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.

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.