Takes of Marine Mammals Incidental to Specified Activities; Construction of the Parsons Slough Sill Project, 74687-74693 [2010-30235]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 75, Number 230 (Wednesday, December 1, 2010)]
[Notices]
[Pages 74687-74693]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-30235]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XY30


Takes of Marine Mammals Incidental to Specified Activities; 
Construction of the Parsons Slough Sill Project

AGENCY: National Marine Fisheries Service, National Oceanic and 
Atmospheric Administration, Commerce.

ACTION: Notice; issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the Marine Mammal Protection Act (MMPA) 
regulations, notification is hereby given that NMFS has issued an 
Incidental Harassment Authorization (IHA) to the NOAA Restoration 
Center, Southwest Region, to take, by Level B Harassment only, small 
numbers of harbor seals (Phoca vitulina richardsi) incidental to pile 
driving associated with the Parsons Slough Sill Project.

DATES: Effective November 24, 2010, through February 28, 2011.

ADDRESSES: A copy of the IHA, the application, and the associated 
Environmental Assessment and Finding of No Significant Impact are 
available by writing to P. Michael Payne, Chief, Permits, Conservation 
and Education Division, Office of Protected Resources, National Marine 
Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910 or 
by telephoning the contact listed here (see FOR FURTHER INFORMATION 
CONTACT), or visiting the Internet at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications. Documents cited in this notice may 
be viewed, by appointment, during regular business hours, at the 
aforementioned address.

FOR FURTHER INFORMATION CONTACT: Brian D. Hopper or Candace Nachman, 
Office of Protected Resources, NMFS, (301) 713-2289, or Monica 
DeAngelis, NMFS Southwest Region, (562) 980-3232.

SUPPLEMENTARY INFORMATION: 

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce to allow, upon request, the 
incidental, but not intentional, taking of small numbers of marine 
mammals by U.S. citizens who engage in a specified activity (other than 
commercial fishing) within a specified geographical region if certain 
findings are made and either regulations are issued or, if the taking 
is limited to harassment, a notice of a proposed authorization 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), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings 
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103 
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.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the U.S. can apply for an authorization to 
incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of 
an application followed by a 30-day public notice and comment period on 
any proposed authorization published in the Federal Register for the 
incidental harassment of marine mammals. Within 45 days of the close of 
the comment period, NMFS must either issue or deny the authorization.
    Except with respect to certain activities not pertinent here, 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].

Summary of Request

    NMFS received an application on August 5, 2010, from the NOAA 
Restoration Center, Southwest Region, for the taking, by harassment, of 
marine mammals incidental to the construction of a partially submerged 
tidal barrier (sill) across the mouth of the Parsons Slough Channel. 
Parsons Slough is located on the southeast side of the Elkhorn Slough 
Estuary, which is situated 90 miles (145 km) south of San Francisco and 
20 miles (32 km) north of Monterey in Monterey County, California. The 
application was determined to be complete on August 16, 2010. Pile 
driving during the project may result in harassment of Pacific

[[Page 74688]]

harbor seals (Phoca vitulina richardsi) located in the action area. In 
accordance with MMPA implementing regulations, NMFS issued a notice in 
the Federal Register on October 5, 2010 (75 FR 61432), requesting 
comments from the public on the proposed IHA.
    The specified activities are also likely to result in the take by 
incidental harassment of southern sea otters (Enhydra lutirs). The US 
Fish and Wildlife Service (USFWS) has management jurisdiction over 
southern sea otters. NOAA received a separate MMPA Section 101(a)(5)(D) 
authorization for incidental take of sea otters from USFWS. The 
potential take of sea otters is not further addressed in this notice.

Description of the Specified Activity

    A complete description of the specified activity may be found in 
NMFS' proposed IHA notice in the Federal Register (75 FR 61432) and a 
summary is provided here.
    In order to reduce tidal scour, the NOAA Restoration Center, 
Southwest Region, proposes to construct a partially submerged tidal 
barrier (sill), similar to an underwater wall, across the mouth of 
Parsons Slough. The sill structure would prevent head cutting (i.e., 
erosion in a channel caused by an abrupt change in slope) in Elkhorn 
Slough from migrating upstream into Parsons Slough, would retain 
sediment that accretes within Parsons Slough, and would reduce the 
tidal prism of Parsons Slough. This reduction in tidal prism would 
reduce current velocities between Parsons Slough and the mouth of 
Elkhorn Slough, thereby reducing tidal scour. The proposed project, 
which is referred to as the Parsons Slough Project, would also include 
establishment of artificial reefs to support populations of Olympia 
oysters (Ostrea lurida) in the northeastern part of the Parsons Slough 
Complex.
    The sill structure would be constructed of steel sheet piles that 
would extend 270 ft (82.3 m) across the mouth of the Parsons Slough 
Channel. A 100 ft (30 m) wide lower area, located in the center of the 
structure, would allow water to flow between Parsons Slough and Elkhorn 
Slough. This portion of the structure would be submerged more than 99 
percent of the time. The center of the lower part of the structure 
would include a notch approximately 25 ft (7.6 m) wide, with the top 
elevation of the sheet pile in this notch at an elevation of -5 ft (-
1.5 m). The notch would provide for the passage of water at all tide 
levels and would facilitate the movement of fish and wildlife into and 
out of Parsons Slough. The top elevation of the sheet pile in the 
remaining 75 ft (23 m) of the central section of the base structure 
would be -2 ft (-0.6 m). The remaining portions of the sheet piles to 
the left and right of the center portion of the structure would have a 
top elevation of 9.6 ft (3 m).
    All in-channel construction activities would be constructed from 
barges, and no heavy equipment would enter the channels. Most of these 
construction activities are in-water (e.g., installation of end-bearing 
piles and sheet piles, placement of rockfill buttress).
    Installation of the sheet pile wall would be supported by two rows 
of seven end-bearing piles, as well as a single row of sheet pile 
located between the piles. The end-bearing piles would be driven 
through the soft soils to penetrate 10 ft (3 m) below the top of the 
dense sandy deposits that underlie the soft soils at an elevation of 
approximately -80 ft (-24.4 m). Additionally, up to 45 temporary end-
bearing piles may be installed in the main channel of Elkhorn Slough at 
the Kirby Park staging site (approximately 2 mi (3.2 km) from the 
project site) to facilitate barge docking and loading (if the temporary 
dock is constructed on pilings, rather than temporary rock-fill). These 
piles, if necessary, would be removed after construction when the 
floating dock is disassembled. Pile driving at the staging site is not 
expected to result in any harbor seal takes. Harbor seals usually occur 
just beyond the mouth of Elkhorn Slough in the Moss Landing harbor and 
in the Salinas River channel south of the Moss Landing Bridge, and the 
lower portion of Elkhorn Slough extending up to Parsons Slough and 
Rubis Creek. Harbor seals do not typically use the part of the estuary 
that leads up to Kirby Creek and the nearest occupied areas and haul-
out locations (approximately 2 mi (3.2 km to the south) are beyond the 
estimated distances to NMFS' current threshold sound levels from pile 
driving proposed at the Kirby Park staging area (see Table 3 and Table 
4).
    A vibratory hammer would be used to start driving all sheet pile 
and end-bearing piles, but an impact hammer may be required to complete 
driving. If an impact hammer is required during construction, 
cushioning blocks would be used to attenuate the sound. Vibratory 
hammers clamp onto the sheet pile; therefore, no cushioning blocks 
would be used during vibratory pile driving.

                      Table 1--Typical Near-Source
                     (10 M) Underwater Noise Levels
------------------------------------------------------------------------
           Type of pile             Driving  technique      RMS level
------------------------------------------------------------------------
H-Pile...........................  Impact Hammer......  183 dB.
H-Pile...........................  Vibratory Hammer...  155 dB.
Sheet Pile.......................  Impact Hammer......  175 dB.
Sheet Pile.......................  Vibratory Hammer...  160 dB.
------------------------------------------------------------------------


                      Table 2--Airborne Noise Level
                                 (15 M)
------------------------------------------------------------------------
           Type of pile             Driving technique    Lmax/rms level
------------------------------------------------------------------------
H-Pile...........................  Impact Hammer......  109 dBA.
H-Pile...........................  Vibratory Hammer...  95 dBA.
Sheet Pile.......................  Impact Hammer......  106 dBA.
Sheet Pile.......................  Vibratory Hammer...  97 dBA.
------------------------------------------------------------------------

    The applicant anticipates that construction would last 11 to 15 
weeks beginning around November 2010 and ending in February 2011. In-
water construction would primarily occur during slack tide. Actual pile 
driving time during this work window will depend on a number of 
factors, such as sediments, currents, presence of marine mammals, and 
equipment maintenance; however, the applicant anticipates that it will 
take approximately 20 days to install the end-bearing piles and sheet 
pile during the 11 to 15 weeks of construction. Construction activities 
at night are also anticipated during this 11 to 15 week period but 
would not last for more than 5 hrs at a time (duration of a slack tide 
at night).

Comments and Responses

    A notice of receipt and request for public comments on the 
application and proposed authorization was published on October 5, 2010 
(75 FR 61432). During the 30-day public comment period, NMFS received 
comments from the Marine Mammal Commission (Commission) on the proposed 
IHA. No comments were received from any other members of the public.
    Comment 1: The Commission recommended that NMFS require the 
applicant use location-specific environmental parameters to re-estimate 
safety zones and then use in-situ measurements to verify and, if need 
be, refine the safety zone prior to or at the beginning of sill 
construction.

[[Page 74689]]

    Response: Because the estimated source levels of the vibratory pile 
drivers are 30-35 dB below 190 dB, NMFS is confident that the sound 
produced during vibratory pile driving will not approach the threshold 
for Level A harassment of pinnipeds (190 dB re: 1 microPa (rms)). 
Therefore, NMFS will not require a sound verification study during 
vibratory pile driving. However, with respect to impact pile driving, 
NMFS will require the applicant to conduct a sound verification study 
to ensure that the safety zone is adequate to prevent exposing 
pinnipeds to sound levels that may result in Level A harassment.
    Comment 2: The Commission recommended that NMFS require that 
observations be made during all soft-starts to gather the data needed 
to analyze and report on its effectiveness as a mitigation measure.
    Response: NMFS agrees that the NOAA Restoration Center, Southwest 
Region, needs to monitor for marine mammals during all soft-starts. 
PSOs will be on-site and monitoring for marine mammals at least 30 
minutes prior to, during, and after all construction activities 
(including during soft-starts for pile driving). NMFS believes that 
these monitoring requirements will allow for adequate interpretation of 
how marine mammals behave in response to pile driving, including soft-
starts.

Description of Marine Mammals in the Area of the Specified Activity

    Marine mammals with confirmed occurrences in Parsons Slough are 
Pacific harbor seals and southern sea otters (Enhydra lutirs). However, 
southern sea otters are managed by the USFWS and will not be considered 
further in this IHA notice. Information on Pacific harbor seals was 
provided in the October 5, 2010 (75 FR 61432) Federal Register notice.

Potential Effects of the Specified Activity on Marine Mammals

    Pile driving at the site of the proposed sill may temporarily 
impact marine mammal behavior within the action area due to elevated 
noise levels both in-air and in-water. A detailed description of 
potential impacts to marine mammals can be found in NMFS' October 5, 
2010 Federal Register notice (75 FR 61432) and are summarized here.
    Marine mammals produce sounds in various contexts and use sound for 
various biological functions including, but not limited to: (1) Social 
interactions; (2) foraging; (3) orientation; and (4) predator 
detection. Interference with producing or receiving these sounds may 
result in adverse impacts. Audible distance, or received levels (RLs) 
will depend on the nature of the sound source, ambient noise 
conditions, and the sensitivity of the receptor to the sound 
(Richardson et al., 1995). Type and significance of marine mammal 
reactions to noise are likely to be dependent on a variety of factors 
including, but not limited to, the behavioral state (e.g., feeding, 
traveling, etc.) of the animal at the time it receives the stimulus, 
frequency of the sound, distance from the source, and the level of the 
sound relative to ambient conditions (Southall et al., 2007).

Hearing Impairment

    Temporary or permanent hearing impairment is possible when marine 
mammals are exposed to very loud sounds. Temporary threshold shift 
(TTS) and permanent threshold shift (PTS). Relationships between TTS 
and PTS have not been studied in marine mammals, but are assumed to be 
similar to those in humans and terrestrial mammals. There is no 
empirical data for onset of PTS in any marine mammal, therefore, PTS-
onset must be estimated from TTS-onset measurements and from the rate 
of TTS growth with increasing exposure levels above those eliciting 
TTS-onset. NMFS presumes PTS to be likely if the threshold is reduced 
by >= 40 dB (i.e., 40 dB of TTS). Due to required mitigation measures 
and the fact that source levels of the impact and vibratory hammers are 
below the 190 dB injury threshold used by NMFS for pinniped species, 
NMFS does not expect that harbor seals will be exposed to levels that 
could elicit PTS or even mild TTS.

Behavioral Impacts

    The source of underwater noise during construction would be pile 
driving to install the end-bearing piles and sheet pile tidal barrier. 
There are limited data available on the effects of non-pulse noise on 
pinnipeds in-water; however, field and captive studies to date 
collectively suggest that pinnipeds do not strongly react to exposure 
between 90-140 dB re 1 microPa.
    Seals exposed to sound levels that exceed the Level B harassment 
threshold (120 dB for non-pulse; 160 dB for pulse) may exhibit 
temporary avoid behavior around the Union Pacific Railroad bridge, 
which may affect movement of seals under the bridge or inhibit them 
from resting at haul-out sites near the bridge. The estimated 11-15 
weeks required for construction may result in the temporary abandonment 
of haul-out sites near the bridge and within Parsons Slough. Although 
harbor seals may temporarily abandon haul out sites, there are an 
abundance of other haul-out sites in the area. Additionally, the 
required mitigation measures restrict construction to the non-breeding 
season to avoid impacts to potentially sensitive mother-pup pairs. In 
general, ambient noise levels in the area are low; however, animals in 
the vicinity of the project site have been exposed to various types and 
levels of anthropogenic noise from recreational boating to the15-20 
trains that pass daily over the Union Pacific Railroad bridge. Harbor 
seals have also been exposed to in-water construction activities at the 
site and animals are likely tolerant or habituated to anthropogenic 
disturbance, including pile driving. For example, in October 2002, the 
Union Pacific Railroad replaced the existing wooden pile trestle bridge 
spanning the Parsons Slough Channel with a 165 ft (50.3 m) slab girder 
bridge. Biological monitors reported that harbor seals were present 
during construction and came and went from the site without any visible 
signs of stress or undue harassment (MACTEC Engineering and Consulting, 
2003).
    Based on these studies and monitoring reports, NMFS has determined 
that harbor seals exposed to sound levels exceeding the Level B 
harassment thresholds (120 dB for non-pulse; 160 dB for pulse) may 
exhibit temporary avoidance behavior. The most likely impact to harbor 
seals from the sheet pile and end-bearing pile installation would be 
temporary disruption of resting patterns because individual harbor 
seals may abandon haul out sites and leave the area during construction 
activities. However, the scheduling of construction activities during 
the non-breeding season will avoid more severe effects, such as reduced 
pup survival due to mother-pup separation and interrupted suckling 
bouts. Temporary hearing loss is unlikely for those harbor seals that 
enter into the zone of Level B harassment because source levels from 
vibratory pile driving are not loud enough to induce TTS. Furthermore, 
the short duration of impact pile driving and close proximity to the 
source necessary to induce TTS makes it unlikely that harbor seals 
would be exposed to source levels loud enough to induce TTS. Permanent 
hearing loss or other harm is not anticipated due to monitoring and 
mitigation efforts (described below) and the low source levels of pile 
driving hammers to be used in this project; however, even without 
mitigation measures, it is unlikely that harbor seals would experience 
Level A harassment,

[[Page 74690]]

serious injury, or mortality because of the close proximity to the 
source necessary to induce these types of impacts and the avoidance 
behavior expected of harbor seals during pile driving activities.

Anticipated Effects on Habitat

    A detailed description of the anticipated effects on habitat can be 
found in NMFS' October 5, 2010 Federal Register notice (75 FR 61432) 
and are summarized here.
    The action would permanently alter habitat within the project 
footprint; however, harbor seals haul-out in many locations throughout 
the estuary, and the action is not expected to have any habitat-related 
effects that could cause significant or long-term consequences for 
individual harbor seals or their population. Long-term operation of the 
sill is expected to result in the conversion of intertidal habitat to 
subtidal habitat, which will have no adverse effect and possibly a 
long-term beneficial effect on harbor seals by improving ecological 
function of the slough, such as higher species diversity, more species 
abundance, larger fish, and better habitat. It is unlikely that the 
sill structure itself, when completed, will result in long-term adverse 
effects on harbor seal movements through the slough because the sill 
structure allows for continued access to Parsons Slough by aquatic 
species, including harbor seals. Harbor seals and forage fish may 
occupy the same habitat, and harbor seal distributions within the 
estuary reflect foraging locations to some extent. Noise from pile-
driving would result in degradation of in-water habitat; however, this 
impact would be short term and site-specific, and habitat conditions 
would return to their pre-disturbance state shortly after the cessation 
of in-water construction activities. NMFS has determined that the 
project is not expected to have any habitat-related effects that could 
cause significant or long-term consequences for individual marine 
mammals or the food sources that they utilize.

Mitigation Measures

    In order to issue an incidental take authorization (ITA) under 
Section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible 
methods of taking pursuant to such activity, and other means of 
effecting the least practicable impact on such species or stock and its 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance, and on the availability of such species 
or stock for taking for certain subsistence uses (where relevant).
    The applicant has proposed mitigation measures in their application 
for reducing impacts to environmental resources. For example, 
installing end-bearing piles and sheet pile with a vibratory hammer 
instead of an impact hammer will introduce less sound into the marine 
environment and prevent marine mammals from being exposed to injurious 
levels of sound. Some of the following mitigation measures were 
developed by the NOAA Restoration Center, Southwest Region, and 
accepted by NMFS while others were developed in discussions between the 
applicant and NMFS' Office of Protected Resources. These required 
mitigation measures are designed to eliminate the potential for injury 
and reduce Level B harassment of marine mammals.

Establishment of Safety Zones and Shut Down Requirements

    Vibratory pile driving does not result in source levels that are at 
or above NMFS' harassment threshold for Level A harassment; therefore, 
shut down zones would not be required for vibratory pile driving. For 
impact pile driving, the isolpleth for the Level A harassment threshold 
(190 dB re 1 microPa rms) is modeled to be within 10 ft (3 m) of end-
bearing piles driven with an impact hammer and 5 ft (1.5 m) of sheet 
piles driven with an impact hammer. The NOAA Restoration Center, 
Southwest Region, will delay impact pile driving if a harbor seal comes 
within 33 ft (10 m) of the pile being driven, which further reduces the 
risk of Level A harassment. In addition, if an impact hammer is 
required during construction, cushioning blocks will be used to help 
attenuate the sound. At the commencement of impact pile driving, the 
NOAA Restoration Center, Southwest Region, will conduct in-water 
acoustic monitoring for the purpose of verifying the estimated safety 
zones. Based on acoustic monitoring data collected during impact pile 
driving, the NOAA Restoration Center, Southwest Region, may establish a 
new safety zone where sound levels do not exceed 190 dB rms. Finally, 
under the terms of the IHA issued by the USFWS, in-air sound levels 
associated with construction activities will also be monitored.

Construction Timing

    Pile driving is anticipated to occur during an 11 to 15 week period 
beginning in November 2010, and ending in February 2011. This work 
window was selected to coincide with the non-pupping season for harbor 
seals and avoid haul-out site abandonment during pupping season that 
may result in reduced pup survival due to mother/pup separation and 
interrupted suckling bouts. The work window also coincides with the 
USFWS' required construction work window to avoid the peak pupping 
period for sea otters (75 FR 42121, July 20, 2010). In addition, in-
water construction activities such as pile driving will be conducted 
during high tide when haul-out sites are inaccessible, and harbor seals 
are largely absent from Parsons Slough (Maldini et al., 2009).

Limited Use of Impact Hammer

    All piles will be installed using a vibratory pile driver unless 
sufficient depth cannot be reached, at which point an impact hammer may 
be used. If an impact hammer is required, cushioning blocks will be 
used as an attenuation device to reduce hydroacoustic sound levels and 
avoid the potential for injury. These actions would also serve to 
reduce impacts to harbor seals.

Mitigation Monitoring

    Monitoring during construction of the sill will occur from an 
observation post adjacent to the Union Pacific railroad bridge as well 
as from a zodiac. Monitoring will be conducted by qualified, NMFS-
approved protected species observers (PSOs). On a daily basis, 
construction monitoring will begin 30 minutes prior to the initiation 
of construction activities and continue until 30 minutes after 
construction activities have ceased for the day. The PSO will maintain 
a log that documents numbers of marine mammals present before, during, 
and at the end of daily construction activities. In addition, the PSO 
will record basic weather conditions (ambient temperature, tidal 
activity, precipitation, wind, horizontal visibility, etc.), as well as 
marine mammal behavior.
    The PSO will have the authority to cease construction if a harbor 
seal is detected within or approaching the safety zone or if an animal 
appears injured. Within 30 days of the completion of the sill 
construction, a report will be completed and submitted to NMFS that 
will include a summary of the daily log maintained by the PSO during 
construction. In addition, the report will include an assessment of the 
number of harbor seals that may have been harassed as a result of pile 
driving activities, based on direct observation of harbor seals 
observed in the area.

Soft Start to Pile Driving Activities

    A ``soft start'' technique will be used at the beginning of each 
pile installation to allow any harbor seals that may be in the 
immediate area to leave before the

[[Page 74691]]

activity reaches its full energy. The soft start requires contractors 
to initiate pile driving with a vibratory hammer for 15 seconds at 
reduced energy followed by a 1-minute waiting period. This procedure 
will be repeated two additional times. Due to the short duration of 
impact pile driving (typically lasting between 1 and 10 minutes), the 
traditional ramp-up requirement does not apply because it actually 
increases the duration of noise emitted into the environment, and 
monitoring should effectively detect harbor seals within or near the 
proposed impact pile driving shut down zone. If any harbor seals are 
sighted within or approaching the 33 ft (10 m) shut down zone prior to 
pile driving, the construction contractor will delay pile-driving until 
the animal has moved outside and is on a path away from the safety zone 
or after 15 minutes have elapsed since the last sighting.
    NMFS has carefully evaluated the applicant's mitigation measures. 
NMFS accepted some of the applicant's measures, such as the seasonal 
timing of construction, suggested additional mitigation measures like 
the establishment of a 33 ft (10 m) safety zone and hydroacoutic 
monitoring to measure sound pressure levels from pile driving, and 
considered a range of other measures in the context of ensuring that 
NMFS prescribes the means of effecting the least practicable impact on 
the affected marine mammal species and stocks and their habitat. Our 
evaluation of potential measures included consideration of the 
following factors in relation to one another: (1) The manner in which, 
and the degree to which, the successful implementation of the measure 
is expected to minimize adverse impacts to marine mammals; (2) the 
proven or likely efficacy of the specific measure to minimize adverse 
impacts as planned; and (3) the practicability of the measure for 
applicant implementation.
    Based on our evaluation of the applicant's measures, as well as 
other measures developed by NMFS in cooperation with the applicant, 
NMFS has determined that the required mitigation measures provide the 
means of effecting the least practicable impact on marine mammal 
species or stocks and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance.

Monitoring and Reporting

    In order to issue an ITA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must, where applicable, 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 ITAs must include the suggested means of 
accomplishing the necessary monitoring and reporting that will result 
in increased knowledge of the species and of the level of taking or 
impacts on populations of marine mammals that are expected to be 
present in the action area.
    Monitoring during construction of the sill would occur from an 
observation post adjacent to the Union Pacific railroad bridge, as well 
as from a zodiac. Monitoring would be conducted by qualified, NMFS-
approved PSOs. On a daily basis, construction monitoring would begin 30 
minutes prior to the initiation of construction activities and continue 
until 30 minutes after construction activities have ceased for the day. 
The PSO would maintain a log that documents numbers of marine mammals 
present before, during, and at the end of daily construction 
activities. In addition, the PSO would record basic weather conditions 
(ambient temperature, tidal activity, precipitation, wind, horizontal 
visibility, etc.), as well as marine mammal behavior.
    The PSO would have the authority to cease construction if a harbor 
seal is detected within or approaching the safety zone or if an animal 
appears injured. Within 30 days of the completion of the sill 
construction, a report would be completed and submitted to NMFS that 
would include a summary of the daily log maintained by the PSO during 
construction. In addition, the report would include an assessment of 
the number of harbor seals that may have been harassed as a result of 
pile driving activities, based on direct observation of harbor seals 
observed in the area.

Estimated Take by Incidental Harassment

    Except with respect to certain activities not pertinent here, 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 stock in the wild by causing 
disruption of behavioral patterns, including but not limited to, 
migration, breathing, nursing, breeding, feeding, or shelter [Level B 
harassment].
    Based on the NOAA Restoration Center, Southwest Region's 
application and subsequent analysis, the impact of the described pile 
driving operations may result in, at most, short-term modification of 
behavior by small numbers of harbor seals within the action area. 
Harbor seals may avoid the area or halt any behaviors (e.g., resting) 
when exposed to anthropogenic noise. Due to the abundance of suitable 
resting habitat available in the greater Elkhorn Slough estuary, the 
short-term displacement of resting harbor seals is not expected to 
affect the overall fitness of any individual animal.
    Current NMFS practice regarding in-water exposure of marine mammals 
to anthropogenic noise is that in order to avoid the potential for 
injury of marine mammals (e.g., PTS), pinnipeds should not be exposed 
to sounds of 190 dB rms or above. This level is considered 
precautionary as it is likely that more intense sounds would be 
required before injury would actually occur (Southall et al., 2007). 
Potential for behavioral harassment (Level B) is considered to have 
occurred when marine mammals are exposed to sounds at or above 160 dB 
rms for impulse sounds (e.g., impact pile driving) and 120 dB rms for 
non-pulse noise (e.g., vibratory pile driving), but below the 
thresholds mentioned above. These levels are considered to be 
precautionary.
    Current NMFS practice regarding in-air exposure of pinnipeds to 
noise generated from human activity is that the onset of Level B 
harassment for harbor seals is 90 dB rms re 20 microPa. In-air noise 
calculations from using an impact pile driver predict that noise levels 
will reach 90 dB rms re 20 microPa within 600 ft (183 m) for end-
bearing piles and 450 ft (137 m) for sheet piles. For installation 
using a vibratory hammer, noise levels will reach 90 dB rms within 100 
ft (30 m) of the end-bearing pile and 120 ft (36.6 m) for sheet pile. 
Harbor seals are known to haul-out on the mudflats 200 ft (61 m) east 
of the work site and 680 ft (207 m) west of the work site, therefore, 
in-air noise may contribute to harassment for the proposed action.
    Estimated distances to NMFS' current threshold sound levels from 
pile driving during the Parsons Slough Sill Project are presented in 
Table 3 below. These estimates are based on the worst case scenario of 
driving the H-piles and sheet piles but would be carried over for all 
pile driving. Note that despite short distances to the Level A 
harassment isolpleth, the NOAA Restoration Center, Southwest Region, 
will implement a 10 m safety zone until empirical pile driving 
measurements can be made and distances to this threshold isopleths can 
be verified.

[[Page 74692]]



   Table 3--Underwater Distances to NMFS Harassment Threshold Levels During Pile Driving (dB re: 1[mu]Pa rms)
----------------------------------------------------------------------------------------------------------------
                                                                          Sound levels (rms)
            Pile type                 Hammer type    -----------------------------------------------------------
                                                            190 dB              160 dB              120 dB
----------------------------------------------------------------------------------------------------------------
H-Piles.........................  Impact............  3 m (10 ft).......  227 m (745 ft)....  n/a.
H-Piles.........................  Vibratory.........  0.................  n/a...............  1,140 m (3,740
                                                                                               ft).
Sheet Pile......................  Impact............  1.5 m (5 ft)......  75 m (245 ft).....  n/a.
Sheet Pile......................  Vibratory.........  0.................  n/a...............  2,256 m (7,400
                                                                                               ft).
----------------------------------------------------------------------------------------------------------------


 Table 4--Airborne Distances to NMFS Harassment Threshold Levels During
                   Pile Driving (dB re: 20[mu]Pa rms)
------------------------------------------------------------------------
                                                       Sound level (rms)
            Pile type                 Hammer type     ------------------
                                                             90 dB
------------------------------------------------------------------------
H-Piles.........................  Impact.............  600 m.
H-Piles.........................  Vibratory..........  100 m.
Sheet Pile......................  Impact.............  450 m.
Sheet Pile......................  Vibratory..........  120 m.
------------------------------------------------------------------------

    It is difficult to estimate the number of harbor seals that could 
be affected by the installation of end-bearing piles and sheet pile 
because the animals only venture in the project areas to haul-out 
during the day when the tide is low. In-water construction will occur 
near several haul-out sites and, although the construction activities 
are planned to take place during slack tide (some of which will be on 
either side of high tide, when harbor seals are less likely to be 
present), there may still be animals exposed to sound from pile driving 
even if the number of individual harbor seals expected to be 
encountered is very low. These individuals would most likely be adult 
males and females, as well as juveniles. The NOAA Restoration Center, 
Southwest Region requests, and NMFS proposes, authorization to take 
2,000 individual harbor seals incidental to pile driving activities 
over the course of the project (November XX, 2010 through February 28, 
2011). This is an estimate based on the average number of harbor seals 
that occupy Parsons Slough during the day (100) multiplied by the total 
number of days the applicant expects pile driving activities to occur 
(20 days). NMFS considers this to be an over-estimate for the following 
reasons: (1) As mentioned above, haul-out sites are inaccessible to 
harbor seals during high tide, and NMFS would not expect harbor seals 
to be affected by pile driving activities during the days/times when 
pile driving and high tide events co-occur; (2) harbor seals are likely 
absent from Parsons Slough at night when they are likely foraging in 
Monterey Bay and will not be exposed to sound generated during pile 
driving that is proposed to take place in the evening hours (no more 
than 5 hrs at a time); and, (3) based on previous survey effort 
conducted in Parsons Slough, harbor seals would move out of the 
disturbance area when construction activities are initiated and move 
west (downstream) towards Seal Bend until the end of construction.

Negligible Impact and Small Numbers Analysis and Determination

    The regulations implementing the MMPA found at 50 CFR 216.103 
define ``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. In making a negligible impact 
determination, NMFS considers a variety of factors, including but not 
limited to: (1) The number of anticipated mortalities (none of which 
would be authorized here); (2) the number and nature of anticipated 
injuries (none of which would be authorized here); and (3) the number, 
nature, and duration of Level B harassment, and the context in which 
the takes occur (e.g., will the takes occur in an area or time of 
significance for harbor seals, are takes occurring to a small, 
localized population?).
    As described above, harbor seals will not be exposed to activities 
or sound levels which will result in injury (e.g., PTS), serious 
injury, or mortality. Takes will be limited to Level B behavioral 
harassment. Pile driving will take place in the relatively shallow 
estuarine waters of Elkhorn Slough and affect harbor seals that belong 
to a stock that occurs throughout California. Although two harbor seal 
haul-outs are located within 300-400 ft of the action area (waters 
around the Union Pacific Railroad bridge), the Parsons Slough Complex 
is not considered to be an important habitat for harbor seals compared 
to other sites in the area (e.g. Seal Bend). NMFS has determined that 
no injuries or mortalities are anticipated to occur as a result of the 
proposed action, and none are to be authorized. In addition, harbor 
seals in the area are not expected to incur hearing impairment (i.e., 
TTS or PTS) or non-auditory physiological effects. Although it is 
possible for some individual harbor seals to be exposed to sounds from 
pile driving activities more than once, the extent of these multi-
exposures are expected to be limited by the constant movement of harbor 
seals in and out of Elkhorn Slough and the timing of in-water 
construction to coincide with periods when the animals are less likely 
to be present.
    Pacific harbor seals are not listed as depleted under the MMPA or 
threatened or endangered under the Endangered Species Act (ESA). 
Although populations of Pacific harbor seals were greatly depleted by 
the end of the 19th century due to commercial hunting, the population 
has increased dramatically during the last half of the 20th century and 
appears to be stabilizing at what may be their carrying capacity 
(Caretta et al., 2009). The amount of take the NOAA Restoration Center, 
Southwest Region, requests, and NMFS authorizes is considered small 
(less than 6 percent) relative to the estimated population of 34,233 
Pacific harbor seals.

[[Page 74693]]

    Pacific harbor seals may be temporarily impacted by pile driving 
noise. However, these animals are expected to avoid the area, thereby 
reducing exposure and impacts. In addition, although the sill project 
is expected to take 11 to 15 weeks to complete, the installation of 
end-bearing piles and sheet pile would only occur for approximately 20 
days. Further, the Union Pacific Railroad bridge that is located in the 
vicinity of the project site has approximately 15-20 trains passing 
over it each day and harbor seals haul-out on the mud flats located on 
either side of the bridge. During a previous project at this site 
involving pile driving, harbor seals were observed to be present during 
construction and reportedly entered and exited the area without any 
visible signs of stress or undue harassment (MACTEC Engineering and 
Consulting 2003). Therefore, animals are likely tolerant or habituated 
to anthropogenic disturbance, including pile driving. Finally, breeding 
and pupping occur outside of the proposed work window; therefore, no 
disruption to reproductive behavior is anticipated. There is no 
anticipated effect on annual rates of recruitment or survival of the 
affected harbor seal population.
    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 mitigation and monitoring 
measures, NMFS determined that the Parsons Slough sill project will 
result in the incidental take of small numbers of marine mammals, by 
Level B harassment only, and that the total taking from the Parsons 
Slough project will have a negligible impact on the affected species or 
stocks.

Impact on Availability of Affected Species or Stock for Taking for 
Subsistence Uses

    There are no relevant subsistence uses of marine mammals implicated 
by this action. Endangered Species Act (ESA)
    No ESA-listed species under NMFS' jurisdiction are expected to be 
affected by these activities. Therefore, NMFS has determined that a 
section 7 consultation for issuance of the proposed IHA under the ESA 
is not required. The NOAA Restoration Center, Southwest Region, 
completed a formal consultation with the USFWS because the project is 
within the range of the southern sea otter, which is listed as 
threatened under the ESA. On October 6, 2010, the U.S. Fish and 
Wildlife Service issued a Biological Opinion and Incidental Take 
Statement to the NOAA Restoration Center, Southwest Regional pursuant 
to Section 7 of the ESA. The Biological Opinion concluded that impacts 
from the NOAA Restoration Center, Southwest Region's project would not 
jeopardize the continued existence of ESA-listed southern sea otters.

National Environmental Policy Act (NEPA)

    Pursuant to NEPA, the general impacts associated with the design 
and construction phases of the proposed action are described in the 
Community-Based Restoration Program (CRP) Programmatic Environmental 
Assessment (PEA) and the Supplemental Programmatic Environmental 
Assessment (SPEA), which were prepared by the NOAA Restoration Center, 
Southwest Region. The NOAA Restoration Center, Southwest Region, 
completed a Targeted Supplemental Environmental Assessment (TSEA) to 
include all project-specific impacts not described in the CRP PEA/SPEA. 
NMFS considered the TSEA to be adequate and adopted it on November 22, 
2010. On November 23, 2010, NMFS issued a Finding of No Significant 
Impact on the TSEA.

Authorization

    As a result of these determinations, NMFS has issued an IHA to the 
NOAA Restoration Center, Southwest Region, for the take of marine 
mammals incidental to the Parsons Slough project, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated.

    Dated: November 23, 2010.
P. Michael Payne,
Acting Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2010-30235 Filed 11-30-10; 8:45 am]
BILLING CODE 3510-22-P