Kazmann says that the Tennessee River and the Missouri River were “the two main culprits” in the 1973 flood. In one high water and another, the big contributors vary around the watershed. An ultimate deluge might possibly involve them all. After Kazmann went home from Old River that time in 1973, he did his potamology indoors for a while, assembling daily figures. In some of the numbers he felt severe vibrations. In his words, “I watched the Ohio like a hawk, because if that had come up, I thought, Katie, bar the door!”

The water was plenty high as it was, and continuously raged through the structure. Nowhere in the Mississippi Valley were velocities greater than in this one place, where the waters made their hydraulic jump, plunging over what Kazmann describes as “concrete falls” into the regime of the Atchafalaya. The structure and its stilling basin had been configured to dissipate energy—but not nearly so much energy. The excess force was attacking the environment of the structure. A large eddy had formed. Unbeknownst to anyone, its swirling power was excavating sediments by the inflow apron of the structure. Even larger holes had formed under the apron itself. Unfortunately, the main force of the Mississippi was crashing against the south side of the inflow channel, producing unplanned turbulence. The control structure had been set up near the outside of a bend of the river, and closer to the Mississippi than many engineers thought wise.

On the outflow side—where the water fell to the level of the Atchafalaya—a hole had developed that was larger and deeper than a football stadium, and with much the same shape. It was hidden, of course, far beneath the chop of wild water. The Corps had long since been compelled to leave all eleven gates wide open, in order to reduce to the greatest extent possible the force that was shaking the structure, and so there was no alternative to aggravating the effects on the bed of the channel. In addition to the structure’s weight, what was holding it in place was a millipede of stilts—steel H-beams that reached down at various angles, as pilings, ninety feet through sands and silts, through clayey peats and organic mucks. There never was a question of anchoring such a fortress in rock. The shallowest rock was seven thousand feet straight down. In three places below the structure, sheet steel went into the substrate like fins; but the integrity of the structure depended essentially on the H-beams, and vehicular traffic continued to cross it en route to San Luis Rey.

Then, as now, LeRoy Dugas was the person whose hand controlled Old River Control—a thought that makes him smile. “We couldn’t afford to close any of the gates,” he remarked to me one day at Old River. “Too much water was passing through the structure. Water picked up riprap off the bottom in front, and rammed it through to the tail bed.” The riprap included derrick stones, and each stone weighed seven tons. On the level of the road deck, the vibrations increased. The operator of a moving crane let the crane move without him and waited for it at the end of the structure. Dugie continued, “You could get on the structure with your automobile and open the door and it would close the door.” The crisis recalled the magnitude of “the ’27 high water,” when Dugie was a baby. Up the valley somewhere, during the ’27 high water, was a railroad bridge with a train sitting on it loaded with coal. The train had been put there because its weight might help keep the bridge in place, but the bridge, vibrating in the floodwater, produced so much friction that the coal in the gondolas caught fire. Soon the bridge, the train, and the glowing coal fell into the water.

One April evening in 1973—at the height of the flood—a fisherman walked onto the structure. There is, after all, order in the universe, and some things take precedence over impending disasters. On the inflow side, facing the Mississippi, the structure was bracketed by a pair of guide walls that reached out like curving arms to bring in the water. Close by the guide wall at the south end was the swirling eddy, which by now had become a whirlpool. There was other motion as well—or so it seemed. The fisherman went to find Dugas, in his command post at the north end of the structure, and told him the guide wall had moved. Dugie told the fisherman he was seeing things. The fisherman nodded affirmatively.

When Dugie himself went to look at the guide wall, he looked at it for the last time. “It was slipping into the river, into the inflow channel.” Slowly it dipped, sank, broke. Its foundations were gone. There was nothing below it but water. Professor Kazmann likes to say that this was when the Corps became “scared green.” Whatever the engineers may have felt, as soon as the water began to recede they set about learning the dimensions of the damage. The structure was obviously undermined, but how much so, and where? What was solid, what was not? What was directly below the gates and the roadway? With a diamond drill, in a central position, they bored the first of many holes in the structure. When they had penetrated to basal levels, they lowered a television camera into the hole. They saw fish.

This was scarcely the first time that an attempt to control the Mississippi had failed. Old River, 1973, was merely the most emblematic place and moment where, in the course of three centuries, failure had occurred. From the beginnings of settlement, failure was the par expectation with respect to the river—a fact generally masked by the powerful fabric of ambition that impelled people to build towns and cities where almost any camper would be loath to pitch a tent.

If you travel by canoe through the river swamps of Louisiana, you may very well grow uneasy as the sun is going down. You look around for a site—a place to sleep, a place to cook. There is no terra firma. Nothing is solider than duckweed, resting on the water like green burlap. Quietly, you slide through the forest, breaking out now and again into acreages of open lake. You study the dusk for some dark cap of uncovered ground. Seeing one at last, you occupy it, limited though it may be. Your tent site may be smaller than your tent, but in this amphibious milieu you have found yourself terrain. You have established yourself in much the same manner that the French established New Orleans. So what does it matter if your leg spends the night in the water.

The water is from the state of New York, the state of Idaho, the province of Alberta, and everywhere below that frame. Far above Old River are places where the floodplain is more than a hundred miles wide. Spaniards in the sixteenth century came upon it at the wrong time, saw an ocean moving south, and may have been discouraged. Where the delta began, at Old River, the water spread out even more—through a palimpsest of bayous and distributary streams in forested paludal basins—but this did not dissuade the French. For military and commercial purposes, they wanted a city in such country. They laid it out in 1718, only months before a great flood. Even as New Orleans was rising, its foundations filled with water. The message in the landscape could not have been more clear: like the aboriginal people, you could fish and forage and move on, but you could not build there—you could not create a city, or even a cluster of modest steadings—without declaring war on nature. You did not have to be Dutch to understand this, or French to ignore it. The people of southern Louisiana have often been compared unfavorably with farmers of the pre-Aswan Nile, who lived on high ground, farmed low ground, and permitted floods to come and go according to the rhythms of nature. There were differences in Louisiana, though. There was no high ground worth mentioning, and planters had to live on their plantations. The waters of the Nile were warm; the Mississippi brought cold northern floods that sometimes stood for months, defeating agriculture for the year. If people were to farm successfully in the rich loams of the natural levees—or anywhere nearby—they could not allow the Mississippi to continue in its natural state. Herbert Kassner, the division’s public-relations director, once remarked to me, “This river used to meander all over its floodplain. People would move their tepees, and that was that. You can’t move Vicksburg.”