The ban takes effect next spring. The U.S. Environmental Protection Agency announced Monday that it would approve it, The Boston Globe reported.
"In just over a decade, we transformed our harbor from the filthiest in the nation to the cleanest," Mayor Thomas Menino said at a news conference with state and federal officials. "No discharge is another part of our effort make sure that Boston Harbor is the cleanest harbor in America."
Boaters would have to go 3 miles from shore to dump sewage, use a shore pumping station or take advantage of the sewage boats provided by the city.
Rhode Island and Connecticut already have state-wide bans on dumping within 3 miles of shore. Massachusetts has eight no-dumping zones, most of them on Cape Cod and plans a state-wide dumping ban in 2009.