Immediately after Hurricane Katrina pummeled New Orleans last August, President George W. Bush and the U.S. Department of Homeland Security declared that no one could have predicted such devastation. Yet scientists, engineers and Louisiana state politicians had warned for years that a Category 4 or 5 storm crossing the Gulf of Mexico from a certain direction would drown the region. In 1998 computer models at Louisiana State University simulated such a terrible inundation. That same year the state proposed a $14-billion plan to restore the delta's natural wetlands--which, by absorbing water, can help protect inland areas from sea surges. But Congress turned it down.