The proposed action would result in the following increases (above those conducted in previous years, i.e., the No Action Alternative in the Navy's DEIS) in activities:

Overview of the NWTRC

The U.S. Navy has been training and operating in the area now defined as the NWTRC for over 60 years. The NWTRC includes ranges and airspace that extend west to 250 nm (463 km) beyond the coast of Northern California, Oregon, and Washington and east to Idaho. The components of the NWTRC encompass 122,461 nm² (420,163 km²) of surface/subsurface ocean operating areas (OPAREAs), 46,048 nm² (157,928 km²) of special use airspace (SUA), and 875 acres (354 hectares) of land. For range management and scheduling purposes, the NWTRC is divided into numerous subcomponent ranges or training areas used to conduct training and RDT&E of military hardware, personnel, tactics, munitions, explosives, and electronic combat systems, as described in detail in the NWTRC DEIS. As the take of marine mammals is inherently tied to the surface/subsurface OPAREAs of the NWTRC, only those areas are discussed in more detail below.

The LOA application includes graphics (Figures 11, 21, and 22) that depict the sea, undersea, and air spaces used by the Navy. To aid in the description of the range complexes that will be addressed in this proposed rule, the ranges are divided into three major geographic and functional subdivisions. Each of the depicted individual ranges falls into one of these three major range subdivisions:

The Offshore AreaThe Pacific Northwest (PACNW) OPAREA (same footprint as Offshore Area) serves as maneuver water space for ships and submarines to conduct training and to use as transit lanes. It extends from the Strait of Juan de Fuca in the north, to approximately 50 nm (93 km) south of Eureka, California in the south, and from the coast line of Washington, Oregon, and California westward to 130[deg] W. longitude. The PACNW OPAREA is approximately 510 nm (945 km) in length from the northern boundary to the southern boundary, and 250 nm (463 km) from the coastline to the western boundary at 130[deg] W longitude. Total surface area of the PACNW OPAREA is 122,400 nm² (420,163 km²).

Commander Submarine Force, U.S. Pacific Fleet (COMSUBPAC) Pearl Harbor manages this water space as transit lanes for U.S. submarines. While the sea space is ample for all levels of Navy training, no infrastructure is currently in place to support training. There are no dedicated training frequencies, no permanent instrumentation, no meteorological and oceanographic activities (METOC) system, and no Opposition Forces (OPFOR) or Electronic Combat (EC) target systems. In this region of the Pacific Ocean, storms and high sea states can create challenges to surface ship training between October and April. In addition, strong undersea currents in the PACNW make it difficult to place permanent bottommounted instrumentation such as hydrophones.

The Offshore Area undersea space lies beneath the PACNW OPAREA as described above. The bathymetry chart depicts a 100fathom (182m) curve parallel to the coastline approximately 12 nm (22 km) to sea, and in places 20 nm (37 km) out to sea. The area of deeper water of more than 100 fathoms (182 m) is calculated to be approximately 115,800 nm² (397,194 km²), while the shallow water area of less than 100 fathoms (600 ft, 182 m) is all near shore and amounts to approximately 6,600 nm² (22,638 km²).

The Inshore AreaThis area includes all sea and undersea ranges and OPAREAs inland of the coastline, including Puget Sound. This area is composed of approximately 61 nm² of surface and subsurface area. NWTRC Inshore Areas include land ranges, airspace, and two surface/subsurface restricted areasNavy 7 and 3. Activities conducted in each of these areas are not expected to take marine mammals, as defined by the MMPA and therefore, and will not be discussed further in this proposed rule. Also included in the Inshore Area, Explosive Ordnance Disposal (EOD) Ranges are land, sea, and undersea ranges used by NSW and EOD forces specifically for EOD training and are composed of approximately 0.4 nm² of surface and subsurface area within the area identified as the Inshore Area. EOD units located in the NWTRC conduct underwater detonations as part of mine countermeasure training. This training is conducted at one of three locations: Crescent Harbor Underwater EOD Range, offshore from the Seaplane Base at Naval Air Station Whidbey Island; at the Floral Point Underwater EOD Range, located in Hood Canal near NAVBASE Kitsap Bangor; and the Indian Island Underwater EOD Range, adjacent to Indian Island.

Description of Specified Activities

As mentioned above, the Navy has requested MMPA authorization to take marine mammals incidental to training activities in the NWTRC that would result in the generation of sound or pressure waves in the water at or above levels that NMFS has determined will likely result in take (see Acoustic Take Criteria Section), either through the use of MFAS/ HFAS or the detonation of explosives in the water. These activities are discussed in the subsections below. In addition to use of active sonar sources and explosives, these activities include the operation and movement of vessels that are necessary to conduct the training, and the effects of this part of the activities are also analyzed in this document.

The Navy's application also briefly summarizes AntiAir Warfare Training, Naval Special Warfare Training and Support Operations; however, these activities are primarily land and air based and do not utilize sound sources
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or explosives for the portions that are in the water and, therefore, no take of marine mammals is anticipated from these activities and they are not discussed further.

Activities Utilizing Active Sonar Sources

For the NWTRC, the training activities that utilize active tactical sonar sources fall primarily into the category of Antisubmarine Warfare (ASW) exercises (MFAS/HFAS is also used in the mine avoidance exercises, which are considered Mine Warfare Training (MIW) activities; however, it is in such a small amount that impacts to marine mammals are minimal). This section includes a description of ASW, the active acoustic devices used in ASW exercises, and the exercise types in which these acoustic sources are used. Of note, the use of MFAS/HFAS in the NWTRC is minimal as compared to previous rules issued by NMFS (approximately 110 hours annual use of the most powerful surface vessel sonar versus approximately 2,500 hours annual use of AN/SQS53C and AN/ SQS56C sonar in the Southern California Range Complex), does not include major exercises that involve the use of more than one surface vessel MFAS (AN/SQS53C or AN/SQS56C) at a time, and will not occur in the inshore area (i.e., inland from the mouth of the Strait of Juan de Fuca).

ASW Training and Active Sonar

ASW involves helicopter and sea control aircraft, ships, and submarines, operating alone or in combination, to locate, track, and neutralize submarines. Various types of active and passive sonars are used by the Navy to determine water depth, locate mines, and identify, track, and target submarines. Passive sonar ``listens'' for sound waves by using underwater microphones, called hydrophones, which receive, amplify and process underwater sounds. No sound is introduced into the water when using passive sonar. Passive sonar can indicate the presence, character and movement of submarines. However, passive sonar provides only a bearing (direction) to a soundemitting source; it does not provide an accurate range (distance) to the source. Also, passive sonar relies on the underwater target itself to provide sufficient sound to be detected by hydrophones. Active sonar is needed to locate objects that emit little or no noise (such as mines or dieselelectric submarines operating in electric mode) and to establish both bearing and range to the detected contact.

Active sonar transmits pulses of sound that travel through the water, reflect off objects and return to a receiver. By knowing the speed of sound in water and the time taken for the sound wave to travel to the object and back, active sonar systems can quickly calculate direction and distance from the sonar platform to the underwater object. There are three types of active sonar: low frequency, mid frequency, and highfrequency.

LFA sonar is not presently utilized in the NWTRC, and is not part of the Proposed Action.

MFAS, as defined in the Navy's NWTRC LOA application, operates between 1 and 10 kHz, with detection ranges up to 10 nm (19 km). Because of this detection ranging capability, MFAS is the Navy's primary tool for conducting ASW. Many ASW experiments and exercises have demonstrated that this improved capability for long range detection of adversary submarines before they are able to conduct an attack is essential to U.S. ship survivability. Today, ASW is the Navy's number one warfighting priority. Navies across the world utilize modern, quiet, dieselelectric submarines that pose the primary threat to the U.S. Navy's ability to perform a number of critical missions. Extensive training is necessary if Sailors, ships, and strike groups are to gain proficiency in using MFAS. If a strike group does not demonstrate MFAS proficiency, it cannot be certified as combat ready.

HFAS, as defined in the Navy's NWTRC LOA application, operates at frequencies greater than 10 kilohertz (kHz). At higher acoustic frequencies, sound rapidly dissipates in the ocean environment, resulting in short detection ranges, typically less than five nm (9 km). Highfrequency sonar is used primarily for determining water depth, hunting mines and guiding torpedoes.

Acoustic Sources Used for ASW Exercises in the NWTRC

Modern sonar technology has developed a multitude of sonar sensor and processing systems. In concept, the simplest active sonars emit omnidirectional pulses (``pings'') and time the arrival of the reflected echoes from the target object to determine range. More sophisticated active sonar emits an omnidirectional ping and then rapidly scans a steered receiving beam to provide directional, as well as range, information. More advanced active sonars transmit multiple preformed beams, listening to echoes from several directions simultaneously and providing efficient detection of both direction and range. The types of active sonar sources employed during ASW active sonar training exercises in the NWTRC are identified in Table 1. BILLING CODE 351022P
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ASW sonar systems are deployed from certain classes of surface ships, submarines, and fixedwing maritime patrol aircraft (MPA). Maritime patrol aircraft is a category of fixedwing aircraft that includes the current P3C Orion, and the future P8 Poseidon multimission maritime aircraft. No ASW helicopters train in the NWTRC. The
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surface ships used are typically equipped with hullmounted sonars (passive and active) for the detection of submarines. Fixedwing MPA are used to deploy both active and passive sonobuoys to assist in locating and tracking submarines or ASW targets during the exercise. Submarines are equipped with passive sonar sensors used to locate and prosecute other submarines and/or surface ships during the exercise. The platforms used in ASW exercises are identified below.

Surface Ship SonarsA variety of surface ships participate in training events. Of the ships that operate in the NWTRC, only two classes employ MFAS: the Fast Frigate (FFG) and the Guided Missile Destroyer (DDG). These two classes of ship are equipped with active as well as passive tactical sonars for mine avoidance and submarine detection and tracking. DDG class ships are equipped with the AN/SQS 53C sonar system (the most powerful system), with a nominal source level of 235 decibels (dB) re 1 [mu]Pa @ 1 m. The FFG class ship uses the SQS56 sonar system, with a nominal source level of 225 decibels (dB) re 1 [mu]Pa @ 1 m. Sonar ping transmission durations were modeled as lasting 1 second per ping and omnidirectional, which is a conservative assumption that will overestimate potential effects. Actual ping durations will be less than 1 second. The AN/SQS53C hull mounted sonar transmits at a center frequency of 3.5 kHz. The SQS56 transmits at a center frequency of 7.5 kHz. Details concerning the tactical use of specific frequencies and the repetition rate for the sonar pings is classified but was modeled based on the required tactical training setting.

Submarine SonarsSubmarine active sonars are not used for ASW training in the NWTRC. However, the AN/BQS15 sonar would be used for mine detection training. The AN/BQS15, installed on guided missile nuclear submarines (SSGN) and fast attack nuclear submarines (SSN), uses high frequency (> 10 kHz) active sonar to locate mine shapes. A total of seven mine avoidance exercises would take place annually in the NWTRC. Each exercise would last six hours, for a total of 42 hours annually.

Aircraft Sonar SystemsSonobuoys are the only aircraft sonar systems that would operate in the NWTRC. Sonobuoys are deployed by MPAs and are expendable devices used for the detection of submarines. Most sonobuoys are passive, but some can generate active acoustic signals, as well as listen passively. During ASW training, these systems' active modes are used for localization of contacts and are not typically used in primary search capacity. The AN/SSQ62 Directional Command Activated Sonobuoy System (DICASS) is the only MFAS sonobuoy used in the NWTRC. Because no ASW helicopters train in the NWTRC, no dipping sonar system is carried forward for any further analysis of effects.

Extended Echo Ranging and Improved Extended Echo Ranging (EER/IEER) SystemsEER/IEER are airborne ASW systems used to conduct ``large area'' searches for submarines. These systems are made up of airborne avionics ASW acoustic processing and sonobuoy types that are deployed in pairs. The EER/IEER System's active sonobuoy component, the AN/SSQ 110A Sonobuoy, generates an explosive sound impulse and a passive sonobuoy (ADAR, AN/SSQ101A) would ``listen'' for the return echo that has been bounced off the surface of a submarine. These sonobuoys are designed to provide underwater acoustic data necessary for naval aircrews to quickly and accurately detect submerged submarines. The sonobuoy pairs are dropped from a maritime patrol aircraft into the ocean in a predetermined pattern with a few buoys covering a very large area. The AN/SSQ110A Sonobuoy Series is an expendable and commandable sonobuoy. Upon command from the aircraft, the explosive charge would detonate, creating the sound impulse. Within the sonobuoy pattern, only one detonation is commanded at a time. Twelve to twenty SSQ110A source sonobuoys are used in a typical exercise. Both charges of each sonobuoy would be detonated during the course of the training, either tactically to locate the submarine, or when the sonobuoys are commanded to scuttle at the conclusion of the exercise. The AN/SSQ110A is listed in this table because it functions like a sonar ping, however, the source creates an explosive detonation and its effects are considered in the underwater explosive section.

Advanced Extended Echo Ranging (AEER) SystemThe proposed AEER system is operationally similar to the existing EER/IEER system. The AEER system will use the same ADAR sonobuoy (SSQ101A) as the acoustic receiver and will be used for a large area ASW search capability in both shallow and deep water. However, instead of using an explosive AN/ SQS110A as an impulsive source for the active acoustic wave, the AEER system will use a battery powered (electronic) source for the AN/SSQ 125 sonobuoy. The output and operational parameters for the AN/SSQ125 sonobuoy (source levels, frequency, wave forms, etc.) are classified. However, this sonobuoy is intended to replace the EER/IEER's use of explosives and is scheduled to enter the fleet in 2011. Acoustic impact analysis for the AN/SSQ125 in this document assumes a similar perbuoy effect as that modeled for the DICASS sonobuoy. For purposes of analysis, replacement of the EER/IEER system by the AEER system will be assumed to occur at 25% per year as follows: 201125% replacement; 201250% replacement; 201375% replacement; 2014100% replacement with no further use of the EER/IEER system beginning in 2015 and beyond.

TorpedoesTorpedoes are the primary ASW weapon used by surface ships, aircraft, and submarines. The guidance systems of these weapons can be autonomous or electronically controlled from the launching platform through an attached wire. The autonomous guidance systems are acoustically based. They operate either passively, exploiting the emitted sound energy by the target, or actively, ensonifying the target and using the received echoes for guidance. The MK48 submarine launched torpedo, used in its antisurface ship mode, was modeled for active sonar transmissions in Sinking Exercises conducted within the NWTRC.

Portable Undersea Tracking RangeThe Portable Undersea Tracking Range (PUTR) has been developed to support ASW training in areas where the ocean depth is between 300 ft and 12,000 ft and at least 3 nm from land. This proposed project would temporarily instrument 25squaremile or smaller areas on the seafloor, and would provide high fidelity feedback and scoring of crew performance during ASW training activities. When training is complete, the PUTR equipment would be recovered. All of the potential PUTR areas have been used for ASW training for decades.

No onshore construction would take place. Seven electronics packages, each approximately 3 ft long by 2 ft in diameter, would be temporarily installed on the seafloor by a range boat, in water depths greater than 600 ft. The anchors used to keep the electronics packages on the seafloor would be either concrete or sand bags, approximately 1.5 ftby1.5 ft and 300 pounds. Each package consists of a hydrophone that receives pinger signals, and a transducer that sends an acoustic ``uplink'' of locating data to the range boat. The uplink signal is transmitted at 8.8 kilohertz (kHz), 17 kHz, or 40 kHz, at a source level of 190 decibels (dB). The Portable Undersea Tracking Range [[Page 33833]]
system also incorporates an underwater voice capability that transmits at 811 kHz and a source level of 190 dB. Each of these packages is powered by a D cell alkaline battery. After the end of the battery life, the electronic packages would be recovered and the anchors would remain on the seafloor. The Navy proposes to deploy this system for 3 months of the year (approximately JuneAugust), and to conduct TRACKEX activities for 10 days per month in an area beyond 3 nm from shore. During each of the 30 days of annual operation, the PUTR would be in use for 5 hours each day. No additional ASW activity is proposed as a result of PUTR use. Operation of this range requires that underwater participants transmit their locations via pingers and that the receiving transducers transmit that information the range boat via the Uplink transmitter (see ``Range Tracking Pingers'' and uplink transmitter ``below'').

Range Tracking PingersMK84 range tracking pingers would be used on ships, submarines, and ASW targets when ASW TRACKEX training is conducted on the PUTR. The MK84 pinger generates a 12.93 kHz sine wave in pulses with a maximum duty cycle of 30 milliseconds (3% duty cycle) and has a design power of 194 dB re 1 microPascal at 1 meter. Although the specific exercise, and number and type of participants will determine the number of pingers in use at any time, a minimum of one and a maximum of three pingers would be used for each ASW training activity. On average, two pingers would be in use for 3 hours each during PUTR operational days.

Uplink TransmittersEach package consists of a hydrophone that receives pinger signals, and a transducer that sends an acoustic ``uplink'' of locating data to the range boat. The uplink signal is transmitted at 8.8 kilohertz (kHz), 17 kHz, or 40 kHz, at a source level of 190 decibels (dB). The Portable Undersea Tracking Range system also incorporates an underwater voice capability that transmits at 811 kHz and a source level of 190 dB. Under the proposed action, the uplink transmitters would operate 30 days per year, for 5 hours each day of use. The total time of use would be 150 hours annually.

Exercises Utilizing MFAS in the NWTRC

ASW Tracking Exercises are the exercises that primarily utilize MFAS and HFAS sources in the NWTRC, although Mine Avoidance MIW exercises also utilize a less powerful HFAS source. ASW Tracking Exercise (TRACKEX) trains aircraft, ship, and submarine crews in tactics, techniques, and procedures for search, detection, localization, and tracking of submarines with the goal of determining a firing solution that could be used to launch a torpedo and destroy the submarine. ASW Tracking Exercises occur during both day and night. A typical unitlevel exercise involves one (1) ASW unit (aircraft, ship, or submarine) versus one (1) targeteither a MK39 Expendable Mobile ASW Training Target (EMATT), or a live submarine. The target may be nonevading while operating on a specified track or fully evasive. Participating units use active and passive sensors, including hull mounted sonar, towed arrays, and sonobuoys for tracking. If the exercise continues into the firing of a practice torpedo it is termed a Torpedo Exercise (TORPEX). The ASW TORPEX usually starts as a TRACKEX to achieve the firing solution. No torpedoes are fired during ASW training conducted in the NWTRC. The exercise types that utilize MFAS/ HFAS are described below and summarized in Table 2, which also includes a summary of the exercise types utilizing explosives.

ASW TRACKEX (Maritime Patrol Aircraft)During an ASW TRACKEX (MPA), a typical scenario would involve a single MPA dropping sonobuoys, from an altitude below 3,000 ft (914 m) above mean sea level (MSL), and sometimes as low as 400 ft (122 m), into specific patterns designed for both the anticipated threat submarine and the specific water conditions. These patterns vary in size and coverage area based on the threat and water conditions.

Typically, passive sonobuoys will be used first, so the threat submarine is not alerted. Active buoys will be used as required either to locate extremely quiet submarines, or to further localize and track submarines previously detected by passive buoys. A TRACKEX (MPA) usually takes two to four hours. The P8 Multimission Maritime Aircraft (MMA), a modified Boeing 737 that is the Navy's replacement for the aging P3 Orion aircraft, is a longrange aircraft that is capable of broadarea, maritime and littoral activities. As P8 live training is expected to be supplemented with virtual training to a greater degree than P3 training, P8 training activities in the NWTRC are likely to be less numerous than those currently conducted by P3 aircraft crews. P3 replacement is expected to begin by 2013. None of the potential marine mammal impacts associated with the P3 aircraft are expected to differ as a result of the P3 being replaced by the MMA.

ASW TRACKEX (EER/IEER or AEER)This activity is an atsea flying event, typically conducted below 3,000 ft (914 m) MSL, that is designed to train P3 crews in the deployment and use of the EER/IEER (and in the future, AEER) sonobuoy systems. These systems use the SSQ110A as the signal source and the SSQ77 (VLAD) as the receiver buoy. The signal source is a small explosive charge that detonates underwater. The SSQ110A sonobuoy has two charges, each being individually detonated during the exercise. This activity typically lasts six hours, with one hour for buoy pattern deployment and five hours for active search. Between 12 and 20 SSQ110A source sonobuoys and approximately 20 SSQ77 passive sonobuoys are used in a typical exercise.

ASW TRACKEX (Surface Ship)In the PACNW OPAREA, locally based surface ships do not routinely conduct ASW Tracking exercises. However, MFAS is used during ship transits through the OPAREA. In a typical year, 24 DDG ship transits and 36 FFG transits will take place, with 1.5 hours of active sonar use during each transit. All surface ship MFAS use is documented in this training activity description. 10% of surface ship MFAS used in NWTRC is training associated with the PUTR.

ASW TRACKEX (Submarine)ASW TRACKEX is a primary training exercise for locally based submarines. Training is conducted within the NWTRC and involves aircraft approximately 30% of the time. Training events in which aircraft are used typically last 8 to 12 hours. During these activities submarines use passive sonar sensors to search, detect, classify, localize and track the threat submarine with the goal of developing a firing solution that could be used to launch a torpedo and destroy the threat submarine. However, no torpedoes are fired during this training activity. All submarine ASW TRACKEX conducted in the NWTRC is passive only; therefore, these activities are not carried forward for any further analysis of effects. All aircraft ASW is analyzed under ASW TRACKEX (MPA).

Mine AvoidanceMine avoidance exercises train ship and submarine crews to detect and avoid underwater mines. In the NWTRC, submarine crews will use the AN/BQS15 high frequency active sonar to locate mine shapes in a training minefield in the PACNW OPAREA. A smallscale underwater minefield will be added in the NWTRC for these exercises. Each mine avoidance exercise involves one submarine operating the AN/ BQS15 sonar for six hours to navigate through
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the training minefield. A total of seven mine avoidance exercises will occur in the NWTRC annually.
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Activities Utilizing Underwater Detonations

Underwater detonation activities can occur at various depths depending on the activity, but may also include activities which may have detonations at or just below the surface (such as SINKEX or gunnery exercise [GUNEX]). When the weapons hit the target, except for live torpedo shots, there is no explosion in the water, and so a ``hit'' is not modeled (i.e., the energy (either acoustic or pressure) from the hit is not expected to reach levels that would result in take of marine mammals). When a live weapon misses, it is modeled as exploding below the water surface at 1 ft (5inch naval gunfire, 76mm rounds), 2 meters (Maverick, Harpoon, MK82, MK83, MK84), or 50ft (MK48 torpedo) as shown in Appendix A of the Navy's application (the depth is chosen to represent the worst case of the possible scenarios as related to potential marine mammal impacts). Exercises may utilize either live or inert ordnance of the types listed in Table 3. Additionally, successful hit rates are known to the Navy and are utilized in the effects modeling. Training events that involve explosives and underwater detonations occur throughout the year and are described below and summarized in Table 2. Of note, the only Inshore Area exercises that use explosives are on EOD ranges described under Mine Countermeasures (No more than 4 total detonations of 2.5 lb. charges annually).
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AntiSurface Warfare Training (ASUW)

AntiSurface Warfare (ASUW) is the category of activity that addresses combat (or interdiction) activities training by air, surface, or submarine forces against hostile surface ships and boats. The ASUW exercises conducted in NWTRC are described in the sections below. Because all of the rounds used in GUNEX in the NWTRC are inert, no take of marine mammals is anticipated to
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result from the activity. However, a description is included here for comparison and clarity as NMFS has authorized take of marine mammals incidental to these activities in the past when explosive rounds were used instead of inert rounds.

AirtoSurface Bombing ExerciseDuring an AirtoSurface Bombing Exercise (BOMBEX AS), fixedwing aircraft deliver bombs against simulated surface maritime targets, typically a smoke float, with the goal of destroying or disabling enemy ships or boats. MPA use bombs to attack surfaced submarines and surface craft that would not present a major threat to the MPA itself. A single MPA approaches the target at a low altitude. In most training exercises, the aircrew drops inert training ordnance, such as the Bomb Dummy Unit (BDU45) on a MK58 smoke float used as the target. Historically, ordnance has been released throughout W237 (off WA State), just south of W237, and in international waters in accordance with international laws, rules, and regulations. Annually, 120 pieces of ordnance, consisting of 10 MK82 live bombs and 110 BDU 45 inert bombs, are dropped in the NWTRC. In accordance with the regulations for the Olympic Coast National Marine Sanctuary (OCNMS) the Navy dos not conduct live bombing in the sanctuary. Each BOMBEX AS can take up to 4 hours to complete.

Sinking ExerciseA Sinking Exercise (SINKEX) is typically conducted by aircraft, surface ships, and submarines in order to take advantage of a full size ship target and an opportunity to fire live weapons. The target is typically a decommissioned combatant or merchant ship that has been made environmentally safe for sinking. In accordance with EPA permits, it is towed out to sea (at least 50 nm [92.6 km]) and set adrift at the SINKEX location in deep water (at least 1,000 fathoms [6,000 feet]) where it will not be a navigation hazard to other shipping. The Environmental Protection Agency (EPA) granted the Department of the Navy a general permit through the Marine Protection, Research, and Sanctuaries Act to transport vessels ``for the purpose of sinking such vessels in ocean waters * * *'' (40 CFR Part 229.2). Subparagraph (a)(3) of this regulation states ``All such vessel sinkings shall be conducted in water at least 1,000 fathoms (6,000 feet) deep and at least 50 nautical miles from land.''

Ship, aircraft, and submarine crews typically are scheduled to attack the target with coordinated tactics and deliver live ordnance to sink the target. Inert ordnance is often used during the first stages of the event so that the target may be available for a longer time. The duration of a SINKEX is unpredictable because it ends when the target sinks, but the goal is to give all forces involved in the exercise an opportunity to deliver their live ordnance. Sometimes the target will begin to sink immediately after the first weapon impact and sometimes only after multiple impacts by a variety of weapons. Typically, the exercise lasts 4 to 8 hours, especially if inert ordnance such as 5 inch gun projectiles or MK76 dummy bombs are used during the first hours. In the worst case of maximum exposure, the following ordnance are all expended (in the indicated amounts): MK82 Live Bomb (4); MK83 Live Bomb (4); MK84 Live Bomb (4); HARM Missile (2); AGM114 Hellfire Missile (1); M65 Maverick Missile (3); M84 Harpoon Missile (3); AM ER Missile (1); 5 in/62 Shell (500); 76 mm Shell (200); 48 ADCAP Torpedo (1). If the hulk is not sunk by weapons, it will be sunk by Explosive Ordnance Disposal (EOD) personnel setting off demolition charges previously placed on the ship. Since the target may sink at any time during the exercise, the actual number of weapons used can vary widely.

SurfacetoSurface Gunnery ExerciseSurfacetoSurface Gunnery Exercises (SS GUNEX) take place in the open ocean to provide gunnery practice for Navy ship crews. Exercises can involve a variety of surface targets that are either stationary or maneuverable. Gun systems employed against surface targets include the 5, 76 mm, 57 mm, .50 caliber and the 7.62 mm. A GUNEX lasts approximately one to two hours, depending on target services and weather conditions. All rounds fired are inert, containing no explosives.

Mine Warfare Training (MIW)

Mine Warfare Training includes Mine Countermeasures and Mine Avoidance. Mine Avoidance includes use of an active sonar source (although in very small amounts) and, therefore, was addressed in the appropriate section previously. Because of the location of the EOD ranges, the very limited use of explosives (4 individual explosions) proposed annually for these Mine Countermeasure exercises, and the likely effectiveness of the mitigation (e.g., marine mammal take is only expected within 180 m of the impact area, which is well within the shutdown zone of 700 yds from the point of impact), take of marine mammals is not anticipated to occur in the NWTRC. However, a description is included here for comparison as NMFS has authorized take of marine mammals incidental to these activities in other areas where the amount of activity is significantly greater.

Mine CountermeasuresNaval EOD personnel require proficiency in underwater mine neutralization. Mine neutralization activities consist of underwater demolitions designed to train personnel in the destruction of mines, unexploded ordnance (UXO), obstacles, or other structures in an area to prevent interference with friendly or neutral forces and noncombatants. EOD units conduct underwater demolition training in Crescent Harbor Underwater EOD Range, Indian Island Underwater EOD Range, and Floral Point Underwater EOD Range. A 2.5 lb (1.1 kg) charge of C4 is used, consisting of one surface or one subsurface detonation. No more than two detonations will take place annually at Crescent Harbor, and no more than one each at Indian Island and Floral Point. The total duration of the exercise is four hours for an underwater detonation and one hour for a surface detonation. Small boats such as the MK5 Combat Rubber Raiding Craft and MK7, or 9 (meters in length, respectively) Rigid Hull Inflatable Boats (RHIB) are used to insert personnel for underwater activities and either a helicopter (H60) or RHIB is used for insertion for surface activities. Vessel Movement

The operation and movement of vessels that is necessary to conduct the training described above is also analyzed here. Training exercises involving vessel movements occur intermittently and are variable in duration, ranging from a few hours up to 2 weeks. During training, speeds vary and depend on the specific type of activity, although 1014 knots is considered the typical speed. Approximately 490 training activities that involve Navy vessels occur within the Study Area during a typical year. Training activities are widely dispersed throughout the large OPAREA, which encompasses 122,468 nm\2\ (420,054 km\2\). Consequently, the density of Navy ships within the Study Area at any given time is low.

Research, Development, Testing, and Evaluation

RDT&E proposed in this action is limited to Unmanned Aerial Systems (UAS) activities, the use of which is not anticipated to result in the take of marine mammals because it utilizes small, relatively quiet airborne, not undersea, gliders. Undersea RDT&E in the Pacific Northwest is conducted at
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the Naval Sea Systems Command (NAVSEA) Keyport range and is analyzed in the NAVSEA Naval Undersea Warfare Center (NUWC) Keyport Range Extension EIS/OEIS.

Additional information on the Navy's proposed activities may be found in the LOA Application and the Navy's NWTRC DEIS.
Description of Marine Mammals in the Area of the Specified Activities

The California Current passes through the NWTRC, creating a mixing of temperate and tropical waters, thereby making this area one of the most productive ocean systems in the world (Department of the Navy [DoN], 2002a). Because of this productive environment, there is a rich marine mammal fauna, as evidenced in abundance and species diversity (Leatherwood et al., 1988; Bonnell and Dailey, 1993). In addition to many marine mammal species that live here yearround and use the region's coasts and islands for breeding and hauling out, there is a community of seasonal residents and migrants. The narrow continental shelf along the Pacific coast and the presence of the cold California Current sweeping down from Alaska allows coldwater marine mammal species to reach nearshore waters as far south as Baja California.

Thirtythree marine mammal species or populations/stocks have confirmed or possible occurrence within the NWTRC, including six species of baleen whales (mysticetes), 21 species of toothed whales (odontocetes), five species of seals and sea lions (pinnipeds), and the sea otter (mustelids). Table 4 summarizes their abundance, Endangered Species Act (ESA) status, population trends, and occurrence in the area. Most of these species are listed as ``common'' in the table, indicating that they occur routinely, either yearround or during annual migrations into or through the area. The other species are indicated as ``rare'' because of sporadic sightings or as ``very rare'' because they have been documented once or twice as appearing outside their normal range. All of the species that occur in the NWTRC are either cosmopolitan (occur worldwide), or associated with the temperate and subArctic oceans (Leatherwood et al., 1988). Seven of the species are ESAlisted and considered depleted under the MMPA: Blue whale; fin whale; humpback whale; sei whale; sperm whale; southern resident killer whale; and Steller sea lion.

Temperate and warmwater toothed whales often change their distribution and abundance as oceanographic conditions vary both seasonally (Forney and Barlow, 1998) and interannually (Forney, 2000). Forney and Barlow (1998) noted significant north/south shifts in distribution for Dall's porpoises, common dolphins, and Pacific white sided dolphins, and they identified significant inshore/offshore differences for northern right whale dolphins and humpback whales. Several authors have noted the impact of the El Ni[ntilde]o events of 1982/1983 and 1997/1998 on marine mammal occurrence patterns and population dynamics in the waters off California (Wells et al., 1990; Forney and Barlow, 1998; Benson et al., 2002).

The distribution of some marine mammal species is based on the presence of salmon, an important prey source. Seals and sea lions congregate near areas where migrating salmon run. For example, in the San Juan Islands, harbor seals (Phoca vitulina richardii) congregate near a constricted channel where incoming tidal currents funnel migrating salmon (Zamon, 2001). In Oregon, harbor seals wait for chum salmon runs during the incoming tide near a constriction in Netarts Bay (Brown and Mat, 1983). During the summer, southern resident killer whales (Orcinus orca) congregate at locations associated with high densities of migrating salmon (HeimlichBoran, 1986; Nichol and Shackleton, 1996; Olson, 1998; National Marine Fisheries Service [NMFS], 2005i). Their strong preference for Chinook salmon may influence the yearround distribution patterns of southern resident killer whales in the NWTRC (Ford and Ellis, 2005).

The Navy has compiled information on the abundance, behavior, status and distribution, and vocalizations of marine mammal species in the NWTRC waters from the Navy Marine Resource Assessment for NWTRC (which was recently updated, during the development of the application for this rule, based on peerreviewed literature and government reports such as NMFS' Stock Assessment Reports) and marine mammal experts engaged in current research utilizing tagging and tracking. This information may be viewed in the Navy's LOA application and/or the Navy's DEIS for NWTRC (see Availability), and is incorporated by reference herein. Included below, however, are summaries of some important biological issues that are needed to further inform the MMPA effects analysis. Additional information is available in NMFS Stock Assessment Reports, which may be viewed at: http://www.nmfs.noaa.gov/ pr/sars/species.htm.
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Species Not Considered Further

The North Pacific right whale is classified as endangered under the ESA. Although there is designated critical habitat for this species in the western Gulf of Alaska and an area in the southeastern Bering Sea (NMFS, 2006), there is no designated critical habitat for this species within the NWTRC. Census data are too limited to suggest a population trend for this species. In the western North Pacific, the population may number in the low hundreds (Brownell et al., 2001; Clapham et al., 2004). The eastern population likely now numbers in the tens of animals. Right whales were probably never common along the west coast of North America (Scarff, 1986; Brownell et al., 2001). Historical whaling records provide the most complete information on likely North Pacific right whale
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distribution. Presently, sightings are extremely rare, occurring primarily in the Okhotsk Sea and the eastern Bering Sea (Brownell et al., 2001; Shelden et al., 2005; Shelden and Clapham, 2006; Wade et al., 2006). There were no sightings of North Pacific right whales during ship surveys conducted off California, Oregon, and Washington from 1991 through 2005 (Barlow and Forney, 2007), although recent deployment of directional sonobuoys (focused on the gunshot call) in the southeastern Bering Sea has resulted in multiple recordings of the rarely detected marine mammals (Berchok et al., 2009). The area of densest concentration in the Gulf of Alaska is east from 170[deg] W to 150[deg] W and south to 52[deg] N (Shelden and Clapham, 2006). Based upon the extremely low probability of encountering this species anywhere in the coastal and offshore waters in the NWTRC, this species will not be included in this analysis.
Designated Critical Habitat

Southern Resident Killer Whale

NMFS designated critical habitat for the southern resident killer whale (Orcinus orca) distinct population segment (DPS). Three specific areas (which comprise approximately 2,560 square miles (6,630 sq km) of marine habitat) are designated:
(1) The Summer Core Area in Haro Strait and waters around the San Juan IslandsOccurrence of Southern Residents in Area 1 coincides with concentrations of salmon, and is more consistent and concentrated in the summer months of June through August, though they have been sighted in Area 1 during every month of the year;
(2) Puget Soundsouthern resident killer whale occurrence in Area 2 has been correlated with fall salmon runs; and
(3) The Strait of Juan de FucaAll pods regularly use the Strait of Juan de Fuca for passage from Areas 1 and 2 to outside waters in the Pacific Ocean and to access outer coastal water feeding grounds.

The designated physical and biological features which are essential to the conservation of southern resident killer whales and that may require special management considerations or protection (Primary Constituent Elements/PCEs) are as follows:
(1) Water quality to support growth and developmentBecause of their long life span, position at the top of the food chain, and their blubber stores, southern resident killer whales accumulate high concentrations of contaminants;
(2) Prey species of sufficient quantity, quality and availability to support individual growth, reproduction and development, as well as overall population growthFish are the major dietary component of southern resident killer whales in the northeastern Pacific. Salmon comprise the southern resident killer whales' preferred prey, and are likely consumed in large amounts; and
(3) Passage conditions to allow for migration, resting, and foragingIn order to move between important habitat areas, find prey, and fulfill other life history requirements, southern resident killer whales require open waterways that are free from obstruction.

As noted previously, the Navy's proposed action does not include the use of MFAS/HFAS in southern resident killer whale critical habitat, and explosive use is limited to four detonations of 2.5lb charges annually in EOD exercises.

Steller Sea Lion

In California and Oregon, major Steller sea lion rookeries and associated air and aquatic zones are designated as critical habitat. Critical habitat includes an air zone extending 3,000 ft above rookery areas historically occupied by sea lions and an aquatic zone extending 3,000 seaward. Three rookeries located along the southern Oregon Coast have been designated as critical habitat sites in the NWTRC. These include: Orford Reef (Long Brown Rock); Oxrord Reef (Seal Rock); Rogue Reef (Pyramid Rock). The PCEs for Steller sea lions are: Nearshore waters around rookeries and haulouts and prey resources and foraging habitats.

Gray Whale Migration

The gray whale makes a welldefined seasonal northsouth migration. Most of the population summers in the shallow waters of the northern Bering Sea, the Chukchi Sea, and the western Beaufort Sea (Rice and Wolman, 1971), whereas some individuals also summer along the Pacific coast from Vancouver Island to central California (Rice and Wolman, 1971; Darling 1984; Nerini, 1984). In October and November, the whales begin to migrate southeast through Unimak Pass and follow the shoreline south to breeding grounds on the west coast of Baja California and the southeastern Gulf of California (Braham, 1984; Rugh, 1984). The average gray whale migrates 7,50010,000 km at a rate of 147 km/d (Rugh et al., 2001; Jones and Swartz, 2002). Although some calves are born along the coast of California, most are born in the shallow, protected waters on the Pacific coast of Baja California from Morro de Santo Domingo (28[deg] N) south to Isla Creciente (24[deg] N) (Urban et al., 2003). The main calving sites are Laguna Guerrero Negro, Laguna Ojo de Liebre, Laguna San Ignacio, and Estero Soledad (Rice et al., 1981).

Gray whales occur in the Pacific Northwest OPAREA and Puget Sound throughout the year. In addition, larger numbers of migratory animals transit along the coast of Washington, Oregon, and California during migrations between breeding and feeding grounds. Peak sightings in the NWTRC during the southbound migration occur in January (Rugh et al., 2001). There are two phases of the northbound migration, including an early phase from midFebruary through April and a later phase, which consists of mostly cows and calves, from late April through May (Herzing and Mate, 1984).

Marine Mammal Hearing and Vocalizations

Cetaceans have an auditory anatomy that follows the basic mammalian pattern, with some changes to adapt to the demands of hearing in the sea. The typical mammalian ear is divided into an outer ear, middle ear, and inner ear. The outer ear is separated from the inner ear by a tympanic membrane, or eardrum. In terrestrial mammals, the outer ear, eardrum, and middle ear transmit airborne sound to the inner ear, where the sound waves are propagated through the cochlear fluid. Since the impedance of water is close to that of the tissues of a cetacean, the outer ear is not required to transduce sound energy as it does when sound waves travel from air to fluid (inner ear). Sound waves traveling through the inner ear cause the basilar membrane to vibrate. Specialized cells, called hair cells, respond to the vibration and produce nerve pulses that are transmitted to the central nervous system. Acoustic energy causes the basilar membrane in the cochlea to vibrate. Sensory cells at different positions along the basilar membrane are excited by different frequencies of sound (Pickles, 1998). Baleen whales have inner ears that appear to be specialized for low frequency hearing. Conversely, dolphins and porpoises have ears that are specialized to hear high frequencies.

Marine mammal vocalizations often extend both above and below the range of human hearing; vocalizations with frequencies lower than 18 Hertz (Hz) are labeled as infrasonic and those higher than 20 kHz as ultrasonic (National Research Council [NRC], 2003; Figure 41). Measured data on the hearing
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abilities of cetaceans are sparse, particularly for the larger cetaceans such as the baleen whales. The auditory thresholds of some of the smaller odontocetes have been determined in captivity. It is generally believed that cetaceans should at least be sensitive to the frequencies of their own vocalizations. Comparisons of the anatomy of cetacean inner ears and models of the structural properties and the response to vibrations of the ear's components in different species provide an indication of likely sensitivity to various sound frequencies. The ears of small toothed whales are optimized for receiving highfrequency sound, while baleen whale inner ears are best in low to infrasonic frequencies (Ketten, 1992; 1997; 1998).

Baleen whale vocalizations are composed primarily of frequencies below 1 kHz, and some contain fundamental frequencies as low as 16 Hz (Watkins et al., 1987; Richardson et al., 1995; Rivers, 1997; Moore et al., 1998; Stafford et al., 1999; Wartzok and Ketten, 1999) but can be as high as 24 kHz (humpback whale; Au et al., 2006). Clark and Ellison (2004) suggested that baleen whales use low frequency sounds not only for longrange communication, but also as a simple form of echo ranging, using echoes to navigate and orient relative to physical features of the ocean. Information on auditory function in mysticetes is extremely lacking. Sensitivity to lowfrequency sound by baleen whales has been inferred from observed vocalization frequencies, observed reactions to playback of sounds, and anatomical analyses of the auditory system. Although there is apparently much variation, the source levels of most baleen whale vocalizations lie in the range of 150190 dB re 1 [mu]Pa at 1 m. Lowfrequency vocalizations made by baleen whales and their corresponding auditory anatomy suggest that they have good lowfrequency hearing (Ketten, 2000), although specific data on sensitivity, frequency or intensity discrimination, or localization abilities are lacking. Marine mammals, like all mammals, have typical Ushaped audiograms that begin with relatively low sensitivity (high threshold) at some specified low frequency with increased sensitivity (low threshold) to a species specific optimum followed by a generally steep rise at higher frequencies (high threshold) (Fay, 1988).

The toothed whales produce a wide variety of sounds, which include speciesspecific broadband ``clicks'' with peak energy between 10 and 200 kHz, individually variable ``burst pulse'' click trains, and constant frequency or frequencymodulated (FM) whistles ranging from 4 to 16 kHz (Wartzok and Ketten, 1999). The general consensus is that the tonal vocalizations (whistles) produced by toothed whales play an important role in maintaining contact between dispersed individuals, while broadband clicks are used during echolocation (Wartzok and Ketten, 1999). Burst pulses have also been strongly implicated in communication, with some scientists suggesting that they play an important role in agonistic encounters (McCowan and Reiss, 1995), while others have proposed that they represent ``emotive'' signals in a broader sense, possibly representing graded communication signals (Herzing, 1996). Sperm whales, however, are known to produce only clicks, which are used for both communication and echolocation (Whitehead, 2003). Most of the energy of toothed whales social vocalizations is concentrated near 10 kHz, with source levels for whistles as high as 100180 dB re 1 [mu]Pa at 1 m (Richardson et al., 1995). No odontocete has been shown audiometrically to have acute hearing (<80 dB re 1 [mu]Pa) below 500 Hz (DoN, 2001). Sperm whales produce clicks, which may be used to echolocate (Mullins et al., 1988), with a frequency range from less than 100 Hz to 30 kHz and source levels up to 230 dB re 1 [mu]Pa 1 m or greater (Mohl et al., 2000).

Table 5 includes a summary of the vocalizations of the species found in the NWTRC. The ``Brief Background on Sound'' section contained a description of the functional hearing groups designated by Southall et al., (2007), which includes the functional hearing range of various marine mammal groups (i.e., what frequencies that can actually hear). Marine Mammal Density Estimates

Understanding the distribution and abundance of a particular marine mammal species or stock is necessary to analyze the potential impacts of an action on that species or stock. Further, in order to assess quantitatively the likely acoustic impacts of a potential action on individuals and to estimate take it is necessary to know the density of the animals in the affected area. Density estimates for cetaceans were obtained from the Marine Mammal and Sea Turtle Density Estimates for the Pacific Northwest Study Area (DoN, 2007a). The abundance of most cetaceans was derived from shipboard surveys conducted by the Southwest Fisheries Science Center in 1991, 1993, 1996, 2001, and 2005 (Barlow, 1995; Barlow, 2003; Barlow and Forney, 2007). These estimates are used to develop NMFS Stock Assessment Reports (Carretta et al., 2007); interpret the impacts of humancaused mortality associated with fishery bycatch, ship strikes, and other sources; and evaluate the ecological role of cetaceans in the eastern North Pacific. In the density study, predictive specieshabitat models were built for species with sufficient numbers of sightings to estimate densities for the NWTRC (described in detail Appendix B of the Navy's application). For species with insufficient numbers of sightings, density estimates were obtained from Barlow and Forney (2007).

There are limited depth distribution data for most marine mammals. This is especially true for cetaceans, as they must be tagged atsea and by using a tag that either must be implanted in the skin/blubber in some manner or adhere to the skin. There is slightly more data for some pinnipeds, as they can be tagged while on shore during breeding or molting seasons and the tags can be glued to the pelage rather than implanted. There are a few different methodologies/techniques that can be used to determine depth distribution percentages, but by far the most widely used technique currently is the timedepth recorder. These instruments are attached to the animal for a fairly short period of time (several hours to a few days) via a suction cup or glue, and then retrieved immediately after detachment or when the animal returns to the beach. Depth information can also be collected via satellite tags, sonic tags, digital tags, and, for sperm whales, via acoustic tracking of sounds produced by the animal itself.

There are somewhat suitable depth distribution data for a few marine mammal species. Sample sizes are usually extremely small, nearly always fewer than 10 animals total and often only one or two animals. Depth distribution information often must be interpreted from other dive and/or preferred prey characteristics. Depth distributions for species for which no data are available are extrapolated from similar species.

Density is nearly always reported for an area, e.g., animals/ km². Analyses of survey results using Distance Sampling techniques include correction factors for animals at the surface but not seen as well as animals below the surface and not seen. Therefore, although the area (e.g., km²) appears to represent only the surface of the water (twodimensional), density actually implicitly includes animals anywhere within the water column under that surface area. Density assumes that animals are uniformly distributed within the prescribed area,
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even though this is likely rarely true. Marine mammals are usually clumped in areas of greater importance (and often in groups), for example, areas of high productivity, lower predation, safe calving, etc. Density can occasionally be calculated for smaller areas that are used regularly by marine mammals, but more often than not there are insufficient data to calculate density for small areas. Therefore, assuming an even distribution within the prescribed area remains the norm.

Assuming that marine mammals are distributed evenly within the water column is not accurate. The everexpanding database of marine mammal behavioral and physiological parameters obtained through tagging and other technologies has demonstrated that marine mammals use the water column in various ways, with some species capable of regular deep dives (<800 m) and others regularly diving to <200 m, regardless of the bottom depth. Assuming that all species are evenly distributed from surface to bottom is almost never appropriate and can present a distorted view of marine mammal distribution in any region.

By combining marine mammal density with depth distribution information, a more accurate threedimensional density estimate is possible. These 3D estimates allow more accurate modeling of potential marine mammal exposures from specific noise sources. Density estimates are included in Table 4.
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Brief Background on Sound

An understanding of the basic properties of underwater sound is necessary to comprehend many of the concepts and analyses presented in this document. A summary is included below.

Sound is a wave of pressure variations propagating through a medium (for the MFAS/HFAS considered in this proposed rule, the medium is marine water). Pressure variations are created by compressing and relaxing the medium. Sound measurements can be expressed in two forms: Intensity and pressure. Aco

FOR FURTHER INFORMATION CONTACT

Jolie Harrison, Office of Protected Resources, NMFS, (301) 7132289, ext. 166.