The U.S. Senate on Wednesday voted down the Coast Guard reauthorization bill that contained a provision exempting ships' ballast water from Clean Water Act regulations.

The Senate vote on cloture - whether to stop debate and vote on the bill - needed 60 votes but failed by a 56 to 42 margin.

The bill contained the controversial Vessel Incidental Discharge Act that would have exempted ships from Environmental Protection Agency regulation and instead given ballast water regulation authority solely to the U.S. Coast Guard.

The bill would have also prohibited states from enforcing their own ballast rules.

Ballast water can contain aquatic invasive species that are moved from faraway ports into the U.S. and can cause both economic and environmental damage as they spread.

Shipping industry officials say they should not be subjected to Clean Water Act regulations, supporting instead a single, national ballast standard enforced only by the Coast Guard.

Critics of the bill say the shipping industry should be treated as any other industrial polluter. A 2006 federal court ruling agreed, but the legislation would have overruled that court decision.

"Today's vote by the Senate brought a sigh of relief for the Great Lakes region. The U.S. Senate stood up to protect the Great Lakes," said Jennifer Caddick, spokesperson for the Alliance for the Great Lakes. "This means Clean Water Act protections will continue to apply to ballast water discharges, which are the main pathway for aquatic invasive species introductions into the Great Lakes."

Several senators from Great Lakes states voted to block the bill, including Minnesota Democrats Amy Klobuchar and Tina Smith and Wisconsin Democrat Tammy Baldwin.