Before Hurricane Katrina breached a levee on the New Orleans Industrial Canal, the Army Corps of Engineers had already launched a $748 million construction project at that very location. But the project had nothing to do with flood control. The Corps was building a huge new lock for the canal, an effort to accommodate steadily increasing barge traffic. Except that barge traffic on the canal has been steadily decreasing. In Katrina's wake, Louisiana politicians and other critics have complained about paltry funding for the Army Corps in general and Louisiana projects in particular. But over the five years of President...