The US Navy have released their final Environmental Impact Statement (EIA) on a security system to make make sure that no swimmers or divers are able to enter the Naval Base Kitsap-Bangor via Hood Canal waters. It will announce shortly which of five options it selects.

However,its preferred alternative remains the combination of its Atlantic bottlenose dolphins and California sea lions. Other choices include the sea lions only, combat swimmers or remotely operated vehicles.

The reason that the Navy prefers the marine mammal option is because the dolphins' sonar is simply better for detecting objects and that the animals can cover a lot of water quickly. Sea lions aren't quite as good, but they can see and hear well underwater. They are however better for shallower work around piers.

The point of an EIA is to evaluate the potential environmental consequences to a proposed project and this recent final EIS differs from the draft EIS only in its inclusion of comments made to the draft in February and March, and the Navy's responses, said Navy spokeswoman Sheila Murray.

The final EIS with appendices can be viewed here