Mindful that the suburban West Bank of New Orleans has regained its pre-Hurricane Katrina population and is primed for growth, the Army Corps of Engineers is launching a $1 billion effort to keep the next storm at bay. The new flood protection is already having a potentially dangerous consequence, though: It's encouraging more people to move into another bowl-shaped area that experts consider perhaps the city's most vulnerable flank. While New Orleans' population plummeted by 300,000 after Katrina, residents quickly returned to the west bank of the Mississippi River, many under the mistaken impression that the area was safer. The fact that the West Bank didn't flood was mainly chance, however. Engineers say the area's 250,000 residents...