# Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to In-Water Construction at Two Ferry Facilities on Bainbridge Island, Washington > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2022-17141 ## Record - **Collection:** Federal Register - **Document type:** Notice - **Published:** August 10, 2022 - **Citation:** 87 FR 48623 ## Text DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration [RTID 0648-XC114] Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to In-Water Construction at Two Ferry Facilities on Bainbridge Island, Washington AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice; proposed incidental harassment authorization (IHA); request for comments on proposed authorization and possible renewal. SUMMARY: NMFS has received a request from the Washington State Department of Transportation Ferries Division (WSDOT) for authorization to take marine mammals incidental to two in-water construction projects on Bainbridge Island, Washington: the Bainbridge Island Ferry Terminal Overhead Loading Replacement Project and Eagle Harbor Maintenance Facility Slip F Improvement Project. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an IHA to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, one-year renewal that could be issued under certain circumstances and if all requirements are met, as described in Request for Public Comments at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization and agency responses will be summarized in the final notice of our decision. DATES: Comments and information must be received no later than September 9, 2022. ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service and should be submitted via email to ITP.Fowler@noaa.gov. Instructions: NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. Comments, including all attachments, must not exceed a 25-megabyte file size. All comments received are a part of the public record and will generally be posted online at www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying information ( e.g., name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information. FOR FURTHER INFORMATION CONTACT: Amy Fowler, Office of Protected Resources, NMFS, (301) 427-8401. Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems accessing these documents, please call the contact listed above. SUPPLEMENTARY INFORMATION: Background The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq. ) direct the Secretary of Commerce (as delegated to NMFS) 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 proposed or, if the taking is limited to harassment, a notice of a proposed incidental harassment 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) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in shorthand as “mitigation”); and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth. The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below. National Environmental Policy Act To comply with the National Environmental Policy Act of 1969 (NEPA; 42 U.S.C. 4321 et seq. ) and NOAA Administrative Order (NAO) 216-6A, NMFS must review our proposed action ( i.e., the issuance of an IHA) with respect to potential impacts on the human environment. This action is consistent with categories of activities identified in Categorical Exclusion B4 (IHAs with no anticipated serious injury or mortality) of the Companion Manual for NOAA Administrative Order 216-6A, which do not individually or cumulatively have the potential for significant impacts on the quality of the human environment and for which we have not identified any extraordinary circumstances that would preclude this categorical exclusion. Accordingly, NMFS has preliminarily determined that the issuance of the proposed IHA qualifies to be categorically excluded from further NEPA review. We will review all comments submitted in response to this notice prior to concluding our NEPA process or making a final decision on the IHA request. Summary of Request On February 15, 2022, NMFS received a request from WSDOT for an IHA to take marine mammals incidental to the Bainbridge Island Ferry Terminal Overhead Loading Replacement Project (the Bainbridge Project) and Eagle Harbor Maintenance Facility Slip F Improvement Projects (the Eagle Harbor Project) in Bainbridge Island, Washington. The application was deemed adequate and complete on July 25, 2022. WSDOT's request is for take of 12 species of marine mammal by Level B harassment and, for a subset of these species (harbor seal ( Phoca vitulina ), harbor porpoise ( Phocoena phocoena ), and Dall's porpoise ( Phocoenoides dalli )), Level A harassment. Neither WSDOT nor NMFS expect serious injury or mortality to result from this activity and, therefore, an IHA is appropriate. Description of Proposed Activity Overview The Washington State Department of Transportation (WSDOT) Ferries Division (WSF) operates and maintains 19 ferry terminals and one maintenance facility, all of which are located in either Puget Sound or the San Juan Islands. Two projects are proposed to be conducted: replacement of the Bainbridge Island Ferry Terminal overhead loading structure, and improvement of the Eagle Harbor Maintenance Facility Slip F. Both of the projects are located within Eagle Harbor on Bainbridge Island, Washington, would be completed within the same in-water work season, would have overlapping ensonified areas, and use the same datasets to estimate marine mammal takes. Therefore, WSDOT has submitted one application for a single IHA to cover both projects. The purpose of the Bainbridge Project is to replace the seismically vulnerable timber trestle and fixed steel portions of the overhead loading structure at the Bainbridge Island Ferry Terminal. The purpose of the Eagle Harbor Project is to improve the maintenance efficiency of the facility. The facility has six vessel slips whose purpose is to maintain the Washington State Ferry (WSF) system's vessels. Dates and Duration Due to in-water work timing restrictions established by NMFS and the U.S. Army Corps of Engineers, construction in the projects area is limited each year from August 1 through February 15. Both the Bainbridge Project and the Eagle Harbor Project would be constructed during the August 1, 2022 to February 15, 2023 in-water work season. For the Bainbridge Project, in-water construction is expected to occur on up to 57 days (Table 1). For the Eagle Harbor Project, in-water construction is expected to occur on up to 31 days (Table 2). Specific Geographic Region Both projects are located within Eagle Harbor on Bainbridge Island, Washington, approximately 9 miles (mi; 14.5 kilometers (km)) west of Seattle, Washington. The Eagle Harbor Maintenance Facility is approximately 1/4 mi (0.4 km) southwest of the Bainbridge Island Ferry Terminal. Eagle Harbor contains a mix of commercial docks, public marinas, private docks, and undeveloped waterfront properties. The harbor extends 2 mi (1.2 km) west from the mouth of the harbor, which is approximately 900 feet (ft; 274.3 meters (m)) wide and is bounded by Wing Point to the north and Bill Point to the south. A large underwater sand bar extends to the southeast from Wing Point. Water depths within Eagle Harbor range are up to 50 ft (15.2 m) but outside the harbor, water depths between Bainbridge Island and Seattle can be over 700 ft (213.4 m). EN10AU22.251 Detailed Description of Specific Activity Bainbridge Project The existing overhead loading fixed walkway at the Bainbridge Island Ferry Terminal consists of two major components: a timber trestle, constructed in 1972, which is approximately 345 ft (105.2 m) long and supported on timber batter piles; and a steel truss, constructed in 1988, which is approximately 78 ft (23.8 m) long and supported on a concrete shaft at each end. The walkway is elevated approximately 40 ft (12.2 m) above ground. The proposed project elements for the Bainbridge Project include: 1. Installation of temporary work platforms: two temporary work platforms would support construction equipment. A total of 31 24-inch (in) steel pipe piles would support the structures, which would be installed first using a vibratory hammer to within 5 ft (1.5 m) of tip elevation, and then driven with an impact hammer to verify bearing capacity. 2. Installation of temporary walkway: a temporary walkway would be constructed to maintain overhead loading operations while the new walkway is constructed. This would allow the inshore portion of the existing walkway to be demolished so the new walkway can be constructed. The offshore portion of the existing walkway would remain to allow passenger loading until the new walkway is completed. The temporary walkway would be supported on four 24-inch diameter steel piles, which would be installed first using a vibratory hammer to within 5 ft (1.5 m) of tip elevation, and then driven with an impact hammer to verify bearing capacity. 3. Installation of new permanent walkway: the new walkway would be supported by 14 30-in and 12 36-in steel pipe piles, which would be installed first using a vibratory hammer to within 5 ft (1.5 m) of tip elevation, and then driven with an impact hammer to verify bearing capacity. 4. Removal of existing overhead loading walkway: the existing overhead loading walkway, including 76 creosote-treated 12-in timber piles and one 4.5 ft (1.4 m) diameter concrete drill shaft, would be removed. The piles would be removed using a vibratory hammer and the concrete drill shaft would be removed by cutting it with a saw at the mudline. 5. Removal of temporary walkway and work platform: after the new walkway is constructed, all piles associated with the temporary walkway and work platform would be removed with a vibratory hammer. The construction schedule would be coordinated to allow work to occur around ferry boats that may be present in the Bainbridge Island Ferry Terminal slips. Table 1—Proposed Pile Driving for the Bainbridge Project Project element Pile size and type Install or remove Method Number of piles Duration per pile (minutes) Piles per day Duration (days) Temporary work platform and temporary walkway 24-in Steel Install Vibratory 39 30 4 10 Impact 39 30 4 10 Remove Vibratory 39 30 4 10 New Overhead Loading Structure 24-in Steel Install Vibratory 6 30 2 3 Impact 6 30 2 3 30-in Steel Install Vibratory 4 30 2 2 Impact 4 30 2 2 36-in Steel Install Vibratory 12 30 2 6 Impact 12 30 2 6 Old Overhead Loading Structure Removal 12-in Timber Remove Vibratory 76 15 15 5 Total Temporary Piles Installed and Removed 39 Total Permanent Piles Installed 26 Total Timber Piles Removed 76 Total Duration (days) 57 Eagle Harbor Project The last seven vessels built for the WSF fleet have evacuation slides on the passenger deck. These require the use of a vehicle drive-on slip to allow changing out these slides. Currently, only two of the six slips are vehicle drive-on slips. This results in delays when more than two vessels are undergoing maintenance. A new vehicle drive-on slip would be constructed to reduce maintenance delays, and provide more flexibility in accomplishing the various maintenance activities on the vessels that is crucial to making the WSF system as reliable as possible. The proposed project elements for the Eagle Harbor Project include: 1. Trestle and transfer span: The vehicle transfer span is the link for vehicles to load and unload from the fixed trestle to the vehicle deck of the ferry vessel. At Eagle Harbor, the existing Slip F gangplank system would be replaced with a new pile supported trestle and a transfer span adjustable with a mechanical system. The new trestle would be approximately 15-ft (4.6 m) wide and 80 ft (24.4 m) long, and will be supported by nine 24-in steel pipe piles and two 36-in steel pipe piles which would each be installed first using a vibratory hammer to within 5 ft (1.5 m) of tip elevation, and then driven with an impact hammer to verify bearing capacity. 2. Wingwalls and dolphins: The existing pair of timber dolphins would be replaced with a new pair of steel wingwalls. Two new fixed pile dolphins would be constructed adjacent to the Trask Pier. The wingwalls design would consist of four 36-inch diameter steel reaction piles and two 36-inch diameter fender piles. Two fixed dolphins would be constructed adjacent to the Trask Pier to provide protection to the pier and mooring lines for tie-up. The dolphin design would consist of four 30-inch diameter steel reaction piles and one 36-inch diameter fender pile. Wingwall and dolphin piles would be installed using a vibratory hammer only. 3. Removal of timber walkway, timber dolphins, and U-float: the project would also include the removal of a currently existing timber walkway/trestle, four timber pile dolphins, and a U-float. The timber trestle removal includes 52 12-inch diameter timber piles, the four dolphins include a total of 134 12-inch diameter timber piles, and the U-float consists of four 18-inch diameter steel piles, all of which would be removed using a vibratory hammer. Table 2—Proposed Pile Driving for the Eagle Harbor Project Project element Pile size and type Install or remove Method Number of piles Duration per pile (minutes) Duration (hours) Rate per day Duration (days) Timber Walkway Pile Removal 12-in Timber Remove Vibratory 52 15 13 15 4 Timber Dolphin Removal 12-in Timber Remove Vibratory 134 15 33.5 15 9 Temporary Relocated Float 18-in Steel Install Vibratory 4 30 4 4 1 Remove 4 30 3 4 1 U-Float Removal 18-in Steel Remove Vibratory 4 30 4 4 1 Trestle and Transfer Span 24-in Steel Install Vibratory 9 30 4.5 4 3 Impact 9 30 4.5 3 3 36-inSteel Install Vibratory 2 30 1 4 1 Impact 2 30 1 3 1 Wingwall 30-in Steel Install Vibratory 8 30 4 4 2 36-in Steel Install Vibratory 4 30 2 4 1 Intermediate Dolphin 30-in Steel Install Vibratory 4 30 2 4 1 36-in Steel Install Vibratory 1 30 5 4 1 Outer Dolphin 30-in Steel Install Vibratory 4 30 2 4 1 36-in Steel Install Vibratory 2 30 1 4 1 Total Piles Removed 194 Total Piles Installed 38 Total Duration (days) 31 Proposed mitigation, monitoring, and reporting measures are described in detail later in this document (please see Proposed Mitigation and Proposed Monitoring and Reporting). Description of Marine Mammals in the Area of Specified Activities Sections 3 and 4 of the application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history of the potentially affected species. NMFS fully considered all of this information, and we refer the reader to these descriptions, incorporated here by reference, instead of reprinting the information. Additional information regarding population trends and threats may be found in NMFS' Stock Assessment Reports (SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments ) and more general information about these species ( e.g., physical and behavioral descriptions) may be found on NMFS' website ( https://www.fisheries.noaa.gov/find-species). Table 3 lists all species or stocks for which take is expected and proposed to be authorized for this activity, and summarizes information related to the population or stock, including regulatory status under the MMPA and Endangered Species Act (ESA) and potential biological removal (PBR), where known. PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS' SARs). While no serious injury or mortality is anticipated or authorized here, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species and other threats. Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS' stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All managed stocks in this region are assessed in NMFS' U.S. Pacific and Alaska SARs. All values presented in Table 3 are the most recent available at the time of publication and are available in the 2020 SARs (Carretta et al., 2021, Muto et al., 2021) and draft 2021 SARs (available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports ). Table 3—Species Likely Impacted by the Specified Activities Common name Scientific name Stock ESA/MMPA status; strategic (Y/N) 1 Stock abundance (CV, N min , most recent abundance survey) 2 PBR Annual M/SI 3 Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) Family Eschrichtiidae: Gray whale Eschrichtius robustus Eastern N Pacific -, -, N 26,960 (0.05, 25,849, 2016) 801 131 Family Balaenopteridae (rorquals): Minke whale Balaenoptera acutorostrata California/Oregon/Washington -, -, N 915 (0.792, 509, 2018) 4.1 ≥0.59 Superfamily Odontoceti (toothed whales, dolphins, and porpoises) Family Delphinidae: Long-Beaked Common Dolphin Delphinus capensis California -, -, N 83,379 (0.216, 69,636, 2018) 668 ≥29.7 Bottlenose Dolphin Tursiops truncatus California Coastal -, -, N 453 (0.06, 346, 2011) 2.7 ≥2.0 Pacific White-Sided Dolphin Lagenorhynchus obliquidens California/Oregon/Washington -, -, N 34,999 (0.222, 29,090, 2018) 279 7 Killer Whale Orcinus orca West Coast Transient -, -, N 349 4 (N/A, 349, 2018) 3.5 0.4 Family Phocoenidae (porpoises): Harbor Porpoise Phocoena phocoena Washington Inland Waters -, -, N 11,233 (0.37, 8,308, 2015) 66 ≥7.2 Dall's Porpoise Phocoenoides dalli California/Oregon/Washington -, -, N 16,498 (0.61, 10,286, 2019) 99 ≥0.66 Order Carnivora—Superfamily Pinnipedia Family Otariidae (eared seals and sea lions): California Sea Lion Zalophus californianus U.S. -, -, N 257,606 (N/A, 233,515, 2014) 14,011 >320 Steller Sea Lion Eumetopias jubatus Eastern -, -, N 43,201 5 (see SAR, 43,201, 2017) 2,592 112 Family Phocidae (earless seals): Harbor Seal Phoca vitulina Washington Northern Inland Waters -, -, N 11,036 6 (UNK, UNK, 1999) UND 9.8 Northern Elephant Seal Mirounga angustirostris California Breeding -, -, N 187,386 (N/A, 85,369, 2013) 5,122 13.7 1 ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. 2 NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. 3 These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined ( e.g., commercial fisheries, ship strike). Annual mortality/serious injury (M/SI) often cannot be determined precisely and is in some cases presented as a minimum value or range. 4 Based on counts of individual animals identified from photo-identification catalogues. Surveys for abundance estimates of these stocks are conducted infrequently. 5 Best estimate of pup and non-pup counts, which have not been corrected to account for animals at sea during abundance surveys. 6 The abundance estimate for this stock is greater than eight years old and is therefore not considered current. PBR is considered undetermined for this stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available information for use in this document. As indicated above, all 12 species (with 12 managed stocks) in Table 3 temporally and spatially co-occur with the activity to the degree that take is reasonably likely to occur. While humpback whales ( Megaptera novaeangliae ) and killer whales from the Southern Resident stock are known to occur in Puget Sound, in consideration of the proposed requirements described in the Proposed Mitigation and Proposed Monitoring and Reporting sections of this notice, WSDOT has determined that take of these species is unlikely to occur and has therefore not requested take of humpback whales or Southern Resident killer whales. NMFS has concurred with this determination and no take of these species is anticipated or proposed to be authorized. Gray Whale Gray whales generally spend the summer and fall in Arctic feeding grounds and winter to early spring in Mexican breeding areas. Between October and February, the species migrates south along the U.S. West Coast, returning north between February and July (Carretta et al., 2021). A subpopulation of the Eastern North Pacific stock, referred to as the Pacific Coast Feeding Group (PCFG), remains along the Washington and Oregon coast to feed for extended periods while the rest of the stock continues along their migratory path (Calambokidis et al., 2018). Occurrence of gray whales in Puget Sound has been steadily increasing in recent years and is generally highest between February and May. Most gray whales remain further north in Puget Sound, concentrating in the waters around Whidbey Island, but some venture south, including into Elliott Bay near WSDOT's proposed activities (Orca Network, 2021). During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a total of 4 gray whales were observed, with a maximum of 1 individual observed on a single day. Biologically Important Areas (BIAs) for feeding gray whales along the coasts of Washington, Oregon, and California have been identified, including northern Puget Sound, Northwestern Washington, and Grays Harbor in Washington, Depoe Bay and Cape Blanco and Orford Reef in Oregon, and Point St. George in California; most of these areas are of importance from late spring through early fall (Calambokidis et al., 2015). BIAs have also been identified for migrating gray whales along the entire coasts of Washington (including the inland waters of Puget Sound), Oregon, and California; although most whales travel within 10 km from shore, the BIAs were extended out to 47 km from the coastline (Calambokidis et al., 2015). On May 30, 2019, NMFS declared an unusual mortality event (UME) for gray whales after elevated numbers of strandings occurred along the U.S. west coast. As of January 7, 2022, a total of 502 stranded gray whales have been reported, including 256 in the United States (117 in Alaska, 56 in Washington, 12 in Oregon, and 71 in California), 225 in Mexico, and 21 in Canada. Full or partial necropsy examinations were conducted on a subset of the whales. Preliminary findings in several of the whales have shown evidence of emaciation. These findings are not consistent across all of the whales examined, so more research is needed. The UME is ongoing, and NMFS continues to investigate the cause(s). Additional information about the UME is available at https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast. Minke Whale The International Whaling Commission (IWC) recognizes three stocks of minke whales in the North Pacific: The Sea of Japan/East China Sea, the rest of the western Pacific west of 180° N, and the remainder of the Pacific (Donovan 1991). Minke whales are relatively common in the Bering and Chukchi seas and in the Gulf of Alaska, but are not considered abundant in any other part of the eastern Pacific (Brueggeman et al., 1990). In the far north, minke whales are thought to be migratory, but they are believed to be year-round residents in coastal waters off the west coast of the United States (Dorsey et al., 1990). Minke whales are reported in Washington inland waters year-round, although few are reported in the winter ( i.e., during the anticipated in-water work window for these projects; Calambokidis and Baird 1994). They are relatively common in the San Juan Islands and Strait of Juan de Fuca (especially around several of the banks in both the central and eastern Strait), but are relatively rare in Puget Sound and the Orca Network has no sighting records of minke whales in the project areas. During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a single minke whale was observed. Long-Beaked Common Dolphin Long-beaked common dolphins are commonly found along the U.S. West Coast, from Baja California, Mexico (including the Gulf of California), northward to about central California (Carretta et al., 2020). The Salish Sea is not considered part of their typical range (Carretta et al., 2020), but there have been reports of long-beaked common dolphins in inland waters. Two individual common dolphins were observed in August and September of 2011 (Whale Museum, 2015). The first record of a pod of long-beaked common dolphins in this area came in the summer of 2016. Beginning on June 16, 2016 long-beaked common dolphins were observed near Victoria, B.C. Over the following weeks, a pod of 15 to 20 (including a calf) was observed in central and southern Puget Sound. They were positively identified as long-beaked common dolphins (Orca Network 2016). Two long-beaked common dolphins were observed by Washington State Department of Transportation (WSDOT) marine mammal monitors during construction at Washington State Ferries Multimodal Project at Colman Dock in Seattle during the 2017-18 construction window (WSDOT 2019). Bottlenose Dolphin Bottlenose dolphins are distributed worldwide from approximately 45° N to 45° S. Bottlenose dolphins inhabiting west coast U.S. waters are considered to be in either the California coastal stock, which ranges from Mexico to the San Francisco area within approximately 1 kilometer of shore, or the California/Oregon/Washington offshore stock, which is most commonly found along the California coast, northward to about the Oregon border. NMFS offshore surveys from 1991 to 2014 resulted in no sightings during study transects off the Oregon or Washington coasts (Carretta et al., 2019). In September 2017, however, multiple sightings of a bottlenose dolphin throughout the Puget Sound and in Elliott Bay were reported to Cascadia Research Collective and Orca Network. One of the individuals was identified as belonging to the California coastal stock (Cascadia Research Collective, 2017). Bottlenose dolphins are considered rare in Puget Sound but occasional sightings have continued since the initial reports in 2017 (Orca Network, 2021). During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a total of 6 bottlenose dolphins were observed, with a maximum of 2 individuals observed on a single day. Pacific White-Sided Dolphin The Pacific white-sided dolphin is found in cool temperate waters of the North Pacific from the southern Gulf of California to Alaska. Across the North Pacific, it appears to have a relatively narrow distribution between 38° N and 47° N (Brownell et al., 1999). In the eastern North Pacific Ocean, the Pacific white-sided dolphin is one of the most common cetacean species, occurring primarily in shelf and slope waters (Green et al., 1993; Barlow 2003, 2010). It is known to occur close to shore in certain regions, including (seasonally) southern California (Brownell et al., 1999). Results of aerial and shipboard surveys strongly suggest seasonal north-south movements of the species between California and Oregon/Washington; the movements apparently are related to oceanographic influences, particularly water temperature (Green et al., 1993; Forney and Barlow 1998; Buchanan et al., 2001). During winter, this species is most abundant in California slope and offshore areas; as northern waters begin to warm in the spring, it appears to move north to slope and offshore waters off Oregon/Washington (Green et al., 1992, 1993; Forney 1994; Forney et al., 1995; Buchanan et al., 2001; Barlow 2003). The highest encounter rates off Oregon and Washington have been reported during March-May in slope and offshore waters (Green et al., 1992). Large groups of Pacific white-sided dolphins have been observed in San Juan Channel (Orca Network 2012), north of Puget Sound, and may rarely occur in Central Puget Sound. During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a total of 2 Pacific white-sided dolphins were observed on one day of construction. Killer Whale There are three distinct ecotypes, or forms, of killer whales recognized in the north Pacific: resident, transient, and offshore. The three ecotypes differ morphologically, ecologically, behaviorally, and genetically. Resident killer whales exclusively prey upon fish, with a clear preference for salmon (Ford and Ellis 2006; Hanson et al., 2010; Ford et al., 2016), while transient killer whales exclusively prey upon marine mammals (Caretta et al., 2019). Less is known about offshore killer whales, but they are believed to consume primarily fish, including several species of shark (Dahlheim et al., 2008). Currently, there are eight killer whale stocks recognized in the U.S. Pacific (Carretta et al., 2021; Muto et al., 2021). Of those, individuals from the West Coast Transient stock may occur in the project areas and be taken incidental to WSDOT's proposed activities. Within Puget Sound, transient killer whales primarily hunt pinnipeds and porpoises, though some groups will occasionally target larger whales. The West Coast Transient stock of killer whales occurs from California through southeast Alaska (Muto et al., 2021). The seasonal movements of transients are largely unpredictable, although there is a tendency to investigate harbor seal haulouts off Vancouver Island more frequently during the pupping season in August and September (Baird 1994; Ford 2014). Transient killer whales have been observed in central Puget Sound in all months (Orca Network 2021). During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a total of 47 transient killer whales were observed, with a maximum of 20 individuals observed on a single day. Harbor Porpoise In the eastern North Pacific Ocean, harbor porpoise are found in coastal and inland waters from Point Barrow, along the Alaskan coast, and down the west coast of North America to Point Conception, California (Gaskin 1984). Harbor porpoise are known to occur year-round in the inland trans-boundary waters of Washington and British Columbia, Canada (Osborne et al., 1988), and along the Oregon/Washington coast (Barlow 1988, Barlow et al., 1988, Green et al., 1992). There was a significant decline in harbor porpoise sightings within southern Puget Sound between the 1940s and 1990s but sightings have increased seasonally in the last 10 years (Carretta et al., 2019). Annual winter aerial surveys conducted by the Washington Department of Fish and Wildlife from 1995 to 2015 revealed an increasing trend in harbor porpoise in Washington inland waters, including the return of harbor porpoise to Puget Sound. The data suggest that harbor porpoise were already present in Juan de Fuca, Georgia Straits, and the San Juan Islands from the mid-1990s to mid-2000s, and then expanded into Puget Sound and Hood Canal from the mid-2000s to 2015, areas they had used historically but abandoned. Changes in fishery-related entanglement was suspected as the cause of their previous decline and more recent recovery, including a return to Puget Sound (Evenson et al., 2016). Seasonal surveys conducted in spring, summer, and fall 2013-2015 in Puget Sound and Hood Canal documented substantial numbers of harbor porpoise in Puget Sound. Observed porpoise numbers were twice as high in spring as in fall or summer, indicating a seasonal shift in distribution of harbor porpoise (Smultea 2015). The reasons for the seasonal shift and for the increase in sightings is unknown. During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a total of 413 harbor porpoises were observed, with a maximum of 40 individuals observed on a single day. Dall's Porpoise Dall's porpoises are endemic to temperate waters of the North Pacific Ocean. Off the U.S. West Coast, they are commonly seen in shelf, slope, and offshore waters (Morejohn 1979). Sighting patterns from aerial and shipboard surveys conducted in California, Oregon, and Washington (Green et al., 1992, 1993; Forney and Barlow 1998; Barlow 2016) suggest that north-south movement between these states occurs as oceanographic conditions change, both on seasonal and inter-annual time scales. Dall's porpoise are considered rare in Puget Sound. During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a total of 8 Dall's porpoises were observed, with a maximum of 5 individuals observed on a single day. California Sea Lion The California sea lion is the most frequently sighted pinniped found in Washington waters and uses haul-out sites along the outer coast, Strait of Juan de Fuca, and in Puget Sound. Haul-out sites are located on jetties, offshore rocks and islands, log booms, marina docks, and navigation buoys. This species also may be frequently seen resting in the water, rafted together in groups in Puget Sound. Only male California sea lions migrate into Pacific Northwest waters, with females remaining in waters near their breeding rookeries off the coast of California and Mexico. The California sea lion was considered rare in Washington waters prior to the 1950s. More recently, peak numbers of 3,000 to 5,000 animals move into the Salish Sea during the fall and remain until late spring, when most return to breeding rookeries in California and Mexico (Jeffries et al., 2000). California sea lions are often observed in the area of potential effects and are known to be comfortable and seemingly curious around human activities. The nearest documented California sea lion haulout is 2.3 mi (3.7 km) southeast of the project sites on Blakely Rocks. Jeffries et al. (2000) estimated less than 100 California sea lions occupy the Blakely Rocks haulout site. California sea lions are not commonly observed in Eagle Harbor but are regularly observed in Elliott Bay, especially around two navigational buoys near Alki Point, at the southwest edge of Elliott Bay. During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a maximum of 38 California sea lions were observed on a single day. Steller Sea Lion Steller sea lions range along the North Pacific Rim from northern Japan to California (Loughlin et al., 1984). There are two separate stocks of Steller sea lions, the Eastern U.S. stock, which occurs east of Cape Suckling, Alaska (144° W), and the Western U.S. stock, which occurs west of that point. Only the Western stock of Steller sea lions, which is designated as the Western DPS of Steller sea lions, is listed as endangered under the ESA (78 FR 66139; November 4, 2013). Unlike the Western U.S. stock of Steller sea lions, there has been a sustained and robust increase in abundance of the Eastern U.S. stock throughout its breeding range. The eastern stock of Steller sea lions has historically bred on rookeries located in Southeast Alaska, British Columbia, Oregon, and California. However, within the last several years a new rookery has become established on the outer Washington coast (at the Carroll Island and Sea Lion Rock complex), with more than 100 pups born there in 2015 (Muto et al., 2020). Steller sea lions use haul-out locations in Puget Sound, and may occur at the same haul-outs as California sea lions, but are considered rare visitors to the waters around Bainbridge Island. Few Steller sea lions have been observed during monitoring of recent construction projects in the Seattle area; typically fewer than 5 total observations per year ( e.g., Anchor QEA 2018, 2019). During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a total of 100 Steller sea lions were observed, with a maximum of 10 Steller sea lions observed on a single day. Harbor Seal Harbor seals inhabit coastal and estuarine waters off Baja California, north along the western coasts of the continental U.S., British Columbia, and Southeast Alaska, west through the Gulf of Alaska and Aleutian Islands, and in the Bering Sea north to Cape Newenham and the Pribilof Islands (Carretta et al., 2014). They haul out on rocks, reefs, beaches, and drifting glacial ice and feed in marine, estuarine, and occasionally fresh waters. Harbor seals generally 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). Within U.S. west coast waters, five stocks of harbor seals are recognized: (1) Southern Puget Sound (south of the Tacoma Narrows Bridge); (2) Washington Northern Inland Waters (including Puget Sound north of the Tacoma Narrows Bridge, the San Juan Islands, and the Strait of Juan de Fuca); (3) Hood Canal; (4) Oregon/Washington Coast; and (5) California. Harbor seals in the project areas would be from the Washington Northern Inland Waters stock. Harbor seals are the only pinniped species that occurs year-round and breeds in Washington waters (Jeffries et al., 2000). Pupping seasons vary by geographic region, with pups born in coastal estuaries (Columbia River, Willapa Bay, and Grays Harbor) from mid-April through June; Olympic Peninsula coast from May through July; San Juan Islands and eastern bays of Puget Sound from June through August; southern Puget Sound from mid-July through September; and Hood Canal from August through January (Jeffries et al., 2000). The most recent estimate for the Washington Northern Inland Waters Stock is 11,036 based on surveys conducted in 1999. There are no current estimates of abundance for this stock but the population is thought to be stable (Carretta et al., 2014). There is one documented harbor seal haulout area near Bainbridge Island at Blakely Rocks, approximately 2.3 mi (3.7 km) southeast of the project sites. The haulout, which is estimated at less than 100 animals, consists of intertidal rocks and reef areas (Jefferies et al., 2000). Harbor seals are a commonly observed marine mammal in the area of potential effects and are known to be comfortable and seemingly curious around human activities. Observations of harbor seals were reported during many recent construction projects along the Seattle waterfront. During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a maximum of 43 harbor seals were observed on a single day. Northern Elephant Seal Northern elephant seals breed and give birth in California (U.S.) and Baja California (Mexico), primarily on offshore islands (Stewart et al., 1994), from December to March (NOAA 2015). Males migrate to the Gulf of Alaska and western Aleutian Islands along the continental shelf to feed on benthic prey, while females migrate to pelagic areas in the Gulf of Alaska and the central North Pacific Ocean to feed on pelagic prey (Le Boeuf et al., 2000). Adults return to land between March and August to molt, with males returning later than females. Adults return to their feeding areas again between their spring/summer molting and their winter breeding seasons (Carretta et al., 2015). During 372 total days of construction at the Washington State Ferries Multimodal Project at Colman Dock in Seattle between 2017 and 2021, a single northern elephant seal was observed. Elephant seals are generally considered rare in Puget Sound. However, a female elephant seal has been reported hauled-out in Mutiny Bay on Whidbey Island periodically since 2010. She was observed alone for her first three visits to the area, but in March 2015, she was seen with a pup. Since then, she has produced two more pups, born in 2018 and 2020. Northern elephant seals generally give birth in January but this individual has repeatedly given birth in March. She typically returns to Mutiny Bay in April and May to molt. Her pups have also repeatedly returned to haul-out on nearby beaches (Orca Network 2020). Marine Mammal Hearing Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007, 2019) recommended that marine mammals be divided into hearing groups based on directly measured (behavioral or auditory evoked potential techniques) or estimated hearing ranges (behavioral response data, anatomical modeling, etc.). Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 decibel (dB) threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall et al. (2007) retained. Marine mammal hearing groups and their associated hearing ranges are provided in Table 4. Table 4—Marine Mammal Hearing Groups (NMFS, 2018) Hearing group Generalized hearing range * Low-frequency (LF) cetaceans (baleen whales) 7 Hz to 35 kHz. Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) 150 Hz to 160 kHz. High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. australis ) 275 Hz to 160 kHz. Phocid pinnipeds (PW) (underwater) (true seals) 50 Hz to 86 kHz. Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) 60 Hz to 39 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 are typically not as broad. Generalized hearing range chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation). The pinniped functional hearing group was modified from Southall et al. (2007) on the basis of data indicating that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids, especially in the higher frequency range (Hemilä et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 2013). For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information. Potential Effects of Specified Activities on Marine Mammals and Their Habitat This section includes a discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The Estimated Take section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The Negligible Impact Analysis and Determination section considers the content of this section, the Estimated Take section, and the Proposed Mitigation section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and whether those impacts are reasonably expected to, or reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival. Acoustic effects on marine mammals during the specified activities can occur from impact pile driving and vibratory driving and removal. The effects of underwater noise from WSDOT's proposed activities have the potential to result in Level A or Level B harassment of marine mammals in the action areas. Description of Sound Sources The marine soundscape is comprised of both ambient and anthropogenic sounds. Ambient sound is defined as the all-encompassing sound in a given place and is usually a composite of sound from many sources both near and far (ANSI 1995). The sound level of an area is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical ( e.g., waves, wind, precipitation, earthquakes, ice, atmospheric sound), biological ( e.g., sounds produced by marine mammals, fish, and invertebrates), and anthropogenic sound ( e.g., vessels, dredging, aircraft, construction). The sum of the various natural and anthropogenic sound sources at any given location and time—which comprise “ambient” or “background” sound—depends not only on the source levels (as determined by current weather conditions and levels of biological and shipping activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 decibels (dB) from day to day (Richardson et al., 1995). The result is that, depending on the source type and its intensity, sound from the specified activities may be a negligible addition to the local environment or could form a distinctive signal that may affect marine mammals. In-water construction activities associated with the projects would include impact and vibratory pile driving and removal. The sounds produced by these activities fall into one of two general sound types: impulsive and non-impulsive. Impulsive sounds ( e.g., explosions, sonic booms, impact pile driving) are typically transient, brief (less than 1 second), broadband, and consist of high peak sound pressure with rapid rise time and rapid decay (ANSI, 1986; NIOSH, 1998; NMFS, 2018). Non-impulsive sounds ( e.g., machinery operations such as drilling or dredging, vibratory pile driving, underwater chainsaws, and active sonar systems) can be broadband, narrowband or tonal, brief or prolonged (continuous or intermittent), and typically do not have the high peak sound pressure with raid rise/decay time that impulsive sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). The distinction between these two 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). Two types of hammers would be used on these projects, impact and vibratory. Impact hammers operate by repeatedly dropping and/or pushing a heavy piston onto a pile to drive the pile into the substrate. Sound generated by impact hammers is considered impulsive. Vibratory hammers install piles by vibrating them and allowing the weight of the hammer to push them into the sediment. Vibratory hammers produce non-impulsive, continuous sounds. Vibratory hammering generally produces SPLs 10 to 20 dB lower than impact pile driving of the same-sized pile (Oestman et al., 2009). Rise time is slower, reducing the probability and severity of injury, and sound energy is distributed over a greater amount of time (Nedwell and Edwards, 2002; Carlson et al., 2005). The likely or possible impacts of WSDOT's proposed activities on marine mammals could be generated from both non-acoustic and acoustic stressors. Potential non-acoustic stressors include the physical presence of the equipment, vessels, and personnel; however, we expect that any animals that approach the project site(s) close enough to be harassed due to the presence of equipment or personnel would be within the Level B harassment zones from pile driving and would already be subject to harassment from the in-water activities. Therefore, any impacts to marine mammals are expected to primarily be acoustic in nature. Acoustic stressors are generated by heavy equipment operation during pile installation and removal ( i.e., impact and vibratory pile driving and removal). Acoustic Impacts The introduction of anthropogenic noise into the aquatic environment from pile driving equipment is the primary means by which marine mammals may be harassed from WSDOT's specified activities. In general, animals exposed to natural or anthropogenic sound may experience physical and psychological effects, ranging in magnitude from none to severe (Southall et al., 2007). Generally, exposure to pile driving and removal and other construction noise has the potential to result in auditory threshold shifts and behavioral reactions ( e.g., avoidance, temporary cessation of foraging and vocalizing, changes in dive behavior). Exposure to anthropogenic noise can also lead to non-observable physiological responses such as an increase in stress hormones. Additional noise in a marine mammal's habitat can mask acoustic cues used by marine mammals to carry out daily functions such as communication and predator and prey detection. The effects of pile driving and demolition noise on marine mammals are dependent on several factors, including, but not limited to, sound type ( e.g., impulsive vs. non-impulsive), the species, age and sex class ( e.g., adult male vs. mother with calf), duration of exposure, the distance between the pile and the animal, received levels, behavior at time of exposure, and previous history with exposure (Wartzok et al., 2004; Southall et al., 2007). Here we discuss physical auditory effects (threshold shifts) followed by behavioral effects and potential impacts on habitat. No physiological effects other than PTS are anticipated or proposed to be authorized, and therefore are not discussed further. NMFS defines a noise-induced threshold shift (TS) as a change, usually an increase, in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS, 2018). The amount of threshold shift is customarily expressed in dB. A TS can be permanent or temporary. As described in NMFS (2018), there are numerous factors to consider when examining the consequence of TS, including, but not limited to, the signal temporal pattern ( e.g., impulsive or non-impulsive), likelihood an individual would be exposed for a long enough duration or to a high enough level to induce a TS, the magnitude of the TS, time to recovery (seconds to minutes or hours to days), the frequency range of the exposure ( i.e., spectral content), the hearing and vocalization frequency range of the exposed species relative to the signal's frequency spectrum ( i.e., how animal uses sound within the frequency band of the signal; e.g., Kastelein et al., 2014), and the overlap between the animal and the source ( e.g., spatial, temporal, and spectral). Permanent Threshold Shift (PTS) —NMFS defines PTS as a permanent, irreversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS 2018). Available data from humans and other terrestrial mammals indicate that a 40 dB threshold shift approximates PTS onset (see Ward et al., 1958, 1959; Ward, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson et al., 2008). PTS levels for marine mammals are estimates, because there are limited empirical data measuring PTS in marine mammals ( e.g., Kastak et al., 2008), largely due to the fact that, for various ethical reasons, experiments involving anthropogenic noise exposure at levels inducing PTS are not typically pursued or authorized (NMFS, 2018). Temporary Threshold Shift (TTS) —TTS is a temporary, reversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS, 2018). Based on data from cetacean TTS measurements (see Southall et al., 2007), a TTS of 6 dB is considered the minimum threshold shift clearly larger than any day-to-day or session-to-session variation in a subject's normal hearing ability (Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in Finneran (2016), marine mammal studies have shown the amount of TTS increases with cumulative sound exposure level (SEL cum ) in an accelerating fashion: At low exposures with lower SEL cum , the amount of TTS is typically small and the growth curves have shallow slopes. At exposures with higher SEL cum , the growth curves become steeper and approach linear relationships with the noise SEL. Depending on the degree (elevation of threshold in dB), duration ( i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious (similar to those discussed in auditory masking, below). For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during time when communication is critical for successful mother/calf interactions could have more serious impacts. We note that reduced hearing sensitivity as a simple function of aging has been observed in marine mammals, as well as humans and other taxa (Southall et al., 2007), so we can infer that strategies exist for coping with this condition to some degree, though likely not without cost. Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin, beluga whale ( Delphinapterus leucas ), harbor porpoise, and Yangtze finless porpoise ( Neophocoena asiaeorientalis )) and five species of pinnipeds exposed to a limited number of sound sources ( i.e., mostly tones and octave-band noise) in laboratory settings (Finneran, 2015). TTS was not observed in trained spotted ( Phoca largha ) and ringed ( Pusa hispida ) seals exposed to impulsive noise at levels matching previous predictions of TTS onset (Reichmuth et al., 2016). In general, harbor seals and harbor porpoises have a lower TTS onset than other measured pinniped or cetacean species (Finneran, 2015). The potential for TTS from impact pile driving exists. After exposure to playbacks of impact pile driving sounds (rate 2,760 strikes/hour) in captivity, mean TTS increased from 0 dB after 15 minute exposure to 5 dB after 360 minute exposure; recovery occurred within 60 minutes (Kastelein et al., 2016). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. No data are available on noise-induced hearing loss for mysticetes. Nonetheless, what we considered is the best available science. For summaries of data on TTS in marine mammals or for further discussion of TTS onset thresholds, please see Southall et al. (2007), Finneran and Jenkins (2012), Finneran (2015), and Table 5 in NMFS (2018). WSDOT proposes to use impact pile driving to install some piles for these projects. There would likely be pauses in activities producing the sound ( e.g., impact pile driving) during each day. Given these pauses and the fact that many marine mammals are likely moving through the project areas and not remaining for extended periods of time, the potential for TS declines. Behavioral Harassment —Exposure to noise from pile driving and removal also has the potential to behaviorally disturb marine mammals. Available studies show wide variation in response to underwater sound; therefore, it is difficult to predict specifically how any given sound in a particular instance might affect marine mammals perceiving the signal. If a marine mammal does react briefly to an underwater sound by changing its behavior or moving a small distance, the impacts of the change are unlikely to be significant to the individual, let alone the stock or population. However, if a sound source displaces marine mammals from an important feeding or breeding area for a prolonged period, impacts on individuals and populations could be significant ( e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 2005). Disturbance may result in changing durations of surfacing and dives, number of blows per surfacing, or moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); or avoidance of areas where sound sources are located. Pinnipeds may increase their haul-out time, possibly to avoid in-water disturbance (Thorson and Reyff, 2006). Behavioral responses to sound are highly variable and context-specific and any reactions depend on numerous intrinsic and extrinsic factors ( e.g., species, state of maturity, experience, current activity, reproductive state, auditory sensitivity, time of day), as well as the interplay between factors ( e.g., Richardson et al., 1995; Wartzok et al., 2004; Southall et al., 2007; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not only among individuals but also within an individual, depending on previous experience with a sound source, context, and numerous other factors (Ellison et al., 2012), and can vary depending on characteristics associated with the sound source ( e.g., whether it is moving or stationary, number of sources, distance from the source). 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. Please see Appendices B and C of Southall et al. (2007) for a review of studies involving marine mammal behavioral responses to sound. Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators ( e.g., bubble nets or sediment plumes), or changes in dive behavior. As for other types of behavioral response, the frequency, duration, and temporal pattern of signal presentation, as well as differences in species sensitivity, are likely contributing factors to differences in response in any given circumstance ( e.g., Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 2007). A determination of whether foraging disruptions incur fitness consequences would require information on or estimates of the energetic requirements of the affected individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal. In 2016, the Alaska Department of Transportation and Public Facilities (ADOT&PF) documented observations of marine mammals during construction activities ( i.e., pile driving) at the Kodiak Ferry Dock (see 80 FR 60636, October 7, 2015). In the marine mammal monitoring report for that project (ABR 2016), 1,281 Steller sea lions were observed within the Level B disturbance zone during pile driving or drilling ( i.e., documented as Level B harassment take). Of these, 19 individuals demonstrated an alert behavior, 7 were fleeing, and 19 swam away from the project site. All other animals (98 percent) were engaged in activities such as milling, foraging, or fighting and did not change their behavior. In addition, two sea lions approached within 20 m of active vibratory pile driving activities. Three harbor seals were observed within the disturbance zone during pile driving activities; none of them displayed disturbance behaviors. Fifteen killer whales and three harbor porpoise were also observed within the Level B harassment zone during pile driving. The killer whales were travelling or milling while all harbor porpoises were travelling. No signs of disturbance were noted for either of these species. Given the similarities in species, activities, and habitat ( e.g., cool-temperate waters, industrialized area), we expect similar behavioral responses from the same and similar species affected by WSDOT's specified activities. That is, disturbance, if any, is likely to be temporary and localized ( e.g., small area movements). Stress responses —An animal's perception of a threat may be sufficient to trigger stress responses consisting of some combination of behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses ( e.g., Seyle 1950; Moberg 2000). In many cases, an animal's first and sometimes most economical (in terms of energetic costs) response is behavioral avoidance of the potential stressor. Autonomic nervous system responses to stress typically involve changes in heart rate, blood pressure, and gastrointestinal activity. These responses have a relatively short duration and may or may not have a significant long-term effect on an animal's fitness. Neuroendocrine stress responses often involve the hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction, altered metabolism, reduced immune competence, and behavioral disturbance ( e.g., Moberg 1987; Blecha 2000). Increases in the circulation of glucocorticoids are also equated with stress (Romano et al., 2004). The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and “distress” is the cost of the response. During a stress response, an animal uses glycogen stores that can be quickly replenished once the stress is alleviated. In such circumstances, the cost of the stress response would not pose serious fitness consequences. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, energy resources must be diverted from other functions. This state of distress will last until the animal replenishes its energetic reserves sufficient to restore normal function. Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses are well-studied through controlled experiments and for both laboratory and free-ranging animals ( e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005). Stress responses due to exposure to anthropogenic sounds or other stressors and their effects on marine mammals have also been reviewed (Fair and Becker 2000; Romano et al., 2002b) and, more rarely, studied in wild populations ( e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. These and other studies lead to a reasonable expectation that some marine mammals will experience physiological stress responses upon exposure to acoustic stressors and that it is possible that some of these would be classified as “distress.” In addition, any animal experiencing TTS would likely also experience stress responses (NRC, 2003), however distress is an unlikely result of these projects based on observations of marine mammals during previous, similar projects in the area. Masking —Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest ( e.g., those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson et al., 1995). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural ( e.g., snapping shrimp, wind, waves, precipitation) or anthropogenic ( e.g., pile driving, shipping, sonar, seismic exploration) in origin. The ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest ( e.g., signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities ( e.g., sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age or TTS hearing loss), and existing ambient noise and propagation conditions. Masking of natural sounds can result when human activities produce high levels of background sound at frequencies important to marine mammals. 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. The Puget Sound area contains active commercial shipping, ferry operations, and commercial fishing as well as numerous recreational and other commercial vessels, and background sound levels in the area are already elevated. Airborne Acoustic Effects —Pinnipeds that occur near the project site could be exposed to airborne sounds associated with pile driving and removal that have the potential to cause behavioral harassment, depending on their distance from pile driving activities. Cetaceans are not expected to be exposed to airborne sounds that would result in harassment as defined under the MMPA. Airborne noise would primarily be an issue for pinnipeds that are swimming or hauled out near the project site within the range of noise levels elevated above the acoustic criteria. We recognize that pinnipeds in the water could be exposed to airborne sound that may result in behavioral harassment when looking with their heads above water. Most likely, airborne sound would cause behavioral responses similar to those discussed above in relation to underwater sound. For instance, anthropogenic sound could cause hauled-out pinnipeds to exhibit changes in their normal behavior, such as reduction in vocalizations, or cause them to temporarily abandon the area and move further from the source. However, these animals would likely previously have been `taken' because of exposure to underwater sound above the behavioral harassment thresholds, which are generally larger than those associated with airborne sound. There are no haulouts near the project sites. Thus, the behavioral harassment of these animals is already accounted for in these estimates of potential take. Therefore, we do not believe that authorization of incidental take resulting from airborne sound for pinnipeds is warranted, and airborne sound is not discussed further here. Marine Mammal Habitat Effects WSDOT's proposed construction activities could have localized, temporary impacts on marine mammal habitat, including prey, by increasing in-water sound pressure levels and slightly decreasing water quality. Increased noise levels may affect acoustic habitat (see masking discussion above) and adversely affect marine mammal prey in the vicinity of the project areas (see discussion below). During impact and vibratory pile driving or removal, elevated levels of underwater noise would ensonify the project areas where both fishes and mammals occur and could affect foraging success. Additionally, marine mammals may avoid the area during construction, however, displacement due to noise is expected to be temporary and is not expected to result in long-term effects to the individuals or populations. Construction activities are of short duration and would likely have temporary impacts on marine mammal habitat through increases in underwater and airborne sound. A temporary and localized increase in turbidity near the seafloor would occur in the immediate area surrounding the area where piles are installed or removed. In general, turbidity associated with pile installation is localized to about a 25-ft (7.6-m) radius around the pile (Everitt et al., 1980). The sediments of the project site will settle out rapidly when disturbed. Cetaceans are not expected to be close enough to the pile driving areas to experience effects of turbidity, and any pinnipeds could avoid localized areas of turbidity. Local currents are anticipated to disburse any additional suspended sediments produced by project activities at moderate to rapid rates depending on tidal stage. Therefore, we expect the impact from increased turbidity levels to be discountable to marine mammals and do not discuss it further. In-Water Construction Effects on Potential Foraging Habitat The area likely impacted by the project is relatively small compared to the available habitat in Puget Sound. The area is highly influenced by anthropogenic activities. The total seafloor area affected by pile installation and removal is a small area compared to the vast foraging area available to marine mammals in the area. At best, the impact area provides marginal foraging habitat for marine mammals and fishes. Furthermore, pile driving and removal at the project site would not obstruct long-term movements or migration of marine mammals. Avoidance by potential prey ( i.e., fish or, in the case of transient killer whales, other marine mammals) of the immediate area due to the temporary loss of this foraging habitat is also possible. The duration of fish and marine mammal avoidance of this area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution, and behavior is anticipated. Any behavioral avoidance by fish or marine mammals of the disturbed area would still leave significantly large areas of fish and marine mammal foraging habitat in the nearby vicinity. In-Water Construction Effects on Potential Prey —Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species ( e.g., crustaceans, cephalopods, fish, zooplankton, other marine mammals). Marine mammal prey varies by species, season, and location. Here, we describe studies regarding the effects of noise on known marine mammal prey other than other marine mammals (which have been discussed earlier). Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning ( e.g., Zelick and Mann, 1999; Fay, 2009). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay et al., 2008). The potential effects of noise on fishes depends on the overlapping frequency range, distance from the sound source, water depth of exposure, and species-specific hearing sensitivity, anatomy, and physiology. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality. Fish react to sounds which are especially strong and/or intermittent low-frequency sounds, and behavioral responses such as flight or avoidance are the most likely effects. Short duration, sharp sounds can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to noise depends on the physiological state of the fish, past exposures, motivation ( e.g., feeding, spawning, migration), and other environmental factors. Hastings and Popper (2005) identified several studies that suggest fish may relocate to avoid certain areas of sound energy. Additional studies have documented effects of pile driving on fish; several are based on studies in support of large, multiyear bridge construction projects ( e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). Several studies have demonstrated that impulse sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs ( e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; Paxton et al., 2017). However, some studies have shown no or slight reaction to impulse sounds ( e.g., Pena et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Popper et al., 2015). SPLs of sufficient strength have been known to cause injury to fish and fish mortality. However, in most fish species, hair cells in the ear continuously regenerate and loss of auditory function likely is restored when damaged cells are replaced with new cells. Halvorsen et al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours for one species. Impacts would be most severe when the individual fish is close to the source and when the duration of exposure is long. Injury caused by barotrauma can range from slight to severe and can cause death, and is most likely for fish with swim bladders. Barotrauma injuries have been documented during controlled exposure to impact pile driving (Halvorsen et al., 2012b; Casper et al., 2013). The most likely impact to fishes from pile driving and removal and construction activities at the project areas would be temporary behavioral avoidance of the area. The duration of fish avoidance of this area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution, and behavior is anticipated. Construction activities, in the form of increased turbidity, have the potential to adversely affect forage fish in the project areas. Forage fish form a significant prey base for many marine mammal species that occur in the project areas. Increased turbidity is expected to occur in the immediate vicinity (on the order of 10 ft (3 m) or less) of construction activities. However, suspended sediments and particulates are expected to dissipate quickly within a single tidal cycle. Given the limited area affected and high tidal dilution rates any effects on forage fish are expected to be minor or negligible. Finally, exposure to turbid waters from construction activities is not expected to be different from the current exposure; fish and marine mammals in Eagle Harbor are routinely exposed to substantial levels of suspended sediment from natural and anthropogenic sources. In summary, given the short daily duration of sound associated with individual pile driving events and the relatively small areas being affected, pile driving activities associated with the proposed actions are not likely to have a permanent, adverse effect on any fish habitat, or populations of fish species. Any behavioral avoidance by fish of the disturbed area would still leave significantly large areas of fish and marine mammal foraging habitat in the nearby vicinity. Thus, we conclude that impacts of the specified activities are not likely to have more than short-term adverse effects on any prey habitat or populations of prey species. Further, any impacts to marine mammal habitat are not expected to result in significant or long-term consequences for individual marine mammals, or to contribute to adverse impacts on their populations. Estimated Take This section provides an estimate of the number of incidental takes proposed for authorization through this IHA, which will inform both NMFS' consideration of “small numbers” and the negligible impact determinations. Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of 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). Authorized takes would primarily be by Level B harassment (in the form of behavioral disturbance and TTS), as use of the acoustic sources ( i.e., vibratory or impact pile driving and removal) have the potential to result in disruption of behavioral patterns and cause a temporary loss in hearing sensitivity for individual marine mammals. There is also some potential for auditory injury (Level A harassment) to result for porpoises and harbor seals because predicted auditory injury zones are larger. The proposed mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable. As described previously, no serious injury or mortality is anticipated or proposed to be authorized for this activity. Below we describe how the proposed take numbers are estimated. For acoustic impacts, generally speaking, we estimate take by considering: (1) Acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (2) the area or volume of water that will be ensonified above these levels in a day; (3) the density or occurrence of marine mammals within these ensonified areas; and, (4) the number of days of activities. We note that while these factors can contribute to a basic calculation to provide an initial prediction of potential takes, additional information that can qualitatively inform take estimates is also sometimes available ( e.g., previous monitoring results or average group size). Below, we describe the factors considered here in more detail and present the proposed take estimates. Acoustic Thresholds NMFS recommends the use of acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur PTS of some degree (equated to Level A harassment). Level B Harassment —Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source or exposure context ( e.g., frequency, predictability, duty cycle, duration of the exposure, signal-to-noise ratio, distance to the source), the environment ( e.g., bathymetry, other noises in the area, predators in the area), and the receiving animals (hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict ( e.g., Southall et al., 2007, 2021, Ellison et al., 2012). Based on what the available science indicates and the practical need to use a threshold based on a metric that is both predictable and measurable for most activities, NMFS typically uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS generally predicts that marine mammals are likely to be behaviorally harassed in a manner considered to be Level B harassment when exposed to underwater anthropogenic noise above root-mean-squared pressure received levels (rms SPL) of 120 dB (referenced to 1 micropascal (re 1 μPa)) for continuous ( e.g., vibratory pile-driving, drilling) and above rms SPL 160 dB re 1 μPa for non-explosive impulsive ( e.g., seismic airguns) or intermittent ( e.g., scientific sonar) sources. WSDOT's proposed activities includes the use of continuous (vibratory hammer) and impulsive (impact hammer) sources, and therefore the 120 and 160 dB re 1 μPa (rms) thresholds are applicable. Level A harassment —NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual criteria to assess auditory injury (Level A harassment) to five different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). WSDOT's activities include the use of impulsive (impact hammer) and non-impulsive (vibratory hammer) sources. These thresholds are provided in the table below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS' 2018 Technical Guidance, which may be accessed at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance. Table 5—Thresholds Identifying the Onset of Permanent Threshold Shift Hearing group PTS onset acoustic thresholds * (received level) Impulsive Non-impulsive Low-Frequency (LF) Cetaceans Cell 1: L pk,flat : 219 dB; L E,LF,24h : 183 dB Cell 2: L E,LF,24h : 199 dB. Mid-Frequency (MF) Cetaceans Cell 3: L pk,flat : 230 dB; L E,MF,24h : 185 dB Cell 4: L E,MF,24h : 198 dB. High-Frequency (HF) Cetaceans Cell 5: L pk,flat : 202 dB; L E,HF,24h : 155 dB Cell 6: L E,HF,24h : 173 dB. Phocid Pinnipeds (PW) (Underwater) Cell 7: L pk,flat : 218 dB; L E,PW,24h : 185 dB Cell 8: L E,PW,24h : 201 dB. Otariid Pinnipeds (OW) (Underwater) Cell 9: L pk,flat : 232 dB; L E,OW,24h : 203 dB Cell 10: L E,OW,24h : 219 dB. * Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be considered. Note: Peak sound pressure ( L pk ) has a reference value of 1 µPa, and cumulative sound exposure level ( L E ) has a reference value of 1µPa 2 s. In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI, 2013). However, ANSI defines peak sound pressure as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript “flat” is being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The 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 acoustic thresholds will be exceeded. Ensonified Area Here, we describe operational and environmental parameters of the activity that are used in estimating the area ensonified above the acoustic thresholds, including source levels and transmission loss coefficient. The sound field in the project areas is the existing background noise plus additional construction noise from the proposed project. Marine mammals are expected to be affected by sound generated by the primary components of the project ( i.e., impact and vibratory pile driving). In order to calculate distances to the Level A harassment and Level B harassment thresholds for the methods and piles being used in these projects, NMFS used acoustic monitoring data from previous pile driving at the Bainbridge Island Ferry Terminal (impact installation of 24-in steel piles) and Eagle Harbor Maintenance Facility (impact installation of 30-in steel piles), as well as pile driving at other locations within Puget Sound to develop source levels for the various pile types, sizes, and methods for the two projects (Table 6). A source level for vibratory driving of 18-in steel piles is not available so it is conservatively assumed to be equivalent to the source level for 24-in steel piles. Table 6—Expected Project Sound Source Levels Pile type and size (in) Method Source level (dB re 1 μPa) Source level measurement distance (m) Reference 12-in timber Vibratory removal 152 dB rms 10 Greenbusch Group (2018). 18-in and 24-in steel Vibratory installation and removal 166 dB rms 10 WSDOT (2020) 1 . 30-in steel Vibratory installation and removal 176 dB rms 6 WSDOT (2020) 1 . 36-in steel Vibratory installation 184 dB rms 10 WSDOT (2020) 1 . 24-in steel Impact installation 206 dB peak; 179 dB SEL; 195 dB rms 10 WSDOT (2020) 1 . 30-in steel Impact installation 194 dB peak; 182 dB SEL; 184 dB rms 10 WSDOT (2020) 1 . 36-in steel Impact installation 205 dB peak; 178 dB SEL; 191 dB rms 10 WSDOT (2020) 1 . 1 WSDOT Biological Assessment Manual Table 7-15. Level B Harassment Zones Transmission loss (TL) is the decrease in acoustic intensity as an acoustic pressure wave propagates out from a source. TL parameters vary with frequency, temperature, sea conditions, current, source and receiver depth, water depth, water chemistry, and bottom composition and topography. The general formula for underwater TL is: TL = B * Log10 (R1/R2) Where: TL = transmission loss in dB B = transmission loss coefficient; for practical spreading equals 15 R1 = the distance of the modeled SPL from the driven pile, and R2 = the distance from the driven pile of the initial measurement The recommended TL coefficient for most nearshore environments is the practical spreading value of 15. This value results in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions, which is the most appropriate assumption for WSDOT's proposed activities in the absence of specific modelling. The Level B harassment zones for WSDOT's proposed activities are shown in Table 7. Level A Harassment Zones The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes. We note that because of some of the assumptions included in the methods underlying this optional tool, we anticipate that the resulting isopleth estimates are typically going to be overestimates of some degree, which may result in an overestimate of potential take by Level A harassment. However, this optional tool offers the best way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources such as pile installation and removal, the optional User Spreadsheet tool predicts the distance at which, if a marine mammal remained at that distance for the duration of the activity, it would be expected to incur PTS. The isopleths generated by the User Spreadsheet used the same TL coefficient as the Level B harassment zone calculations ( i.e., the practical spreading value of 15). Inputs used in the User Spreadsheet ( e.g., number of piles per day, duration and/or strikes per pile) are presented in Tables 1 and 2, and the resulting isopleths are reported below in Table 7. Table 7—Level A Harassment and Level B Harassment Zones Pile size/type Pile driving method Level A harassment zone (m) LF cetaceans MF cetaceans HF cetaceans Phocids Otariids Level B harassment zone (m) 12-in timber Vibratory removal 4.1 0.4 6.1 2.5 0.2 a 1,360 18-in steel Vibratory installation/removal 23.4 2.1 34.5 14.2 1.0 a 11,659 24-in steel Vibratory installation/removal 27.1 2.4 40.1 16.5 1.2 a 11,659 30-in steel Vibratory installation/removal 65.1 5.8 96.2 39.5 2.8 a b 32,470 36-in steel Vibratory installation 485.1 43.0 717.2 294.9 20.7 a b 184,785 24-in steel Impact installation 784.8 27.9 934.8 420.0 30.6 c 2,154 30-in steel Impact installation 1,359.6 48.4 1,619.5 727.6 53.0 c 2,154398 36-in steel Impact installation 795.9 28.3 948.0 425.9 31.0 c 2,1541,166 a Distance to 120 dB rms threshold. b Distance to Level B harassment threshold without obstruction; however for these projects, 13,345 m is the maximum in-water distance until land is reached. c Distance to 160 dB rms threshold. Marine Mammal Occurrence and Take Calculation and Estimation In this section we provide information about the occurrence of marine mammals, including density or other relevant information, that will inform the quantitative estimate of the take that is reasonably likely to occur and proposed for authorization. Unless otherwise specified, the term “pile driving” in this section, and all following sections, may refer to either pile installation or removal. WSDOT first estimated take for both projects using the areas ensonified above the Level B harassment threshold and density estimates for marine mammals in Puget Sound. Density estimates for all species except harbor porpoises were from the U.S. Navy's Marine Species Density Database (MSDD) for the Northwest Training and Testing (NWTT) Study Area (U.S. Navy, 2019). For harbor porpoises, WSDOT used the density estimate from Evenson (2016) as it was considered more conservative than the density estimate for harbor porpoises from the NWTT MSDD. However, for all species except harbor seals and harbor porpoises, WSDOT did not consider the resulting take estimates to be realistic ( i.e., either over- or underestimated take). Instead, WSDOT compiled monitoring results from pile driving between August 2017 and February 2021 at the Seattle Ferry Terminal Multimodal Project at Colman Dock (WSDOT 2021) (Table 8). Because the Level B harassment zones from vibratory pile driving at Colman Dock extended to or near the Bainbridge Island shoreline, and because the Level B harassment zones from vibratory pile driving at the Bainbridge Ferry Terminal and Eagle Harbor Maintenance Facility extend to the shoreline, WSDOT considered the monitoring results from the Seattle Multimodal Project to be the most relevant and comprehensive sightings data available for the project areas. Based on the Seattle Multimodal Project monitoring results, WSDOT used their best professional judgement to estimate the number of marine mammals that may be taken incidental to the proposed activities. NMFS has carefully reviewed WSDOT's analysis and concludes that it represents an appropriate and accurate method for estimating incidental take caused by WSDOT's activities. Table 8—Marine Mammal Density and Sightings Species Density/km 2 Sightings total Average sightings/day (372 days) Maximum one-day sightings Take requested Harbor Seal 3.91 1,939 5.21 43 Yes. Northern Elephant Seal 1 0.0 1 0.003 1 Yes. California Sea Lion 0.0152-0.2211 2,625 7.05 38 Yes. Steller Sea Lion 0.0010-0.0478 100 0.27 10 Yes. Unidentified pinniped N/A 118 N/A 9 N/A. Killer Whale Southern Resident 0.000009-0.007828 297 0.80 26 No. Killer Whale Transient 0.001582-0.002373 47 0.13 20 Yes. Gray Whale 0.000086 4 0.011 1 Yes. Minke Whale 0.00045 1 0.003 1 Yes. Unidentified large whale N/A 2 N/A 1 N/A. Unidentified small whale N/A 10 N/A 9 N/A. Harbor Porpoise 0.58 413 1.11 40 Yes. Dall's Porpoise 0.00045 8 0.02 5 Yes. Pacific White-sided Dolphin 0.0 2 0.005 2 Yes. Long-beaked Common Dolphin 0.0 2 0.005 1 Yes. Common Bottlenose Dolphin 0.0 6 0.02 2 Yes. Unidentified dolphin/porpoise N/A 42 N/A 5 N/A. Gray Whale WSDOT estimated that up to 20 gray whales could be taken by Level B harassment from each project, for a total of 40 takes of gray whales by Level B harassment. In consideration of the infrequent occurrence of gray whales in the project areas, the proposed mitigation and monitoring measures that WSDOT would be required to comply with, including marine mammal monitoring and coordination with Orca Network that would alert WSDOT to the presence of large whales in the project area (see Proposed Mitigation), and given the size and visibility of gray whales, WSDOT would be able to detect gray whales and stop work before gray whales could enter the Level A harassment zones. Therefore, it is unlikely that any gray whales would be taken by Level A harassment. No take of gray whales by Level A harassment is requested or proposed to be authorized. Minke Whale WSDOT estimated that up to 20 minke whales could be taken by Level B harassment from each project, for a total of 40 takes of minke whales by Level B harassment. Like gray whales, in consideration of the infrequent occurrence of minke whales in the project areas, the proposed mitigation and monitoring measures that WSDOT would be required to comply with, including marine mammal monitoring and coordination with Orca Network (see Proposed Mitigation), and given the size and visibility of minke whales, WSDOT would be able to detect minke whales and stop work before minke whales could enter the Level A harassment zones. Therefore, it is unlikely that any minke whales would be taken by Level A harassment. No take of minke whales by Level A harassment is requested or proposed to be authorized. Long-Beaked Common Dolphin WSDOT estimated that up to 20 long-beaked common dolphins could be taken by Level B harassment from each project, for a total of 40 takes of long-beaked common dolphins by Level B harassment. The Level A harassment zones for mid-frequency cetaceans are all less than 50 m. Given the visibility of long-beaked common dolphins, WSDOT would be able to cease pile driving before long-beaked common dolphins could enter the Level A harassment zone. No take of long-beaked common dolphins by Level A harassment is requested or proposed to be authorized. Bottlenose Dolphin WSDOT estimated that up to 20 bottlenose dolphins could be taken by Level B harassment from each project, for a total of 40 takes of bottlenose dolphins by Level B harassment. The Level A harassment zones for mid-frequency cetaceans are all less than 50 m. Given the visibility of bottlenose dolphins, WSDOT would be able to cease pile driving before bottlenose dolphins could enter the Level A harassment zone. No take of bottlenose dolphins by Level A harassment is requested or proposed to be authorized. Pacific White-Sided Dolphin WSDOT estimated that up to 20 Pacific white-sided dolphins could be taken by Level B harassment from each project, for a total of 40 takes of Pacific white-sided dolphins by Level B harassment. The Level A harassment zones for mid-frequency cetaceans are all less than 50 m. Given the visibility of long-beaked common dolphins, WSDOT would be able to cease pile driving before long-beaked common dolphins could enter the Level A harassment zone. No take of long-beaked common dolphins by Level A harassment is requested or proposed to be authorized. Killer Whale (Transient) WSDOT estimated that up to 60 transient killer whales could be taken by Level B harassment from each project, for a total of 120 takes of killer whales by Level B harassment. The Level A harassment zones for mid-frequency cetaceans are all less than 50 m. Given the visibility of killer whales, WSDOT would be able to cease pile driving before killer whales could enter the Level A harassment zone. No take of killer whales by Level A harassment is requested or proposed to be authorized. As stated above, no take of Southern Resident killer whales is expected or proposed to be authorized. Harbor Porpoise To estimate the number of harbor porpoises that may be taken by Level B harassment from the two projects, WSDOT calculated the area ensonified above the Level B harassment threshold for each pile size, type, and method for both projects. WSDOT then multiplied the estimated density of harbor porpoises in the area (0.58 per km 2 ; Evenson 2016) by the ensonified area and the expected days of work for each project element (Table 9). Table 9—Estimated Take of Harbor Porpoises by Level B Harassment Pile size, type, and method Bainbridge ensonified area (km 2 ) Bainbridge days of work Eagle Harbor ensonified area (km 2 ) Eagle Harbor days of work Bainbridge takes by Level B harassment by pile size, type, and method Eagle Harbor takes by Level B harassment by pile size, type, and method 12-in timber vibratory 0.5 5 0.8 13 3 6 18-in steel vibratory N/A 0 23.2 3 0 27 24-in steel vibratory 2.3 2 23.2 3 3 40 30-in steel vibratory 2.3 23 23.2 4 320 53 36-in steel vibratory 2.3 6 23.2 4 84 53 24-in steel impact 0.9 13 0.87 3 17 2 30-in steel impact 0.4 2 N/A 0 3 0 36-in steel impact 0.9 6 0.87 1 8 1 Total 298 183 The areas ensonified above the Level A harassment threshold for high-frequency cetaceans has been omitted from the areas ensonified above the Level B harassment threshold presented in Table 9. For impact installation of 30-in steel piles, the Level A harassment zone for high-frequency cetaceans is approximately 1,620 m. To estimate the number of harbor porpoises that may be present within the Level A harassment zone, WSDOT used the average sightings rate from the Seattle Multimodal Project at Colman Dock (0.691 harbor porpoises per day; Table 8) multiplied by the days of impact pile driving expected for each project (27 days for the Bainbridge Project and 8 days for the Eagle Harbor Project) to estimate that 19 and 6 harbor porpoises may be taken by Level A harassment from the Bainbridge Project and Eagle Harbor Project, respectively, for a total of 25 takes of harbor seals by Level A harassment. Dall's Porpoise WSDOT estimated that up to 20 Dall's porpoises could be taken by Level B harassment from each project, for a total of 40 takes of Dall's porpoises by Level B harassment. For impact installation of 30-in steel piles, the Level A harassment zone for high-frequency cetaceans is approximately 1,620 m. Dall's porpoises are considered rare in the project area and are unlikely to be present within the Level A harassment zones but WSDOT conservatively estimates that no more than 5 Dall's porpoises could enter the Level A harassment zones of each project, for a total of 10 takes of Dall's porpoises by Level A harassment. California Sea Lion Over the course of 372 days of monitoring for the Seattle Multimodal Project at Colman Dock, the average number of California sea lions observed per day was 7.05 (Table 8). WSDOT used that average sightings rate multiplied by the days of work for each project (57 days for the Bainbridge Project and 31 days for the Eagle Harbor Project) to estimate that 402 and 219 California sea lions may be taken by Level B harassment from the Bainbridge Project and Eagle Harbor Project, respectively, for a total of 621 takes of California sea lions by Level B harassment. The largest Level A harassment zone for otariid pinnipeds is 53 m. WSDOT would be required to implement a 60 m shutdown zone for otariids for all pile driving activities. At that close range, WSDOT would be able to detect California sea lions and implement the required shutdown measures before California sea lions could enter the Level A harassment zone. Therefore, no takes of California sea lions by Level A harassment are requested or proposed to be authorized. Steller Sea Lion WSDOT estimated that 180 Steller sea lions could be taken by Level B harassment from each project, for a total of 360 takes of Steller sea lions by Level B harassment. The largest Level A harassment zone for otariid pinnipeds is 53 m. WSDOT would be required to implement a 60 m shutdown zone for otariids for all pile driving activities. At that close range, WSDOT would be able to detect Steller sea lions and implement the required shutdown measures before Steller sea lions could enter the Level A harassment zone. Therefore, no takes of Steller sea lions by Level A harassment are requested or proposed to be authorized. Harbor Seal To estimate the number of harbor seals that may be taken by Level B harassment from the two projects, WSDOT calculated the area ensonified above the Level B harassment threshold for each pile size, type, and method for both projects. WSDOT then multiplied the estimated density of harbor seals in the area (3.91 per km 2 ; Navy 2019) by the ensonified area and the expected days of work for each project element (Table 10). In total, WSDOT estimates that 3,450 harbor seals may be taken by Level B harassment. Table 10—Estimated Take of Harbor Seals by Level B Harassment Pile size, type, and method Bainbridge ensonified area (km 2 ) Bainbridge days of work Eagle Harbor ensonified area (km 2 ) Eagle Harbor days of work Bainbridge takes by pile size, type, and method Eagle Harbor takes by pile size, type, and method 12-in timber vibratory 1.5 5 1.6 13 30 81 18-in steel vibratory N/A 0 24.1 3 0 188 24-in steel vibratory 24.0 2 24.1 3 188 283 30-in steel vibratory 24.0 23 24.1 4 2,158 377 36-in steel vibratory 24.0 6 24.1 4 563 377 24-in steel impact 2.0 13 1.66 3 102 20 30-in steel impact 1.3 2 N/A 0 10 0 36-in steel impact 2.0 6 1.66 1 47 7 Total 2,117 1,333 The areas ensonified above the Level A harassment threshold for high-frequency cetaceans has been omitted from the areas ensonified above the Level B harassment threshold presented in Table 10. For impact installation of 30-in steel piles, the Level A harassment zone for phocid pinnipeds is approximately 728 m. To estimate the number of harbor seals that may be present within the Level A harassment zone, WSDOT used the average sightings rate from the Seattle Multimodal Project at Colman Dock (5.21 harbor seals per day; Table 8) multiplied by the days of impact pile driving expected for each project (27 days for the Bainbridge Project and 8 days for the Eagle Harbor Project) to estimate that 141 and 42 harbor seals may be taken by Level A harassment from the Bainbridge Project and Eagle Harbor Project, respectively, for a total of 183 takes of harbor seals by Level A harassment. Northern Elephant Seal Individual elephant seals have occasionally been reported in central Puget Sound ( e.g., Orca Network, 2020) but are considered rare in the project areas. WSDOT estimated that up to 10 northern elephant seals could be taken by Level B harassment from each project, for a total of 20 takes of northern elephant seals by Level B harassment. The largest Level A harassment zone (728 m) occurs during impact installation of 30-in steel pipe piles (Table 7). It is unlikely that northern elephant seals would be found within this zone, and even more unlikely that northern elephant seals would be found within the Level A harassment zones for vibratory pile driving (up to 295 m). However, even if northern elephant seals were encountered in the project areas, at that close range, WSDOT would be able to detect them and implement the required shutdown measures before any northern elephant seals could enter the Level A harassment zones. Therefore, no take of northern elephant seals by Level A harassment is requested or proposed to be authorized. Table 11—Proposed Take of Marine Mammals by Level A and Level B Harassment From the Bainbridge Project by Species and Stock Species Stock Proposed take by Level B harassment Proposed take by Level A harassment Gray whale Eastern North Pacific 20 0 Minke whale California/Oregon/Washington 20 0 Killer whale West Coast Transient 60 0 Bottlenose dolphin California Coastal 20 0 Long-beaked common dolphin California 20 0 Pacific white-sided dolphin 20 0 Harbor porpoise Washington Inland Waters 298 19 Dall's porpoise California/Oregon/Washington 20 5 California sea lion U.S 402 0 Steller sea lion Eastern 180 0 Northern elephant seal California Breeding 10 0 Harbor seal Washington Northern Inland Waters 2,117 141 Table 12—Proposed Take of Marine Mammals by Level A and Level B Harassment From the Eagle Harbor Project by Species and Stock Species Stock Proposed take by Level B harassment Proposed take by Level A harassment Gray whale Eastern North Pacific 20 0 Minke whale California/Oregon/Washington 20 0 Killer whale West Coast Transient 60 0 Bottlenose dolphin California Coastal 20 0 Long-beaked common dolphin California 20 0 Pacific white-sided dolphin 20 0 Harbor porpoise Washington Inland Waters 183 6 Dall's porpoise California/Oregon/Washington 20 5 California sea lion U.S 219 0 Steller sea lion Eastern 180 0 Northern elephant seal California Breeding 10 0 Harbor seal Washington Northern Inland Waters 1,333 42 Table 13—Total Proposed Take of Marine Mammals by Level A and Level B Harassment, by Species and Stock and Percent of Take by Stock Species Stock Total proposed take by Level A harassment Total proposed take by Level B harassment Total proposed take Percent of stock Gray whale Eastern North Pacific 0 40 40 0.2 Minke whale California/Oregon/Washington 0 40 40 11.0 Killer whale West Coast Transient 0 120 120 34.4 Bottlenose dolphin California Coastal 0 40 40 8.8 Long-beaked common dolphin California 0 40 40 3.2 Pacific white-sided dolphin California/Oregon/Washington 0 40 40 0.2 Harbor porpoise Washington Inland Waters 25 481 506 5.0 Dall's porpoise California/Oregon/Washington 10 40 50 0.3 California sea lion U.S 0 621 621 0.24 Steller sea lion Eastern 0 360 360 0.83 Northern elephant seal California Breeding 0 20 20 0.01 Harbor seal Washington Northern Inland Waters 183 3,450 3,633 32.9 Proposed Mitigation In order to issue an IHA under section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to the activity, and other means of effecting the least practicable impact on the species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stock for taking for certain subsistence uses (latter not applicable for this action). NMFS regulations require applicants for incidental take authorizations to include information about the availability and feasibility (economic and technological) of equipment, methods, and manner of conducting the activity or other means of effecting the least practicable adverse impact upon the affected species or stocks, and their habitat (50 CFR 216.104(a)(11)). In evaluating how mitigation may or may not be appropriate to ensure the least practicable adverse impact on species or stocks and their habitat, as well as subsistence uses where applicable, NMFS considers two primary factors: (1) The manner in which, and the degree to which, the successful implementation of the measure(s) is expected to reduce impacts to marine mammals, marine mammal species or stocks, and their habitat. This considers the nature of the potential adverse impact being mitigated (likelihood, scope, range). It further considers the likelihood that the measure will be effective if implemented (probability of accomplishing the mitigating result if implemented as planned), the likelihood of effective implementation (probability implemented as planned); and (2) The practicability of the measures for applicant implementation, which may consider such things as cost and impact on operations. Shutdown Zones Before the commencement of in-water construction activities, WSDOT would establish shutdown zones for all activities. The purpose of a shutdown zone is generally to define an area within which shutdown of the activity would occur upon sighting of a marine mammal (or in anticipation of an animal entering the defined area). Pile driving would also not commence until all marine mammals are clear of their respective shutdown zones. Shutdown zones are established in consideration of the Level A harassment zones and therefore typically vary based on the activity type and marine mammal hearing group. However, rather than establishing different shutdown zones for each hearing group for each project element, WSDOT proposed to simplify the shutdown zones and implement only 1 or 2 shutdown zones for each hearing group across all project elements (Table 14). For example, the 720 m shutdown zone proposed to be implemented for low-frequency and high-frequency cetaceans for all vibratory pile driving activities encompasses both the largest Level A harassment zone for high-frequency cetaceans (717.2 m; see Table 7) and the largest Level A harassment zone for low-frequency cetaceans (485.1 m; see Table 7). This conservatively protects animals in both hearing groups, simplifies analysis and monitoring, and presents minimal risks to implementing the project, as marine mammals in these hearing groups are unlikely to be present within 720 m of the construction site during pile driving activities. For impact pile driving, WSDOT proposes to retain the 720 m shutdown zone for high-frequency cetaceans but increase the shutdown zone for low-frequency cetaceans to 2,175 m which encompasses the largest Level B harassment zone for impact pile driving, and is also the proposed shutdown zone for preventing take of unauthorized species ( e.g., Southern Resident killer whales, humpback whales) (Table 14). The Level A harassment zones for high-frequency cetaceans from impact pile driving are all greater than 720 m (Table 7), thus any high-frequency cetacean that enters the Level A harassment zone beyond 720 m would be recorded as taken by Level A harassment. At minimum, the shutdown zone for all hearing groups and all activities would be 10 m. For in-water heavy machinery work other than pile driving ( e.g., standard barges, etc. ), if a marine mammal comes within 10 m, operations would cease and vessels would reduce speed to the minimum level required to maintain steerage and safe working conditions. This type of work could include, for example, the movement of the barge to the pile location or positioning of the pile on the substrate via a crane. WSDOT would also establish shutdown zones for all marine mammals for which take has not been authorized or for which incidental take has been authorized but the authorized number of takes has been met. These zones are equivalent to the Level B harassment zones for each activity (see Table 14). WSDOT would also implement shutdown measures for Southern Resident killer whales and humpback whales. If Southern Resident killer whales or humpback whales are sighted within the vicinity of the project areas and are approaching the Level B harassment zone (see Table 14), WSDOT would shut down the pile driving equipment to avoid possible take of these species. If a killer whale approaches the Level B harassment zone during pile driving, and it is unknown whether it is a Southern Resident killer whale or a transient killer whale, it would be assumed to be a Southern Resident killer whale and WSDOT would implement the shutdown measure. If a Southern Resident killer whale, unidentified killer whale, or humpback whale enters the Level B harassment zone undetected, in-water pile driving would be suspended until the whale exits the Level B harassment zone, or 15 minutes have elapsed with no sighting of the animal, to avoid further Level B harassment. Table 14—Shutdown Zones for Pier 58 Reconstruction Pile type and method Shutdown zone (m) LF cetacean MF cetacean HF cetacean Phocids Otariids Southern resident killer whales, humpback whales, and other unauthorized species 12-in timber vibratory 720 60 720 60 60 2,175 18-in steel vibratory 720 60 720 60 60 a 13,345 24-in steel vibratory 720 60 720 60 60 a 13,345 30-in steel vibratory 720 60 720 60 60 a 13,345 36-in steel vibratory 720 60 720 60 60 a 13,345 24-in steel impact 2,175 60 720 60 60 2,175 30-in steel impact 2,175 60 720 60 60 2,175 36-in steel impact 2,175 60 720 60 60 2,175 a 13,345 m is the maximum distance sound can travel before reaching land. Protected Species Observers The placement of protected species observers (PSOs) during all pile driving activities (described in the Proposed Monitoring and Reporting section) would ensure that the entire shutdown zone is visible. Should environmental conditions deteriorate such that the entire shutdown zone would not be visible ( e.g., fog, heavy rain), pile driving would be delayed until the PSO is confident marine mammals within the shutdown zone could be detected. Monitoring for Level A and Level B Harassment PSOs would monitor the Level B harassment zones to the extent practicable, and all of the Level A harassment zones. Monitoring zones provide utility for observing by establishing monitoring protocols for areas adjacent to the shutdown zones. Monitoring zones enable observers to be aware of and communicate the presence of marine mammals in the project areas outside the shutdown zones and thus prepare for a potential cessation of activity should the animal enter the shutdown zone. Pre-Activity Monitoring Prior to the start of daily in-water construction activity, or whenever a break in pile driving of 30 minutes or longer occurs, PSOs would observe the shutdown and monitoring zones for a period of 30 minutes. The shutdown zone would be considered cleared when a marine mammal has not been observed within the zone for that 30-minute period. If a marine mammal is observed within the shutdown zones listed in Table 14, pile driving activity would be delayed or halted. If pile driving is delayed or halted due to the presence of a marine mammal, the activity would not commence or resume until either the animal has voluntarily exited and been visually confirmed beyond the shutdown zones or 15 minutes have passed without re-detection of the animal. When a marine mammal for which Level B harassment take is authorized is present in the Level B harassment zone, activities would begin and Level B harassment take would be recorded. If work ceases for more than 30 minutes, the pre-activity monitoring of the shutdown zones would commence. A determination that the shutdown zone is clear must be made during a period of good visibility ( i.e., the entire shutdown zone and surrounding waters must be visible to the naked eye). Coordination With Local Marine Mammal Research Network Prior to the start of pile driving for the day, the PSOs would contact the Orca Network to find out the location of the nearest marine mammal sightings. The Local Marine Mammal Research Network consists of a list of over 600 (and growing) residents, scientists, and government agency personnel in the United States and Canada. Sightings are called or emailed into the Orca Network and immediately distributed to other sighting networks including: the NMFS Northwest Fisheries Science Center, the Center for Whale Research, Cascadia Research, the Whale Museum Hotline, and the British Columbia Sightings Network. Sightings information collected by the Orca Network includes detection by hydrophone. The SeaSound Remote Sensing Network is a system of interconnected hydrophones installed in the marine environment of Haro Strait (west side of San Juan Island) to study orca communication, in-water noise, bottom fish ecology, and local climatic conditions. A hydrophone at the Port Townsend Marine Science Center measures average in-water sound levels and automatically detects unusual sounds. These passive acoustic devices allow researchers to hear when different marine mammals come into the region. This acoustic network, combined with the volunteer visual sighting network allows researchers to document presence and location of various marine mammal species. Soft Start Soft-start procedures are used to provide additional protection to marine mammals by providing warning and/or giving marine mammals a chance to leave the area prior to the hammer operating at full capacity. For impact pile driving, contractors would be required to provide an initial set of three strikes from the hammer at reduced energy, followed by a 30-second waiting period, then two subsequent reduced- energy strike sets. Soft start would be implemented at the start of each day's impact pile driving and at any time following cessation of impact pile driving for a period of 30 minutes or longer. Bubble Curtain A bubble curtain would be employed during impact installation or proofing of steel piles, unless the piles are driven in the dry, or water is less than 3 ft (0.9 m) in depth. A noise attenuation device would not be required during vibratory pile driving. If a bubble curtain or similar measure is used, it would distribute air bubbles around 100 percent of the piling perimeter for the full depth of the water column. Any other attenuation measure would be required to provide 100 percent coverage in the water column for the full depth of the pile. The lowest bubble ring would be in contact with the mudline for the full circumference of the ring. The weights attached to the bottom ring would ensure 100 percent mudline contact. No [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2022-17141. Public record. Not legal advice.