Proposed Action


Proposed Action

The Navy is not proposing new training activities or increasing activities from current levels. The Navy's proposed training activities have occurred in the Study Area for decades.

The Navy's Proposed Action is the same as presented in the 2011 Gulf of Alaska Final EIS/OEIS and the 2016 Gulf of Alaska Final Supplemental EIS/OEIS, which is to continue periodic military training activities within a Temporary Maritime Activities Area in the Gulf of Alaska. Proposed activities include the continued use of active sonar and weapon systems that may use non-explosive or explosive munitions at sea. These activities would be performed while employing marine species mitigation measures. The Temporary Maritime Activities Area and Proposed Action, including the location, number, and frequency of major training exercises, remain unchanged from the 2016 impact analysis.

In the Supplemental EIS/OEIS, the Navy will include the analysis of at-sea activities projected to meet readiness requirements beyond 2022 and into the reasonably foreseeable future, which reflects the most up-to-date compilation of training activities deemed necessary to accomplish military readiness requirements.

Purpose of and Need for the Proposed Action

The Supplemental EIS/OEIS is an update to the 2011 and 2016 impact analyses to support naval training requirements to achieve and maintain fleet readiness as required by Title 10 of the U.S. Code.

Importance of Realistic Training

Realistic training activities are crucial for military readiness, personnel safety, and national defense.

Sailors must be ready to respond to many different situations when called upon. The skills needed to achieve readiness are challenging to master and require constant practice. Training must be diverse and as realistic as possible to prepare Sailors for what they will experience in real-world situations and ensure their success and survival. Although some training may be accomplished in simulation, there is no substitute for live training to achieve final training qualifications.

Northern Edge exercises are Alaska’s largest joint training exercises and occur biennially (typically every other year in odd years). The Navy has participated in Northern Edge exercises since the 1990s. These exercises are designed to replicate challenging scenarios and prepare service members to respond to crises, such as natural disasters, global conflicts, and threats to homeland security.

Importance of Training with Active Sonar and Weapon Systems

The Navy proposes to continue training activities, which include the use of active sonar and weapon systems that may use non-explosive or explosive munitions. The Navy would employ marine species mitigation measures during these activities.

One of the Navy's top priorities is to defend against enemy submarine activity. The Navy uses both passive and active sonar to detect potentially hostile submarines. Torpedoes, in-water mines, and quieter submarines from hostile sources are true threats to global commerce, national security, and the safety of Sailors. Active sonar is the most effective method of detecting these threats. Sonar proficiency is complex and requires regular, hands-on training in realistic and diverse conditions.

Training at sea with explosives significantly enhances the safety of U.S. forces in combat and improves readiness and equipment reliability. Sailors must train in a variety of high-stress environments, including scenarios that involve the use of and exposure to explosive ordnance, to be prepared to respond to emergencies and national security threats.



Sonar Previous generation submarines were noisy and could be detected with passive sonar before they came close enough to deploy short-range weapons against a vessel. Extremely quiet, difficult-to-detect, diesel-electric submarines can approach close enough to deploy long-range weapons before entering a U.S. vessel’s passive sonar detection range. Active sonar has a longer detection range that is needed to allow Navy Sailors to detect, identify, and track quieter, modern submarines before they are close enough to attack.


The National Environmental Policy Act (NEPA) requires federal agencies to evaluate a range of reasonable alternatives to achieve the purpose of and need for the Proposed Action. In the Supplemental EIS/OEIS, the Navy will evaluate the potential environmental effects of a no action alternative, in which the National Marine Fisheries Service would not issue Marine Mammal Protection Act authorization, and an action alternative in which the Navy would reanalyze Alternative 1 from the 2016 GOA Final Supplemental EIS/OEIS.

Key Updates from the 2016 Final Supplemental EIS/OEIS

Proposed training activities are similar to those that have occurred in the Gulf of Alaska for decades and are consistent with those analyzed in the 2011 and 2016 impact analyses. In the upcoming Supplemental EIS/OEIS, the Navy will:

  • Include a No Action Alternative in which the National Marine Fisheries Service would not issue Marine Mammal Protection Act authorization; therefore, proposed training activities would not occur.
  • Reanalyze Alternative 1 from the 2016 GOA Final Supplemental EIS/OEIS; training activities would not increase from current authorized levels in the Gulf of Alaska.
  • Include improved acoustic models, updated marine mammal densities, and updated marine species criteria and thresholds.
  • Use the most current and best available science and analytical methods. 
  • Review procedural mitigation measures, where appropriate, and consider additional geographic and/or temporal mitigation measures, where applicable.
USS Theodore Roosevelt (CVN 71)
Search and Rescue
Search and Rescue