Hours after Hurricane Katrina (search) passed, New Orleans was underwater. Some experts say the flooding could have been stopped a quarter-century ago — had environmentalists not interfered.

In 1965, after Hurricane Betsy (search), President Lyndon Johnson authorized the Army Corps of Engineers to build two floodgates at the mouth of Lake Pontchartrain (search). Simulations showed a Category 3 hurricane could raise the water level in the lake by as many as 12 feet, potentially overwhelming the levees and flooding the city — just as Katrina did more than two weeks ago.

The Army spent millions planning the project — until it was stopped by an environmental group called Save Our Wetlands, which filed a lawsuit arguing that the floodgates would damage sensitive marine life.

“If there was some sort of storm structure there, like floodgates, it would have reduced significantly the amount of storm surge into Lake Pontchartrain,” said Prof. Greg Stone of the Louisiana State University Coastal Studies Institute (search).

Today, some environmentalists admit that such a project may be unavoidable, but they also say that restoring natural wetlands is important and would provide a natural barrier against a dangerous storm surge.

“It is not about blame — that’s history. What this is about is saving and protecting lives,” said Valsin Marmillion of American Wetlands. “Any proposal has to be done in concert with saving the wetlands. It is not either/or. It is people figuring out the best science to do this.”

Click in the box near the top of the story to watch a report by FOX News' William La Jeunesse.