Commercial vessels are equipped with tanks that can hold millions of gallons of water to provide stability in rough seas. But live creatures often lurk in the soupy brews of water, seaweed and sediment. If they survive transoceanic journeys and are released into U.S. waters, they can multiply rapidly, crowding out native species and spreading diseases.
Ships are currently required to dump ballast water 200 miles from a U.S. shoreline. But under the new general permit released by the EPA, vessels longer than 79 feet—which includes an estimated 60,000 vessels—must also treat ballast water with technology such as ultraviolet light or chemicals to kill at least some of the organisms.
The new guidelines don't apply to vessels staying within the Great Lakes, a decision that environmentalists criticized as leaving the door open for ships to ferry invasive species around the lakes.
The permit imposes international cleanliness standards that the Coast Guard also adopted in regulations it issued last year. The EPA said studies by its science advisory board and the National Research Council endorsed the standards, which limit the number of living organisms in particular volumes of water.
Environmental groups contend the limits should be 100 or even 1,000 times tougher, but industry groups say no existing technology can go that far.
"The numeric limitations in today's permit represent the most stringent standards" that ballast water treatment systems can "safely, effectively, credibly, and reliably meet," the EPA said in a statement with the 200-page report it released on the permit late Thursday.
But environmental groups, whose lawsuits forced the EPA to adopt ballast discharge standards in the first place, said they're too weak.
"The EPA had an opportunity to lead the world in solving this globally dangerous problem, but they have missed the mark ... again," said Mary Ellen Ashe, executive director of Great Lakes United.
She also criticized the EPA for exempting ships that never leave the Great Lakes, where ballast water is blamed for introducing invasive species including zebra and quagga mussels. Those organisms have spread across the lakes, clogging water intake pipes and unraveling food webs by gobbling microscopic plankton on which fish depend.
Environmentalists contend that those exempted ships can carry exotic species around the lakes even if they weren't responsible for bringing them to the U.S. The EPA said treatment technologies are "unavailable and economically unfeasible" for those vessels. But it said any built before 2009 would have to take other steps such as limiting the amount of ballast water they pick up near shore.
Under the EPA permit and the Coast Guard regulations, ships built after Dec. 1 will have to comply with the treatment standards immediately. The requirements will be phased in for existing vessels over several years, with treatment technology being installed as ships are taken out of service for maintenance.
A coalition of environmental groups said there should be a hard deadline to retrofit all existing ships. But the EPA contends that a faster pace isn't feasible because the ballast treatment industry needs time to produce the equipment and vessel owners must develop schedules for dry-docking them to have the work done.
The EPA refused for years to set rules for ballast water under the Clean Water Act, but was ordered to do so by federal courts after environmental groups sued. The agency issued an industry-wide permit in 2008 requiring shippers to exchange their ballast water at sea or, if the tanks were empty, rinse them with salt water before entering U.S. territory in hopes of killing freshwater species inside. Environmentalists sued again, saying those requirements were inadequate.
They may return to court yet again, said Marc Smith, senior policy manager for the National Wildlife Federation's Great Lakes office.
"We're disappointed that EPA has punted instead of taking its responsibilities seriously," Smith said. "We're currently assessing all options, including any kind of legal recourse or working through Congress."
Legislation on ballast water has been introduced previously in Congress but got bogged down amid disagreements over how strict the cleanliness standards should be.