"If enough water from Lake Pontchartrain topped the levee system along its south shore, the result would be apocalyptic. Vast areas would be submerged for days or weeks until engineers dynamited the levees to let the water escape. Some places on the east bank of Orleans and Jefferson parishes are as low as 10 feet below sea level. Adding a 20-foot storm surge from a Category 4 or 5 storm would mean 30 feet of standing water."

The above was written in 2002 in a newspaper artcile: NOLA