The U.S. House passed a bill Tuesday that would create a national standard for cleaning ballast water in ships.
Ballast water has been the main pathway for invasive species like zebra mussels into the Great Lakes.
The law would adopt the International Maritime Organization's proposed rule, which would require ocean-going ships to install technology to limit the number of live organisms in their ballast water. It was referred to the Senate Committee on Commerce, Science, and Transportation.
Steve Fisher, executive director of the American Great Lakes Ports Association, said a national standard is needed to replace the current regulatory patchwork.
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"We've got two federal agencies, more than 26 different state rules on governing the ballast water discharges from vessels, and two Indian tribes, all regulating the same thing," he said. "That was creating regulatory chaos."
The new standard wouldn't go far enough if it were to pass into law, said National Wildlife Federation senior policy manager Marc Smith.
"Most troubling is that it prevents states and the Environmental Protection Agency from setting protective and effective standards, basically it preempts the states from going more stringent than what this standard is," Smith said.
New York has passed a law that sets live organism limits 100 times tougher than current standards. But shipping companies say the technology doesn't exist yet to meet it.