Most marine animals use sound to navigate, feed, find mates and communicate with each other when in deep waters. The Navy has been very insistent that they can use an ultra-loud sonar that is safe for marine life. They have been convincing the courts for over a decade. However those tides have changed. On July 15, the Ninth US Circuit Court of Appeals in San Francisco ruled that the Navy's technology is not safe at all.
The ruling came down to an interpretation of the National Marine Protection Act leaning towards the Navy's side, which prohibits any US citizen or organization to harm marine creatures such as dolphins, whales, and seals. National Oceanic and Atmospheric Administration (NOAA) Fisheries Service made the ruling, which put them in league with the said agency making the Natural Resources Defense Council (NRDC) and several co-defendants take NOAA to court, and eventually win. This results to the Navy being prohibited from using its deep submarine sonar.
Although there is no real threat for the US Navy, they wanted to develop long-range sonar tools to keep enemies from getting closer. This technology coupled with the current noise pollution of oil drilling and marine shipping increased the burden on marine life.
The US Navy created the Surveillance Towed Array Sensor System Low Frequency Active or SURTASS/LFA. It emits loud and low-frequency sounds at around 100 to 500 Hertz, also the range that marine mammals use to communicate and survive.
Marine animals sometimes mistake the sounds from the sonar as a threat, which make them respond accordingly. This causes injuries and in some cases led to death.
In the ruling, the court declared that NOAA should be overprotective of marine mammals and they must make sure that the Navy only operates the sonar array in mammal-free waters.