The U.S. Navy prepared the Final Environmental Impact Statement/Overseas Environmental Impact Statement (EIS/OEIS) to assess the potential environmental impacts associated with proposed military training and testing activities in the Hawaii-Southern California Training and Testing (HSTT) EIS/OEIS Study Area. The Navy previously completed an EIS/OEIS in December 2013 for training and testing activities occurring within the Study Area from 2013 to 2018; this updated analysis will support future activities beginning in late 2018. In this Final EIS/OEIS, the Navy evaluated new, relevant information, such as more recent marine mammal density data and new scientific information, and updated the environmental analyses as appropriate.

The Proposed Action is to conduct Navy training and testing activities within the Study Area. These activities include the use of active sonar and explosives while employing marine species protective measures. Proposed training and testing activities are similar to the types of activities that have occurred in the Study Area for decades and are generally consistent with those analyzed in the 2013 Final EIS/OEIS and earlier environmental planning documents. The purpose of the Proposed Action is to maintain a ready force, which is needed to ensure the Navy can accomplish its mission to maintain, train, and equip combat-ready naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas, consistent with Congressional direction in Section 8062 of Title 10 of the U.S. Code.

To achieve and maintain military readiness, the Navy proposes to:

• Conduct training and testing activities at levels required to support future Navy military readiness requirements beginning in late 2018; and
• Accommodate evolving mission requirements, including those resulting from the development, testing, and introduction of new vessels, aircraft, and weapons systems into the fleet.

The HSTT EIS/OEIS considers a No Action Alternative and two action alternatives that account for types and tempo of training and testing activities.

No Action Alternative – Under this alternative, the Navy would not conduct proposed training and testing activities, and a permit under the Marine Mammal Protection Act would not be issued. This alternative does not meet the purpose and need for the proposed action.

Alternative 1 – Under this alternative, the Navy would conduct training and testing activities needed to meet current and future readiness requirements, while better reflecting how unit level active sonar training events are typically conducted (e.g., through simulation or concurrently with major training exercises).

Alternative 2 – Under this alternative, the Navy would conduct training and testing activities to enable the Navy to meet the highest levels of required military readiness, but would assume unit level active sonar training would be completed through discrete events and not through the use of synthetic training. Additionally, this alternative includes a contingency for an increased amount of weapon system tests in response to potential increased world conflicts and changing Navy leadership priorities.

The range complexes analyzed in this EIS/OEIS have each existed for many decades, dating back to the 1930s. Range use and infrastructure have developed over time as military readiness requirements in support of modern warfare have evolved.

Proximity of the Hawaii and Southern California Range Complexes to naval homeports and air stations is strategically important to the Navy. Close access allows for efficient execution of military readiness activities including maintenance functions, as well as access to alternate airfields when necessary, in order to provide for a margin of safety. Fuel is saved and equipment is exposed to less wear when ranges are near where the platforms are based. The proximity of training to homeports also ensures that Sailors and Marines do not spend unnecessary time away from their families during the training cycle.

The Navy is committed to providing continued access to surface water areas and airspace off the Southern California coast and around the Hawaiian Islands to other commercial and recreational users in the Study Area. However, for the public's safety, the use of certain ocean areas may need to be temporarily limited during some training and testing activities.

• The United States Coast Guard and Department of Homeland Security inform the commercial and private vessel about temporary closures via Notices to Mariners.
• The Federal Aviation Administration issues Notices to Airmen to disseminate information on upcoming or ongoing military exercises with resulting airspace restrictions.