EVEN WITH THE evacuation unfinished and the structural damage unassessed, it is not too early to start talking about how to rebuild New Orleans and the rest of the Gulf Coast. When residents return to their communities, many will want to rebuild everything exactly as it was. That is understandable. But lessons of the past suggest that this is exactly what should not happen.

In 1969 Hurricane Camille destroyed coastal homes in Mississippi and Louisiana, wiping out much of the area, including Biloxi. But government policy after Camille -- as with government policy after major East Coast hurricanes -- amounted, in the words of one expert, to an "urban development program." Instead of shrinking, coastal development expanded. In truth, local and federal policies, ranging from beach preservation subsidies to zoning laws, have long encouraged building homes along coasts that are unusually susceptible to flooding and wind. Even the National Flood Insurance Program, set up in 1968 to offer government-subsidized flood insurance to susceptible communities in exchange for strict zoning and construction regulations, is at fault. Over the past two decades, the regulatory force of the law has been substantially weakened. All that is left in many places is the subsidy, which thousands of homeowners collect over and over again.

Elsewhere in the country, government programs to acquire property in flood plains have successfully persuaded people to leave them. After the Mississippi River floods of 1993, the town of Valmeyer, Ill., was moved in its entirety, away from the river and onto a surrounding bluff. After Hurricane Floyd in 1999, the city of Kinston, N.C., moved entire neighborhoods out of flood plains and revitalized the city as well. But the political power of wealthy beachfront property owners has prevented such programs from being implemented along the coasts. That must not be allowed to happen again.

The case of New Orleans is even more difficult. New Orleans is not Valmeyer, and cannot be easily moved. Nor is it Biloxi, Miss., where stronger building codes and zoning laws designed to move construction away from the shore could make the city better able to withstand hurricanes. The geography of New Orleans will leave the city forever vulnerable to catastrophic flooding. Yet the city's history and culture make it very much worth saving. As a result, the city, joined by state and federal governments, must begin to face several extraordinarily difficult and delicate issues: Should the lower, most susceptible parts of the city be rebuilt? Should other houses be constructed -- as houses in the city were a century ago -- on stilts? Should the swamps and wetlands around the city be at least partially restored? How should compensation and new housing requirements be handled? Considering the government's murky record of looking after the poor following natural disasters (as the aftermath of Hurricane Camille demonstrated), those most affected by government's decisions must be part of the discussion.

The time to start planning for a rational reconstruction of the Gulf Coast is now. Six months or more down the road, when the rebuilding has already begun, will be too late.