As a new hurricane season began Thursday, a widely anticipated report by the U.S. Army Corps of Engineers may shed light on what happened when levees and flood walls were breached by Hurricane Katrina's massive storm surge.

The 6,000-plus page document was expected to include details on alleged engineering and design failures that led to the storm surge overwhelming the city's outer levees and breaking through flood walls within New Orleans, killing more than 1,570 people.

The new report, prepared by the Interagency Performance Evaluation Task Force, is expected to lay out the minutiae of the disaster — flood wall designs, storm surge, storm modeling, levee soil types — in greater depth than the preliminary studies.

"It's a milestone," said Wayne Stroupe, a Corps spokesman.

However, the report is not expected to take a harsh look at the organizational mind-set of the Corps.

Last month, a report by an outside team of engineers said the Corps was dysfunctional and could not be relied upon. That group, led by University of California, Berkeley, recommended setting up an agency to oversee the Corps' projects nationwide.

The Corps is responsible for harbors and navigable waterways. In Louisiana, the agency has an even broader mission of overseeing levee construction, river diversions and coastal preservation projects in the complex Mississippi River delta.

In response to criticism after Katrina, the Corps has made fixing New Orleans' flood protection system a top priority and tried to include new findings from the task force on how to build better levees and flood defenses into its repair work.

Changes have included armoring flood walls so they don't wash away, driving deeper sheet piling to strengthen flood walls and taking into consideration subsidence — the slow sinking of the land.

As the new hurricane season begins, the Corps says it has improved New Orleans' flood protection system above pre-Katrina levels.

A thorough assessment of the region's flood defenses found no "glaring weaknesses," said Col. Richard Wagenaar, the Corps' district chief in New Orleans.

The Atlantic hurricane season runs through Nov. 30.