In 1718, French colonist Jean Baptiste Le Moyne de Bienville ignored his engineers' warnings about the hazards of flooding and mapped a settlement in a pinch of swampland between the mouth of the Mississippi River, the Gulf of Mexico and a massive lake to the north.
Ever since, the water has sustained New Orleans and perpetually threatened it. Somehow, until this week, the mystique of the water had always washed away the foreboding of disaster, as if carrying the city's worries downstream. That was true even early Tuesday morning, when Hurricane Katrina's last-minute veer to the east convinced many residents they had once again eluded the Fates.
But when the rainfall brought by Katrina breached levees and overwhelmed the city's pumping stations, the catastrophic consequences of Bienville's miscalculation could no longer be ignored.
New Orleans, a city that has struggled to keep its head above water, physically and economically, is now a city submerged.
City officials estimated that 80% of the town was under standing water Tuesday, with some areas beneath as much as 20 feet. Water at times coursed through the French Quarter, one of the highest points in a city that is largely below sea level.
In broad swaths, the flooding submerged low-lying neighborhoods up to the rooftops and left one of America's most enchanting cities a sodden ruin.
For locals, it is a cruel paradox. The water that has given New Orleans its very life -- its commerce, its cuisine, even the meandering flow of its daily pace -- has now rendered their beloved city almost unrecognizable.
The charming quirks of its geography -- like the practice of entombing the dead aboveground because high water tables make burial a short-term proposition -- may no longer seem so charming. The water, cherished by Bienville for its potential to open the region to commerce, has now all but strangled access. Bridges and causeways are shredded, and city streets are buried in debris.
"The river gives and the river basically takes away," said novelist Richard Ford, who lived in New Orleans until last year. "There really isn't a vocabulary that I have access to that describes this. And as always, it's the least able to recover from this disaster who will suffer most intensely."
Ford, like other New Orleans devotees, said it was a facet of the city's famed insularity that residents managed to avert their attention from impending disaster.
"If you live in New Orleans," he said, "you've decided that whatever it is about that city that you like is more important than whatever anxiety you feel."
Curtis Wilkie, an author and journalism professor who has lived in the French Quarter for 12 years, said he had previously found a sense of comfort in the water around him.
"It's always been part of the attraction of New Orleans -- the river and the lake and the Gulf," he said. "Whatever peril there was, it was outweighed by the charm of the city. But there's no city in America that has quite the relationship with water that we do. And everybody knew that this was a potential disaster."
Indeed, centuries after Bienville, geographers and engineers have been warning with increasing alarm that a storm like Katrina could devastate a region of 1.3 million people, leaving tens of thousands dead or homeless.
The water, after all, is everywhere. Lake Pontchartrain, just north of the city center, is 300 square miles and is crossed by a 24-mile causeway, the longest over-water bridge in the world. The Mississippi River pushes 300,000 cubic feet of water past the city every second, at depths that average 90 feet.
There is virtually no major route into the city that does not traverse vast expanses of brackish blue. The Port of New Orleans is one of the country's busiest, with more than 6,000 vessels passing the city annually.
Offshore oil is another economic stimulant, as are fishing and aquaculture. Much of the city's $5-billion convention and tourism industry is tied to the riverfront, with its Riverwalk Marketplace, aquarium and dockside paddle wheelers.
A Category 4 or Category 5 storm, geologists long theorized, would exploit the eroding Louisiana coastline and the gradual settling of the city's earthen foundation, and compromise the more than 500 miles of levees and floodwalls holding back the river and lake. Armed with computer models, they predicted that hundreds of years of engineering would make little difference.
Experts have recommended replenishing the more than 1 million acres of coastal marshland that have vanished into the sea since 1930, largely the result of human intrusion. A study panel concluded the cost could top $14 billion.
Other proposals have included rebuilding barrier islands, erecting more levees and restricting the flow of water into channels and canals. A Louisiana State University professor even proposed building a two-story wall with floodgates to secure the southern part of the city, saying the walled zone could serve as a municipal refuge in a killer storm.