Draft MMPA IHA_USCG Station Siuslaw_41624.pdf

U.S. Coast Guard Station Siuslaw River Project Draft Request for Marine Mammal Protection

Act Incidental Harassment Authorization

April 2024

Prepared for the U.S Coast Guard by

Tetra Tech, Inc.

1750 S Harbor Way, Suite 400 Portland, OR 97035

P 503.221.8636 F 503.227.1287 tetratech.com

Project # 100-WTR-T42147

Updated October 2023 by:

Campbell Environmental, LLC

28948 SW Meadows Loop P 503.680.8390 Wilsonville, OR 97070 campbellenviro.com

U.S Coast Guard Station Siuslaw Draft IHA

April 2024 i

CONTENTS

1.0 INTRODUCTION & DESCRIPTION OF ACTIVITIES

1.1Introduction 1.2Description of Activities

1.2.1 Onshore Infrastructure Improvements and Sitework

1.2.2 Shoreline Stabilization (Phase I)

1.2.3 Offshore Infrastructure Demolition and Replacement (Phase II)

1.2.4 Equipment and Methods

2.0 DATES, DURATION, AND SPECIFIED GEOGRAPHIC REGION

2.1Dates and Durations of Activities 2.2Geographic Region

3.0 SPECIES AND NUMBERS OF MARINE MAMMALS

4.0 AFFECTED SPECIES STATUS AND DISTRIBUTION

4.1California Sea Lions

4.1.1 General Biology

4.1.2 Distribution and Range

4.1.3 Status, Population Trends, and Threats

4.2Steller Sea Lions

4.2.1 General Biology

4.2.2 Distribution and Range

4.2.3 Status, Population Trends, and Threats

4.3Pacific Harbor Seals

4.3.1 General Biology

4.3.2 Distribution and Range

4.3.3 Status, Population Trends, and Threats

4.4Harbor Porpoise

4.4.1 General Biology

4.4.2 Distribution and Range

4.4.3 Status, Population Trends, and Threats

4.5Summary

5.0 TYPE OF INCIDENTAL TAKE AUTHORIZATION REQUESTED

5.1In-Air Noise 5.2Underwater Noise

6.0 TAKE ESTIMATES FOR MARINE MAMMALS

6.1In-Air Acoustic Results 6.2Underwater Acoustic Results

April 2024 ii

6.3Impact Summary

6.3.1 Species Density

6.3.2 Incidental Take Estimates

7.0 ANTICIPATED IMPACT OF THE ACTIVITY

8.0 ANTICIPATED IMPACTS ON SUBSISTENCE USES

9.0 ANTICIPATED IMPACTS ON HABITAT

10.0 ANTICIPATED EFFECTS OF HABITAT IMPACTS ON MARINE MAMMALS

11.0 MITIGATION MEASURES TO PROTECT MARINE MAMMALS AND THEIR HABITAT

11.1 General Construction Measures

11.2 Pile removal and Installation BMPs

11.2.1 Water Quality

11.2.2 Noise and Vibration

11.2.3 Hazardous Materials

11.2.4 Habitat Disturbance or Alteration

11.2.5 Collision

12.0 MONITORING AND REPORTING

13.0 SUGGESTED MEANS OF COORDINATION

14.0 REFERENCES

LIST OF FIGURES

Figure 1-1. Project Site Map

Figure 1-2. Preliminary design of a typical section for the tubular steel interlocking pile wall

Figure 2-1. Project Vicinity

Figure 6-1. In-Air Acoustic Threshold Limits for Construction

Figure 6-2. In-Air Acoustic Threshold Limits for Pile Removal

Figure 6-3. In-Air Acoustic Threshold Limits for Pile Installation

Figure 6-4. Underwater Acoustic Threshold Limits for Impact Pile Driving

Figure 6-5. Underwater Acoustic Threshold Distances Impact Pile Driving

Figure 6-6. Underwater Acoustic Threshold Distances for Impact Pile Driving

Figure 6-7. Underwater Acoustic Threshold Distances Vibratory Pile Installation

Figure 6-8. Underwater Acoustic Threshold Distances Vibratory Pile Removal

Figure 6-9. Underwater Acoustic Threshold Distances Vibratory Pile Removal

Figure 6-10. Level A and Level B Zones and Potential PSO Location

April 2024 iii

LIST OF TABLES

Table 1-1. Summary of Piles and Estimated Installation Requirements

Table 2-1. Project Location Attributes

Table 3-1. Summary of Marine Mammals Observed in the Project Vicinity

Table 5-1. Construction Equipment Source Levels, Lmax dBA

Table 5-2. Underwater Acoustic Threshold Levels for Marine Mammals

Table 5-3. Underwater Acoustic Modeling Scenarios

Table 6-1. In-air Acoustic Modeling Results - Distances of Maximum Disturbance, dB

Table 6-2. Marine Mammal PTS Onset Criteria Threshold Distances (meters) for Impact Pile Driving 21

Table 6-3. Marine Mammal Injury Onset Criteria Threshold Distances (meters) for Vibratory Hammer Pile Installation and Removal

Table 6-4. Marine Mammals Behavioral Response Criteria Threshold Distances for Impact and Vibratory Pile Driving

Table 6-5. Summary of Density Estimates used in Take Calculations

Table 6-6. Summary of Level A Exclusion Areas and Level B Harassment Zones for each of the Scenarios

Table 6-7. Summary of Most Conservative Level A Exclusion Zones and Level B Harassment Zones for Pile Installation

Table 6-8. Summary of Most Conservative Level A Exclusion Zones and Level B Harassment Zones for Pile Removal

Table 6-9. Summary of Take Estimates for Marine Mammals

APPENDICES

A: Draft Project Drawings

B: Acoustic Analysis

April 2024 iv

LIST OF ACRONYMS

BMPs Best Management Practices CFR Code of Federal Regulations cy Cubic Yard dB Decibels dBA

DPS

Weighted decibels Distinct Population Segment

ESA Endangered Species Act FR Federal Register Ft

GRLWEAP

HAZMAT

HF

HMT

IHA

Feet GRL Engineers Inc. Wave Equation Analysis of Pile Driving Hazardous Materials High frequency Highest Measured Tide Incidental Harassment Authorization

IWWW

LF

LID

Lmax

In-water work window Low frequency Low Impact Development Maximum Sound Pressure Level

Lpk Peak Sound Pressure Level M

MF

MHT

MLB

MLLW

Meter Mid-frequency Mean High Tide Motor Lifeboat Mean Lower Low Water

MMPA

μPa

M/SI

Marine Mammal Protection Act Micropascal Mortality/Serious Injury

Nmin

NOAA

Minimum Population Estimate National Oceanic and Atmospheric Administration

NOAA Fisheries NOAA National Marine Fisheries Service ODFW Oregon Department of Fish and Wildlife OHWM Ordinary High-Water Mark

PBR Potential Biological Removal

April 2024 v

PPE

PGIS

PSO

Personal protective equipment Pollution Generating Impervious Surface Protected Species Observer

PTS Permanent Threshold Shift

RM

RMS

SAR

River Mile Root mean square Stock Assessment Report

SEL

SELcum

Sound Exposure Level Accumulated Sound Energy

SF

SPCC

SPL

Square Foot Spill Prevention, Containment, and Countermeasure Sound Pressure Level

SWPPP

TESC

Stormwater Pollution Prevention Plan Temporary Erosion and Sediment Control

TTS Temporary Threshold Shift USACE United States Army Corps of Engineers

USCG United States Coast Guard ZOI Zone of Influence

April 2024 1

1.0 INTRODUCTION & DESCRIPTION OF ACTIVITIES

1.1 INTRODUCTION

Pursuant to the Marine Mammal Protection Act (MMPA) Section 101(a)(5)(D), this document constitutes a request for an Incidental Harassment Authorization (IHA) for the take of marine mammals incidental to a U.S. Coast Guard (USCG) project to correct shoreline erosion and replace the covered mooring and appurtenant offshore structures at USCG Station Siuslaw River (Station) in Florence, Oregon. This application includes the potential effects of the project’s proposed activities on marine mammals and their habitat in the region, as well as mitigation measures and monitoring protocols to minimize those effects. This IHA is submitted to ensure the project does not result in takes that exceed the numbers and levels of those requested.

This application is intended to cover in-air construction and in-water demolition and construction activities that may result in takes of marine mammals for one year beginning on November 1, 2025.

Project activities are anticipated to continue through October 31, 2026; therefore, the project is divided into two phases for take authorization purposes. All activities that may result in the take of marine mammals are discussed together in this application.

1.2 DESCRIPTION OF ACTIVITIES

Both onshore and offshore work will occur including site preparation, demolition, shoreline stabilization measures, pile removal and installation, and overwater construction. The USCG proposes to install an interlocking steel pile wall along the length of the Station property waterfront with the top of the wall above the highest measured tide (HMT) elevation to correct shoreline erosion while minimizing project impacts below the HMT elevation. The proposed offshore infrastructure will be constructed in the same location as the existing covered mooring with a slightly larger footprint and engineered to resist weathering and future riverbed scour.

The project footprint, or the limits of direct construction-related ground disturbance, will include onshore and offshore areas of disturbance within the project area depicted in Figure 1-1. Onshore disturbance, or disturbance above the HMT elevation, will include upper slope stabilization measures including a new sheet pile wall and a retaining wall, site preparation, demolition, excavation and fill in uplands for stormwater infrastructure improvements, stockpile areas, and fencing to accommodate slope stabilization measures. Offshore disturbance, or disturbance below the HMT elevation, will include removal of up to 71 existing timber and steel H-piles, the boathouse superstructure and pier access bridge, and fixed debris screen supports; and installation of up to 79 replacement steel piles for replacement of the boathouse, access pier bridge, and fixed debris screen.

In addition to construction activities associated with the shoreline correction and boathouse replacement, the federal action includes temporary use of mooring and parking facilities found at the downtown waterfront of Florence. Use of these facilities would not require modification of navigation or mooring facilities and will not result in additional in-water disturbance other than minor noise from daily ingress or egress of USCG motor lifeboats (MLBs). Due to the low impact of this component of the proposed action, it is not discussed further in this document.

April 2024 2

Phasing

Construction is anticipated to occur in two phases over an approximate two-year duration, depending on environmental and regulatory requirements, final plans and specifications, and options awarded to the construction contractor. Activities occurring during each phase are described in Section 2.1.

April 2024 3

Figure 1-1. Project Site Map

April 2024 4

1.2.1 Onshore Infrastructure Improvements and Sitework

The existing, upland storm drain system consists of storm drain pipes and structures, and a below-surface horizontal drain array that collects at a triangular soil nail wall catchment area. The collected stormwater and groundwater are combined to discharge near the top of the slope through a controlled outfall protected with rip rap.

Stormwater improvements will include minor modifications including some Low Impact Development (LID) storm system features that will reduce erosion and sedimentation loss at the project site. No additional impervious surface area will be added as part of the project. The concept is to adjust the existing storm drainage system and convey the stormwater to a single outfall and discharge beyond the new sheet pile wall onto an energy dissipater. Existing drainage structures will be retrofitted with manufactured treatments such as filter inserts for water quality treatment and LID best management practices (BMPs) will be incorporated where feasible to meet the City of Florence stormwater design standards. BMPs included in final designs may include but would not be limited to bioswales with engineered soils/gravel and a subsurface drain to emphasize filtration, storage, and evaporation and transpiration before runoff is conveyed to the outfall. The project will likely result in a slight, net decrease in existing impervious surfaces. The project will include the following onshore stormwater infrastructure improvements:

• Addition of drainage swales with gravel trench drains to redirect runoff from the embankment and to slow down the surface flow and collect groundwater flow. The stormwater in the swale will discharge into the triangular soil nail wall catchment area prior to outfalling through a controlled outlet structure.

• Addition of a trench drain to collect stormwater runoff currently flowing down the pier access driveway and over the embankment. The trench drain will redirect the runoff into a drainage structure which will release runoff at a controlled rate and prevent stormwater discharge onto the steep slope.

• Retrofit or replacement of existing catch basins with water quality filtration unit(s) to treat runoff from impervious surfaces considered to be a significant source of pollutants in stormwater runoff, or pollution generating impervious surfaces (PGIS), before being conveyed and discharged from an outfall at the riprap layer. Filtration units specifically designed to capture specific pollutants such as zinc, copper, and sediments will be installed.

• Reconstruction of drainage outlet structure including water quality filtration inserts.

• A grassy swale underlain by a gravel trench will be installed along the top of the steep slope to collect lawn area surface sheet flows and shallow subsurface flows and convey them to the outfall onsite.

• A surface-mounted storm outfall pipe anchored to the embankment slope will replace the existing outfall. The new outfall will discharge beyond the new sheet pile wall to an energy dissipater to prevent embankment erosion at the upper elevation.

• Minor asphalt pavement repairs in the parking lot where the embankment failure occurred.

• Shoreline stabilization including pile walls, a retaining wall and embankment reestablishment with native vegetation as described in the following section.

1.2.2 Shoreline Stabilization (Phase I)

Shoreline stabilization will be accomplished through construction of an upland, steel interlocking pile wall, with the above-grade portion of the wall above the 50-year calculated extreme tide level (Figure 1-2). The top of the wall will be approximately 3.5 meters ( 12 feet) above MHHW. It will run

April 2024 5 approximately 111 meters (400 feet) along the top of bank from approximately the north property line to the south property line, with approximately 30 foot returns inland and upslope at either end. The wall will implement a long-term solution by adding a rigid structure of steel sheet or pipe piles, with grouted soil tie-back anchors located near the top of the wall, that would retain upper and lower slope sands and mitigate negative scour effects on the soils landward of the wall. A drainage element (e.g., weep hole) through the wall at the elevation where the paleosol layer contacts the upper dune sands will facilitate a free-draining retention system (e.g., a nonwoven geotextile or an open-graded aggregate filter) to relieve groundwater flow and prevent loss of dune sand material.

Figure 1-2. Preliminary design of a typical section for the tubular steel interlocking pile wall

Sheet or pipe pile installation would be a combination of auger predrilling and/or hydraulic press-in installation, as opposed to driven or vibratory installation approaches, which were determined to be less desirable as primary methods of installation, considering the hardness of the Lower Dune Sand layer and the potential for negative impacts to the marginally unstable slope. The wall is planned to be installed above HMT, just upslope of the existing riprap installed in 2016, which will be disturbed as little as possible. It should be noted that scour forces in the river at this location are significant and have changed the depth of the riverbed to a great extent in this location over the last sixty years. It is entirely possible that future scour will remove more bank material and remove or relocate the riprap and leave a more significant wall height exposed on the river side. The wall will be structurally designed for this potential future retained height.

Upslope of the proposed pile wall, protection against seepage-induced erosion and washout of lower sands will be provided to prevent undermining and erosion of the silt layer. The sand slope above the wall will be graded to maximum slope of 2H:1V and stabilized and protected through application of a geocell cellular confinement geotextile, nonwoven geotextile filtration system with granular stone embankment material, biotic soil media planted with native vegetation or a combination thereof.

Several surface swales with gravel trench drains will be added to divert surface runoff from sheet-flowing down the embankment and channeling them to the existing underground storm drain system.

The existing outfall at the downstream end of the stormwater system will be extended with a pipe that will be placed at-grade with cutoff concrete collars and outfall beyond the new wall.

April 2024 6

A second, smaller wall is proposed near the crest of the slope at the edge of the existing parking lot in the southwest corner of the property. This wall will be a cantilevered design, with the pile embedment taking into consideration the regraded slope of 2H:1V.

1.2.3 Offshore Infrastructure Demolition and Replacement (Phase II)

The Station’s existing covered mooring, bridge, and debris boom will be demolished, and all piles will be removed. Piles supporting the boathouse to be removed include the original timber vertical piles and timber batter piles installed in 1969, and steel H-piles installed in 2008. Demolition debris and materials will be transported to a permitted landfill and/or recycling facility. In total, approximately 71 piles will be removed by vibratory hammer. A conservative estimate for vibratory extraction is 15 minutes per pile. If any timber piles break during removal, the remaining portion of the broken piles will be cut 0.6 meters (two feet) below the mud line. Removed piles will be disposed of in an upland location.

The following new facilities will be constructed: a 4,730 square foot (SF), two-bay covered mooring, including an interior floating dock for two 47’ MLBs, a mezzanine and deck space for engineering shop, storage, personal protection equipment (PPE) and hazardous materials (HAZMAT); a 1,220 SF pedestrian bridge, including a small marine diesel fueling platform; a 520 SF exterior floating dock; and a vertical debris screen. Total overwater structures will cover approximately 6,500 SF. It is estimated that up to 79 replacement steel piles will be necessary to reconstruct the boathouse, floating docks, bridge, and debris screen. The new piles will be 16-inch to 20-inch steel pipe piles filled with concrete, and/or 14-inch steel H-Piles which will be installed by vibratory driving and driven to the final tip elevation by impact strikes after the initial vibratory set. The exact sizes and quantities of pipe piles used will be determined through the remaining design iterations. The new pier access and debris screen will be constructed in approximately the same footprint as the existing structures to minimize riverbed soil disturbance and shadowing from overwater structures. The new covered mooring footprint will be approximately 1,800 SF larger than the existing structure. The southeast corner will be placed in the same location, but the west end of the structure will extend 8.3 meters (30 feet) further out into the Siuslaw River to accommodate the two 47 ft MLBs. The existing covered mooring width is insufficient for mooring the two 47 ft MLBs. This will result in additional shadowing compared to existing conditions.

To mitigate for the additional pilings (approximately eight), and expansion of the covered mooring (approximately 1,800 SF), the Applicant is proposing to purchase 2,000 SF of estuarine credits from the Wilbur Island Mitigation Bank and is currently coordinating with the Oregon Department of State lands on the credit approval and purchase. Estuarine wetlands have historically been degraded and lost in the Siuslaw watershed.

1.2.4 Equipment and Methods

During Phase I, it is anticipated that the installation of the upland pile wall would be from a barge or similar floating work platform which would also serve as the primary staging area. Typical equipment for this work would include a drill or hydraulic rig (or both), an appropriately sized crawler crane or tracked hydraulic excavator (or both) for mounting and operation of the drill or hydraulic rigs operated from a spud barge, and a support and materials barge. A small support boat and barge tug would be required periodically for positioning equipment or materials. To facilitate construction of the pile wall a bench will be needed on the upper slope (above HMT) for access or another similar means to construct the wall and install the tie-backs. The upper slope will be fully restored including invasive removal and native revegetation with a contractor-required establishment and maintenance period.

April 2024 7

During Phase II, upland site and stormwater infrastructure work will require a staging area designated within the Station’s property for heavy equipment and materials. A temporary stockpile area or areas will also be designated. Temporary erosion and sediment control BMPs, including outlet protection, inlet protection, biofilter bags, stabilized construction entrances, sediment fencing, and straw wattles as appropriate for site conditions will be installed prior to ground disturbance. Typical equipment for this work would include one or more appropriately sized tracked hydraulic excavators, wheel loader, track loader, on-road dump truck(s), water pumps, pavement sawing equipment, compacting equipment, paving machinery, and common landscaping equipment. Excavated materials will either be stockpiled for reuse or removed from the site to a permitted landfill as per the final plans and specifications.

Disturbed natural area grades and vegetation will be restored upon completion of stormwater infrastructure upgrades and sitework.

Piling removal is expected to be accomplished with a vibratory pile driver/extractor mounted to a crawler crane operated from an appropriately sized spud barge. Removed piles will be staged on a second demolition debris barge for transportation. All pier pilings and timbers to be demolished are either steel, or wood creosote or salt treated. The contractor will be required to ensure that these timbers are handled and disposed of in accordance with applicable local, state, and federal regulations.

The contractor will also be required to perform all required sampling and analysis and provide any required shipping and disposal paperwork. In addition, if any unidentified or unexpected hazardous materials are discovered during demolition work, the contractor will be required to immediately notify the USCG prior to commencing any further cleanup of the discovered materials.

Construction of the offshore infrastructure would be accomplished from a barge, or multiple barges, using similar equipment as described above for installation of the pile wall. It is assumed that up to three piles will be driven each 8-hour workday. The actual driving time for each pile could be as much as approximately one hour but is anticipated to be less. Thus, an estimated 28 total days of pile driving (not all consecutive) and 20 days of non-consecutive pile removal will occur over the duration of the project. A full pile driving analysis will be completed to further refine and guide pile installation and the appropriate BMPs for pile installation. Smaller work vessels and platforms will be utilized to construct the covered mooring superstructure.

Exact equipment requirements and construction means and methods for both phases will be determined through ongoing studies, surveys, and the design-build contractor’s design process using the final engineering designs, specifications, and estimates.

Table 1-1. Summary of Piles and Estimated Installation Requirements

Pile Diameter x thickness (inches)1 Supporting/Guiding

Total Number Driver/Hammer

Estimated Strikes/Pile2

Estimated Minutes/Pile2

Estimated Blows/Minute2

20 x 0.625 Covered Mooring (Boathouse); Floating

Docks; Bridge

49 D46 975 24 40

16 x 0.5 Boathouse; Debris Screen

30 D46 975 24 40

1 All pile thicknesses provided are estimates as the selected design-build contractor will complete the actual design.

2 Based on the GRL Engineers, Inc. Wave Equation Analysis of Pile Driving (GRLWEAP) model. The GRLWEAP model was used to calculate the estimated strikes, estimated minutes, and estimated blows. The GRLWEAP model was not used for sound source level or acoustic propagation modeling (see Appendix A for further details on acoustic modeling) 3 Piles would be driven at a mudline elevation above +10.5 feet NAVD88

April 2024 8

2.0 DATES, DURATION, AND SPECIFIED GEOGRAPHIC REGION

2.1 DATES AND DURATIONS OF ACTIVITIES

The project is anticipated to occur over an approximate two-year period, depending on environmental and regulatory requirements, final plans and specifications, and options awarded to the design-bid-build contractor. It is also noteworthy that interlocking pipe piles are a specialized product with limited market sources which could in turn affect the schedule. The USCG would complete work to occur below the HMT elevation during the Oregon Department of Fish and Wildlife (ODFW)-preferred in-water work window (IWWW) from November 1 to February 15. Over-water construction actions, or those action which will be performed waterward of HMT but above the elevation of HMT, may be performed outside of the IWWW subject to contractor means and methods complying with permitting and MMPA consultation conditions.

Phase I: Based on preliminary project acquisition planning, Phase I construction is likely to commence in the 3rd quarter of 2024. Initial steps include the mobilization of materials and equipment to construct the steel interlocking pile wall and initiate shoreline stabilization. There will be no in-water work during this phase.

Phase II: Mobilization, materials and equipment staging, and the demolition and construction of the offshore infrastructure (Phase II) would follow with in-water work projected to occur from November 1, 2025 through February 15, 2026. Remaining overwater work to construct the covered mooring superstructure may occur later in the second year during more favorable weather conditions.

2.2 GEOGRAPHIC REGION

The Station is located on the river right (east) bank of the Siuslaw River at river mile (RM) 1.5, approximately three miles north-northwest of the downtown waterfront of the City of Florence in Lane County, Oregon (Figure 2-1). Vegetated dunes in the Oregon Dunes National Recreation Area, protected by a series of four rock groin structures, is located on the opposite bank of the Siuslaw River from the Station. This application considers the effects of noise disturbance that may occur during both onshore and offshore construction activities at the USCG Station Siuslaw River property, and a temporary mooring area proposed for use during construction (Figure 2-1).

April 2024 9

Figure 2-1. Project Vicinity

April 2024 10

Table 2-1. Project Location Attributes

Attribute Description Township, Range, Section T18S, R12W, S15 Latitude, Longitude (decimal degrees) 44.002417, -124.122336 Nearest City Florence, OR County Lane 12-digit Hydrologic Unit Code Bernhardt Creek-Siuslaw River - 171002060804 Siuslaw River Mile 1.5

3.0 SPECIES AND NUMBERS OF MARINE MAMMALS

Marine mammals that have the highest potential to occur near the project area include the California sea lion (Zalophus californianus), Steller sea lion (Eumetopias jubatus), Pacific harbor seal (Phoca vitulina), and harbor porpoise (Phocoena phocoena) (ODFW 2020). These species frequent the lower Columbia River and adjacent nearshore marine areas (Carretta et al. 2022). A summary of each species’ abundance (minimum population estimate; NMIN), special status listings, potential biological removal (PBR), annual mortality and serious injury (Annual M/SI) totals, and year of last stock assessment report (SAR) update is provided in Table 3-1.

Table 3-1. Summary of Marine Mammals Observed in the Project Vicinity

Common name Stock

ESA/MMPA

Status

Stock Abundance

(NMIN) PBR Annual M/SI SAR Last Revised

California sea lion/a

United States Not listed / Protected

233,515 14,011 ≥321 2019

Steller sea lion/b

Eastern U.S. Not listed / Protected

43,201 2,592 112 2019

Pacific harbor seal/a

Oregon/Washington Coast Not listed / Protected

24,732/c undetermined/c 10.6 2014

Harbor porpoise/a

Northern OR/WA Not listed / Protected

15,123 151 ≥3 2014

Notes: /a Caretta et al. 2022, /b Muto et al. 2021, /c population estimate, no current information on abundance is available to obtain a minimum population estimate or PBR for the Oregon/Washington Coast stock of harbor seals.

California sea lions, Steller sea lions, and harbor seals are the species most likely to occur within the immediate project vicinity. The nearest haul-out for pinniped species is for harbor seals and is across the river from the Station, approximately 150 meters (500 feet(ft)) away. California and Steller sea lions are predominantly present seasonally during the winter months numbering in the hundreds, and harbor seals are present year-round numbering in the thousands (NOAA 2023a; NOAA 2023b). Harbor porpoises may also transit the area year-round, though in very small numbers as compared to California sea lions, Steller sea lions, or harbor seals. Additional information regarding species abundance, range, status, and management is provided in Section 4.

Takes incidental to construction activities at the Station are anticipated for each of these species depending on the type of activity and distance from sound sources. Types and estimates of anticipated incidental takes for each species are described in greater detail in Sections 5 and 6.

April 2024 11

Other marine mammal species considered for the project area include killer whales (Orcinus orca) from the Southern Resident killer whale distinct population segment (DPS) ecotype. This species is commonly observed along the Oregon coast at different times of the year. Killer whales occur in the Siuslaw river incidentally and have been opportunistically reported near and within the Siuslaw River mouth (Burtt 2022). While there have been occasional sightings in the Siuslaw River near its mouth at certain times of the year, killer whales are more likely to be found outside of the river mouth and further offshore. For these reasons, takes of these species during project activities are not anticipated, and this application does not further evaluate impacts to these cetacean species.

4.0 AFFECTED SPECIES STATUS AND DISTRIBUTION

The following sections provide additional information on the species that have the greatest potential to be affected by project activities.

4.1 CALIFORNIA SEA LIONS

4.1.1 General Biology

California sea lions have broad front flippers, visible ear flaps, and long, narrow snouts. Adult males are typically larger and darker brown than females, which are smaller and can be blonder to more tan in color. They are members of the “eared seal” family, Otariidae, and they are among the most recognized of the pinniped species. Their breeding season lasts from May to August, while most pups are born from May through July. Pups are weaned at 10 months old, reaching their sexual maturity at four to five years old, and they have a lifespan of 20 to 30 years. They feed on squid, anchovies, mackerel, rockfish, and sardines and their movement often follows food supply patterns (NOAA 2023a). Male California sea lions bark to communicate with other males and females and are typically social animals (NOAA 2023a).

4.1.2 Distribution and Range

California sea lions are distributed along the west coast of North America from central Mexico to southeast Alaska. NOAA Fisheries divides the California sea lion population into three stocks based on rookeries and the international border. The U.S. stock waters range from the U.S. border with Mexico to the border with Canada. California sea lions do not breed in Oregon; their primary breeding areas range from the Channel Islands in southern California to central Mexico. Males migrate in the winter to feeding areas along the Oregon coast, while most females typically remain in southern waters closer to the rookeries. Males then return south for the breeding season from late June to early August, so their population in Oregon is highest during the winter months from September through May. California sea lions haul out on sandy beaches and rocky coves in addition to man-made marine structures such as docks, jetties, and buoys (NOAA 2023a).

California sea lions, particularly adult males (DeRango et al. 2019), are most commonly present in Florence in late summer through the fall during the post breeding season, though also may occur in smaller numbers in winter and early spring (Wright et al. 2010). They may be transiting through the project area during the IWWW from November through February during their migrations. They have also been known to haul-out along jetties and the sandy shoreline opposite the Station (ODFW 2022).

April 2024 12

4.1.3 Status, Population Trends, and Threats

California sea lions are not listed under the Endangered Species Act (ESA) and the U.S. stock is not considered strategic or depleted under the MMPA (Carretta et al. 2022). The minimum population estimate is 233,515 animals, with an estimated net productivity rate of 7% each year, but NOAA Fisheries notes that the population is capable of faster growth rates (Carretta et al. 2022). Threats to this species include incidental catch and entanglement in fishing gear, biotoxins resulting from harmful algal blooms, and human-caused injuries and mortalities, particularly as California sea lions are sometimes viewed as a nuisance by commercial fishermen (NOAA 2023a). Exposure to anthropogenic sound has also been found to incite a variety of behavioral responses in California sea lions (Carretta et

al. 2022).

4.2 STELLER SEA LIONS

4.2.1 General Biology

The Steller sea lion is the largest member of the “eared seal” family, Otariidae. Steller sea lions are light blonde to reddish brown in appearance and slightly darker on the chest and abdomen. Males can grow to approximately nine feet and 2,000 pounds, while females grow to approximately six feet and 700 pounds (ODFW 2020). They have a lifespan of 20-30 years, and are opportunistic predators, foraging and feeding primarily at night on a wide variety of fishes such as herring, mackerel, rockfish, and salmon, bivalves, squid, octopus, and gastropods (NOAA 2023b). Their diet may vary seasonally depending on the abundance and distribution of prey. They may disperse and range far distances to find prey but are not known to migrate.

Steller sea lions breed in off the coast of central and southern Oregon during the months of June and July, with a gestation period of about 11.5 months. Males reach sexual maturity between three and eight years of age and can live to be 20 years old, while females reproduce for the first time at four to six years and can live to be 30 (NOAA 2023b).

4.2.2 Distribution and Range

The Steller sea lion range extends along the Pacific Rim, from northern Japan to central California.

Those inhabiting US waters have been divided into two DPSs: the Western US DPS and the Eastern US DPS (Muto et al. 2021). The population known to occur near the Port of Florence is the Eastern

DPS (ODFW 2020).

Steller sea lions haul out on offshore rocks and islands along the Oregon coast. Most of these haul-out sites are part of the Oregon National Wildlife Refuge and are closed to the public, including large breeding areas at Three Arch Rocks (Oceanside), Orford Reef (Port Orford), and Rogue Reef (Gold Beach) (ODFW 2020). The Oregon Department of Fisheries and Wildlife Marine Mammal Program Atlas of Steller sea lion haul-out sites lists 11 different haul-out locations, with only one, the Sea Lion Caves, located close to the project area (ODFW 2023). The Sea Lion Caves are a privately owned wildlife preserve located 11 miles north of Florence and a well-known, year-round Steller sea lion haul-out area. Hundreds of sea lions are reported to inhabit the caves during winter months, moving to the rookery areas on the rock ledges in front of the caves during spring and throughout summer. The Steller Sea Lion Research Initiative conducted a large-scale study on the seasonal haul-out abundance

April 2024 13 patterns in Oregon and northern California. Authors pointed out the importance of Sea Lion Caves as a wintertime haul-out site and nursery during winter and spring and speculate that they caves may be an important site due to protection from weather and ocean conditions as well as availability of prey at nearby Heceta Bank (Scordino 2006).

It is likely Steller sea lions could be present near or in the project vicinity during their peak abundance in the winter, though fall occurrences are possible, with their presence less likely during spring and summer months.

4.2.3 Status, Population Trends, and Threats

Steller sea lions are not listed under the ESA, nor are they considered depleted or strategic under the MMPA. The current minimum population estimate for the Eastern DPS in U.S. waters is 43,201 individuals (Muto et al. 2021). The Eastern DPS population is now considered stable and slightly increasing in size (ODFW 2020). NOAA Fisheries estimated the eastern stock increased at a rate of 4.25% per year between 1987 and 2017, driven by growth in pup counts in all regions. Because of this steady population growth, the Eastern DPS was delisted under the ESA in 2013 and is not considered depleted or strategic under the MMPA (Muto et al. 2021, NOAA 2023b).

Threats to Steller sea lions include vessel strikes, contaminants/pollutants, habitat degradation, illegal hunting or shooting, and interactions with fisheries including entanglement and changes in availability of prey. Critical habitat associated with breeding and haul-out sites in Alaska, California, and Oregon was designated on August 27, 1993 (58 FR 45269) but does not overlap the project impact area.

4.3 PACIFIC HARBOR SEALS

4.3.1 General Biology

The Pacific harbor seal is the most widespread and abundant resident pinniped in Oregon. Their bodies are gray with light and dark speckling and adults can be up to six feet in length and 300 pounds in weight. The Pacific harbor seals are part of the "true seal" family, Phocidae, lack external ear flaps, and have short forelimbs (ODFW 2020). They are fast, agile swimmers, and as social animals, they form groups of several hundred individuals onshore. They eat mostly fish, shellfish, and crustaceans, and are considered non-migratory but have been documented traveling up to 450 miles seasonally to forage or give birth (NOAA 2023c).

Harbor seals mate at sea generally in the warmer months, and pupping season is from mid-April to July (NOAA 2023c). Males reach sexual maturity at five to six years of age, females sexually mature at two to five years, and they have a lifespan of about 25-30 years. Females can give birth to one pup each year, which weigh about 10 pounds and can swim at birth. Females leave their pups at haul-outs or along sandy beaches while searching for food. In Oregon, pups are born in late March through April

(ODFW 2020).

4.3.2 Distribution and Range

Five stocks of harbor seals are found along the west coast of North America from Baja California, Mexico to the Bering Sea. Individuals found along the Oregon coast belong to the Oregon/Washington

April 2024 14

Coastal stock. In 2014, the population of Pacific harbor seals along the Oregon coast was estimated at 11,565 individuals (Wright 2014). In 1999, it was estimated that the entire Oregon/Washington Coastal stock of Pacific harbor seals consisted of about 24,732 animals, no more recent estimates are available (Carretta et al. 2022).

Harbor seals haul-out at low tide on sand bars in most bays and estuaries along the Oregon coast, including at the mouth of the Siuslaw River near the project vicinity. Harbor seals tend to haul out in groups and females sometimes raise their pups in nurseries for protection from predators (ODFW 2020). The Oregon Department of Fisheries and Wildlife Marine Mammal Program harbor seal study map depicts haul-out sites for harbor seals in the mouth of the Siuslaw River on both the east and west bank (ODFW 2023b). Wilson (1993) described harbor seal haul out sites along the Southern Oregon Coast which include the Siuslaw River haul-out site, located on the eastern bank of the Siuslaw River, approximately 2 miles from the river mouth and 500 ft north of the Station. In the mid-1980s NOAA conducted a three-year study to assess the status of pinniped populations in Oregon and found in the Siuslaw River that harbor seal numbers peak during winter, suggesting that the river may be important winter feeding area (Brown et al. 1988). In addition, pupping was recorded in the Siuslaw River during May, however in small numbers when compared to the other known pupping locations.

It is likely that harbor seals would occur throughout the project duration, including during the winter months.

4.3.3 Status, Population Trends, and Threats

The Oregon/Washington stock of Pacific harbor seals is not listed under the ESA, nor are they considered depleted or strategic under the MMPA. The most recent estimate for the population growth rate of the northern Oregon coast stock of harbor seals was approximately 10.1 percent annually (Caretta et al. 2022). Threats to this species include incidental capture in fishing gear, weirs, vessel strikes, pollutants/contaminants, and harassment by humans while hauled-out on land (NOAA 2023c).

4.4 HARBOR PORPOISE

4.4.1 General Biology

Harbor porpoise are dark gray to black with lighter undersides and are the smallest of the Northern Pacific cetaceans, growing up to five feet and weighing up to 165 pounds. They prefer estuaries, bays, nearshore waters typically less than 650 feet deep (ODFW 2022). They transit near the surface of the water, coming up to breathe about every 30 seconds, and forage small fish such as sardines and herring. Harbor porpoises are shy animals and typically avoid boats and wakes unlike other porpoise species. Mating most often occurs in the summer and most births occur from May to July following a ten- to eleven-month gestation period (NOAA 2023d).

4.4.2 Distribution and Range

The Harbor porpoise is found throughout the temperate coastal waters of the Northern Hemisphere.

Seasonal movement of harbor porpoises appears to be tied to prey availability and ice-free waters.

(NOAA 2023d). In general, harbor porpoises are found in waters < 650 ft in depth (Holdman et al.

2019).

April 2024 15

Harbor porpoises along the Oregon coast are considered to be composed of two stocks, a northern and southern population with the separation near Lincoln City. Individuals near the project vicinity are part of the Northern Oregon/Washington coast stock of harbor, which includes animals from Lincoln City, Oregon to Cape Flattery, Washington. The Northern Oregon/Washington Coast stock of harbor porpoises consists of about 21,487 individuals as of 2013 with a minimum population estimate of 15,123 porpoises (Carretta et al. 2022). An acoustic monitoring program deployed recording devices at locations on a reef and offshore of the central Oregon coast, approximately 2.5 miles (reef) and 7.5 miles (offshore) southwest of the Yaquina River inlet for a six-month period from May to October 2014.

Harbor porpoises were detected on 96% and 93% of the total monitored days at the reef and offshore site respectively, with peak detections during June and July (Holdman et al. 2019). Harbor porpoises are considered likely to occur in small numbers in the project area.

4.4.3 Status, Population Trends, and Threats

Harbor porpoises are not listed under the ESA, nor are they considered depleted or strategic under the MMPA. The primary threats to harbor porpoises are entanglement, pollution, and ocean noise (NOAA 2023d). They are preyed upon by killer whales in the Pacific Northwest (ODFW 2022). Harbor porpoises may transit through the project area throughout the proposed construction activities.

4.5 SUMMARY

California sea lions, Steller sea lions, Pacific harbor seals, and harbor porpoises are the marine mammals with the highest potential to be present within the project vicinity during construction activities. None of these marine mammals are ESA-listed as threatened or endangered or considered depleted or strategic under the MMPA. Three of the marine mammals listed (Steller sea lions, California sea lions, and Pacific harbor seals) have documented haul-out locations or breeding areas within the vicinity of the project area. The harbor seal is closest with haul outs 150 m (500 ft) away. All three of these species may be present to rest, forage, or transit the area during the construction period. It is possible that all four species may be impacted by noise generated during in-water pile driving from November 1 to February 29, as well as during demolition activities and over-water construction during the rest of the application request period. Other than exposure to underwater and airborne sounds, they are not anticipated to be impacted in any other way during the project.

April 2024 16

5.0 TYPE OF INCIDENTAL TAKE AUTHORIZATION REQUESTED

Under Section 101(a)(5)(D) of the MMPA, the USCG requests an IHA for the take of small numbers of marine mammals, by both Level A and Level B harassment, incidental to pile driving and demolition activities related to the proposed project. Pile driving and demolition are expected to produce sound levels that exceed the acoustic tolerance thresholds of marine mammals that have the potential to occur within the project vicinity. The USCG requests two back-to-back IHAs for incidental take of marine mammals during construction activities as described in this application for two years commencing November 1, 2024 (or the issuance date, whichever is later).

The MMPA (50 CFR 216.3) defines harassment as any act of pursuit, torment, or annoyance that:

1. has the potential to injure a marine mammal or marine mammal stock in the wild (Level A Harassment); or,

2. 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, but which does not have the potential to injure a marine mammal or marine mammal stock in the wild (Level B Harassment).

Level A harassment may result in injury or death, whereas Level B harassment causes only disturbance. Modeling of both in-air and underwater acoustic impacts was performed to analyze the effects of the proposed activities on marine and terrestrial biota. The full acoustic analysis, which includes detailed descriptions of the modeling calculations approach, modeled scenarios, and model input values, can be found in Appendix B.

5.1 IN-AIR NOISE

Current NOAA Fisheries’ practice regarding exposure of marine mammals to high-level in-air sounds, as a threshold for potential Level B harassment, is at or above 90 decibel (dB) root mean square (rms) re 20 μPa for harbor seals and at or above 100 rms dB re 20 μPa for all other pinniped species.

Construction equipment is measured using A-Weighted dB units known as dBA.

Table 5-1 presents the types of construction equipment anticipated for the project and corresponding maximum sound levels (Lmax) used for modeling potential in-air noise impacts.

April 2024 17

Table 5-1. Construction Equipment Source Levels, Lmax dBA

Phase Construction Equipment Quantity Equipment Noise Level at 50 ft., Lmax dBA Usage Factor

Mobilizing construction equipment, developing staging areas, barge landing areas, and construction of sheet or pipe pile installation through combination of auger predrilling and/or hydraulic press-in installation (Phase 1) Demolition (Phase 2)

Excavator 2 89 dB / 85 dBA 100

Hoe Ram 2 97 dB / 90 dBA 100

Front-end Loader 2 93 dB / 82 dBA 100

Bulldozer 2 89 dB / 85 dBA 100

Dump Truck 2

93 dB / 84 dBA

Piling Removal (Phase 2)

Vibratory Hammer 1 96 dB / 87 dBA 100

Excavator 1 89 dB / 85 dBA 100

Dump Truck 2 93 dB / 84 dBA 100

Crane 1 97 dB / 85 dBA 100

Grader 2 92 dB / 86 dBA 100

Construction of offshore infrastructure (Phase 2)

Vibratory Hammer 1 96 dB / 87 dBA 100

Impact Hammer 1 119 dB / 103 dBA 100

Excavator 1 89 dB / 85 dBA 100

Dump Truck 2 93 dB / 84 dBA 100

Crane 1 97 dB / 85 dBA 100

Sources: FHWA 2006 and DEFRA 2005

5.2 UNDERWATER NOISE

NOAA Fisheries provided guidance for assessing the impacts of anthropogenic sound on marine mammals under their regulatory jurisdiction, which includes whales, dolphins, porpoises, seals, and sea lions, which was updated in 2018 (NOAA 2018). The guidance specifically defines marine mammal hearing groups, develops auditory weighting functions, and identifies the received levels, or acoustic threshold levels, above which individual marine mammals are predicted to experience changes in their hearing sensitivity (permanent threshold shift [PTS] or temporary threshold shift [TTS]) for acute, incidental exposure to underwater sound. Under this guidance, any occurrence of PTS constitutes a Level A, or injury, take. The sound emitted by man-made sources may induce TTS or PTS in an animal in two ways: (1) peak sound pressure levels (LPK) may cause damage to the inner ear, and (2) the accumulated sound energy (SEL; sound exposure level) the animal is exposed to (accumulated sound energy; SELcum) over the entire duration of a discrete or repeated noise exposure has the potential to induce auditory damage if it exceeds the relevant threshold levels. For underwater noise, NOAA Fisheries defines the threshold level for Level B harassment at 160 dB sound pressure level (SPL)

April 2024 18

RMS for impulsive sound, averaged over the duration of the signal and at 120 dB SPL RMS for continuous (non-impulsive) sound.

Under the 2018 guidance, NOAA categorized marine mammals into five hearing groups to account for differences in hearing capabilities amongst species broken out into three categories of low-, medium-, and high- frequency hearing animals (LF, MF, and HF respectively). California sea lions and Steller sea lions fall within the otariid pinniped hearing group, harbor seals fall within the phocid hearing group, and harbor porpoise are part of the high-frequency (HF) cetacean hearing group.