WASHINGTON - The Supreme Court ruled unanimously Wednesday that property owners have a right to prompt review by a judge of an important tool used by the Environmental Protection Agency to address water pollution.

The court sided with an Idaho couple who object to an EPA order that blocked construction of their new home near a scenic lake and threatened fines of more than $30,000 a day.

Wednesday's decision is a victory for Mike and Chantell Sackett, whose property near Priest Lake has sat undisturbed since the EPA ordered a halt in work in 2007. The agency said part of the property was a wetlands that could not disturbed without a permit.

In an opinion by Justice Antonin Scalia, the court rejected EPA's argument that allowing property owners quick access to courts to contest orders like the one issued to the Sacketts would compromise the agency's ability to deal with water pollution.

"Compliance orders will remain an effective means of securing prompt voluntary compliance in those many cases where there is no substantial basis to question their validity," Scalia said.

In this case, the couple contested the determination that their small lot contained wetlands that are regulated by the Clean Water Act, and they complained there was no reasonable way to challenge the order without risking fines that can mount quickly.

Scalia, reading a summary of his opinion in court, noted that the Sacketts have never "seen a ship or other vessel cross their yard."

The Sacketts now will be able to argue in federal court that their land should not be subject to EPA regulation, said their lawyer, Damien Schiff.

The EPA issues nearly 3,000 administrative compliance orders a year that call on alleged violators of environmental laws to stop what they're doing and repair the harm they've caused. Major business groups, homebuilders, road builders and agricultural interests all joined the Sacketts in urging the court to make it easier to contest EPA compliance orders issued under several environmental laws.

Justice Ruth Bader Ginsburg said in a separate opinion that the only issue decided by the court Wednesday is the Sacketts' ability to contest the EPA finding that their property is subject to the Clean Water Act. The court did not decide larger issues, Ginsburg said.

"On that understanding, I join the court's opinion," she said.

In another separate opinion, Justice Samuel Alito called on Congress to clear up confusion over the reach of the Clean Water Act. Alito said that federal regulators could assert authority over any property that is wet for even part of the year, not just rivers and streams.

The court's opinion "is better than nothing, but only clarification of the reach of the Clean Water Act can rectify the underlying problem," Alito said.

In 2005, the Sacketts paid $23,000 for a .63-acre lot near scenic Priest Lake. They decided to start building a modest, three-bedroom home early in 2007.

They had filled part of the property with rocks and soil, in preparation for construction, when federal officials showed up and ordered a halt in the work.

In a statement, the Sacketts praised the court for "affirming that we have rights, and that the EPA is not a law unto itself."

The Natural Resources Defense Council, which sided with EPA in this case, said the decision was relatively narrow. The court "did not open the Clean Water Act up to abuse by polluters by gutting EPA's ability to issue these orders. And it didn't question their validity," said Jon Devine, a senior attorney at NRDC.

The case is Sackett v. EPA, 10-1062.