The U.S. Environmental Protection Agency's new rule will take effect early next year and adds teeth to existing state law, which already bans ships from dumping runoff from their showers or sinks, oil or other hazardous substances.
Regional EPA Administrator Jared Blumenfeld said cruise ships and other vessels dump 20 million gallons of sewage off California's coast each year, which ends up fouling beaches and bays.
Some cruise ships can hold 6,000 passengers, so a lot of sewage can be dumped from just one vessel. The refuse ends up being jettisoned into the sea, and if close enough to shore can affect water quality at beaches, leading to closures.
Michael Crye, executive vice president of Cruise Lines International Association, said its members already follow discharge regulations exceeding the new standards. The group represents 25 companies, including Carnival and Disney Cruise Lines.
"Our vessels have been following industry wide practices and California state law. They don't discharge within three miles of the California coast, and have been following that for a number of years," Crye said.
But the new rule doesn't just target cruise liners. Large container vessels bringing goods into port also would be covered by the regulation, which will apply to all vessels of 300 gross tons or more.
"California is a hub for international trade, with ports in Los Angeles, Long Beach and Oakland. So a lot of sewage ends up in our waters for goods that end up in Chicago and New York," Blumenfeld said.
Even though the state's measure originally included sewage, regulating that discharge falls under the jurisdiction of the federal Clean Water Act, so EPA had to take the lead on controlling it.
The new rule allows the U.S. Coast Guard to cite vessels for violations.
The rule applies to all sewage discharges, treated or not.