals observed at Bonneville dam (Tidwell et al. 2019), 
multiplied by the total number of work days (61). The maximum daily 
number of animals observed at the dam between August 15 and December 31 
was used for both California sea lions (3 in 2015 and 2017) and Steller 
sea lions (56 in 2016). No harbor seals were observed during the fall/
winter sampling period. However, only one of the three tailraces was 
monitored during the fall/winter months and only when sea lion 
abundance was >=20 animals. Therefore, NMFS multiplied the number of 
observed California and Steller sea lions by three to account for 
potential animals at all of the tailraces. Since there were no harbor 
seals observed during the fall/winter period, NMFS used the maximum 
daily observation from the spring observation period (3 in 2006) during 
which all three tailraces were monitored. These estimates assume that 
if an animal transits the reach of river where driving takes place it 
will pass through the Level B isopleth since in most cases the radius 
would be larger than the width of the river in most cases. Table 7 
depicts the stocks NMFS proposes to authorize for take, the numbers 
proposed for authorization, and the percentage of the stock taken.

                   Table 7--Level B Harassment Take Estimates for the King Pile Marker Project
----------------------------------------------------------------------------------------------------------------
                                                                                                  Percentage of
                           Species                               Level B take   Stock abundance    stock taken
----------------------------------------------------------------------------------------------------------------
California Sea Lion..........................................              549          296,750              0.2
Stellar Sea Lion.............................................           10,248           41,638             24.6
Harbor Seal..................................................              183         * 24,732              0.7
----------------------------------------------------------------------------------------------------------------
* There is no current estimate of abundance available for this stock since most recent abundance estimate is >8
  years old. Abundance value provided represents best available information from 1999.

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses (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 such 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned), and;
    (2) the practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    In addition to the measures described later in this section, the 
Corps must employ the following standard mitigation measures:
     Conduct briefings between construction supervisors and 
crews and the marine mammal monitoring team prior to the start of all 
pile driving activity, and when new personnel join the work, to explain 
responsibilities, communication procedures, marine mammal monitoring 
protocol, and operational procedures;
     For in-water heavy machinery work other than pile driving 
(e.g., standard barges, tug boats), if a marine mammal comes within 10 
m, operations shall cease and vessels shall reduce speed to the minimum 
level required to maintain steerage and safe working conditions. This 
type of work could include the following activities: (1) Movement of 
the barge to the pile location; or (2) positioning of the pile on the 
substrate via a crane (i.e., stabbing the pile);
     Work may only occur during daylight hours, when visual 
monitoring of marine mammals can be conducted;
     For any marine mammal species for which take by Level B 
harassment has not been requested or authorized, in-water pile 
installation will shut down immediately when the animals are sighted;
     If take by Level B harassment reaches the authorized limit 
for an authorized species, pile installation will be stopped as these 
species approach the Level B harassment zone to avoid additional take 
of them.
    Establishment of Shutdown Zones--For all pile driving activities, 
the Corps establish a shutdown zone. The purpose of a shutdown zone is 
generally to define an area within which shutdown of activity would 
occur upon sighting of a marine mammal (or in anticipation of an animal 
entering the defined area). Shutdown zones will vary based on the type 
of driving activity and by marine mammal hearing group. Shutdown zones 
during impact and vibratory driving will be 10 m for all species, with 
the exception of a 60-m shutdown zone for harbor seals during impact 
driving activities. In all cases, the proposed shutdown zones are 
larger than the calculated Level A harassment isopleths shown in Table 
6. The placement of protected species observers (PSOs) during all pile 
driving activities (described in detail in the Proposed Monitoring and 
Reporting Section) will ensure that the entirety of all shutdown zones 
are visible during pile installation.
    Establishment of Monitoring Zones for Level B Harassment--The Corps 
will establish monitoring zones, based on the Level B harassment 
isopleths which are

[[Page 44881]]

areas where SPLs are equal to or exceed the 160 dB rms threshold for 
impact driving and the 120 dB rms threshold during vibratory driving. 
Monitoring zones provide utility for observing by establishing 
monitoring protocols for areas adjacent to the shutdown zones. 
Monitoring zones enable observers to be aware of and communicate the 
presence of marine mammals in the project area outside the shutdown 
zone and thus prepare for a potential cease of activity should the 
animal enter the shutdown zone. In the unlikely event that a cetacean 
enters the Level B harassment zones work will stop immediately until 
the animal either departs the zone or is undetected for 15 minutes. 
Distances to the Level B harassment zones are depicted in Table 6. In 
addition, the Corps will establish minimum allowable work distances 
between adjacent work platforms, based on monitoring zone isopleths, to 
ensure that there is no overlap of behavioral harassment zones.
    Sound Attenuation--Bubble curtains will be used during any impact 
pile driving of piles located in water greater than 2 ft. in depth. The 
bubble curtain will be operated in a manner consistent with the 
following performance standards:
    a. The bubble curtain will distribute air bubbles around 100 
percent of the piling perimeter for the full depth of the water column;
    b. The lowest bubble ring will be in contact with the mudline for 
the full circumference of the ring, and the weights attached to the 
bottom ring shall ensure 100 percent mudline contact. No parts of the 
ring or other objects shall prevent full mudline contact; and
    c. Air flow to the bubblers must be balanced around the 
circumference of the pile.
    Soft Start--The use of a soft-start procedure are believed to 
provide additional protection to marine mammals by providing warning 
and/or giving marine mammals a chance to leave the area prior to the 
hammer operating at full capacity. For impact pile driving, contractors 
will be required to provide an initial set of strikes from the hammer 
at reduced percent energy, each strike followed by no less than a 30-
second waiting period. This procedure will be conducted a total of 
three times before impact pile driving begins. Soft start is not 
required during vibratory pile driving activities. A soft start must be 
implemented at the start of each day's impact pile driving and at any 
time following cessation of impact pile driving for a period of thirty 
minutes or longer. If a marine mammal is present within the shutdown 
zone, soft start will be delayed until the animal is observed leaving 
the shutdown zone. Soft start will begin only after the PSO has 
determined, through sighting, that the animal has moved outside the 
shutdown zone or 15 minutes have passed without being seen in the zone. 
If a marine mammal is present in the Level B harassment zone, soft 
start may begin and a Level B take will be recorded for authorized 
species. Soft start up may occur whether animals enter the Level B zone 
from the shutdown zone or from outside the monitoring area.
    Pre-Activity Monitoring--Prior to the start of daily in-water 
construction activity, or whenever a break in pile driving of 30 
minutes or longer occurs, PSOs will observe the shutdown and monitoring 
zones for a period of 30 minutes. The shutdown zone will be cleared 
when a marine mammal has not been observed within the zone for that 30-
minute period. If a marine mammal is observed within the shutdown zone, 
a soft-start cannot proceed until the animal has left the zone or has 
not been observed for 15 minutes. If the Level B harassment zone has 
been observed for 30 minutes and marine mammals are not present within 
the zone, soft start procedures can commence and work can continue even 
if visibility becomes impaired within the Level B harassment zone. When 
a marine mammal permitted for take by Level B harassment is present in 
the Level B harassment zone, pile driving activities may begin and take 
by Level B will be recorded. As stated above, if the entire Level B 
harassment zone is not visible at the start of construction, pile 
driving activities can begin. If work ceases for more than 30 minutes, 
the pre-activity monitoring of both the Level B harassment and shutdown 
zone will commence.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means effecting the least practicable impact on the 
affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present in the 
proposed action area. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Visual Monitoring

    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after pile driving activities. In addition, observers shall 
record all incidents of marine mammal occurrence, regardless of 
distance from activity, and shall document any behavioral reactions in 
concert with distance from piles being driven. Pile driving activities 
include the time to install a single pile or series of piles, as long 
as the time elapsed between uses of the pile driving equipment is no 
more than thirty minutes.
    There will be at least one PSO employed at all king pile 
installation locations during all pile driving activities. PSO will not 
perform duties

[[Page 44882]]

for more than 12 hours in a 24-hour period. The PSO would be positioned 
close to pile driving activities at the best practical vantage point.
    As part of monitoring, PSOs would scan the waters using binoculars, 
and/or spotting scopes, and would use a handheld GPS or range-finder 
device to verify the distance to each sighting from the project site. 
All PSOs would be trained in marine mammal identification and behaviors 
and are required to have no other project-related tasks while 
conducting monitoring. In addition, PSOs will monitor for marine 
mammals and implement shutdown/delay procedures when applicable by 
calling for the shutdown to the hammer operator. Qualified observers 
are trained and/or experienced professionals, with the following 
minimum qualifications:
     Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target;
     Independent observers (i.e., not construction personnel);
     Observers must have their CVs/resumes submitted to and 
approved by NMFS;
     Advanced education in biological science or related field 
(i.e., undergraduate degree or higher). Observers may substitute 
education or training for experience;
     Experience and ability to conduct field observations and 
collect data according to assigned protocols (this may include academic 
experience);
     At least one observer must have prior experience working 
as an observer;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates and times when in-water construction 
activities were suspended to avoid potential incidental injury from 
construction sound of marine mammals observed within a defined shutdown 
zone; and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.

Reporting

    A draft marine mammal monitoring report must be submitted to NMFS 
within 90 days after the completion of pile driving activities. This 
reports will include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the reports must include:
     Date and time that monitored activity begins or ends;
     Construction activities occurring during each observation 
period;
     Weather parameters (e.g., percent cover, visibility);
     Water conditions (e.g., sea state, tide state);
     Species, numbers, and, if possible, sex and age class of 
marine mammals;
     Description of any observable marine mammal behavior 
patterns, including bearing and direction of travel and distance from 
pile driving activity;
     Distance from pile driving activities to marine mammals 
and distance from the marine mammals to the observation point;
     Locations of all marine mammal observations;
     An estimate of total take based on proportion of the 
monitoring zone that was observed; and
     Other human activity in the area.
    If no comments are received from NMFS within 30 days, that phase's 
draft final report will constitute the final report. If comments are 
received, a final report for the given phase addressing NMFS comments 
must be submitted within 30 days after receipt of comments. In the 
unanticipated event that the specified activity clearly causes the take 
of a marine mammal in a manner prohibited by the IHAs (if issued), such 
as an injury, serious injury or mortality, the Corps would immediately 
cease the specified activities and report the incident to the Chief of 
the Permits and Conservation Division, Office of Protected Resources, 
NMFS, and the West Coast Regional Stranding Coordinator. The report 
would include the following information:
     Description of the incident;
     Environmental conditions (e.g., Beaufort sea state, 
visibility);
     Description of all marine mammal observations in the 24 
hours preceding the incident;
     Species identification or description of the animal(s) 
involved;
     Fate of the animal(s); and
     Photographs or video footage of the animal(s) (if 
equipment is available).
    Activities would not resume until NMFS is able to review the 
circumstances of the prohibited take. NMFS would work with the Corps to 
determine what is necessary to minimize the likelihood of further 
prohibited take and ensure MMPA compliance. The Corps would not be able 
to resume their activities until notified by NMFS via letter, email, or 
telephone.
    In the event that the Corps discovers an injured or dead marine 
mammal, and the lead PSO determines that the cause of the injury or 
death is unknown and the death is relatively recent (e.g., in less than 
a moderate state of decomposition as described in the next paragraph), 
the Corps would immediately report the incident to the Chief of the 
Permits and Conservation Division, Office of Protected Resources, NMFS, 
and the West Coast Regional Stranding Coordinator. The report would 
include the same information identified in the paragraph above. 
Activities would be able to continue while NMFS reviews the 
circumstances of the incident. NMFS would work with the Corps to 
determine whether modifications in the activities are appropriate.
    In the event that the Corps discovers an injured or dead marine 
mammal and the lead PSO determines that the injury or death is not 
associated with or related to the activities authorized in these IHAs 
(e.g., previously wounded animal, carcass with moderate to advanced 
decomposition, or scavenger damage), the Corps would report the 
incident to the Chief of the Permits and Conservation Division, Office 
of Protected Resources, NMFS, and the West Coast Regional Stranding 
Coordinator, within 24 hours of the discovery. The Corps would provide 
photographs, video footage (if available), or other documentation of 
the stranded animal sighting to NMFS and the Marine Mammal Stranding 
Network.

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

[[Page 44883]]

considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    To avoid repetition, our analysis applies to all species listed in 
Table 7, given that NMFS expects the anticipated effects of the 
proposed pile driving to be similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, NMFS has identified species-specific factors to 
inform the analysis.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of the Corps' proposed activity. As stated in the 
proposed mitigation section, shutdown zones will be established and 
monitored that equal or exceed calculated Level A harassment isopleths 
during all pile driving activities.
    Behavioral responses of marine mammals to pile driving during the 
King Pile Marker Project are expected to be mild, short term, and 
temporary. Marine mammals within the Level B harassment zones may not 
show any visual cues they are disturbed by activities or they could 
become alert, avoid the area, leave the area, or display other mild 
responses that are not observable such as changes in vocalization 
patterns. Given the short duration of noise-generating activities (less 
than 90 minutes of combined daily impact and vibratory driving at 68 
separate locations over 61 days, any harassment would be likely be 
intermittent and temporary.
    In addition, for all species there are no known biologically 
important areas (BIAs) within the lower Columbia River and no ESA-
designated marine mammal critical habitat. The lower Columbia River 
represents a very small portion of the total habitat available to the 
pinniped species for which NMFS is proposing to authorize take. More 
generally, there are no known calving or rookery grounds within the 
project area, the project area represents a small portion of available 
foraging habitat, and the duration of noise-producing activities 
relatively is short, meaning impacts on marine mammal feeding for all 
species should be minimal.
    Any impacts on marine mammal prey that would occur during the 
Corps' proposed activity would have at most short-terms effects on 
foraging of individual marine mammals while transiting between the 
South Jetty at the Mouth of the Columbia River and Bonneville Dam 
located 146 miles upstream. Better feeding opportunities exist at these 
two locations which is why pinnipeds tend to congregate in these areas. 
Therefore, indirect effects on marine mammal prey during the 
construction are not expected to be substantial, and these 
insubstantial effects would therefore be unlikely to cause substantial 
effects on individual marine mammals or the populations of marine 
mammals as a whole.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     The Corps would implement mitigation measures including 
bubble curtains and soft-starts during impact pile driving as well as 
shutdown zones that exceed Level A harassment zones for authorized 
species, such that Level A harassment is neither anticipated nor 
authorized;
     Anticipated incidents of Level B harassment consist of, at 
worst, temporary modifications in behavior;
     There are no BIAs or other known areas of particular 
biological importance to any of the affected stocks impacted by the 
activity within the Columbia River estuary or lower Columbia River;
     The project area represents a very small portion of the 
available foraging area for all marine mammal species and anticipated 
habitat impacts are minimal; and
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under 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. Additionally, other qualitative 
factors may be considered in the analysis, such as the temporal or 
spatial scale of the activities.
    Table 7 in the Marine Mammal Occurrence and Take Calculation and 
Estimation section presents the number of animals that could be exposed 
to received noise levels that may result in take by Level B harassment 
from the Corps' proposed activities. Our analysis shows that less than 
25 percent of the Steller sea lion stock could be taken. Less than one 
percent of California sea lion and harbor seal stocks are expected to 
be taken. Given that numbers for Steller sea lions were derived from 
limited observation at Bonneville Dam, it is likely that many of these 
takes will be repeated takes of the same animals over multiple days. As 
such, the take estimate serves as a good estimate of instances of take, 
but is likely an overestimate of individuals taken, so actual 
percentage of stocks taken would be even lower. We also emphasize the 
fact that the lower Columbia River represents a very small portion of 
the stock's large range, which extends from southeast Alaska to 
southern California. It is unlikely that one quarter of the entire 
stock would travel in excess of 137 miles upstream to forage at 
Bonneville Dam on the Columbia River.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population size 
of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action.

[[Page 44884]]

Endangered Species Act (ESA)

    No incidental take of ESA-listed species is proposed for 
authorization or expected to result from this activity. Therefore, NMFS 
has determined that formal consultation under section 7 of the ESA is 
not required for this action.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to the Corps for conducting pile driving activities on the 
Columbia River between September 15 and November 30, 2019, 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 proposed 
[action]. We also request at this time comment on the potential renewal 
of this proposed IHA as described in the paragraph below. Please 
include with your comments any supporting data or literature citations 
to help inform decisions on the request for this IHA or a subsequent 
Renewal.
    On a case-by-case basis, NMFS may issue a one-year IHA renewal with 
an additional 15 days for public comments when (1) another year of 
identical or nearly identical activities as described in the Specified 
Activities section of this notice is planned or (2) the activities as 
described in the Specified Activities 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 expiration of the current IHA.
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal 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 
because only a subset of the initially analyzed activities remain to be 
completed under the Renewal).
    (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: August 20, 2019.
Cathryn E. Tortorici,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2019-18351 Filed 8-26-19; 8:45 am]
BILLING CODE 3510-22-P