Thursday's admission is a huge about-face for the Army Corps of Engineers. Their report says: "The hurricane protection system in New Orleans and Southeast Louisiana was a system in name only."
The more-than-6,000-page report went on to say the flood defense that engineers built over decades "was compromised by the incompleteness of the system, the inconsistency in levels of protection, and the lack of redundancy."
"This is the first time the Corps has had to stand up and say we had a catastrophic failure of one of our projects," says chief engineer Lt. Gen. Carl Strock.
The $19.7 million review pointed out details of engineering and design failures that led to Katrina's storm surge overwhelming the city's levees and floodwalls.
According to the report, the walls failed when the water pushed the walls enough to create a crack between them and the levee soils, allowing the water to seep below the walls and push them aside.
To independent investigators the report is an epiphany of sorts for Corps leaders that they finally get that the Corps was part of the problem.
"The acknowledgment of human factors and organizational issues by the Corps of Engineers is hugely important," says Professor Ray Seed, a levee expert at the University of California, Berkeley.
But for New Orleans residents at the start of a hurricane season the study only adds to concern. After all, the Corps just spent nine months and more than $750 million restoring the very system it now criticizes.
"Should we check and recheck everything the Corps does in the future?" asks Sandy Rosenthal, the founder of Levees.org, a grass-roots group formed to hold the the federal government accountable for its failures. "Absolutely!"
The Corps says it has learned from its mistakes — pointing to three giant floodgates placed on Lake Pontchartrain to prevent storm surge from hitting the city again. Those and other improvements, the Corps says, will dramatically reduce risk.
With the memories of last year still haunting so many, all the people of New Orleans can do now is hope the Corps is right.