Environmental organizations have added the Navy to their lawsuit against the federal government that seeks more measures to protect whales and other marine mammals from the military's sonar use. Earthjustice and other organizations announced the addition Wednesday to their lawsuit filed in December against the National Marine Fisheries Service. The lawsuit demands that the service force the Navy to seek alternatives to its five-year plan that will intensify off the California and Hawaii coasts. Navy officials estimate its activities would have a negligible impact on marine mammal populations. Environmentalists dispute that. They favor off-limits zones to biologically sensitive areas and want the Navy to avoid training in certain spots seasonally when they are rich in marine life.