Small Takes of Marine Mammals Incidental to Specified Activities; San Francisco-Oakland Bay Bridge, Pile Installation Demonstration Project, San Francisco Bay, CA

SUMMARY: NMFS has received a request from the Federal Highway Agency

(FHA) on behalf of the California Department of Transportation

(CALTRANS) for the harassment of marine mammals incidental to a pile

installation demonstration project (PIDP) at the San Francisco-Oakland

Bay Bridge (SF-OBB), San Francisco Bay (the Bay), CA. Under the Marine

Mammal Protection Act (MMPA), NMFS is requesting comments on its

proposal to authorize CALTRANS to incidentally take, by harassment,

small numbers of marine mammals in the above mentioned area for a

period of 1 year.

DATES: Comments and information must be received no later than February

7, 2000.

ADDRESSES: Comments on the application should be addressed to Donna

Wieting, Chief, Marine Mammal Conservation Division,

Office of Protected Resources, NMFS, 1315 East-West Highway, Silver

Spring, MD 20910-3225. A copy of the application and a list of

references used in this document may be obtained by writing to this

address or by telephoning one of the contacts listed here.

FOR FURTHER INFORMATION CONTACT: Kenneth R. Hollingshead, (301) 713-

2055 ext 128, or Tina Fahy, (562) 980-4023.

SUPPLEMENTARY INFORMATION:

Background

Section 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 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.

Permission may be granted if NMFS finds that the taking will have a

negligible impact on the species or stock(s) and will not have an

unmitigable adverse impact on the availability of the species or

stock(s) for subsistence uses and if the permissible methods of taking

and requirements pertaining to the 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.''

Subsection 101(a)(5)(D) of the MMPA established an expedited

process by which citizens of the United States can apply for an

authorization to incidentally take small numbers of marine mammals by

harassment. The MMPA now defines ``harassment'' as:

...any act of pursuit, torment, or annoyance which (a) has the

potential to injure a marine mammal or marine mammal stock in the

wild; or (b) 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.

Subsection 101(a)(5)(D) establishes a 45-day time limit for NMFS

review of an application followed by a 30-day public notice and comment

period on any proposed authorizations for the incidental harassment of

small numbers of marine mammals. Within 45 days of the close of the

comment period, NMFS must either issue or deny issuance of the

authorization.

[[Page 1084]]

Summary of Request

On November 22, 1999, NMFS received an application from the FHA on

behalf of CALTRANS, requesting authorization of an Incidental

Harassment Authorization (IHA) for the possible harassment of small

numbers of Pacific harbor seals (Phoca vitulina), and California sea

lions (Zalophus californianus) incidental to conducting the PIDP at the

SF-OBB.

CALTRANS is currently in the planning stages of the SF-OBB East

Span Seismic Safety Project (ESSSP). The ESSSP would include driving

large piles into the Bay bottom. One of the hammers anticipated to be

used for this task is larger than any pile-driving hammer previously

used in the Bay. Due to the untested nature of these hammers and piles

in the Bay, a pile installation demonstration is needed. The PIDP will

provide CALTRANS with an opportunity to measure resulting sound

pressure levels (SPL), both in air and under water, record impacts to

marine mammals and experiment with measures to reduce potential harm to

marine mammals prior to general use on SF-OBB piles.

The PIDP site is located between Yerba Buena Island (YBI) and

Oakland, in the area to the north of and between existing SF-OBB east

span piers E6 and E9 (see figures 1 and 2 of the application). The PIDP

site is approximately 2.0 km (1.24 mi) from northeast of the YBI harbor

seal haul-out site, which is located immediately to the west of the

lighthouse on the southernmost tip of the island.

The anticipated pier foundations for the ESSSP will consist of

large diameter (up to 110-m (361-ft) long), steel pipe piles that will

be driven into the Bay floor. Current plans anticipate using 2.5-m

(8.2-ft) diameter piles for a majority of the foundations and smaller

1.5-m (4.9-ft) diameter pipe piles for others.

Accurately predicting the characteristics of pile driving prior to

field-testing is not possible because piles of this size and length

have not previously been installed in Bay substrates and there is

limited experience with driving piles of this size. Therefore, given

the unprecedented nature of this work in the Bay, this PIDP will

provide CALTRANS with an opportunity to gather important data regarding

in-air and underwater sound pressure levels generated by the pile

driving activities. In addition, it will also provide an opportunity to

gather data from experimental measures to attenuate elevated SPLs,

thereby reducing the potential for harm to marine mammals. Information

obtained from this demonstration potentially may prove valuable for

forecasting anticipated impacts of pile installation activities

associated with a larger SF-OBB east span construction, which will

require the installation of approximately 350 piles of variable

diameter.

Project Description

The PIDP includes driving three full-scale steel pipe piles (2.438

m (8.0 ft) in diameter, 110 m (361 ft) long) at two locations (two at a

primary site and one at an alternate site) near the existing SF-OBB

east span alignment. Each pile consists of four segments of variable

length and wall thickness that will each be driven, subsequently welded

to another segment, and driven again until the full desired length and

depth of the pile is achieved. Due to the nature of this work, the

majority of the project time will be spent on surface support

activities, such as picking up the pile segments, placing the segment

in the correct spot and welding the segments together. Actual pile

driving will only occur for a small fraction of the project's duration.

Please refer to the CALTRANS application for a complete description of

the pile driving order of work.

Piles will be driven open-ended by hydraulic or steam hammers.

These are large offshore hammers capable of driving large-diameter,

thick-walled steel pipe piles. No other types of hammers (e.g. drop

hammers, diesel hammers or vibratory hammers) will be used on this

project. According to project specifications, two sizes of hammers are

required. A ``smaller'' hammer having a maximum rated energy of not

less than 500 kilojoules (kJ) but not more than 1,000 kJ will be used

to drive initial segments of the piles. This hammer will be similar in

size to the pile driving hammer that was used for activities associated

with the retrofitting of the San Mateo-Hayward Bridge, also in the Bay.

A larger hammer, having a maximum rated energy of not less than 1,700

kJ will be employed to drive subsequent segments of each pile. No upper

limit is placed on the maximum rated energy of the larger hammer,

however there is little motivation to use a larger hammer than

necessary unless there are no other hammers available at that time.

Furthermore, the piles must be able to support the weight of the anvil,

limiting the size of the hammer that can be used.

The PIDP is expected to take place in late spring 2000. All

necessary equipment for the PIDP will be brought to the project site on

barges, tugboats and other marine vessels. Due to the high cost of the

equipment being used for this project and the nature of pile

installation, work will need to proceed 24 hours a day, 7 days a week

for approximately 20 days barring unforeseen circumstances (i.e. broken

equipment, adverse weather conditions). Actual impact hammering will

only occur for a total of about 12 to 16 hours over the estimated 20

days. Continuous impact hammering would likely occur for a maximum

amount of 2-3 hours at a time. As 3 piles are being driven, this

maximum would only be reached on 3 days out of the 20 days of the PIDP.

The hammer is expected to hit the piles at an average rate of 30-45

blows per minute.

Due to the amount of time needed between driving consecutive pile

segments, it is extremely unlikely that more than two segments will be

driven in a 24-hour period. It is important to note that once the

driving of a pile segment begins it cannot be halted until that segment

has reached its desired depth. This is not only because of the expense

of keeping the equipment idle but also due to the nature of the

predominantly clay soil types underlying the Bay. As piles are driven,

the soil gradually loses resistance. If driving is stopped, the soil

has a chance to regain its strength, and resistance to the pile

increases. This can make it more difficult or even impossible to

continue driving the pile, particularly if the pile tip is in a highly

resistant layer at that point. Consequently, once hammering resumes, it

could potentially take a longer time at increased energy levels. This

could amplify impacts to marine mammals, as they would endure

potentially higher SPLs for longer periods of time. Pile segment

heights and wall thickness have been specially designed for this

project to take the location of highly resistant sediment layers into

account, so that when work is stopped at the desired depths between

segments, the pile tip is never resting in highly resistant sediment

layers. In addition, stopping in the middle of pile driving a segment

may interfere with the goal of understanding the characteristics of

pile driving within this new setting. If pile driving is permitted to

be regularly interrupted, meaningful data regarding how the piles

behave may be difficult to obtain.

Description of the Marine Mammals Affected by the Activity

General information on harbor seals, California sea lions, and

other marine mammal species found in Central California waters can be

found in Barlow et al. (1997, 1998). The marine mammals likely to be

found in the SF-

[[Page 1085]]

OBB area are limited to the California sea lion and harbor seal.

California Sea Lions

While California sea lions are known to have historically used the

Bay, they are rarely observed hauled out in the Bay (Bauer, 1999).

However, since at least 1987, sea lions have been observed occupying

the docks near Pier 39 in San Francisco, about 5.7 km (3.5 mi) from the

project site. The number of sea lions hauled out at Pier 39 ranged from

63 to 737 in 1998 and from 5 to 906 in 1997 (Marine Mammal Center,

Sausalito data). For both years, the lows occurred in June and the

highs occurred in August. Most recently, 831 sea lions were observed on

K dock at Pier 39 in October 1999. While they are present in large

numbers, approximately 85 percent of the animals hauled out at this

site are males, and no pupping has been observed at this site or any

other site in the Bay (Lander pers. comm. to CALTRANS, 1999). At this

time, no other sea lion haul-out sites have been identified in the Bay.

About 90 percent of the U.S. stock breeds on the southern California

Channel Islands, over 483 km (300 mi) from the PIDP site (Schoenherr,

1995; Howorth and Abbott, 1999). Pier 39 has now become a regular haul-

out site for sea lions. The sea lions, most of whom are male, appear at

the site after returning from the Channel Islands at the beginning of

August (Bauer, 1999). Around late winter, sea lions begin to travel

south to the breeding grounds, and numbers at the haul-out site

decline. Lowest numbers of sea lions are usually observed from May

through July. Numbers of sea lions at the haul-out site fluctuate quite

a bit throughout the year and even from one week to the next. For

example, in June of 1998, a maximum of 574 sea lions was observed on

June 7th while a low count of 63 was observed on June 25th

(Lander pers. comm. to CALTRANS, 1999).

While little information is available on the foraging patterns of

California sea lions in the Bay, individual sea lions have been

observed feeding in the shipping channel to the south of YBI on a

fairly regular basis (Grigg pers. comm. to CALTRANS, 1999). Foraging by

sea lions that utilize the Pier 39 haul-out site primarily occurs in

the Bay, where they feed on Pacific herring, northern anchovy and

sardines, among other prey (Hanni, 1995).

Pacific Harbor Seals

Pacific harbor seals are the only species of marine mammal that

breed and bear young in the Bay (Howorth and Abbott, 1999). There are

12 haul-out sites and rookeries in the Bay and of those, only eight are

used by more than a few animals at a time. Only three sites in the Bay

are regularly used by more than 40 harbor seals at any one time; these

are Mowry Slough, located in the South Bay, YBI, and Castro Rocks,

located in the Central Bay (Spencer, 1997). The three closest haul-out

sites to the project location are at YBI, Angel Island, and Castro

Rocks. The most recent aerial harbor seal count, conducted this year by

D. Hanan of the California Department of Fish and Game, found 477

individuals in the Bay (Green pers. comm. to CALTRANS, 1999). It is

important to note that not all harbor seals were counted, as some may

have been under water during the survey.

Harbor seals are present in the Bay year-round and use it for

foraging, resting and reproduction. Peak numbers of hauled-out harbor

seals vary by haul-out site depending on the season. Results of a study

of 39 radio-tagged harbor seals in the Bay found that most active

diving occurred at night and a majority of the diving time was spent in

seven feeding areas in the Bay. The two feeding areas located closest

to the project site are just to the south of YBI and north of Treasure

Island. This study also found that the seals dove for a mean time of

0.50 minutes to 3.33 minutes. Mean surface intervals or the mean time

the seals spent at the surface between dives ranged from 0.33 minutes

to 1.04 minutes. Mean haul-out periods ranged from 80 minutes to 24

hours (Harvey and Torok, 1994).

Pupping season in the Bay begins in mid-March and continues until

about mid-May. Pups nurse for only 4 weeks and mating begins after pups

are weaned. In the Bay, mating occurs from April to July and molting

season is from June until August (Schoenherr, 1995; Kopec and Harvey,

1995).

Haul-Out Sites in the Vicinity of the PIDP

YBI is located in the Central Bay, adjacent to man-made Treasure

Island. The SF-OBB passes through a tunnel on YBI. An important harbor

seal haul-out site is located on a rocky beach on the southwest side of

YBI (Kopec and Harvey, 1995). Work for the PIDP will be performed

approximately 2 km (1.24 mi) from this harbor seal haul-out site,

facing the northwest side of the island.

Although seals haul out year-round on YBI, it is not considered a

pupping site for harbor seals as no births have been observed at the

site. Occasionally, pups have been seen at an average of 1 pup per

year, though more recently, 7 pups were observed at one time in May,

1999 (San Francisco State University unpublished records, 1998-9). In a

study of the haul-out site conducted between 1989 and 1992, males

comprised 83.1 percent of the seals whose gender could be determined

(Spencer, 1997). Peak numbers of harbor seals at this haul-out site

have been observed from November to February. The maximum reported

number of seals hauled out at one time is 344, counted in January 1992

(Kopec and Harvey, 1995). More recently, the number of seals counted at

YBI ranged from 0 to 296 for the period May 1998 to present. The

maximum count of 296 was recorded on January 1999. Mean monthly counts

for the same period range from 14.5 in September 1998 to 107.3 in June

1999 (San Francisco State University, unpublished records 1998-9). The

abundance of harbor seals at this site during the winter months likely

coincides with the presence of spawning Pacific herring near the

island. Re-sightings at the haul-out site indicate long-term usage of

the site (Spencer, 1997).

Angel Island is a small haul-out site located approximately 7.4 km

(4.6 mi) from the project site. A maximum count of 15 seals was

observed in the 1980s and most recently, six harbor seals were seen in

1989. No pupping has been observed at the site.

The next closest haul-out site is approximately 14 km (8.7 mi) away

at Castro Rocks, near the Richmond end of the Richmond- San Rafael

Bridge. The Castro Rocks haul-out site is a recognized pupping site. A

maximum of 176 harbor seals were observed at Castro Rocks in October

1999 (San Francisco State University unpublished records, 1998-9).

Potential Effects on Marine Mammals

It is possible that California sea lions and harbor seals swimming

in the project vicinity may be subject to elevated SPLs that could

produce a temporary shift in the animal's hearing threshold. Pile

driving noise and human activity around the PIDP could also potentially

result in behavioral changes in nearby pinnipeds. California sea lions

and harbor seals may temporarily cease normal activities, such as

feeding, or pop their heads up above water in response to the noise.

They may also be curious and choose to investigate the project site.

However, existing evidence shows that most marine mammals tend to avoid

loud noises (Richardson, pers. comm. to CALTRANS, 1999). It is likely

then that harbor seals and sea lions in the water in the project

vicinity may be temporarily displaced if they choose to avoid the area

in response to the high SPLs. Due to the short-term nature of

[[Page 1086]]

the pile driving (approximately 12 to 16 hours over 20 days) and its

distance from the YBI haul-out site, the PIDP is not expected to result

in long-term behavioral impacts to Bay seals or sea lions.

Based on in-air hammer noise measurements conducted elsewhere, the

average received SPLs were 107 dB re 20 Pa measured

at 10-20 meters (33-66 feet) from the hammer and between 70 dB and 44

dB re 20 Pa at 2,400 meters (7,874 feet or 1.5

miles) from the hammer. While a direct comparison is not possible due

to different atmospheric and geographic conditions, it is anticipated

that in-air noise levels at the YBI haul-out site, located

approximately 2.0 km (1.24 miles) from the project site and physically

shielded by the island, will attenuate to levels insufficient to cause

injury to the seals and sea lions. It is also likely that harbor seals

at this site will not be disturbed by the sound and leave the beach for

the water, although they will most likely hear the pile driving noise.

Consequently, while it is likely that hauled-out marine mammals

will hear the pile driving activities, noise levels are not expected to

adversely impact them. Impact hammering could potentially harass those

harbor seals that are in the water closer to the project site, whether

their heads are above or below the surface. Potential impacts could

include a temporary elevation in hearing threshold and/or changes in

behavior patterns. However, potential harassment would only occur

during those times when piles are being hammered, estimated at

approximately 12 to 16 hours over 20 days.

It is difficult to estimate the number of California sea lions that

could potentially be affected by the PIDP due to the lack of

information on the number of sea lions in the Bay except for the Pier

39 haul-out site. However, assuming the sea lion population at Pier 39

starts to decline in the late winter as the sea lions migrate south to

the rookeries, only a fraction of the animals would be left in the Bay

at the time of the PIDP (late spring 2000). According to the Marine

Mammal Center in Sausalito, the maximum number of sea lions observed at

the Pier 39 haul-out site during the spring and summer seasons was 820

in April 1999. The mean numbers of sea lions observed at Pier 39 during

spring and summer seasons were 340 in 1998 and 453 in 1997 (Lander,

personal communication to CALTRANS, 1999). Because the Pier 39 haul-out

site is located 5.7 km (3.5 mi) away from the project site, only a

fraction of those sea lions left in the Bay at the time of the project

could potentially be in the project vicinity at any one time. Although

California sea lions are known to forage in groups, available evidence

suggests that they are not regularly seen in groups in the Bay waters

near the PIDP site. In surveys conducted from May 1998 to the present,

sea lions have been observed foraging in the shipping channel to the

south of YBI. However, these sea lions are typically alone and do not

seem to be associated with any other sea lions (Grigg, personal

communication 1999). Given this anecdotal evidence, the number of sea

lions expected to be present at the PIDP site during pile driving

activities is expected to be low.

Noise levels from the project are not expected to result in

harassment of the sea lions hauled out at Pier 39 as SPLs would be

expected to attenuate by the time they reach the haul-out site, 5.7

kilometers (3.5 miles) from the project site. As most of the sea lions

observed at Pier 39 are males, and the project will occur during the

time when females and adult males are in waters off southern California

for the breeding and pupping season, it is anticipated that most of the

California sea lions impacted would be subadult males.

Kopec and Harvey (1995) reported harbor seal counts for several

haul-out sites in the Bay for the period 1989-1992.

Peak numbers of harbor seals haul out at YBI in the winter months.

The maximum recorded number of harbor seals observed at YBI is 344,

recorded in January 1992. The PIDP is likely to occur in late spring of

2000. According to Kopec and Harvey (1995), the maximum number of seals

observed at the YBI haul-out site during the pupping season (March-

July) was 127 in 1992. More recently, for the same season, the Richmond

Bridge Harbor Seal Survey reported a maximum count of 213 harbor seals

observed in July 1998 (San Francisco State University, unpub. records

1998-9). Kopec and Harvey reported mean harbor seal numbers of 35.7,

41.1, 63.5 and 65.6 during the pupping seasons (March 15-May 31) of

1989 to 1992, respectively (1995). The mean number of harbor seals

observed during the pupping and molting seasons (March 15 to August 15)

in 1998 and 1999 were 75.2 and 78.4, respectively (San Francisco State

University, unpub. records 1998-9). Keeping in mind that these mean

counts were taken for slightly different periods of time (March-July in

1989-1992 and March-August in 1998-1999) and the number of surveys

taken varies by count, the average of the mean counts is 60.

Mitigation

Based upon a recommendation from NMFS, CALTRANS proposes to

establish a 500-m (1640-ft) radius safety zone around the pile driving

site. The safety zone is intended to include all areas where the

underwater sound pressure levels are anticipated to equal or exceed 180

dB re 1 Pa. Once pile driving begins, SPLs will be recorded at

the 500-m contour. The safety zone radius will then be enlarged or

reduced, depending on the actual recorded SPLs.

Before pile driving of a pile segment begins, NMFS-approved

observers on boats will survey the safety zone to ensure that no marine

mammals are seen within the zone. If marine mammals are found within

the safety zone, pile driving of the segment will be delayed until they

move out of the area. If a marine mammal is seen above water and then

dives below, the contractor will wait 15 minutes and if no marine

mammals are observed in that time it will be assumed that the animal

has moved beyond the safety zone. Harbor seals in the Bay are known to

dive for a mean time of 0.50 minutes to 3.33 minutes (Harvey and Torok,

1994). However, due to the limitations of monitoring from a boat, there

can be no assurance that the safety zone will be devoid of all marine

mammals.

If marine mammals enter the safety zone after pile driving of a

segment has commenced, hammering will continue unabated and marine

mammal observers will monitor and record their numbers and behavior.

For reasons mentioned previously, once the pile driving of a segment

begins it cannot be stopped until that segment has reached its

predetermined depth due to the nature of the sediments underlying the

Bay.

NMFS proposes to restrict actual pile driving to times when the

safety zone can be monitored for the entire 15-minute monitoring period

immediately prior to the start-up of pile driving. Also, in order to

obtain information on the behavioral effects to harbor seals and

California sea lions, NMFS proposes to require that a minimum of 50

percent of the pile driving be scheduled during daylight hours.

Daylight pile driving must include both hammer types.

A 500-m (1640-ft) no-entry buffer zone will be established around

the haul-out site on YBI to minimize the impact of project-related

vessel traffic during the PIDP on marine mammals. This buffer zone will

be established in coordination with the U.S. Coast Guard (USCG). The

exclusion zone will be delineated with USCG-compliant temporary buoys

to insure compliance.

[[Page 1087]]

CALTRANS will establish strict standards on vessel speed for all

project-related crafts traveling in the Bay.

The PIDP is expected to take place in late spring 2000. This timing

would not coincide with the period of peak abundance at the YBI harbor

seal haul-out site (November through February). Although harbor seal

pupping and mating season will be ongoing in the Bay during the PIDP,

YBI is not a known pupping site. Harbor seal molting season in the Bay

begins in June. If the PIDP occurs during the harbor seal molting

season, a greater proportion of harbor seals should be hauled out and,

therefore, not subject to the potentially elevated in-water SPLs from

pile driving.

Finally, CALTRANS proposes to use this demonstration period to test

the effectiveness of potential mitigation techniques. One potential

mitigation measure is an underwater sound barrier based on the noise-

attenuating properties of air bubbles in water. At least two

experimental techniques for creating underwater sound barriers will be

tested by CALTRANS. Underwater SPLs will be recorded at various

distances from pile driving activities in order to assess which

measures, if any, prove practical and effective in reducing sound

pressure levels.

Monitoring

Monitoring of the safety zone will be conducted during all active

pile driving. Monitoring of the safety zone will be conducted by a

minimum of three qualified observers. The observers will begin

monitoring at least 30 minutes prior to startup of the pile driving.

Observers will likely conduct the monitoring from small boats, as

observations from a higher vantage point (such as the SF-OBB) may not

be practical.

Observations will be made using binoculars during daylight hours.

For operations at night, infrared or image intensifying equipment will

be used. In addition to monitoring from boats, monitoring of the YBI

haul-out will be conducted on land during all active pile driving. Data

on all observations will be recorded and will include items such as

species, numbers, time of observation, location, behavior, etc.

Both underwater and airborne SPL measurements will be made.

Underwater Sound Monitoring

Waterborne sound from the pile driving will be measured at

approximately four locations. These locations will typically be in some

combination of: (i) close to the pile driving activity, (ii) two mid-

point locations, and (iii) one distant location. Each measuring system

will consist of a hydrophone with charge type conditioning amplifier

connected to a sound level readout device and an instrumentation-grade

digital audio tape (DAT) recorder. ``Real-time'' amplitude DAT

measurements of underwater sound levels will be provided. The

hydrophone will be deployed from a skiff to an appropriate depth at

each location. A portable geostationary positioning system (GPS) unit

will document the location coordinates of the skiff. It is anticipated

that the sound level and frequency spectrum of the recorded noise

signals will also be analyzed in a laboratory subsequent to the test.

Airborne Sound Monitoring

Airborne sound from the pile driving will be measured at

approximately four locations that are coincident with the underwater

measurement locations (i.e., typically a combination of: (i) close to

the pile driving activity, (ii) two mid-point locations, and (iii) one

distant location). In addition, airborne sound will also be measured at

Yerba Buena Island, as close as practicable to the haul-out site. Each

measuring system will consist of a Type 1 Sound Level Meter (SLM)

connected to an instrumentation-grade DAT recorder. ``Real-time''

amplitude measurements of airborne sound levels will be provided. The

SLM will be equipped with a windscreen and tripod mounted on a skiff at

approximately 1.2 meters above water level. As previously stated, a

portable GPS unit will document the location coordinates of the skiff.

It is anticipated that the sound level and frequency spectrum of the

recorded noise signals will be analyzed in a laboratory subsequent to

the test.

Reporting

CALTRANS proposes to notify NMFS prior to the initiation of the

PIDP, and coordination with NMFS will occur on a weekly basis, or more

often, as necessary. NMFS will be informed of the initial sound

pressure levels measurements taken at the 500-m (1640-ft) contour and

the final safety-zone radius established. Monitoring reports will be

faxed to NMFS on a daily basis. The daily report will include species

and numbers of marine mammals observed, time and location of

observation, behavior. In addition the report will include an estimate

of the number of California sea lions and Pacific harbor seals that may

have been harassed as a result of the pile driving activities.

CALTRANS will provide NMFS with a final report detailing the

monitoring protocol, a summary of the data recorded during monitoring,

an estimate of the numbers of marine mammals that may have been

harassed due to pile driving, and conclusions drawn from measurements

with and without the attenuation measures.

Preliminary Conclusions

Based on the previous discussion, NMFS has preliminarily determined

that the PIDP may unintentionally cause the harassment of California

sea lions and Pacific harbor seals. Although CALTRANS has requested an

authorization for Level B harassment, as a result of a behavioral

modification to avoid either pile driving noise or human activity, NMFS

notes that, on occasion, monitoring the safety zone may not be 100

percent effective. As a result, some harbor seals or California sea

lions, while underwater in the vicinity of the PIDP, may incur levels

above 180 dB re 1 Pa. At and above an SPL of this level,

marine mammals may incur a temporary threshold shift (TTS) in hearing,

lasting from a few minutes to a few hours. NMFS considers TTS to

constitute Level A harassment (see Sec. 216.3 for a definition of Level

A and Level B harassment).

[[Page 1088]]

The PIDP is expected to have no more than an insignificant impact

to marine mammals or their habitat. Harbor seals on YBI are commonly

subjected to high levels of disturbance, primarily from watercraft,

especially during the summer, when the numbers of small boats, jet

skis, kayaks, etc. in the Bay increase. Abandonment of the haul-out

site is not anticipated as sound levels from pile driving, both in

water and in air, are expected to attenuate to sufficiently low levels

by the time the SPLs reach the YBI haulout site. Although harbor seal

pups have been observed at the YBI haul-out site, it is not a

recognized pupping site and, therefore, no significant impacts on

species recruitment are anticipated. Other haul-out sites for sea lions

and harbor seals area are at a sufficient distance from the project

site that they will not be affected.

Proposed Authorization

NMFS proposes to issue an incidental harassment authorization to

CALTRANS for the possible harassment of small numbers of harbor seals

and California sea lions incidental to a PIDP at the SF-OBB, provided

the previously mentioned mitigation, monitoring and reporting

requirements are incorporated. NMFS has preliminarily determined that

the proposed activities would result

in the harassment (as defined in the MMPA) of only small numbers of

harbor seals and California sea lions and will have no more than a

negligible impact on these marine mammal stocks.

Information Solicited

NMFS requests interested persons to submit comments, information,

and suggestions concerning this request (see ADDRESSES).

Dated: December 28, 1999.

Ann D. Terbush,

Acting Director, Office of Protected Resources, National Marine

Fisheries Service.

[FR Doc. 00-405 Filed 1-6-00; 8:45 am]

BILLING CODE 3510-22-F