TRAVERSE CITY, Mich. (AP) -- Shipping companies, scientists and environmentalists have long debated how to stop the onslaught of exotic species such as zebra mussels in the Great Lakes. Now, lawyers are getting involved.
Many of the 183 invasive species known to inhabit the lakes arrived in ballast water dumped by oceangoing ships. A Michigan law that took effect this year requires freighters to sterilize ballast before discharging it into the state's waters.
State legislators say they grew tired of waiting for the industry and federal regulators to slam the door on invasives, a threat to the ecosystem and a huge drain on the regional economy. But a shipping coalition recently sued in federal court in Detroit, saying the law makes unreasonable demands and violates the U.S. Constitution by restraining interstate commerce.
"We fully support dealing with this problem and we're the ones pumping millions into research to find the solution," said John Jamian, president of the Seaway Great Lakes Trade Association. A mechanism for killing invasives in ballast may be ready to install on ships as soon as next year, he said.
"But you can't have Michigan imposing a specific technology that most likely will not be accepted by other Great Lakes states, let alone other U.S. states and countries," Jamian added.
Several environmental groups are asking to join the suit on Michigan's side.
"It's absurd to suggest that the states and local communities can't protect the biological integrity of the Great Lakes," said Henry Henderson, the Natural Resources Defense Council's Midwestern director.
States have a history of regulating pollution -- auto emissions, mercury from power plants -- when they believe the federal government isn't doing enough.
But critics say it makes no sense to go it alone on ballast regulation. The five Great Lakes are linked by rivers and canals. Foreign species released at one port can reproduce and spread on their own or aboard other vessels.
Eight states and two Canadian provinces claim jurisdiction over portions of the lakes.
"If each state has its own program and a vessel has to come into Michigan and do one thing, then go to Wisconsin and have to do something else, that can be confusing," said Bivan Patnaik, environmental regulation coordinator for the U.S. Coast Guard, the federal agency in charge of ballast rulemaking.
It may come to that. Bills similar to Michigan's are pending in the Minnesota and Wisconsin legislatures.
"We fully acknowledge that in order for it to be effective, we'll need to get the other Great Lakes states on board," said Robert McCann, spokesman for the Michigan Department of Environmental Quality. "Michigan decided we need to be a leader on this. We can't wait any longer."
Oceangoing freighters take on ballast -- water laced with sediment, seaweed and other detritus -- for stability when traveling without cargo. They empty the tanks after reaching ports for loading.
Living creatures are hauled across oceans in ballast tanks and released in different environments. Some outcompete native species, disrupting food webs and other natural systems.
Invaders also have reached the lakes through canals or were intentionally released. But Michigan officials and some scientists contend ballast is the primary culprit.
Coast Guard regulations require salt-water freighters to exchange ballast before entering U.S. territory -- or keep it onboard. But ships hauling cargo can get around the requirement by declaring they have no ballast on board.
Those ships might still have residue in their tanks harboring living organisms that could escape into the lakes. The Coast Guard encourages -- but doesn't require -- them to flush ballast tanks at sea.
The agency said in 2002 it would develop new federal standards for all vessels operating in U.S. waters. It plans to issue a draft environmental analysis and take public comment this year, Patnaik said. He declined to say when the updated regulations would be finished.
"It's a very technically challenging, complicated issue," Patnaik said.
The Coast Guard acknowledges the National Invasive Species Act allows states to write their own ballast rules. But the shippers' lawsuit contends state laws are pre-empted by federal regulations on ship operations.
Under the Michigan law, any oceangoing ship calling at one of its ports must obtain a DEQ permit. Those intending to discharge ballast must show they use "environmentally sound technology and methods" to kill invasive species before release.
The DEQ has issued permits to 20 ships since the law took effect in January, McCann said. All said they would not discharge ballast in Michigan waters.
Only four of about 100 oceangoing vessels that visited the state's ports last year released ballast and would need sterilization equipment to get a permit, Jamian said.
But there's no foolproof way to zap exotics inside ballast tanks, despite years of research and experimentation, he said.
A promising method being tried on a Great Lakes freighter this summer would pump nitrogen into ballast water to remove its life-giving oxygen, Jamian said. If successful, ships might start using it in 2008. Other possibilities include treatment with chemicals or ultraviolet light.
Even after a workable system is devised, equipment must be manufactured and ships retrofitted. Deoxygenation gear probably would cost $250,000 to $1 million per ship, Jamian said.
That's a small price for stemming the aquatic invasion, say supporters of the Michigan law.
Damage from zebra and quagga mussels, which clog municipal water intake pipes, exceeds $150 million a year. The region's $4 billion fishery suffers from competitive outsiders such as the round goby and a recently arrived virus blamed for fish kills in Lakes Ontario, Erie and Huron.
"Preventing pest species from coming into the Great Lakes is so much cheaper, easier and more effective than trying to undo the damage once it's been created," said Cameron Davis, president of the Chicago-based Alliance for the Great Lakes.
Pollutants such as chemicals and sewage can be cleaned up, said David Lodge, director of the Center for Aquatic Conservation at Notre Dame University. But exotic species invasions are usually irreversible.
"Once a species has been introduced and establishes itself ... it will continue to grow and spread, not only in the Great Lakes but across the waterways of North America," Lodge said.