WASHINGTON – Maine Attorney General Steven Rowe urged the Supreme Court on Tuesday to let states regulate dams that affect the quality of their rivers.

Without a say in such projects, “it will create a gaping hole in the Clean Water Act,” he warned.

Justices are considering whether the owner of hydroelectric dam projects on the Presumpscot River must get state permits because water flows through the dams.

Justice Antonin Scalia joked that “just swimming in it [river] or lying sideways” could require permits.

But other justices seemed sympathetic to Maine’s case.

“The character of the water is different below the dam and above the dam,” said Justice John Paul Stevens.

Chief Justice John Roberts said: “I don’t understand, linguistically, why this isn’t putting something into the water.”

Later, however, Roberts said that he was concerned because the outcome could have a broad impact.

S.D. Warren Co. owns the dams which provide electricity for the company’s paper mill. The company’s lawyer, William Kayatta Jr. of Portland, told justices that “the release simply continues the flow of the water.”

The court also heard arguments Tuesday in Clean Water Act cases from Michigan. It was Justice Samuel Alito’s first day on the bench.

Alito focused most of his questions on Rowe and Jeffrey Minear, the Bush administration lawyer who argued on Maine’s behalf.

Alito asked if states could make hydropower impossible and whether that is what Congress intended.

The Maine case is S.D. Warren Co. v. ME Board of Environmental Protection, 04-1527.