COLUMBIA -- The battle of the ports continued Thursday with a key decision by a South Carolina oversight panel that clears an environmental hurdle for the Savannah port, a move that critics said will give Georgia a competitive edge.

S.C. Rep. Jim Merrill, R-Charleston, said the state Department of Health and Environmental Control board "sold South Carolina down the river." The board voted unanimously to grant a permit that will allow the Georgia Ports Authority to deepen the Savannah River.

Dredging the port will allow Savannah to accommodate larger container ships by 2014 from a widened Panama Canal.

Opponents promised a legal fight. A couple of Democrats pointed the finger at Republican Gov. Nikki Haley.

"We're not talking about a ditch in someone's backyard," Merrill said. "We're talking about the Savannah River. I think this is a hasty, ridiculous and ill-advised decision by them."

Merrill, a member of the ports oversight commission, said his concern is for the environment and South Carolina business interests. State leaders are working to expand the port in Charleston, which environmentalists argue is better suited for the future commerce.

Haley and Gov. Nathan Deal of Georgia see the move as regional collaboration. Haley promised Deal last month that the board would hear Georgia's position, Deal has said. Haley appoints the board.

Rob Godfrey, Haley's spokesman, said Haley trusts that the board's decision is "in the best interest of South Carolina.

S.C. Sen. Vincent Sheheen, D-Camden, wants Haley to disclose any campaign contributions that may have influenced Thursday's decision. He asked her to immediately reveal any contributions within the past six months from Georgia residents and businesses.

Haley's next campaign disclosure form, which will include donations since Oct. 10, is not due until Jan. 10.

Sheheen, who lost the governor's race to Haley last year, said the Senate should investigate whether the board was improperly influenced.

Godfrey dismissed Sheheen's comments. "Vincent Sheheen should put down the sour political grapes long enough to stop hyperventilating," he said.

Godfrey said Haley has not attended an event, fundraising or otherwise, affiliated with the Savannah port.

According to her most recent disclosure forms, Haley raised about $7,300 from Georgia donors, or 3.2 percent of her total contributions for the quarter.

Mark Lutz, a board member from Mount Pleasant and vice president of a multimedia production company, said any suggestion that the board was improperly influenced "couldn't be further from the truth." He said the board is an independent body that has the protection of the state's resources at heart.

Lutz said the decision Thursday wasn't made in haste. Decisions about the permit have been ongoing for a year. The board has been up-to-date on all of the negotiations, he said.

DHEC's board approved the permit for what advocates see as a compromise with the Army Corps of Engineers. At issue is 35 miles between the Atlantic Ocean and the Savannah port, and the potential harm port development could cause to the ecosystem, including a freshwater marsh and the endangered shortnose sturgeon fish.

The plan is for Georgia to pay for devices that will inject oxygen into the river to mitigate environmental consequences, critics said those devices, needed to preserver life in the river, put the waterway "on life support." Georgia also promises to preserve an additional 1,500 acres of marsh.

The board's decision reversed one made by the agency's staff in September to deny the corps's permit request.

The Associated Press contributed to this report.