A federal judge ruled Wednesday that the Army Corps of Engineers' failure to properly maintain a navigation channel led to massive flooding in Hurricane Katrina, a decision that could make the federal government vulnerable to billions of dollars in claims.

U.S. District Judge Stanwood Duval sided with six residents and one business who argued the Army Corps' shoddy oversight of the Mississippi River-Gulf Outlet led to the flooding of New Orleans' Lower 9th Ward and neighboring St. Bernard Parish. He said, however, the corps couldn't be held liable for the flooding of eastern New Orleans, where two of the plaintiffs lived.

Duval awarded the plaintiffs $720,000, but the government could eventually be forced to pay much more in damages. The ruling should give more than 100,000 other individuals, businesses and government entities a better shot at claiming billions of dollars in damages.

The ruling is also emotionally resonant for south Louisiana. Many in New Orleans have argued that Katrina, which struck the region Aug. 29, 2005, was a manmade disaster caused by the Army Corps' failure to maintain the levee system protecting the city.

"Total devastation could possibly have been avoided if something had been done," said Tanya Smith, one of the plaintiffs. "A lot of this stuff was preventable and they turned a deaf ear to it."

The 36-year-old registered nurse anesthetist lived in Chalmette close to the channel when Katrina hit. She was awarded $317,000 in property damages, the most of any of the plaintiffs.

Duval referred to the corps' approach to maintaining the channel as "monumental negligence."

Joe Bruno, one of the lead lawyers for the plaintiffs, said the ruling underscored the Army Corps' long history of not properly protecting the New Orleans region.

"It's high time we look at the way these guys do business and do a full re-evaluation of the way it does business," Bruno said.

He said he expected the government to appeal.

The corps referred calls seeking comment to the Justice Department, which didn't immediately return a message left Wednesday night.

During trial testimony, government lawyers and experts argued the levee system was overwhelmed by the massive storm, and levee breaches couldn't solely be blamed on the shipping channel dug in the 1960s as a short-cut between the Gulf of Mexico and New Orleans.

The corps had also unsuccessfully argued that it is immune from liability because the channel is part of New Orleans' flood control system.

In his 156-page ruling, Duval said he was "utterly convinced" that the corps' failure to shore up the channel "doomed the channel to grow to two to three times its design width" and that "created a more forceful frontal wave attack on the levee" that protected St. Bernard and the Lower 9th Ward.

"The Corps had an opportunity to take a myriad of actions to alleviate this deterioration or rehabilitate this deterioration and failed to do so," Duval said. "Clearly the expression 'talk is cheap' applies here."

The corps has been sued before over levee failures and flooding, but it had always walked away untouched. That included after Hurricane Betsy in 1965 over alleged flooding by the outlet. Ahead of Duval's ruling, experts had said it would likely have consequences for the way the Army Corps does business nationwide.

Pierce O'Donnell, another lead plaintiffs lawyer, said the ruling was the "first time ever the Army Corps has been held liable for damages for a major catastrophe that it caused."

The plaintiffs lawyers would like Congress to set up a compensation fund to speed up payments to the thousands of other claimants, whose claims must still be heard in court.

At a one-month trial in May, experts clashed over the causes of flooding and the channel's contribution to it.

Government experts argued the levees and floodwalls would have failed regardless of whether the MRGO had been dug.

By contrast, the plaintiffs' team of experts said the outlet became a "hurricane highway" that funneled storm surge into New Orleans. They said that without the channel, the flooding would have been minimal.

The lawsuit was the first major case against the federal government over Katrina flooding to go to trial. A decision rested with Duval because a jury cannot try a case against the federal government.

Despite its statements in court, the corps has acknowledged the area's flood risk and closed the channel with rocks. It is also building a $1.3 billion floodgate to stop surge entering the city from the direction of the channel and Lake Borgne.