DEPARTMENT OF THE NAVY PRESENTS RECORD OF DECISION FOR SURTASS LFA SONAR TRAINING AND TESTING

Courtesy Photo | WASHINGTON (March 9, 2009) The military Sealift Command ocean surveillance ship USNS Impeccable (T-AGOS-23) is one of five ocean surveillance ships that are part of the 25 ships in the Military Sealift Command Special Mission Ships Program. Impeccable directly supports the Navy by using both passive and active low frequency sonar arrays to detect and track undersea threats. (U.S. Navy Photo/Released)  

JOINT BASE PEARL HARBOR-HICKAM, HAWAII, UNITED STATES

07.24.2026

Courtesy Story

Commander Navy Region Hawaii

JOINT BASE PEARL HARBOR-HICKAM, Hawaii — The U.S. Department of the Navy announces its decision to conduct training and testing activities, as identified in Alternative 1 (Preferred Alternative) in the Surveillance Towed Array Sensor System Low-Frequency Active (SURTASS LFA) Final Supplemental Environmental Impact Statement (SEIS)/Overseas EIS (OEIS).

This decision permits the Navy to continue utilizing SURTASS LFA sonar systems onboard surveillance ships within the Western and Central North Pacific and Eastern Indian oceans. After carefully weighing strategic military readiness against potential environmental impacts, and considering extensive public input, the Navy determined that Alternative 1 represents the course of action that best ensures national defense capabilities:

· No Fleet Expansion or Boundary Changes: Operational boundaries, geographic mitigation zones, and strict coastal standoff limits (retaining a 12-nautical-mile buffer from land) remain identical to the 2019 parameters.

· Added additional Offshore Biologically Important Areas and updated some seasonal restrictions for specific ones.

· Updating to Best Available Science: The Navy successfully updated its environmental analysis using the newest marine mammal density data, updated acoustic analysis models (NAEMO), and modern scientific literature to ensure protective measures remain highly effective.

· A Standardized Accounting of Sonar Hours: Under the new ROD, the Navy is authorized for 1,100 transmission hours annually. This does not represent an increase in training, testing, or sonar activity since 2019. Rather, it is a technical update to the way the Navy measures sonar hours. The Navy has transitioned from tracking only active "ping" duty-cycles to standardizing "duration" tracking (including quiet pauses), bringing SURTASS LFA reporting in line with all other Navy sonar systems. The actual underwater acoustic footprint remains equivalent to the 592 hours analyzed in 2019.

The SURTASS LFA Study Area (SA) overlaps with the Hawaii-California Training and Testing (HCTT) SA and the Mariana Islands Training and Testing (MITT) SA. SURTASS LFA is a long-range, all-weather, dual-component sonar system used for anti-submarine warfare. Its capabilities include long-range detection, tracking, and reporting of diesel and nuclear-powered submarines. The Navy is committed to the maximum level of mitigation measures that are beneficial and practical to implement under the Proposed Action and that are intended to avoid, minimize, or mitigate potential environmental effects during military readiness activities.

Record of Decision Availability

The Record of Decision documents for the SURTASS LFASEIS/OEIS will be available on the project website at www.nepa.navy.mil/surtass-lfa/. For additional information, please visit www.nepa.navy.mil/surtass-lfa/. Media seeking further information should contact U.S. Pacific Fleet Command Public Affairs at [e-mail], 808-471-3769; Commander, Navy Region Hawaii public affairs at 808-473-2877; Joint Region Mariana at [e-mail], 671-349-3209.

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• Date Taken: 07.24.2026
• Date Posted: 07.24.2026 15:33
• Story ID: 570700
• Location: JOINT BASE PEARL HARBOR-HICKAM, HAWAII, US