Only $1 billion of the $77 billion the city is seeking from the Army Corps of Engineers is for infrastructure damages it says it suffered because of levee breaches during Hurricane Katrina. The rest is for such things as the city's tarnished image and tourist industry losses.

The city "looked at everything and just kind of piled it on," Mayor Ray Nagin said.

"We got some advice from some attorneys to be aggressive with the number, and we'll see what happens," he said.

New Orleans has joined big business and thousands of homeowners in filing claims seeking compensation from the corps for damages sustained when the levees broke during the 2005 storm, flooding 80 percent of the city.

The claims allege poor design and negligence by the corps led to the failure of flood walls and levees.

The city attorney's office also considered such things as "decreases in the city's image, tourist industry activity and potential business industry, losses in the tax base and generated revenue, and a decrease in the city's overall population," in making the assessment, according to a statement from City Hall.

A spokeswoman for the mayor could not explain how the city quantified losses not tied to infrastructure. A 43-page form filed with the corps, reserving the city's right to sue for $77 billion, also provides little insight. It does not quantify "loss of tax revenue," for example, and supporting documents for city-owned properties, such as a police crime lab and libraries, omit any estimates of property values of flood-related damages, The Times-Picayune newspaper reported Saturday.