2024-23797. Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Pacific Gas & Electric Sediment Remediation Project, San Francisco Bay

Table 1—Schedule of In-Water Construction

Type of pile	Total number of pile installation/ removal	Number of piles installed/removed per day	Days of pile driving or removal
Turbidity Curtain (Steel H-Piles or Steel Shell Pile ≤24 inches)	40 (20 installed, 20 removed)	4	10
RWF Temporary Relocation (24-inch and 36-inch Steel Shell Piles)	40 (20 installed, 20 removed)	4	10
Sediment Pin Installation (14- to 16-inch timber or plastic)	120 (installation only)	8	15
Hydroacoustic Data Collection Piles (18-inch composite)	20 (10 installed, 10 removed)	2	10
( print page 83461)
Total	180		45
Total (+10% buffer)		* 50
* Rounded to maximum number of full days

Description of Marine Mammals

A description of the marine mammals in the area of the activities for which authorization of take is proposed here, including information on abundance, status, distribution, and hearing, may be found in the notice of the proposed IHA (88 FR 82836, November 27, 2023) for the initial authorization. NMFS has reviewed the 2023 draft Stock Assessment Reports (SARs), information on relevant Unusual Mortality Events, and other scientific literature, and determined there is no new information that affects which species or stocks have the potential to be affected or the pertinent information in the Description of the Marine Mammals in the Area of Specified Activities contained in the supporting documents for the initial IHA. The abundance estimate for the Eastern stock of the Steller sea lion has decreased from 43,201 to 36,308 according to the 2023 draft SAR (Young et al., 2024), but this does not change estimated take numbers or influence the findings made in support of the initial IHA.

Potential Effects on Marine Mammals and Their Habitat

A description of the potential effects of the specified activity on marine mammals and their habitat for the activities for which an authorization of incidental take is proposed here may be found in the notice of the proposed IHA (88 FR 82836, November 27, 2023) for the initial authorization. NMFS has reviewed recent draft SARs, information on relevant Unusual Mortality Events, and other scientific literature, and determined that there is no new information that affects our initial analysis of impacts on marine mammals and their habitat.

Estimated Take

A detailed description of the methods and inputs used to estimate take for the specified activity is found in the notices of the proposed and final IHAs (88 FR 82836, November 27, 2023; 89 FR 5865, January 30, 2024) for the initial authorization. The only changes PG&E proposes to make for the renewal IHA is to add 2 24-inch steel shell piles and 2 36-inch steel shell piles, resulting in a total of 10 of each piles, for installation and removal in the RWF Relocation portion of the project. The source levels, days of operation, and marine mammal occurrence data applicable to this authorization remain unchanged from the previously issued IHA. Similarly, the stocks taken, methods of take, and types of take remain unchanged from the previously issued IHA, as do the number of takes, which are indicated below in table 2.

Table 2—Summary of Marine Mammal Takes by Species

Species	Stock	Proposed Level B harassment takes	Stock abundance	Percent of stock (%)
Harbor seal	California	1,000	30,968	3.2
Northern elephant seal	California breeding	25	187,386	0.01
California sea lion	United States	9,550	257,606	3.7
Northern fur seal	California; Eastern North Pacific	5	14,050; 626,618	0.04; 0.001
Steller sea lion	Eastern	5	36,308	0.01
Bottlenose dolphin	Coastal California	25	453	5.5
Harbor porpoise	San Francisco-Russian River	100	7,777	1.3

On May 3, 2024, NMFS published (89 FR 36762) and solicited public comment on its draft Updated Technical Guidance ( https://www.fisheries.noaa.gov/​s3/​2024-05/​NMSFAcousticGuidance-DraftTECHMEMOGuidance-3.0-FEB-24-OPR1.pdf), which includes updated thresholds and weighting functions to inform auditory injury estimates, and is intended to replace the 2018 Technical Guidance referenced in the notices for the proposed and final IHA (88 FR 82836, November 27, 2023; 89 FR 5865, January 30, 2024), once finalized. The public comment period ended on June 17, 2024, and although the Updated Technical Guidance is not final, NMFS expects the Updated Technical Guidance to represent the best available science once it is. In consideration of the best available science, NMFS has conducted calculations using the draft Updated Technical Guidance and NMFS draft optional user spreadsheet, using the source levels and spreadsheet inputs provided in the notices for the proposed and final IHAs (88 FR 82836, November 27, 2023; 89 FR 5865, January 30, 2024), for the purpose of understanding how Level A harassment (auditory injury) zones would change from the initial IHA. The relevant draft updated weighting functions may be found in the executive summary of the draft Updated Technical Guidance, on page 3. The draft updated marine mammal hearing groups and draft updated thresholds can be found in tables 3 and 4. ( print page 83462)

Table 3—Marine Mammal Hearing Groups

[NMFS, 2024]

Hearing group	Generalized hearing range *
Low-frequency (LF) cetaceans (baleen whales)	7 Hz to 36 kHz.
High-frequency (HF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales)	150 Hz to 160 kHz.
Very High-frequency (VHF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. australis)	200 Hz to 165 kHz.
Phocid pinnipeds (PW) (underwater) (true seals)	40 Hz to 90 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions and fur seals)	60 Hz to 68 kHz.
* Represents the generalized hearing range for the entire group as a composite ( i.e., all species within the group), where individual species' hearing ranges may not be as broad. Generalized hearing range chosen based on ~65-dB threshold from composite audiogram, previous analysis in NMFS, 2018, and/or data from Southall et al., 2007; Southall et al., 2019. Additionally, animals are able to detect very loud sounds above and below that “generalized” hearing range.

Table 4—Onset of Auditory Injury (AUD INJ)

[NMFS, 2024]

Hearing group	AUD INJ onset thresholds * (received level)
	Impulsive	Non-impulsive
Low-Frequency (LF) Cetaceans	Cell 1:Lp ,0-pk,flat : 222 dB; Lp ,E,p,LF,24h : 183 dB	Cell 2:LE, p ,LF,24h : 197 dB.
High-Frequency (HF) Cetaceans	Cell 3:Lp ,0-pk,flat : 230 dB; LE, p ,HF,24h : 193 dB	Cell 4:LE, p ,HF,24h : 201 dB.
Very High-Frequency (VHF) Cetaceans	Cell 5:Lp ,0-pk,flat : 202 dB; LE, p ,VHF,24h : 159 dB	Cell 6:LE, p ,VHF,24h : 181 dB.
Phocid Pinnipeds (PW) (Underwater)	Cell 7:Lp ,0-pk.flat : 223 dB; LE, p ,PW,24h : 183 dB	Cell 8:LE, p ,PW,24h : 195 dB.
Otariid Pinnipeds (OW) (Underwater)	Cell 9:Lp ,0-pk,flat : 230 dB; LE, p ,OW,24h : 185 dB	Cell 10:LE, p ,OW,24h : 199 dB.
* Dual metric thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds are recommended for consideration.
Note: Peak sound pressure level ( Lp ,0-pk ) has a reference value of 1 μPa, and weighted cumulative sound exposure level ( LE, p ) has a reference value of 1μPa2 s. In this table, thresholds are abbreviated to be more reflective of International Organization for Standardization standards (ISO, 2017). The subscript “flat” is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized hearing range of marine mammals ( i.e., 7 Hz to 165 kHz). The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The weighted cumulative sound exposure level thresholds could be exceeded in a multitude of ways ( i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate the conditions under which these thresholds will be exceeded.

NMFS has also considered whether modifications to mitigation requirements, i.e., shutdown zones, would be appropriate in light of the draft Updated Technical Guidance. Based on the outcome of these analyses using the draft Updated Technical Guidance, alternate Level A harassment zones are presented in table 5, as well as the Level A harassment zones from the initial IHA, based on the 2018 Technical Guidance, for comparison. Proposed mitigation zones, in consideration of the draft Updated Technical Guidance where appropriate, are discussed in the Description of Proposed Mitigation, Monitoring and Reporting Measures section.

Although some estimated Level A harassment zones have increased using the 2024 guidance, consistent with the initial IHA no Level A harassment takes are anticipated, because PG&E proposes to change the shutdown zones accordingly and consistent with the intent of the measures prescribed through the initial IHA, as discussed in Description of Proposed Mitigation, Monitoring and Reporting Measures section.

Table 5—Level A Harassment Zones Using 2018 Technical Guidance and Draft 2024 Technical Guidance

Pile type and method	Level A harassment zones using 2018 technical guidance (m)				Level A harassment zones using draft 2024 technical guidance (m)
	HF Cetacean a	VHF Cetacean b	Phocids	Otariids	HF Cetacean	VHF Cetacean	Phocids	Otariids
Hydroacoustic Data Collection
18-inch Composite, Impact	<1	19	9	<1	2	25	14	5
18-inch Composite, Vibratory	<1	6	3	1	1	2	3	1
Turbidity Curtain
Steel H-Pile, Vibratory	0	<1	<1	<1	<1	<1	<1	<1
Steel Shell Pile ≤24-inch, Vibratory	<1	4	2	1	<1	2	3	1
RWF Temporary Relocation Piles
Steel Shell Pile 24-inch, Vibratory	<1	4	2	<1	<1	2	3	1
Steel Shell Pile 24-inch, Impact, Attenuated c	11	351	158	12	37	454	261	97
( print page 83463)
Steel Shell Pile ≤36 inch, Vibratory	3	28	14	2	13	27	42	14
Sediment Pins
14 to 16-inch Timber, Vibratory	2	23	10	1	8	17	27	9
14 to 16-inch Timber, Impact	<1	14	6	<1	2	18	10	4
14 to 16-inch Composite, Vibratory	<1	6	3	<1	2	4	7	2
14 to 16-inch Composite, Impact	<1	9	4	<1	1	11	7	2
a  In the 2018 guidance and initial IHA, HF cetaceans were referred to as MF (mid-frequency) cetaceans
b  In the 2018 guidance and initial IHA, VHF cetaceans were referred to as HF (high-frequency) cetaceans.
c  5-dB reduction in sound due to use of bubble curtain assumed.

Description of Proposed Mitigation, Monitoring and Reporting Measures

The proposed mitigation, monitoring, and reporting measures included as requirements in this authorization are nearly identical to those included in the Federal Register notice announcing the issuance of the initial IHA (89 FR 5865, January 30, 2024), and the discussion of the lest practicable adverse impact included in that document and the notice of the proposed IHA (88 FR 782836, November 27, 2023) remain accurate. Consistent with the mitigation required through the initial IHA, shutdown zones proposed for the renewal IHA will be based on the largest Level A harassment zone for each pile size/type and driving method, as updated using the draft 2024 Technical Guidance rather than the 2018 Technical Guidance. The zones are calculated identically to those presented in the notice of the proposed IHA (88 FR 82836, November 27, 2023), with reference to the updated Technical Guidance. The following mitigation, monitoring, and reporting measures are proposed for this renewal:

• PG&E must shut down construction operations if a marine mammal comes within 10 m of construction activity to avoid direct physical interaction with marine mammals;
• PG&E must establish shutdown zones for all pile driving activities. Shutdown zones are based on the largest Level A harassment zone for each pile size/type and driving method;
• PG&E must shut down during active pile driving if marine mammals approach shutdown zones (see table 6);
• NMFS-approved protected species observers (PSOs) must be used to monitor the full shutdown zones and as much of the Level B harassment zone as possible;
• PSOs must monitor the shutdown zones for at least 30 minutes prior to pile driving, throughout pile driving, and 30 minutes after;
• If marine mammals are found within the shutdown zone, pile driving must be delayed until the animal has moved out of the shutdown zone;
• PG&E must shut down if any species for which take has not been authorized, or a species for which take has been authorized but the authorized take numbers have been met, approaches or enters the Level B harassment zones;
• Should environmental conditions deteriorate such that marine mammals within the entire shutdown zone would not be visible (e.g., fog, heavy rain), pile driving must be delayed until observers are confident marine mammals within the shutdown zone could be detected;
• PG&E must implement impact pile driving soft starts whereby hammer energy is gradually ramped up;
• A bubble curtain must be used during impact pile driving of steel piles;
• PG&E must submit a draft marine mammal monitoring report to NMFS within 90 days after the completion of pile driving activities or 60 calendar days prior to the requested issuance of any subsequent IHA for construction activity at the same location, whichever comes first. A final report must be prepared and submitted within 30 calendar days following receipt of any NMFS comments on the draft report; and
• All injured or dead marine mammals must be reported to the Office of Protected Resources and to the West Coast regional stranding network.

Table 6—Proposed Updated Shutdown Zones

Pile type and method	Shutdown zone for all species (m)	Change from initial IHA
Hydroacoustic Data Collection
18-inch Composite, Impact	30	Increased 10 m.
18-inch Composite, Vibratory Removal	10	No change.
Turbidity Curtain
Steel H-Pile, Vibratory Installation and Removal	10	No change.
Steel Shell Pile ≤24 inch, Vibratory Installation and Removal	10	No change.
RWF Relocation Piles
Steel Shell Pile 24 inch, Vibratory Installation and Removal	10	No change.
Steel Shell Pile 24 inch, Impact, Attenuated	450	Increased 90 m.
( print page 83464)
Steel Shell Pile 36 inch, Vibratory	40	Increased 10 m.
Sediment Pins
14- to 16-inch Timber, Vibratory	30	No change.
14- to 16-inch Timber, Impact	20	No change.
14- to 16-inch Composite, Vibratory	10	No change.
14- to 16-inch Composite, Impact	20	No change.