TRAVERSE CITY, Mich. - Michigan lawmakers were poised Wednesday to weaken a policy that prohibits oceangoing cargo ships from releasing ballast water at the state's ports until it has been treated to kill invasive species.

A Senate committee voted to revise a 2005 law requiring saltwater vessels to use state-approved cleansing technology before discharging ballast water, which provides stability in rough seas. Scientists believe dozens of the invasive species that have reached the Great Lakes in recent decades, including zebra and quagga mussels and round gobies, arrived in ballast water.

Michigan would adopt federal treatment standards under the bill, which was scheduled for a Senate floor vote Thursday. It cleared the House last week.

Its sponsor, Republican Rep. Dan Lauwers of St. Clair County's Brockway Township, contends the Michigan policy makes its shipping industry less competitive, sending oceangoing export business to other Great Lakes states. It also causes greater use of trucks, he said.

"Our current regulations were seen as environmentally friendly, but one ship can carry on average what it would take about 60 trucks to carry," Lauwers said in a statement on his website. "We need to eliminate this overregulation and utilize our deep water ports to bring back jobs and protect our roads."

Environmentalists described the measure as "a significant step backward" in shielding Michigan waters from invasive species, which out-compete native fish, unravel food chains and do billions of dollars' worth of economic damage.

"By weakening these standards, the likely consequence is new invasive species entering the ecosystem which put our recreation and commercial fisheries at risk," said James Clift, policy director of the Michigan Environmental Council.

Under existing regulations, oceangoing vessels can get a permit to discharge ballast in Michigan waters by using any of several approved ballast treatment systems. Ships without such systems can pick up or unload freight at Michigan ports but can't release their ballast water.

The U.S. Coast Guard and the U.S. Environmental Protection Agency require ships to exchange ballast water at sea before entering U.S. waters. Scientists said that process can get rid of some invasive species, but others can survive it.

The Coast Guard also has instructed ships to phase in treatment systems. But in the meantime, the pending bill would allow them to dump untreated ballast water in Michigan, said Charlotte Jameson of the Michigan League of Conservation Voters.

Gov. Rick Snyder opposes the bill, spokeswoman Anna Heaton said, adding that it was too soon to say whether he would veto it because changes might be made.

Spokeswoman Tiffany Brown said the state Department of Environmental Quality also opposes it.

News from © The Associated Press, 2017