Surveillance Towed Array Sensor System (SURTASS) Low Frequency Active (LFA) Sonar is a long range surveillance sonar the U.S. Navy requires for national security.

The Department of the Navy, with the National Marine Fisheries Service as a cooperating agency, has prepared a Supplemental Environmental Impact Statement/Supplemental Overseas Environmental Impact Statement (SEIS/SOEIS) for SURTASS LFA sonar in accordance with the National Environmental Policy Act and Executive Order 12114. The SEIS/SOEIS evaluated the potential environmental impacts associated with two action alternatives and a No-Action Alternative to the following resource areas: air quality, marine environment, biological, and economic. The 2019 Final SEIS/SOEIS is available for download here. After a 30 day public comment period, the Navy selected Alternative 2, the Preferred Action Alternative, which is documented in its Record of Decision, available for download here.

As part of the environmental decision-making process, the Navy submitted an application for rulemaking and a letter of authorization under the Marine Mammal Protection Act (MMPA) to take marine mammals incidental to the use of SURTASS LFA sonar for training and testing activities in the western and central North Pacific and eastern Indian oceans. Additionally, the Navy submitted a Biological Evaluation to initiate Section 7 consultation under the Endangered Species Act (ESA). In its ESA Biological Opinion, NMFS determined that the proposed action is not likely to jeopardize the continued existence of threatened and endangered species under NMFS’s jurisdiction and is not likely to destroy or adversely modify designated critical habitat over the period of the proposed seven-year MMPA rule and letter of authorization, and into the reasonably foreseeable future. The Biological Opinion, which includes the Incidental Take Statement, was signed on July 30, 2019, becoming effective when the MMPA Final Rule and LOA are authorized; it is available for download here. The MMPA Final Rule and LOA are expected to be authorized in early August 2019.

On August 10th, 2017, the Deputy Secretary of Defense invoked a National Defense Exemption (NDE), as he is authorized to do under the Marine Mammal Protection Act (MMPA), for continued SURTASS LFA sonar testing, training and operations. The Navy developed and employs SURTASS LFA sonar to meet the need for detecting quiet submarines at long range, and the system is critical to the national defense. The current MMPA “Final Rule” for SURTASS LFA sonar activities expires on August 14, 2017. The NDE will run for two years, or until a new Final Rule is issued, whichever comes first. The NDE will provide additional time for the National Marine Fisheries Service (NMFS) and Navy to consider and address issues raised in the rulemaking process. During the exemption period, the Navy will continue to comply with all mitigation and monitoring measures that were included in the proposed MMPA rule plus additional mitigation measures the Navy agreed to after its publication. NMFS issued a biological opinion for the SURTASS LFA sonar activities on August 11, 2017. Download NDE here.

Please see the Frequently Asked Questions page where answers to some commonly asked questions on the NDE are addressed. Additional questions should be directed to the Navy News Desk, (703) 697-5342.