Congress overrode a presidential veto Thursday and approved building miles of levees, closing a navigation channel blamed for flooding during Hurricane Katrina and restoring the badly damaged and eroding Mississippi River delta upon whose survival New Orleans and south Louisiana depends.

The Senate voted 79-14 to override President Bush's veto of the Water Resources Development Act. The legislation is a recurring authorization bill for Army Corps of Engineers projects, but it was last approved by Congress in 2000 and left many critical Louisiana projects in limbo.

Even though the bill passed, money for the projects still must be appropriated and Corps projects have a history of sitting on the shelf for years.

"It's an important milestone, but it doesn't guarantee one nickel of funding," said Mark Davis, director of the Institute on Water Resources Law and Policy at Tulane University.

And the new water bill saddles hundreds of other Corps projects onto an agency that has seen its budget dwindle while its backlog grows, Davis said.

"You add more diners at the table, but there's nothing new coming out of the kitchen," Davis said. "The competition for dollars is going to go up."

In New Orleans, though, the Corps of Engineers has not been hobbled by a lack of funding or held hostage by the delay in passing a Water Resources Development Act, or WRDA. After Katrina, Congress allocated about $7 billion in emergency spending to fix and improve the levees that were destroyed by Katrina and the Corps has moved ahead with pump and levee work.

But the WRDA bill was pivotal to some of the post-Katrina work. For example, it gives the Corps of Engineers the authority to plug the Mississippi River-Gulf Outlet, a channel blamed for causing much of the flooding of St. Bernard Parish and eastern New Orleans during Katrina.

By closing the MRGO, the Corps can move forward with a plan to build a massive floodgate that would protect some of the most historic neighborhoods of New Orleans, including the French Quarter.

The bill also authorizes the Louisiana Coastal Area Ecosystem Restoration project, a $1.9 billion program to build river diversions, restore barrier islands and create marsh by spreading sediment from the Mississippi River into sediment-starved wetlands.

The plan has been in the planning stages for years and it is the blueprint to re-engineering and restoring the Mississippi River delta. The delta has lost an area the size of Delaware, or more than 2,000 square miles, since 1932. The damage was caused by the construction of levees on the Mississippi, natural phenomena and the dredging of canals to access oil and natural gas wells.

The Corps plans to meld coastal restoration projects and levees into a giant coast-wide system to guard against future hurricanes.

Since the 1980s, state and federal agencies have fought the land loss and spent about $1 billion on restoration projects. Despite that work, land continues to disappear.

"Right now we are losing net 17 square miles of wetlands a year, and we have no evidence right now that that rate will change over the next 10 years," said Robert Twilley, the associate vice chancellor of research at Louisiana State University who has worked on restoration plans.

"To get to a no net wetlands loss, you have to have extremely bold implementation."

There are doubts, however, whether the $1.9 billion in funding will be enough. Coastal scientists have said it would cost $14 billion to do the work that's necessary.

The WRDA bill also approves building a 72-mile levee system in Terrebonne and Lafourche parishes at a cost of about $728 million. That levee system, known as the Morganza-to-the-Gulf project, would guard about 200,000 people.

The 16-year project has a number of critics who say the levee system is poorly conceived and would encourage development in areas that are unsafe to live in.

"We cannot afford to build huge, long lines of levees that will provide protection from small, perhaps medium events, but then fail in bigger events," said Steve Ellis of the Taxpayers for Common Sense, a group that has been sharply critical of the Corps. "We need to invest in coastal Louisiana, as far as protecting and restoring the coast, and then we need to very carefully pick where we are going to make our stand."

Robert S. Young, a coastal geologist with Western Carolina University who has studied Louisiana's delta, echoed that sentiment.

He said Louisiana officials dangerously have made the pitch that coastal restoration efforts will protect people living on a coast whose future is uncertain.

"If folks in south Louisiana are not thinking about relocating vulnerable communities while they do these coastal restoration projects, somebody's going to have deaths on their hands," Young said.

Jerome Zeringue, the executive director of the Terrebonne Levee and Conservation District, said the levee system has incorporated lessons learned from Katrina and that it will be an improvement over what's there now.

(Copyright 2007 by The Associated Press. All Rights Reserved.)