Rep. Candice Miller, R-Mich., introduced legislation last week requiring foreign ships to unload 95 percent of their ballast water in the ocean before entering the Great Lakes, the Detroit News reported.
Her bill follows an Environmental Protection Agency decision last week not to require ships to have permits under the U.S. Clean Water Act to discharge water ballast, she said.
Environmentalists criticized EPA's move, claiming it would mean more invasive species coming into the Great Lakes.
"The rules the EPA signed pretty much left it up to the Coast Guard to do inspections, but this bill makes it mandatory," said Miller.
Water ballast from passing vessels has introduced more than a dozen aquatic plants, fish and mollusks to the Great Lakes in the last several decades.