When the New Orleans Sewerage and Water Board developed a plan in 1981 to improve street drainage by dredging the 17th Street canal to increase capacity for Pump Station No.¤6, residents across the city applauded. Increasingly heavy rains were not only flooding streets, but pushing water into homes. Action was needed. It seemed like a no-brainer. Today forensic engineers investigating the levee breach that flooded much of city during Hurricane Katrina aren’t so sure. The search for the cause of the failure keeps returning to that dredging project as the probable starting point for a series of mistakes they believe...