The breaches in the levees around New Orleans have been repaired for a year now. But rebuilding the region itself will not gain momentum before the next decade. The levee system as a whole remains inadequate for large storms, and long-term protection for the city and the surrounding delta will not be in place until at least 2011.

To pin down the causes and implications of the levee failures after Hurricane Katrina, the U.S. Army Corps of Engineers has been working with other federal agencies and expert groups, which together form the Interagency Performance Evaluation Task Force (IPET). “We now have high confidence about the lessons learned,” says Lewis E. Link, Jr., a civil and environmental engineer at the University of Maryland and director of IPET’s final report, released in May.