Notice2026-08153
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to U.S. Army Corps of Engineers Miller Sands Island, Rice Island, and Cottonwood Island Pile Dike Repairs Projects on the Lower Columbia River in Oregon and Washington
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
April 27, 2026
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from U.S. Army Corps of Engineers (USACE) for authorization to take marine mammals incidental to the Miller Sands-Rice Island Pile Dike Repairs Project (MSRI Project) and Cottonwood Island Pile Dike Replacement Project (CI Project) on the lower Columbia River (LCR) in Oregon and Washington. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue two incidental harassment authorizations (IHAs) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on possible one-time, 1-year renewals 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.
Full Text
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<title>Federal Register, Volume 91 Issue 80 (Monday, April 27, 2026)</title>
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[Federal Register Volume 91, Number 80 (Monday, April 27, 2026)]
[Notices]
[Pages 22498-22525]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-08153]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XF657]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to U.S. Army Corps of Engineers Miller
Sands Island, Rice Island, and Cottonwood Island Pile Dike Repairs
Projects on the Lower Columbia River in Oregon and Washington
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorizations; request
for comments on proposed authorizations and possible renewals.
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SUMMARY: NMFS has received a request from U.S. Army Corps of Engineers
(USACE) for authorization to take marine mammals incidental to the
Miller Sands-Rice Island Pile Dike Repairs Project (MSRI Project) and
Cottonwood Island Pile Dike Replacement Project (CI Project) on the
lower Columbia River (LCR) in Oregon and Washington. Pursuant to the
Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its
proposal to issue two incidental harassment authorizations (IHAs) to
incidentally take marine mammals during the specified activities. NMFS
is also requesting comments on possible one-time, 1-year renewals 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 May 27,
2026.
ADDRESSES: Comments should be addressed to Permits and Conservation
Division, Office of Protected Resources, National Marine Fisheries
Service and should be submitted via email to <a href="/cdn-cgi/l/email-protection#b0f9e4e09ed4d5ddd1c2d5c3c4f0dedfd1d19ed7dfc6"><span class="__cf_email__" data-cfemail="450c11156b2120282437203631052b2a24246b222a33">[email protected]</span></a>.
Electronic
[[Page 22499]]
copies of the application and supporting documents, as well as a list
of the references cited in this document, may be obtained online at:
<a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act/incidental-take-authorizations-construction-activities</a>. In case of problems accessing these documents,
please call the contact listed below.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> 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: Austin Demarest, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et
seq.) directs the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking; other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (referred to as ``mitigation'');
and requirements pertaining to the monitoring and reporting of the
takings. The definitions of all applicable MMPA statutory terms used
above are included in the relevant sections below (see also 16 U.S.C.
1362; 50 CFR 216.3, 216.103).
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an IHA)
with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for NAO 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 IHAs 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 requests.
Summary of Request
On April 10, 2025, and May 9, 2025, NMFS received requests from
USACE for two IHAs to take marine mammals incidental to pile driving
(installation and removal) associated with construction to replace pile
dikes at Miller Sands-Rice Island and Cottonwood Island on the lower
Columbia River in Oregon and Washington. Following NMFS' review of each
original application and multiple revised versions, USACE submitted
revised versions for the MSRI Project and CI Project on March 9, 2026,
and March 12, 2026, respectively. NMFS subsequently deemed the
applications complete on March 26, 2026. USACE's request for the MSRI
Project is for take of harbor porpoises, Steller sea lions, California
sea lions, and harbor seals, by Level B harassment, and for a subset of
these species, by Level A harassment. For the CI Project, USACE's
request is for take of Steller sea lions, California sea lions, and
harbor seals, by Level A and Level B harassment. Neither USACE nor NMFS
expect serious injury or mortality to result from this activity and,
therefore, IHAs are appropriate.
Description of Proposed Activity
Overview
The USACE proposes repairing and replacing pile dikes for two
separate projects at different locations on the lower Columbia River
(LCR). The projects would restore flood control, prevent erosion,
maintain safe vessel passage, and reduce the frequency and need of
maintenance dredging in the LCR. The USACE MSRI Project would repair
and replace three existing pile dikes between river mile (RM) 23 and RM
25 near Altoona, Washington. The project includes removing debris and
degraded timber piles, enhancing or extending enrockment which would
replace three existing timber pile dikes, and connecting two of these
three pile dikes together (connector). After enrockment is in place,
eight steel Aid to Navigation (ATON) piles would be installed along the
enrockment to mark the new pile dikes and pile dike connector. In-water
construction is anticipated over 4 months between November 2026 through
February 2027 in Wahkiakum County, Washington, and Clatsop County,
Oregon.
The USACE CI Project would repair or replace 10 existing pile dikes
between RM 68 and RM 71 in the LCR, southeast and directly upstream of
Longview, Washington in Cowlitz County. The project would include
construction of new shore attachments for 5 pile dikes, installing new
steel marker piles at 10 pile dikes, enhancing or extending enrockment
in place of existing pile dikes, and construction of up to 3 material
offload facilities on Cottonwood Island. Construction for the CI
Project is expected to occur over 4 months from November 2026 through
February 2027. Activities from both projects that have the potential to
result in Level A harassment and Level B harassment of marine mammals
from underwater sound production include impact and vibratory pile
installation and vibratory pile removal.
Dates and Duration
Each of these proposed IHAs would be valid for the statutory
maximum of 1 year from the date of effectiveness. They would become
effective upon written notification from the applicant to NMFS, but not
beginning later than 1 year from the date of issuance or extending
beyond 2 years from the date of issuance.
The MSRI Project is scheduled to span 5 months, with pile driving
being restricted to a 4-month window between
[[Page 22500]]
November 2026 and March 2027. Debris and pile removal would require
approximately 15 days, while pile installation would take approximately
8 days; construction days may be non-consecutive.
The CI Project is scheduled to occur over 4 months, from November
2026 through February 2027. Permanent and temporary pile installation
or removal would take approximately 66 non-consecutive days. Activities
for both projects would occur during daylight hours, specifically from
30 minutes before civil dawn to 30 minutes after civil dusk.
Specific Geographic Region
The LCR flows 146 miles (mi) or 235 kilometers (km) from Bonneville
Dam to the Pacific Ocean. This reach of the river features a deep-draft
shipping channel supporting major ports and connects major cities and
towns in Oregon and Washington to the Pacific Ocean. The LCR serves as
an important migratory corridor for salmonids, sturgeon, and eulachon
(Thaleichthys pacificus) as they transition freshwater and marine life
stages, while providing foraging opportunities for pinnipeds and other
wildlife.
The Miller Rice pile dike system consists of seven Pile Dolphins
(PDs) located between Miller Sands Island and Rice Island, extending
from RM 22.75 to RM 24.63 in Wahkiakum County, Washington, and Clatsop
County, Oregon (figure 1). The structures are identified by their RM
location: PDs 22.75, 23.07, 23.39, 23.67, 23.71, 23.81, and 24.63. The
MSRI Project would replace three of these PDs (i.e., 23.71, 23.81, and
24.63) which are situated approximately 13.5 km upstream and east of
Astoria, Oregon, along the Federal Navigation Channel. The area
experiences frequent vessel traffic, including recreational boats,
tugboats, and large cargo vessels, which all contribute to the in-air
and underwater acoustic environment.
The CI Project construction area is located between RM 68 and RM 71
of the LCR in Cowlitz County, Washington (figure 2). A total of 10 PDs
would be replaced along Cottonwood Island in the Columbia River at RM
68.35, 68.57, 68.79, 69.01, 69.25, 69.51, 69.79, 70.07, 71.17, and
71.51. The project site is approximately 3.5 km upstream and southeast
of Longview, Washington, directly south of the Cowlitz River confluence
with the Columbia River. The CI Project area is situated within a
highly industrialized area, and experiences frequent recreational and
commercial vessel traffic, which all contribute to the in-air and
underwater acoustic environment.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN27AP26.075
[[Page 22501]]
Figure 1--USACE Miller Sands-Rice Island Dike Repairs Project Site Map
[GRAPHIC] [TIFF OMITTED] TN27AP26.076
Figure 2--USACE Cottonwood Island Dike Repairs Project Site Map
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
The MSRI Project and the CI Project are needed to manage sediments,
direct flow, provide bank protection, reduce the frequency and need of
dredging, and to improve navigability within the LCR Federal Navigation
Channel (FNC). The present-day pile dike system was built from 1917
through 1923 and from 1933 through 1939. After decades of deferred
maintenance and repairs, the LCR pile dike system no longer functions
as initially designed. Therefore, both of these proposed projects would
replace degraded pile dikes and improve vessel navigability within
sections of the FNC in the Columbia River.
The MSRI Project involves five construction activities:
1. Removing debris behind existing pile dikes.
2. Removing degraded timber piles, spreaders, and hardware.
3. Enhancing enrockment at three PDs (23.71, 23.81, and 24.63) by
mechanically placing rock on the prior PD footprint and connecting
enrockment between PD 23.71 and PD 23.81.
4. Installing eight new isolated ATON piles.
5. Site access and staging.
Debris removal and disposal would be followed by mechanical removal
by direct pull methods or breaking existing timber piles at the
mudline; therefore, vibratory pile extraction would not be necessary.
Rock would be transported by barge and placed at each dike location
using a crane or long-arm excavator with a clamshell bucket, orange
peel grapple, or excavator bucket. Rocks (ranging from 50 to 1,000
pounds [22 to 454 kilograms]) would be lowered below the water's
surface and released directly above the existing substrate. Rock
placement would occur during the in-water work window (November-
February), as well as in September and October.
After rock placement, eight new 24-inch steel pipe ATON piles would
be installed to mark each PD and the PD connector. Vibratory hammers
would be used to drive ATON piles to the point of refusal and then an
impact hammer would be used to ensure that the piles are seated in the
substrate. Impact and vibratory pile installation would occur over 8
days and sound produced from these activities has the potential to
result in incidental take of marine mammals by Level A and Level B
harassment. Activities 1, 2, 3, and 5 are not expected to cause take of
marine mammals because these activities do not produce sound with
characteristics likely to result in marine mammal harassment and are
thus not discussed further.
[[Page 22502]]
Table 1--MSRI Project Pile Installation Summary
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Time (minutes)
Method Pile size, Pile type and Piles/day (min- or (strikes/ Number of Min duration Max duration
material location max) pile) piles (days)
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Vibratory....................... 24-inch steel pipe ATON-PD 23.71..... 1-8 12 2 1 2
Impact.......................... (225)
Vibratory....................... 24-inch steel pipe ATON/Enrockment 12 1 1
between PD 23.71
and PD 23.81.
Impact.......................... (225)
Vibratory....................... 24-inch steel pipe ATON/PD 23.81..... 12 2 2
Impact.......................... (225)
Vibratory....................... 24-inch steel pipe ATON/24.63........ 12 3 3
Impact.......................... (225)
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Totals...................... .................. .................. .............. .............. 8 1 8
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The Cottonwood Project involves 5 construction activities:
1. Construction and removal of Material Offload Facilities (MOF).
2. Removal of 162 existing timber piles.
3. Installation of 114 new 12-inch timber piles offset from the
original 5 PDs at RM 68.35, 69.01, 69.51, 69.76, and 70.7.
4. Installation of 17 steel pipe ATON piles between 10.75-24-inches
in diameter.
5. Adding rock around the new piles for scour protection.
All materials associated with the CI Project would initially be
transported by barges and tugboats to the construction site, which
would be anchored in place with spuds. The MOF piles would be installed
with a vibratory hammer and consist of 18 24-inch steel pipe piles and
100 24-inch steel sheet piles. A maximum of three MOFs can be built
over 21 days and then removed over 10.5 days using vibratory methods.
Existing damaged piles would be removed by vertical pull or by breaking
them off at the mudline.
New piles would be installed using a vibratory hammer to the point
of refusal and then an impact hammer would be used to ensure piles are
seated in the substrate. Both timber and steel ATON piles can be
installed on the same day, but only one pile at a time, with a maximum
of 8 piles per day. Pile installation would occur over approximately 34
days.
All project activities, except for PD 68.35, would take place
anytime during the in-water work window from November 2026 to February
2027. Work on PD 68.35 would be restricted to November due to its close
proximity (200 meters (m)) to a seasonal pinniped haulout site.
Activities 1, 3, and 4, which involve pile installation and removal
with vibratory and impact hammers, and sound produced from these
activities has the potential to result in incidental take of marine
mammals by Level A and Level B harassment. Activities 2 and 5 are not
expected to cause take of marine mammals because these activities do
not produce sound with characteristics likely to result in marine
mammal harassment and are thus not discussed further.
Table 2--CI Project Pile Installation and Removal Summary
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Time/pile Expected
Method Pile size, Pile type and/or (minutes), Number of Max piles/day Min duration duration
material location (strikes/pile) piles (days) (days)
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Installation
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Vibratory....................... 10.75-12-inch ATON.............. 12 11 4 2.75 11
steel pipe.
Impact.......................... 4.5 (225)
Vibratory....................... 16-inch steel pipe ATON.............. 12 4 3 1.5 4
Impact.......................... 4.5 (225)
Vibratory....................... 24-inch steel pipe ATON.............. 12 2 1 2 2
Impact.......................... 4.5 (225)
Vibratory....................... 12-inch timber PD 68.35.......... 8 14 8 1.8 2
pole.
Impact.......................... 4.5 (225)
Vibratory....................... 12-inch timber PD 69.01.......... 8 14 8 1.8 2
pole.
Impact.......................... 4.5 (225)
Vibratory....................... 12-inch timber PD 69.51.......... 8 18 8 2.3 3
pole.
Impact.......................... 4.5 (225)
Vibratory....................... 12-inch timber PD 69.76.......... 8 35 8 4.4 5
pole.
Impact.......................... 4.5 (225)
Vibratory....................... 12-inch timber PD 70.7........... 8 33 8 4.1 5
pole.
Impact.......................... 4.5 (225)
Vibratory....................... 24-inch steel pipe MOF 1............. 12 18 8 2.25 3
Vibratory....................... 24-inch steel MOF 1............. 10 100 25 4 4
sheet.
Vibratory....................... 24-inch steel pipe MOF 2............. 12 18 8 2.25 3
Vibratory....................... 24-inch steel MOF 2............. 10 100 25 4 4
sheet.
Vibratory....................... 24-inch steel pipe MOF 3............. 12 18 8 2.25 3
[[Page 22503]]
Vibratory....................... 24-inch steel MOF 3............. 10 100 25 4 4
sheet.
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Total Duration of Pile Installation (days).......................................................................... 39.4 55
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MOF Removal
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Vibratory....................... 24-inch steel pipe MOF 1............. 12 18 8 2.25 3
Vibratory....................... 24-inch steel MOF 1............. 3 100 200 0.5 0.5
sheet.
Vibratory....................... 24-inch steel pipe MOF 2............. 12 18 8 2.25 3
Vibratory....................... 24-inch steel MOF 2............. 3 100 200 0.5 0.5
sheet.
Vibratory....................... 24-inch steel pipe MOF 3............. 12 18 8 2.25 3
Vibratory....................... 24-inch steel MOF 3............. 3 100 200 0.5 0.5
sheet.
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Total Duration of Pile Removal (days)............................................................................... 8.25 10.5
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Total Duration of Pile Driving and Removal (days)................................................................... 47.65 65.5
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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. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 3 lists all four species and stocks for which take is
expected and proposed to be authorized for the MSRI Project and a
subset of three species (California sea lion, Steller sea lion, and
harbor seal) for which take is expected and proposed to be authorized
the CI Project. Tables 3 summarizes information related to the
population or stock, including regulatory status under the MMPA and
Endangered Species Act (ESA) and potential biological removal (PBR),
where known. PBR is defined by the MMPA as the maximum number of
animals, not including natural mortalities, that may be removed from a
marine mammal stock while allowing that stock to reach or maintain its
optimum sustainable population (as described in NMFS' SARs). While no
serious injury or mortality is anticipated or proposed to be authorized
here, PBR and annual serious injury and mortality (M/SI) from
anthropogenic sources are included here as gross indicators of the
status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS' U.S. Alaska and Pacific SARs. All values presented in table 3 are
the most recent available at the time of publication (including from
the draft 2024 SARs) and are available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.
Table 3--Species \1\ With Estimated Take From the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/ MMPA status; Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\2\ abundance survey) \3\ SI \4\
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Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Family Phocoenidae (porpoises):
Harbor Porpoise \5\............. Phocoena phocoena...... Northern OR/WA Coast... -, -, N 22,074 (0.391, 16,068, 161 >=3.2
2022).
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Order Carnivora--Pinnipedia
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Family Otariidae (eared seals and
sea lions):
CA Sea Lion..................... Zalophus californianus. U.S.................... -, -, N 257,606 (N/A, 233,515, 14,011 >321
2014).
Steller Sea Lion................ Eumetopias jubatus..... Eastern................ -, -, N 36,308 (N/A, 36,308, 2,178 93.2
2022) \6\.
Family Phocidae (earless seals):
[[Page 22504]]
Harbor Seal..................... Phoca vitulina......... OR/WA Coastal.......... -, -, N 22,549 (UNK, 19,561, UND \8\ 10.6
2022) \7\.
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\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
(<a href="https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies">https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies</a>)
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region</a>. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, 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.
\5\ Incidental take of harbor porpoises is not expected or proposed for authorization for the CI Project.
\6\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the U.S.
only.
\7\ Most recent SAR does not include an abundance estimate for this stock. These data are for the Washington coast and thus underestimate the size of
the OR/WA Coastal stock; estimates are from Pearson et al. 2024.
\8\ UND means undetermined.
As indicated above, all four species (with four managed stocks) of
marine mammals in table 3 spatially and temporally co-occur to the
degree that take is reasonably likely to occur in the proposed MSRI
Project area. However, California sea lions, Steller sea lions, and
harbor seals could spatially co-occur within the CI Project area to the
degree that take is reasonably likely to occur.
While gray whales, humpback whales, killer whales, and northern
elephant seals have been reported in the LCR, the temporal or spatial
occurrence of these species is such that take is not expected to occur,
and they are not discussed further beyond the explanation provided
here. Gray whales, humpback whales, and killer whales have been
documented in the LCR, but sightings of these animals have primarily
been at RM 11 and below, and sightings above this area are considered
rare (no sightings in recent years) within both project areas. Northern
elephant seals have been documented within the LCR but all reported
sightings of these species within the project areas are over 40 years
old and all recent sightings have occurred below RM 11 in the Columbia
River. Therefore, take of these species is not expected nor proposed to
be authorized and these species are not considered further in this
document.
Harbor Porpoise
In the eastern North Pacific Ocean, harbor porpoises are found in
coastal and inland waters from Point Barrow, along the Alaskan coast,
and down the west coast of North America to Point Conception,
California. Harbor porpoises are known to occur year-round in the
inland trans-boundary waters of Washington and British Columbia, Canada
and along the Oregon/Washington coast.
Harbor porpoise movement along west coast of the United States is
relatively restricted and they do not move extensively between
California, Oregon, and Washington (Calambokidis and Barlow, 1991). The
Northern Oregon/Washington Coast stock of harbor porpoises ranges from
Lincoln City, Oregon, to Cape Flattery, Washington and the stock
commonly occurs in the Columbia River Estuary (Carretta et al., 2020).
Their nearshore abundance peaks with anchovy presence, which is
generally June through October. In 2024, three harbor porpoises were
documented over 33 days of marine mammal monitoring for year 2 of
USACE's East and West Sand Island Pile Dike Repairs Project at RM 4.
Considering the spatial and temporal distribution, harbor porpoises
could occur in the MRSI Project area but are not unexpected to occur in
the CI Project area.
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,
at RM 146. However, the total number of California sea lions observed
at Bonneville Dam has been in decline, ranging from 195 individuals in
2015 to 24 individuals in 2021, and 50 individuals in 2023 (Braun et
al., 2024).
In recent years, California sea lions have been reported below
Bonneville Dam (RM 146) feeding on returning white sturgeon (Acipenser
transmontanus) and adult salmonids (Braun et al., 2024). California sea
lions have been observed hauling out at East Mooring Basin in Astoria,
Oregon, city docks in Rainier, Oregon, and the Cowlitz River mouth in
Longview, Washington (Oregon Department of Fish and Wildlife [ODFW],
2024). Considering the spatial and temporal distribution, California
sea lions are expected to occur in both the MSRI and CI Project areas.
Steller Sea Lion
Steller sea lions that occur in the LCR, including the project
vicinity, are members of the eastern Distinct Population Segment (DPS),
ranging from Southeast Alaska to central California, including both
Oregon and Washington (Jeffries et al., 2000; Scordino, 2006; NMFS,
2013). In Washington, Steller sea lions occur mainly along the outer
coast from the Columbia River to Cape Flattery (Jeffries et al., 2000).
The eastern DPS of Steller sea lions has historically bred on rookeries
located in Southeast Alaska, British Columbia, Oregon, and California.
However, within the last several years, a new rookery has become
established on the outer Washington coast at the Carroll Island and Sea
Lion Rock complex (Muto et al., 2019).
Steller sea lions have also been observed at the base of Bonneville
Dam (RM 146) in recent years, feeding on white sturgeon (Acipenser
transmontanus) and salmonids (Braun et al., 2024). Steller sea lions
have been observed hauling out at the South Jetty at the mouth of the
Columbia River, city docks in Rainier, OR, and the Cowlitz River mouth
in Longview, WA (ODFW, 2024). Considering the spatial and temporal
distribution, Steller sea lions
[[Page 22505]]
are expected to occur in both the MSRI and CI Project areas.
Harbor Seal
Harbor seals are the most common, widely distributed marine mammal
found in Washington and Oregon marine waters and are frequently
observed in the nearshore marine environment. The Oregon/Washington
Coastal Stock was most recently estimated at 22,549 harbor seals in
2024 (Pearson et al., 2024). Harbor seals use hundreds of sites to rest
or haulout along coastal and inland waters, including intertidal sand
bars and mudflats in estuaries; intertidal rocks and reefs; sandy,
cobble, and rocky beaches; islands; and log booms, docks, and floats in
all marine areas of the state (Harvey 1987; Jeffries et al., 2003).
Harbor seals in this population are typically non-migratory and
reside year-round in the Columbia River and generally remain in the
same area throughout the year for breeding and feeding. Pupping seasons
in coastal estuaries vary geographically; in the Columbia River,
Willapa Bay, and Grays Harbor, pups are born from mid-April through
June (Jeffries et al., 2003). Harbor seals in the Columbia River do
exhibit some seasonal movement upriver, including into or through both
of USACE's proposed project areas, to follow winter and spring runs of
Pacific eulachon and outmigrating juvenile salmon (Oncorhynchus spp.),
and they are observed regularly in the Columbia River including the
action areas. Within the lower Columbia River, they tend to congregate
to feed at the mouths of tributary rivers, including the Cowlitz and
Kalama rivers (RMs 68 and 73, respectively). Washington Department of
Fish and Wildlife's (WDFW's) atlas of seal and sea lion haulout sites
(Jeffries et al., 2000) identifies shoals near the confluence of the
Cowlitz and Columbia rivers, one of which is located 200 m from the CI
Project site, as a documented haulout site. Additionally, ODFW has
documented harbor seals hauled out near the MSRI Project area at Taylor
Sands Island, around Green Island, and in Grays Bay during the months
of May through June (Edwards, personal communication, 2023). Therefore,
harbor seals could enter both of USACE's proposed project areas during
in-water construction.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al.
(2007; 2019) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges (behavioral response
data, anatomical modeling, etc.). Generalized hearing ranges were
chosen based on the ~65 decibel (dB) threshold from composite
audiograms, previous analyses in NMFS (2018), and/or data from Southall
et al. (2007, 2019). We note that the names of two hearing groups and
the generalized hearing ranges of all marine mammal hearing groups have
been recently updated (NMFS, 2024) as reflected below in table 4.
Table 4--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 36 kHz.
whales).
High-frequency (HF) cetaceans (dolphins, 150 Hz to 160 kHz.
toothed whales, beaked whales, bottlenose
whales).
Very High-frequency (VHF) cetaceans....... 200 Hz to 165 kHz.
(true porpoises, Kogia, river dolphins,
Cephalorhynchid, Lagenorhynchus cruciger
& L. australis).
Phocid pinnipeds (PW) (underwater) (true 40 Hz to 90 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 68 kHz.
lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges may not be as broad. Generalized hearing range
chosen based on approximately 65 dB threshold from composite
audiogram, previous analysis in NMFS (2018), and/or data from Southall
et al. (2007, 2019). Additionally, animals are able to detect very
loud sounds above and below that ``generalized'' hearing range.
For more details concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section provides a discussion of the ways in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals section later in this document
includes a quantitative analysis of the number of individuals that are
expected to be taken by this activity. The Negligible Impact Analysis
and Determination section considers the content of this section, the
Estimated Take of Marine Mammals section, and the Proposed Mitigation
section, to draw conclusions regarding the likely impacts of these
activities on the reproductive success or survivorship of individuals
and whether those impacts are reasonably expected to, or reasonably
likely to, adversely affect the species or stock through effects on
annual rates of recruitment or survival.
Acoustic effects on marine mammal during the specified activities
for the MSRI Project and CI Project could occur from impact pile
driving and vibratory pile driving and removal. The effects of
underwater noise from USACE's proposed activities have the potential to
result in Level A and Level B harassment of marine mammals in the
proposed action areas.
Description of Sound Sources
The marine soundscape is comprised of both ambient and
anthropogenic sounds. Ambient sound is defined as the all-encompassing
sound in a given place and is usually a composite of sound from many
sources both near and far (American National Standards Institute
(ANSI), 1995). The sound level of an area is defined by the total
acoustical energy being generated by known and unknown sources. These
sources may include physical (e.g., waves, wind, precipitation,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced
by marine mammals, fish, and invertebrates), and anthropogenic sound
(e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor, and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10-20 dB
from day to day (Richardson et al., 1995). The result is
[[Page 22506]]
that, depending on the source type and its intensity, sound from the
specified activities may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
In-water construction associated with the proposed projects would
include impact and vibratory pile driving and removal. The sounds
produced by these activities fall into one of two general sound types:
impulsive and non-impulsive. Impulsive sounds (e.g., explosions,
gunshots, sonic booms, impact pile driving) are typically transient,
brief (less than 1 second), broadband, and consist of high peak sound
pressure with rapid rise time and rapid decay (ANSI, 1986; National
Institute for Occupational Safety and Health (NIOSH), 1998; ANSI, 2005;
NMFS, 2018). Non-impulsive sounds (e.g., aircraft, machinery operations
such as drilling or dredging, vibratory pile driving, and active sonar
systems) can be broadband, narrowband or tonal, brief or prolonged
(continuous or intermittent), and typically do not have the high peak
sound pressure with rapid rise/decay time that impulsive sounds do
(ANSI, 1995; NIOSH, 1998; NMFS, 2018). The distinction between these
two sound types is important because they have differing potential to
cause physical effects, particularly with regard to hearing (e.g., Ward
1997 in Southall et al., 2007).
Both impact and vibratory pile hammers would be used on the MSRI
and CI Projects. Impact hammers operate by repeatedly dropping a heavy
piston onto a pile to drive the pile into the substrate. Sound
generated by impact hammers is characterized by rapid rise times and
high peak levels, a potentially injurious combination (Hastings and
Popper, 2005). Vibratory hammers install piles by vibrating them and
allowing the weight of the hammer to push them into the sediment.
Vibratory hammers produce significantly less sound than impact hammers.
Peak sound pressure levels (SPLs) may be 180 dB or greater but are
generally 10 to 20 dB lower than SPLs generated during impact pile
driving of the same-sized pile (Oestman et al., 2009). Rise time is
slower, reducing the probability and severity of injury, and sound
energy is distributed over a greater amount of time (Nedwell and
Edwards, 2002; Carlson et al., 2005).
The likely or possible impacts of the USACE's proposed activities
on marine mammals could involve both non-acoustic and acoustic
stressors. Potential non-acoustic stressors could result from the
physical presence of the equipment, vessel, and personnel; however, we
expect that any animals that approach the project sites close enough to
be harassed due to the presence of equipment or personnel would be
within the Level B harassment zones from pile driving would already be
subject to harassment from the in-water activities. Therefore, any
impacts to marine mammals are expected to primarily be acoustic in
nature. Acoustic stressors would be generated by heavy equipment
operation during pile installation and removal (i.e., impact and
vibratory pile driving and removal).
Potential Effects of Underwater Sound on Marine Mammals
The introduction of anthropogenic noise into the aquatic
environment from impact and vibratory pile driving and removal is the
primary means by which marine mammals may be harassed from the USACE's
specified activities. 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. Broadly, underwater
sound from active acoustic sources, such as those in the Projects, 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., 2003; Nowacek et al., 2007; Southall et al.,
2007; G[ouml]tz et al., 2009).
We describe the more severe effects of certain non-auditory
physical or physiological effects only briefly as we do not expect that
use of pile driving hammers (impact and vibratory) is reasonably likely
to result in such effects (see below for further discussion). Potential
effects from impulsive sound sources can range in severity from effects
such as behavioral disturbance or tactile perception to physical
discomfort, slight injury of the internal organs and the auditory
system, or mortality (Yelverton et al., 1973). 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; Tal et al., 2015). Each project's
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.
In general, animals exposed to natural or anthropogenic sound may
experience physical and psychological effects, ranging in magnitude
from none to severe (Southall et al., 2007, 2019). Exposure to
anthropogenic noise has the potential to result in auditory threshold
shifts and behavioral reactions (e.g., avoidance, temporary cessation
of foraging and vocalizing, changes in dive behavior). It can also lead
to non-observable physiological responses, such an increase in stress
hormones. Additional noise in a marine mammal's habitat can mask
acoustic cues used by marine mammals to carry out daily functions, such
as communication and predator and prey detection.
The degree of effect of an acoustic exposure on marine mammals is
dependent on several factors, including, but not limited to, sound type
(e.g., impulsive vs. non-impulsive), signal characteristics, the
species, age and sex class (e.g., adult male vs. mom with calf),
duration of exposure, the distance between the noise source and the
animal, received levels, behavioral state at time of exposure, and
previous history with exposure (Wartzok et al., 2004; Southall et al.,
2007). In general, sudden, high-intensity sounds can cause hearing loss
as can longer exposures to lower-intensity sounds. Moreover, any
temporary or permanent loss of hearing, if it occurs at all, will occur
almost exclusively for noise within an animal's hearing range. We
describe below the specific manifestations of acoustic effects that may
occur based on each of the activities proposed by the USACE.
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 (at the greatest distance) 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 (closer to the receiving animal) corresponds
with the area where the signal is audible to the animal and of
sufficient intensity to elicit behavioral or physiological
responsiveness. The 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
[[Page 22507]]
(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 masking zone may be highly variable in size.
Below, we provide additional details regarding potential impacts on
marine mammals and their habitat from noise in general, starting with
hearing impairment, as well as from the specific activities the USACE
plans to conduct, to the degree it is available.
Auditory Injury (AUD INJ)--NMFS defines auditory injury as ``damage
to the inner ear that can result in destruction of tissue . . . which
may or may not result in permanent threshold shifts (PTS)'' (NMFS,
2024). NMFS defines PTS as a permanent, irreversible increase in the
threshold of audibility at a specified frequency or portion of an
individual's hearing range above a previously established reference
level (NMFS, 2024). PTS does not generally affect more than a limited
frequency range, and an animal that has incurred PTS has incurred some
level of hearing loss at the relevant frequencies; typically, animals
with PTS are not functionally deaf (Au and Hastings, 2008; Finneran,
2016). Available data from humans and other terrestrial mammals
indicate that a 40-dB threshold shift approximates PTS onset (see Ward
et al., 1958, 1959, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et
al., 1996; Henderson et al., 2008). PTS levels for marine mammals are
estimates, as with the exception of a single study unintentionally
inducing PTS in a harbor seal (Kastak et al., 2008), there are no
empirical data measuring PTS in marine mammals largely due to the fact
that, for various ethical reasons, experiments involving anthropogenic
noise exposure at levels inducing PTS are not typically pursued or
authorized (NMFS, 2018).
Temporary Threshold Shift (TTS)--TTS is a temporary, reversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established
reference level (NMFS, 2018). Based on data from cetacean TTS
measurements (Southall et al., 2007, 2019), a TTS of 6 dB is considered
the minimum Threshold Shift (TS) clearly larger than any day-to-day or
session-to-session variation in a subject's normal hearing ability
(Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in
Finneran (2015), marine mammal studies have shown the amount of TTS
increases with cumulative sound exposure level (SELcum) in an
accelerating fashion: At low exposures with lower SELcum, the amount of
TTS is typically small and the growth curves have shallow slopes. At
exposures with higher SELcum, the growth curves become steeper and
approach linear relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration
(i.e., recovery time), and frequency range of TTS, and the context in
which it is experienced, TTS can have effects on marine mammals ranging
from discountable to serious (similar to those discussed in auditory
masking, below). For example, a marine mammal may be able to readily
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal
is traveling through the open ocean, where ambient noise is lower and
there are not as many competing sounds present. Alternatively, a larger
amount and longer duration of TTS sustained during a time when
communication is critical for successful mother/calf interactions could
have more serious impacts. We note that reduced hearing sensitivity as
a simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al., 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without cost.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. For
pinnipeds in water, measurements of TTS are limited to harbor seals,
elephant seals (Mirounga angustirostris), bearded seals (Erignathus
barbatus) and California sea lions (Kastak et al., 1999, 2007;
Kastelein et al., 2019b, 2019c, 2021, 2022a, 2022b; Reichmuth et al.,
2019; Sills et al., 2020). These studies examined hearing thresholds
measured in marine mammals before and after exposure to intense or
long-duration sound exposures. The difference between the pre-exposure
and post-exposure thresholds can be used to determine the amount of TS
at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity
for a species or hearing group, are less hazardous than those at higher
frequencies, near the region of best sensitivity (Finneran and
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are
higher compared to those in the region of best sensitivity (i.e., a low
frequency noise would need to be louder to cause TTS onset when TTS
exposure level is higher), as shown for harbor porpoises and harbor
seals (Kastelein et al., 2019a, 2019c). Note that in general, harbor
seals have a lower TTS onset than other measured pinniped species
(Finneran, 2015). In addition, TTS can accumulate across multiple
exposures, but the resulting TTS will be less than the TTS from a
single, continuous exposure with the same SEL (Mooney et al., 2009;
Finneran et al., 2010; Kastelein et al., 2014, 2015). This means that
TTS predictions based on the total, SELcum will overestimate the amount
of TTS from intermittent exposures, such as sonars and impulsive
sources. Nachtigall et al. (2018) describes measurements of hearing
sensitivity of multiple odontocete species (i.e., bottlenose dolphin,
harbor porpoise, beluga, and false killer whale (Pseudorca crassidens))
when a relatively loud sound was preceded by a warning sound. These
captive animals were shown to reduce hearing sensitivity when warned of
an impending intense sound. Based on these experimental observations of
captive animals, the authors suggest that wild animals may dampen their
hearing during prolonged exposures or if conditioned to anticipate
intense sounds. Another study showed that echolocating animals
(including odontocetes) might have anatomical specializations that
might allow for conditioned hearing reduction and filtering of low-
frequency ambient noise, including increased stiffness and control of
middle ear structures and placement of inner ear structures (Ketten et
al., 2021). Additionally, the existing marine mammal TTS data come from
a limited number of individuals within these species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, 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 dBs above that inducing mild TTS
(e.g., a 40-dB TS approximates PTS onset (Kryter et al., 1966; Miller,
1974), while a 6-dB TS approximates TTS onset (Southall et al., 2007,
2019). Based on
[[Page 22508]]
data from terrestrial mammals, a precautionary assumption is that the
PTS thresholds for impulsive sounds (such as impact pile driving pulses
as received close to the source) are at least 6 dB higher than the TTS
threshold on a peak-pressure basis and PTS SELcum thresholds are 15 to
20 dB higher than TTS SELcum thresholds (Southall et al., 2007, 2019).
Given the higher level of sound or longer exposure duration necessary
to cause PTS as compared with TTS, it is considerably less likely that
PTS could occur.
Pile dike repairs for the MSRI and CI Projects would require impact
pile driving and vibratory pile driving and removal. Construction
activities for each project would occur independently under separate
authorizations. For each project, only one method of pile installation
or removal would occur at a time, although multiple pile driving
methods may be used on the same day. Pile driving associated with each
project is not expected to be constant and pauses in the activities
producing sounds are likely. Given these pauses and that many marine
mammals would be transiting through the project areas and not remaining
for extended periods of time, the potential for TS declines. For
California sea lions, Steller sea lions, and harbor seals, animals are
expected to remain in the CI project area, particularly around haulout
site 24, which is a sand bar where the Cowlitz River and Carrols
Channel meet with the mainstem Columbia River. California sea lions and
Steller sea lions could also remain near the CI Project area as they
transit to and from haulout site 24, and other structures near the
Rainier, Oregon waterfront. Animals swimming with heads underwater
would be exposed to pile driving noise throughout a day on multiple
days, increasing risk of TS. However, we also expect these individuals
to remain out of the water on haulouts for extended durations which
reduces risk of TS.
Behavioral Harassment--Exposure to noise from pile driving and
removal also have the potential to behaviorally disturb marine mammals.
Available studies show wide variation in response to underwater sound;
therefore, it is difficult to predict specifically how any given sound
in a particular instance might affect marine mammals perceiving the
signal. If a marine mammal does react briefly to an underwater sound by
changing its behavior or moving a small distance, the impacts of the
change are unlikely to be significant to the individual, let alone the
stock or population. However, if a sound source displaces marine
mammals from an important feeding or breeding area for a prolonged
period, impacts on individuals and populations could be significant
(e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 2005).
Disturbance may result in changing durations of surfacing and
dives, number of blows per surfacing, or moving direction and/or speed;
reduced/increased vocal activities; changing/cessation of certain
behavioral activities (such as socializing or feeding); visible startle
response or aggressive behavior (such as tail/fluke slapping or jaw
clapping); avoidance of areas where sound sources are located.
Pinnipeds may increase their haul out time, possibly to avoid in-water
disturbance (Thorson and Reyff, 2006). Behavioral responses to sound
are highly variable and context-specific and any reactions depend on
numerous intrinsic and extrinsic factors (e.g., species, state of
maturity, experience, current activity, reproductive state, auditory
sensitivity, time of day), as well as the interplay between factors
(e.g., Richardson et al., 1995; Wartzok et al., 2004; Southall et al.,
2007, 2021; Weilgart, 2007; Archer et al., 2010). Behavioral reactions
can vary not only among individuals but also within exposures of an
individual, depending on previous experience with a sound source,
context, and numerous other factors (Ellison et al., 2012, Southall et
al., 2021), and can vary depending on characteristics associated with
the sound source (e.g., whether it is moving or stationary, number of
sources, distance from the source). In general, pinnipeds seem more
tolerant of, or at least habituate more quickly too, potentially
disturbing underwater sound than do cetaceans, and generally seem to be
less responsive to exposure to industrial sound than most cetaceans.
For a review of the studies involving marine mammal behavioral
responses to sound, see Southall et al., 2007; Gomez et al., 2016; and
Southall et al., 2021 reviews.
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 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.
Airborne Acoustic Effects--Pinnipeds that occur near the project
sites could be exposed to airborne sounds associated with pile driving
and removal that have the potential to cause behavioral harassment,
depending on their distance from the activities. Cetaceans are not
expected to be exposed to airborne sounds that would result in
harassment as defined under the MMPA.
Airborne noise would primarily be an issue for pinnipeds that are
swimming or hauled out near the project sites within the range of noise
levels elevated above the airborne acoustic harassment criteria. We
recognize that pinnipeds in the water could be exposed to airborne
sound that may result in behavioral harassment when swimming with their
heads above water. Most likely, airborne sounds 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.
Stress Response--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
[[Page 22509]]
significant long-term effect on an animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses glycogen stores
that can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker, 2000;
Romano et al., 2002b) and, more rarely, studied in wild populations
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found
that noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals will experience physiological stress responses upon exposure to
acoustic stressors and that it is possible that some of these would be
classified as ``distress.'' In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2005), however
distress is an unlikely result of these projects based on observations
of marine mammals during previous, similar construction projects in the
LCR.
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, pile driving) 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.
Masking of natural sounds can result when human activities produce high
levels of background sound at frequencies important to marine mammals.
Conversely, if the background level of underwater sound is high (e.g.,
on a day with strong wind and high waves), an anthropogenic sound
source would not be detectable as far away as would be possible under
quieter conditions and would itself be masked.
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; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or 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 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.
The MSRI and CI Projects are located in areas with routine vessel
traffic from recreational and commercial vessels; therefore, background
sound levels are generally already elevated.
Marine Mammal Habitat Effects
Proposed construction for the MSRI and CI Projects could have
localized, temporary impacts on marine mammal habitat, including prey,
by increasing in-water SPLs and slightly decreasing water quality.
Increased noise levels may affect acoustic habitat (see Auditory
Masking) and adversely affect marine mammal prey in the vicinity of the
project area (see discussion below). During impact and vibratory pile
driving or removal, elevated levels of underwater noise would ensonify
the project areas where both fish and mammals occur and could affect
foraging success. Additionally, marine
[[Page 22510]]
mammals may avoid the areas during construction; however, displacement
due to noise is expected to be temporary and is not expected to result
in long-term effects to the individuals or populations. Each project
would be relatively short in duration and would likely only have
temporary impacts on marine mammal habitat through increases in
underwater and airborne sound.
Water Quality--In-water pile driving activities would also cause
short-term effects on water quality due to increased turbidity.
Temporary and localized increase in turbidity near the riverbed would
occur in the immediate area surrounding where piles are installed or
removed and where rock placement occurs due benthic sediment
disturbance. In general, turbidity associated with pile installation is
localized to about a 25 ft (7.6 m) radius around the pile (Everitt et
al., 1980). The sediments of the project sites would settle out of the
water column rapidly when disturbed. Local currents and tides are
anticipated to disburse any additional suspended sediments produced by
each of the project's activities at moderate to rapid rates depending
on river current or tidal stage. Studies of the effects of turbid water
on fish (marine mammal prey) suggest that concentrations of suspended
sediment can reach thousands of milligrams per liter before an acute
toxic reaction is expected (Burton, 1993).
Effects from turbidity and sedimentation are expected to be short-
term, minor, and localized. Suspended solids in the water column should
dissipate and quickly return to background levels in all construction
scenarios. Turbidity within the water column has the potential to
reduce the level of oxygen in the water and irritate the gills of prey
fish species in each of the proposed project's areas. However,
suspended sediment associated with the project would be temporary and
localized, and fish in the proposed project area would be able to move
away from and avoid the areas where plumes may occur. Therefore, it is
expected that the impacts on prey fish species from turbidity, and
therefore on marine mammals, would be minimal and temporary. In
general, the areas likely impacted by the proposed construction
activities are relatively small compared to the total available marine
mammal habitat in the LCR in Oregon and Washington. Therefore, we
expect the impact from increased turbidity levels to be discountable to
marine mammals and do not discuss it further.
In-water Effects on Potential Foraging Habitat--The proposed
activities would not result in permanent impacts to habitats used
directly by marine mammals and only negligible increases in vessel
traffic are expected in either location as a result of the specified
activities. The areas likely impacted by the proposed actions are
relatively small compared to the total available habitat in the LCR in
Oregon and Washington. Each of the proposed project areas are highly
influenced by anthropogenic activities and provide limited foraging
habitat for marine mammals. The total riverbed area affected by pile
driving and rock placement activities is small compared to the vast
foraging areas available to marine mammals both upstream and downstream
the construction sites in the LCR. At best, the area impacted provide
marginal foraging habitat for marine mammals and fishes. Furthermore,
pile driving, pile removal and rock placement would not obstruct
movements or migration of marine mammals.
Construction activities would produce continuous, non-impulsive
(i.e., vibratory pile driving and removal) and intermittent impulsive
(i.e., impact pile driving) sounds. Fish utilize the soundscape and
components of sound in their environment to perform important functions
such as foraging, predator avoidance, mating, and spawning (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 (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Additional studies
have documented effects of pile driving on fish, several of which are
based on studies in support of large, multi-year bridge construction
projects (e.g., Scholik and Yan, 2001; Popper and Hastings, 2009). Many
studies have demonstrated that impulse sounds might affect the
distribution and behavior of some fishes, potentially impacting
foraging opportunities or increasing energetic costs (e.g., Pearson et
al., 1992; Skalski et al., 1992; Santulli et al., 1999; Fewtrell and
McCauley, 2012; Paxton et al., 2017). In response to pile driving,
Pacific sardines (Sardinops sagax) and northern anchovies (Engraulis
mordax) may exhibit an immediate startle response to individual strikes
but return to ``normal'' pre-strike behavior following the conclusion
of pile driving with no evidence of injury as a result (see NAVFAC,
2014). However, some studies have shown no or slight reaction to
impulse sounds (e.g., Wardle et al., 2001; Popper et al., 2005;
Jorgenson and Gyselman, 2009; Pe[ntilde]a et al., 2013).
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 is likely
restored when damaged cells are replaced with new cells. Halvorsen et
al. (2012b) showed that a TTS of 4-6 dB was recoverable within 24 hours
for one species. Impacts would be most severe when the individual fish
is close to the source and when the duration of exposure is long.
Injury caused by barotrauma can range from slight to severe and can
cause death and is most likely for fish with swim bladders. Barotrauma
injuries have been documented during controlled exposure to impact pile
driving (Halvorsen et al., 2012a; Casper et al., 2013) and the greatest
potential effect on fish during the proposed project would occur during
impact pile driving. Impact pile driving for each of the proposed USACE
construction projects would constitute a small proportion of total in-
water construction time. For the MSRI Project, impact driving would be
limited to 6 minutes per pile; consequently, installing all eight piles
in a single day would result in a maximum of 48 minutes of impact
noise. Similarly, the CI Project would require only 4.5 minutes of
impact driving per pile, resulting in a total daily duration of just 36
minutes if eight piles are installed. In-water construction would be
restricted to daylight hours (defined as 30 minutes before sunrise to
30 minutes after sunset) which would allow fish to forage and transit
the area undisturbed
[[Page 22511]]
at night. While vibratory pile driving may elicit temporary behavioral
avoidance, it is unlikely to cause injury or have persistent effects on
local populations. Furthermore, all installation would occur within
USACE and USFWS-designated work windows from November 1, 2026, through
February 28, 2027, to minimize exposure for migrating ESA-listed fish
species. Notably, the MSRI and CI Project areas already experience
significant anthropogenic noise from regular vessel traffic, with the
CI Project area subject to additional noise from industrial activities.
The most likely impact to fishes from impact and vibratory pile
driving and removal in project areas would be temporary behavioral
avoidance of the area. The duration of fish avoidance of the area after
pile driving stops is unknown but a rapid return to normal recruitment,
distribution, and behavior is anticipated. There are times of known
seasonal marine mammal foraging when fish are aggregating but the
impacted areas are small portions of the total foraging habitats
available in the LCR. In general, impacts to marine mammal prey species
are expected to be minor and temporary. Further, it is anticipated that
preparation activities for pile driving (i.e., positioning of the pile
or hammer) and upon initial startup of devices would cause fish to move
away from the affected area where injuries may occur. Therefore,
relatively small portions of the proposed project area would be
affected for short periods of time, and the potential for effects on
fish to occur would be temporary and limited to the duration of
sound[hyphen]generating activities.
Construction activities, in the form of increased turbidity, also
have the potential to adversely affect forage fish in the project area.
As discussed earlier, increased turbidity is expected to occur in the
immediate vicinity (approximately 25 ft (7.6 m) or less) of
construction activities (Everitt et al., 1980). However, suspended
solids are expected to dissipate quickly within a single tidal cycle.
Given the limited area affected and high tidal dilution rates, any
effects on forage fish are expected to be minor or negligible. In
addition, best management practices would be in effect to limit the
extent of turbidity to the immediate project areas. Finally, turbidity
levels resulting from construction activities are expected to remain
within the range of baseline conditions. Fish and marine mammals in
these regions are frequently exposed to significant suspended sediment
loads from winter storm runoff, as well as other natural and
anthropogenic sources.
In summary, given the short daily duration of sound associated with
pile driving and removal the relatively small areas being affected,
pile driving and removal activities associated with the proposed
projects are not likely to have a permanent adverse effect on any fish
habitat, or populations of fish species. Thus, we conclude that impacts
of the specified activity are not likely to have more than short-term
adverse effects on any prey habitat or populations of prey species.
Further, any impacts to marine mammal habitat are not expected to
result in significant or long-term consequences for individual marine
mammals, or to contribute to adverse impacts on their populations.
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
proposed for authorization through the IHAs, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
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 primarily be by Level B harassment (in the
form of behavioral disturbance and temporary threshold shift (TTS)), as
use of the acoustic sources (i.e., vibratory, and impact pile driving;
and vibratory pile removal) has the potential to result in disruption
of behavioral patterns for individual marine mammals. There is also
some potential for auditory injury (Level A harassment), primarily
affecting harbor seals, Steller sea lions, and California sea lions
because of their prevalence in project areas, nearby haulouts, and
predicted AUD INJ zones are relatively larger than for other hearing
groups. The proposed mitigation and monitoring measures are expected to
minimize the severity of the taking to the extent practicable.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic criteria above which NMFS believes there is
some reasonable potential for marine mammals to be behaviorally
harassed or incur some degree of hearing impairment; (2) the area or
volume of water that would be ensonified above these levels in a day;
(3) the density or occurrence of marine mammals within these ensonified
areas; and, (4) the number of days of activities. We note that while
these factors can contribute to a basic calculation to provide an
initial prediction of potential takes, additional information that can
qualitatively inform take estimates is also sometimes available (e.g.,
previous monitoring results or average group size). Below, we describe
the factors considered here in more detail and present the proposed
take estimates.
Acoustic Criteria
NMFS recommends the use of acoustic criteria 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 AUD INJ of some degree (equated to
Level A harassment). Criteria for AUD INJ, and hearing group categories
are available in NMFS' Updated Technical Guidance (NMFS 2024) and are
reflected below in the Level A harassment section.
Level B Harassment--Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007; Southall et al., 2021; Ellison et
al., 2012). Based on what the available science indicates and the
practical need to use a threshold based on a metric that is both
predictable and measurable for most activities, NMFS typically uses a
generalized acoustic threshold based on received level to estimate the
onset of behavioral harassment. NMFS generally predicts that marine
mammals are likely to be behaviorally harassed in a manner considered
to be Level B harassment when exposed to underwater
[[Page 22512]]
anthropogenic noise above root-mean-squared pressure received levels
(RMS SPL) of 120 dB (referenced to 1 micropascal (re 1 [mu]Pa)) for
continuous (e.g., vibratory pile driving, drilling) and above RMS SPL
160 dB re 1 [mu]Pa for non-explosive impulsive (e.g., seismic airguns)
or intermittent (e.g., scientific sonar) sources. Generally speaking,
Level B harassment take estimates based on these behavioral harassment
thresholds are expected to include any likely takes by TTS as, in most
cases, the likelihood of TTS occurs at distances from the source less
than those at which behavioral harassment is likely. TTS of a
sufficient degree can manifest as behavioral harassment, as reduced
hearing sensitivity and the potential reduced opportunities to detect
important signals (conspecific communication, predators, prey) may
result in changes in behavior patterns that would not otherwise occur.
The USACE's proposed activities include the use of continuous
(vibratory hammer) and impulsive (impact hammer) sources, and therefore
the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are applicable.
Level A harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater 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 USACEs' proposed activities include the use of impulsive (impact
hammer) and non-impulsive (vibratory hammer) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in table 5 below. The references, analysis, and
methodology used in the development of the criteria are described in
NMFS' 2024 Updated Technical Guidance, which may be accessed at:
<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>.
Table 5--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
AUD INJ onset acoustic thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 222 dB; Cell 2: LE, LF,24h: 197 dB.
LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: Lpk,flat: 230 dB; Cell 4: LE, HF,24h: 201 dB.
LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,VHF,24h: 181 dB.
LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 223 dB; Cell 8: LE,PW,24h: 195 dB.
LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 230 dB; Cell 10: LE,OW,24h: 199 dB.
LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [mu]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [mu]Pa\2\s. In this table, criteria are abbreviated to be
more reflective of International Organization for Standardization standards (ISO, 2017). The subscript
``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within the
generalized hearing range of marine mammals underwater (i.e., 7 hertz (Hz) to 165 kHz). The subscript
associated with cumulative sound exposure level criteria indicates the designated marine mammal auditory
weighting function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation
period is 24 hours. The weighted cumulative sound exposure level criteria 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 criteria will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss
coefficient.
In order to calculate distances to the Level A and Level B
harassment thresholds for the methods and piles being used in these
projects, NMFS used proxy source levels for the piles that were
identified from the literature. Vibratory and impact pile driving of
steel pipe, timber, and steel sheet piles for the MSRI and CI Projects
were based on the summary of data for each pile material and type
provided by Caltrans (2020, 2015). Table 6 shows the source levels used
for calculating harassment zones for impact driving as well as
vibratory pile driving and removal for the MSRI and CI Projects. The
source levels used were the most suitable due to similar pile sizes,
pile driving, and pile removal methods.
Table 6--Estimated Unattenuated Underwater Sound Pressure Level Associated With Vibratory and Impact Pile Driving for the CI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
SPLs or SEL at 10 meters distance
Source for proxy values -----------------------------------------------------------
Pile type Method used Average Peak SPL, Average RMS SPL, Average SEL, dB re
dB re 1 [mu]Pa dB re 1 [mu]Pa 1 [mu]Pa2-sec
--------------------------------------------------------------------------------------------------------------------------------------------------------
MSRI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch Steel pipe.................... Vibratory Installation... Caltrans (2020).......... 194 157 NA
24-inch Steel pipe.................... Impact installation...... Caltrans (2015).......... 203 190 177
--------------------------------------------------------------------------------------------------------------------------------------------------------
CI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
10-12-inch Steel pipe................. Vibratory Installation... Caltrans (2015).......... 171 155 NA
[[Page 22513]]
10-12-inch steel pipe................. Impact Installation...... Caltrans (2015, 2020).... 192 177 167
16-inch Steel pipe.................... Vibratory Installation... Caltrans (2020).......... 196 158 NA
16-inch Steel pipe.................... Impact Installation...... Caltrans (2020).......... 200 185 175
20-24-inch Steel pipe................. Impact Installation...... Caltrans (2015).......... 203 190 177
24-inch Steel pipe.................... Vibratory Installation... Caltrans (2020).......... 194 157 NA
24-inch AZ Steel sheet................ Vibratory Installation Caltrans (2020).......... 175 160 NA
and Removal.
12-16-inch Timber..................... Vibratory Installation... Caltrans (2020).......... NA 162 NA
12-14-inch Timber..................... Impact installation...... Caltrans (2020).......... 180 170 160
--------------------------------------------------------------------------------------------------------------------------------------------------------
SPL = Sound Pressure Levels; SEL = Sound Exposure Level; RMS = root mean square; dB re 1 [mu]Pa = decibels referenced to 1 micropascal; dB re 1 [mu]Pa2
sec = decibels referenced to 1 micropascal squared second; NA = not applicable. All SPLs and SELs are unattenuated.
Level B Harassment Zones
Transmission loss (TL) is the decrease in acoustic intensity as an
acoustic pressure wave propagates out from a source until the source
becomes indistinguishable from ambient sound. TL parameters vary with
frequency, temperature, river conditions, current, source and receiver
depth, water depth, water chemistry, and bottom composition and
topography. The general formula for underwater TL is:
TL = B * Log10 (R1/R2)
Where:
TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement
The recommended TL coefficient for most nearshore environments is
the practical spreading value of 15. This value results in an expected
propagation environment that would lie between spherical and
cylindrical spreading loss conditions, which is the most appropriate
assumption for the USACE's proposed activities in the absence of
specific modeling. The spreadsheet inputs for pile size, type, and
installation method for each project are included in tables 7 and 8.
The estimated Level B harassment zones for USACE's proposed activities
are shown in tables 9 and 10 for the MSRI and CI Projects,
respectively.
Level A harassment Zones
The ensonified area associated with Level A harassment is more
technically challenging to predict due to the need to account for a
duration component. Therefore, NMFS developed an optional User
Spreadsheet tool to accompany the 2024 Updated Technical Guidance that
can be used to relatively simply predict an isopleth distance for use
in conjunction with marine mammal density or occurrence to help predict
potential takes. We note that because of some of the assumptions
included in the methods underlying this optional tool, we anticipate
that the resulting isopleth estimates are typically going to be
overestimates of some degree, which may result in an overestimate of
potential take by Level A harassment. However, this optional tool
offers the best way to estimate isopleth distances when more
sophisticated modeling methods are not available or practical. For
stationary sources such as impact and vibratory driving, the optional
User Spreadsheet tool predicts the distance at which, if a marine
mammal remained at that distance for the duration of the activity, it
would be expected to incur AUD INJ. Inputs used in the optional User
Spreadsheet tool, and the resulting estimated isopleths, are reported
below.
Table 7--NMFS User Spreadsheet Inputs for the MSRI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distance of
Weighting Transmission Activity sound pressure
Pile size and material Spreadsheet tab Source level (SPL) factor loss duration Number of level
used adjustment coefficient (minutes), or piles per day measurement
(strikes/pile) (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel................... A.1) Vibratory 157 dB RMS........ 2.5 15 12 8 10
Pile Driving.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact pile driving \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel................... E.1) Impact Pile 190 dB RMS, 177 dB 2 15 (225) 8 10
Driving. SEL, 203 dB PK.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ 5 dB of attenuation was applied to impact driving to account for noise reduction from bubble curtains.
[[Page 22514]]
Table 8--NMFS User Spreadsheet Inputs for the CI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distance of
Weighting Transmission Activity sound pressure
Pile size and material Spreadsheet tab Source level (SPL) factor loss duration Number of level
used adjustment coefficient (minutes) or piles per day measurement
(strikes/pile) (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
10.75-12-inch steel pipe........ A.1) Vibratory 155 dB RMS........ 2.5 15 12 4 10
Pile Driving.
16-inch steel pipe.............. 158 dB RMS........ 2.5 15 18 3 10
24-inch steel pipe (ATON)....... 157 dB RMS........ 2.5 15 12 1 10
12-inch timber pole............. 162 dB RMS........ 2.5 15 8 8 10
24-inch steel pipe (MOF)........ 157 dB RMS........ 2.5 15 12 8 10
24-inch Steel Sheet (MOF)....... 160 dB RMS........ 2.5 15 10 25 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel pipe (MOF)........ A.1) Vibratory 157 dB RMS........ 2.5 15 12 8 10
Pile Driving.
24-inch Steel Sheet (MOF)....... 160 dB RMS........ 2,5 15 3 200 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile driving \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
10.75-12-inch steel pipe........ E.1) Impact Pile 177 dB RMS, 167 dB 2 15 (225) 4 10
Driving. SEL, 200 dB PK.
16-inch steel pipe.............. 185 dB RMS, 175 dB 2 15 (225) 3 10
SEL, 200 dB PK.
24-inch steel pipe (ATON)....... 190 dB RMS, 177 dB 2 15 (225) 8 10
SEL, 203 dB PK.
12-inch timber pole............. 170 dB RMS, 160 dB 2 15 (225) 8 10
SEL, 180 dB PK.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ 5 dB of attenuation was applied to impact driving to account for noise reduction from bubble curtains.
Table 9--Projected Distances to Level A Harassment and Level B Harassment Isopleths (m) by Marine Mammal Hearing Groups for Vibratory and Impact
Installation of Piles for the MSRI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment distance (m) Level B
Pile size and material -------------------------------------------------------------------------------- harassment
LF cetaceans HF cetaceans VHF cetaceans PW OW distance (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel pipe...................................... 7 3 6 9 3 2,929
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact pile driving \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel pipe...................................... 272 34 421 242 90 464
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ 5 dB of attenuation was applied to impact driving to account for noise reduction from bubble curtains.
[[Page 22515]]
Table 10--Projected Distances to Level A Harassment and Level B Harassment Isopleths (m) by Marine Mammal Hearing Groups for the Vibratory Installation
or Removal and Impact Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment distance (m) Level B
Pile size and material -------------------------------------------------------------------------------- harassment
LF cetaceans HF cetaceans VHF cetaceans PW OW distance (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
10.75-12-inch steel pipe................................ 3 1 3 4 2 2,154
16-inch steel pipe...................................... 4 2 3 5 2 3,415
24-inch steel pipe (ATON)............................... 2 1 1 2 1 2,929
12-inch timber.......................................... 15 6 12 19 6 6,310
24-inch steel pipe (MOF) \a\............................ 7 3 6 9 3 2,929
24-inch Steel Sheet (MOF) \a\........................... 21 8 19 17 26 4,642
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact pile driving \b\
--------------------------------------------------------------------------------------------------------------------------------------------------------
10.75-12-inch steel pipe................................ 37 5 57 33 12 63
16-inch steel pipe...................................... 104 13 161 93 35 215
24-inch steel pipe (ATON)............................... 68 9 105 60 23 464
12-inch timber.......................................... 20 3 31 18 7 22
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ indicates piles would be installed and removed.
\b\ 5 dB of attenuation was applied to impact driving to account for noise reduction from bubble curtains.
Marine Mammal Occurrence
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations.
For all species, the best available scientific data was considered
to estimate occurrence for both proposed projects.
For the MSRI Project, incidental take is expected to occur for
harbor seals, California lions, Steller sea lions and harbor porpoises.
Occurrence of harbor porpoises for the MSRI Project was derived from a
monitoring report for the USACE Sand Island Pile Dike Replacement
Project, located at RM 4 in the LCR. During the 15 days of monitoring
for that project, seven individual harbor porpoises were observed
(Hammer Environmental L.P., 2020). Based on these observations, USACE
estimates that two harbor porpoises may enter Level B Harassment zones
during the 8 days of pile driving for the MRSI Project. NMFS concurs
with this approach because although harbor porpoises are generally
uncommon in project area, they could potentially occur.
Initially, USACE estimated harbor seal take based on densities
derived from ODFW and WDFW surveys as well as personal communication
with state biologists. Upon review, NMFS determined that the ODFW data
for harbor seals and California sea lions were either outside of the
proposed project area or represented months of peak abundance for these
species which do not align with the MSRI Project's in-water work
window. Similarly, the initial California sea lion and Steller sea lion
densities were based on a single count 40 RM upstream of the project
site, which NMFS deemed unrepresentative of the MSRI Project area.
For the CI Project, incidental take is expected to occur for harbor
seals, California sea lions, and Steller sea lions. Initially, USACE
estimated harbor seal take based on the maximum number of animals
observed on haulout sites 24 and 25 in 2000 (WDFW, 2000). NMFS
determined these data were outdated, as they were over 26 years old.
For California sea lions and Steller sea lions, USACE initially
estimated take based on single count of animals at haulout sites 24 A,
B, and C, as well as pinnipeds counts at Bonneville Dam, located 70 RM
upstream (Edwards, personal communication, 2023, and Braun et. al.,
2024). NMFS does not agree with this approach because historical data,
single counts, and data from Bonneville Dam is unlikely to accurately
reflect current occurrence of pinnipeds at the CI Project area.
Consequently, NMFS proposed, and USACE accepted, revised methodologies
for estimating take for both the MSRI and CI Projects using more recent
and geographically relevant data described below.
[[Page 22516]]
[GRAPHIC] [TIFF OMITTED] TN27AP26.077
Figure 3--Pinniped Haulouts Near the CI Project Area
Previously, NMFS inquired about current marine mammal signings data
from the ODFW in the WDFW in October 2024 for the Interstate Bridge
Replacement Project (90 FR 40492, August 19, 2025). These agencies
provided information about the relative use of haulout areas and the
seasonality of pinniped presence in the Columbia and Willamette Rivers.
This data indicated that peak seasonal presence occurred between the
months of February through May, though sea lions are often present at
Bonneville Dam in other months.
In November 2024, NMFS received unpublished 2012-2020 pinniped
abundance monitoring data for the LCR from ODFW in collaboration with
the Columbia River Inter-Tribal Fish Commission (CRITFC), and ODFW
pinniped monitoring data for 2021-2024 from haulout sites in Columbia,
Willamette, and Kalama Rivers. CRITFC data were taken via boat-based
surveys of known pinniped haulouts along the LCR and the ODFW
monitoring data were taken via boat and aerial drone surveys in the
Columbia, Willamette, and Kalama Rivers at known haulout sites (Brown,
M., Personal communication, 2024). Each of these data sets presented
pinnipeds as a guild, not separated by species.
NMFS analyzed CRITFC datasets for Zone 4 of the Columbia River
Estuary, spanning from Astoria, Oregon river kilometer RM 12 to the
upper end of the estuary RM 41. Although the MSRI Project is expected
to occur between December and February, CRITFC data were only available
from February through May. These data show a seasonal increase in
pinniped abundance starting in February, with a wide range of annual
variability. Given the project's brief 8-day duration, it is possible
that all in-water work could be concentrated at the end of the work
window when pinniped density is highest. To account for this and for
the variability in pinniped sightings between years, NMFS utilized the
monthly 75th percentile of February and March occurrence data pooled,
which were used in take calculations and are presented in table 11.
This methodology ensures that take of pinnipeds reflects this seasonal
trend, specifically accounting for the higher abundance observed in
late February when all construction for the MSRI Project could
potentially occur.
Table 11--Pinniped Occurrence for the Columbia River Between Astoria, OR and the Upper End of the Columbia River
Estuary
----------------------------------------------------------------------------------------------------------------
75th
Monthly Monthly 75th Average for Percentile for
Month average Percentile February and February and
March March
----------------------------------------------------------------------------------------------------------------
February........................................ 10.5 14.3 70.5 79.2
March........................................... 85.5 89.3
----------------------------------------------------------------------------------------------------------------
While the CI Project area (RM 68-72) falls within CRITFC Survey
Zone 3, NMFS believes that the ODFW monitoring data from 2021 through
2024 provides a more scientifically precise representation of pinniped
occurrence
[[Page 22517]]
in the immediate vicinity (Brown, M., Personal communication, 2024).
This dataset captures seasonal variation between January through May,
showing an increase in occurrence that peaks between February and
March. To ensure take estimates accurately reflect seasonal variability
during the CI Project's November through December pile driving window,
NNMFS condensed the monitoring data using the following approach:
<bullet> Averaging Methodology: Monthly counts were compiled to
calculate monthly and 2-month pooled averages (e.g., January/February,
and February/March) to capture peak seasonal occurrence.
<bullet> November/December Proxy: Because specific monitoring data
were unavailable for these months, the January monthly average was used
as a surrogate.
<bullet> January Adjustment: The January/February pooled average
was applied to January project activities to account for increasing
seasonal occurrence.
<bullet> February Adjustment: The February/March pooled average was
applied to February project activities to ensure estimates account for
the late-season peak in occurrence.
The resulting values in table 12 were applied to the Level A
formula for the CI Project below.
Table 12--Pinniped Occurrence for the Cowlitz/Rainier Haulouts Used in
Take Estimation
------------------------------------------------------------------------
Observation month(s)
Construction Month Guild average (moving average(s))
------------------------------------------------------------------------
November....................... 138 January (one-month).
December....................... 138 January (one-month).
January........................ 148 January and February
(two-months).
February....................... 298.15 February and March (two-
months).
------------------------------------------------------------------------
Take Estimation
Here we describe how the information provided above is synthesized
to produce a quantitative estimate of the take that is reasonably
likely to occur and proposed for authorization. Because recent
monitoring data obtained from CRITFC, ODFW, and WDFW often do not
differentiate between pinniped species, NMFS calculated occurrence
rates for the three expected pinniped species as a combined guild.
The predicted isopleths in table 13 differ from those presented in
the original applications because the application's Level A harassment
isopleths were modeled without a bubble curtain. In this proposed
authorization, NMFS applied a 5 dB noise attenuation factor to account
for USACE's use of bubble curtains during impact pile driving.
Not all animals within the MSRI and CI Project areas are expected
to be exposed to noise levels exceeding the threshold for Level A
harassment. NMFS concurs with USACE's proposal to estimate Level A
harassment based on the proportion of the largest pile-driving isopleth
(impact or vibratory) for each pile size relative to the average river
width at the construction site (Table 13).
Table 13--Proportion of Eposure By Activity For Transiting Pinnipeds, Total Days of Pile Installation, and Average Days of Pile Installation Each Month
for the MSRI and CI Projects
--------------------------------------------------------------------------------------------------------------------------------------------------------
Predicted Average Proportion of Days of pile
Installation method \a\ Pile type largest channel width channel width Total days of installation
isopleth (m) (m) ensonified pile driving per month
--------------------------------------------------------------------------------------------------------------------------------------------------------
MSRI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Attenuated Impact Installation \b\...... 24-inch Steel Pipe........ 242 9,918 0.026 8 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
CI Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Unattenuated vibratory installation..... 12-inch timber piles...... 19 969 0.020 17 4.25
Attenuated impact installation \b\...... 10 to 12-inch steel pipe 33 811.4 0.041 11 2.75
piles.
Attenuated impact installation \b\...... 16-inch steel pipe piles.. 93 862 0.108 4 1
Attenuated impact installation \b\...... 24-inch steel pipe........ 60 762 0.079 2 0.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Only the largest harassment zone (impact or vibratory installation) per pile size was included because both methods would occur on the same day and
take was calculated with the largest of the two zones.
\b\ 5 dB of attenuation was applied to impact driving to account for noise reduction from bubble curtains.
MSRI Project: Take Calculation Methods
NMFS used the following formula to calculate take by Level A
harassment for pinnipeds as a guild for the MSRI Project:
Level A harassment= (Largest predicted Level A harassment isopleth (m)/
Average river channel width (m)) x Total days of pile driving x 75th
percentile of 2-month pinniped occurrence (February and March)
For the MSRI Project, the largest Level A harassment isopleth would
occur during impact pile driving of 24-inch steel pipe piles. After
applying the 5 dB attenuation for bubble curtain use, the largest Level
A harassment isopleth for
[[Page 22518]]
the pinniped guild is 242 m. Dividing this by the average channel width
results in an isopleth ratio of 0.026 (table 13).
To calculate the take estimate, this ratio (0.026) was multiplied
by the total duration of pile driving (8 days) and the 75th percentile
of pinniped occurrence for February and March (79.6 animals per day)
from CRITFC Zone 4 surveys. This results in a rounded estimate of 17
takes by Level A harassment. Accordingly, NMFS proposes to authorize 17
takes of pinnipeds by Level A harassment for the MSRI Project,
presented as a guild (tables 14 and 15).
NMFS used the following formula to calculate take by Level B
harassment for the MSRI Project:
Level B harassment = ((total days of pile driving x 75th percentile of
2-month pinniped occurrence (February and March))--Calculated Level A
harassment)
Take by Level B harassment was calculated by multiplying the 8 days
of pile driving for 24-inch steel pipe piles by the 75th percentile of
pooled March/February occurrence (79.6), equating to 634 total pinniped
takes by Level B harassment. After subtracting the 17 takes by Level A
harassment, the result is 617 estimated takes by Level B harassment.
Thus, NMFS proposes to authorize 617 takes by Level B harassment of
pinnipeds presented as a guild (tables 14 and 15).
Table 14--Estimated Take by Level A Harassment and Level B Harassment Proposed for Authorization for Pinnipeds
as a Guild for the MSRI Project
----------------------------------------------------------------------------------------------------------------
Estimated
take November
Pile type (installation or removal method) through Total
December
----------------------------------------------------------------------------------------------------------------
Level A harassment ...................................................
----------------------------------------------------------------------------------------------------------------
24-inch steel pipe (impact)................ 16.8 17
----------------------------------------------------------------------------------------------------------------
Level B harassment Total Level B harassment-Level A harassment
----------------------------------------------------------------------------------------------------------------
24-inch steel pipe (impact)................ 633.6 617
----------------------------------------------------------------------------------------------------------------
Table 15--Proposed take of Marine Mammals by Level A and Level B Harassment and Percent of Each Stock Expected
Take for the MSRI Project
----------------------------------------------------------------------------------------------------------------
Proposed Take--MSRI Project
-------------------------------- Percentage of
Species Stock Level A Level B stock \a\
harassment harassment
----------------------------------------------------------------------------------------------------------------
Harbor Porpoise....................... Northern OR/WA Coast.... 0 2 <1
California Sea Lion................... U.S..................... 17 617 <1
Steller Sea Lion...................... Eastern................. 1.7
Harbor Seal........................... OR/WA Coastal........... 2.8 \b\
----------------------------------------------------------------------------------------------------------------
\a\ NMFS conservatively assumes that all proposed estimated takes could come from a single stock due to the
inability to distinguish between species detected during surveys. In reality, takes would occur to all three
stocks and the percentages shown are thus overestimates.
\b\ The SAR lists the abundance for this stock as unknown; Pearson et al., 2024 report an estimate of 22,549,
which we used in this analysis.
CI Project: Take Calculation Methods
NMFS used the following formula to calculate take by Level A
harassment per pile size/type for the CI project:
Level A harassment (per pile size/type) = (Largest predicted Level A
harassment isopleth (m)/Average river channel width (m)) x Average pile
driving days per month x Monthly or pooled 2-month average pinniped
occurrence
For all pile sizes, except 12-inch timber piles, the largest
predicted Level A harassment isopleth occurs during impact pile
driving. The average river channel width represents the mean of all
pile installation locations (PDs) corresponding to each specific pile
size and type. The average pile driving days is the total number of
days per pile type divided by four, as the in-water work window spans 4
months (December through February) (table 13). USACE assumed that each
pile type would be driven on separate days. Estimates for each pile
size were summed to determine the total takes by Level A harassment for
the CI Project (table 16).
NMFS used the following formula to calculate take by Level B
harassment for the CI Project:
Level B harassment (per pile size/type) = (Average monthly pile driving
days x Monthly or pooled 2-month average of pinniped occurrence)--
Calculated take by Level A harassment
The total Level B harassment for the CI Project was calculated by
summing the estimates for all pile sizes/types and then subtracting the
total estimated takes by Level A harassment (table 16). Total takes
proposed for authorization by Level A and Level B harassment are
presented in table 17.
[[Page 22519]]
Table 16--Take by Level A and Level B Harassment of Pinnipeds as a Guild for Each Pile Size and Total Take for
the CI Project
----------------------------------------------------------------------------------------------------------------
Pile type (installation or Total
removal method) November December January February (rounded)
----------------------------------------------------------------------------------------------------------------
Level A harassment
----------------------------------------------------------------------------------------------------------------
Installation
----------------------------------------------------------------------------------------------------------------
12-inch timber pole (vibratory). 11.5 11.5 12.3 24.8 247
10-12-inch steel pipe (impact).. 15.4 15.4 16.6 33.3
16-inch steel pipe (impact)..... 14.9 14.9 16 32.2
24-inch steel pipe (impact)..... 5.4 5.4 5.8 11.7
----------------------------------------------------------------------------------------------------------------
Level B harassment
----------------------------------------------------------------------------------------------------------------
Installation) Total
(rounded)
----------------------------------------------------------------------------------------------------------------
12-inch timber pole (vibratory). 586.5 586.5 629 1,267.1 11,578
10-12-inch steel pipe (impact).. 379.5 379.5 407 819.9
16-inch steel pipe (impact)..... 138 138 148 298.2
24-inch steel pipe (impact)\a\.. 69 69 74 149.1
24-inch steel pipe 310.5 310.5 333 670.8
(vibratory)\b\.................
24-inch steel sheet 414 414 444 894.5
(vibratory)\b\.................
----------------------------------------------------------------------------------------------------------------
Removal
----------------------------------------------------------------------------------------------------------------
24-inch steel pipe (vibratory) 310.5 310.5 333 670.8
\b\............................
24-inch steel sheet (vibratory) 51.75 51.75 55.5 111.8
\b\............................
----------------------------------------------------------------------------------------------------------------
\a\ Indicates permanent Aid to Navigation (ATON) piles.
\b\ Indicates temporary Material Offload Facility (MOF) pile.
Table 17--Proposed take of Marine Mammals by Level A and Level B Harassment and Percent of Each Stock Expected
Take for the CI Project
----------------------------------------------------------------------------------------------------------------
Proposed Take
-------------------------------- Percentage of
Species Stock Level A Level B Stock \a\
harassment harassment
----------------------------------------------------------------------------------------------------------------
California Sea Lion................... U.S..................... 247 11,758 4.6
Steller Sea Lion...................... Eastern................. 32.6
Harbor Seal \b\....................... OR/WA Coastal........... 52.44
----------------------------------------------------------------------------------------------------------------
\a\ NMFS conservatively assumes that all proposed estimated takes could come from a single stock due to the
inability to distinguish between species detected during surveys. In reality, takes would occur to all three
stocks and likely to the same individuals over subsequent days, and the percentages shown are thus
overestimates.
\b\ The SAR lists the abundance for this stock as unknown; Pearson et al., 2024 report an estimate of 22,549,
which we used in this analysis.
Proposed Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks, and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned), and;
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, impact on
operations.
The mitigation requirements described in the following were
proposed by USACE in its adequate and complete applications or are the
result of subsequent coordination between NMFS and USACE. USACE has
agreed that all of the mitigation measures are practicable. NMFS has
fully reviewed the specified activities and the mitigation measures to
determine if the mitigation measures would result in the least
practicable adverse impact on marine mammals and their habitat, as
[[Page 22520]]
required by the MMPA, and has determined the proposed measures are
appropriate. NMFS describes these below as proposed mitigation
requirements and has included them in the proposed IHAs.
In addition to the measures described later in this section, the
USACE would follow these general mitigation measures:
<bullet> Authorized take, by Level A and Level B harassment only,
would be limited to the species and numbers listed in tables 15 and 17.
Construction activities must be halted upon observation of either a
species for which incidental take is not authorized or a species for
which incidental take has been authorized but the authorized number of
takes has been met, entering or is within the harassment zone.
<bullet> The taking by serious injury or death of any of the
species listed in table 16 or any taking of any other species of marine
mammal would be prohibited and would result in the modification,
suspension, or revocation of the IHAs, if issued. Any taking exceeding
the authorized amounts listed in tables 15 and 17 would be prohibited
and would result in the modification, suspension, or revocation of the
IHAs, if issued.
<bullet> Ensure that construction supervisors and crews, the marine
mammal monitoring team, and relevant USACE staff are trained prior to
the start of all construction activities, so that responsibilities,
communication procedures, marine mammal monitoring protocol, and
operational procedures are clearly understood. New personnel joining
during the projects must be trained prior to commencing work;
<bullet> The USACE, construction supervisors and crews, protected
species observers (PSOs), and relevant USACE staff must avoid direct
physical interaction with marine mammals during construction activity.
If a marine mammal comes within 10 meters of such activity, operations
must cease and vessels must reduce speed to the minimum level required
to maintain steerage and safe working conditions, as necessary to avoid
direct physical interaction;
<bullet> Employ PSOs and establish monitoring locations as
described in Section 5 of the IHAs and the USACE's Marine Mammal
Monitoring and Mitigation Plans (see chapter 10 and chapter 13 of the
USACE MSRI and CI Project applications, respectively). The USACE must
monitor the project area to the maximum extent possible based on the
required number of PSOs, required monitoring locations, and
environmental conditions.
Additionally, the following mitigation measures apply to the
USACE's in-water construction activities at both the MSRI and CI
project locations:
Establishment of Shutdown Zones
The USACE would establish shutdown zones with radial distances as
identified in tables 18 and 19 for all construction activities. The
purpose of a shutdown zone is generally to define an area within which
shutdown of the activity would occur upon sighting of a marine mammal
(or in anticipation of an animal entering the defined area). If a
marine mammal enters or is observed within the shutdown zones indicated
in tables 18 and 19, pile driving must be delayed or halted. Operations
may only resume once the animal is visually confirmed outside the zone
or 15 minutes have passed without a re-detection.
Construction supervisors and crews, PSOs, and relevant USACE staff
must avoid direct physical interaction with marine mammals during
construction activities. If marine mammals come within 10 m of such
activity, operations must cease, to avoid direct interaction. If an
activity is delayed or halted due to the presence of a marine mammal,
the activity may not commence or resume until either the animal has
voluntarily exited and been visually confirmed beyond the shutdown zone
indicated in tables 18 and 19 or 15 minutes have passed without re-
detection of the animal.
Finally, construction activities must be halted upon observation of
a species for which incidental take is not authorized or a species for
which incidental take has been authorized but the authorized number of
takes has been met entering or within any shutdown zone. If a marine
mammal species not covered under these IHAs enters a shutdown zone, all
in-water activities would cease until the animal leaves the zone or has
not been observed for at least 15 minutes. Pile driving may proceed if
the unauthorized species is observed leaving the clearance and shutdown
zone or if 15 minutes have passed since the last observation.
Table 18--Proposed Shutdown Zones During MSRI Project Activities
----------------------------------------------------------------------------------------------------------------
Shutdown zone (m)
Pile type, size, and method or activity -----------------------------------------------
VHF cetaceans PW OW
----------------------------------------------------------------------------------------------------------------
24-inch Steel Pipe, Vibratory Installation...................... 50
-----------------------------------------------
24-inch Steel Pipe, Impact Installation.
Barge Movement and Rock or Pile Placement....................... 10
----------------------------------------------------------------------------------------------------------------
Table 19--Proposed Shutdown Zones During CI Project Activities
------------------------------------------------------------------------
Shutdown zones (m)
Pile type, size, and method or Activity -------------------------------
PW OW
------------------------------------------------------------------------
10-12, 16, and 24 Steel Pipe Piles,
Impact Installation.................... 60
12-inch Timber Pole Pile, Vibratory and
Impact Installation.................... 40
10-12, 16, and 24-inch Steel Pipe Piles,
and 24-inch Steel Sheet Piles,
Vibratory Installation or Removal...... 20
Terrestrial Work at PD 68.35............ 60
Barge Movement and Rock or Pile
Placement.............................. 10
------------------------------------------------------------------------
[[Page 22521]]
Pre- and Post-Activity Monitoring
Monitoring would take place before, during, and 30 minutes after
any pile driving or pile removal activities (i.e., pre-start clearance
monitoring). In addition, monitoring for 30 minutes would take place
whenever a break in the specified activity (i.e., impact pile driving,
vibratory pile driving) of 30 minutes or longer occurs. Pre-start
clearance monitoring would be conducted during periods of visibility
sufficient for the lead PSO to determine that the shutdown zones
indicated in tables 18 and 19 are clear of marine mammals. Pile driving
may commence following 30 minutes of observation when the determination
is made that the shutdown zones are clear of marine mammals. If pile
driving is delayed or halted due to the presence of a marine mammal,
the activities would not commence or resume until either the animal has
voluntarily left and been visually confirmed beyond the shutdown zones
or 15 minutes have passed without re-detection of the animal.
Soft Start Procedures for Impact Driving
Soft-start procedures are used to provide additional protection to
marine mammals by providing warning and/or giving marine mammals a
chance to leave the area prior to an impact hammer operating at full
capacity. The USACE would use soft start techniques when impact pile
driving. Soft start procedures require contractors to provide an
initial set of three strikes at reduced energy, followed by a 30-second
waiting period, then two subsequent reduced- energy strike sets. A soft
start would be implemented at the start of each day's impact pile
driving and at any time following cessation of impact pile driving for
a period of 30 minutes or longer.
Bubble Curtain
A bubble curtain would be employed during impact installation or
proofing of timber or steel piles, unless the piles are driven in the
dry, or water is less than 3 ft (0.9 m) in depth. A bubble curtain
would not be required during vibratory pile driving. At minimum, the
bubble curtain must distribute air bubbles around 100 percent of the
piling perimeter for the full depth of the water column. The lowest
bubble ring would be in contact with the substrate for the full
circumference of the ring. The weights attached to the bottom ring
would ensure 100 percent substrate contact. No parts of the ring or
other objects would prevent full substrate contact. Air flow to the
bubblers must be balanced around the circumference of the pile.
Based on our evaluation of the applicant's proposed measures, NMFS
has preliminarily determined that the proposed mitigation measures
provide the means of effecting the least practicable impact on the
affected species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, and areas of similar
significance. NMFS conducted an independent evaluation of the proposed
measures, and has preliminarily determined for each of the proposed
IHAs that the proposed mitigation measures provide the means of
effecting the least practicable impact on the affected species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present while
conducting the activities. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the activity; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
<bullet> Mitigation and monitoring effectiveness.
The monitoring and reporting requirements described in the
following were
proposed by the USACE in its adequate and complete applications
and/or are the result of
subsequent coordination between NMFS and USACE. USACE has agreed to
the
requirements. NMFS describes these below as requirements and has
included them in the proposed IHAs.
Visual Monitoring
All PSOs must be NMFS-approved and have no other assigned tasks
during monitoring periods. At least one PSO would have prior experience
performing the duties of a PSO during construction activity pursuant to
a NMFS-issued ITA.
During all in-water work for both the MSRI and CI Projects, a
minimum of two PSOs would monitor Level A and Level B harassment zones
to the extent practicable to document the marine mammal's presence and
behavior. PSOs would monitor for marine mammals 30 minutes before,
during, and 30 minutes after the specified activities from the
construction barge, on shore nearby, or from a vessel 200 to 300 m
away. Additionally, observers would record all incidents of marine
mammal occurrence, regardless of distance from activity, and would
document any behavioral reactions in concert with distance from piles
being driven or removed. Pile driving activities include the time to
install or remove a single pile or series of piles, as long as the time
elapsed between uses of the pile driving equipment is no more than 30
minutes.
PSOs should also have the following additional qualifications:
<bullet> Ability to conduct field observations and collect data
according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
[[Page 22522]]
<bullet> Writing skills sufficient to prepare a report of
observations including but not limited to the number and species of
marine mammals observed; dates and times when in-water construction
activities were conducted; dates, times, and reason for implementation
of mitigation (or why mitigation was not implemented when required);
and marine mammal behavior; and
<bullet> 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
The USACE would be required to submit a draft report(s) on all
construction activities and marine mammal monitoring results to NMFS
within 90 days of the completion of monitoring, or 60 days prior to the
requested issuance of any subsequent IHAs or similar activities at the
same locations, whichever comes first. The information required to be
collected and reported to NMFS is included in the draft IHA available
at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. In summary, the
reports would include, but not be limited to, information regarding
activities that occurred, marine mammal sighting data, and whether
mitigative actions were taken or could not be taken. The USACE would
also be required to submit reports on any observed injured or dead
marine mammals. If the death or injury was clearly caused by the
specified activity, the USACE would immediately cease the specified
activities until NMFS is able to review the circumstances of the
incident and determine what, if any, additional measures are
appropriate to ensure compliance with the terms of the IHA. The USACE
would not resume its activities until notified by NMFS.
Specific proposed mitigation, monitoring, and reporting
requirements can be found in the draft IHAs found at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338,
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the majority of our analysis applies to all
the species listed in table 3, given that many of the anticipated
effects of these two projects on different marine mammal stocks are
expected to be relatively similar in nature. There is little
information about the nature or severity of the impacts, or the size,
status, or structure of any of these species or stocks that would lead
to a different analysis for this activity.
NMFS has identified key factors which may be employed to assess the
level of analysis necessary to conclude whether potential impacts
associated with a specified activity should be considered negligible.
These include (but are not limited to) the type and magnitude of
taking, the amount and importance of the available habitat for the
species or stock that is affected, the duration of the anticipated
effect to the species or stock, and the status of the species or stock.
The following factors support negligible impact determinations for all
affected stocks. Additionally, for both projects, pile driving will be
restricted to daylight hours only. This allows animals to transit
through the project areas and use the habitat during nighttime hours
without the potential for noise-related harassment.
Pile driving and removal activities associated with the MRSI and CI
Projects, as outlined previously have the potential to disturb or
displace marine mammals. Specifically, the specified activities may
result in take, in the form of Level A and Level B harassment, from
underwater sounds generated by impact and vibratory pile driving.
Potential takes could occur if individuals are present in the
ensonified zone when these activities are underway.
For the MSRI and CI Projects, take by Level A harassment is
proposed to be authorized for California sea lions, Steller sea lions,
and harbor seals to account for the possibility that an animal could
enter a Level A harassment zone prior to detection, and remain within
that zone for long enough to incur AUD INJ, i.e., minor degradation of
hearing capabilities within regions of hearing that align most
completely with the energy produced by impact and vibratory pile
driving (i.e., the low-frequency region below 2 kilohertz (kHz)), not
severe hearing impairment or impairment within the ranges of greatest
hearing sensitivity. Animals would need to be exposed to higher levels
and/or longer duration than are expected to occur here in order to
incur any more than a small degree of AUD INJ. If hearing impairment
occurs, it is most likely that the affected animal would lose only a
few dB in its hearing sensitivity. Due to the small degree anticipated,
any AUD INJ from Level A harassment potentially incurred is not
expected to impair an individual's ability to communicate, forage, or
detect predators to a level that would impact reproductive success or
survival, much less result in adverse impacts on the species or stock.
For the MSRI Project, NMFS proposes to authorize 17 takes by Level
A harassment across three species/stocks (i.e., California sea lions,
Steller sea lions, and harbor seals), representing a small portion of
each species' stock abundance. Because the ensonified area is
relatively small, confined, and does not span the entire width of the
river channel, animals can transit through the area outside the
ensonified zones or during construction breaks, thereby reducing their
potential for Level A harassment.
For the CI Project, NMFS proposes to authorize 247 takes by Level A
harassment for three pinniped species/stocks (i.e., California sea
lions, Steller sea lions, and harbor seals). Despite the higher number
of takes, this remains a small portion of each species' stock
abundance. Similar to the MSRI project, the ensonified areas for the CI
Project would not span the entire river channel, and the use of non-
consecutive pile driving days provides additional opportunities for
animals to transit the area without harassment.
[[Page 22523]]
As described above, NMFS expects that marine mammals would likely
move away from an aversive stimulus, especially at levels that would be
expected to result in AUD INJ, given sufficient notice through use of
soft start. The USACE would also be required to shut down pile driving
activities if marine mammals approach within hearing group-specific
zones (see tables 17 and 18), further minimizing the likelihood and
degree of AUD INJ and more severe behavioral responses. Even absent
mitigation, no serious injury or mortality from construction activities
is anticipated or proposed to be authorized. Effects on individuals
that are taken by Level B harassment in the form of behavioral
disruption, on the basis of reports in the literature as well as
monitoring from other similar activities, would likely be limited to
reactions such as avoidance, increased swimming speeds, increased
surfacing time, or decreased foraging (if such activity were occurring)
(e.g., Thorson and Reyff 2006). Most likely, individuals would simply
move away from the sound source and temporarily avoid the area where
pile driving is occurring. If sound produced by project activities is
sufficiently disturbing, animals are likely to simply avoid the area
while the activities are occurring, particularly as both project areas
are located along the FNC in the LCR with high amounts of commercial
and recreational vessel traffic. We expect that any avoidance of the
project area by marine mammals would be temporary in nature and that
any marine mammals that avoid the project area during construction
would not be permanently displaced. Pinnipeds on nearby haulouts may
remain on these haulouts for longer or swim with their heads out of the
water more often. Short-term avoidance of the project area and
energetic impacts of interrupted foraging or other important behaviors
is unlikely to affect the reproduction or survival of individual marine
mammals, and the effects of behavioral disturbance on individuals is
not likely to accrue in a manner that would affect the rates of
recruitment or survival of any affected stock. Additionally, and as
noted previously, some subset of the individuals that are behaviorally
harassed could also simultaneously incur some small degree of TTS for a
short duration of time. However, since the hearing sensitivity of
individuals that incur TTS is expected to recover completely within
minutes to hours, it is unlikely that the brief hearing impairment
would affect the individual's long-term ability to forage and
communicate with conspecifics, and would therefore not likely impact
reproduction or survival of any individual marine mammal, let alone
adversely affect rates of recruitment or survival of the species or
stock.
The MSRI and CI Projects are also not expected to have significant
adverse effects on affected marine mammals' habitats. The project
activities would not modify existing marine mammal habitat for a
significant amount of time. The activities may cause some fish to leave
the area of disturbance, thus temporarily impacting marine mammals'
foraging opportunities in a limited portion of the foraging range; but,
because of the short duration of the activities and the relatively
small area of the habitat that may be affected (with no known
particular importance to marine mammals), the impacts to marine mammal
habitat are not expected to cause significant or long-term negative
consequences.
For the MSRI Project area there are no known haulouts or
Biologically Important Areas within the ensonified zones. Marine
mammals are expected to transit through the area during the proposed
activities; therefore, any resulting impacts are expected to be short-
term and minor, given the brief 8 days of pile driving.
In the CI project area, California sea lions, Steller sea lions,
and harbor seals are common and frequently use haulout sites 24 A, B,
and C. While pile installation for PD 68.35 is located approximately
200 m from haulout site 24 A, in-water construction at this site would
be restricted to the month of November when pinnipeds are expected to
be the least prevalent. Monitoring by the ODFW and CRITFC indicate high
seasonal variability in haulout site use, with counts ranging from a
single individual (January and April 2022) to as many as 1,766
pinnipeds (March 2023) (Brown, M., Personal communication, 2024).
Given the implementation of mitigation measures, the availability
of alternative haulout sites in the LCR, the localized nature of
ensonified areas, and the project's short overall duration of pile
driving (66 days), the proposed activities are expected to have a
negligible impact on the affected pinniped stocks.
Additionally, the CI Project area is a very small proportion of the
stocks' overall range, with only a small portion of the overall stock
expected to occur at these haulouts. Consequentially, the requested
take does not represent a broad impact across the entire stock, but
rather repeated exposures to the same individuals. Although the harbor
seals that haul out in the project area may experience short term
exposure to elevated noise levels, such intermittent disturbances,
which are not expected to result in chronic stress or physical injury
that would reduce the fitness, survival, or reproductive success of any
individual. Because the anticipated impacts are localized to a small
subset of the population and are not expected to affect the health of
those individuals, the take proposed for authorization would not reach
a level of biological significance that would affect annual rates of
recruitment or survival for the Oregon/Washington coastal stock of
harbor seals.
In summary and as described above, the following factors primarily
support our preliminary determinations that the impacts resulting from
the two separate specified activities are not expected to adversely
affect any of the species or stocks through effects on annual rates of
recruitment or survival:
<bullet> No serious injury or mortality is anticipated or
authorized;
<bullet> The intensity of anticipated takes by Level B harassment
is relatively low for all stocks and would not be of a duration or
intensity expected to result in impacts on reproduction or survival;
<bullet> The ensonified areas are very small relative to the
overall habitat ranges of all species and stocks, and would not
adversely affect ESA-designated critical habitat for any species or any
areas of known biological importance;
<bullet> The lack of anticipated significant or long-term negative
effects to marine mammal habitat;
<bullet> The availability of nearby areas of similar habitat value
(e.g., foraging and haulout habitats) within and outside the LCR;
<bullet> Impacts on marine mammal feeding are not expected to
result in significant or long-term consequences for individuals, or to
accrue adverse impacts on their populations;
<bullet> The USACE would implement mitigation measures, such as
soft-starts for impact pile driving and shutdowns to minimize the
numbers of marine mammals exposed to injurious levels of sound, and to
ensure that take by Level A harassment, is at most, a small degree of
auditory injury.
<bullet> Previous monitoring reports for similar activities in the
LCR have documented little to no behavioral effect on individuals.
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 for
[[Page 22524]]
each of the proposed IHAs that the total marine mammal take from the
proposed activity will have a negligible impact on all affected marine
mammal species or stocks.
Small Numbers
As noted previously, only take of small numbers of marine mammals
may be authorized under section 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. When the predicted number of
individuals to be taken is fewer than one-third of the species or stock
abundance, the take is considered to be of small numbers (see 86 FR
5322, January 19, 2021). Additionally, other qualitative factors may be
considered in the analysis, such as the temporal or spatial scale of
the activities.
Consistent with the small numbers finding required by the MMPA,
NMFS has determined that the number of individuals proposed for
authorization is small relative to the relevant stock abundances. For
the MSRI Project, the number of takes proposed for all species is well
below one-third of the best available population estimates,
representing less than 1 percent for harbor porpoises and California
sea lions, approximately 1.7 percent for Steller sea lions, and
approximately 2.8 percent for harbor seals.
For the CI Project, the proposed instances of take for California
sea lions (approximately 4.6 percent) and Steller sea lions
(approximately 32.6 percent) are below the one-third threshold.
However, the proposed instances of take for harbor seals (approximately
52.4 percent) are above one-third of the stock. While the total number
of takes proposed for authorization represents a notable portion of the
Oregon/Washington Coastal Stock of harbor seals, the percentage of the
stock presented in table 17 assumes that all takes that were calculated
as a guild, would occur for only harbor seals. However, it is more
likely that take would be split between all three species/stocks of
pinnipeds. Therefore, the proportion of the stock taken is expected to
be much lower than 52 percent.
The percentage of stock in table 17 also assumes that the total
takes proposed for authorization represent unique individuals. This
assumption likely overestimates the number of individual animals
affected. The largest number of pinnipeds documented during ODFW
surveys from 2021 through 2024 was 1,766 individuals, which were not
differentiated by species. If this maximum number of individuals were
present in the project area and consisted entirely of either Steller
sea lions or harbor seals, the resulting take for either stock would be
only approximately 4.9 percent and 7.8 percent, respectively.
Therefore, the actual percentage of individual animals taken would be
significantly less than one-third of the stock abundance for either
species. This finding is further supported by the relatively short
duration of the project (66 days) and the localized nature of the
activities within a very small portion of the stocks' overall range.
Given the short duration and small area of the Columbia River affected
by the CI Project activities, it is highly unlikely that more than one-
third of Steller sea lion and harbor seal stocks would occur in the
area during active pile driving activities and be incidentally taken.
The takes proposed for authorization are expected to involve repeated
exposures of the same individuals as they transit through the area,
rather than affecting a large number of unique animals. Therefore, NMFS
finds that the amount of take proposed for authorization during CI
Project activities represents less than one-third of each of the
affected pinniped stocks.
Based on the analysis contained herein of the proposed activities
(including the proposed mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS preliminarily finds for each
of the proposed IHAs that small numbers of marine mammals would be
taken relative to the population size of the affected species or
stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
Endangered Species Act
Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency ensures that any action it
authorizes, funds, or carries out is not likely to jeopardize the
continued existence of any endangered or threatened species or result
in the destruction or adverse modification of designated critical
habitat. To ensure ESA compliance for the issuance of incidental take
authorizations, NMFS consults internally whenever we propose to
authorize take for ESA-listed species.
No incidental take of ESA-listed species is proposed for
authorization or expected to result from these activities. Therefore,
NMFS has determined that formal consultation under section 7 of the ESA
is not required for these actions.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue two IHAs to USACE for conducting construction at Miller Sands,
Rice, and Cottonwood Islands in the LCR, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated. A draft of the proposed IHAs can be found at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.
Request for Public Comments
We request comment on our analyses, the proposed authorizations,
and any other aspect of this notice of the two proposed IHAs for the
proposed MSRI and CI Projects. We also request comment on the potential
renewal of these proposed IHAs 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 these IHAs or
subsequent renewal IHAs.
On a case-by-case basis, NMFS may issue a one-time, 1-year renewal
IHA following notice to the public providing an additional 15 days for
public comments when (1) up to another year of identical or nearly
identical activities as described in the Description of Proposed
Activity section of this notice is planned or (2) the activities as
described in the Description of Proposed Activity section of this
notice would not be completed by the time the IHA expires and a renewal
would allow for completion of the activities beyond that described in
the Dates and Duration section of this notice, provided all of the
following conditions are met:
<bullet> A request for renewal is received no later than 60 days
prior to the needed renewal IHA effective date (recognizing that the
renewal IHA expiration date cannot extend beyond 1 year from expiration
of the initial IHA).
[[Page 22525]]
<bullet> The request for renewal must include the following:
1. An explanation that the activities to be conducted under the
requested renewal IHA are identical to the activities analyzed under
the initial IHA, are a subset of the activities, or include changes so
minor (e.g., reduction in pile size) that the changes do not affect the
previous analyses, mitigation and monitoring requirements, or take
estimates (with the exception of reducing the type or amount of take).
2. A preliminary monitoring report showing the results of the
required monitoring to date and an explanation showing that the
monitoring results do not indicate impacts of a scale or nature not
previously analyzed or authorized.
<bullet> 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: April 23, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-08153 Filed 4-24-26; 8:45 am]
BILLING CODE 3510-22-P
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