The National Marine Fisheries Service is in hot water following its authorization of the U.S. Navy's use of sonar during naval exercise.

Environmental groups have filed a lawsuit against the National Marine Fisheries Service, saying that it violated the federal law when it authorized the Navy's use of sonar in training exercises. The environmental groups claim that the exercise is harming marine mammals. The lawsuit was filed on Monday, January 27, at a federal court in San Francisco by groups led by the Natural Resources Defense Council.

The Natural Resources Defense Council filed the lawsuit on behalf of five environmental organizations. Earthjustice, filed a similar suit last week in Hawaii on a behalf of five other groups.

In December 2013, the National Marine Fisheries Service sanctioned Navy sonar training exercises off the coasts of California and Hawaii through 2018. According to the Natural Resources Defense Council, the authorization came even though the Navy had admitted that this would result in the death of nearly 155 marine mammals like whales and dolphins, as well as cause over 2,000 lasting injuries. The sonar training exercise would also cause disruption to mammals' natural activities and even result in 9.6 million instances of temporary hearing loss.

Per the lawsuit, the anti-submarine and amphibious warfare exercises that are slated to have close to 60,000 hours of sonar broadcasts, as well the detonation of more than 250,000 explosives, would harm the endangered blue whales and beaked whales.

Apparently, the National Marine Fisheries Service has authorized up to 10 beaked whale and 13 blue whale deaths, owing to the Navy exercises.

"This is an unprecedented level of harm," said Zak Smith, an attorney with the Natural Resources Defense Council, to the Los Angeles Times. "In order to authorize these impacts on marine mammals, the service had to turn its back on the best available science."

The lawsuit accuses the National Marine Fisheries Service of breaching the Marine Mammal Protection Act. The lawsuit also asks that the authorization by the National Marine Fisheries Service be voided and reconsidered. Moreover, it also asks that the Navy be made to obey state and federal environmental laws and that training be restricted in specific regions and times.

The Navy and National Marine Fisheries Service defends their stand by saying that they have established "practical and reasonably effective" safety measures meant to safeguard marine mammals. These include reducing the power of the sonar and even shutting it down when whales are spotted in the vicinity.