The US Army Corps of Engineers say New Orleans should be able to withstand storms as strong as Hurricane Katrina, when work on new defences is completed next year.
The fifth anniversary of Katrina, which killed 1836 people and left most of the city underwater, is on 29 August. Many neighbourhoods are still abandoned.
Officials say levees are being upgraded and about half of the $US14.3 billion project has been finished.
But some experts say they doubt the new defences will offer sufficient protection.
President Barack Obama is due to visit the city on Sunday to mark the anniversary.
