If It Keeps on Raining, Levee's Going to Break

The loss of New Orleans wasn't just a tragedy. It was a plan.

The evacuation plans were inadequate and then bungled. The rescue was slow, confused, often nonexistent. Yet the most striking fact of the New Orleans catastrophe has received less notice than it deserves: The plan for New Orleans in case of a hit from a very powerful hurricane was to lose the city.

In other words, if a severe hurricane struck, the city's flooding and abandonment was not what would happen if the plan failed. It was the plan.

New Orleans is built between a lake, a river, and the Gulf of Mexico, and it is lower than the surrounding waters. It was kept dry by an extensive system of levees and pumps. That system was itself contributing to the slow subsidence of the city.

The levee system was largely designed in the early 1960s. By the standards of their day, the levees were built conservatively, but within certain constraints. In particular, they were built to withstand a Category 3 hurricane.

Hurricanes come in two jumbo sizes: Category 4 and, most severe but rarest, Category 5. A storm of either magnitude could deliver a surge that would overtop or breach the levees. The city would be flooded, to depths as great as 20 feet. It would become a lake. Much of it would be destroyed, and many people would die.

All of this was well known. Press accounts and public officials have been quite open about it for years. "Evacuation is the only way to protect New Orleanians," reported the Philadelphia Inquirer last year. It quoted Terry C. Tullier, the New Orleans director of emergency preparedness, as saying, "It's only a matter of time." Col. Peter Rowan, the commander of the New Orleans District of the Army Corps of Engineers, told the Inquirer that the city was "at the mercy of chance for the foreseeable future." Media coverage was rife with such warnings.

What could be done? "It's possible to protect New Orleans from a Category 5 hurricane," Al Naomi, a senior project manager with the Corps, told the Inquirer. "To do nothing is tantamount to negligence." In that interview, he estimated that hurricane-proofing the levees and building floodgates at the mouth of Lake Pontchartrain might cost $1 billion and take 20 years. In other interviews, Naomi estimated the cost at $2 billion to $2.5 billion and said the project could be completed in three to five years.

"The point is to eliminate that storm-surge threat with one of these plans," Naomi told Riverside, a Corps of Engineers magazine. "The philosophy of what we do during a hurricane would change. We could spend more time protecting our homes and less time trying to get out of the city in these desperate evacuations."

In 1999, reports the Chicago Tribune, Congress authorized the Army Corps to conduct a $12 million study to determine the cost of protecting New Orleans. But the study was not set to get under way until 2006, and it has so far received funding of only $100,000 to $200,000. "It was not clear why the study has taken so long to begin," the Tribune reported. Meanwhile, Congress and the White House consistently and sharply cut requests for levee-improvement funds.

Katrina came ashore as a Category 4 storm. The levees failed and the city, only partially evacuated, was swamped. "The intensity of this storm simply exceeded the design capacity of this levee," Lt. Gen. Carl Strock, the commander of the Corps of Engineers, told reporters on September 2.

Told so barely, the tale suggests shocking imprudence. But hindsight is 20/20. Remember, the odds of a Category 4 or 5 hurricane hitting New Orleans any given year were small. Strock told reporters, "We figured we had a 200- or 300-year level of protection. That means that an event that we were protecting from might be exceeded every 200 or 300 years. So we had an assurance that, 99.5 percent, this would be OK. We, unfortunately, have had that 0.5 percent activity here."

Remember, too, that reinforcing the levees was a multibillion-dollar project. An ancillary project to restore the protective marshes of the Mississippi Delta, which would have reduced the force of storm surges reaching the city, would cost something like $14 billion over three decades. For that kind of money, there are always competing priorities, some of them urgent.

The question, then, is not whether the failure to improve New Orleans's flood protection was a mistake in hindsight—obviously, it was—but whether it was a reasonable choice in foresight, based on the probable odds and costs as they appeared at the time.

Weighing low-probability, high-cost events is, as it happens, something economists and engineers know a bit about. W. Kip Viscusi, an economist at Harvard Law School and the editor of the Journal of Risk and Uncertainty, points out that the Corps of Engineers was among the first to develop and apply what has become a common cost-benefit template.

Using the more cautious of Strock's figures, assume the odds are that a storm surge would overtop or breach the existing New Orleans levees once every 200 years. This seems, if anything, optimistic, given that Category 4 storms hit the city in 1915 and 1947; that a Category 5 storm (Camille) narrowly missed in 1969; and that the devastating Katrina itself was not a direct hit. Still, assume it. Assume also that officials could reasonably expect the city's inundation, abandonment, and partial destruction to cost, ballpark, $200 billion in direct and indirect economic losses.

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