23548 Federal Register / Vol. 77, No. 76 / Thursday, April 19, 2012 / Proposed Rules 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

50 CFR Part 217 

[Docket No. 110801455–2197–01] 

RIN 0648–BB16 

Taking and Importing Marine 

Mammals; Taking Marine Mammals 

Incidental to Columbia River Crossing 

Project, Washington and Oregon 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Proposed rule; request for 

comments. 

SUMMARY: NMFS has received a request 

from the Department of Transportation’s 

Federal Transit Authority (FTA) and 

Federal Highway Administration 

(FHWA), on behalf of the Columbia 

River Crossing project (CRC), for 

authorization to take marine mammals 

incidental to bridge construction and 

demolition activities at the Columbia 

River and North Portland Harbor, 

Washington and Oregon, over the course 

of 5 years from approximately July 2013 

through June 2018. Pursuant to the 

Marine Mammal Protection Act 

(MMPA), NMFS is proposing 

regulations to govern that take and 

requests information, suggestions, and 

comments on these proposed 

regulations. 

DATES: Comments and information must 

be received no later than May 21, 2012. 

ADDRESSES: You may submit comments 

on this document, identified by 

110801455–2197–01, by any of the 

following methods: 

• Electronic Submission: Submit all 

electronic public comments via the 

Federal e-Rulemaking Portal 

www.regulations.gov. To submit 

comments via the e-Rulemaking Portal, 

first click the Submit a Comment icon, 

then enter 110801455–2197–01 in the 

keyword search. Locate the document 

you wish to comment on from the 

resulting list and click on the Submit a 

Comment icon on the right of that line. 

• Hand delivery or mailing of 

comments via paper or disc should be 

addressed to Tammy Adams, Acting 

Chief, Permits and Conservation 

Division, Office of Protected Resources, 

National Marine Fisheries Service, 1315 

East-West Highway, Silver Spring, MD 

20910. 

Comments regarding any aspect of the 

collection of information requirement 

contained in this proposed rule should 

be sent to NMFS via one of the means 

provided here and to the Office of 

Information and Regulatory Affairs, 

NEOB–10202, Office of Management 

and Budget, Attn: Desk Office, 

Washington, DC 20503, 

OIRA@omb.eop.gov. 

Instructions: Comments must be 

submitted by one of the above methods 

to ensure that the comments are 

received, documented, and considered 

by NMFS. Comments sent by any other 

method, to any other address or 

individual, or received after the end of 

the comment period, may not be 

considered. All comments received are 

a part of the public record and will 

generally be posted for public viewing 

on www.regulations.gov without change. 

All personal identifying information 

(e.g., name, address) submitted 

voluntarily by the sender will be 

publicly accessible. Do not submit 

confidential business information, or 

otherwise sensitive or protected 

information. NMFS will accept 

anonymous comments (enter N/A in the 

required fields if you wish to remain 

anonymous). Attachments to electronic 

comments will be accepted in Microsoft 

Word, Excel, or Adobe PDF file formats 

only. 

FOR FURTHER INFORMATION CONTACT: Ben 

Laws, Office of Protected Resources, 

NMFS, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: 

Availability 

A copy of CRC’s application, and 

other supplemental documents, may be 

obtained by writing to the address 

specified above (see ADDRESSES), calling 

the contact listed above (see FOR

FURTHER INFORMATION CONTACT), or 

visiting the internet at: http:// 

www.nmfs.noaa.gov/pr/permits/ 

incidental.htm. A Draft Environmental 

Impact Statement (DEIS) on the 

Columbia River Crossing project, 

authored by the FTA and FHWA, is 

available for viewing at http:// 

www.columbiarivercrossing.org/. 

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.’’ 

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 

On November 22, 2010, NMFS 

received a complete application from 

CRC requesting authorization for take of 

three species of marine mammal 

incidental to construction and 

demolition activities in the Columbia 

River and North Portland Harbor, 

Washington and Oregon. CRC has 

requested regulations to be effective for 

the period of 5 years from 

approximately July 2013 through June 

2018; portions of the project that may 

result in incidental take of marine 

mammals are anticipated to potentially 

last until March 2021. Marine mammals 

would be exposed to various operations, 

including pile driving and removal, 

demolition of existing structures, and 

the presence of construction-related 

vessels. Because the specified activities 

have the potential to take marine 

mammals present within the action 

area, CRC requests authorization to 

incidentally take, by Level B harassment 

only, Steller sea lions (Eumetopias 

jubatus), California sea lions (Zalophus 

californianus), and harbor seals (Phoca 

vitulina). 

Description of the Specified Activity 

CRC is proposing a multimodal 

transportation project along a 5-mile 

section of the Interstate 5 (I–5) corridor 

connecting Vancouver, Washington, and 

Portland, Oregon. There are significant 


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congestion, safety, and mobility 

problems in the CRC project area. The 

existing northbound bridge was built in 

1917, and the southbound bridge was 

added in 1958. These bridges have been 

classified as functionally obsolete 

because they do not meet current or 

future demands for interstate service, 

resulting in congestion-related delays. 

Assuming that no changes are made, the 

daily congestion period is projected to 

grow from the current 6 hours to 15 

hours by 2030 (CRC, 2008). In addition, 

this section of I–5 has an accident rate 

more than double that of similar urban 

highways. Narrow lanes, short onramps, and non-standard shoulders on 

the bridges contribute to accidents. 

When bridge lifts occur to allow passage 

of river traffic, all vehicular traffic is 

stopped, resulting in delays on 

connecting roadways and adding to 

unsafe driving conditions. 

Current public transit service between 

Vancouver and Portland is limited to 

bus service constrained by the limited 

capacity in the I–5 corridor and is 

subject to the same congestion as other 

vehicles, which affects transit reliability 

and operations. Bicycle and pedestrian 

facilities are currently substandard in 

much of the project area. 

Seismic safety is also an important 

issue. Recent geotechnical studies have 

shown that the sandy soil under the 

mainstem Columbia River bridges 

would likely liquefy to a depth of 85 ft 

(26 m) during an earthquake greater 

than magnitude 8.0. This could cause 

irreparable damage to the bridges and 

potential loss of human life. 

To remedy these deficiencies, the CRC 

project proposes: 

• Replacement of the existing 

Columbia River bridges with two new 

structures; 

• Widening of the existing North 

Portland Harbor Bridge, and 

construction of three new structures 

across the harbor; and 

• Demolition of existing Columbia 

River bridges. 

The new Columbia River crossing 

would carry traffic on two separate piersupported bridges and would include a 

new light rail transit (LRT) line and 

improved bicycle/pedestrian facilities, 

using a stacked alignment that would 

reduce the number of in-water piers in 

the Columbia River by approximately 

one-third from alternative designs. CRC 

proposes six in-water pier complexes for 

a total of twelve piers for the Columbia 

River bridges. 

CRC proposes to widen the existing I– 

5 southbound bridge over North 

Portland Harbor, and would add three 

new bridges adjacent to the existing 

bridges. From east to west, these 

structures would carry: 

• A three-lane northbound collectordistributor (CD) ramp carrying local 

traffic; 

• Northbound and southbound I–5 on 

the widened existing bridge across the 

North Portland Harbor; 

• Southbound CD ramps carrying 

local traffic; and 

• LRT combined with a bicycle/ 

pedestrian path. 

Each bridge would have four or five 

in-water bents, consisting of one to three 

drilled shafts. A bent is part of a bridge’s 

substructure, composed of a rigid frame 

commonly made of reinforced concrete 

or steel that supports a vertical load and 

is placed transverse to the length of a 

structure. Bents are commonly used to 

support beams and girders. Each vertical 

member of a bent may be called a 

column, pier or pile. The horizontal 

member resting on top of the columns 

is a bent cap. The columns stand on top 

of some type of foundation or footer that 

is usually hidden below grade. A bent 

commonly has at least two or more 

vertical supports. 

The permanent in-water piers of both 

the Columbia River and North Portland 

Harbor crossings would be constructed 

using drilled shafts, rather than impactdriven piles. However, the project 

would require numerous temporary inwater structures to support equipment 

and materials during the course of 

construction, which may require the use 

of temporary impact-driven piles. These 

structures would include work 

platforms, work bridges, and tower 

cranes. Project construction would 

require the installation and removal of 

approximately 1,500 temporary steel 

piles. 

The existing Columbia River bridges 

would be demolished after the new 

Columbia River bridges have been 

constructed and after associated 

interchanges are operating. The existing 

Columbia River bridges would be 

demolished in two stages: (1) 

Superstructure demolition and (2) 

substructure demolition. In-water 

demolition would be accomplished 

either within cofferdams or with the use 

of diamond wire/wire saw. A full 

description of the activities proposed by 

CRC is described in the following 

sections. 

Region of Activity 

The Region of Activity is located 

within the Lower Columbia River subbasin. The Columbia River and its 

tributaries are the dominant aquatic 

system in the Pacific Northwest. The 

Columbia River originates on the west 

slope of the Rocky Mountains in Canada 

and flows approximately 1,200 mi 

(1,931 km) to the Pacific Ocean, 

draining an area of approximately 

219,000 mi2 (567,207 km2) in 

Washington, Oregon, Idaho, Montana, 

Wyoming, Nevada, and Utah. Saltwater 

intrusion from the Pacific Ocean 

extends approximately 23 mi (37 km) 

upstream from the river mouth at 

Astoria, Oregon. Coastal tides influence 

the flow rate and river level up to 

Bonneville Dam at river mile (RM) 146 

(RKm 235) (USACE, 1989). 

The project area is highly altered by 

human disturbance, and urbanization 

extends to the shoreline. There has been 

extensive removal of streamside forests 

and wetlands. Riparian areas have been 

further degraded by construction of 

dikes and levees and the placement of 

stream bank armoring. For several 

decades, industrial, residential, and 

upstream agricultural sources have 

contributed to water quality degradation 

in the river. Additionally, existing levels 

of disturbance are high due to heavy 

commercial shipping traffic. 

The I–5 bridges are located at RM 106 

(RKm 171) of the Columbia River. From 

north to south, the I–5 bridges cross the 

Columbia River from Vancouver, 

Washington, to Hayden Island in 

Portland, Oregon. From Hayden Island, 

a single I–5 bridge crosses North 

Portland Harbor to the mainland in 

Portland, Oregon. The North Portland 

Harbor is a large side channel of the 

Columbia River that flows between the 

southern bank of Hayden Island and the 

Oregon mainland. The channel branches 

off the Columbia River approximately 2 

RM (3 RKm) upstream (east) of the 

existing bridge site, and flows 

approximately 5 RM (8 RKm) 

downstream (west) before rejoining the 

mainstem Columbia River (please see 

Figure 2–2 of CRC’s application). The 

Region of Activity has been defined as 

the area of the Columbia River and 

North Portland Harbor in which marine 

mammals may be directly impacted by 

sound generated by in-water 

construction activities, i.e., the area in 

which modeling indicates that 

underwater sound generated by the 

project would be greater than 120 dB re: 

1 mPa root mean square (rms; all 

underwater sound discussed in this 

document is referenced to 1 mPa). 

Due to the curvature of the river and 

islands present, underwater sound from 

pile installation would encounter land 

before it reaches modeled distances to 

the 120 dB disturbance threshold. 

Sound from pile installation could not 

extend beyond Sauvie Island, 

approximately 5.5 RM (8.9 RKm) 

downstream, and Lady Island, 12.5 RM 

(20 RKm) upstream; thus, this distance 


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represents the extent of the Region of 

Activity downstream and upstream of 

CRC project construction activities. This 

distance encompasses the Columbia 

River from approximately RM 101 to 

118 (RKm 163 to 190). Within North 

Portland Harbor, the maximum distance 

that underwater sound could extend 

would be 3.5 mi (5.6 km) downstream 

and 1.9 mi (3.1 km) upstream of CRC 

project construction activities. 

Dates of Activity 

CRC has requested regulations 

governing the incidental take of marine 

mammals for the 5-year period from July 

2013 through June 2018. Construction 

activities for both the Columbia River 

and North Portland Harbor bridges are 

estimated to begin in July 2013. 

Construction activities for the Columbia 

River bridges are estimated to end in 

2017, while construction activities for 

the North Portland Harbor bridges are 

estimated to end in 2016. Demolition of 

the existing Columbia River bridges is 

expected to occur for eighteen months, 

from approximately September 2019 

until March 2021. However, some 

demolition could possibly occur during 

the proposed 5-year authorization 

period. Table 1 provides an overview of 

the anticipated CRC project timeline 

and sequencing of project elements. 

Funding would be a significant factor in 

determining the overall sequencing and 

construction duration. Contractor 

schedules, weather, materials, and 

equipment could also influence 

construction duration. CRC would seek 

additional authorization under the 

MMPA for any in-water work 

continuing beyond the expiration of the 

proposed rule. 

The existing in-water work window 

for this portion of the Columbia River 

and North Portland Harbor, developed 

to reduce construction impacts to 

Endangered Species Act (ESA)-listed 

fish species, is November 1 through 

February 28. Because of the large 

amount of in-water work required, the 

CRC project would not be able to 

complete the in-water work during this 

time period. Therefore, CRC has 

requested a variance to the in-water 

work window established by the Oregon 

and Washington Departments of Fish 

and Wildlife (ODFW and WDFW, 

respectively). Most in-water 

construction activities are proposed to 

occur year-round, although impact pile 

driving would occur only from 

September 15 to April 15. The rationale 

for CRC’s proposed variance takes into 

account project hydroacoustic impacts 

in relation to run timing for ESA-listed 

fish species. The project’s timing for 

impact pile driving overlaps with 

pinniped presence (primarily January 

through May) from approximately 

January through April 15. 

TABLE 1—PROPOSED TIMING OF IN-WATER WORK

[CR = Columbia River; NPH = North Portland Harbor] 

Activity Description Activity duration Timing 

1. Install small-diameter piles (less 

than or equal to 48 in (1.2 m)) 

with impact methods 1.

Small-diameter piles would be 

used in the construction of temporary work bridges/platforms, 

tower cranes, and support platforms.

45 min/day (impact hammer operation) with up to 7.5 min/week 

of unattenuated driving in CR 

and 5 min/week of 

unattenuated driving in NPH.

138 days in CR, 134 days in NPH 

Only within approved extended inwater work window of September 15 through April 15 

each year. 

2. Install small-diameter piles with 

non-impact methods.

Small-diameter piles would be 

used in the construction of temporary work bridges/platforms, 

barge moorings, tower cranes, 

and oscillator support platforms.

Length of work day is subject to 

local sound ordinances, however could be up to 24 hours/ 

day.

138 days in CR, 134 days in NPH 

Year-round provided work does 

not violate water quality standards.2

3. Extract small-diameter piles (not 

including cofferdams).

Removal of small-diameter piles 

would be done using vibratory 

equipment or direct pull.

Length of work day is subject to 

local sound ordinances, however could be up to 24 hours/ 

day.

Year-round provided work does 

not violate water quality standards. 

4. Install/remove cofferdam for 

construction of Columbia River 

bridges.

Used to construct piers nearest to 

shore in the Columbia River 

(Pier complexes 2 and 7). Steel 

sheet pile sections to be installed by non-impact means to 

form a cofferdam. Sheet pile removal can be direct pull or use 

a vibratory hammer.

Cofferdams could be in place for 

a maximum of 250 work days 

each. Installation and 

dewatering of each cofferdam 

would not take more than 65 

work days; cofferdam removal 

would not take more than 25 

work days. Length of work day 

is subject to local sound ordinances.

Year-round provided work does 

not violate water quality standards. 

5a. Install large-diameter drilled 

shaft casings (greater than or 

equal to 72 in (1.8 m)) using vibratory hammer, rotator, or oscillator outside of a cofferdam.

Used to construct piers and bents 

not immediately adjacent to 

shore in the Columbia River 

and North Portland Harbor.

CR: 110–120 days/pier complex ..

NPH: approximately 8 days/shaft. 

Year-round provided work does 

not violate water quality standards. 

5b. Install large-diameter drilled 

shaft casings using vibratory 

hammer, rotator, or oscillator inside of a water- or sand-filled 

cofferdam.

Used to construct piers and bents 

nearest to shore in the Columbia River and North Portland 

Harbor.

CR pier complexes 2 and 7: approximately 84 days each.

NPH: approximately 8 days/shaft. 

Year-round provided work does 

not violate water quality standards. 

6. Clean out shafts and place reinforcing and concrete inside steel 

casings.

Applies to all piers and shafts. All 

activities/materials would be 

contained within the casings 

and have no contact with the 

water.

CR: 110–120 days/pier complex ..

NPH: approximately 8 days/shaft. 

Year-round provided work does 

not violate water quality standards. 


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TABLE 1—PROPOSED TIMING OF IN-WATER WORK—Continued 

[CR = Columbia River; NPH = North Portland Harbor] 

Activity Description Activity duration Timing 

7a. Perform placement of reinforcement and concrete for a 

cast-in-place pile cap.

Possible construction method for 

shaft cap at pier complexes 2 

and 7. All activities and materials would be contained within 

forms and would have no contact with the water. The bottom 

of the pier caps may sit below 

the mud line.

Estimate 95 work days per pier ... Year-round. For pier caps nearest 

shore: year-round if work occurs within a de-watered 

cofferdam. 

7b. Place a prefabricated pile cap, 

form, pile template, or similar 

element into the water.

At CR pier complexes 3–6. Potentially at pier complexes 2 and 7. 

Assume contact with the water 

surface, but not with the riverbed.

100 work days per pier ................. For deep water piers: year-round 

provided work does not violate 

water quality standards. For 

piers nearest shore: year-round 

if work occurs within a de-watered cofferdam. 

8. Install and remove cofferdam for 

demolition of existing Columbia 

River bridges.

Steel sheet pile sections would be 

installed with a vibratory hammer or pushed in, to form a 

cofferdam. Sheet pile removal 

can be direct pull or with a vibratory hammer. More than one 

cofferdam is to be in use at a 

time.

Approximately 370 days ...............

Installation: 10 work days per 

pier, Demolition: 20 work days 

per pier, Removal: 10 work 

days per pier. 

Year-round provided work does 

not violate water quality standards. 

9a. Perform wire saw/diamond 

wire cutting outside of a 

cofferdam at or below the water 

surface.

Used throughout for demolition of 

existing bridges to cut concrete 

piers into manageable pieces. 

These pieces would then be 

loaded onto barges and transported off site.

Pier cutting and removal to take 

approximately 7 work days per 

pier.

Year-round provided work does 

not violate water quality standards. 

9b. Perform wire saw/diamond 

wire cutting or a hydraulic breaker inside of a cofferdam.

Used for demolition of the existing 

Columbia River bridges. Used 

in water to cut concrete piers 

into manageable pieces. 

Cofferdam would not be 

dewatered.

Pier cutting and removal to take 

approximately 7 work days per 

pier.

Year-round provided work does 

not violate water quality standards. 

10. Remove material from river 

bed.

Old pier/bent foundations or riprap 

from North Portland Crossing 

would be removed if obstructing 

construction. Would use bucket 

dredge.

Less than 7 work days during the 

published standard in-water 

work window per pier.

No variance requested. November 

1 to February 28. 

10a. Spot remove debris and 

riprap from river bed.

Guided removal (likely underwater 

diver assisted) of specific 

pieces of debris or large riprap 

only in the location where the 

shaft would be drilled. In North 

Portland Harbor only. Would 

use bucket dredge.

Up to 2 hrs/day. Less than 7 work 

days.

Year-round provided work does 

not violate water quality standards. 

Note: Proposed timing is contingent upon obtaining an in-water work variance from all relevant regulatory agencies. 1To reduce number of impact pile strikes, temporary piles that are load-bearing would be vibrated to refusal, then driven and proofed with an 

impact hammer to confirm load-bearing capacity. 2 In the event water quality monitoring determines that work exceeds water quality standards, all in-water work would be suspended until corrective measures can be implemented. 

Description of the Activity—Columbia 

River Bridges 

The project would construct two new 

bridges across the Columbia River 

downstream (to the west) of the existing 

interstate bridges. Each of the structures 

would range from approximately 91 to 

136 ft (28–41 m) wide, with a gap of 

approximately 15 ft (5 m) between them. 

The over-water length of each new 

mainstem bridge would be 

approximately 2,700 ft (823 m). 

The Columbia River bridges would 

consist of six in-water pier complexes of 

two piers each, for a total of twelve inwater piers. Piers 3–6 would each have 

separate structures for the northbound 

and southbound bridges. Each pier 

would consist of up to nine 10-ftdiameter (3 m) drilled shafts topped by 

a shaft cap (see Figure 1–4 of CRC’s 

application for illustration). Pier 

complexes 2 through 7 are in-water, 

beginning on the Oregon side. Pier 

complex 1 would be on land in Oregon, 

while pier complex 8 would be on land 

in Washington. Portions of pier complex 

7 occur in shallow water (less than 20 

ft [6 m] deep). The basic configuration 

of these bridges, the span lengths, and 

the layout of the bridges relative to the 

Columbia River shoreline and 

navigation channels are illustrated in 

Figure 1–2 of CRC’s application. 

The proposed Columbia River 

mainstem crossing design uses dual 

stacked bridge structures, which 

reduces the number of in-water piers in 

the Columbia River by approximately 

one-third compared with alternative 

designs, and greatly reduces both the 

temporary construction impacts and the 

permanent effects of in-water piers. The 

western structure would carry 

southbound I–5 traffic on the top deck, 


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with LRT on the lower deck. The 

eastern structure would carry 

northbound I–5 traffic on the top deck, 

with bicycle/pedestrian traffic on the 

lower deck. 

At each pier complex, sequencing 

would occur as listed below. Details of 

each activity are presented in following 

sections. 

• Install temporary cofferdam 

(applies to pier complexes 2 and 7 

only). 

• Install temporary piles to moor 

barges and to support temporary work 

platforms (at pier complexes 3 through 

6) and work bridges (at pier complexes 

2 and 7). 

• Install drilled shafts for each pier 

complex. 

• Remove work platform or work 

bridge and associated piles. 

• Install shaft caps at the water level. 

• Remove cofferdam (applies to pier 

complexes 2 and 7 only). 

• Erect tower crane. 

• Construct columns on the shaft 

caps. 

• Build bridge superstructure 

spanning the columns. 

• Remove tower crane. 

• Connect superstructure spans with 

mid-span closures. 

• Remove barge moorings. 

A construction sequence was 

developed for building the new 

Columbia River bridges and 

demolishing the existing structures (see 

Figure 1–5 of CRC’s application). Once 

a construction contract is awarded, the 

contractor may sequence the 

construction in a way that may not 

conform exactly to the proposed 

schedule but that best utilizes the 

materials, equipment, and personnel 

available to perform the work. However, 

the amount of in-water work that can be 

conducted at any one time is limited, 

and is based on three factors: 

1. The amount of equipment available 

to build the project would likely be 

limited. Based on equipment 

availability, the CRC engineering team 

estimates that only two drilled shaft 

operations could occur at any time. 

2. The physical space the equipment 

requires at each pier would be 

substantial. The estimated sizes of the 

work platforms/bridges and associated 

barges are shown in Appendix A of 

CRC’s application. This is a conceptual 

design developed by the CRC project 

team to provide a maximum area of 

impact. The actual work platforms 

would be designed by the contractor; 

therefore, actual sizes would be 

determined at a later date. The overlap 

of work platforms/bridges and barge 

space limits the amount and type of 

equipment that can operate at a pier 

complex at one time. 

3. The U.S. Coast Guard has required 

that one navigation channel be open at 

all times during construction, to the 

extent feasible. 

All the activities listed above may 

occur at more than one pier complex at 

a time. Please see Appendix A of CRC’s 

application for conceptual diagrams of 

the construction sequence. 

Temporary Structures—Pier 

complexes 2 and 7 would each require 

one temporary cofferdam. Cofferdams 

would consist of interlocking sections of 

sheet piles to be installed with a 

vibratory hammer or with press-in 

methods. Cofferdams would be removed 

using a vibratory hammer or direct pull. 

Additionally, the project would 

include numerous temporary in-water 

structures to support equipment and 

materials during the course of 

construction. These structures would 

include work platforms, work bridges, 

and tower cranes. They would be 

designed by the contractor after a 

contract is awarded, but prior to 

construction. 

Work platforms, which would 

surround the future location of each 

shaft cap, would be constructed at pier 

complexes 3 through 6. A conceptual 

design of a temporary in-water work 

platform may be found in CRC’s 

application (Figure 11 of Appendix A). 

Work bridges would be installed at pier 

complexes 2 and 7 so that equipment 

can access these pier complexes directly 

from land. Temporary work bridges 

would be placed only on the landward 

side of these pier complexes. The 

bottom of the temporary work platforms 

and bridges would be a few feet above 

the water surface. The decks of the 

temporary work structures would be 

constructed of large, untreated wood 

beams to accommodate large equipment, 

such as 250-ton cranes. After drilled 

shafts and shaft caps have been 

constructed, the temporary work 

platforms and their support piles would 

be removed. 

After work platforms/bridges are 

removed at a given pier complex, one 

tower crane would be constructed 

between each pair of adjacent piers that 

makes up the pier complex. The crane 

would construct the bridge columns and 

the superstructure. Following 

construction of the columns and 

superstructure, the tower cranes and 

their support piles would be removed. 

Steel pipe piles would be used to 

support the temporary support 

structures. In addition, four temporary 

piles could surround each of the drilled 

shafts. Due to the heavy equipment and 

stresses placed on the support 

structures, all of these temporary piles 

would need to be load-bearing. Loadbearing piles would be installed using a 

vibratory hammer and then proofed 

with an impact hammer to ensure that 

they meet project specifications 

demonstrating load-bearing capacity. 

The number and size of temporary piles 

for these structures is listed in Table 2. 

TABLE 2—SUMMARY OF STEEL PIPE PILES AND TEMPORARY STRUCTURES REQUIRED FOR CONSTRUCTION OF COLUMBIA

RIVER BRIDGES

Structure Number Pile diameter Pile length Piles per 

structure 

Total 

number 

of piles 

Duration present in 

water (days-each) 

Work platforms/ 

bridges.

6 ......... 18–24 in (0.5–0.6 m) ................... 70–90 ft (21–27 m) ...................... 100 ........... 600 260–315. 

42–48 in (1.1–1.2 m) ................... 120 ft (37 m) ................................ 32 ............ 192 

Tower cranes 6 ......... 42–48 in ....................................... 120 ft ............................................ 8 ............... 48 150–275. 

Barge moorings.N/A ..... 18–24 in ....................................... 70–90 ft ........................................ Varies ...... 80 120/mooring. 

Barges (cumulative, at 

a single 

time).

Up to 

12.

N/A ............................................... N/A ............................................... N/A ........... N/A Varies. 

Total ...... Varies ...................................................... ...................................................... .................. 920 


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Barges would be used as platforms to 

conduct work activities and to haul 

materials and equipment to and from 

the work site. Barges would be moored 

to non-load-bearing steel pipe piles and 

adjacent to temporary work structures. 

Several types and sizes of barges would 

be used for bridge construction. The 

type and size of a barge would depend 

on how the barge is used. No more than 

twelve barges are estimated to be 

moored or active in the Columbia River 

at any one time throughout the 

construction period. Barges would be 

moored around each pier complex. 

Approximately eighty mooring piles 

would be installed over the life of the 

project, each in place for approximately 

120 work days. Mooring piles would be 

vibrated into the sediment until refusal. 

Vibratory installation would take 

between 5–30 minutes per pile. 

The number of temporary platforms or 

bridges in the Columbia River at one 

time would vary between zero and three 

during construction. Up to four work 

platforms and two work bridges would 

be required to install drilled shafts and 

construct shaft caps. Each work 

platform/bridge would require 22 to 25 

work days to install. Each work 

platform/bridge would be in place for 

approximately 260 to 315 work days. 

Each tower crane would require 

approximately two work days to drive 

support piles and an additional thirteen 

work days to construct the platform. 

Each tower crane would be in place for 

approximately 150 to 275 work days. 

Load-bearing piles (used for work 

platforms/bridges and tower cranes) 

would be vibrated to refusal 

(approximately 5–30 minutes per pile), 

then driven and proofed with an impact 

hammer to confirm load-bearing 

capacity. An average of six temporary 

piles would be installed per day using 

vibratory installation to set the piles, 

and up to two impact drivers to proof 

them. Rates of installation would be 

determined by the type of installation 

equipment, substrate, and required loadbearing capacity of each pile. 

Temporary piles would be installed and 

removed throughout the construction 

process. No more than two impact pile 

drivers would operate at one time. Use 

of two impact pile drivers would 

primarily occur within a single pier 

complex. 

In general, temporary piles would 

extend only into the alluvium to an 

approximate depth of 70 to 120 ft (21– 

37 m). Standard pipe lengths are 80 to 

90 ft (24–27 m), so some piles may need 

to be spliced to achieve these depths. 

Estimated pile installation 

specifications are provided in Table 3. 

The number of pile strikes was 

estimated by Washington Department of 

Transportation (WSDOT) geotechnical 

and CRC project engineers, based on 

information from past projects and 

knowledge of site sediment conditions. 

The actual number of pile strikes would 

vary depending on the type of hammer, 

the hammer energy used, and substrate 

composition. The strike interval of 1.5 

seconds (forty strikes per minute) is also 

estimated from past projects and is 

based on use of a diesel hammer. This 

estimate is within the typical range of 

35–52 strikes per minute for diesel 

hammers (HammerSteel, 2009). As 

shown in Table 3, for any one 12-hour 

daily pile driving period, less than 1 

hour of pile driving would occur. Please 

see Table 8 for a summary of time 

required for vibratory driving. 

TABLE 3—PILE STRIKE SUMMARY FOR CONSTRUCTION IN COLUMBIA RIVER

Pile Size Estimated piles 

installed per day 

Estimated strikes 

per pile 

Estimated 

maximum strikes 

per day 

Hours of pile 

driving per 12-hr 

daily pile driving 

work period* 

18–24 in (0.5–0.6 m) ............................................................... 2 300 600 0.25 

42–48 in (1.1–1.2 m) ............................................................... 4 300 1,200 0.50 

Total .................................................................................. 6 N/A 1,800 0.75 

* This scenario assumes just one pile being driven at a time. During construction, up to two piles may be driven at the same time in the Columbia River. If this were to occur, the strike numbers would stay the same, but the actual driving time would decrease. 

A sound attenuation device (i.e., 

bubble curtain) would be used during 

all impact pile driving, with the 

exception of periods when the device 

would be turned off to measure its 

effectiveness, in accordance with the 

hydroacoustic monitoring plan. A 

period of up to 7.5 min per week of pile 

driving without the use of an 

attenuation device has been allocated in 

analyses of project impacts, to allow for 

this study of mitigation effectiveness, as 

well as for instances when the device 

might fail. If the attenuation device fails, 

pile driving activities would shut down 

as soon as practicable and resolution of 

the problem would occur; however, 

some amount of unattenuated driving 

may occur before shut-down can safely 

occur. By incorporating this time into 

the analysis, the project may still 

proceed in the event of an equipment 

failure without exceeding analyzed 

thresholds. With the exception of 

hydroacoustic monitoring, intentional 

impact pile driving without a sound 

attenuation device is not proposed nor 

would it be authorized. In addition, to 

limit hydroacoustic impacts to marine 

mammals, there would be, at minimum, 

a consecutive 12-hour period without 

impact pile driving for every 24-hour 

day. 

Permanent Structures—In-water 

drilled shaft construction is 

accomplished by installing large 

diameter steel casing to a specified 

depth (up to ¥270 ft (¥82 m) North 

American Vertical Datum of 1988) to the 

top of the competent geological layer, 

which is the Troutdale Formation in the 

project area. The top layer of river 

substrate is composed of loose to very 

dense alluvium (primarily sand and 

some fines), beneath which is 

approximately 20 ft (6 m) of dense 

gravel, underlain by the Troutdale 

Formation. 

A vibratory hammer, oscillator, or 

rotator would be used to advance a 

casing. If casings are installed by a 

vibratory hammer, installation is 

estimated to be 1 work day per casing. 

If casings need to be welded together, 1 

work day is estimated for the weld. No 

more than two casings are estimated per 

shaft. Soil would be removed from 

inside the casing and transferred onto a 

barge as the casing is advanced, and the 

soil would be deposited at an approved 

upland site. Drilling would continue 

below the casing approximately 30 ft (9 

m) into the Troutdale Formation to a 

specified tip elevation. After excavating 

soil from inside the casing, reinforcing 

steel would be installed into the shaft 

and then the shaft would be filled with 

concrete. 

During construction of the drilled 

shafts, uncured concrete would be 

poured into water-filled steel casings, 

creating a mix of concrete and water. As 


tkelley on DSK3SPTVN1PROD with PROPOSALS2
23554 Federal Register / Vol. 77, No. 76 / Thursday, April 19, 2012 / Proposed Rules 

the concrete is poured into the casing, 

it would displace this highly alkaline 

mixture. The project would implement 

best management practices (BMPs) to 

contain the mixture and ensure that it 

does not enter any surface water body. 

Once contained, the water would be 

treated to meet state water quality 

standards and either released to a 

wastewater treatment facility or 

discharged to a surface water body. The 

steel casing may or may not be removed, 

depending on the installation method. 

Figures 1–6 through 1–9 of CRC’s 

application depict typical drilled shaft 

operations and equipment. 

The total duration of the permanent 

shaft installation could vary 

considerably depending on the type of 

installation equipment used, the 

quantity of available installation 

equipment, and actual soil conditions. 

Installation of each drilled shaft is 

estimated to take approximately 10 

days. With the limited in-water work 

window for impact pile driving and 

construction phasing constraints, the 

total duration of drilled shaft 

installation would be approximately 

thirty months. For each of the in-water 

pier complexes (Piers 2–7), six to nine 

shafts would be drilled. For piers 3–6, 

which would support separate 

northbound and southbound bridges, 

this means a minimum of 48 drilled 

shafts. For piers 2 and 7, which would 

support a unified structure, there would 

be a minimum of twelve drilled shafts. 

At minimum, there would be an overall 

total of 72 drilled shafts. 

Precast shaft caps would be placed on 

top of the drilled shafts. Installation of 

the shaft caps would require cranes, 

work barges, and material barges. 

Columns would be constructed of castin-place reinforced concrete or precast 

concrete. Column construction is 

estimated to take 120 days for each pier 

complex. Construction of columns 

would require cranes, work barges, and 

material barges in the river year-round. 

The superstructure would be 

constructed of structural steel, cast-inplace concrete, or precast concrete. 

Precast elements would be fabricated at 

a casting yard. 

Description of the Activity—North 

Portland Harbor Bridges 

The existing North Portland Harbor 

bridge would be upgraded to meet 

current seismic standards. The seismic 

retrofit activities would consist solely of 

minor modifications to the bent caps 

and girders that would not require inwater work. In addition, four new bridge 

structures would be constructed across 

North Portland Harbor. The bridges, 

illustrated in Figure 1–12 of CRC’s 

application are, from west to east: the 

LRT/pedestrian/bicycle bridge, I–5 

southbound off-ramp, I–5 southbound 

on-ramp, existing mainline, and I–5 

northbound on-ramp. 

The existing North Portland Harbor 

bridge was constructed in the early 

1980s of prestressed concrete girders 

and reinforced concrete bents. The bents 

are supported by driven steel pilings. 

Two previous bridges, constructed in 

1917 and 1958, were built at the same 

location as the current bridge, but may 

not have been fully removed during 

subsequent replacement efforts. These 

bridges had reinforced concrete bents 

supported on timber piles. Some of this 

material may still be present, but this 

would not be confirmed until 

construction begins. Some removal of 

previous bridge elements is anticipated 

prior to installation of the new bridge 

shafts. Removal of remnant bridge 

elements would be with a clamshell 

dredge. The five new or improved 

bridges over the North Portland Harbor 

would range from approximately 900– 

1,000 ft (274–305 m) over water, and 

would range from 40–150 ft (12–46 m) 

in width. Bridge widths would vary due 

to merging of lanes on some structures. 

Construction is expected to be 

sequential, beginning with either of the 

most nearshore bents of a given bridge 

and proceeding to the adjacent bent. 

The actual sequencing would be 

determined by the contractor once a 

construction contract is awarded. No 

more than three of the five bridges are 

likely to have in-water work occurring 

simultaneously. For the bents closest to 

shore, construction would occur from 

work bridges. At the other in-water 

bents, as described for Columbia River 

bridges, construction would likely occur 

from barges and support platforms. 

General construction activities to build 

the bents and superstructure are similar 

to those for the Columbia River bridges, 

except that shaft caps would not be used 

and bridge decks would be placed on 

girders instead of balanced cantilevers. 

General sequencing of the construction 

of a single bridge appears below. Some 

of these activities may occur 

simultaneously at separate bents. 

• Construct support platforms and 

work bridges using vibratory and impact 

pile drivers. 

• Vibrate temporary piles for barge 

moorings. 

• Extract large pieces of debris as 

needed to allow casings to advance. 

• Install drilled shafts at each bent. 

• Construct columns on the drilled 

shafts. 

• Construct a bent cap or crossbeam 

on top of the columns at a bent location. 

• Erect bridge girders on the bent 

caps or crossbeams. 

• Place the bridge deck on the girders. 

• Remove temporary work bridges, 

support platforms, and supporting piles. 

Temporary Structures—At the bents 

closest to shore, up to nine temporary 

work bridges would be constructed to 

support equipment for drilled shafts. In 

addition, at each of the 31 bent 

locations, one support platform would 

be constructed, each consisting of four 

load-bearing piles. The bridges and 

support platforms would be designed by 

the contractor after a contract is 

awarded, but prior to construction. The 

number and size of piles for temporary 

in-water work structures are listed in 

Table 4. 

TABLE 4—APPROXIMATE NUMBER OF STEEL PIPE PILES REQUIRED FOR CONSTRUCTION OF NORTH PORTLAND HARBOR

BRIDGES

Structure Number Pile diameter Pile length Piles per 

structure 

Total 

number 

of piles 

Duration present in 

water 

(days-each) 

Work bridges .................. 9 ................... 18–24 in (0.5–0.6 m) .... 70–120 ft (21–37 m) ..... 25 225 20–42. 

Support platforms ........... 31 ................. 36–48 in (0.9–1.2 m) .... 120 ft ............................. 4 124 10–34. 

Barge moorings .............. N/A ............... 36–48 in ........................ 120 ft ............................. N/A 216 30/mooring. 

Barges (cumulative, at a 

single time).

Up to 9 ......... N/A ................................ N/A ................................ N/A N/A 10–34. 

Total ........................ Varies ........... ....................................... ....................................... .................... 565 


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As with the mainstem Columbia River 

bridges, temporary piles would be 

required to support in-water work 

bridges or to moor barges during 

construction of the North Portland 

Harbor bridges. Unlike the Columbia 

River bridges, cofferdams are not 

necessary. Piles used for the temporary 

work bridges and the support platforms 

must be load bearing. They would first 

be vibrated to refusal, and then proofed 

with an impact hammer to confirm loadbearing capacity. An average of three 

load-bearing piles would be installed 

per day using vibratory installation to 

set the piles, with one impact driver to 

proof. Rates of installation would be 

determined by the type of installation 

equipment, substrate, and required loadbearing capacity of each pile. 

Temporary mooring piles would be 

installed and removed throughout the 

construction process. Installation of 

these mooring piles could occur yearround and at any time during sufficient 

visibility. These piles would be 

installed using vibratory methods only. 

In general, temporary piles would 

extend only into the alluvium to an 

estimated depth of 70 to 120 ft (21–37 

m). Standard pipe lengths are 80 to 90 

ft (24–27 m), so some piles may need to 

be welded to achieve the lengths 

required to drive them to these depths. 

Estimated pile installation 

specifications are provided in Table 5. 

Estimates of required number of strikes 

per pile and total strikes are the same as 

for the Columbia River. However, only 

one impact driver at a time would be 

used. Impact pile driving is proposed to 

occur only during a modified in-water 

work period from approximately 

September 15 to April 15. No impact 

pile driving would occur outside of the 

approved dates. 

As discussed for Columbia River, a 

sound attenuation device (i.e., bubble 

curtain) would be used during all 

impact pile driving, with the exception 

of periods when the device would be 

turned off to measure its effectiveness, 

in accordance with the hydroacoustic 

monitoring plan. A period of up to 5 

minutes per week of pile driving 

without the use of an attenuation device 

has been allocated in analyses of project 

impacts for North Portland Harbor, to 

allow for this study of mitigation 

effectiveness, as well as for instances 

when the device might fail. If the 

attenuation device fails, pile driving 

activities would shut down as soon as 

practicable and resolution of the 

problem would occur; however, some 

amount of unattenuated driving may 

occur before shut-down can safely 

occur. By incorporating this time into 

the analysis, the project may still 

proceed in the event of an equipment 

failure without exceeding analyzed 

thresholds. With the exception of 

hydroacoustic monitoring, intentional 

impact pile driving without a sound 

attenuation device is not proposed nor 

would it be authorized. In addition, to 

limit hydroacoustic impacts to marine 

mammals, there would be, at minimum, 

a consecutive 12-hour period without 

impact pile driving for every 24-hour 

day. Please see Table 8 for a summary 

of time required for vibratory driving. 

TABLE 5—PILE STRIKE SUMMARY FOR CONSTRUCTION IN NORTH PORTLAND HARBOR

Pile size Estimated piles 

installed per day 

Estimated strikes 

per pile 

Estimated 

maximum strikes 

per day 

Hours of pile 

driving per 12-hr 

daily pile driving 

work period 

18–24 in (0.5–0.6 m) ............................................................. 3 300 900 0 .375 

36–48 in (0.9–1.2 m) ............................................................. 3 300 900 0 .375 

Total ................................................................................ 6 N/A 1,800 0 .75 

Barges would be used as platforms for 

conducting work activities and to haul 

materials and equipment to and from 

the work site. Barges would be moored 

with steel pipe piles adjacent to 

temporary work bridges or bents. 

Several types and sizes of barges would 

be used according to specific function. 

No more than nine barges are estimated 

to be present in North Portland Harbor 

at any one time during the construction 

period. 

Following installation of the drilled 

shafts, the temporary work structures 

and their support piles would be 

removed through vibratory methods. 

Other temporary piles would be 

installed to moor barges adjacent to the 

new bents. These non-load bearing piles 

would be installed through vibratory 

methods only. The installation of steel 

pipe piles would occur throughout the 

construction period. Steel piles would 

be installed and removed during the 

multi-year construction of the 

temporary support structures. Although 

the project would use over 500 piles in 

the North Portland Harbor, only 100 to 

200 piles are estimated to be in the 

water at any one time. 

Debris Removal—Debris from 

previous structures, including 

foundations from the 1917 and 1953 

bridges, may be present in North 

Portland Harbor at some locations 

where drilled shafts would be installed. 

This debris is likely to consist of large 

rock or old concrete. Because casings 

cannot advance through this type of 

material, it must be removed. Removal 

would consist of capturing the debris in 

a clamshell bucket. Capture of sediment 

would be limited. Debris would be 

placed in an upland location, and 

disposed of at a landfill if appropriate. 

Debris removal activities would be 

limited to the designated in-water work 

window of November 1 through 

February 28. Removal activities would 

take no more than 10 days over the 

course of construction. 

Before debris removal begins, divers 

would pinpoint the location of the 

material. Debris removal would only 

occur in the precise locations where 

material overlaps with the footprint of 

the new shafts, greatly minimizing the 

areal extent of the activity. The amount 

of material in this location is unknown; 

however, assuming a worst-case 

scenario (that the area of the material is 

the same as the footprint of the drilled 

shafts), the project would remove debris 

in no more than 31 locations over an 

area of roughly 2,433 ft2 (226 m2). No 

more than 90 yd3 (69 m3) of material 

would be removed. If any items are 

found during excavation that contain 

potential contaminants (e.g., buried 

drums, car bodies containing petroleum 

products), activities to control and clean 

up contaminants would be implemented 

in accordance with the project’s 

approved Spill Prevention, Control, and 

Countermeasures (SPCC) plan. 

Permanent Structures—In-water 

drilled shaft construction for the North 

Portland Harbor would occur as 

described for the Columbia River 

bridges. Installation of each drilled shaft 

is estimated to take approximately 10 

days. However, the total duration of this 

activity could vary considerably 

depending on the type of equipment 


tkelley on DSK3SPTVN1PROD with PROPOSALS2
23556 Federal Register / Vol. 77, No. 76 / Thursday, April 19, 2012 / Proposed Rules 

used, the quantity of available 

equipment, and on-site soil conditions. 

The total duration of drilled shaft 

installation would be approximately 

eighteen months. A maximum of 31 

shafts would be installed for the North 

Portland Harbor bridges. Each bridge 

would have four to seven spans, each a 

maximum of 255 ft (78 m) long. Each 

new bridge would have three to five inwater bents, consisting of one to three 

10-ft diameter (3 m) drilled shafts. 

Unlike the Columbia River piers, shafts 

would not be topped by a shaft cap. 

Current designs place all of the bents in 

shallow water (less than 20 ft (6 m) 

deep). 

Columns would be constructed of 

cast-in-place reinforced concrete. 

Construction of cast-in-place columns 

would require cranes, work barges, and 

material barges continuously throughout 

this period. The superstructure would 

consist of girders and a deck. Girders 

would be constructed of structural steel, 

cast-in-place concrete, or precast 

concrete. Precast girders may be 

fabricated at a casting yard. A cast-inplace concrete deck would be placed on 

the girders. 

Description of the Activity—Columbia 

River Bridge Demolition 

The existing Columbia River bridges 

would be demolished after the new 

Columbia River bridges have been 

constructed and after associated 

interchanges are operating. The existing 

Columbia River bridges would be 

demolished in two stages: (1) 

Superstructure demolition and (2) 

substructure demolition. 

Demolition of the superstructure 

would begin with removal of the 

counterweights. The lift span would be 

locked into place and the 

counterweights would be cut into pieces 

and transferred off-site via truck or 

barge. Next, the lift towers would be cut 

into manageable pieces and loaded onto 

barges by a crane. Prior to removal of 

the trusses, the deck would be removed 

by cutting it into manageable pieces; 

these pieces would be transported by 

barge or truck or by using a breaker, in 

which case debris would be caught on 

a barge or other containment system 

below the work area. After demolition of 

the concrete deck, trusses would be 

lifted off of their bearings and onto 

barges and transferred to a shoreline 

dismantling site. 

The existing Columbia River bridge 

structures comprise eleven pairs of steel 

through-truss spans with reinforced 

concrete decks, including one pair of 

movable spans over the primary 

navigation channel and one pair of 531- 

ft long (162 m) span trusses. The 

remaining nine pairs of trusses range 

from 265 to 275 ft (81–84 m) in length. 

In addition to the trusses, there are 

reinforced concrete approach spans 

(over land) on either end of the bridges. 

Nine sets of the eleven existing 

Columbia River bridge piers are below 

the ordinary high water (OHW) level 

and are supported on a total of 

approximately 1,800 driven timber 

piles. Demolition methods are not 

finalized; however, the final design 

would consider factors such as pier 

depth, safety, phasing constraints, and 

impacts to aquatic species. Demolition 

of the concrete piers and timber piling 

foundations would be accomplished 

using one of two methods: 

1. After removal of the trusses, a 

cofferdam would be installed at each of 

the nine in-water bridge piers to contain 

demolition activities. Cofferdams would 

not be dewatered. The piers would be 

broken up and removed from within the 

cofferdam. Timber piles that pose a 

navigation hazard would then be 

extracted or cut off below the mud line. 

2. A diamond wire/wire saw would be 

used to cut the piers into manageable 

chunks that would be transported 

offsite. Cofferdams would not be used. 

Timber piles would then be extracted or 

cut off below the mud line. With either 

method, the pieces of the piers would be 

removed via barge. 

Although maintenance personnel 

regularly inspect the existing bridge, the 

timber piles located underneath the 

existing piers are inaccessible and have 

not been inspected. Therefore, it is 

unknown whether these timber piles 

have been treated with creosote, but 

given their age and intended purpose, it 

is assumed that they have been so 

treated. Only piles that could pose a 

navigation hazard would be removed or 

cut off below the mud line. These piles 

include those that are present in the 

proposed navigation channels and any 

that extend above the surface of the 

river bed. Piles would be removed 

(using a vibratory extractor, direct pull, 

or clam shell dredge) or cut off below 

the mud line using an underwater saw. 

The exact number of piles to be 

removed is unknown. 

A conceptual demolition sequence 

was determined based on the amount of 

equipment likely available to build the 

project and the physical space the 

equipment requires at each pier. The 

sequence is provided in Appendix A, 

Figures 12–16 of CRC’s application. The 

actual construction sequence would be 

determined by the contractor once a 

construction contract is awarded. 

Demolition would occur after the new 

Columbia River replacement bridges are 

built. Demolition activities would take 

approximately eighteen months, from 

approximately September 2019 until 

March 2021. However, some demolition 

activities could occur during the period 

of this proposed rule. 

Temporary Structures—Temporary 

cofferdams would be required to isolate 

work activities and temporary piles 

would be installed to anchor work and 

material barges during demolition of the 

spans and in-water piers. If the diamond 

wire/wire saw is not used, a temporary 

cofferdam consisting of interlocking 

sections of sheet piles would be used to 

isolate demolition activities at each of 

the nine in-water piers. Sheet piles for 

cofferdams would be installed with a 

vibratory hammer or a press-in method. 

Up to three cofferdams would be in 

place at any given time. Sheet piles 

would be removed using a vibratory 

hammer or direct pull. 

Barges would be used as platforms to 

perform the demolition and to haul 

materials and equipment to and from 

the work site. Several types and sizes of 

barges are anticipated to be used for 

bridge demolition. The type and size of 

each barge would depend on how the 

barge is used. Up to six stationary or 

moving barges are expected to be 

present at any one time during bridge 

demolition. Over 300 steel pipe piles 

would be used to anchor and support 

the work and material barges necessary 

for demolition. Table 6 summarizes 

temporary pile use during bridge 

demolition. All temporary piles would 

be installed using a vibratory hammer or 

push-in method. They would be 

extracted using vibratory methods or 

direct pull. Piles would be installed and 

removed continuously throughout the 

demolition process. 


tkelley on DSK3SPTVN1PROD with PROPOSALS2
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TABLE 6—SUMMARY OF BARGES AND TEMPORARY PILES USED IN BRIDGE DEMOLITION

Application Locations Barges per 

location Piles per barge Total piles Duration in water (days/location) 

Span removal ......................................... 9 4–6 4 160 30 

Pier demolition ....................................... 9 4 4 144 30 

Total ................................................ .............................. .............................. 304 .............................. ..............................

Equipment required for bridge 

demolition includes barge-mounted 

cranes/hammers or hydraulic rams. 

Vibratory hammers would be used to 

install and remove sheet piles for 

cofferdams and pipe piles for barge 

moorings. New permanent piles would 

not be required for demolition of the 

Columbia River bridges. 

Method of Incidental Taking 

Vibratory and impact pile installation 

and removal, and steel casing 

installation, may result in behavioral 

disturbance, constituting Level B 

harassment. Project construction would 

require the installation and removal of 

approximately 1,500 temporary steel 

piles. In addition to pile and casing 

installation, behavioral disturbance 

could also be caused by increased 

activity and vessel traffic, airborne 

sound from the equipment and human 

work activity, as well as underwater 

sound from debris removal, vessels, and 

physical disturbance. 

Table 7 summarizes the extent, 

timing, and duration of impact pile 

driving. Impact pile driving is expected 

to take place only within a 31-week inwater work window, ranging from 

September 15 to April 15 over the 

bridge construction period. There would 

be a total of about 138 days of impact 

pile driving in the Columbia River and 

about 134 days of impact pile driving in 

North Portland Harbor for the entire 

project from the start of bridge 

construction in 2013 to its anticipated 

completion in 2017 (approximately 4.25 

years for both Columbia River and North 

Portland Harbor Bridges). Impact pile 

driving in the mainstem Columbia River 

would occur at more than one pier 

complex on about 1–2 days total during 

the course of the approximately 4-year 

construction period. Impact pile driving 

would be restricted to approximately 45 

minutes per 12-hour work day. A sound 

attenuation device would generally be 

used for all impact pile driving, with the 

exception of weekly testing of the 

attenuation device, requiring that some 

impact hammering occur with the 

device turned off in order to compare 

produced sound with that produced 

while the device is on. This would 

occur for a maximum of 7.5 minutes per 

week. Each work day would include a 

period of at least 12 consecutive hours 

with no impact pile driving in order to 

minimize disturbance to aquatic 

animals. Impact pile driving would only 

occur during daylight hours. Airborne 

sound effects from impact pile driving 

would occur on the same schedule as 

described in Table 7. 

TABLE 7—SUMMARY OF IMPACT PILE DRIVING

Pile size 

Columbia River North Portland Harbor 

Duration Days Duration Days 

18–24 in (without attenuation device) ............................................. 7.5 min/week ......... 38 2.5–5 min/week ...... 18 

18–24 in (with attenuation device) .................................................. 45 min/day ............. 138 45 min/day ............. 72 

36–48 in (without attenuation device) ............................................. 7.5 min/week ......... 38 2.5–5 min/week ...... 31 

36–48 in (with attenuation device) .................................................. 45 min/day ............. 138 45 min/day ............. 62 

Table 8 summarizes the extent, 

timing, and duration of vibratory 

installation of pipe pile and sheet pile. 

Vibratory installation of pipe pile is 

likely to occur throughout the entire 5- 

year duration of the proposed 

regulations period during construction 

of all new in-water piers or bents and 

for installation of mooring piles. 

Vibratory installation of sheet pile 

would only occur in the Columbia River 

during construction of the new 

Columbia River bridges and demolition 

of the existing Columbia River bridges. 

This activity would occur intermittently 

throughout the construction and 

demolition period. Vibratory activity is 

not restricted to an in-water work 

window, and therefore may take place 

during any time of the year. If steel 

casings for drilled shafts are vibrated 

into place, the CRC project design team 

estimates that installation of the 10-ftdiameter casings would take 

approximately 90 days in the Columbia 

River and 31 days in North Portland 

Harbor. 

TABLE 8—SUMMARY OF VIBRATORY PILE DRIVING

Pile type 

Columbia River North Portland Harbor 

Duration Days Duration Days 

Pipe pile .......................................................................................... Up to 5 hours/day .. 1,470–1,620 Up to 5 hours/day .. 334 

Sheet pile ........................................................................................ Up to 24 hours/day 99 N/A ......................... N/A 

Steel casings ................................................................................... ................................ 90 ................................ 31 

Debris removal is not certain to occur, 

but is included to present the fullest 

disclosure of potential effects. It is 

possible that debris removal would 

occur in North Portland harbor at the 

location of each of the new piers where 


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there is anecdotal evidence that riprap 

occurs within the pier footprints. The 

exact quantity of this material is 

unknown, but as a worst-case scenario 

this activity would remove 

approximately 90 yd3 (69 m3) of 

material over an area of approximately 

2,433 ft2 (226 m2) from all piers 

combined. Debris removal would 

produce sound through use of a bucket 

dredge, for up to 12 hours per day for 

a maximum of 7 days during the 

November 1–February 28 in-water work 

window each year. 

Description of Sound Sources 

Sound travels in waves, the basic 

components of which are frequency, 

wavelength, velocity, and amplitude. 

Frequency is the number of pressure 

waves that pass by a reference point per 

unit of time and is measured in Hz or 

cycles per second. Wavelength is the 

distance between two peaks of a sound 

wave; lower frequency sounds have 

longer wavelengths than higher 

frequency sounds, which is why the 

lower frequency sound associated with 

the proposed activities would attenuate 

more rapidly in shallower water. 

Amplitude is the height of the sound 

pressure wave or the ‘loudness’ of a 

sound and is typically measured using 

the decibel (dB) scale. A dB is the ratio 

between a measured pressure (with 

sound) and a reference pressure (sound 

at a constant pressure, established by 

scientific standards). It is a logarithmic 

unit that accounts for large variations in 

amplitude; therefore, relatively small 

changes in dB ratings correspond to 

large changes in sound pressure. When 

referring to sound pressure levels (SPLs; 

the sound force per unit area), sound is 

referenced in the context of underwater 

sound pressure to 1 microPascal (mPa). 

One pascal is the pressure resulting 

from a force of one newton exerted over 

an area of one square meter. The source 

level represents the sound level at a 

distance of 1 m from the source 

(referenced to 1 mPa). The received level 

is the sound level at the listener’s 

position. 

Root mean square (rms) is the 

quadratic mean sound pressure over the 

duration of an impulse. Rms is 

calculated by squaring all of the sound 

amplitudes, averaging the squares, and 

then taking the square root of the 

average (Urick, 1975). Rms accounts for 

both positive and negative values; 

squaring the pressures makes all values 

positive so that they may be accounted 

for in the summation of pressure levels 

(Hastings and Popper, 2005). This 

measurement is often used in the 

context of discussing behavioral effects, 

in part because behavioral effects, 

which often result from auditory cues, 

may be better expressed through 

averaged units than by peak pressures. 

When underwater objects vibrate or 

activity occurs, sound-pressure waves 

are created. These waves alternately 

compress and decompress the water as 

the sound wave travels. Underwater 

sound waves radiate in all directions 

away from the source (similar to ripples 

on the surface of a pond), except in 

cases where the source is directional. 

The compressions and decompressions 

associated with sound waves are 

detected as changes in pressure by 

aquatic life and man-made sound 

receptors such as hydrophones. 

The underwater acoustic environment 

consists of ambient sound, defined as 

environmental background sound levels 

lacking a single source or point 

(Richardson et al., 1995). The ambient 

underwater sound level of a region is 

defined by the total acoustical energy 

being generated by known and 

unknown sources, including sounds 

from both natural and anthropogenic 

sources. These sources may include 

physical (e.g., waves, earthquakes, ice, 

atmospheric sound), biological (e.g., 

sounds produced by marine mammals, 

fish, and invertebrates), and 

anthropogenic sound (e.g., vessels, 

dredging, aircraft, construction). Known 

sound levels and frequency ranges 

associated with anthropogenic sources 

similar to those that would be used for 

this project are summarized in Table 9. 

Details of each of the sources are 

described in the following text. 

TABLE 9—REPRESENTATIVE SOUND LEVELS OF ANTHROPOGENIC SOURCES

Sound source Frequency range 

(Hz) 

Underwater sound level 

(dB re 1 μPa) Reference 

Small vessels ......................................... 250–1,000 151 dB rms at 1 m ................................ Richardson et al., 1995. 

Tug docking gravel barge ...................... 200–1,000 149 dB rms at 100 m (328 ft) ............... Blackwell and Greene, 2002. 

Vibratory driving of 72-in (1.8 m) steel 

pipe pile.

10–1,500 180 dB rms at 10 m (33 ft) ................... Caltrans, 2007. 

Impact driving of 36-in (0.9 m) steel 

pipe pile.

10–1,500 195 dB rms at 10 m .............................. WSDOT, 2007. 

Impact driving of 66-in (1.7 m) CISS1

piles.

100–1,500 195 dB rms at 10 m .............................. Reviewed in Hastings and Popper, 

2005. 

1 CISS = cast-in-steel-shell. 

The CRC project would produce 

underwater sound through installation 

of piles for temporary in-water work 

platforms and temporary barge 

moorings, and vibratory installation of 

steel casings for drilled shafts. Piles 

would be installed by using impact and/ 

or vibratory hammers, or by press-in 

techniques that do not produce notable 

underwater sound. 

Several types of impact hammers are 

commonly used to install in-water piles: 

air-driven, steam-driven, diesel-driven, 

and hydraulic. Impact hammers operate 

by repeatedly dropping a heavy piston 

onto a pile to drive the pile into the 

substrate. Sound generated by impact 

hammers is characterized by rapid rise 

times and high peak levels, a potentially 

injurious combination (Hastings and 

Popper, 2005). Table 10 summarizes 

observed underwater sound levels 

generated by driving various types and 

sizes of piles. Sound generated by 

impact pile driving is highly variable, 

based on site-specific conditions such as 

substrate, water depth, and current. 

Sound levels may also vary based on the 

size of the pile, the type of pile, and the 

energy of the hammer. 

TABLE 10—SUMMARY OF OBSERVED UNDERWATER SOUND LEVELS GENERATED BY IMPACT PILE DRIVING

Pile size, in (m) Driver type dB Peak dB rms 

12 (0.3) .............................................................................. Impact ............................................................................... 208 191 


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TABLE 10—SUMMARY OF OBSERVED UNDERWATER SOUND LEVELS GENERATED BY IMPACT PILE DRIVING—Continued 

Pile size, in (m) Driver type dB Peak dB rms 

14 (0.4) .............................................................................. Impact ............................................................................... 1 195 1 180 

16 (0.4) .............................................................................. Impact ............................................................................... 2 200 2 187 

24 (0.6) .............................................................................. Impact ............................................................................... 212 189 

30 (0.8) .............................................................................. Impact ............................................................................... 212 195 

36 (0.9) .............................................................................. Impact ............................................................................... 214 201 

60 (1.5) .............................................................................. Impact ............................................................................... 210 195 

66 (1.7) .............................................................................. Impact ............................................................................... 210 195 

96 (2.4) .............................................................................. Impact ............................................................................... 220 205 

126 (3.2) ............................................................................ Impact ............................................................................... 3 213 3 202 

150 (3.8) ............................................................................ Impact ............................................................................... 4 200 4 185 

12 ...................................................................................... Vibratory ........................................................................... 171 155 

24 (sheet), typical ............................................................. Vibratory ........................................................................... 175 160 

24 (sheet), loudest ............................................................ Vibratory ........................................................................... 182 165 

36 (typical) ........................................................................ Vibratory ........................................................................... 180 170 

36 (loudest) ....................................................................... Vibratory ........................................................................... 185 175 

72 (typical) (1.8) ................................................................ Vibratory ........................................................................... 183 170 

72 (loudest) ....................................................................... Vibratory ........................................................................... 195 180 

Source: Caltrans, 2009 

Note: Sound levels measured at a distance of 10 m except where indicated by the following footnotes: 1 30 m; 2 9 m; 3 11 m; 4 100 m. 

Vibratory hammers install piles by 

vibrating them and allowing the weight 

of the hammer to push them into the 

sediment. Vibratory hammers produce 

much less sound than impact hammers. 

Peak SPLs may be 180 dB or greater, but 

are generally 10 to 20 dB lower than 

SPLs generated during impact pile 

driving of the same-sized pile (Caltrans, 

2009). Rise time is slower, reducing the 

probability and severity of injury 

(USFWS, 2009), and sound energy is 

distributed over a greater amount of 

time (Nedwell and Edwards, 2002; 

Carlson et al., 2001). 

Vibratory hammers cannot be used in 

all circumstances. In some substrates, 

the capacity of a vibratory hammer may 

be insufficient to drive the pile to loadbearing capacity or depth (Caltrans, 

2009). Additionally, some vibrated piles 

must be ‘proofed’ (i.e., struck with an 

impact hammer) for several seconds to 

several minutes in order to verify the 

load-bearing capacity of the pile 

(WSDOT, 2008). 

Table 10 outlines typical sound levels 

produced by installation of various 

types of pile using a vibratory pile 

driver. Note that peak sound levels 

range from 171 to 195 dB, whereas peak 

sound levels generated by impact pile 

driving range from 195 to 220 dB. 

Impact and vibratory pile driving are 

the primary in-water construction 

activities associated with the project. 

The sounds produced by these activities 

fall into one of two sound types: pulsed 

and non-pulsed (defined in next 

paragraph). Impact pile driving 

produces pulsed sounds, while 

vibratory pile driving produces nonpulsed sounds. The distinction between 

these two general sound types is 

important because they have differing 

potential to cause physical effects, 

particularly with regard to hearing (e.g., 

Ward, 1997 in Southall et al., 2007). 

Please see Southall et al. (2007) for an 

in-depth discussion of these concepts. 

Pulsed sounds (e.g., explosions, 

gunshots, sonic booms, seismic pile 

driving pulses, and impact pile driving) 

are brief, broadband, atonal transients 

(ANSI, 1986; Harris, 1998) and occur 

either as isolated events or repeated in 

some succession. Pulsed sounds are all 

characterized by a relatively rapid rise 

from ambient pressure to a maximal 

pressure value followed by a decay 

period that may include a period of 

diminishing, oscillating maximal and 

minimal pressures. Pulsed sounds 

generally have an increased capacity to 

induce physical injury as compared 

with sounds that lack these features. 

Non-pulsed sounds (which may be 

intermittent or continuous) can be tonal, 

broadband, or both. Some of these nonpulse sounds can be transient signals of 

short duration but without the essential 

properties of pulses (e.g., rapid rise 

time). Examples of non-pulse sounds 

include those produced by vessels, 

aircraft, machinery operations such as 

drilling or dredging, vibratory pile 

driving, and active sonar systems. The 

duration of such sounds, as received at 

a distance, can be greatly extended in a 

highly reverberant environment. 

Sound Attenuation Devices 

Sound levels can be greatly reduced 

during impact pile driving using sound 

attenuation devices. There are several 

types of sound attenuation devices 

including bubble curtains, cofferdams, 

and isolation casings. Three types of 

attenuation devices are described here. 

Bubble curtains create a column of air 

bubbles rising around a pile from the 

substrate to the water surface. The air 

bubbles absorb and scatter sound waves 

emanating from the pile, thereby 

reducing the sound energy. Bubble 

curtains may be confined or unconfined. 

An unconfined bubble curtain may 

consist of a ring seated on the substrate 

and emitting air bubbles from the 

bottom. An unconfined bubble curtain 

may also consist of a stacked system, 

that is, a series of multiple rings placed 

at the bottom and at various elevations 

around the pile. Stacked systems may be 

more effective than non-stacked systems 

in areas with high current and deep 

water (Caltrans, 2009). 

A confined bubble curtain contains 

the air bubbles within a flexible or rigid 

sleeve made from plastic, cloth, or pipe. 

Confined bubble curtains generally offer 

higher attenuation levels than 

unconfined curtains because they may 

physically block sound waves and they 

prevent air bubbles from migrating away 

from the pile. For this reason, the 

confined bubble curtain is commonly 

used in areas with high current velocity 

(Caltrans, 2009). In Oregon, confined 

bubble curtains are typically required 

where current velocity is 0.6 m/s or 

greater (NMFS, 2008a). 

Cofferdams are often used during 

construction for isolating the in-water 

work area, but may also be used as a 

sound attenuation device. Dewatered 

cofferdams may provide the highest 

levels of sound reduction of any 

attenuation device; however, they do 

not eliminate underwater sound because 

sound can be transmitted through the 

substrate (Caltrans, 2009). Cofferdams 

that are not dewatered provide very 

limited reduction in sound levels. 


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An isolation casing is a hollow pipe 

that surrounds the pile, isolating it from 

the in-water work area. The casing is 

dewatered before pile driving. This 

device provides levels of sound 

attenuation similar to that of bubble 

curtains; however, attenuation rates are 

not as great as those achieved by 

cofferdams because the dewatered area 

between the pile and the water column 

is generally much smaller (Caltrans, 

2009). 

Both environmental conditions and 

the characteristics of the sound 

attenuation device may influence the 

effectiveness of the device. According to 

Caltrans (2009): 

• In general, confined bubble curtains 

attain better sound attenuation levels in 

areas of high current than unconfined 

bubble curtains. If an unconfined device 

is used, high current velocity may 

sweep bubbles away from the pile, 

resulting in reduced levels of sound 

attenuation. 

• Softer substrates may allow for a 

better seal for the device, preventing 

leakage of air bubbles and escape of 

sound waves. This increases the 

effectiveness of the device. Softer 

substrates also provide additional 

attenuation of sound traveling through 

the substrate. 

• Flat bottom topography provides a 

better seal, enhancing effectiveness of 

the sound attenuation device, whereas 

sloped or undulating terrain reduces or 

eliminates its effectiveness. 

• Air bubbles must be close to the 

pile; otherwise, sound may propagate 

into the water, reducing the 

effectiveness of the device. 

• Harder substrates may transmit 

ground-borne sound and propagate it 

into the water column. 

The literature presents a wide array of 

observed attenuation results (see, e.g., 

WSF, 2009; WSDOT, 2008; USFWS, 

2009; Caltrans, 2009). The variability in 

attenuation levels is due to variation in 

design, as well as differences in site 

conditions and difficulty in properly 

installing and operating in-water 

attenuation devices. WSDOT personnel 

have observed that, on average, 

unconfined bubble curtains typically 

achieve 9 dB of attenuation while 

confined bubble curtains achieve 12 dB. 

Caltrans (2009) offers the following 

generalizations: 

• For steel or concrete pile 24 in (0.6 

m) in diameter or less, bubble curtains 

would generally reduce sound levels by 

5 dB. 

• For steel pile measuring 24 to 48 in 

(0.6–1.2 m), bubble curtains may reduce 

sound levels by about 10 dB. 

• For piles greater than 48 in 

diameter, bubble curtains may reduce 

sound levels by about 20 dB. 

• As a general rule, reductions of 

greater than 10 dB cannot be reliably 

predicted. 

Sound Thresholds 

Since 1997, NMFS has used generic 

sound exposure thresholds to determine 

when an activity in the ocean that 

produces sound might result in impacts 

to a marine mammal such that a take by 

harassment or injury might occur 

(NMFS, 2005b). To date, no studies have 

been conducted that examine impacts to 

marine mammals from pile driving 

sounds from which empirical sound 

thresholds have been established. 

Current NMFS practice regarding 

exposure of marine mammals to high 

level sounds is that cetaceans and 

pinnipeds exposed to impulsive sounds 

of 180 and 190 dB rms or above, 

respectively, are considered to have 

been taken by Level A (i.e., injurious) 

harassment. 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-pulsed 

sound (e.g., vibratory pile driving), but 

below injurious thresholds. For airborne 

sound, pinniped disturbance from haulouts has been documented at 100 dB 

(unweighted) for pinnipeds in general, 

and at 90 dB (unweighted) for harbor 

seals. NMFS uses these levels as 

guidelines to estimate when harassment 

may occur. 

Distance to Sound Thresholds 

The extent of project-generated sound 

both in and over water was calculated 

for the locations where pile driving 

would occur in the Columbia River and 

North Portland Harbor. The extent of 

underwater sound was modeled for 

several pile driving scenarios: 

• For two sizes of pile: 18- to 24-in 

(0.5–0.6 m) pile and 36- to 48-in (0.9– 

1.2 m) pile. 

• For single impact pile drivers 

operating both with and without an 

attenuation device. Use of an 

attenuation device was assumed to 

decrease initial SPLs by 10 dB (see 

discussion previously in this 

document). 

• For vibratory driving of pipe pile 

and sheet pile. 

Underwater Sound—Models may be 

used to estimate the distances and areas 

within which sound is likely to exceed 

certain threshold levels. Please note that 

the results of such modeling are 

described here to provide a frame of 

reference for the reader. Actual 

distances and areas within which sound 

is likely to exceed certain threshold 

levels are known from collection of sitespecific hydroacoustic monitoring data 

(see ‘Test Pile Project’, later in this 

document). 

In the absence of site-specific data, 

the practical spreading loss model may 

be used for determining the extent of 

sound from a source (Davidson, 2004; 

Thomsen et al., 2006). The model 

assumes a logarithmic coefficient of 15, 

which equates to sound energy 

decreasing by 4.5 dB with each doubling 

of distance from the source. To calculate 

the loss of sound energy from one 

distance to another, the following 

formula is used: 

Transmission Loss (dB) = 15 log(D1/D0) 

D1 is the distance from the source for 

which SPLs need to be known, and D0

is the distance from the source for 

which SPLs are known (typically 10 m 

from the pile). This model also solves 

for the distance at which sound 

attenuates to various decibel levels (e.g., 

a threshold or background level). The 

following equation solves for distance: 

D1 = D0 × 10(TL/15)

where TL stands for transmission loss 

(the difference in decibel levels between 

D0 and D1). For example, using the 

distance to an injury threshold (D1), the 

area of effect is calculated as the area of 

a circle, pr2, where r (radius) is the 

distance to the threshold or background. 

If a landform or other shadowing 

element interrupts the spread of sound 

within the threshold distance, then the 

area of effect truncates at the location of 

the shadowing element. 

Sound levels are highly dependent on 

environmental site conditions. 

Therefore, published hydroacoustic 

monitoring data for projects with similar 

site conditions as the CRC project were 

considered. WSDOT and the California 

Department of Transportation (Caltrans) 

have compiled hydroacoustic 

monitoring data from in-water impact 

pile driving. No projects with 

hydroacoustic monitoring data and 

similar site conditions were identified 

in the Columbia River. 

A review of WSDOT and Caltrans 

projects containing in-water pile driving 

found projects in California had the 

most similar substrates and depths; 

however, only one project used 48-in 

pile, the largest size in the CRC project. 

This work occurred in the Russian 

River, which was only 15 m wide and 

0.6 m deep at the project location. 

Therefore, the results are not applicable 

to the CRC project. Instead, data from 

projects that drove 36-in pile were used, 

using the highest sound levels 


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encountered as proxy values for 48-in 

pile. 

Maximum measured sound levels 

from 36-in steel pile installation were 

201 dB rms (WSDOT, 2008), as shown 

in Table 10. Site conditions for this 

project, in Puget Sound, are somewhat 

comparable to the Columbia River, as 

both are large, with similar depths. The 

maximum source level from the next 

largest pile size, 60-in (1.5-m) pile, was 

195 dB rms at 10 m. As such, the use 

of data from the 36-in pile 

measurements provides a more 

conservative estimate. The CRC project 

would also drive 18- to 24-in diameter 

steel pile. Conservatively, the highest 

recorded value of 189 dB rms for this 

range of pile sizes was used (see Table 

10). 

No studies were available that 

measured site-specific initial sound 

levels generated by vibratory pile 

driving in the Region of Activity. 

However, Table 10 outlines a range of 

typical sound levels produced by 

vibratory pile driving as measured by 

Caltrans during hydroacoustic 

monitoring of several construction 

projects (Caltrans, 2009). A worst-case 

scenario of installing 48-in steel pipe 

pile (the largest pile size to be used on 

the CRC project) at the loudest 

measured SPLs was considered, 

however, as there were no data for 48- 

in pile, it was assumed that sound levels 

for 48-in pile would be intermediate 

between those levels generated by 36-in 

pile and 72-in (1.8-m) pile. Typical 

values for both 36- and 72-in pile were 

170 dB, while the loudest values were 

175 dB for 36-in pile and 180 dB for 72- 

in pile. Thus, 175 dB was considered an 

appropriate value for initial SPLs for 

vibratory driving of pipe pile. The 

project may also install sheet pile, in the 

Columbia River only. In general, 

installation of sheet pile produces lower 

SPLs than pipe pile. Using data 

presented in Table 10, an initial SPL of 

approximately 160 dB rms at a distance 

of 15 m was assumed. Table 11 shows 

the calculated distances required for 

underwater sound to attenuate to 

relevant thresholds, as per the practical 

spreading model (please see Figures 

B–1 to B–6 of CRC’s application for 

graphical depictions of threshold 

distances discussed here). 

TABLE 11—CALCULATED DISTANCES TO SOUND THRESHOLDS

Threshold Pile size 

Distance to 

threshold 

(without 

attenuation 

device) 

(m) 

Distance to 

threshold 

(with attenuation 

device)* 

(m) 

Injury: 190 dB rms ........................................................ 18–24 in ........................................................................ 9 2 

Harassment: 160 dB rms ............................................. 18–24 in ........................................................................ 858 185 

Injury: 190 dB rms ........................................................ 36–48 in ........................................................................ 54 12 

Harassment: 160 dB rms ............................................. 36–48 in ........................................................................ 5,412 1,166 

Harassment: 120 dB rms ............................................. 36–72 in ........................................................................ 23,208 n/a 

Harassment: 120 dB rms ............................................. 24-in sheet pile ............................................................. 6,962 n/a 

* 10 dB reduction in SPLs assumed from use of attenuation device. 

Landforms in the Columbia River and 

North Portland Harbor would block 

underwater sound well before it reaches 

certain calculated distances. Table 12 

shows actual site-specific values for the 

maximum distance within which sound 

is likely to exceed a given threshold 

level until contact with landforms. 

Categories not listed in Table 12 would 

remain the same as shown in Table 11. 

TABLE 12—ACTUAL DISTANCES TO SOUND THRESHOLDS

Threshold Pile size Location* Upstream 

(m) 

Downstream 

(m) 

Harassment: 160 dB rms .................................... 36–48 in (without attenuation) ........................... NPH 3,058 5,412 

Harassment: 120 dB rms .................................... 36–72 in ............................................................. CR 20,166 8,851 

Harassment: 120 dB rms .................................... 36–72 in ............................................................. NPH 3,058 5,632 

* NPH = North Portland Harbor; CR = Columbia River. 

Airborne Sound—For calculating the 

levels and extent of project-generated 

airborne sound, a point sound source 

and hard-site conditions were assumed 

because pile drivers would be 

stationary, and work would largely 

occur over open water and adjacent to 

an urbanized landscape. Thus, 

calculations assumed that pile driving 

sound would attenuate at a rate of 6 dB 

per doubling distance, based on a 

spherical spreading model. The 

following formula was used to 

determine the distances at which piledriving sound attenuates to the 90 dB 

rms and 100 dB rms (re: 20 mPa; all 

airborne SPLs discussed here are 

referenced to 20 mPa) airborne 

disturbance thresholds: 

D1 = D0 * 10 ((initial SPL¥airborne disturbance

threshold)/

a)

where D1 is the distance from the pile at 

which sound attenuates to the threshold 

value, D0 is the distance from the pile at 

which the initial SPLs were measured, and 

a is the variable for soft-site or hard-site 

conditions. These calculations used a = 20 

for hard-site conditions. 

The estimate of initial sound level is 

based on the results of monitoring 

performed by WSDOT during pile 

driving at Friday Harbor Ferry Terminal 

(Laughlin, 2005b). The results showed 

airborne rms sound levels of 112 dB 

taken at 160 ft (49 m) from the source 

during impact pile driving. This project 

drove 24-in steel pipe pile, which is 

only half the size of the largest pile 

proposed for use in the CRC project. 

However, airborne sound levels are 

independent of the size of the pile (CRC, 

2010), and therefore the sound levels 

encountered at Friday Harbor are 

applicable to the CRC project. 

The model used 112 dB rms at 160 ft 

from the source as the initial sound 

level for a single pile driver. Because 

multiple pile drivers would not strike 


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piles synchronously, operation of 

multiple pile drivers would not generate 

sound louder than that of a single pile 

driver. Therefore, initial sound levels 

for multiple pile drivers were assumed 

to be the same as for a single pile driver. 

The CRC project is not likely to use an 

airborne sound-attenuation device. 

Sound generated by impact pile driving 

in the Columbia River and North 

Portland Harbor is likely to exceed the 

100 dB rms airborne disturbance 

threshold within 195 m of the source 

and is likely to exceed the 90 dB rms 

airborne disturbance threshold within 

650 m of the source. 

Debris Removal—Debris removal may 

occur in North Portland Harbor at the 

location of each of the new piers where 

there is anecdotal evidence that riprap 

occurs within the pier footprints. Debris 

removal in the North Portland Harbor, if 

it occurs, is likely to create sound at or 

above the 120-dB disturbance threshold 

for continuous sound in underwater 

portions of the Region of Activity. 

Few studies have been conducted on 

sound emissions produced by 

underwater debris removal. A review of 

the literature indicates that underwater 

debris removal would produce sound in 

the range of 135 dB to 147 dB at 10 m 

(Dickerson et al., 2001; OSPAR, 2009; 

Thomsen et al., 2009). 

Underwater debris removal is not 

expected to generate significant airborne 

sound. The air-water interface creates a 

substantial sound barrier and reduces 

the intensity of underwater sound 

waves by a factor of more than 1,000 

when they cross the water surface. The 

above-water environment is, thus, 

virtually insulated from the effects of 

underwater sound (Hildebrand, 2005). 

Therefore, underwater debris removal is 

not expected to measurably increase 

ambient airborne sound. Underwater 

sound from debris removal would likely 

attenuate to the 120-dB underwater 

disturbance threshold for continuous 

sound within 631 m of the source. This 

activity would occur for only 7 days, 

during the in-water work window. 

Test Pile Project 

In February 2011, CRC conducted a 

test pile project in order to acquire 

geotechnical and sound propagation 

data to assess site-specific 

characteristics and verify the modeling 

results discussed in the preceding 

section, and to assess mitigation 

measures related to pile installation 

activities planned for the CRC project. 

Please see CRC’s Test Pile 

Hydroacoustic Monitoring Report for 

detailed analysis (SUPPLEMENTARY

INFORMATION). 

Engineering objectives included the 

following: 

• Determine strike numbers necessary 

to install piles to reach load-bearing 

capacity with an impact hammer; 

• Identify suitable equipment and 

materials and verify production rates for 

pile installation; 

• Determine the feasibility of 

vibratory installation methods; and 

• Validate geotechnical and 

engineering calculations. 

Environmental objectives included 

the following: 

• Determine the underwater sound 

levels resulting from vibratory 

installation of temporary piles in the 

predominant substrate types found at 

typical mid-channel depths at the 

project site; 

• Determine the underwater sound 

levels resulting from impact installation 

of temporary piles in the predominant 

substrate types found at typical midchannel depths at the project site; 

• Determine the effectiveness of two 

sound attenuation strategies 

(unconfined and confined bubble 

curtains) during impact pile driving; 

• Determine the transmission loss of 

pile installation sound for both impact 

and vibratory installation; 

• Determine the extent of 

construction sound impacts in-air for 

impact pile driving; and 

• Determine the extent of turbidity 

plumes resulting from vibratory and 

impact pile installation and extraction, 

and from unconfined and confined 

bubble curtain operation. 

Test pile operations consisted of 

impact driving or vibratory driving at 

six pile locations using 24- and 48-in 

piles. A confined or unconfined bubble 

curtain was tested during each pile 

installation. Background sound level 

monitoring was successfully conducted 

between January 27 and February 3, 

2011. The background sound level at 

fifty percent cumulative distribution 

function (CDF) on the Washington 

(north) side of the river was found to be 

110 dB, while the background level at 

fifty percent CDF on the Oregon (south) 

side of the river was slightly higher at 

117 dB. 

Hydroacoustic monitoring was 

successfully conducted during test pile 

construction activities February 11–21, 

2011. Rms pressure levels associated 

with vibratory driving varied widely 

pile to pile; subsurface driving 

conditions are the likely cause of this 

variability. For impact driving, average 

sound levels were derived for both 24- 

in and 48-in piles. Impact driving on 48- 

in piles was, on average, 10 dB louder 

than driving on 24-in piles. 

Measured sound levels for both 

vibratory driving and impact driving 

were similar to those expected as 

outlined previously in this document. 

For vibratory driving, the maximum 

observed sound level was 181 dB, only 

slightly louder than the anticipated 

maximum sound level (180 dB). For 

impact driving, observed unattenuated 

rms sound levels for 24-in piles were 

191 dB, slightly louder than anticipated 

(189 dB). Unattenuated rms sound 

levels for 48-in piles (201 dB) were as 

anticipated. The average rms pressure 

level for vibratory pile extraction was 

173 dB, and did not appear to vary with 

pile size. The 173 dB observed for 

extraction was slightly less than the 176 

dB average observed during pile 

installation. The variance of the 

pressure levels was also less, with 

extraction values ranging from 167–176 

dB while installation values ranged 

from 157–181 dB. 

Open curtain attenuation methods 

reduced the sound levels for 48-in piles 

11 dB on average, and 9 dB on average 

for 24-in piles. Confined curtain 

attenuation methods reduced the sound 

levels for 48-in piles 13 dB on average, 

and 8.5 dB on average for 24-in piles. 

Open bubble curtain attenuation was 

similar to confined curtain attenuation 

at 10 m downstream; however, the 

effectiveness of the open bubble curtain 

appeared to be significantly less 

upstream when compared to 

downstream, likely due to the effect of 

current on the open bubble curtain. The 

observed effectiveness of both open and 

confined bubble curtains at attenuating 

peak amplitudes (8–13 dB) was 

approximately as anticipated (10 dB). 

Transmission loss was analyzed for 

both vibratory driving and impact 

driving. Transmission loss for vibratory 

driving was in line with the practical 

spreading model, as anticipated. 

However, this analysis is based on 

results from only one pile; for two of the 

piles, the signal could not be 

distinguished from background noise at 

200 m, while for a third pile, the signal 

could not be distinguished from 

background noise at 800 m. Thus, 

transmission loss could not be 

calculated for those piles, although 

energy from those piles clearly showed 

rapid attenuation. Transmission loss for 

impact driving was in line with the 

practical spreading model at the 200-m 

range, but steadily increased toward 

spherical spreading with increasing 

range, resulting in greater than 

anticipated transmission loss. 

The data for transmission loss 

associated with vibratory driving 

suggest that the majority of the energy 

occurs in frequencies below 1,000 Hz, 


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with energy levels gradually falling off 

at higher frequencies (CRC, 2011). For 

vibratory installation in this study, 

driving of two piles produced energy 

that could not be distinguished from 

background by 200 m, while the signal 

from a third could not be detected at the 

800 m station. The signal was 

distinguishable from background sound 

levels at approximately 800 m for only 

one of the piles, indicating that distance 

to the threshold would likely be less 

than the modeling results predicted. 

However, background sound levels 

during pile driving were higher than 

those measured previously. It is possible 

that increased background levels 

resulted from sound associated with the 

project, instrumentation, or some other 

source. Nevertheless, data indicate that 

transmission loss for vibratory driving is 

approximately in conformance with 

practical spreading loss. Piles were 

generally installed or extracted during 

the test pile study in less than 5 minutes 

(ranging from less than 1 minute to less 

than 10 minutes, for all but one outlier). 

Measured, site-specific values were 

either substantially similar to assumed 

values or, in the case of transmission 

loss or realized attenuation from use of 

bubble curtains in certain 

circumstances, the assumed values 

described previously in this document 

were more conservative than the actual 

values. As such, those values remain 

valid but likely represent a significantly 

more conservative scenario than would 

realistically occur. Actual distances to 

be monitored for potential injury or 

harassment of pinnipeds would be 

based on the results of in-situ 

hydroacoustic monitoring, where 

relevant, and are discussed in greater 

detail in ‘Proposed Mitigation’, later in 

this document. 

Comments and Responses 

On December 15, 2010, NMFS 

published a notice of receipt of an 

application for a Letter of Authorization 

(LOA) in the Federal Register (75 FR 

78228) and requested comments and 

information from the public for 30 days. 

NMFS did not receive any substantive 

comments. 

Description of Marine Mammals in the 

Area of the Specified Activity 

Marine mammal species that have 

been observed within the Region of 

Activity consist of the harbor seal, 

California sea lion, and Steller sea lion. 

Pinnipeds follow prey species into 

freshwater up to, primarily, the 

Bonneville Dam (RM 145, RKm 233) in 

the Columbia River, but also to 

Willamette Falls in the Willamette River 

(RM 26, RKm 42). The Willamette River 

enters the Columbia River 

approximately 5 mi (8 km) downstream 

of the CRC project area and is within the 

Region of Activity. Harbor seals rarely, 

but occasionally, transit the Region of 

Activity. The eastern population of the 

Steller sea lion is listed as threatened 

under the ESA and as depleted and 

strategic under the MMPA. Neither the 

California sea lion nor the harbor seal is 

listed under the ESA, nor are they 

considered depleted or strategic under 

the MMPA. 

The sea lions use this portion of the 

river primarily for transiting to and from 

Bonneville Dam, which concentrates 

adult salmonids and sturgeon returning 

to natal streams, providing for increased 

foraging efficiency. The U.S. Army 

Corps of Engineers (USACE) has 

conducted surface observations to 

evaluate the seasonal presence, 

abundance, and predation activities of 

pinnipeds in the Bonneville Dam 

tailrace each year since 2002. This 

monitoring program was initiated in 

response to concerns over the potential 

impact of pinniped predation on adult 

salmonids passing Bonneville Dam in 

the spring. An active sea lion hazing, 

trapping, and permanent removal 

program was in place below the dam 

from 2008 through 2010. Much of the 

information presented in this 

application is based on research 

conducted as part of the Bonneville 

Dam sea lion program. 

Pinnipeds remain in upstream 

locations for a couple of days or longer, 

feeding heavily on salmon, steelhead, 

and sturgeon (NOAA 2008), although 

the occurrence of harbor seals near 

Bonneville Dam is much lower than sea 

lions (Stansell et al., 2009). Sea lions 

congregate at Bonneville Dam during 

the peaks of salmon return, from March 

through May each year, and a few 

California sea lions have been observed 

feeding on salmonids in the area below 

Willamette Falls during the spring adult 

fish migration (NOAA, 2008). 

There are no pinniped haul-out sites 

in the Region of Activity. The nearest 

haul-out sites, shared by harbor seals 

and California sea lions, are near the 

Cowlitz River/Carroll Slough confluence 

with the Columbia River, approximately 

45 mi (72 km) downriver from the 

Region of Activity (Jeffries et al., 2000). 

The nearest known haul-out for Steller 

sea lions is a rock formation (Phoca 

Rock) near RM 132 (RKm 212) 

approximately 8 mi (13 km) 

downstream of Bonneville Dam and 26 

mi (42 km) upstream from the Region of 

Activity. Steller sea lions are also 

known to haul out on the south jetty at 

the mouth of the Columbia River, near 

Astoria, Oregon. There are no pinniped 

rookeries located in or near the Region 

of Activity. 

Harbor Seal 

Species Description—Harbor seals, 

which are members of the Phocid family 

(true seals), inhabit coastal and 

estuarine waters and shoreline areas 

from Baja California, Mexico to western 

Alaska. For management purposes, 

differences in mean pupping date (i.e., 

birthing) (Temte, 1986), movement 

patterns (Jeffries, 1985; Brown, 1988), 

pollutant loads (Calambokidis et al., 

1985) and fishery interactions have led 

to the recognition of three separate 

harbor seal stocks along the west coast 

of the continental U.S. (Boveng, 1988). 

The three distinct stocks are: (1) Inland 

waters of Washington (including Hood 

Canal, Puget Sound, and the Strait of 

Juan de Fuca out to Cape Flattery), (2) 

outer coast of Oregon and Washington, 

and (3) California (Carretta et al. 2007b). 

The seals in the Region of Activity are 

from the outer coast of Oregon and 

Washington stock. 

The average weight for adult seals is 

about 180 lb (82 kg) and males are 

typically slightly larger than females. 

Male harbor seals weigh up to 245 lb 

(111 kg) and measure approximately 5 ft 

(1.5 m) in length. The basic color of 

harbor seals’ coat is gray and mottled 

but highly variable, from dark with light 

color rings or spots to light with dark 

markings (NMFS, 2008c). 

Status—In 1999, the population of the 

Oregon/Washington coastal stock of 

harbor seals was estimated at 24,732 

animals (Carretta et al., 2007a). 

Although this abundance estimate 

represents the best scientific 

information available, per NMFS stock 

assessment policy it is not considered 

current because it is more than 8 years 

old. This harbor seal stock includes 

coastal estuaries (Columbia River) and 

bays (Willapa Bay and Grays Harbor). 

Both the Washington and Oregon 

portions of this stock are believed to 

have reached carrying capacity and the 

stock is within its optimum sustainable 

population level (Jeffries et al., 2003; 

Brown et al., 2005). Because there is no 

current estimate of minimum 

abundance, potential biological removal 

(PBR) cannot be calculated for this 

stock. However, the level of humancaused mortality and serious injury is 

less than ten percent of the previous 

PBR of 1,343 harbor seals per year 

(Carretta et al., 2007), and humancaused mortality is considered to be 

small relative to the stock size. 

Therefore, the Oregon and Washington 

outer coast stock of harbor seals are not 

classified as a strategic stock under the 

MMPA. 


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Behavior and Ecology—Harbor seals 

are non-migratory with local movements 

associated with such factors as tides, 

weather, season, food availability, and 

reproduction (Scheffer and Slipp, 1944; 

Fisher, 1952; Bigg, 1969, 1981). They are 

not known to make extensive pelagic 

migrations, although some long distance 

movement of tagged animals in Alaska 

(174 km), and along the U.S. west coast 

(up to 550 km), have been recorded 

(Pitcher and McAllister, 1981; Brown 

and Mate, 1983; Herder, 1986). Harbor 

seals are coastal species, rarely found 

more than 12 mi (20 km) from shore, 

and frequently occupy bays, estuaries, 

and inlets (Baird, 2001). Individual seals 

have been observed several miles 

upstream in coastal rivers. Ideal harbor 

seal habitat includes haul-out sites, 

shelter during the breeding periods, and 

sufficient food (Bjorge, 2002). 

Harbor seals haul out on rocks, reefs, 

beaches, and ice and feed in marine, 

estuarine, and occasionally fresh waters. 

Harbor seals display strong fidelity for 

haul-out sites (Pitcher and Calkins, 

1979; Pitcher and McAllister, 1981), 

although human disturbance can affect 

haul-out choice (Harris et al., 2003). 

Group sizes range from small numbers 

of animals on intertidal rocks to several 

thousand animals found seasonally in 

coastal estuaries. The harbor seal is the 

most commonly observed and widely 

distributed pinniped found in Oregon 

and Washington (Jeffries et al., 2000; 

ODFW, 2010). Harbor seals use 

hundreds of sites to rest or haul out 

along the coast and inland waters of 

Oregon and Washington, including tidal 

sand bars and mudflats in estuaries, 

intertidal rocks and reefs, beaches, log 

booms, docks, and floats in all marine 

areas of the two states. Numerous harbor 

seal haul-out sites are found on 

intertidal mudflats and sand bars from 

the mouth of the lower Columbia River 

to Carroll Slough at the confluence of 

the Cowlitz and Columbia Rivers. 

Harbor seals mate at sea and females 

give birth during the spring and 

summer, although the pupping season 

varies by latitude. Pupping seasons vary 

by geographic region with pups born in 

coastal estuaries (Columbia River, 

Willapa Bay, and Grays Harbor) from 

mid-April through June and in other 

areas along the Olympic Peninsula and 

Puget Sound from May through 

September (WDFW, 2000). Suckling 

harbor seal pups spend as much as forty 

percent of their time in the water 

(Bowen et al., 1999). 

They can be found throughout the 

year at the mouth of the Columbia River. 

Peak harbor seal abundances in the 

Columbia River occur during the winter 

and spring when a number of upriver 

haul-out sites are used. Peak 

abundances and upriver movements in 

the winter and spring months are 

correlated with spawning runs of 

eulachon (Thaleichthys pacificus) smelt 

and out-migration of salmonid smolts. 

Harbor seals are infrequently observed 

at Bonneville Dam or in the Region of 

Activity. In 2009 and again in 2010, two 

harbor seals were observed at the dam 

(Stansell et al., 2009; Stansell and 

Gibbons, 2010), and observations of 

harbor seals at Bonneville Dam have 

ranged from one to three per year from 

2002 to 2010. 

Within the Region of Activity, there 

are no known harbor seal haul-out sites. 

The nearest known haul-out sites to the 

Region of Activity are located at Carroll 

Slough at the confluence of the Cowlitz 

and Columbia Rivers approximately 45 

mi (72 km) downriver of the Region of 

Activity. The low number of 

observations of harbor seals at 

Bonneville Dam over the years, 

combined with the fact that no pupping 

or haul-out locations are within or 

upstream from the Region of Activity, 

suggest that very few harbor seals transit 

through the Region of Activity (Stansell 

et al., 2010). 

Acoustics—In air, harbor seal males 

produce a variety of low-frequency (less 

than 4 kHz) vocalizations, including 

snorts, grunts, and growls. Male harbor 

seals produce communication sounds in 

the frequency range of 100–1,000 Hz 

(Richardson et al., 1995). Pups make 

individually unique calls for mother 

recognition that contain multiple 

harmonics with main energy below 0.35 

kHz (Bigg, 1981; Thomson and 

Richardson, 1995). Harbor seals hear 

nearly as well in air as underwater and 

have lower thresholds than California 

sea lions (Kastak and Schusterman, 

1998). Kastak and Schusterman (1998) 

reported airborne low frequency (100 

Hz) sound detection thresholds at 65 dB 

for harbor seals. In air, they hear 

frequencies from 0.25–30 kHz and are 

most sensitive from 6–16 kHz 

(Richardson, 1995; Terhune and 

Turnbull, 1995; Wolski et al., 2003). 

Adult males also produce underwater 

sounds during the breeding season that 

typically range from 0.25–4 kHz 

(duration range: 0.1 s to multiple 

seconds; Hanggi and Schusterman 

1994). Hanggi and Schusterman (1994) 

found that there is individual variation 

in the dominant frequency range of 

sounds between different males, and 

Van Parijs et al. (2003) reported oceanic, 

regional, population, and site-specific 

variation that could be vocal dialects. In 

water, they hear frequencies from 1–75 

kHz (Southall et al., 2007) and can 

detect sound levels as weak as 60–85 dB 

within that band. They are most 

sensitive at frequencies below 50 kHz; 

above 60 kHz sensitivity rapidly 

decreases. 

California Sea Lions 

Species Description—California sea 

lions are members of the Otariid family 

(eared seals). The species, Zalophus 

californianus, includes three 

subspecies: Z. c. wollebaeki (in the 

Galapagos Islands), Z. c. japonicus (in 

Japan, but now thought to be extinct), 

and Z. c. californianus (found from 

southern Mexico to southwestern 

Canada; referred to here as the 

California sea lion) (Carretta et al., 

2007). The breeding areas of the 

California sea lion are on islands located 

in southern California, western Baja 

California, and the Gulf of California 

(Carretta et al., 2007). These three 

geographic regions are used to separate 

this subspecies into three stocks: (1) The 

U.S. stock begins at the U.S./Mexico 

border and extends northward into 

Canada, (2) the Western Baja California 

stock extends from the U.S./Mexico 

border to the southern tip of the Baja 

California peninsula, and (3) the Gulf of 

California stock which includes the Gulf 

of California from the southern tip of the 

Baja California peninsula and across to 

the mainland and extends to southern 

Mexico (Lowry et al., 1992). 

The California sea lion is sexually 

dimorphic. Males may reach 1,000 lb 

(454 kg) and 8 ft (2.4 m) in length; 

females grow to 300 lb (136 kg) and 

6 ft (1.8 m) in length. Their color ranges 

from chocolate brown in males to a 

lighter, golden brown in females. At 

around 5 years of age, males develop a 

bony bump on top of the skull called a 

sagittal crest. The crest is visible in the 

dog-like profile of male sea lion heads, 

and hair around the crest gets lighter 

with age. 

Status—The U.S. stock of California 

sea lions is estimated at 238,000 and the 

minimum population size of this stock 

is 141,842 individuals (Carretta et al., 

2007). These numbers are from counts 

during the 2001 breeding season of 

animals that were ashore at the four 

major rookeries in southern California 

and at haul-out sites north to the 

Oregon/California border. Sea lions that 

were at-sea or hauled-out at other 

locations were not counted (Carretta et 

al., 2007). The stock has likely reached 

its carrying capacity and, even though 

current total human-caused mortality is 

unknown (due a lack of observer 

coverage in the California set gillnet 

fishery that historically has been the 

largest source of human-caused 

mortalities), California sea lions are not 

considered a strategic stock under the 


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MMPA because total human-caused 

mortality is still likely to be less than 

the PBR. 

Behavior and Ecology—During the 

summer, California sea lions breed on 

islands from the Gulf of California to the 

Channel Islands and seldom travel more 

than about 31 mi (50 km) from the 

islands (Bonnell et al., 1983). The 

primary rookeries are located in the 

California Channel Islands (Le Boeuf 

and Bonnell, 1980; Bonnell and Dailey, 

1993). Their distribution shifts to the 

northwest in fall and to the southeast 

during winter and spring, probably in 

response to changes in prey availability 

(Bonnell and Ford, 1987). 

The non-breeding distribution 

extends from Baja California north to 

Alaska for males, and encompasses the 

waters of California and Baja California 

for females (Reeves et al., 2008; 

Maniscalco et al., 2004). In the nonbreeding season, an estimated 3,000 to 

5,000 adult and sub-adult males migrate 

northward along the coast to central and 

northern California, Oregon, 

Washington, and Vancouver Island from 

September to May (Jeffries et al., 2000) 

and return south the following spring 

(Mate, 1975; Bonnell et al., 1983). 

During migration, they are occasionally 

sighted hundreds of miles offshore 

(Jefferson et al., 1993). Females and 

juveniles tend to stay closer to the 

rookeries (Bonnell et al., 1983). 

California sea lions do not breed in 

Oregon. Though a few young animals 

may remain in Oregon during summer 

months, most return south for the 

breeding season (ODFW, 2010). Male 

California sea lions are commonly seen 

in Oregon from September through May. 

During this time period California sea 

lions can be found in many bays, 

estuaries and on offshore sites along the 

coast, often hauled-out in the same 

locations as Steller sea lions. Some pass 

through Oregon to feed along coastal 

waters to the north during fall and 

winter months (ODFW, 2010). 

California sea lions feed on a wide 

variety of prey, including many species 

of fish and squid (Everitt et al., 1981; 

Roffe and Mate, 1984; Antonelis et al., 

1990; Lowry et al., 1991). In some 

locations where salmon runs exist, 

California sea lions also feed on 

returning adult and out-migrating 

juvenile salmonids (London, 2006). 

Sexual maturity occurs at around 4–5 

years of age for California sea lions 

(Heath, 2002). California sea lions are 

gregarious during the breeding season 

and social on land during other times. 

California sea lions are known to 

occur in several areas of the Columbia 

River during much of the year, except 

the summer breeding months of June 

through August. Approximately 1,000 

California sea lions have been observed 

at haul-out sites at the mouth of the 

Columbia River, while approximately 

100 individuals have been observed in 

past years at the Bonneville Dam 

between January and May prior to 

returning to their breeding rookeries in 

California at the end of May (Stansell, 

2010). The nearest known haul-out sites 

to the Region of Activity are near the 

Cowlitz River/Carroll Slough confluence 

with the Columbia River, approximately 

45 mi (72 km) downriver of the Region 

of Activity (Jeffries et al., 2000). 

The USACE’s intensive sea lion 

monitoring program began as a result of 

the 2000 Federal Columbia River Power 

System (FCRPS) biological opinion, 

which required an evaluation of 

pinniped predation in the tailrace of 

Bonneville Dam. The objective of the 

study was to determine the timing and 

duration of pinniped predation activity, 

estimate the number of fish caught, 

record the number of pinnipeds present, 

identify and track individual California 

sea lions, and evaluate various pinniped 

deterrents used at the dam (Tackley et 

al., 2008a). The study period for 

monitoring was January 1 through May 

31, beginning in 2002. During the study 

period, pinniped observations began 

after consistent sightings of at least one 

animal occurred. Tackley et al. (2008a) 

note that sightings began earlier each 

year from 2002 to 2004. Although some 

sightings were reported earlier in the 

season, full-time observations began 

March 21 in 2002, March 3 in 2003, and 

February 24 in 2004 (Tackley et al., 

2008a). In 2005 observations began in 

April, but in 2006 through 2010 

observations began in January or early 

February (Tackley et al., 2008a, 2008b; 

Stansell et al., 2009; Stansell and 

Gibbons, 2010). In 2009, 54 California 

sea lions were observed at Bonneville 

Dam, the fewest since 2002 (Stansell et 

al., 2009). However, in 2010, 89 

California sea lion individuals were 

observed at Bonneville Dam (Stansell et 

al., 2010). In addition, up to four 

California sea lions have been observed 

at Bonneville Dam during the 

September–January period in recent 

years (CRC, 2010). 

Up to eight California sea lions have 

been observed in recent years feeding on 

salmonids in the Willamette River 

below Willamette Falls (NOAA, 2008). 

The earliest known report of California 

sea lions at Willamette Falls was in 

1975, when two sea lions were reported 

taking salmon and hindering fish 

passage at the fish ladder. Other than 

the 1975 sighting, there were no reports 

of sea lions at Willamette Falls until the 

late 1980s when personnel at the fish 

ladder reported California sea lion 

sightings below the falls. California sea 

lions were sighted sporadically near the 

falls until 1995 when they began 

occurring almost daily from February 

through late May (Scordino, 2010). 

California sea lion arrival and 

departure dates at Bonneville Dam are 

compiled in Table 13 from the reports 

listed in the preceding paragraph. If 

arrival and departure dates were not 

available, the timing of surface 

observations within the January through 

May study period were recorded. 

Because regular observations in the 

study period generally began as 

California sea lions were observed 

below Bonneville Dam, and sometimes 

reports stated that observations stopped 

as sea lion numbers dropped, the 

observation dates only give a general 

idea of first arrival and departure. 

Because tracking data indicate that sea 

lions travel at fast rates between 

hydrophone locations above and below 

the CRC project area, dates of first 

arrival at Bonneville Dam and departure 

from the dam are assumed to coincide 

closely with potential passage timing 

through the CRC project area. 

TABLE 13—ARRIVAL AND DEPARTURE DATES FOR CALIFORNIA SEA LIONS BELOW BONNEVILLE DAM

2002 2003 2004 2005 2006 2007 2008 3 2009 2010 

Arrival ................................................................... 1 3–21 1 3–03 1 2–24 1 4–11/1–21 2–09 1–08 1 1–11 1 1–14 1 1–08 

Departure ............................................................. 1 5–24 1 6–02 1 5–30 1 5–31/6–10 6–02 2 5–26 1 5–31 4 5–19 6–04 

1 Dates are dates observations were taken and not when sea lions were first seen. In 2005 through 2007, observations were made intermittently until sea lions were seen consistently (Tackley et al., 2008a). In 2005, surface observations were made from April 11 through May 31. 

However, the first California sea lion arrived January 21 and departed on June 10 (Tackley et al., 2008a). 2A single sighting was made on November 7 (Tackley et al., 2008a). 3Three California sea lions were observed between September and December 2008. These observations were opportunistic and outside the 

regular observation period of January through May (Stansell et al., 2009). 


tkelley on DSK3SPTVN1PROD with PROPOSALS2
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4Observations ended because few sea lions were present. One California sea lion was in the Bonneville Dam forebay through at least August 

11 (Stansell et al., 2009). 

Based on the information presented in 

Table 13, California sea lions have 

generally been observed at Bonneville 

Dam between early January and early 

June, although beginning in 2008, a few 

individuals have been noted at the dam 

as early as September and as late as 

August. Therefore, the majority of 

California sea lions are expected to pass 

the project site beginning in early 

January through early June. Stansell and 

Gibbons (2010) and Stansell et al. (2009) 

show that California sea lion abundance 

below Bonneville Dam peaks in April, 

when it drops through about the end of 

May. In 2010, California sea lions stayed 

below the dam until almost mid-June, 

which was late historically and enters 

into the time they normally depart for 

southern breeding grounds. Wright et al. 

(2010) reported a median start date for 

the southbound migration from the 

Columbia River to the breeding grounds 

of May 20 (range: May 7 to May 27; 

n = 8 sea lions). 

The highest number of California sea 

lions observed in the Bonneville Dam 

tailrace over the last 9 years was 104 in 

2003 (Stansell et al., 2010). However, 

Tackley et al. (2008a) noted that 

numbers of sea lions estimated from 

early study years were likely 

underestimated, because the observers’ 

ability to uniquely identify individuals 

increased over the years. In addition, 

the high number of 104 individuals 

present below the dam in 2003 occurred 

prior to hazing (2005) or permanent 

removal (2008) activities began. The 

high for the 2008 through 2010 time 

period is a minimum of 89 individuals 

in a year (Stansell et al., 2010). 

The Pacific States Marine Fisheries 

Commission (PSMFC) leads a tagging 

and tracking program for California sea 

lions, observing that the transit time for 

California sea lions between Astoria and 

Bonneville Dam is 30–36 hours 

upstream, and 15 hours downstream 

(CRC, 2010). ODFW studied the 

migration of male California sea lions 

during the nonbreeding season by 

satellite tracking 26 sea lions captured 

in the lower Columbia River over the 

course of three non-breeding seasons 

between November and May in 2003– 

04, 2004–05, and 2006–07. 

Fourteen of the sea lions had 

previously been observed in the 

Columbia River (‘river type’) and twelve 

animals were ‘unknown’ types. Wright 

et al. (2010) found there was 

considerable within and between 

individual variation in spatial and 

temporal movements, which 

presumably reflected variation in 

foraging behavior. Many sea lions 

repeatedly alternated between several 

haul-out sites throughout the nonbreeding season. 

Twenty of the 26 satellite-tagged sea 

lions remained within the waters of 

Oregon and Washington during the time 

they were monitored; the remainder 

made forays north to British Columbia 

or south to California. All fourteen of 

the previously known ‘river’ sea lions 

were later documented upriver (either 

by tracking or direct observation); none 

of the twelve ‘unknown’ animals were 

detected upriver. Southward departure 

dates from the Columbia River ranged 

from May 7 to June 17. Travel time to 

the breeding grounds ranged from 12 to 

21 days. Only one animal was tracked 

back to the Columbia River; it returned 

on August 18 after a 21-day trip from 

San Miguel Island (Wright et al., 2010). 

Movement of sea lions to the base of 

Bonneville Dam to forage on salmonids 

was documented in only a fraction of 

the sea lions tracked, which suggested 

that the problem of pinniped predation 

on Columbia River salmonid stocks 

should be addressed primarily at 

upriver sites such as Bonneville Dam 

rather than in the estuary where sea 

lions of many behavioral types co-occur 

(Wright et al., 2010). 

Acoustics—On land, California sea 

lions make incessant, raucous barking 

sounds; these have most of their energy 

at less than 2 kHz (Schusterman et al., 

1967). Males vary both the number and 

rhythm of their barks depending on the 

social context; the barks appear to 

control the movements and other 

behavior patterns of nearby conspecifics 

(Schusterman, 1977). Females produce 

barks, squeals, belches, and growls in 

the frequency range of 0.25–5 kHz, 

while pups make bleating sounds at 

0.25–6 kHz. California sea lions produce 

two types of underwater sounds: Clicks 

(or short-duration sound pulses) and 

barks (Schusterman et al., 1966, 1967; 

Schusterman and Baillet, 1969). All of 

these underwater sounds have most of 

their energy below 4 kHz (Schusterman 

et al., 1967). 

The range of maximal hearing 

sensitivity for California sea lions 

underwater is between 1–28 kHz 

(Schusterman et al., 1972). Functional 

underwater high frequency hearing 

limits are between 35–40 kHz, with 

peak sensitivities from 15–30 kHz 

(Schusterman et al., 1972). The 

California sea lion shows relatively poor 

hearing at frequencies below 1 kHz 

(Kastak and Schusterman, 1998). Peak 

hearing sensitivities in air are shifted to 

lower frequencies; the effective upper 

hearing limit is approximately 36 kHz 

(Schusterman, 1974). The best range of 

sound detection is from 2–16 kHz 

(Schusterman, 1974). Kastak and 

Schusterman (2002) determined that 

hearing sensitivity generally worsens 

with depth—hearing thresholds were 

lower in shallow water, except at the 

highest frequency tested (35 kHz), 

where this trend was reversed. Octave 

band sound levels of 65–70 dB above 

the animal’s threshold produced an 

average temporary threshold shift (TTS; 

discussed later in POTENTIAL 

EFFECTS OF THE SPECIFIED 

ACTIVITY ON MARINE MAMMALS) of 

4.9 dB in the California sea lion (Kastak 

et al., 1999). 

Steller Sea Lions 

Species Description—Steller sea lions 

are the largest members of the Otariid 

(eared seal) family. Steller sea lions 

show marked sexual dimorphism, in 

which adult males are noticeably larger 

and have distinct coloration patterns 

from females. Males average 

approximately 1,500 lb (680 kg) and 

10 ft (3 m) in length; females average 

about 700 lb (318 kg) and 8 ft (2.4 m) 

in length. Adult females have a tawny 

to silver-colored pelt. Males are 

characterized by dark, dense fur around 

their necks, giving a mane-like 

appearance, and light tawny coloring 

over the rest of their body (NMFS, 

2008a). Steller sea lions are distributed 

mainly around the coasts to the outer 

continental shelf along the North Pacific 

Ocean rim from northern Hokkaido, 

Japan through the Kuril Islands and 

Okhotsk Sea, Aleutian Islands and 

central Bering Sea, southern coast of 

Alaska and south to California. The 

population is divided into the western 

and the eastern distinct population 

segments (DPSs) at 144° W (Cape 

Suckling, Alaska). The western DPS 

includes Steller sea lions that reside in 

the central and western Gulf of Alaska, 

Aleutian Islands, as well as those that 

inhabit coastal waters and breed in Asia 

(e.g., Japan and Russia). The eastern 

DPS extends from California to Alaska, 

including the Gulf of Alaska. 

Status—Steller sea lions were listed 

as threatened range-wide under the ESA 

in 1990. After division into two DPSs, 

the western DPS was listed as 

endangered under the ESA in 1997, 

while the eastern DPS remained 

classified as threatened. Animals found 


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in the Region of Activity are from the 

eastern DPS (NMFS, 1997a; Loughlin, 

2002; Angliss and Outlaw, 2005). The 

eastern DPS breeds in rookeries located 

in southeast Alaska, British Columbia, 

Oregon, and California. While some 

pupping has been reported recently 

along the coast of Washington, there are 

no active rookeries in Washington. A 

final revised species recovery plan 

addresses both DPSs (NMFS, 2008a). 

NMFS designated critical habitat for 

Steller sea lions in 1993. Critical habitat 

is associated with breeding and haul-out 

sites in Alaska, California, and Oregon, 

and includes so-called ‘aquatic zones’ 

that extend 3,000 ft (900 m) seaward in 

state and federally managed waters from 

the baseline or basepoint of each major 

rookery in Oregon and California 

(NMFS, 2008a). Three major rookery 

sites in Oregon (Rogue Reef, Pyramid 

Rock, and Long Brown Rock and Seal 

Rock on Orford Reef at Cape Blanco) 

and three rookery sites in California 

(Ano Nuevo I, Southeast Farallon I, and 

Sugarloaf Island and Cape Mendocino) 

are designated critical habitat (NMFS, 

1993). There is no designated critical 

habitat within the Region of Activity. 

Factors that have previously been 

identified as threats to Steller sea lions 

include reduced food availability, 

possibly resulting from competition 

with commercial fisheries; incidental 

take and intentional kills during 

commercial fish harvests; subsistence 

take; entanglement in marine debris; 

disease; pollution; and harassment. 

Steller sea lions are also sensitive to 

disturbance at rookeries (during 

pupping and breeding) and haul-out 

sites. 

The Recovery Plan for the Steller Sea 

Lion (NMFS, 2008a) states that the 

overall abundance of Steller sea lions in 

the eastern DPS has increased for a 

sustained period of at least three 

decades, and that pup production has 

increased significantly, especially since 

the mid-1990s. Between 1977 and 2002, 

researchers estimated that overall 

abundance of the eastern DPS had 

increased at an average rate of 3.1 

percent per year (NMFS, 2008a; Pitcher 

et al., 2007). NMFS’ most recent stock 

assessment report estimates that 

population for the eastern DPS is a 

minimum of 52,847 individuals; this 

estimate is not corrected for animals at 

sea, and actual population is estimated 

to be within the range 58,334 to 72,223 

(Allen and Angliss, 2010). The 

minimum count for Steller sea lions in 

Oregon and Washington was 5,813 in 

2002 (Pitcher et al., 2007; Allen and 

Angliss, 2010). Counts in Oregon have 

shown a gradual increase from 1,486 

animals in 1976 to 4,169 animals in 

2002 (NMFS, 2008b). 

The abundance of the eastern DPS of 

Steller sea lions is increasing 

throughout the northern portion of its 

range (southeast Alaska and British 

Columbia), and stable or increasing in 

the central portion (Oregon through 

central California). Surveys indicate that 

pup production in Oregon increased at 

3 percent per year from 1990–2009, 

while pup production in California 

increased at 5 percent per year between 

1996 and 2009, with the number of nonpups reported as stable. The best 

available information indicates that, 

overall, the eastern DPS has increased 

from an estimated 18,040 animals in 

1979 to an estimated 63,488 animals in 

2009; therefore the overall estimated 

rate of increase for this period is 4.3 

percent per year (NMML, 2012). 

In the far southern end of Steller sea 

lion range (Channel Islands in southern 

California), population declined 

significantly after the 1930s—probably 

due to hunting and harassment 

(Bartholomew and Boolootian, 1960; 

Bartholomew, 1967)—and several 

rookeries and haul-outs have been 

abandoned. The lack of recolonization 

at the southernmost portion of the range 

(e.g., San Miguel Island rookery), 

despite stability in the non-pup portion 

of the overall California population, is 

likely a response to a suite of factors 

including changes in ocean conditions 

(e.g., warmer temperatures) that may be 

contributing to habitat changes that 

favor California sea lions over Steller 

sea lions (NMFS, 2007) and competition 

for space on land, and possibly prey, 

with species that have experienced 

explosive growth over the past three 

decades (California sea lions and 

northern elephant seals [Mirounga 

angustirostris]). Although recovery in 

California has lagged behind the rest of 

the DPS, this portion of the DPS’ range 

has recently shown a positive growth 

rate (NMML, 2012). While non-pup 

counts in California in the 2000s are 

only 34 percent of pre-decline counts 

(1927–47), the population has increased 

significantly since 1990. 

Despite the abandonment of certain 

rookeries in California, pup production 

at other rookeries in California has 

increased over the last 20 years and, 

overall, the eastern DPS has increased at 

an average annual growth rate of 4.3 

percent per year for 30 years. Even 

though these rookeries might not be 

recolonized, their loss has not prevented 

the increasing abundance of Steller sea 

lions in California or in the eastern DPS 

overall. 

Because the eastern DPS of Steller sea 

lion is currently listed as threatened 

under the ESA, it is therefore designated 

as depleted and classified as a strategic 

stock under the MMPA. However, the 

eastern DPS has been considered a 

potential candidate for removal from 

listing under the ESA by the Steller sea 

lion recovery team and NMFS (NMFS, 

2008), based on observed annual rates of 

increase. Although the stock size has 

increased, the status of this stock 

relative to its Optimum Sustainable 

Population (OSP) size is unknown. The 

overall annual rate of increase of the 

eastern stock has been consistent and 

long-term, and may indicate that this 

stock is reaching OSP. 

Behavior and Ecology—Steller sea 

lions forage near shore and in pelagic 

waters. They are capable of traveling 

long distances in a season and can dive 

to approximately 1,300 ft (400 m) in 

depth. They also use terrestrial habitat 

as haul-out sites for periods of rest, 

molting, and as rookeries for mating and 

pupping during the breeding season. At 

sea, they are often seen alone or in small 

groups, but may gather in large rafts at 

the surface near rookeries and haul-outs. 

Steller sea lions prefer the colder 

temperate to sub-arctic waters of the 

North Pacific Ocean. Haul-outs and 

rookeries usually consist of beaches 

(gravel, rocky or sand), ledges, and 

rocky reefs. In the Bering and Okhotsk 

Seas, sea lions may also haul-out on sea 

ice, but this is considered atypical 

behavior (NOAA, 2010a). 

Steller sea lions are gregarious 

animals that often travel or haul out in 

large groups of up to 45 individuals 

(Keple, 2002). At sea, groups usually 

consist of female and subadult males; 

adult males are usually solitary while at 

sea (Loughlin, 2002). In the Pacific 

Northwest, breeding rookeries are 

located in British Columbia, Oregon, 

and northern California. Steller sea lions 

form large rookeries during late spring 

when adult males arrive and establish 

territories (Pitcher and Calkins, 1981). 

Large males aggressively defend 

territories while non-breeding males 

remain at peripheral sites or haul-outs. 

Females arrive soon after and give birth. 

Most births occur from mid-May 

through mid-July, and breeding takes 

place shortly thereafter. Most pups are 

weaned within a year. Non-breeding 

individuals may not return to rookeries 

during the breeding season but remain 

at other coastal haul-outs (Scordino, 

2006). 

Steller sea lions are opportunistic 

predators, feeding primarily on fish and 

cephalopods, and their diet varies 

geographically and seasonally (Bigg, 

1985; Merrick et al., 1997; Bredesen et 

al., 2006; Guenette et al., 2006). 

Foraging habitat is primarily shallow, 


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nearshore and continental shelf waters; 

freshwater rivers; and also deep waters 

(Reeves et al., 2008; Scordino, 2010). 

In Oregon, Steller sea lions are found 

on offshore rocks and islands. Most of 

these haul-out sites are part of the 

Oregon Islands National Wildlife Refuge 

and are closed to the public (ODFW, 

2010). Oregon is home to the largest 

breeding site in U.S. waters south of 

Alaska, with breeding areas at Three 

Arch Rocks (Oceanside), Orford Reef 

(Port Orford), and Rogue Reef (Gold 

Beach). Steller sea lions are also found 

year-round in smaller numbers at Sea 

Lion Caves and at Cape Arago State 

Park. 

Although Steller sea lions occur 

primarily in coastal habitat in Oregon 

and Washington, they are present yearround in the lower Columbia River, 

usually downstream of the confluence 

of the Cowlitz River (ODFW, 2008). 

However, adult and subadult male 

Steller sea lions have been observed at 

Bonneville Dam, where they prey 

primarily on sturgeon and salmon that 

congregate below the dam. In 2002, the 

USACE began monitoring seasonal 

presence, abundance, and predation 

activities of marine mammals in the 

Bonneville Dam tailrace (Tackley et al., 

2008b). Steller sea lions have been 

documented every year since 2003; 

observations have steadily increased to 

75 Steller sea lions in 2010, the most on 

record and almost triple the number of 

the previous year (26 individuals) 

(Stansell et al., 2009, 2010). 

Steller sea lions use the Columbia 

River for travel, foraging, and resting as 

they move between haul-out sites and 

the dam. There are no known haul-out 

sites within the portions of the Region 

of Activity occurring in the Columbia 

River, Willamette River, or North 

Portland Harbor. The nearest known 

haul-out in the Columbia River is a rock 

formation (Phoca Rock) approximately 

8 mi (13 km) downstream of Bonneville 

Dam (approximately 26 mi (42 km) 

upstream from the project site). Steller 

sea lions are also known to haul out on 

the south jetty at the mouth of the 

Columbia River, near Astoria, Oregon. 

There are no rookeries located in or near 

the Region of Activity. The nearest 

Steller sea lion rookery is on the 

northern Oregon coast at Oceanside 

(ODFW, 2010), approximately 70 mi 

(113 km) south of Astoria, i.e., more 

than 150 mi (240 km) from the Region 

of Activity. 

Steller sea lions arrive at the dam in 

late fall (Tackley et al., 2008b), although 

occasionally individuals are sighted 

near Bonneville Dam in the months of 

September, October, and November 

(Stansell et al., 2009, 2010). Steller sea 

lions are present at the dam through 

May, and can travel between the dam 

and the mouth of the Columbia River 

several times during these months 

(Tackley et al., 2008b). Table 14 

compiles data from surface observations 

by the USACE for the Bonneville Dam 

tailrace. If arrival and departure dates 

were not available, the timing of surface 

observations within the January through 

May study period were recorded. 

Because regular observations in the 

study period generally began when 

California sea lions are observed below 

Bonneville Dam, and sometimes reports 

stated that observations stopped as sea 

lion numbers dropped, the observation 

dates only give a general idea of first 

arrival and departure for Steller sea 

lions. Because tracking data indicate 

that sea lions travel at fast rates between 

hydrophone locations above and below 

the CRC project area (Brown et al., 

2010), dates of first arrival at Bonneville 

Dam and departure from the dam are 

assumed to coincide closely with 

potential passage timing through the 

CRC project area. 

TABLE 14—ARRIVAL AND DEPARTURE DATES FOR STELLER SEA LIONS BELOW BONNEVILLE DAM

2002 2003 2004 2005 2006 2007 2008 2009 2010 

Arrival ............................................. n/a ........ 1 3–03 1 2–24 1 4–11 1,2 2–10 1,2 1–08 1,3 1–11 1,4 1–14 1,6 1–08 

Departure ....................................... n/a ........ 1 6–02 1 5–30 1 5–31 1,2 5–31 1,2 5–26 1 5–31 5 5–19 6–04 

1 Dates are dates observations were taken and not when sea lions were first seen. Observations were made in 2002, but no Steller sea lions 

were observed. In 2005 through 2007, observations were made intermittently until sea lions were seen consistently (Tackley et al., 2008a). Observation dates for 2006–07 from Scordino 2010. 2 In 2006 and 2007 Steller sea lions were seen regularly in the tailrace area from January to early March. Report notes anecdotal information 

on sightings of Steller sea lions in November and December. Report states that after March when hazing activities began, fewer Steller sea lions 

were observed through May (Tackley et al., 2008a). 3Steller sea lions were known to be catching and consuming sturgeon in the Bonneville Dam tailrace and farther downstream as early as November 2007 (Tackley et al., 2008b). 4Steller sea lions were known to be catching and consuming sturgeon in the Bonneville Dam tailrace and farther downstream as early as October 2008 (Stansell et al., 2009). 5Observations ended because few sea lions were present. 

6Steller sea lions were observed downriver of the Bonneville Dam tailrace as early as September 2009 (Stansell et al., 2010). 

Based on the information presented in 

Table 14, Steller sea lions are expected 

to pass the project site beginning with 

a few individuals as early as September 

and most individuals in January through 

early June. Stansell et al. (2009, 2010) 

show that Steller sea lion abundance 

below Bonneville Dam increases 

through approximately mid-April, and 

then drops through about the end of 

May. 

ODFW tagged eight Steller sea lions 

with acoustic and/or satellite-linked 

transmitters from March 30 through 

May 4, 2010 (Wright, 2010a). Data show 

that the eight individuals only made one 

or two roundtrips from Bonneville 

during the months they were tracked. 

This study is ongoing and more 

information will be available in the 

future to determine both the number of 

roundtrips from Bonneville and the time 

to transit between Bonneville and the 

mouth of the Columbia River. Although 

transit times between the mouth of the 

Columbia River and Bonneville Dam are 

not available for Steller sea lions, they 

are available for California sea lions. 

The PSMFC leads a tagging and tracking 

program for California sea lions, which 

has observed that the transit time for 

California sea lions between Astoria and 

Bonneville Dam is 30–36 hours 

upstream and 15 hours downstream 

(CRC, 2010). Similar transit times are 

assumed here for Steller sea lions. 

Steller sea lions have generally been 

observed at Bonneville Dam between 

early January and late May, although 

individuals have been noted at the dam 

as early as September (Stansell et al., 

2010). Thus, Steller sea lions are likely 

to be transiting in the Columbia River 

and North Portland Harbor during the 

time that in-water work would take 

place. 

Acoustics—Like all pinnipeds, the 

Steller sea lion is amphibious; while all 

foraging activity takes place in the 

water, breeding behavior is carried out 

on land in coastal rookeries (Mulsow 


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and Reichmuth 2008). On land, 

territorial male Steller sea lions 

regularly use loud, relatively lowfrequency calls/roars to establish 

breeding territories (Schusterman et al., 

1970; Loughlin et al., 1987). The calls of 

females range from 0.03 to 3 kHz, with 

peak frequencies from 0.15 to 1 kHz; 

typical duration is 1.0 to 1.5 sec 

(Campbell et al., 2002). Pups also 

produce bleating sounds. Individually 

distinct vocalizations exchanged 

between mothers and pups are thought 

to be the main modality by which 

reunion occurs when mothers return to 

crowded rookeries following foraging at 

sea (Mulsow and Reichmuth, 2008). 

Mulsow and Reichmuth (2008) 

measured the unmasked airborne 

hearing sensitivity of one male Steller 

sea lion. The range of best hearing 

sensitivity was between 5 and 14 kHz. 

Maximum sensitivity was found at 10 

kHz, where the subject had a mean 

threshold of 7 dB. The underwater 

hearing threshold of a male Steller sea 

lion was significantly different from that 

of a female. The peak sensitivity range 

for the male was from 1 to 16 kHz, with 

maximum sensitivity (77 dB re: 1mPa-m) 

at 1 kHz. The range of best hearing for 

the female was from 16 to above 25 kHz, 

with maximum sensitivity (73 dB re: 

1mPa-m) at 25 kHz. However, because of 

the small number of animals tested, the 

findings could not be attributed to either 

individual differences in sensitivity or 

sexual dimorphism (Kastelein et al., 

2005). 

Background on Marine Mammal 

Hearing 

When considering the influence of 

various kinds of sound on the marine 

environment, it is necessary to 

understand that different kinds of 

marine life are sensitive to different 

frequencies of sound. Based on available 

behavioral data, audiograms derived 

using auditory evoked potential 

techniques, anatomical modeling, and 

other data, Southall et al. (2007) 

designate functional hearing groups for 

marine mammals and estimate the lower 

and upper frequencies of functional 

hearing of the groups. The functional 

groups and the associated frequencies 

are indicated below (though animals are 

less sensitive to sounds at the outer edge 

of their functional range and most 

sensitive to sounds of frequencies 

within a smaller range somewhere in 

the middle of their functional hearing 

range): 

• Low frequency cetaceans 

(mysticetes): Functional hearing is 

estimated to occur between 

approximately 7 Hz and 22 kHz; 

• Mid-frequency cetaceans (dolphins, 

larger toothed whales, beaked and 

bottlenose whales): Functional hearing 

is estimated to occur between 

approximately 150 Hz and 160 kHz; 

• High frequency cetaceans (true 

porpoises, river dolphins, Kogia sp.): 

Functional hearing is estimated to occur 

between approximately 200 Hz and 180 

kHz; and 

• Pinnipeds in water: functional 

hearing is estimated to occur between 

approximately 75 Hz and 75 kHz, with 

the greatest sensitivity between 

approximately 700 Hz and 20 kHz. 

As mentioned previously in this 

document, three species of pinnipeds 

are likely to occur in the Region of 

Activity. 

Potential Effects of the Specified 

Activity on Marine Mammals 

CRC’s in-water construction and 

demolition activities (e.g., pile driving 

and removal) introduce sound into the 

marine environment, and have the 

potential to have adverse impacts on 

marine mammals. The potential effects 

of sound from the proposed activities 

associated with the CRC project may 

include one or more of the following: 

Tolerance; masking of natural sounds; 

behavioral disturbance; non-auditory 

physical effects; and temporary or 

permanent hearing impairment 

(Richardson et al., 1995). However, for 

reasons discussed later in this 

document, it is unlikely that there 

would be any cases of temporary or 

permanent hearing impairment resulting 

from these activities. As outlined in 

previous NMFS documents, the effects 

of sound on marine mammals are highly 

variable, and can be categorized as 

follows (based on Richardson et al., 

1995): 

• The sound may be too weak to be 

heard at the location of the animal (i.e., 

lower than the prevailing ambient 

sound level, the hearing threshold of the 

animal at relevant frequencies, or both); 

• The sound may be audible but not 

strong enough to elicit any overt 

behavioral response; 

• The sound may elicit reactions of 

varying degrees and variable relevance 

to the well being of the marine mammal; 

these can range from temporary alert 

responses to active avoidance reactions 

such as vacating an area until the 

stimulus ceases, but potentially for 

longer periods of time; 

• Upon repeated exposure, a marine 

mammal may exhibit diminishing 

responsiveness (habituation), or 

disturbance effects may persist; the 

latter is most likely with sounds that are 

highly variable in characteristics and 

unpredictable in occurrence, and 

associated with situations that a marine 

mammal perceives as a threat; 

• Any anthropogenic sound that is 

strong enough to be heard has the 

potential to result in masking, or reduce 

the ability of a marine mammal to hear 

biological sounds at similar frequencies, 

including calls from conspecifics and 

underwater environmental sounds such 

as surf sound; 

• If mammals remain in an area 

because it is important for feeding, 

breeding, or some other biologically 

important purpose even though there is 

chronic exposure to sound, it is possible 

that there could be sound-induced 

physiological stress; this might in turn 

have negative effects on the well-being 

or reproduction of the animals involved; 

and 

• Very strong sounds have the 

potential to cause a temporary or 

permanent reduction in hearing 

sensitivity, also referred to as threshold 

shift. In terrestrial mammals, and 

presumably marine mammals, received 

sound levels must far exceed the 

animal’s hearing threshold for there to 

be any temporary threshold shift (TTS). 

For transient sounds, the sound level 

necessary to cause TTS is inversely 

related to the duration of the sound. 

Received sound levels must be even 

higher for there to be risk of permanent 

hearing impairment (PTS). In addition, 

intense acoustic or explosive events 

may cause trauma to tissues associated 

with organs vital for hearing, sound 

production, respiration and other 

functions. This trauma may include 

minor to severe hemorrhage. 

Tolerance 

Numerous studies have shown that 

underwater sounds from industrial 

activities are often readily detectable by 

marine mammals in the water at 

distances of many kilometers. However, 

other studies have shown that marine 

mammals at distances more than a few 

kilometers away often show no apparent 

response to industrial activities of 

various types (Miller et al., 2005). This 

is often true even in cases when the 

sounds must be readily audible to the 

animals based on measured received 

levels and the hearing sensitivity of that 

mammal group. Although various 

baleen whales, toothed whales, and (less 

frequently) pinnipeds have been shown 

to react behaviorally to underwater 

sound from sources such as airgun 

pulses or vessels under some 

conditions, at other times, mammals of 

all three types have shown no overt 

reactions (e.g., Malme et al., 1986; 

Richardson et al., 1995; Madsen and 

Mohl, 2000; Croll et al., 2001; Jacobs 

and Terhune, 2002; Madsen et al., 2002; 


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Miller et al., 2005). In general, 

pinnipeds seem to be more tolerant of 

exposure to some types of underwater 

sound than are baleen whales. 

Richardson et al. (1995) found that 

vessel sound does not seem to strongly 

affect pinnipeds that are already in the 

water. Richardson et al. (1995) went on 

to explain that seals on haul-outs 

sometimes respond strongly to the 

presence of vessels and at other times 

appear to show considerable tolerance 

of vessels, and Brueggeman et al. (1992) 

observed ringed seals (Pusa hispida) 

hauled out on ice pans displaying shortterm escape reactions when a ship 

approached within 0.16–0.31 mi (0.25– 

0.5 km). 

Masking 

Masking is the obscuring of sounds of 

interest to an animal by other sounds, 

typically at similar frequencies. Marine 

mammals are highly dependent on 

sound, and their ability to recognize 

sound signals amid other sound is 

important in communication and 

detection of both predators and prey. 

Background ambient sound may 

interfere with or mask the ability of an 

animal to detect a sound signal even 

when that signal is above its absolute 

hearing threshold. Even in the absence 

of anthropogenic sound, the marine 

environment is often loud. Natural 

ambient sound includes contributions 

from wind, waves, precipitation, other 

animals, and (at frequencies above 30 

kHz) thermal sound resulting from 

molecular agitation (Richardson et al., 

1995). 

Background sound may also include 

anthropogenic sound, and masking of 

natural sounds can result when human 

activities produce high levels of 

background sound. Conversely, if the 

background level of underwater sound 

is high (e.g., on a day with strong wind 

and high waves), an anthropogenic 

sound source would not be detectable as 

far away as would be possible under 

quieter conditions and would itself be 

masked. Ambient sound is highly 

variable on continental shelves 

(Thompson, 1965; Myrberg, 1978; 

Chapman et al., 1998; Desharnais et al., 

1999). This results in a high degree of 

variability in the range at which marine 

mammals can detect anthropogenic 

sounds. 

Although masking is a phenomenon 

which may occur naturally, the 

introduction of loud anthropogenic 

sounds into the marine environment at 

frequencies important to marine 

mammals increases the severity and 

frequency of occurrence of masking. For 

example, if a baleen whale is exposed to 

continuous low-frequency sound from 

an industrial source, this would reduce 

the size of the area around that whale 

within which it can hear the calls of 

another whale. The components of 

background noise that are similar in 

frequency to the signal in question 

primarily determine the degree of 

masking of that signal. In general, little 

is known about the degree to which 

marine mammals rely upon detection of 

sounds from conspecifics, predators, 

prey, or other natural sources. In the 

absence of specific information about 

the importance of detecting these 

natural sounds, it is not possible to 

predict the impact of masking on marine 

mammals (Richardson et al., 1995). In 

general, masking effects are expected to 

be less severe when sounds are transient 

than when they are continuous. 

Masking is typically of greater concern 

for those marine mammals that utilize 

low frequency communications, such as 

baleen whales and, as such, is not likely 

to occur for pinnipeds in the Region of 

Activity. 

Disturbance 

Behavioral disturbance is one of the 

primary potential impacts of 

anthropogenic sound on marine 

mammals. Disturbance can result in a 

variety of effects, such as subtle or 

dramatic changes in behavior or 

displacement, but the degree to which 

disturbance causes such effects may be 

highly dependent upon the context in 

which the stimulus occurs. For 

example, an animal that is feeding may 

be less prone to disturbance from a 

given stimulus than one that is not. For 

many species and situations, there is no 

detailed information about reactions to 

sound. 

Behavioral reactions of marine 

mammals to sound are difficult to 

predict because they are dependent on 

numerous factors, including species, 

maturity, experience, activity, 

reproductive state, time of day, and 

weather. If a marine mammal does react 

to an underwater sound by changing its 

behavior or moving a small distance, the 

impacts of that change may not be 

important to the individual, the stock, 

or the species as a whole. However, if 

a sound source displaces marine 

mammals from an important feeding or 

breeding area for a prolonged period, 

impacts on the animals could be 

important. In general, pinnipeds seem 

more tolerant of, or at least habituate 

more quickly to, potentially disturbing 

underwater sound than do cetaceans, 

and generally seem to be less responsive 

to exposure to industrial sound than 

most cetaceans. Pinniped responses to 

underwater sound from some types of 

industrial activities such as seismic 

exploration appear to be temporary and 

localized (Harris et al., 2001; Reiser et 

al., 2009). 

Because the few available studies 

show wide variation in response to 

underwater and airborne sound, it is 

difficult to quantify exactly how pile 

driving sound would affect pinnipeds. 

The literature shows that elevated 

underwater sound levels could prompt 

a range of effects, including no obvious 

visible response, or behavioral 

responses that may include annoyance 

and increased alertness, visual 

orientation towards the sound, 

investigation of the sound, change in 

movement pattern or direction, 

habituation, alteration of feeding and 

social interaction, or temporary or 

permanent avoidance of the area 

affected by sound. Minor behavioral 

responses do not necessarily cause longterm effects to the individuals involved. 

Severe responses include panic, 

immediate movement away from the 

sound, and stampeding, which could 

potentially lead to injury or mortality 

(Southall et al., 2007). 

Southall et al. (2007) reviewed 

literature describing responses of 

pinnipeds to non-pulsed sound in water 

and reported that the limited data 

suggest exposures between 

approximately 90 and 140 dB generally 

do not appear to induce strong 

behavioral responses in pinnipeds, 

while higher levels of pulsed sound, 

ranging between 150 and 180 dB, will 

prompt avoidance of an area. It is 

important to note that among these 

studies, there are some apparent 

differences in responses between field 

and laboratory conditions. In contrast to 

the mid-frequency odontocetes, captive 

pinnipeds responded more strongly at 

lower levels than did animals in the 

field. Again, contextual issues are the 

likely cause of this difference. For 

airborne sound, Southall et al. (2007) 

note there are extremely limited data 

suggesting very minor, if any, 

observable behavioral responses by 

pinnipeds exposed to airborne pulses of 

60 to 80 dB; however, given the paucity 

of data on the subject, we cannot rule 

out the possibility that avoidance of 

sound in the Region of Activity could 

occur. 

In their comprehensive review of 

available literature, Southall et al. 

(2007) noted that quantitative studies on 

behavioral reactions of pinnipeds to 

underwater sound are rare. A subset of 

only three studies observed the response 

of pinnipeds to multiple pulses of 

underwater sound (a category of sound 

types that includes impact pile driving), 

and were also deemed by the authors as 

having results that are both measurable 


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and representative. However, a number 

of studies not used by Southall et al. 

(2007) provide additional information, 

both quantitative and anecdotal, 

regarding the reactions of pinnipeds to 

multiple pulses of underwater sound. 

• Harris et al. (2001) observed the 

response of ringed, bearded (Erignathus 

barbatus), and spotted seals (Phoca 

largha) to underwater operation of a 

single air gun and an eleven-gun array. 

Received exposure levels were 160 to 

200 dB. Results fit into two categories. 

In some instances, seals exhibited no 

response to sound. However, the study 

noted significantly fewer seals during 

operation of the full array in some 

instances. Additionally, the study noted 

some avoidance of the area within 

150 m of the source during full array 

operations. 

• Blackwell et al. (2004) is the only 

cited study directly related to pile 

driving. The study observed ringed seals 

during impact installation of steel pipe 

pile. Received underwater SPLs were 

measured at 151 dB at 63 m. The seals 

exhibited either no response or only 

brief orientation response (defined as 

‘‘investigation or visual orientation’’). It 

should be noted that the observations 

were made after pile driving was 

already in progress. Therefore, it is 

possible that the low-level response was 

due to prior habituation. 

• Miller et al. (2005) observed 

responses of ringed and bearded seals to 

a seismic air gun array. Received 

underwater sound levels were estimated 

at 160 to 200 dB. There were fewer seals 

present close to the sound source during 

air gun operations in the first year, but 

in the second year the seals showed no 

avoidance. In some instances, seals were 

present in very close range of the sound. 

The authors concluded that there was 

‘‘no observable behavioral response’’ to 

seismic air gun operations. 

During a Caltrans installation 

demonstration project for retrofit work 

on the East Span of the San Francisco 

Oakland Bay Bridge, California, sea 

lions responded to pile driving by 

swimming rapidly out of the area, 

regardless of the size of the pile-driving 

hammer or the presence of sound 

attenuation devices (74 FR 63724). 

Jacobs and Terhune (2002) observed 

harbor seal reactions to acoustic 

harassment devices (AHDs) with source 

level of 172 dB deployed around 

aquaculture sites. Seals were generally 

unresponsive to sounds from the AHDs. 

During two specific events, individuals 

came within 141 and 144 ft (43 and 

44 m) of active AHDs and failed to 

demonstrate any measurable behavioral 

response; estimated received levels 

based on the measures given were 

approximately 120 to 130 dB. 

Costa et al. (2003) measured received 

sound levels from an Acoustic 

Thermometry of Ocean Climate (ATOC) 

program sound source off northern 

California using acoustic data loggers 

placed on translocated elephant seals. 

Subjects were captured on land, 

transported to sea, instrumented with 

archival acoustic tags, and released such 

that their transit would lead them near 

an active ATOC source (at 0.6 mi depth 

[939 m]; 75-Hz signal with 37.5-Hz 

bandwidth; 195 dB maximum source 

level, ramped up from 165 dB over 20 

min) on their return to a haul-out site. 

Received exposure levels of the ATOC 

source for experimental subjects 

averaged 128 dB (range 118 to 137) in 

the 60- to 90-Hz band. None of the 

instrumented animals terminated dives 

or radically altered behavior upon 

exposure, but some statistically 

significant changes in diving parameters 

were documented in nine individuals. 

Translocated northern elephant seals 

exposed to this particular non-pulse 

source began to demonstrate subtle 

behavioral changes at exposure to 

received levels of approximately 120 to 

140 dB. 

Several available studies provide 

information on the reactions of 

pinnipeds to non-pulsed underwater 

sound. Kastelein et al. (2006) exposed 

nine captive harbor seals in an 

approximately 82 x 98 ft (25 x 30 m) 

enclosure to non-pulse sounds used in 

underwater data communication 

systems (similar to acoustic modems). 

Test signals were frequency modulated 

tones, sweeps, and bands of sound with 

fundamental frequencies between 8 and 

16 kHz; 128 to 130 ±3 dB source levels; 

1- to 2-s duration (60–80 percent duty 

cycle); or 100 percent duty cycle. They 

recorded seal positions and the mean 

number of individual surfacing 

behaviors during control periods (no 

exposure), before exposure, and in 

15-min experimental sessions (n = 7 

exposures for each sound type). Seals 

generally swam away from each source 

at received levels of approximately 107 

dB, avoiding it by approximately 16 ft 

(5 m), although they did not haul out of 

the water or change surfacing behavior. 

Seal reactions did not appear to wane 

over repeated exposure (i.e., there was 

no obvious habituation), and the colony 

of seals generally returned to baseline 

conditions following exposure. The 

seals were not reinforced with food for 

remaining in the sound field. 

Reactions of harbor seals to the 

simulated sound of a 2-megawatt wind 

power generator were measured by 

Koschinski et al. (2003). Harbor seals 

surfaced significantly further away from 

the sound source when it was active and 

did not approach the sound source as 

closely. The device used in that study 

produced sounds in the frequency range 

of 30 to 800 Hz, with peak source levels 

of 128 dB at 1 m at the 80- and 160-Hz 

frequencies. 

Ship and boat sound do not seem to 

have strong effects on seals in the water, 

but the data are limited. When in the 

water, seals appear to be much less 

apprehensive about approaching 

vessels. Some would approach a vessel 

out of apparent curiosity, including 

noisy vessels such as those operating 

seismic airgun arrays (Moulton and 

Lawson, 2002). Gray seals (Halichoerus 

grypus) have been known to approach 

and follow fishing vessels in an effort to 

steal catch or the bait from traps. In 

contrast, seals hauled out on land often 

are quite responsive to nearby vessels. 

Terhune (1985) reported that northwest 

Atlantic harbor seals were extremely 

vigilant when hauled out and were wary 

of approaching (but less so passing) 

boats. Suryan and Harvey (1999) 

reported that Pacific harbor seals 

commonly left the shore when 

powerboat operators approached to 

observe the seals. Those seals detected 

a powerboat at a mean distance of 866 

ft (264 m), and seals left the haul-out 

site when boats approached to within 

472 ft (144 m). 

Southall et al. (2007) also compiled 

known studies of behavioral responses 

of marine mammals to airborne sound, 

noting that studies of pinniped response 

to airborne pulsed sounds are 

exceedingly rare. The authors deemed 

only one study as having quantifiable 

results. 

• Blackwell et al. (2004) studied the 

response of ringed seals within 500 m 

of impact driving of steel pipe pile. 

Received levels of airborne sound were 

measured at 93 dB at a distance of 

63 m. Seals had either no response or 

limited response to pile driving. 

Reactions were described as 

‘‘indifferent’’ or ‘‘curious.’’ 

Efforts to deter pinniped predation on 

salmonids below Bonneville Dam began 

in 2005, and have used Acoustic 

Deterrent Devices (ADDs), boat chasing, 

above-water pyrotechnics (cracker 

shells, screamer shells or rockets), 

rubber bullets, rubber buckshot, and 

beanbags (Stansell et al., 2009). Review 

of deterrence activities by the West 

Coast Pinniped Program noted ‘‘USACE 

observations from 2002 to 2008 

indicated that increasing numbers of 

California sea lions were foraging on 

salmon at Bonneville Dam each year, 

salmon predation rates increased, and 

the deterrence efforts were having little 


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effect on preventing predation’’ 

(Scordino, 2010). In the USACE status 

report through May 28, 2010, boat 

hazing was reported to have limited, 

local, short term impact in reducing 

predation in the tailrace, primarily from 

Steller sea lions. ODFW and the WDFW 

reported that sea lion presence did not 

appear to be significantly influenced by 

boat-based activities and several ‘‘new’’ 

sea lions (initially unbranded or 

unknown from natural markings) 

continued to forage in the observation 

area in spite of shore- and boat-based 

hazing. They suggested that hazing was 

not effective at deterring naive sea lions 

if there were large numbers of 

experienced sea lions foraging in the 

area (Brown et al., 2010). Observations 

on the effect of ADDs, which were 

installed at main fishway entrances in 

2007, noted that pinnipeds were 

observed swimming and eating fish 

within 20 ft (6 m) of some of the devices 

with no deterrent effect observed 

(Tackley et al., 2008a, 2008b; Stansell et 

al., 2009, 2010). Many of the animals 

returned to the area below the dam 

despite hazing efforts (Stansell et al., 

2009, Stansell and Gibbons, 2010). 

Relocation efforts to Astoria and the 

Oregon coast were implemented in 

2007; however, all but one of fourteen 

relocated animals returned to 

Bonneville Dam within days (Scordino, 

2010). 

No information on in-water sound 

levels of hazing activities at Bonneville 

Dam has been published other than that 

ADDs produce underwater sound levels 

of 205 dB in the 15 kHz range (Stansell 

et al., 2009). Durations of boat-based 

hazing events were reported at less than 

30 minutes for most of the 521 boatbased events in 2009, but ranged up to 

90 minutes (Brown et al., 2009). 

Durations of boat-based hazing events 

were not reported for 2010. However, 

280 events occurred over 44 days during 

a five-month period using a total of 

4,921 cracker shells, 777 seal bombs, 

and 97 rubber buckshot rounds (Brown 

et al., 2010). Based on knowledge of inwater sound from construction 

activities, the CRC project believes that 

sound levels from in-water construction 

and demolition activities that pinnipeds 

would be potentially exposed to are not 

as high as those produced by hazing 

techniques. 

In addition, sea lions are expected to 

quickly traverse through and not remain 

in the project area. Tagging studies of 

California sea lions indicate that they 

pass hydrophones upriver and 

downriver of the CRC project site 

quickly. Wright et al. (2010) reported 

minimum upstream and downstream 

transit times between the Astoria haulout and Bonneville Dam (river distance 

approximately 20 km) were 1.9 and 

1 day, respectively, based on fourteen 

trips by eleven sea lions. The transit 

speed was calculated to be 4.6 km/hr in 

the upstream direction and 8.8 km/hr in 

the downstream direction. Data from the 

six individuals acoustically tagged in 

2009 show that they made a combined 

total of eleven upriver or downriver 

trips quickly through the CRC project 

site to or from Bonneville Dam and 

Astoria (Brown et al., 2009). Data from 

four acoustically tagged California sea 

lions in 2010 also indicate that the 

animals move though the area below 

Bonneville Dam down to the receivers 

located below the CRC project site 

rapidly both in the upriver or downriver 

directions (Wright, 2010). Although the 

data apply to California sea lions, Steller 

sea lions and harbor seals similarly have 

no incentive to stay near the CRC 

project area, in contrast with a strong 

incentive to quickly reach optimal 

foraging grounds at the Bonneville Dam, 

and are thus expected to also pass the 

project area quickly. Therefore, 

pinnipeds are not expected to be 

exposed to a significant duration of 

construction sound. 

It is possible that deterrence of 

passage through the project area could 

be a concern. However, given the 800- 

m width of the Columbia River and the 

rarity of impact pile driving on opposite 

sides of the river (approximately 1–2 

days total throughout the approximately 

4-year construction period), passage 

should not be hindered. Vibratory 

installation or removal of piles at more 

than one pier complex would likely 

occur at the same time on occasion 

during construction and demolition. 

During construction and demolition, 

space limitations due to barge size and 

limitations on the amount of equipment 

available are anticipated to be limiting 

factors for the contractor. Vibratory 

installation of steel casings, pipe piles, 

and sheet piles are calculated to exceed 

behavioral disturbance thresholds at 

large distances; thus, the entire width of 

the channel would be affected by sound 

above the disturbance threshold even if 

only one pier complex was being 

worked on. However, because these 

sound levels are lower than those 

produced by ADDs at Bonneville Dam— 

which have shown only limited efficacy 

in deterring pinnipeds—and because 

pinnipeds transiting the Region of 

Activity will be highly motivated to 

complete transit, deterrence of passage 

is not anticipated to occur. 

Debris Removal—The reactions of 

pinnipeds to sound from debris removal 

(a non-pulsed sound) have received 

virtually no study. Previous studies 

indicate that dredging sound has 

resulted in avoidance reactions in 

marine mammals; however, the number 

of studies is small and limited to only 

a handful of locations. Thomsen et al. 

(2009) caution that, given the limited 

number of studies, the existing 

published data may not be 

representative and that it is therefore 

impossible to extrapolate the potential 

effects from one area to the next. 

In a review of the available literature 

regarding the effects of dredging sound 

on marine mammals, Richardson et al. 

(1995) found studies only related to 

whales and porpoises, and none related 

to pinnipeds. The review did, however, 

find studies related to the response of 

pinnipeds to ‘‘other construction 

activities’’, which may be applicable to 

dredging sound. Three studies of ringed 

seals during construction of artificial 

islands in Alaska showed mostly mild 

reactions ranging from negligible to 

temporary local displacement. Green 

and Johnson (1983, as cited in 

Richardson et al. [1995]) observed that 

some ringed seals moved away from the 

disturbance source within a few 

kilometers of construction. Frost and 

Lowry (1988, as cited in Richardson et 

al. [1995]) and Frost et al. (1988, as cited 

in Richardson et al., 1995) noted that 

ringed seal density within 3.7 km of 

construction was less than seal density 

in areas located more than 3.7 km away. 

Harbor seals in Kachemak Bay, Alaska, 

continued to haul out despite 

construction of hydroelectric facilities 

located 1,600 m away. Finally, Gentry 

and Gilman (1990) reported that the 

strongest reaction to quarrying 

operations on St. George Island in the 

Bering Sea was an alert posture when 

heavy equipment occurred within 100 

m of northern fur seals. 

There are no established levels of 

underwater debris removal sound 

shown to cause injury to pinnipeds. 

However, since the maximum expected 

debris removal sound levels on the CRC 

project are below the established injury 

threshold, it is unlikely that this activity 

would produce sound levels that are 

injurious to pinnipeds. Additionally, 

the limited body of literature does not 

include any reports of injuries caused 

by sound from underwater excavation. 

Debris removal sound is likely to exceed 

the disturbance threshold for only a 

short distance from the source 

(approximately 631 m). Specific 

responses to sound above this level may 

range from no response to avoidance to 

minor disruption of migration and/or 

feeding. Alternatively, pinnipeds may 

become habituated to elevated sound 

levels (NMFS, 2005; Stansell, 2009). 

This is consistent with the literature, 


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which reports only the following 

behavioral responses to these types of 

sound sources: No reaction, alertness, 

avoidance, and habituation. NMFS 

(2005) posits that continuous sound 

levels of 120 dB rms may elicit 

responses such as avoidance, diving, or 

changing foraging locations. 

Debris removal is only estimated to 

occur for up to 7 days over the 4-year 

construction period in North Portland 

Harbor. If this activity overlaps with 

pinniped presence, behavioral 

disturbance is expected to be brief and 

temporary, and restricted to individuals 

that are transiting the North Portland 

Harbor portion of the Region of Activity. 

Because many of the individual 

pinnipeds transiting the Region of 

Activity are already habituated to 

hazing at Bonneville Dam and to high 

levels of existing noise throughout the 

lower Columbia River, it is expected 

that they would not be especially 

sensitive to a marginal increase in 

existing noise. Thus, due to the short 

duration of this sound, its location only 

in North Portland Harbor and the high 

level of existing disturbance throughout 

the lower Columbia River, sound 

generated from debris removal is not 

expected to result in disturbance that 

would rise to the level of Level B 

harassment. 

Vessel Operations—Various types of 

vessels, including barges, tug boats, and 

small craft, would be present in the 

Region of Activity at various times. 

Vessel traffic would continually traverse 

the in-water CRC project area, with 

activities centered on Piers 2 through 7 

of the Columbia River and the new 

North Portland Harbor bents. Such 

vessels already use the Region of 

Activity in moderately high numbers; 

therefore, the vessels to be used in the 

Region of Activity do not represent a 

new sound source, only a potential 

increase in the frequency and duration 

of these sound source types. 

There are very few controlled tests or 

repeatable observations related to the 

reactions of pinnipeds to vessel noise. 

However, Richardson et al. (1995) 

reviewed the literature on reactions of 

pinnipeds to vessels, concluding overall 

that pinnipeds showed high tolerance to 

vessel noise. One study showed that, in 

water, sea lions tolerated frequent 

approach of vessels at close range. 

Because the Region of Activity is 

heavily traveled by commercial and 

recreational craft, it seems likely that 

pinnipeds that transit the Region of 

Activity are already habituated to vessel 

noise, thus the additional vessels that 

would occur as a result of CRC project 

activities would likely not have an 

additional effect on these pinnipeds. 

Therefore, CRC project vessel noise in 

the Region of Activity is unlikely to rise 

to the level of Level B harassment. 

Physical Disturbance—Vessels, inwater structures, and over-water 

structures have the potential to cause 

physical disturbance to pinnipeds, 

although in-water and over-water 

structures would cover no more than 

20 percent of the entire channel width 

at one time (CRC, 2010). As previously 

mentioned, various types of vessels 

already use the Region of Activity in 

high numbers. Tug boats and barges are 

slow moving and follow a predictable 

course. Pinnipeds would be able to 

easily avoid these vessels while 

transiting through the Region of 

Activity, and are likely already 

habituated to the presence of numerous 

vessels, as the lower Columbia River 

and North Portland Harbor receive high 

levels of commercial and recreational 

vessel traffic. Therefore, vessel strikes 

are extremely unlikely and, thus, 

discountable. Potential encounters 

would likely be limited to brief, 

sporadic behavioral disturbance, if any 

at all. Such disturbances are not likely 

to result in a risk of Level B harassment 

of pinnipeds transiting the Region of 

Activity. 

Hearing Impairment and Other 

Physiological Effects 

Temporary or permanent hearing 

impairment is a possibility when marine 

mammals are exposed to very strong 

sounds. Non-auditory physiological 

effects might also occur in marine 

mammals exposed to strong underwater 

sound. Possible types of non-auditory 

physiological effects or injuries that may 

occur in mammals close to a strong 

sound source include stress, 

neurological effects, bubble formation, 

and other types of organ or tissue 

damage. It is possible that some marine 

mammal species (i.e., beaked whales) 

may be especially susceptible to injury 

and/or stranding when exposed to 

strong pulsed sounds, particularly at 

higher frequencies. Non-auditory 

physiological effects are not anticipated 

to occur as a result of CRC activities. 

The following subsections discuss the 

possibilities of TTS and PTS. 

TTS—TTS, reversible hearing loss 

caused by fatigue of hair cells and 

supporting structures in the inner ear, is 

the mildest form of hearing impairment 

that can occur during exposure to a 

strong sound (Kryter, 1985). While 

experiencing TTS, the hearing threshold 

rises and a sound must be stronger in 

order to be heard. TTS can last from 

minutes or hours to (in cases of strong 

TTS) days. For sound exposures at or 

somewhat above the TTS threshold, 

hearing sensitivity in both terrestrial 

and marine mammals recovers rapidly 

after exposure to the sound ends. 

NMFS considers TTS to be a form of 

Level B harassment rather than injury, 

as it consists of fatigue to auditory 

structures rather than damage to them. 

Pinnipeds have demonstrated complete 

recovery from TTS after multiple 

exposures to intense sound, as 

described in the studies below (Kastak 

et al., 1999, 2005). The NMFSestablished 190-dB criterion is not 

considered to be the level above which 

TTS might occur. Rather, it is the 

received level above which, in the view 

of a panel of bioacoustics specialists 

convened by NMFS before TTS 

measurements for marine mammals 

became available, one could not be 

certain that there would be no injurious 

effects, auditory or otherwise, to 

pinnipeds. Therefore, exposure to sound 

levels above 190 dB does not necessarily 

mean that an animal has incurred TTS, 

but rather that it may have occurred. 

Few data on sound levels and durations 

necessary to elicit mild TTS have been 

obtained for marine mammals, and none 

of the published data concern TTS 

elicited by exposure to multiple pulses 

of sound. 

Human non-impulsive sound 

exposure guidelines are based on 

exposures of equal energy (the same 

sound exposure level [SEL]; SEL is 

reported here in dB re: 1 mPa2-s/re: 20 

mPa2-s for in-water and in-air sound, 

respectively) producing equal amounts 

of hearing impairment regardless of how 

the sound energy is distributed in time 

(NIOSH, 1998). Until recently, previous 

marine mammal TTS studies have also 

generally supported this equal energy 

relationship (Southall et al., 2007). 

Three newer studies, two by Mooney et 

al. (2009a,b) on a single bottlenose 

dolphin (Tursiops truncatus) either 

exposed to playbacks of U.S. Navy midfrequency active sonar or octave-band 

sound (4–8 kHz) and one by Kastak et 

al. (2007) on a single California sea lion 

exposed to airborne octave-band sound 

(centered at 2.5 kHz), concluded that for 

all sound exposure situations, the equal 

energy relationship may not be the best 

indicator to predict TTS onset levels. 

Generally, with sound exposures of 

equal energy, those that were quieter 

(lower SPL) with longer duration were 

found to induce TTS onset more than 

those of louder (higher SPL) and shorter 

duration. Given the available data, the 

received level of a single seismic pulse 

(with no frequency weighting) might 

need to be approximately 186 dB SEL in 

order to produce brief, mild TTS. 

In free-ranging pinnipeds, TTS 

thresholds associated with exposure to 


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brief pulses (single or multiple) of 

underwater sound have not been 

measured. However, systematic TTS 

studies on captive pinnipeds have been 

conducted (e.g., Bowles et al., 1999; 

Kastak et al., 1999, 2005, 2007; 

Schusterman et al., 2000; Finneran et 

al., 2003; Southall et al., 2007). Specific 

studies are detailed here: 

• Finneran et al. (2003) studied 

responses of two individual California 

sea lions. The sea lions were exposed to 

single pulses of underwater sound, and 

experienced no detectable TTS at 

received sound level of 183 dB peak 

(163 dB SEL). 

There were three studies conducted 

on pinniped TTS responses to nonpulsed underwater sound. All of these 

studies were performed in the same lab 

and on the same test subjects, and, 

therefore, the results may not be 

applicable to all pinnipeds or in field 

settings. 

• Kastak and Schusterman (1996) 

studied the response of harbor seals to 

non-pulsed construction sound, 

reporting TTS of about 8 dB. The seal 

was exposed to broadband construction 

sound for 6 days, averaging 6 to 7 hours 

of intermittent exposure per day, with 

SPLs from just approximately 90 to 105 

dB. 

• Kastak et al. (1999) reported TTS of 

approximately 4–5 dB in three species 

of pinnipeds (harbor seal, California sea 

lion, and northern elephant seal) after 

underwater exposure for approximately 

20 minutes to sound with frequencies 

ranging from 100–2,000 Hz at received 

levels 60–75 dB above hearing 

threshold. This approach allowed 

similar effective exposure conditions to 

each of the subjects, but resulted in 

variable absolute exposure values 

depending on subject and test 

frequency. Recovery to near baseline 

levels was reported within 24 hours of 

sound exposure. 

• Kastak et al. (2005) followed up on 

their previous work, exposing the same 

test subjects to higher levels of sound 

for longer durations. The animals were 

exposed to octave-band sound for up to 

50 minutes of net exposure. The study 

reported that the harbor seal 

experienced TTS of 6 dB after a 25- 

minute exposure to 2.5 kHz of octaveband sound at 152 dB (183 dB SEL). The 

California sea lion demonstrated onset 

of TTS after exposure to 174 dB and 206 

dB SEL. 

Southall et al. (2007) reported one 

study on TTS in pinnipeds resulting 

from airborne pulsed sound, while two 

studies examined TTS in pinnipeds 

resulting from airborne non-pulsed 

sound: 

• Bowles et al. (unpubl. data) 

exposed pinnipeds to simulated sonic 

booms. Harbor seals demonstrated TTS 

at 143 dB peak and 129 dB SEL. 

California sea lions and northern 

elephant seals experienced TTS at 

higher exposure levels than the harbor 

seals. 

• Kastak et al. (2004) used the same 

test subjects as in Kastak et al. 2005, 

exposing the animals to non-pulsed 

sound (2.5 kHz octave-band sound) for 

25 minutes. The harbor seal 

demonstrated 6 dB of TTS after 

exposure to 99 dB (131 dB SEL). The 

California sea lion demonstrated onset 

of TTS at 122 dB and 154 dB SEL. 

• Kastak et al. (2007) studied the 

same California sea lion as in Kastak et 

al. 2004 above, exposing this individual 

to 192 exposures of 2.5 kHz octave-band 

sound at levels ranging from 94 to 133 

dB for 1.5 to 50 min of net exposure 

duration. The test subject experienced 

up to 30 dB of TTS. TTS onset occurred 

at 159 dB SEL. Recovery times ranged 

from several minutes to 3 days. 

The sound level necessary to cause 

TTS in pinnipeds depends on exposure 

duration; with longer exposure, the 

level necessary to elicit TTS is reduced 

(Schusterman et al., 2000; Kastak et al., 

2005, 2007). For very short exposures 

(e.g., to a single sound pulse), the level 

necessary to cause TTS is very high 

(Finneran et al., 2003). Impact pile 

driving associated with CRC would 

produce maximum underwater pulsed 

sound levels estimated at 210 dB peak 

and 176 dB SEL with 10 dB of 

attenuation from an attenuation device 

(214 dB peak and 186 dB SEL without 

an attenuation device). Summarizing 

existing data, Southall et al. (2007) 

assume that pulses of underwater sound 

result in the onset of TTS in pinnipeds 

when received levels reach 212 dB peak 

or 171 dB SEL. They did not offer 

criteria for non-pulsed sounds. These 

recommendations are presented in order 

to discuss the likelihood of TTS 

occurring during the CRC project. The 

literature does not allow conclusions to 

be drawn regarding levels of underwater 

non-pulsed sound (e.g., vibratory pile 

installation) likely to cause TTS. With a 

sound attenuation device, TTS is not 

likely to occur based on estimated 

source levels from the CRC project. 

Without a sound attenuation device, it 

is estimated that the extent of the area 

in which underwater sound levels could 

potentially cause TTS is somewhere in 

between the extent of where the injury 

threshold occurs and the extent of 

where the disturbance threshold occurs 

(described previously in this document). 

Impact pile driving would produce 

initial airborne sound levels of 

approximately 112 dB peak at 160 ft 

(49 m) from the source, as compared to 

the level suggested by Southall et al. 

(2007) of 143 dB peak for onset of TTS 

in pinnipeds from multiple pulses of 

airborne sound. It is not expected that 

airborne sound levels would induce 

TTS in individual pinnipeds. 

Although underwater sound levels 

produced by the CRC project may 

exceed levels produced in studies that 

have induced TTS in pinnipeds, there is 

a general lack of controlled, quantifiable 

field studies related to this 

phenomenon, and existing studies have 

had varied results (Southall et al., 2007). 

Therefore, it is difficult to extrapolate 

from these data to site-specific 

conditions for the CRC project. For 

example, because most of the studies 

have been conducted in laboratories, 

rather than in field settings, the data are 

not conclusive as to whether elevated 

levels of sound would cause pinnipeds 

to avoid the Region of Activity, thereby 

reducing the likelihood of TTS, or 

whether sound would attract pinnipeds, 

increasing the likelihood of TTS. In any 

case, there are no universally accepted 

standards for the amount of exposure 

time likely to induce TTS. Lambourne 

(in CRC, 2010) posits that, in most 

circumstances, free-roaming Steller sea 

lions are not likely to remain in areas 

subjected to high sound levels long 

enough to experience TTS unless there 

is a particularly strong attraction, such 

as an abundant food source. While it 

may be inferred that TTS could 

theoretically result from the CRC 

project, it is impossible to quantify the 

magnitude of exposure, the duration of 

the effect, or the number of individuals 

likely to be affected. Exposure is likely 

to be brief because pinnipeds use the 

Region of Activity for transiting, rather 

than breeding or hauling out. In 

summary, it is expected that elevated 

sound would have only a negligible 

probability of causing TTS in individual 

seals and sea lions. 

PTS—When PTS occurs, there is 

physical damage to the sound receptors 

in the ear. In some cases, there can be 

total or partial deafness, whereas in 

other cases, the animal has an impaired 

ability to hear sounds in specific 

frequency ranges. 

There is no specific evidence that 

exposure to underwater industrial 

sounds can cause PTS in any marine 

mammal (see Southall et al., 2007). 

However, given the possibility that 

marine mammals might incur TTS, 

there has been further speculation about 

the possibility that some individuals 

occurring very close to industrial 

activities might incur PTS. Richardson 

et al. (1995) hypothesized that PTS 


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caused by prolonged exposure to 

continuous anthropogenic sound is 

unlikely to occur in marine mammals, at 

least for sounds with source levels up to 

approximately 200 dB. Single or 

occasional occurrences of mild TTS are 

not indicative of permanent auditory 

damage in terrestrial mammals. Studies 

of relationships between TTS and PTS 

thresholds in marine mammals are 

limited; however, existing data appear 

to show similarity to those found for 

humans and other terrestrial mammals, 

for which there is a large body of data. 

PTS might occur at a received sound 

level at least several decibels above that 

inducing mild TTS. 

Southall et al. (2007) propose that 

sound levels inducing 40 dB of TTS 

may result in onset of PTS in marine 

mammals. The authors present this 

threshold with precaution, as there are 

no specific studies to support it. 

Because direct studies on marine 

mammals are lacking, the authors base 

these recommendations on studies 

performed on other mammals. 

Additionally, the authors assume that 

multiple pulses of underwater sound 

result in the onset of PTS in pinnipeds 

when levels reach 218 dB peak or 186 

dB SEL. In air, sound levels are assumed 

to cause PTS in pinnipeds at 149 dB 

peak or 144 dB SEL (Southall et al., 

2007). Sound levels this high are not 

expected to occur as a result of the 

proposed activities. 

The potential effects to marine 

mammals described in this section of 

the document do not take into 

consideration the proposed monitoring 

and mitigation measures described later 

in this document (see the PROPOSED 

MITIGATION and PROPOSED 

MONITORING AND REPORTING 

sections). It is highly unlikely that 

marine mammals would receive sounds 

strong enough (and over a sufficient 

duration) to cause PTS (or even TTS) 

during the proposed CRC activities. 

When taking the mitigation measures 

proposed for inclusion in the 

regulations into consideration, it is 

highly unlikely that any type of hearing 

impairment would occur as a result of 

CRC’s proposed activities. 

Anticipated Effects on Marine Mammal 

Habitat 

Construction activities would likely 

impact pinniped habitat in the 

Columbia River and North Portland 

Harbor by producing temporary 

disturbances, primarily through 

elevated levels of underwater sound, 

reduced water quality, and physical 

habitat alteration associated with the 

structural footprint of the CRC bridges. 

Other potential temporary changes are 

passage obstruction and changes in prey 

species distribution during 

construction. Permanent changes to 

habitat would be produced primarily 

through the presence of new bridge 

piers in the Columbia River and in 

North Portland Harbor and removal of 

the existing piers in the Columbia River. 

A limited amount of debris removal in 

the North Portland Harbor may occur. 

The underwater sounds would occur 

as short-term pulses (i.e., minutes to 

hours), separated by virtually 

instantaneous and complete recovery 

periods. These disturbances are likely to 

occur several times a day for up to a 

week, 2–14 weeks per year, for 6 years 

(5 years of activity would be authorized 

under this rule). Water quality 

impairment would also occur as shortterm pulses (i.e., minutes to hours) 

during construction, most likely due to 

erosion during precipitation events, and 

would continue due to stormwater 

runoff for the design life of CRC. 

Physical habitat alteration due to 

modification and replacement of 

existing in-water and over-water 

structures would also occur 

intermittently during construction, and 

would remain as the final, as-built 

project footprint for the design life of 

CRC. 

Elevated levels of sound may be 

considered to affect the in-water habitat 

of pinnipeds via impacts to prey species 

or through passage obstruction 

(discussed later). However, due to the 

timing of the in-water work and the 

limited amount of pile driving that may 

occur on a daily basis, these effects on 

pinniped habitat would be temporary 

and limited in duration. Very few 

harbor seals are likely to be present in 

any case, and any pinnipeds that do 

encounter increased sound levels would 

primarily be transiting the action area in 

route to or from foraging below 

Bonneville Dam where fish concentrate, 

and thus unlikely to forage in the action 

area in anything other than an 

opportunistic manner. The direct loss of 

habitat available during construction 

due to sound impacts is expected to be 

minimal. 

Impacts to Prey Species 

Fish are the primary dietary 

component of pinnipeds in the Region 

of Activity. The Columbia River and 

North Portland Harbor provides 

migration and foraging habitat for 

sturgeon and lamprey, migration and 

spawning habitat for eulachon, and 

migration habitat for juvenile and adult 

salmon and steelhead, as well as some 

limited rearing habitat for juvenile 

salmon and steelhead. 

Impact pile driving would produce a 

variety of underwater sound levels. 

Underwater sound caused by vibratory 

installation would be less than impact 

driving (Caltrans, 2009; WSDOT, 

2010b). Oscillating and rotating steel 

casements for drilled shafts are not 

likely to elevate underwater sound to a 

level that is likely to cause injury or that 

would cause adverse changes to fish 

behavior on a long-term basis. 

Literature relating to the impacts of 

sound on marine fish species can be 

divided into categories which describe 

the following: (1) Pathological effects; 

(2) physiological effects; and (3) 

behavioral effects. Pathological effects 

include lethal and sub-lethal physical 

damage to fish; physiological effects 

include primary and secondary stress 

responses; and behavioral effects 

include changes in exhibited behaviors 

of fish. Behavioral changes might be a 

direct reaction to a detected sound or a 

result of anthropogenic sound masking 

natural sounds that the fish normally 

detect and to which they respond. The 

three types of effects are often 

interrelated in complex ways. For 

example, some physiological and 

behavioral effects could potentially lead 

ultimately to the pathological effect of 

mortality. Hastings and Popper (2005) 

reviewed what is known about the 

effects of sound on fish and identified 

studies needed to address areas of 

uncertainty relative to measurement of 

sound and the responses of fish. Popper 

et al. (2003/2004) also published a 

paper that reviews the effects of 

anthropogenic sound on the behavior 

and physiology of fish. Please see those 

sources for more detail on the potential 

impacts of sound on fish. 

Underwater sound pressure waves 

can injure or kill fish (e.g., Reyff, 2003; 

Abbott and Bing-Sawyer, 2002; Caltrans, 

2001; Longmuir and Lively, 2001; Stotz 

and Colby, 2001). Fish with swim 

bladders, including salmon, steelhead, 

and sturgeon, are particularly sensitive 

to underwater impulsive sounds with a 

sharp sound pressure peak occurring in 

a short interval of time (Caltrans, 2001). 

As the pressure wave passes through a 

fish, the swim bladder is rapidly 

squeezed due to the high pressure, and 

then rapidly expanded as the 

underpressure component of the wave 

passes through the fish. The pneumatic 

pounding may rupture capillaries in the 

internal organs as indicated by observed 

blood in the abdominal cavity and 

maceration of the kidney tissues 

(Caltrans, 2001). Although eulachon 

lack a swim bladder, they are also 

susceptible to general pressure wave 

injuries including hemorrhage and 

rupture of internal organs, as described 


tkelley on DSK3SPTVN1PROD with PROPOSALS2
23576 Federal Register / Vol. 77, No. 76 / Thursday, April 19, 2012 / Proposed Rules 

above, and damage to the auditory 

system. Direct take can cause 

instantaneous death, latent death within 

minutes after exposure, or can occur 

several days later. Indirect take can 

occur because of reduced fitness of a 

fish, making it susceptible to predation, 

disease, starvation, or inability to 

complete its life cycle. Effects to prey 

species are summarized here and are 

outlined in more detail in NMFS’ 

biological opinion. 

There are no physical barriers to fish 

passage within the Region of Activity, 

nor are there fish passage barriers 

between the Region of Activity and the 

Pacific Ocean. The proposed project 

would not involve the creation of 

permanent physical barriers; thus, longterm changes in pinniped prey species 

distribution are not expected to occur. 

Nevertheless, impact pile-driving 

would likely create a temporary 

migration barrier to all life stages of fish 

using the Columbia River and North 

Portland Harbor, although this would be 

localized. Cofferdams and temporary inwater work structures also may create 

partial barriers to the migration of 

juvenile fish in shallow-water habitat. 

Impacts to fish species distribution 

would be temporary during in-water 

work and hydroacoustic impacts from 

impact pile driving would only occur 

for limited periods during the day and 

only during the in-water work window 

established for this activity in 

conjunction with ODFW, WDFW, and 

NMFS. The overall effect to the prey 

base for pinnipeds is anticipated to be 

insignificant. 

Prey may also be affected by turbidity, 

contaminated sediments, or other 

contaminants in the water column. The 

CRC project involves several activities 

that could potentially generate turbidity 

in the Columbia River and North 

Portland Harbor, including pile 

installation, pile removal, installation 

and removal of cofferdams, installation 

of steel casings for drilled shafts, and 

debris removal. Because these actions 

would take place in a sandy substrate 

and would be limited to a small area 

and a brief portion of the work period, 

the increase in turbidity is expected to 

be small. Turbidity is not expected to 

cause mortality to fish species in the 

Region of Activity, and effects would 

probably be limited to temporary 

avoidance of the discrete areas of 

elevated turbidity (anticipated to be no 

more than 300 ft [91 m] from the source) 

for approximately 4–6 hours at a time 

(CRC, 2010), or effects such as abrasion 

to gills and alteration in feeding and 

migration behavior for fish close to the 

activity. Therefore, turbidity would 

likely have only insignificant effects to 

fish and, thus, insignificant effects on 

pinnipeds. 

The CRC project would minimize, 

avoid, or contain much of the potential 

sources of contamination, minimizing 

the risk of exposure to prey species of 

pinnipeds. The CRC project team 

would, in advance of in-water work, 

perform an extensive search for 

evidence of contamination, pinpointing 

the location, extent, and concentration 

of the contaminants. Then, BMPs would 

be implemented to ensure that the CRC 

project: (1) Avoids areas of 

contaminated sediment or (2) enables 

responsible parties to initiate cleanup 

activities for contaminated sediments 

occurring from construction activities 

within the Region of Activity. These 

BMPs would be developed and 

implemented in coordination with 

regulatory agencies. Because the CRC 

project would identify the locations of 

contaminated sediments and use BMPs 

to ensure that they do not become 

mobilized, there is little risk that the 

prey base of pinnipeds would be 

significantly affected by or exposed to 

contaminated sediments. 

Though treatment of runoff would 

occur, the ability to remove pollutants 

to a level without effect upon fish or 

that does not synergistically combine 

with other sources is technologically 

limited and unfeasible. Exposure to 

these ubiquitous contaminants even in 

low concentrations is likely to affect the 

survival and productivity of salmonid 

juveniles in particular (e.g., Loge et al., 

2006; Hecht et al., 2007; Johnson et al., 

2007; Sandahl et al., 2007; Spromberg 

and Meador, 2006). Short-term exposure 

to contaminants such as pesticides and 

dissolved metals may disrupt olfactory 

function (Hecht, 2007) and interfere 

with associated behaviors such as 

foraging, anti-predator responses, 

reproduction, imprinting (odor 

memories), and homing (the upstream 

migration to natal streams). The toxicity 

of these pollutants varies with water 

quality speciation and concentration. 

Regarding dissolved heavy metals, 

Santore et al. (2001) indicate that the 

presence of natural organic matter and 

changes in pH and hardness affect the 

potential for toxicity (increase and 

decrease). Additionally, organics (living 

and dead) can adsorb and absorb other 

pollutants such as polycyclic aromatic 

hydrocarbons (PAHs). The variables of 

organic decay further complicate the 

path and cycle of pollutants. 

The release of contaminants is likely 

to occur. Wind and water erosion is 

likely to entrain and transport soil from 

disturbed areas, contributing fine 

sediments that are likely to contain 

pollutants, and the use of heavy 

equipment, including stationary 

equipment like generators and cranes, 

also creates a risk that accidental spills 

of fuel, lubricants, hydraulic fluid, 

coolants, and other contaminants may 

occur. Petroleum-based contaminants, 

such as fuel, oil, and some hydraulic 

fluids, contain PAHs, which are acutely 

toxic to salmonids and other aquatic 

organisms at high levels of exposure and 

cause sublethal adverse effects on 

aquatic organisms at lower 

concentrations (Heintz et al., 1999, 

2000; Incardona et al., 2004, 2005, 

2006). 

However, due to the relatively small 

amount of time that any heavy 

equipment would be in the water and 

the use of proposed conservation 

measures, including site restoration 

after construction is complete, any 

increase in contaminants is likely to be 

small, infrequent, and limited to the 

construction period. In-water and nearwater construction would employ 

numerous BMPs and would comply 

with all required regulatory permits to 

ensure that contaminants do not enter 

surface water bodies. In the unlikely 

event of accidental release, BMPs and a 

Pollution Control and Contamination 

Plan (PCCP) would be implemented to 

ensure that contaminants are prevented 

from spreading and are cleaned up 

quickly. Therefore, contaminants are not 

likely to significantly affect fish and, 

thus, effects on pinnipeds are also likely 

to be insignificant. 

Physical Loss of Prey Species Habitat 

The project would lead to temporary 

physical loss of approximately 20,700 

ft2 (2,508 m2) of shallow-water habitat. 

Project elements responsible for 

temporary physical loss include the 

footprint of the numerous temporary 

piles associated with in-water work 

platforms, work bridges, tower cranes, 

oscillator support piles, cofferdams, and 

barge moorings in the Columbia River 

and North Portland Harbor. 

The in-water portions of the new 

structures would result in the 

permanent physical loss of 

approximately 250 ft2 (23 m2) of 

shallow-water habitat at pier complex 7 

in the Columbia River. Demolition of 

the existing Columbia River structures 

would permanently restore about 6,000 

ft2 (557 m2) of shallow-water habitat, 

and removal of one large overwater 

structure would permanently restore 

about 600 ft2 (56 m2) of shallow-water 

habitat. Overall, there would be a net 

permanent gain of about 5,345 ft2 (497 

m2) of shallow-water habitat in the 

Columbia River (CRC, 2010). At North 

Portland Harbor, there would be a 

permanent net loss of about 2,435 ft2


tkelley on DSK3SPTVN1PROD with PROPOSALS2
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(218 m2) of shallow-water habitat at all 

of the new in-water bridge bents. Note 

that all North Portland Harbor impacts 

are in shallow water. 

Physical loss of shallow-water habitat 

is of particular concern for rearing of 

subyearling migrant salmonids. In 

theory, in-water structures that 

completely block the nearshore may 

force these juveniles to swim into 

deeper-water habitats to circumvent 

them. Deep-water areas represent lower 

quality habitat because predation rates 

are higher there. Studies show that 

predators such as walleye (Stizostedion 

vitreum), northern pike-minnow 

(Ptychocheilus oregonensis), and other 

predatory fish occur in deepwater 

habitat for at least part of the year (e.g., 

Johnson, 1969; Ager, 1976; Paragamian, 

1989; Wahl, 1995; Pribyl et al., 2004). In 

the case of the CRC project, in-water 

portions of the structures would not 

pose a complete blockage to nearshore 

movement anywhere in the Region of 

Activity. Although these structures 

would cover potential rearing and 

nearshore migration areas, the habitat is 

not rare and is not of particularly high 

quality. Juveniles would still be able to 

use the abundant shallow-water habitat 

available for miles in either direction. 

Neither the permanent nor the 

temporary structures would necessarily 

force juveniles into deeper water, and 

therefore pose no definite added risk of 

predation. 

To the limited extent that the 

proposed actions do increase risk of 

predation, pinnipeds may accrue minor 

benefits. Alterations to adult eulachon 

and salmon behavior may make them 

more vulnerable to predation. Changes 

in cover that congregate fish or cause 

them to slow or pause migration would 

likely attract pinnipeds, which may 

then forage opportunistically. While 

individual pinnipeds are likely to take 

advantage of such conditions, it is not 

expected to increase overall predation 

rates across the run. Aggregating 

features would be small in comparison 

to the channel, and ample similar 

opportunities exist throughout the lower 

Columbia River. 

Physical loss of shallow-water habitat 

would have only negligible effects on 

foraging, migration, and holding of 

salmonids that are of the yearling age 

class or older. These life functions are 

not dependent on shallow-water habitat 

for these age classes. Furthermore, the 

lost habitat is not of particularly high 

quality. There is abundant similar 

habitat immediately adjacent along the 

shorelines of the Columbia River and 

throughout North Portland Harbor. The 

lost habitat represents only a small 

fraction of the remaining habitat 

available for miles in either direction. 

There would still be many acres of 

habitat for yearling or older age-classes 

of salmonids foraging, migrating, and 

holding in the Region of Activity. 

Physical loss of shallow-water habitat 

would have only negligible effects on 

eulachon and green sturgeon for the 

same reason. Thus, the effects to these 

elements of pinniped habitat would be 

minimal. 

The CRC project would cause a 

temporary physical loss of 

approximately 16,635 ft2 (1,545 m2) of 

deep-water habitat, consisting chiefly of 

coarse sand with a small proportion of 

gravel. CRC project elements 

responsible for temporary physical loss 

include the cofferdams and numerous 

temporary piles associated with inwater work platforms and moorings. 

The in-water portions of the new 

structures would result in the 

permanent physical loss of 

approximately 6,300 ft2 (585 m2) of 

deep-water habitat at pier complexes 2 

through 7 in the Columbia River. 

Demolition of the existing Columbia 

River piers would permanently restore 

about 21,000 ft2 (1,951 m2) of deepwater habitat. Overall, there would be a 

net permanent gain of about 15,000 ft2

(1,394 m2) of deep-water habitat in the 

Columbia River. 

Although there would be a temporary 

net physical loss of deep-water habitat, 

this is not expected to have a significant 

impact on prey species. The lost habitat 

is not rare or of particularly high 

quality, and there is abundant similar 

habitat in immediately adjacent areas of 

the Columbia River and for many miles 

both upstream and downstream. The 

lost habitat would represent a very 

small fraction (less than one percent) of 

the remaining habitat available. 

Additionally, the in-water portions of 

the permanent and temporary in-water 

structures would occupy no more than 

about one percent of the width of the 

Columbia River. Therefore, the 

structures would not be likely to pose a 

physical barrier to fish migration. 

In addition, compensatory mitigation 

for direct permanent habitat loss to 

jurisdictional waters from permanent 

pier placement would occur in 

accordance with requirements set by 

USACE, Oregon Department of State 

Lands (DSL), Washington Department of 

Ecology, ODFW, and WDFW. To meet 

these requirements, CRC is proposing to 

restore habitat in the lower Lewis River 

and lower Hood River. At the Hood 

River site, one mile of a historic side 

channel would be reconnected to the 

lower Hood River and an existing 

21-acre (8.5-ha) wetland, resulting in 

habitat benefits to salmonids and 

eulachon. At the Lewis River site, 

restoration of 18.5 acres (7.5 ha) of side 

channels would occur between the 

lower Lewis River and the lower 

Columbia River, resulting in habitat 

benefits to salmonid and other native 

species. Therefore, permanent habitat 

loss is expected to have a negligible 

impact to habitat for pinniped prey 

species. 

Due to the small size of the impact 

relative to the remaining habitat 

available, and the permanent benefits 

from habitat restoration, both temporary 

and permanent physical habitat loss are 

likely to be insignificant to fish and, 

thus, to the habitat and foraging 

opportunities of pinnipeds. 

Passage Obstruction 

The new overwater bridge structures 

would permanently decrease the overall 

footprint of piers below the OHW in the 

Columbia River and permanently 

increase the overall footprint of the 

piers below the OHW in North Portland 

Harbor. The permanent changes would 

be to riverine habitat; no pinniped haulout sites or rookeries would be affected. 

The effects to habitat in the action area 

would not result in significant changes 

to pinniped passage. Therefore, 

permanent changes due to bridge piers 

would not significantly affect 

pinnipeds. 

There are a variety of temporary 

structures that could potentially 

obstruct passage of pinnipeds including 

barges, moorings, tower cranes, 

cofferdams, and work platforms. 

Although there would be many such 

structures in the Region of Activity, they 

would cover no more than twenty 

percent of the entire channel width at 

one time. There would still be ample 

room for pinnipeds to navigate around 

these structures while transiting the 

action area. Pinnipeds may need to 

slightly alter their course as they move 

through the construction area to avoid 

these structures, but there is no 

potential for physical structures to 

completely block upstream or 

downstream movement. Due to the 

small size of the structures relative to 

the remaining portion of the river 

available, delays to pinniped 

movements would be negligible. 

Therefore, the effect of in-water and 

overwater structures on the ability of 

pinnipeds to pass upstream and 

downstream would be insignificant. 

The impact of temporary and 

permanent habitat changes from bridge 

construction is expected to be minimal 

to pinnipeds. The effects to pinnipeds 

from temporary and permanent habitat 

changes are summarized below. 


tkelley on DSK3SPTVN1PROD with PROPOSALS2
23578 Federal Register / Vol. 77, No. 76 / Thursday, April 19, 2012 / Proposed Rules 

• Sound disturbance: Temporary 

modification of habitat during in-water 

construction from elevated levels of 

sound may affect pinniped foraging; 

however, very few seals are in the 

Region of Activity and most sea lions 

are swimming upriver to forage below 

Bonneville Dam. Sound disturbance 

would not be continuous, would only 

occur temporarily as animals pass 

through the area and would be in the 

form of Level B harassment only. 

• Passage obstruction: The permanent 

changes to the overall footprint of the 

bridges in the Columbia River and North 

Portland Harbor would not affect 

pinniped breeding habitat or haul-out 

sites and would not affect passage 

significantly. Temporary structures 

during construction would not cover 

more than twenty percent of the entire 

channel and are not likely to 

significantly affect the ability of 

pinnipeds to pass through the 

construction area or delay their 

movements. 

• Changes in prey distribution and 

quality: The CRC project is likely to 

impact a small percentage of all salmon 

and steelhead runs that swim through 

the Region of Activity as a result of inwater work including pile installation. 

This impact would be temporary and 

would only occur during construction of 

the bridges in the Columbia River and 

North Portland Harbor and during 

demolition of the existing Columbia 

River Bridges. BMPs and minimization 

measures would avoid or limit the 

extent of the impact to prey species 

from sound, changes to water quality, 

and temporary structures. Short-term 

impacts to the prey base from project 

work do not represent a large part of the 

pinniped prey base in comparison to 

prey available through the entirety of 

their foraging range, which includes the 

Columbia River from Bonneville Dam to 

the mouth and foraging grounds off the 

Pacific Coast. Overall, effects to the prey 

base would be temporary, limited to the 

in-water work period over the CRC 

project duration, and would not cause 

measurable changes in the distribution 

or quality of prey available to 

pinnipeds. 

• Physical changes to prey species 

habitat: The new bridge structures 

would permanently decrease the overall 

footprint of piers below the OHW in the 

Columbia River and permanently 

increase the overall footprint of the 

piers below the OHW in North Portland 

Harbor. Habitat mitigation for direct 

permanent habitat loss to fish from 

permanent pier placement would occur 

in the lower Lewis River and lower 

Hood River and would provide longterm benefits to fish species in the lower 

Columbia River, resulting in long-term 

benefits to the pinniped prey base. 

Therefore, permanent habitat loss is 

expected to have a negligible impact to 

habitat for pinniped prey species. 

Temporary physical loss of habitat from 

temporary structures would only occur 

during the period of in-water work in 

the Columbia River and North Portland 

Harbor. These temporary losses are not 

expected to significantly affect the prey 

base for pinnipeds. 

In conclusion, NMFS has 

preliminarily determined that CRC’s 

proposed activities are not expected to 

have any habitat-related effects that 

could cause significant or long-term 

consequences for individual marine 

mammals or on the food sources that 

they utilize. 

Proposed Mitigation 

In order to issue an incidental take 

authorization under section 101(a)(5)(A) 

of the MMPA, NMFS must, where 

applicable, set forth the permissible 

methods of taking pursuant to such 

activity, and other means of effecting 

the least practicable adverse impact on 

such species or stock and their 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). NMFS and CRC worked to 

devise a number of mitigation measures 

designed to minimize impacts to marine 

mammals to the level of least 

practicable adverse impact, described in 

the following. 

The results from hydroacoustic 

monitoring during the test pile project, 

as well as results from modeling the 

zones of influence (ZOIs) (both 

described previously in this document 

and in following sections), were used to 

develop mitigation measures for CRC 

pile driving and removal activities. ZOIs 

are often used to effectively represent 

the mitigation zone that would be 

established around each pile to prevent 

Level A harassment of marine 

mammals. In addition to the specific 

measures described later, CRC would 

employ the following general mitigation 

measures: 

• All work would be performed 

according to the requirements and 

conditions of the regulatory permits 

issued by federal, state, and local 

governments. Seasonal restrictions, e.g., 

work windows, would be applied to the 

project to avoid or minimize potential 

impacts to protected species (including 

marine mammals) based on agreement 

with, and the regulatory permits issued 

by, DSL, WDFW, and USACE in 

consultation with ODFW, the U.S. Fish 

and Wildlife Service (USFWS), and 

NMFS. 

• Briefings would be conducted 

between the CRC project construction 

supervisors and the crew, marine 

mammal observer(s), and acoustical 

monitoring team prior to the start of all 

pile-driving activity, and when new 

personnel join the work, to explain 

responsibilities, communication 

procedures, marine mammal monitoring 

protocol, and operational procedures. 

The CRC project would contact the 

Bonneville Dam marine mammal 

monitoring team to obtain information 

on the presence or absence of pinnipeds 

prior to initiating pile driving in any 

discrete pile driving time period 

described in the project description. 

• CRC would comply with all 

applicable equipment sound standards 

and ensure that all construction 

equipment has sound control devices no 

less effective than those provided on the 

original equipment (i.e., equipment may 

not have been modified in such a way 

that it is louder than it was initially). 

• Permanent foundations for each inwater pier would be installed by means 

of drilled shafts. This approach 

significantly reduces the amount of 

impact pile driving, the size of piles, 

and amount of in-water sound. 

• Installation of piles using impact 

driving may only occur between 

September 15 and April 15 of the 

following year. 

• On an average work day, six piles 

could be installed using vibratory 

installation to set the piles, with impact 

driving then used to drive the piles to 

refusal per project specifications to meet 

load-bearing capacity requirements. 

This method reduces the number of 

daily pile strikes by over ninety percent. 

• No more than two impact pile 

drivers may be operated simultaneously 

within the same water body channel. 

• In waters with depths more than 2 

ft (0.67 m), a bubble curtain or other 

sound attenuation measure would be 

used for impact driving of pilings, 

except when testing device 

performance. As described previously, 

testing of the sound attenuation device 

would occur approximately weekly. 

This would require up to 7.5 minutes of 

unattenuated driving per week. If a 

bubble curtain or similar measure is 

used, it would distribute small air 

bubbles around 100 percent of the piling 

perimeter for the full depth of the water 

column. Any other attenuation measure 

(e.g., temporary sound attenuation pile) 

must provide 100 percent coverage in 

the water column for the full depth of 

the pile. A performance test of the 

sound attenuation device in accordance 

with the approved hydroacoustic 


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monitoring plan would be conducted 

prior to any impact pile driving. If a 

bubble curtain or similar measure is 

utilized, the performance test would 

confirm the calculated pressures and 

flow rates at each manifold ring. 

• For in-water heavy machinery work 

other than pile driving (e.g., standard 

barges, tug boats, barge-mounted 

excavators, or clamshell equipment 

used to place or remove material), if a 

marine mammal comes within 50 m 

(164 ft), operations shall cease and/or 

vessels shall reduce speed to the 

minimum level required to maintain 

steerage and safe working conditions. 

Monitoring and Shutdown 

Shutdown Zones—For all pile driving 

and removal activities, a shutdown zone 

(defined as, at minimum, the area in 

which SPLs equal or exceed 190 dB 

rms) would be established. The purpose 

of a shutdown zone is to define an area 

within which shutdown of activity 

would occur upon sighting of a marine 

mammal (or in anticipation of an animal 

entering the defined area), thus 

preventing injury, serious injury, or 

death of marine mammals. Although 

hydroacoustic data from the test pile 

project indicate that radial distances to 

the 190-dB threshold would be less than 

50 m, shutdown zones would 

conservatively be set at a minimum 

50 m. This precautionary measure is 

intended to further reduce any 

possibility of injury to marine mammals 

by incorporating a buffer to the 190-dB 

threshold within the shutdown area. 

Please see the discussion of ‘‘Distance to 

Sound Thresholds’’ and ‘‘Test Pile 

Project’’ under Description of Sound 

Sources, previously in this document. 

Disturbance Zones—For all pile 

driving and removal activities, a 

disturbance zone would be established. 

Disturbance zones are typically defined 

as the area in which SPLs equal or 

exceed 160 or 120 dB rms (for impact 

and vibratory pile driving, respectively). 

However, when the size of a disturbance 

zone is sufficiently large as to make 

monitoring of the entire area 

impracticable (as in the case of the 

120-dB zone here), the disturbance zone 

may be defined as some area that may 

reasonably be monitored. Here, the 

disturbance zone is defined for 

monitoring purposes as an area of 

800 m radius. Disturbance zones 

provide utility for monitoring 

conducted for mitigation purposes (i.e., 

shutdown zone monitoring) by 

establishing monitoring protocols for 

areas adjacent to the shutdown zones. 

Monitoring of disturbance zones enables 

PSOs to be aware of and communicate 

the presence of marine mammals in the 

project area but outside the shutdown 

zone and thus prepare for potential 

shutdowns of activity. However, the 

primary purpose of disturbance zone 

monitoring is for documenting incidents 

of Level B harassment; disturbance zone 

monitoring is discussed in greater detail 

later (see Proposed Monitoring and 

Reporting). 

Monitoring Protocols—Initial 

monitoring zones are based on worst 

case values measured during the test 

pile project and with the attenuation 

device operating during impact driving, 

and are presented in Table 15. A 

minimum distance of 50 m is used for 

all shutdown zones, even if actual or 

initial calculated distances are less. A 

maximum distance of 800 m is used for 

all disturbance zones for vibratory pile 

driving, even if actual or calculated 

values are greater. Monitoring of the full 

disturbance zone for these activities is 

impracticable. The data collected during 

the test pile project consistently support 

the belief that the coefficient of 

transmission loss increases with 

increasing range from the source pile, 

out to at least 800 m. To provide the 

best estimate of transmission loss at a 

specific range, the data were 

interpolated to one meter increments 

using a quadratic interpolation routine. 

To establish a disturbance zone for 

impact pile driving, an iterative solution 

was computed based on the interpolated 

transmission loss data. 

TABLE 15—DISTANCE TO INITIAL SHUTDOWN AND DISTURBANCE MONITORING ZONES FOR IN-WATER SOUND IN THE

COLUMBIA RIVER AND NORTH PORTLAND HARBOR

Pile type Hammer type 

Distance to monitoring zones (m) 1

190 dB2 160 dB2 120 dB2

18–24 in steel pipe 3 ....................................... Impact ............................................................. 50 258 N/A 

36–48 in steel pipe 4 ....................................... Impact ............................................................. 50 582 N/A 

48-in steel pipe ............................................... Vibratory ......................................................... 50 N/A 800 

120-in steel casing .......................................... Vibratory ......................................................... 50 N/A 800 

Sheet pile ........................................................ Vibratory ......................................................... 50 N/A 800 

1 Monitoring zones based on worst case values measured during test pile project and with the attenuation device operating during impact driving. A minimum distance of 50 m is used for all shutdown zones, even if actual or initial calculated distances are less. A maximum distance of 

800 m is used for all disturbance zones for vibratory pile driving, even if actual or calculated values are greater. For modeled values, see Tables 

11 and 12. 2All values unweighted and relative to 1 μPa. 3For 24-in pile, test pile data show a worst case source level of 191 dB rms with a worst-case attenuation of 8 dB and transmission loss coefficient based on quadratic interpolation of test pile data of 16.3. 4For 48-in pile, test pile data show a worst case source level of 201 dB RMS with a worst-case attenuation of 11 dB, and transmission loss 

coefficient based on quadratic interpolation of test pile data of 17.0. 

Data from the test pile project suggest 

that the majority of the energy from 

vibratory driving occurs in frequencies 

below 1,000 Hz, with energy levels 

gradually falling off at higher 

frequencies (CRC, 2011). For vibratory 

installation during the test pile study, 

the energy was not distinguishable 

above background levels by 800 m 

(2,625 ft) for all but one pile. Therefore, 

although transmission loss data were 

not conclusive—only one pile produced 

a signal that could be distinguished at 

all three monitoring stations, above 

background sound that was much 

higher than was previously measured 

for the action area—the modeled results 

for vibratory driving are validated by the 

empirical data, and it is likely that 

actual distances to the 120-dB threshold 

would be much less than modeled 

values. Piles were generally installed or 

extracted during the test pile study in 

less than 10 minutes. Vibratory 

extraction of piles would conservatively 

be treated similarly to vibratory 

installation, with similar monitoring 

zones. As described previously in this 

document (see section on ‘‘Test Pile 

Project’’), a maximum SPL of 181 dB for 

vibratory installation was recorded, 

while a maximum SPL of 176 dB was 

recorded for vibratory extraction. 


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The vibratory installation of steel 

casings and sheet piles was not 

measured as part of the test pile project. 

As noted in Table 11, modeled distance 

to the 120-dB isopleths resulting from 

vibratory installation of sheet pile was 

significantly less than that for vibratory 

installation of pipe pile. No published 

information is available on vibratory 

installation of 120-in (3 m) steel casings, 

which would be installed for drilled 

shafts. Published information from 

Caltrans (2007) shows that driving of 

36-in pile produced up to 175 dB rms 

while driving of 72-in pile produced up 

to 180 dB rms, both measured at 5 m 

from the pile. By extrapolating from 

these published values, CRC assumes 

the energy imparted through a larger 

casing would be up to 10 dB rms (an 

order of magnitude) higher than the 

highest value for a 72-in pile. In the 

absence of specific data, the initial 

disturbance zone for vibratory 

installation of steel casings and sheet 

pile would be established at 800 m, as 

described previously for vibratory pile 

driving. 

In order to accomplish appropriate 

monitoring for mitigation purposes, CRC 

would have an observer stationed on 

each active pile driving barge to closely 

monitor the shutdown zone as well as 

the surrounding area. In addition, CRC 

would post one shore-based observer, 

whose primary responsibility would be 

to record pinnipeds in the disturbance 

zone and to alert barge-based observers 

to the presence of pinnipeds in the 

disturbance zone, thus creating a 

redundant alert system for prevention of 

injurious interaction as well as 

increasing the probability of detecting 

pinnipeds in the disturbance zone. CRC 

estimates that shore-based observers 

would be able to scan approximately 

800 m (upstream and downstream) from 

the available observation posts; 

therefore, shore-based observers would 

be capable of monitoring the agreedupon disturbance zone. Visibility would 

be somewhat reduced by the existing 

bridges in the upstream direction. 

As described, at least two observers 

would be on duty during all pile 

driving/removal activity. The first 

observer would be positioned on a work 

platform or barge where the entire 50 m 

shutdown zone is clearly visible, with 

the second shore-based observer 

positioned to observe the disturbance 

zone from either the north or south bank 

of the river, depending on where the 

work platform or barge is positioned. 

Protocols would be implemented to 

ensure that coordinated communication 

of sightings occurs between observers in 

a timely manner. 

When pile driving/removal is 

occurring simultaneously at multiple 

sites, each site would have one observer 

dedicated to monitoring the shutdown 

zone for that site. Depending on the 

location of activity sites and the spacing 

of equipment, additional shore-based 

observers may be required to provide 

complete observational coverage of each 

site’s disturbance zone. That is, each 

site would have at least one observer, 

while one or multiple shore-based 

observers may be required. 

In summary: 

• CRC would implement a minimum 

shutdown zone of 50 m radius around 

all pile driving and removal activity, 

including installation of steel casings. 

The 50-m shutdown zone provides a 

buffer for the 190-dB threshold but is 

also intended to further avoid the risk 

of direct interaction between marine 

mammals and the equipment. 

• CRC would have a redundant 

monitoring system, in which one 

observer would be stationed on each 

pile driving barge, while one or multiple 

observers would be shore-based, as 

required to provide complete 

observational coverage of the reduced 

disturbance zone for each pile driving/ 

removal site. The former would be 

capable of providing comprehensive 

monitoring of the proposed shutdown 

zones, and would likely be able to 

effectively monitor a distance, in both 

directions, of approximately 800 m (the 

distance for the vibratory pile driving 

disturbance zone). These observers’ first 

priority would be shutdown zone 

monitoring in prevention of injurious 

interaction, with a secondary priority of 

counting takes by Level B harassment in 

the disturbance zone. The additional 

shore-based observer(s) would be able to 

monitor the same distances, but their 

primary responsibility would be 

counting of takes in the disturbance 

zone and communication with bargebased observers to alert them to 

pinniped presence in the action area. 

• The shutdown and disturbance 

zones would be monitored throughout 

the time required to drive a pile. If a 

marine mammal is observed within the 

disturbance zone, a take would be 

recorded and behaviors documented. 

However, that pile segment would be 

completed without cessation, unless the 

animal approaches or enters the 

shutdown zone, at which point all pile 

driving activities would be halted. 

• All shutdown and disturbance 

zones would either be based on 

empirical, site-specific data, or would 

initially be based on data for similar 

sources. For all activities, in-situ 

hydroacoustic monitoring would be 

conducted to either verify or determine 

the actual distances to these threshold 

zones, and the size of the zones would 

be adjusted accordingly based on 

received SPLs. As noted previously, the 

minimum shutdown zone would always 

be 50 m. 

The following measures would apply 

to visual monitoring: 

• If a small boat is used for 

monitoring, the boat would remain 50 

yd (46 m) from swimming pinnipeds in 

accordance with NMFS marine mammal 

viewing guidelines (NMFS, 2004). 

• If vibratory installation of steel pipe 

piles or casings occurs after dark, 

monitoring would be conducted with a 

night vision scope and/or other suitable 

device. Impact driving would only 

occur during daylight hours. 

• If the shutdown zone is obscured by 

fog or poor lighting conditions, pile 

driving would not be initiated until the 

entire shutdown zone is visible. Work 

that has been initiated appropriately in 

conditions of good visibility may 

continue during poor visibility. 

• The shutdown zone would be 

monitored for the presence of pinnipeds 

before, during, and after any pile driving 

activity. The shutdown zone would be 

monitored for 30 minutes prior to 

initiating the start of pile driving. If 

pinnipeds are present within the 

shutdown zone prior to pile driving, the 

start of pile driving would be delayed 

until the animals leave the shutdown 

zone of their own volition, or until 15 

minutes elapse without resighting the 

animal(s). 

• Monitoring would be conducted 

using binoculars. When possible, digital 

video or still cameras would also be 

used to document the behavior and 

response of pinnipeds to construction 

activities or other disturbances. 

• Each observer would have a radio 

or cell phone for contact with other 

monitors or work crews. Observers 

would implement shut-down or delay 

procedures when applicable by calling 

for the shut-down to the hammer 

operator. 

• A GPS unit or electric range finder 

would be used for determining the 

observation location and distance to 

pinnipeds, boats, and construction 

equipment. 

Monitoring would be conducted by 

qualified observers. In order to be 

considered qualified, observers must 

meet the following criteria: 

• Visual acuity in both eyes 

(correction is permissible) sufficient for 

discernment of moving targets at the 

water’s surface with ability to estimate 

target size and distance; use of 

binoculars may be necessary to correctly 

identify the target. 


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• Advanced education in biological 

science, wildlife management, 

mammalogy, or related fields (bachelor’s 

degree or higher is required). 

• Experience and ability to conduct 

field observations and collect data 

according to assigned protocols (this 

may include academic experience). 

• Experience or training in the field 

identification of pinnipeds, including 

the identification of behaviors. 

• Sufficient training, orientation, or 

experience with the construction 

operation to provide for personal safety 

during observations. 

• Writing skills sufficient to prepare a 

report of observations including but not 

limited to the number and species of 

pinnipeds observed; dates and times 

when in-water construction activities 

were conducted; dates and times when 

in-water construction activities were 

suspended to avoid potential incidental 

injury from construction sound of 

pinnipeds observed within a defined 

shutdown zone; and pinniped behavior. 

• Ability to communicate orally, by 

radio or in person, with project 

personnel to provide real-time 

information on pinnipeds observed in 

the area as necessary. 

Hydroacoustic Monitoring— 

Hydroacoustic monitoring would be 

conducted to determine actual values 

and distances to relevant acoustic 

thresholds, including for vibratory 

installation of steel casings and sheet 

piles. The initial disturbance zones 

would then be adjusted as appropriate 

on the basis of that information. If new 

zones are established based on SPL 

measurements, NMFS requires each 

new zone be based on the most 

conservative measurement (i.e., the 

largest zone configuration). Vibratory 

installation of steel pipe and sheet pile 

is not anticipated to produce 

underwater sound above the 190-dB 

injury threshold, while vibratory 

installation of steel casings is estimated 

to produce SPLs of 190 dB at a 

maximum distance of 5 m from the 

source. However, a minimum 50 m 

shutdown zone would be established for 

these activities as for impact driving. 

Table 15 shows initial distances for 

shutdown and disturbance zones for 

these activities. 

Ramp-Up and Shutdown 

The objective of a ramp-up is to alert 

any animals close to the activity and 

allow them time to move away, which 

would expose fewer animals to loud 

sounds, including both underwater and 

above water sound. This procedure also 

ensures that any pinnipeds missed 

during shutdown zone monitoring 

would move away from the activity and 

not be injured. Although impact driving 

would occur from September 15 through 

April 15, and vibratory driving would 

occur year-round, ramp-up would be 

required only from January 1 through 

June 15 of any year, during the period 

of greatest potential overlap with 

pinniped presence in the project area. 

The following ramp-up procedures 

would be used for in-water pile 

installation: 

• A ramp-up technique would be 

used at the beginning of each day’s inwater pile driving activities or if pile 

driving has ceased for more than 1 hour. 

• If a vibratory driver is used, 

contractors would be required to initiate 

sound from vibratory hammers for 15 

seconds at reduced energy followed by 

a 1-minute waiting period. The 

procedure would be repeated two 

additional times before full energy may 

be achieved. 

• If a non-diesel impact hammer is 

used, contractors would be required to 

provide an initial set of strikes from the 

impact hammer at reduced energy, 

followed by a 1-minute waiting period, 

then two subsequent sets. The reduced 

energy of an individual hammer cannot 

be quantified because they vary by 

individual drivers. Also, the number of 

strikes would vary at reduced energy 

because raising the hammer at less than 

full power and then releasing it results 

in the hammer ‘‘bouncing’’ as it strikes 

the pile, resulting in multiple ‘‘strikes’’. 

• If a diesel impact hammer is used, 

contractors would be required to turn on 

the sound attenuation device (e.g., 

bubble curtain or other approved sound 

attenuation device) for 15 seconds prior 

to initiating pile driving to flush 

pinnipeds from the area. 

The shutdown zone would also be 

monitored throughout the time required 

to drive a pile (or install a steel casing). 

If a pinniped is observed approaching or 

entering the shutdown zone, piling 

operations would be discontinued until 

the animal has moved outside of the 

shutdown zone. Pile driving would 

resume only after the animal is 

determined to have moved outside the 

shutdown zone by a qualified observer 

or after 15 minutes have elapsed since 

the last sighting of the animal within the 

shutdown zone. 

Work Zone Lighting 

If work occurs at night, temporary 

lighting would be used in the night 

work zones. During overwater 

construction, the contractor would use 

directional lighting with shielded 

luminaries to control glare and direct 

light onto work area, not surface waters. 

Additional Mitigation Measures 

In addition, NMFS and CRC, together 

with other relevant regulatory agencies, 

have developed a number of mitigation 

measures designed to protect fish 

through prevention or minimization of 

turbidity and disturbance and 

introduction of contaminants, among 

other things. These measures have been 

prescribed under the authority of 

statutes other than the MMPA, and are 

not a part of this proposed rulemaking. 

However, because these measures 

minimize impacts to pinniped prey 

species (either directly or indirectly, by 

minimizing impacts to prey species’ 

habitat), they are summarized briefly 

here. Additional detail about these 

measures may be found in CRC’s 

application. 

Timing restrictions would be used to 

avoid in-water work when ESA-listed 

fish are most likely to be present. Fish 

entrapment would be minimized by 

containing and isolating in-water work 

to the extent possible, through the use 

of drilled shaft casings and cofferdams. 

The contractor would provide a 

qualified fishery biologist to conduct 

and supervise fish capture and release 

activity to minimize risk of injury to 

fish. All pumps must employ fish screen 

that meet certain specifications in order 

to avoid entrainment of fish. A qualified 

biologist would be present during all 

impact pile driving operations to 

observe and report any indications of 

dead, injured, or distressed fishes, 

including direct observations of these 

fishes or increases in bird foraging 

activity. 

CRC would work to ensure minimum 

degradation of water quality in the 

project area, and would require the 

contractor to prepare a Water Quality 

Sampling Plan for conducting water 

quality monitoring for all projects 

occurring in-water in accordance with 

specific conditions. The Plan shall 

identify a sampling methodology as well 

as method of implementation to be 

reviewed and approved by the engineer. 

In addition, the contractor would 

prepare a Spill Prevention, Control, and 

Countermeasures (SPCC) Plan prior to 

beginning construction. The SPCC Plan 

would identify the appropriate spill 

containment materials; as well as the 

method of implementation. All 

equipment to be used for construction 

activities would be cleaned and 

inspected prior to arriving at the project 

site, to ensure no potentially hazardous 

materials are exposed, no leaks are 

present, and the equipment is 

functioning properly. Equipment that 

would be used below OHW would be 

identified; daily inspection and cleanup 


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procedures would insure that identified 

equipment is free of all external 

petroleum-based products. Should a 

leak be detected on heavy equipment 

used for the project, the equipment must 

be immediately removed from the area 

and not used again until adequately 

repaired. 

The contractor would also be required 

to prepare and implement a Temporary 

Erosion and Sediment Control (TESC) 

Plan and a Source Control Plan for 

project activities requiring clearing, 

vegetation removal, grading, ditching, 

filling, embankment compaction, or 

excavation. The BMPs in the plans 

would be used to control sediments 

from all vegetation removal or grounddisturbing activities. 

Conclusions 

NMFS has carefully evaluated the 

applicant’s proposed mitigation 

measures and considered a range of 

other measures in the context of 

ensuring that NMFS prescribes the 

means of effecting the least practicable 

adverse 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: 

• The manner in which, and the 

degree to which, the successful 

implementation of the measure is 

expected to minimize adverse impacts 

to marine mammals; 

• The proven or likely efficacy of the 

specific measure to minimize adverse 

impacts as planned; and 

• The practicability of the measure 

for applicant implementation. 

Based on our evaluation, NMFS has 

preliminarily determined that the 

mitigation measures proposed from both 

NMFS and CRC provide the means of 

effecting the least practicable adverse 

impact on marine mammal species or 

stocks and their habitat, paying 

particular attention to rookeries, mating 

grounds, and areas of similar 

significance. The proposed rule 

comment period will afford the public 

an opportunity to submit 

recommendations, views, and/or 

concerns regarding this action and the 

proposed mitigation measures. 

Proposed Monitoring and Reporting 

In order to issue an incidental take 

authorization (ITA) for an activity, 

section 101(a)(5)(A) 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 would result in 

increased knowledge of the species and 

of the level of taking or impacts on 

populations of marine mammals that are 

expected to be present in the proposed 

action area. 

CRC proposed a marine mammal 

monitoring plan in their application (see 

Appendix D of CRC’s application). The 

plan may be modified or supplemented 

based on comments or new information 

received from the public during the 

public comment period. All methods 

identified herein have been developed 

through coordination between NMFS 

and the design and environmental teams 

at CRC. The methods are based on the 

parties’ professional judgment 

supported by their collective knowledge 

of pinniped behavior, site conditions, 

and proposed project activities. Because 

pinniped monitoring has not previously 

been conducted at this site, aspects of 

these methods may warrant 

modification. Any modifications to this 

protocol would be coordinated with 

NMFS. A summary of the plan, as well 

as the proposed reporting requirements, 

is contained here. 

The intent of the monitoring plan is 

to: 

• Comply with the requirements of 

the MMPA as well as the ESA section 

7 consultation; 

• Avoid injury to pinnipeds through 

visual monitoring of identified 

shutdown zones and shut-down of 

activities when animals enter or 

approach those zones; and 

• To the extent possible, record the 

number, species, and behavior of 

pinnipeds in disturbance zones for pile 

driving and removal activities. 

As described previously, monitoring 

for pinnipeds would be conducted in 

specific zones established to avoid or 

minimize effects of elevated levels of 

sound created by the specified 

activities. Shutdown zones would not 

be less than 50 m, while initial 

disturbance zones would be based on 

site-specific data. Zones may be 

modified on the basis of actual recorded 

SPLs from acoustic monitoring. 

Visual Monitoring 

The established shutdown and 

disturbance zones would be monitored 

by qualified marine mammal observers 

for mitigation purposes, as well as to 

document marine mammal behavior and 

incidents of Level B harassment, as 

described here. CRC’s marine mammal 

monitoring plan (see Appendix D of 

CRC’s application) would be 

implemented, requiring collection of 

sighting data for each pinniped 

observed during the proposed activities 

for which monitoring is required, 

including impact or vibratory 

installation of steel pipe or sheet pile or 

steel casings. A qualified biologist(s) 

would be present on site at all times 

during impact pile driving or vibratory 

installation or removal of steel pile or 

casings. Disturbance zones, briefly 

described previously under Proposed 

Mitigation, are discussed in greater 

depth here. 

Disturbance Zone Monitoring— 

Disturbance zones, described previously 

in Proposed Mitigation, are defined in 

Table 15 for underwater sound. 

Monitoring zones for Level B 

harassment from airborne sound would 

be 650 m for harbor seals and 196 m for 

sea lions (corresponding to the 

anticipated extent of airborne sound 

reaching 90 and 100 dB, respectively). 

The size of the disturbance zone for 

vibratory pile installation or extraction 

would be approximately 800 m in both 

the upstream and downstream 

directions, corresponding with the area 

that can reasonably be monitored by a 

shore-based observer. Any sighted 

animals outside of this area would be 

recorded as takes, but it is impossible to 

guarantee that all animals would be 

observed or to make observations of 

fine-scale behavioral reactions to sound 

throughout this zone. Nevertheless, 

because any animals transiting the 

action area (and the larger disturbance 

zone) would pass through the monitored 

area, all animals may potentially be 

observed, and use of the smaller 

disturbance zone for monitoring 

purposes does not necessarily mean that 

a significant number of harassed 

animals would not be observed. 

Monitoring of disturbance zones would 

be implemented as described 

previously. 

The monitoring biologists would 

document all pinnipeds observed in the 

monitoring area. Data collection would 

include a count of all pinnipeds 

observed by species, sex, age class, their 

location within the zone, and their 

reaction (if any) to construction 

activities, including direction of 

movement, and type of construction that 

is occurring, time that pile driving 

begins and ends, any acoustic or visual 

disturbance, and time of the 

observation. Environmental conditions 

such as wind speed, wind direction, 

visibility, and temperature would also 

be recorded. No monitoring would be 

conducted during inclement weather 

that creates potentially hazardous 

conditions, as determined by the 

biologist, nor would monitoring be 

conducted when visibility is 

significantly limited, such as during 


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heavy rain or fog. During these times of 

inclement weather, in-water work that 

may produce sound levels in excess of 

190 dB rms would be halted; these 

activities would not commence until 

monitoring has started for the day. 

All monitoring personnel must have 

appropriate qualifications as identified 

previously, with qualifications to be 

certified by CRC (see Proposed 

Mitigation). These qualifications 

include education and experience 

identifying pinnipeds in the Columbia 

River and the ability to understand and 

document pinniped behavior. All 

monitoring personnel would meet at 

least once for a training session 

sponsored by CRC. Topics would 

include: Implementation of the protocol, 

identifying marine mammals, and 

reporting requirements. 

All monitoring personnel would be 

provided a copy of the LOA and final 

biological opinion for the project. 

Monitoring personnel must read and 

understand the contents of the LOA and 

biological opinion as they relate to 

coordination, communication, and 

identifying and reporting incidental 

harassment of pinnipeds. 

Hydroacoustic Monitoring 

Hydroacoustic monitoring would be 

conducted on a representative number 

of piles or casings, according to 

protocols developed and approved by 

NMFS and USFWS. The number, size, 

and location of piles or casings 

monitored would represent the variety 

of substrates and depths, as necessary, 

in both the Columbia River and North 

Portland Harbor. Hydroacoustic 

monitoring would be conducted as 

necessary to measure representative 

source levels for impact and vibratory 

installation and removal of piles and 

casings. Measurements would represent 

a worst-case for size, depth, and 

substrate for all materials and 

installation methods. For standard 

underwater sound monitoring, one 

hydrophone positioned at 10 m from the 

pile is used. Some additional initial 

monitoring at several distances from the 

pile is anticipated to determine sitespecific transmission loss and 

directionality of sound. This data would 

be used to establish the radii of the 

shutdown and disturbance zones for 

pinnipeds. 

One hydrophone would be placed at 

between 1 and 3 m above the bottom at 

a distance of 10 m from each pile being 

monitored. Hydrophones placed upriver 

and downriver (at the 200-, 400- and 

800-meter distances) would be placed at 

a depth greater than 5 m below the 

water surface or placed 1–3 meters 

above the bottom. A weighted tape 

measure would be used to determine the 

depth of the water. Each hydrophone 

would be attached to a nylon cord or a 

steel chain if the current is swift enough 

to cause strumming of the line. The 

nylon cord or chain would be attached 

to an anchor that would keep the line 

the appropriate distance from each pile. 

The nylon cord or chain would be 

attached to a buoy or raft at the surface 

and checked regularly to maintain the 

tightness of the line. The distances 

would be measured by a tape measure, 

where possible, or a range-finder for 

those hydrophones that are distant from 

the pile. There would be a direct line of 

sight between the pile and the 

hydrophone in all cases. GPS 

coordinates would be recorded for each 

hydrophone location. 

When the river velocity is greater than 

1 m/s, a flow shield around each 

hydrophone would be used to provide 

a barrier between the irregular, 

turbulent flow and the hydrophone. 

River velocity would be measured 

concurrent to sound measurements. If 

velocity is greater than 1 m/s, a 

correlation between sound levels and 

current speed would be made to 

determine whether the data is valid and 

should be included in the analysis. 

Hydrophone calibrations would be 

checked at the beginning of each day of 

monitoring activity. Prior to the 

initiation of pile driving, the 

hydrophones would be placed at the 

appropriate distances and depth as 

described. 

Prior to and during the pile driving 

activity environmental data would be 

gathered such as wind speed and 

direction, air temperature, humidity, 

surface water temperature, water depth, 

wave height, weather conditions, and 

other factors that could contribute to 

influencing the underwater sound levels 

(e.g., aircraft, boats). Start and stop time 

of each pile driving event and the time 

at which the bubble curtain or 

functional equivalent is turned on and 

off would be recorded. The chief 

construction inspector would supply 

the acoustics specialist with a 

description of the substrate 

composition, hammer model and size, 

hammer energy settings and any 

changes to those settings during the 

piles being monitored, depth pile 

driven, blows per foot for the piles 

monitored, and total number of strikes 

to drive each pile that is monitored. 

Proposed Reporting 

Reports of data collected during 

monitoring would be submitted to 

NMFS weekly. The reporting would 

include: 

• All data described previously under 

monitoring, including observation dates, 

times, and conditions; and 

• Correlations of observed behavior 

with activity type and received levels of 

sound, to the extent possible. 

CRC would also submit a report(s) 

concerning the results of all acoustic 

monitoring. Acoustic monitoring reports 

would include: 

• Size and type of piles. 

• A detailed description of any sound 

attenuation device used, including 

design specifications. 

• The impact hammer energy rating 

used to drive the piles, make and model 

of the hammer(s), and description of the 

vibratory hammer. 

• A description of the sound 

monitoring equipment. 

• The distance between hydrophones 

and depth of water at the hydrophone 

locations. 

• The depth of the hydrophones. 

• The distance from the pile to the 

water’s edge. 

• The depth of water in which the 

pile was driven. 

• The depth into the substrate that 

the pile was driven. 

• The physical characteristics of the 

bottom substrate into which the piles 

were driven. 

• The total number of strikes to drive 

each pile. 

• The background sound pressure 

level reported as the fifty percent CDF, 

if recorded. 

• The results of the hydroacoustic 

monitoring, including the frequency 

spectrum, ranges and means including 

the standard deviation/error for the peak 

and rms SPL’s, and an estimation of the 

distance at which rms values reach the 

relevant marine mammal thresholds and 

background sound levels. Vibratory 

driving results would include the 

maximum and overall average rms 

calculated from 30-s rms values during 

the drive of the pile. 

• A description of any observable 

pinniped behavior in the immediate 

area and, if possible, correlation to 

underwater sound levels occurring at 

that time. 

An annual report on marine mammal 

monitoring and mitigation would be 

submitted to NMFS, Office of Protected 

Resources, and NMFS, Northwest 

Regional Office. The annual reports 

would summarize information 

presented in the weekly reports and 

include data collected for each distinct 

marine mammal species observed in the 

project area, including descriptions of 

marine mammal behavior, overall 

numbers of individuals observed, 

frequency of observation, and any 

behavioral changes and the context of 


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the changes relative to activities would 

also be included in the annual reports. 

Additional information that would be 

recorded during activities and contained 

in the reports include: Date and time of 

marine mammal detections, weather 

conditions, species identification, 

approximate distance from the source, 

and activity at the construction site 

when a marine mammal is sighted. 

In addition to annual reports, NMFS 

proposes to require CRC to submit a 

draft comprehensive final report to 

NMFS, Office of Protected Resources, 

and NMFS, Northwest Regional Office, 

180 days prior to the expiration of the 

regulations. This comprehensive 

technical report would provide full 

documentation of methods, results, and 

interpretation of all monitoring during 

the first 4.5 years of the regulations. A 

revised final comprehensive technical 

report, including all monitoring results 

during the entire period of the 

regulations, would be due 90 days after 

the end of the period of effectiveness of 

the regulations. 

Adaptive Management 

The final regulations governing the 

take of marine mammals incidental to 

the specified activities at CRC would 

contain an adaptive management 

component. In accordance with 50 CFR 

216.105(c), regulations for the proposed 

activity must be based on the best 

available information. As new 

information is developed, through 

monitoring, reporting, or research, the 

regulations may be modified, in whole 

or in part, after notice and opportunity 

for public review. The use of adaptive 

management would allow NMFS to 

consider new information from different 

sources to determine if mitigation or 

monitoring measures should be 

modified (including additions or 

deletions) if new data suggest that such 

modifications are appropriate. 

The following are some of the 

possible sources of applicable data: 

• Results from CRC’s monitoring from 

the previous year; 

• Results from general marine 

mammal and sound research; or 

• Any information which reveals that 

marine mammals may have been taken 

in a manner, extent or number not 

authorized by these regulations or 

subsequent LOAs. 

If, during the effective dates of the 

regulations, new information is 

presented from monitoring, reporting, or 

research, these regulations may be 

modified, in whole or in part, after 

notice and opportunity of public review, 

as allowed for in 50 CFR 216.105(c). In 

addition, LOAs would be withdrawn or 

suspended if, after notice and 

opportunity for public comment, the 

Assistant Administrator finds, among 

other things, that the regulations are not 

being substantially complied with or 

that the taking allowed is having more 

than a negligible impact on the species 

or stock, as allowed for in 50 CFR 

216.106(e). That is, should substantial 

changes in marine mammal populations 

in the project area occur or monitoring 

and reporting show that CRC actions are 

having more than a negligible impact on 

marine mammals, then NMFS reserves 

the right to modify the regulations and/ 

or withdraw or suspend LOAs after 

public review. 

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 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].’’ Take by Level B 

harassment only is anticipated as a 

result of CRC’s proposed activities. Take 

of marine mammals is anticipated to be 

associated with the installation and 

removal of piles and installation of steel 

casings, via impact and vibratory 

methods, and debris removal. No take 

by injury, serious injury, or death is 

anticipated. 

Assumptions regarding numbers of 

pinnipeds and number of round trips 

per individual per year in the Region of 

Activity are based on information from 

ongoing pinniped research and 

management activities conducted in 

response to concern over California sea 

lion predation on fish populations 

concentrated below Bonneville Dam. An 

intensive monitoring program has been 

conducted in the Bonneville Dam 

tailrace since 2002, using surface 

observations to evaluate seasonal 

presence, abundance, and predation 

activities of pinnipeds. Minimum 

estimates of the number of pinnipeds 

present in the tailrace from 2002 

through 2011 are presented in Table 16. 

Bonneville Dam is the first dam on the 

river, located at RKm 235, and is upriver 

of the CRC project site, which is located 

at approximately RKm 170. The primary 

California sea lion haul-out in the 

Columbia River is located in the 

Columbia River estuary in Astoria, 

approximately 151 RKm downstream of 

the project. This haul-out is the site of 

trapping and tagging for research and 

monitoring of pinnipeds that reach the 

Bonneville Dam tailrace. 

TABLE 16—MINIMUM ESTIMATED TOTAL NUMBERS OF PINNIPEDS PRESENT AT BONNEVILLE DAM FROM 2002 THROUGH

2011 

Species 2002 2003 2004 2005 ** 2006 2007 2008 2009 2010 2011 

California sea lion ............................................ 30 104 99 81 72 71 82 54 89 54 

Steller sea lion * ............................................... 0 3 3 4 11 9 39 26 75 89 

Harbor seal ....................................................... 1 2 2 1 3 2 2 2 2 1 

Data from Stansell et al. 2010, pers. comm. Stansell, 2011. 

* Animals not uniquely identified through 2007. Numbers through 2007 represent the highest number seen on any one day for each year 

(Tackley et al., 2008a). 

** Regular observations did not begin until March 18 in 2005; minimum estimate should likely be considered somewhat higher than these numbers (Tackley et al., 2008a). 

Monitoring began as a result of the 

2000 FCRPS biological opinion, which 

required an evaluation of pinniped 

predation in the tailrace of Bonneville 

Dam. The objective of the study was to 

determine the timing and duration of 

pinniped predation activity, estimate 

the number of fish caught, record the 

number of pinnipeds present, identify 

and track individual California sea 

lions, and evaluate various pinniped 

deterrents used at the dam (Tackley et 

al., 2008a). The study period for 

monitoring was January 1 through May 

31, beginning in 2002. During the study 

period pinniped observations began 

after consistent sightings of at least one 

animal occurred. Tackley et al. (2008a) 


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notes that sightings began earlier each 

year from 2002 to 2004. Although some 

sightings were reported earlier in the 

season, full-time observations began 

March 21 in 2002, March 3 in 2003, and 

February 24, 2004 (Tackley et al., 

2008a). In 2005 observations began in 

April, but in 2006 through 2010 

observations began in January or early 

February (Tackley et al., 2008a, b; 

Stansell et al., 2009; Stansell and 

Gibbons, 2010). California sea lion and 

Steller sea lion arrival and departure 

dates at Bonneville Dam are compiled 

from the reports above and were 

detailed previously in Table 13 and 

Table 14. If arrival and departure dates 

were not available, the timing of surface 

observations within the January through 

May study period were recorded. 

Because regular observations in the 

study period generally began as sea 

lions were observed below Bonneville 

Dam, and sometimes reports stated that 

observations stopped as sea lion 

numbers dropped, the observation dates 

only give a general idea of first arrival 

and departure. Because acoustic 

telemetry data indicate that sea lions 

travel at fast rates between hydrophone 

locations above and below the CRC 

project area (see Brown et al., 2010), 

dates of first arrival at Bonneville Dam 

and departure from the dam are 

assumed to coincide closely with 

potential passage timing through the 

CRC project area. Table 17 details 

observation effort by year; data is not yet 

available for observations in 2011. 

TABLE 17—HOURS OF OBSERVATION FOR PINNIPEDS AT THE BONNEVILLE DAM TAILRACE, BY YEAR

2002 2003 2004 2005 2006 2007 2008 2009 2010 

662 1,356 553 1,108 3,647 4,433 5,131 3,455 3,609 

Pinniped species presence is 

determined by likelihood of occurrence 

near the CRC project construction 

activities based on general abundance at 

Bonneville Dam and the number of 

times individuals are estimated to make 

the trip to and from the dam in a year. 

Individuals observed at the dam are 

known to have passed the project site at 

least once; however, not all individuals 

that pass the project site would go all 

the way to the dam, although it is 

expected that the vast majority would. 

Therefore, the use of abundances at 

Bonneville Dam in estimating take 

would produce a slight 

underestimation. These estimates also 

assume that all pinnipeds that pass the 

project site would be exposed to project 

activities (e.g., pile installation would 

be occurring every time an individual 

passes the project site). However, 

project activities that may impact 

pinnipeds would not occur 24 hours a 

day; therefore, this assumption results 

in an overestimate of exposures. Table 

18 summarizes the estimated take. 

Harbor Seal 

During most of the year, it is possible 

that small numbers of adults and 

subadults of both sexes may be expected 

to transit through the Region of Activity. 

In general, harbor seals remain close to 

haul-out sites when foraging and 

resting. As described previously, there 

are no known harbor seal haul-out sites 

within or near the Region of Activity, 

with the nearest known haul-out sites at 

least 45 mi (72 km) downstream. 

Pupping sites are generally restricted to 

coastal estuaries and other areas along 

the Olympic Peninsula and Puget 

Sound. 

One to three harbor seals were 

documented below the dam in all 9 

years of surface observations. Estimates 

are minimums and are based on 

observations made only within the 

January through May timeframe, 

although harbor seals have been 

observed in very low numbers yearround near Bonneville Dam (Tackley et 

al., 2008a). However, based on salmon 

and steelhead run timing, as well as 

lamprey and smelt timing, seals would 

most likely occur during the same 

January through May period when sea 

lions are present. Based on the 

preceding information, CRC estimates a 

minimum of one to three adult or 

subadult harbor seals would be 

potentially exposed to in-water project 

activities each year. Based on the 

limited data available, CRC assumes that 

the number of individuals that actually 

pass by the CRC project area would be 

slightly higher than the highest 

minimum observed at the dam. CRC 

therefore conservatively estimates six 

individuals per year may potentially 

pass the project site. This may 

overestimate the number in some years. 

However, based on the consistency in 

the data, the number of individuals that 

have the potential to be exposed to 

project activities is likely to remain 

small in future years. 

The number of round trips made per 

individual year is difficult to discern 

from the limited data available. Because 

harbor seals are not uniquely identified 

in the observations at Bonneville Dam, 

repeat observations of the same 

individual may have been reported on 

different observation days. Only one to 

three harbor seals have been observed at 

Bonneville Dam in any year (although 

this may represent greater than three 

individuals). One may safely assume 

that each individual completes at least 

one round-trip past the project site, 

although it may be more; because of the 

lack of data regarding seal movement to 

and from the dam, it is difficult to 

justify a number of round-trips per 

individual. We do know that harbor 

seals occur only infrequently at the dam 

and, therefore, only a limited number of 

round-trips could occur per individual. 

CRC conservatively estimates that each 

individual may make up to two roundtrips. 

Based on known pupping and haulout locations, and the low number of 

observations of harbor seals at 

Bonneville Dam over the years, it is 

likely that very few harbor seals transit 

through the Region of Activity, and that 

those that do are subadults or adults. 

CRC conservatively estimates that up to 

six subadult or adult harbor seals 

(double the maximum number observed 

at Bonneville Dam to date) may transit 

the Region of Activity up to four times 

per year (two round-trips). 

California Sea Lion 

California sea lions are observed in 

the winter and spring (January through 

May) with only a limited number of 

exceptions. No haul-out sites are located 

within the Region of Activity and no 

breeding or pupping occurs in the 

Region of Activity. All animals 

documented in the Columbia River have 

been adult or juvenile males (Jeffries et 

al., 2000). Table 16 presents numbers of 

California sea lions observed at 

Bonneville Dam. Numbers are presented 

as minimums, because not all sea lions 

are able to be uniquely identified in all 

observations and therefore may not be 

in the count. Tackley et al. (2008) noted 

that individuals were not uniquely 

identified prior to 2008; thus, the 

numbers of sea lions estimated from 

2002 through 2007 were likely 

underestimated. During those years, 

Tackley et al. (2008) estimate that an 

additional 15 to 35 California sea lions 

may have been present, but observers 

were not able to uniquely identify them 

and therefore they are not represented 


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in the counts. In addition, the high 

number of 104 individuals present 

below the dam in 2003 occurred prior 

to hazing (started in 2005) or permanent 

removal (2008–2010) activities. CRC 

believes the high number is not 

representative of current levels, due to 

extensive efforts to deter sea lions. 

Permanent removal of forty 

individuals occurred from 2008–2010 

(Stansell et al., 2010). In 2010, the 

number of individual sea lions observed 

was a minimum of 89 individuals. Of 

the 89 individuals, fourteen were 

removed (Stansell et al., 2010). 

Typically, the percentage of individuals 

making their first appearance at 

Bonneville Dam has been approximately 

thirty percent; however, in 2010 the 

percentage of new individuals was 

approximately 65 percent (51 were first 

time visitors below the dam) (Stansell et 

al., 2010). The removal program is 

currently suspended by court order, 

further complicating the estimation of 

sea lion abundance at the dam in future 

years. Trends are particularly hard to 

discern because numbers passing the 

project site would be a reflection of the 

number of returning sea lions, numbers 

of sea lions successfully removed in 

future years (should the program be 

resumed), and numbers of new sea 

lions, none of which may be estimated 

on the basis of data indicating clear 

trends. 

Based on 2010 data, new animals 

would likely largely replace those 

removed (e.g., in 2010, fourteen animals 

were removed and 51 were first time 

visitors below the dam) and still 

possibly result in an overall increase in 

California sea lion numbers. It is 

possible that a more effective method of 

deterrence will be developed in the 

future, or continued removal efforts will 

result in the number of California sea 

lions stabilizing or decreasing in future 

years. However, spring Chinook 

(Oncorhynchus tshawytscha) returns to 

the Columbia River in 2010 were the 

third largest on record since 1938 (CBB 

2010), based on a preliminary summary 

(ODFW and WDFW 2010). If the 

numbers remain high or increase, it is 

possible that the numbers of sea lions 

foraging near Bonneville Dam may 

increase. 

CRC estimates that the number of sea 

lions passing the project site would be 

approximately 89 individuals (the 

minimum high count since significant 

effort toward sea lion deterrence began) 

annually. There is a substantial amount 

of uncertainty in this estimate; 

therefore, NMFS presents the take 

estimate with the caveat that the 

estimate of California sea lions 

potentially present in each year of inwater project work may need to be 

adapted using the most recent data and 

trends available in future years (see 

Adaptive Management). 

CRC examined satellite-linked and 

acoustic tracking reports of California 

sea lions to help estimate the number of 

times individual sea lions may pass the 

CRC project site. Tracking has been 

conducted on an almost annual basis 

since 2004. Based on data from 100 to 

150 animals, annual California sea lion 

round trips to the dam range from one 

to five trips per individual (CRC, 2010). 

Movements of 26 satellite-tagged sea 

lions captured in the Columbia River 

during three non-breeding seasons 

(2003–04, 2004–05, and 2006–07) are 

described by Wright et al. (2010). 

Duration below the Bonneville Dam 

ranged from 2 to 43 days (Wright et al., 

2010). The authors noted that 

movements of sea lions captured in the 

Columbia River varied considerably 

within and across individuals, and that 

estimating the mean number of trips to 

Bonneville Dam in a given season is 

problematic given that many animals 

were tagged after they may have already 

made one or more such trips (Wright et 

al., 2010). In 2009, six California sea 

lions were tagged in early April with 

acoustic transmitters, and four of those 

tagged had relatively long datasets 

(approximately 1–1.5 months) (Brown et 

al., 2009). After tagging, three of the 

animals made one round trip from 

Astoria to Bonneville Dam, and one 

made two round trips prior to final 

departure from Bonneville Dam by the 

end of May (Brown et al., 2009). The 

animals may have made additional trips 

prior to tagging in early April. Data from 

five animals tagged in 2010 indicate that 

at least one to four round-trips were 

made to Bonneville Dam from Astoria 

(Brown et al. 2010). Four animals were 

tagged in March or April for 22 to 51 

days. Of these four individuals, two 

made at least four trips, one made two 

trips and one made one trip. The fifth 

animal was tagged in May at the end of 

the season and departed immediately 

after capture. Again, the preliminary 

data do not include trips taken prior to 

tagging. 

Based on past data, the estimated 

number of times an individual sea lion 

would pass the CRC project site ranges 

from at least two to ten times per year 

(one to five roundtrips per year). 

However, the actual number is quite 

variable from individual to individual. 

Therefore, based on the data available, 

CRC conservatively estimates a 

maximum of ten trips (five round-trips) 

past the project site annually. 

In summary, CRC conservatively 

estimates that up to 89 California sea 

lions may travel through the Region of 

Activity, annually, in future years. The 

nearest haul-out site is 45 mi (72 km) 

from the Region of Activity, California 

sea lion hazing efforts at Bonneville 

Dam are expected to continue, and there 

is no information indicating that a large 

increase in the numbers of California 

sea lions traveling up the Columbia 

River to Bonneville Dam is likely. Each 

California sea lion could be behaviorally 

harassed ten times per year (five roundtrips). 

Steller Sea Lion 

Exposure of Steller sea lions to 

elevated sound levels in the Region of 

Activity is likely to occur from 

November through May, when primarily 

adult and subadult male Steller sea 

lions typically forage at Bonneville 

Dam. Steller sea lions are known to 

migrate through the Region of Activity 

as they transit between the dam and the 

ocean during this time period, often 

making multiple round-trip journeys. 

Beginning in 2008, individual sea lions 

have also been present during 

September or October, but in low 

numbers (Stansell et al., 2009, 2010; 

Tackley et al., 2008b). Therefore, 

exposure during fall months is possible 

in very low numbers, but less likely. 

There are no Steller sea lion haul-outs 

or breeding sites in the Region of 

Activity. The nearest known haul-out is 

located approximately 26 mi (42 km) 

upstream of the CRC project area, and 

the nearest breeding site is located more 

than 200 mi (322 km) from the CRC 

project area (NMFS, 2008b). Therefore, 

elevated sound levels would have no 

effect on individuals at breeding or 

haul-out sites. 

Similar to California sea lions, 

projections of Steller sea lion numbers 

estimated to pass the CRC project site 

during construction in future years are 

impossible to make with a high degree 

of confidence. Unlike California sea 

lions, ESA-listed Steller sea lions have 

not been subject to removal programs. 

Regular observations from 2002 through 

2011 showed an increase in minimum 

numbers observed from 0 to 89 

individuals, even though hazing efforts 

at the fish ladder entrances started in 

2005 and vessel-based hazing began in 

2006 (Scordino, 2010; Tackley et al., 

2008a; Stansell et al., 2009). In 2010, the 

minimum number observed of 75 

individuals was approximately triple 

the 2009 minimum of 26 individuals 

(Stansell and Gibbons, 2010); however, 

the 2009 minimum was reduced by one 

third from the 2008 minimum of 39. 

The minimum number of animals 

projected in future years would be 

expected to be at least 89 individuals 


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and may continue to increase based on 

recent past trends. However, there is 

very little certainty in this estimate, 

especially when it is projected into the 

future. It is possible a more effective 

method of deterrence would be 

developed in the future and the number 

of Steller sea lions may stabilize or 

decrease in future years. However, if 

trends in the numbers of fish continue, 

it is also possible that the number of 

Steller sea lions present would continue 

to increase. 

Acoustic and satellite-linked tracking 

data for Steller sea lions in the 

Columbia River are only available for 

six individuals, and most were only 

tracked for one month beginning at the 

end of March or during April of 2010 

(CRC, 2010). Additional data are 

available from two individuals that were 

tagged with only satellite-linked 

transmitters (which do not provide inriver movement data). From the limited 

dataset, seven individuals made one 

round trip from marine areas, and one 

individual made two round trips 

(Wright, 2010a). The number of round 

trips made earlier in the season, prior to 

tagging, is not included in the estimate 

and could increase the number of trips 

per individual. Like California sea lions, 

considerable variation within and across 

individuals may exist. Acoustic and 

satellite-linked data collection efforts 

will continue in the future and will 

better inform the estimate of number of 

round-trips Steller sea lions are likely to 

make past the CRC project area. 

Summary 

Based on past data, the number of 

times an individual Steller sea lion 

would pass the CRC project site ranges 

from a minimum of two to four times 

per year (one to two round-trips). 

Therefore, CRC estimates that 

individuals may transit the Region of 

Activity six times per year (three roundtrips). As for California sea lions, the 

significant uncertainty associated with 

these estimates may require adaptation 

of the estimates using the most recent 

data and trends available (see Adaptive 

Management). Based on trends in Steller 

sea lions identified below Bonneville 

Dam in recent years, CRC conservatively 

estimates a tripling of the minimum of 

75 individuals seen in 2010, to 225 

individuals that may transit the project 

site six times (three round-trips) each 

per year. 

TABLE 18—ESTIMATED NUMBER OF INDIVIDUALS EXPOSED TO PROPOSED ACTIVITIES PER YEAR

Species Sex/age class 

affected 

Estimated 

number of 

individuals 

per year 

Estimated number of exposures 

per individual per year * 

Total estimated take 

per year 

Harbor seal ..................................... Adult males or females .................. 6 4 (2 round-trips) ............................. 24 

California sea lion ........................... Subadult or adult males ................. 89 10 (5 round-trips) ........................... 890 

Steller sea lion ................................ Subadult or adult males ................. 225 6 (3 round-trips) ............................. 1,350 

* It is assumed that individuals exposed to CRC’s proposed activities would be in transit to/from Bonneville Dam to forage. Trips to Bonneville 

Dam are assumed to be round-trips to/from the mouth of the Columbia River. 

Negligible Impact and Small Numbers 

Analyses and Preliminary 

Determination 

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.’’ In making a 

negligible impact determination, NMFS 

considers a variety of factors, including 

but not limited to: (1) The number of 

anticipated mortalities; (2) the number 

and nature of anticipated injuries; (3) 

the number, nature, intensity, and 

duration of Level B harassment; and (4) 

the context in which the takes occur. 

Incidental take, in the form of Level 

B harassment only, is likely to occur 

primarily as a result of pinniped 

exposure to elevated levels of sound 

caused by impact and vibratory 

installation and removal of pipe and 

sheet pile and steel casings. No take by 

injury, serious injury, or death is 

anticipated or would be authorized. By 

incorporating the proposed mitigation 

measures, including pinniped 

monitoring and shut-down procedures 

described previously, harassment to 

individual pinnipeds from the proposed 

activities is expected to be limited to 

temporary behavioral impacts. CRC 

assumes that all individuals traveling 

past the project area would be exposed 

each time they pass the area and that all 

exposures would cause disturbance. 

NMFS agrees that this represents a 

worst-case scenario and is therefore 

sufficiently precautionary. There are no 

pinniped haul-outs or rookeries located 

within or near the Region of Activity. 

The nearest haul-out for California sea 

lions and harbor seals is approximately 

45 mi (72 km) downriver from the 

Region of Activity, while the nearest 

known haul-out for Steller sea lions is 

approximately 26 mi (42 km) upstream 

from the Region of Activity. 

The shutdown zone monitoring 

proposed as mitigation, and the small 

size of the zones in which injury may 

occur, makes any potential injury of 

pinnipeds extremely unlikely, and 

therefore discountable. Because 

pinniped exposures would be limited to 

the period they are transiting the 

disturbance zone, with potential repeat 

exposures (on return to the mouth of the 

Columbia River) separated by days to 

weeks, the probability of experiencing 

TTS is also considered unlikely. 

These activities may cause 

individuals to temporarily disperse from 

the area or avoid transit through the 

area. However, existing traffic sound, 

commercial vessels, and recreational 

boaters already occur in the area. Thus, 

it is likely that pinnipeds are habituated 

to these disturbances while transiting 

the Region of Activity and would not be 

significantly hindered from transit. 

Behavioral changes are expected to 

potentially occur only when an animal 

is transiting a disturbance zone at the 

same time that the proposed activities 

are occurring. 

In addition, it is unlikely that 

pinnipeds exposed to elevated sound 

levels would temporarily avoid 

traveling through the affected area, as 

they are highly motivated to travel 

through the action area in pursuit of 

foraging opportunities upriver (NMFS, 

2008e). Sea lions have shown increasing 

habituation in recent years to various 

hazing techniques used to deter the 

animals from foraging in the Bonneville 

tailrace area, including acoustic 

deterrent devices, boat chasing, and 

above-water pyrotechnics (Stansell et 

al., 2009). Many of the individuals that 

travel to the tailrace area return in 

subsequent years (NMFS, 2008). 

Therefore, it is likely that pinnipeds 


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would continue to pass through the 

action area even when sound levels are 

above disturbance thresholds. 

Although pinnipeds are unlikely to be 

deterred from passing through the area, 

even temporarily, they may respond to 

the underwater sound by passing 

through the area more quickly, or they 

may experience stress as they pass 

through the area. Sea lions already move 

quickly through the lower river on their 

way to foraging grounds below 

Bonneville Dam (transit speeds of 4.6 

km/hr in the upstream direction and 8.8 

km/hr in the downstream direction 

[Brown et al., 2010]). Any increase in 

transit speed is therefore likely to be 

slight. Another possible effect is that the 

underwater sound would evoke a stress 

response in the exposed individuals, 

regardless of transit speed. However, the 

period of time during which an 

individual would be exposed to sound 

levels that might cause stress is short 

given their likely speed of travel 

through the affected areas. In addition, 

there would be few repeat exposures for 

individual animals. Thus, it is unlikely 

that the potential increased stress would 

have a significant effect on individuals 

or any effect on the population as a 

whole. 

Therefore, NMFS finds it unlikely that 

the amount of anticipated disturbance 

would significantly change pinnipeds’ 

use of the lower Columbia River or 

significantly change the amount of time 

they would otherwise spend in the 

foraging areas below Bonneville Dam. 

Pinniped usage of the Bonneville Dam 

foraging area, which results in transit of 

the action area, is a relatively recent 

learned behavior resulting from human 

modification (i.e., fish accumulation at 

the base of the dam). Even in the 

unanticipated event that either change 

was significant and animals were 

displaced from foraging areas in the 

lower Columbia River, there are 

alternative foraging areas available to 

the affected individuals. NMFS does not 

anticipate any effects on haul-out 

behavior because there are no proximate 

haul-outs within the areas affected by 

elevated sound levels. All other effects 

of the proposed action are at most 

expected to have a discountable or 

insignificant effect on pinnipeds, 

including an insignificant reduction in 

the quantity and quality of prey 

otherwise available. 

Any adverse effects to prey species 

would occur on a temporary basis 

during project construction. Given the 

large numbers of fish in the Columbia 

River, the short-term nature of effects to 

fish populations, and extensive BMPs 

and minimization measures designed by 

NMFS in cooperation with CRC to 

protect fish during construction, as well 

as conservation and habitat mitigation 

measures that would continue into the 

future, the project is not expected to 

have significant effects on the 

distribution or abundance of potential 

prey species in the long term. All 

project activities would be conducted 

using the BMPs and minimization 

measures, which are described in detail 

in NMFS’ biological opinion, pursuant 

to section 7 of the ESA, on the effects 

of the CRC project on ESA-listed 

species. Therefore, these temporary 

impacts are expected to have a 

negligible impact on habitat for 

pinniped prey species. 

A detailed description of potential 

impacts to individual pinnipeds was 

provided previously in this document. 

The following sections put into context 

what those effects mean to the 

respective populations or stocks of each 

of the pinniped species potentially 

affected. 

Harbor Seal 

The Oregon/Washington coastal stock 

of harbor seals consisted of about 25,000 

animals in 1999 (Carretta et al., 2007). 

As described previously, both the 

Washington and Oregon portions of this 

stock have reached carrying capacity 

and are no longer increasing, and the 

stock is believed to be within its OSP 

level (Jeffries et al., 2003; Brown et al., 

2005). The estimated take of 24 

individuals per year by Level B 

harassment is small relative to a stable 

population of approximately 25,000 

(0.1 percent), and is not expected to 

impact annual rates of recruitment or 

survival of the stock. 

California Sea Lion 

The U.S. stock of California sea lions 

was estimated to be 238,000 in the 2007 

Stock Assessment Report and may be at 

carrying capacity, although more data 

are needed to verify that determination 

(Carretta et al., 2007). Generally, 

California sea lions in the Pacific 

Northwest are subadult or adult males 

(NOAA, 2008). The estimated take of 

890 individuals per year is small 

relative to a population of 

approximately 238,000 (0.4 percent), 

and is not expected to impact annual 

rates of recruitment or survival of the 

stock. 

Steller Sea Lion 

The total population of the eastern 

DPS of Steller sea lions is estimated to 

be within a range from approximately 

58,334 to 72,223 animals with an overall 

annual rate of increase of 3.1 percent 

throughout most of the range (Oregon to 

southeastern Alaska) since the 1970s 

(Allen and Angliss, 2010). In 2006, the 

NMFS Steller sea lion recovery team 

proposed removal of the eastern stock 

from listing under the ESA based on its 

annual rate of increase. CRC’s take 

estimate is conservative, assuming a 

three-fold increase above the largest 

minimum count in 2010. An increase of 

this magnitude occurred from 2009 to 

2010, and so may be warranted; 

however, that 1-year increase is not 

necessarily a reliable indicator of future 

trends and so may result in an 

overestimate of future take. The total 

estimated take of 1,350 individuals per 

year is small compared to a population 

of approximately 65,000 (2.1 percent). 

For California and Steller sea lions, 

individuals that may be disturbed 

would be males, so the anticipated 

behavioral harassment is not expected 

to impact recruitment or survival of the 

stock. For all species, because the type 

of incidental harassment is not expected 

to actually remove individuals from the 

population or decrease significantly 

their ability to feed or breed, this 

amount of incidental harassment is 

anticipated to have a negligible impact 

on the stock. 

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 preliminarily finds that CRC’s 

proposed activities would result in the 

incidental take of small numbers of 

marine mammals, by Level B 

harassment only, and that the total 

taking from CRC’s proposed activities 

would 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. Therefore, NMFS has 

determined that the total taking of 

affected species or stocks would not 

have an unmitigable adverse impact on 

the availability of such species or stocks 

for taking for subsistence purposes. 

Endangered Species Act (ESA) 

On January 19, 2011, NMFS 

concluded consultation with FHWA and 

FTA under section 7 of the ESA on the 

proposed activities in the Columbia 

River and North Portland Harbor and 

issued a biological opinion. The finding 

of that consultation was that the 

proposed activities may adversely affect 

but are not likely to jeopardize the 

continued existence of the eastern DPS 

of Steller sea lions as well as a number 


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of ESA-listed fish. NMFS has 

preliminarily determined that issuance 

of these regulations and subsequent 

LOAs would not have any impacts 

beyond those analyzed in the 2011 

biological opinion. 

National Environmental Policy Act 

(NEPA) 

CRC released a Draft Environmental 

Impact Statement (EIS) for the proposed 

activities in May 2008. The draft EIS 

analyzed the potential environmental 

and community effects of five 

alternatives against the project’s goals, 

as identified in the Statement of 

Purpose and Need. The Final EIS, 

released in September 2011, described 

additional analysis of potential 

environmental and community effects of 

the project and incorporated the 

comments received on the Draft EIS and 

public input received at more than 950 

community briefings, workshops and 

public meetings. Following a 30-day 

review period, the CRC federal oversight 

agencies (FHWA and FTA) selected an 

alternative for the project and signed a 

record of decision (ROD) on December 

7, 2011. Further information about 

CRC’s NEPA process, as well as the EIS 

and ROD, is available at 

www.columbiarivercrossing.com. 

Because NMFS was not a cooperating 

agency in the development of CRC’s EIS, 

NMFS will conduct a separate NEPA 

analysis for issuance of authorizations 

pursuant to section 101(a)(5)(A) of the 

MMPA for the activities proposed by 

CRC. 

Information Solicited 

NMFS requests interested persons to 

submit comments, information, and 

suggestions concerning the request and 

the content of the proposed regulations 

to govern the taking described herein 

(see ADDRESSES). 

Classification 

The Office of Management and Budget 

(OMB) has determined that this 

proposed rule is not significant for 

purposes of Executive Order 12866. 

Pursuant to section 605(b) of the 

Regulatory Flexibility Act (RFA), the 

Chief Counsel for Regulation of the 

Department of Commerce has certified 

to the Chief Counsel for Advocacy of the 

Small Business Administration (SBA) 

that this proposed rule, if adopted, 

would not have a significant economic 

impact on a substantial number of small 

entities. The SBA defines small entity as 

a small business, small organization, or 

a small governmental jurisdiction. 

Applying this definition, there are no 

small entities that are impacted by this 

proposed rule. This proposed rule 

impacts only the activities of CRC, 

which has submitted a request for 

authorization to take marine mammals 

incidental to bridge construction within 

the Columbia River, over the course of 

5 years. CRC is a joint project of ODOT 

and WSDOT, in cooperation with 

FHWA and FTA. Project staff 

coordinates with state and local 

agencies in both Oregon and 

Washington, and also collaborates with 

federal agencies and tribal governments. 

CRC is not considered to be a small 

governmental jurisdiction under the 

RFA’s definition. Under the RFA, 

governmental jurisdictions are 

considered to be small if they are 

‘‘governments of cities, counties, towns, 

townships, villages, school districts, or 

special districts, with a population of 

less than 50,000, unless an agency 

establishes, after opportunity for public 

comment, one or more definitions of 

such term which are appropriate to the 

activities of the agency and which are 

based on such factors as location in 

rural or sparsely populated areas or 

limited revenues due to the population 

of such jurisdiction, and publishes such 

definition(s) in the Federal Register.’’ 

Because this proposed rule impacts only 

the activities of CRC, which is not 

considered to be a small entity within 

SBA’s definition, the Chief Counsel for 

Regulation certified that this proposed 

rule will not have a significant 

economic impact on a substantial 

number of small entities. As a result of 

this certification, a regulatory flexibility 

analysis is not required and none has 

been prepared. 

Notwithstanding any other provision 

of law, no person is required to respond 

to nor shall a person be subject to a 

penalty for failure to comply with a 

collection of information subject to the 

requirements of the Paperwork 

Reduction Act (PRA) unless that 

collection of information displays a 

currently valid OMB control number. 

This proposed rule contains collectionof-information requirements subject to 

the provisions of the PRA. These 

requirements have been approved by 

OMB under control number 0648–0151 

and include applications for regulations, 

subsequent LOAs, and reports. Send 

comments regarding any aspect of this 

data collection, including suggestions 

for reducing the burden, to NMFS and 

the OMB Desk Officer (see ADDRESSES). 

List of Subjects in 50 CFR Part 217 

Exports, Fish, Imports, Indians, 

Labeling, Marine mammals, Penalties, 

Reporting and recordkeeping 

requirements, Seafood, Transportation. 

Dated: April 10, 2012. 

Alan D. Risenhoover, 

Acting Deputy Assistant Administrator for 

Regulatory Programs, National Marine 

Fisheries Service. 

For reasons set forth in the preamble, 

50 CFR part 217 is proposed to be 

amended as follows: 

PART 217—REGULATIONS 

GOVERNING THE TAKE OF MARINE 

MAMMALS INCIDENTAL TO 

SPECIFIED ACTIVITIES 

1. The authority citation for part 217 

continues to read as follows: 

Authority: 16 U.S.C. 1361 et seq. 

2. Subpart V is added to part 217 to 

read as follows: 

Subpart V—Taking of Marine Mammals 

Incidental to Columbia River Crossing 

Project, Washington and Oregon 

Sec. 

217.210 Specified activity and specified 

geographical region. 

217.211 Effective dates. 

217.212 Permissible methods of taking. 

217.213 Prohibitions. 

217.214 Mitigation. 

217.215 Requirements for monitoring and 

reporting. 

217.216 Letters of Authorization. 

217.217 Renewals and Modifications of 

Letters of Authorization. 

Subpart V—Taking of Marine Mammals 

Incidental to Columbia River Crossing 

Project, Washington and Oregon 

§ 217.210 Specified activity and specified 

geographical region. 

(a) Regulations in this subpart apply 

only to Columbia River Crossing (CRC) 

and those persons it authorizes to 

conduct activities on its behalf for the 

taking of marine mammals that occurs 

in the area outlined in paragraph (b) of 

this section and that occurs incidental 

to bridge construction and demolition 

associated with the CRC project. 

(b) The taking of marine mammals by 

CRC may be authorized in a Letter of 

Authorization (LOA) only if it occurs in 

the Columbia River or North Portland 

Harbor, in the states of Washington and 

Oregon. 

§ 217.211 Effective dates. 

[Reserved] 

§ 217.212 Permissible methods of taking. 

(a) Under LOAs issued pursuant to 

§ 216.106 and § 217.216 of this chapter, 

the Holder of the LOA (hereinafter 

‘‘CRC’’) may incidentally, but not 

intentionally, take marine mammals 

within the area described in 

§ 217.210(b) of this chapter, provided 

the activity is in compliance with all 

terms, conditions, and requirements of 


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the regulations in this subpart and the 

appropriate LOA. 

(b) The incidental take of marine 

mammals under the activities identified 

in § 217.210(a) of this chapter is limited 

to the indicated number of Level B 

harassment takes of the following 

species: 

(1) Harbor seal (Phoca vitulina)—120 

(an average of 24 annually) 

(2) California sea lion (Zalophus 

californianus)—4,450 (an average of 890 

annually) 

(3) Steller sea lion (Eumetopias 

jubatus)—6,750 (an average of 1,350 

annually) 

§ 217.213 Prohibitions. 

Notwithstanding takings 

contemplated in § 217.212(b) of this 

chapter and authorized by a LOA issued 

under § 216.106 and § 217.216 of this 

chapter, no person in connection with 

the activities described in § 217.210 of 

this chapter may: 

(a) Take any marine mammal not 

specified in § 217.212(b) of this chapter; 

(b) Take any marine mammal 

specified in § 217.212(b) of this chapter 

other than by incidental, unintentional 

Level B Harassment; 

(c) Take a marine mammal specified 

in § 217.212(b) of this chapter if NMFS 

determines such taking results in more 

than a negligible impact on the species 

or stocks of such marine mammal; or 

(d) Violate, or fail to comply with, the 

terms, conditions, and requirements of 

this subpart or a LOA issued under 

§ 216.106 and § 217.216 of this chapter. 

§ 217.214 Mitigation. 

(a) When conducting the activities 

identified in § 217.210(a) of this chapter, 

the mitigation measures contained in 

the LOA issued under § 216.106 and 

§ 217.216 of this chapter must be 

implemented. These mitigation 

measures include: 

(1) General Conditions: 

(i) Briefings shall be conducted 

between the CRC project construction 

supervisors and the crew, marine 

mammal observer(s), and acoustical 

monitoring team prior to the start of all 

pile driving activity, and when new 

personnel join the work, to explain 

responsibilities, communication 

procedures, marine mammal monitoring 

protocol, and operational procedures. 

The CRC project shall contact the 

Bonneville Dam marine mammal 

monitoring team to obtain information 

on the presence or absence of pinnipeds 

prior to initiating pile driving in any 

discrete pile driving time period 

described in the project description. 

(ii) CRC shall comply with all 

applicable equipment sound standards 

and ensure that all construction 

equipment has sound control devices no 

less effective than those provided on the 

original equipment. 

(iii) For in-water heavy machinery 

work other than pile driving (e.g., 

standard barges, tug boats, bargemounted excavators, or clamshell 

equipment used to place or remove 

material), if a marine mammal comes 

within 50 m of such activity, operations 

shall cease and vessels shall reduce 

speed to the minimum level required to 

maintain steerage and safe working 

conditions. 

(2) Pile Installation: 

(i) Permanent foundations for each inwater pier shall be installed by means 

of drilled shafts. 

(ii) All piles shall be installed using 

vibratory driving to the extent possible. 

Installation of piles using impact 

driving may only occur between 

September 15 and April 15 of the 

following year, during daylight hours 

only. No more than two impact pile 

drivers may be operated simultaneously 

within the same water body channel. 

(iii) In waters with depths more than 

2 ft (0.67 m), a bubble curtain or other 

sound attenuation measure shall be 

used for impact driving of pilings. If a 

bubble curtain or similar measure is 

used, it shall distribute small air 

bubbles around 100 percent of the piling 

perimeter for the full depth of the water 

column. Any other attenuation measure 

(e.g., temporary sound attenuation pile) 

must provide 100 percent coverage in 

the water column for the full depth of 

the pile. A performance test of the 

sound attenuation device in accordance 

with the approved hydroacoustic 

monitoring plan shall be conducted 

prior to any impact pile driving. If a 

bubble curtain or similar measure is 

utilized, the performance test shall 

confirm the calculated pressures and 

flow rates at each manifold ring. 

(3) Shutdown and Monitoring: 

(i) Shutdown zone: For all impact pile 

driving and vibratory pile driving and 

removal, or installation of steel casings, 

shutdown zones shall be established. 

These zones shall include all areas 

where underwater sound pressure levels 

(SPLs) are anticipated to equal or exceed 

190 dB re: 1 mPa rms. Shutdown zones 

shall be established on the basis of 

existing worst-case site-specific data for 

24- or 48-in steel pile, as appropriate, 

collected by CRC with NMFS approval, 

and shall be adjusted as indicated by the 

results of acoustic monitoring 

conducted during the specified 

activities, but shall not be less than 

50 m radius. 

(ii) Disturbance zone: For all impact 

pile driving and vibratory pile driving 

or removal, disturbance zones shall be 

established. For impact pile driving, 

these zones shall include all areas 

where underwater SPLs are anticipated 

to equal or exceed 160 dB re: 1 mPa rms, 

and shall be established on the basis of 

existing worst-case site-specific data for 

24- or 48-in steel pile, as appropriate, 

collected by CRC with NMFS approval. 

The zones shall be adjusted as indicated 

by the results of acoustic monitoring 

conducted during the specified 

activities. The actual size of the zone for 

vibratory pile driving and removal that 

includes all areas where underwater 

SPLs equal or exceed 120 dB re: 1 mPa 

rms shall be empirically determined and 

reported by CRC, and on-site biologists 

shall be aware of the size of this zone. 

However, because of its large size, 

monitoring of the entire zone may not 

be required but shall be conducted as 

described in paragraph (v) of this 

section. 

(A) Initial disturbance zones for 

vibratory installation or removal of steel 

pipe pile and sheet pile and vibratory 

installation of steel casings shall be set 

at 800 m. In-situ acoustic monitoring 

shall be performed to determine the 

actual distances to these zones, and the 

size of the zones shall be adjusted 

accordingly based on worst-case sitespecific data for vibratory installation of 

steel sheet pile and steel casings, but the 

area to be visually monitored shall not 

be larger than 800 m. 

(B) [Reserved] 

(iii) Airborne sound: Disturbance 

zones for pile driving and removal 

activity and steel casing installation, to 

include all areas where airborne SPLs 

are anticipated to equal or exceed 90 dB 

re: 20 mPa rms or 100 dB re: 20 mPa rms 

(for harbor seals and sea lions, 

respectively), shall be established. 

These zones shall be adjusted 

accordingly based on worst-case sitespecific data collected during acoustic 

monitoring of the specified activities. 

(iv) The shutdown and disturbance 

zones shall be monitored throughout the 

time required to drive a pile. If a marine 

mammal is observed within or 

approaching the shutdown zone, 

activity shall be halted as soon as it is 

safe to do so, until the animal is 

observed exiting the shutdown zone or 

15 minutes has elapsed. If a marine 

mammal is observed within the 

disturbance zone, a take shall be 

recorded and behaviors documented. 

(v) Monitoring of shutdown and 

disturbance zones shall occur for all pile 

driving and removal and steel casing 

installation activities. The following 

measures shall apply: 

(A) Shutdown and disturbance zones 

shall be monitored from a work 


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platform, barge, or other vantage point. 

If a small boat is used for monitoring, 

the boat shall remain 50 yd (46 m) from 

swimming pinnipeds. CRC shall at all 

times employ, at minimum, one 

Protected Species Observer (PSO) to be 

located on each barge or work platform 

engaging in pile driving or removal or 

steel casing installation and, at 

minimum, one PSO to be based on shore 

or at another appropriate vantage point, 

as determined by CRC. If a single shorebased PSO is unable to provide full 

observational coverage of disturbance 

zones when multiple pile driving or 

removal or steel casing installation 

activities are occurring simultaneously, 

additional shore-based PSOs shall be 

stationed so that such coverage is 

attained. For vibratory pile driving and 

removal or steel casing installation, CRC 

shall maintain comprehensive 

observation of a maximum disturbance 

zone of 800 m radial distance. 

(B) If the shutdown zone is obscured 

by fog or poor lighting conditions, pile 

driving or removal or steel casing 

installation shall not be initiated until 

the entire shutdown zone is visible. Pile 

driving or removal or steel casing 

installation may continue under such 

conditions if properly initiated. 

(C) The shutdown zone shall be 

monitored for the presence of pinnipeds 

before, during, and after any pile driving 

activity. The shutdown zone shall be 

monitored for 30 minutes prior to 

initiating the start of pile driving and for 

30 minutes following the completion of 

pile driving. If pinnipeds are present 

within the shutdown zone prior to pile 

driving, the start of pile driving shall be 

delayed until the animals leave the 

shutdown zone of their own volition or 

until 15 minutes has elapsed without 

observing the animal. 

(4) Ramp-up 

(i) A ramp-up technique shall be used 

at the beginning of each day’s in-water 

pile driving activities and if pile driving 

resumes after it has ceased for more 

than 1 hour. 

(ii) If a vibratory driver is used, 

contractors shall be required to initiate 

sound from vibratory hammers for 15 

seconds at reduced energy followed by 

a 1-minute waiting period. The 

procedure shall be repeated two 

additional times before full energy may 

be achieved. 

(iii) If a non-diesel impact hammer is 

used, contractors shall be required to 

provide an initial set of strikes from the 

impact hammer at reduced energy, 

followed by a 1-minute waiting period, 

then two subsequent sets. 

(iv) If a diesel impact hammer is used, 

contractors shall be required to turn on 

the sound attenuation device for 15 

seconds prior to initiating pile driving. 

(5) Additional mitigation measures as 

contained in a LOA issued under 

§ 216.106 and § 217.216 of this chapter. 

(b) [Reserved] 

§ 217.215 Requirements for monitoring 

and reporting. 

(a) Visual Monitoring Program: (1) 

CRC shall employ PSOs during in-water 

construction and demolition activities. 

All PSOs must receive advance NMFS 

approval after a review of their 

qualifications and NMFS-approved 

training. The PSOs shall be responsible 

for visually locating marine mammals in 

the shutdown and disturbance zones 

and, to the extent possible, identifying 

the species. PSOs shall record, at 

minimum, the following information: 

(i) A count of all pinnipeds observed 

by species, sex, and age class. 

(ii) Their location within the 

shutdown or disturbance zone, and their 

reaction (if any) to construction 

activities, including direction of 

movement. 

(iii) Activity that is occurring at the 

time of observation, including time that 

pile driving begins and ends, any 

acoustic or visual disturbance, and time 

of the observation. 

(iv) Environmental conditions, 

including wind speed, wind direction, 

visibility, and temperature. 

(2) Monitoring shall be conducted 

using appropriate binoculars. When 

possible, digital video or still cameras 

shall also be used to document the 

behavior and response of pinnipeds to 

construction activities or other 

disturbances. 

(3) Each monitor shall have a radio or 

cell phone for contact with other 

monitors or work crews. Observers shall 

implement shut-down or delay 

procedures when applicable by calling 

for the shut-down to the hammer 

operator. 

(4) A GPS unit or electric range finder 

shall be used for determining the 

observation location and distance to 

pinnipeds, boats, and construction 

equipment. 

(5) No monitoring shall be conducted 

during inclement weather that creates 

potentially hazardous conditions, as 

determined by the biologist on-site. No 

monitoring shall be conducted when 

visibility in the shutdown zone is 

significantly limited, such as during 

heavy rain or fog. During these times of 

inclement weather, in-water work that 

may produce sound levels in excess of 

190 dB rms must be halted; these 

activities may not commence until 

appropriate monitoring of the shutdown 

zone can take place. 

(b) Reporting—CRC must implement 

the following reporting requirements: 

(1) Reports of data collected during 

monitoring shall be submitted to NMFS 

weekly. The reports shall include: 

(i) All data required to be collected 

during monitoring, as described under 

217.215(a) of this chapter, including 

observation dates, times, and 

conditions; and 

(ii) Correlations of observed behavior 

with activity type and received levels of 

sound, to the extent possible. 

(2) CRC shall also submit a report(s) 

concerning the results of all acoustic 

monitoring. Acoustic monitoring reports 

shall include: 

(i) Size and type of piles. 

(ii) A detailed description of any 

sound attenuation device used, 

including design specifications. 

(iii) The impact hammer energy rating 

used to drive the piles, make and model 

of the hammer(s), and description of the 

vibratory hammer. 

(iv) A description of the sound 

monitoring equipment. 

(v) The distance between 

hydrophones and depth of water at the 

hydrophone locations. 

(vi) The depth of the hydrophones. 

(vii) The distance from the pile to the 

water’s edge. 

(viii) The depth of water in which the 

pile was driven. 

(ix) The depth into the substrate that 

the pile was driven. 

(x) The physical characteristics of the 

bottom substrate into which the piles 

were driven. 

(xi) The total number of strikes to 

drive each pile. 

(xii) The background sound pressure 

level reported as the fifty percent 

cumulative distribution function, if 

recorded. 

(xiii) The results of the hydroacoustic 

monitoring, including the frequency 

spectrum, ranges and means including 

the standard deviation/error for the peak 

and rms SPLs, and an estimation of the 

distance at which rms values reach the 

relevant marine mammal thresholds and 

background sound levels. Vibratory 

driving results shall include the 

maximum and overall average rms 

calculated from 30-s rms values during 

the drive of the pile. 

(xiv) A description of any observable 

pinniped behavior in the immediate 

area and, if possible, correlation to 

underwater sound levels occurring at 

that time. 

(3) Reporting Injured or Dead Marine 

Mammals 

(i) In the unanticipated event that the 

specified activity clearly causes the take 

of a marine mammal in a manner 

prohibited by a LOA (if issued), such as 


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an injury (Level A harassment), serious 

injury, or mortality, CRC shall 

immediately cease the specified 

activities and report the incident to the 

Chief of the Permits and Conservation 

Division, Office of Protected Resources, 

NMFS, and the Northwest Regional 

Stranding Coordinator, NMFS. The 

report must include the following 

information: 

(A) Time and date of the incident; 

(B) Description of the incident; 

(C) Environmental conditions (e.g., 

wind speed and direction, Beaufort sea 

state, cloud cover, and visibility); 

(D) Description of all marine mammal 

observations in the 24 hours preceding 

the incident; 

(E) Species identification or 

description of the animal(s) involved; 

(F) Fate of the animal(s); and 

(G) Photographs or video footage of 

the animal(s). 

Activities shall not resume until 

NMFS is able to review the 

circumstances of the prohibited take. 

NMFS will work with CRC to determine 

what measures are necessary to 

minimize the likelihood of further 

prohibited take and ensure MMPA 

compliance. CRC may not resume their 

activities until notified by NMFS. 

(ii) In the event that CRC discovers an 

injured or dead marine mammal, and 

the lead PSO determines that the cause 

of the injury or death is unknown and 

the death is relatively recent (e.g., in 

less than a moderate state of 

decomposition), CRC shall immediately 

report the incident to the Chief of the 

Permits and Conservation Division, 

Office of Protected Resources, NMFS, 

and the Northwest Regional Stranding 

Coordinator, NMFS. 

The report must include the same 

information identified in 

217.215(b)(3)(i) of this chapter. 

Activities may continue while NMFS 

reviews the circumstances of the 

incident. NMFS will work with CRC to 

determine whether additional 

mitigation measures or modifications to 

the activities are appropriate. 

(iii) In the event that CRC discovers 

an injured or dead marine mammal, and 

the lead PSO determines that the injury 

or death is not associated with or related 

to the activities authorized in the LOA 

(e.g., previously wounded animal, 

carcass with moderate to advanced 

decomposition, or scavenger damage), 

CRC shall report the incident to the 

Chief of the Permits and Conservation 

Division, Office of Protected Resources, 

NMFS, and the Northwest Regional 

Stranding Coordinator, NMFS, within 

24 hours of the discovery. CRC shall 

provide photographs or video footage or 

other documentation of the stranded 

animal sighting to NMFS. 

(4) Annual Reports. 

(i) An annual report summarizing all 

pinniped monitoring and construction 

activities shall be submitted to NMFS, 

Office of Protected Resources, and 

NMFS, Northwest Regional Office 

(specific contact information to be 

provided in LOA) each year. 

(ii) The annual reports shall include 

data collected for each distinct marine 

mammal species observed in the project 

area. Description of marine mammal 

behavior, overall numbers of 

individuals observed, frequency of 

observation, and any behavioral changes 

and the context of the changes relative 

to activities shall also be included in the 

annual reports. Additional information 

that shall be recorded during activities 

and contained in the reports include: 

Date and time of marine mammal 

detections, weather conditions, species 

identification, approximate distance 

from the source, and activity at the 

construction site when a marine 

mammal is sighted. 

(5) Five Year Comprehensive Report. 

(i) CRC shall submit a draft 

comprehensive final report to NMFS, 

Office of Protected Resources, and 

NMFS, Northwest Regional Office 

(specific contact information to be 

provided in LOA) 180 days prior to the 

expiration of the regulations. This 

comprehensive technical report shall 

provide full documentation of methods, 

results, and interpretation of all 

monitoring during the first 4.5 years of 

the activities conducted under the 

regulations in this Subpart. 

(ii) CRC shall submit a revised final 

comprehensive technical report, 

including all monitoring results during 

the entire period of the LOAs, 90 days 

after the end of the period of 

effectiveness of the regulations to 

NMFS, Office of Protected Resources, 

and NMFS, Northwest Regional Office 

(specific contact information to be 

provided in LOA). 

§ 217.216 Letters of Authorization. 

(a) To incidentally take marine 

mammals pursuant to these regulations, 

CRC must apply for and obtain a LOA. 

(b) A LOA, unless suspended or 

revoked, may be effective for a period of 

time not to exceed the expiration date 

of these regulations. 

(c) If an LOA expires prior to the 

expiration date of these regulations, 

CRC must apply for and obtain a 

renewal of the LOA. 

(d) In the event of projected changes 

to the activity or to mitigation and 

monitoring measures required by an 

LOA, CRC must apply for and obtain a 

modification of the LOA as described in 

§ 217.217 of this chapter. 

(e) The LOA shall set forth: 

(1) Permissible methods of incidental 

taking; 

(2) Means of effecting the least 

practicable adverse impact (i.e., 

mitigation) on the species, its habitat, 

and on the availability of the species for 

subsistence uses; and 

(3) Requirements for monitoring and 

reporting. 

(f) Issuance of the LOA shall be based 

on a determination that the level of 

taking will be consistent with the 

findings made for the total taking 

allowable under these regulations. 

(g) Notice of issuance or denial of a 

LOA shall be published in the Federal 

Register within 30 days of a 

determination. 

§ 217.217 Renewals and Modifications of 

Letters of Authorization. 

(a) A LOA issued under § 216.106 and 

§ 217.216 of this chapter for the activity 

identified in § 217.210(a) of this chapter 

shall be renewed or modified upon 

request by the applicant, provided that: 

(1) The proposed specified activity and 

mitigation, monitoring, and reporting 

measures, as well as the anticipated 

impacts, are the same as those described 

and analyzed for these regulations 

(excluding changes made pursuant to 

the adaptive management provision in 

§ 217.217(c)(1) of this chapter), and (2) 

NMFS determines that the mitigation, 

monitoring, and reporting measures 

required by the previous LOA under 

these regulations were implemented. 

(b) For LOA modification or renewal 

requests by the applicant that include 

changes to the activity or the mitigation, 

monitoring, or reporting (excluding 

changes made pursuant to the adaptive 

management provision in 

§ 217.217(c)(1) of this chapter) that do 

not change the findings made for the 

regulations or result in no more than a 

minor change in the total estimated 

number of takes (or distribution by 

species or years), NMFS may publish a 

notice of proposed LOA in the Federal 

Register, including the associated 

analysis illustrating the change, and 

solicit public comment before issuing 

the LOA. 

(c) A LOA issued under § 216.106 and 

§ 217.216 of this chapter for the activity 

identified in § 217.210(a) of this chapter 

may be modified by NMFS under the 

following circumstances: 

(1) Adaptive Management—NMFS 

may modify (including augment) the 

existing mitigation, monitoring, or 

reporting measures (after consulting 

with CRC regarding the practicability of 

the modifications) if doing so creates a 


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reasonable likelihood of more 

effectively accomplishing the goals of 

the mitigation and monitoring set forth 

in the preamble for these regulations. 

(i) Possible sources of data that could 

contribute to the decision to modify the 

mitigation, monitoring, or reporting 

measures in an LOA: 

(A) Results from CRC’s monitoring 

from the previous year(s). 

(B) Results from other marine 

mammal and/or sound research or 

studies. 

(C) Any information that reveals 

marine mammals may have been taken 

in a manner, extent or number not 

authorized by these regulations or 

subsequent LOAs. 

(ii) If, through adaptive management, 

the modifications to the mitigation, 

monitoring, or reporting measures are 

substantial, NMFS will publish a notice 

of proposed LOA in the Federal 

Register and solicit public comment. 

(2) Emergencies—If NMFS determines 

that an emergency exists that poses a 

significant risk to the well-being of the 

species or stocks of marine mammals 

specified in § 217.212(b) of this chapter, 

an LOA may be modified without prior 

notice or opportunity for public 

comment. Notice would be published in 

the Federal Register within 30 days of 

the action. 

[FR Doc. 2012–9086 Filed 4–18–12; 8:45 am] 

BILLING CODE 3510–22–P 


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