A landmark court ruling blaming the Army Corps of Engineers' "monumental negligence" for some of the worst flooding from Hurricane Katrina could lead to a new deluge: billions of dollars in legal action from thousands of storm victims.

The federal judge's harshly worded decision also served as vindication for residents of St. Bernard Parish and the Lower 9th Ward in New Orleans, who have long argued that Katrina was largely a man-made disaster, caused by the federal government's failure to maintain the levees protecting the city.

New Orleans Mayor Ray Nagin told CNN the ruling would "open the floodgates" for people in the Lower 9th Ward to seek "proper compensation." He added, "If this is allowed to stand, I think you will see a multitude of lawsuits, the City of New Orleans included."

A Corps of Engineers spokesman said the agency and the Justice Department were reviewing the ruling and would not comment because issues in the case were still subject to litigation.

On Wednesday, U.S. District Judge Stanwood Duval ruled that the corps' shoddy oversight of the channel southeast of New Orleans caused much of the flooding of St. Bernard Parish and the Lower 9th Ward, two of the hardest-hit areas after Katrina.

The decision opens the door to billions of dollars in other claims by more than 100,000 individuals, businesses and even government entities that have pending damage claims against the corps. Duval awarded $720,000 in property damages to four individuals and one business.

In his 156-page ruling, Duval referred to the corps' approach to maintaining the channel as "monumental negligence." He said he was "utterly convinced" that the corps' failure to shore up the channel doomed it "to grow to two to three times its design width."

This "created a more forceful frontal wave attack on the levee" that protected St. Bernard and the Lower 9th Ward, he wrote.