Five North Shore communities and three south of Boston are moving closer to becoming No Discharge Areas, a federal designation that prevents boaters from dumping sewage overboard in local waters.Most boats 20 feet or longer are equipped with a toilet and a Y-valve, which can divert waste into an onboard holding tank or directly into the sea. The latter method can produce fetid conditions, particularly in marinas or harbors, as well as pollute recreational beaches.Although many conscientious boaters would voluntarily contain their waste, they are forced to release it overboard when no pump-out station is available. That situation is changing along much of the coast as additional pump-out stations are established, capable of vacuuming holding tank waste for a small fee.The Salem Sound Coastwatch communities of Salem, Marblehead, Danvers, Beverly and Manchester-by-the-Sea, are eagerly anticipating that the U.S. Environmental Protection Agency (EPA) will approve their collective application for designation as a No Discharge Area.The application was first submitted to the state Executive Office of Energy and Environmental Affairs (EEA), where it met with approval and earned a recommendation from the state Office of Coastal Zone Management (CZM). Earlier this week, EEA Secretary Ian Bowles forwarded the application to the EPA. If approved by the federal agency, the designation would prohibit boats from discharging all sewage – including treated waste – in the waters of Salem Sound.Proponents of the plan say the No Discharge Area designation will protect eelgrass beds, shellfish and other marine life, and help keep recreational beaches free from pathogens, chemicals and substances found in discharged sewage.In March, the communities of Cohasset, Scituate and Marshfield together filed for similar designation as the state’s ninth No Discharge Area.Plymouth, Kingston, Duxbury and Harwich already received approval, as did Buzzards Bay, Falmouth, the Three Bays and Centerville Harbor in Barnstable, parts of Chatham, Wellfleet, and the northern waters off Nantucket.On the North Shore, the communities of Lynn, Nahant, Swampscott, Saugus and Revere have discussed banding together to submit an application to become a No Discharge Area, but the effort has not been agreed upon.”Officials from those communities have been in touch with CZM to begin the process and get some technical assistance,” said Lisa Capone, spokesman for the EEA in Boston.Jamie Marsh, aide to Lynn Mayor Edward Clancy Jr., confirmed as much. “Nothing has been signed yet, but there have been discussions,” he said.Should the various municipal officials agree to submit an application, the designation could come just as Lynn is attempting to revitalize its harbor with a waterfront master plan.”It’s still in the early stages, and doesn’t seem to be on anyone’s front burner, but it’s an important step,” said Nahant resident Polly Bradley, founder and member of the environmental advocacy group Safer Waters in Massachusetts (SWIM). “(Nahant Town Administrator) Mark Cullinan and others have been gathering information and so far, nobody is against it.”SWIM President Julie Arnold said Cullinan has completed the necessary paperwork for Nahant and is attempting to obtain similar documentation from the other communities. “It’s moving along slowly, but it’s moving,” Arnold said.According to Robert Varney, EPA regional administrator, the Salem Sound communities created seven pump-out facilities, upgraded coastal sewer systems and implemented stormwater management practices. Public pump-out stations are usually paid for with about 80 percent of state funds. Some marinas and yacht clubs also provide pump-out services, but usually for a fee.Todd Callaghan at the EEA in Boston said plans are nearing completion that will designate Boston Harbor and all of Cape Cod Bay as No Discharge Areas. The communities of Cape Ann, from Gloucester to the New Hampshire border, have not indicated any intention