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October 5, 2005: Features
The
control of nature
By John McPhee ’53
In The Control of Nature, published in 1989, John McPhee ’53 explored the human struggle against nature – including an effort to manage the flow of the Mississippi River. “The Mississippi River, with its sand and silt, has created most of Louisiana, and it could not have done so by remaining in one channel,” McPhee wrote in a sketch called “Atchafalaya,” named for the Atchafalaya River. Since the middle of the 19th century, the Atchafalaya had widened and deepened as it drew more and more water from the Mississippi, threatening to capture the master stream, as other distributaries had captured it before. “For the Mississippi to make such a change was completely natural,” McPhee wrote, “but in the interval since the last shift Europeans had settled beside the river, a nation had developed, and the nation could not afford nature.” Thus began efforts by the U.S. Army Corps of Engineers to prevent the Mississippi’s capture.
Since Hurricane Katrina, many readers have been returning to McPhee’s book. This excerpt, reprinted with permission of Farrar, Straus and Giroux, refers to several individuals who require identification: Oliver Houck, professor at Tulane University; Raphael G. Kazmann, professor of civil engineering at Louisiana State University; Fred Chatry, chief engineer of the New Orleans District of the U.S. Army Corps of Engineers; and Maj. Gen. Thomas Sands, commandant of the Corps’ Vicksburg Division. The excerpt begins after an explanation that without human intervention southern Louisiana would be continuously covered with fresh sediments and water. Until about 1900, sediments transported by the river combined to fill in land even while many spots sank. But levees soon isolated the river and prevented its overlows from depositing new sediments. — Eds.
What was a net gain before 1900 has by now been a net loss for nearly a hundred years, and the Louisiana we have known — from Old River and the Acadian world to Bayou Baptiste Collette — is sinking. Sediments are being kept within the mainline levees and shot into the Gulf at the rate of 356,000 tons a day — shot over the shelf like peas through a peashooter, and lost to the abyssal plain. As waters rise ever higher between levees, the ground behind the levees subsides, with the result that the Mississippi delta plain has become an exaggerated Venice, 200 miles wide — its rivers, its bayous, its artificial canals a trelliswork of water among subsiding lands.
The medians of interstates are water. St. Bernard Parish, which includes suburbs of New Orleans and is larger than the state of Delaware, is 2 percent terra firma, 18 percent wetland, and 80 percent water. A ring levee may surround a whole parish. A ring levee may surround 55 square miles of soybeans. Every square foot within a ring levee forces water upward somewhere else.
An Alexander Calder might revel in these motions — interdependent, interconnected, related to the flow at Old River. Calder would have understood Old River Control: the place where the work is attached to the ceiling, and below which everything — New Orleans, Morgan City, the river swamp of the Atchafalaya — dangles and swings.
Something like half of New Orleans is now below sea level — as much as 15 feet. New Orleans, surrounded by levees, is emplaced between Lake Pontchartrain and the Mississippi like a broad shallow bowl. Nowhere is New Orleans higher than the river’s natural bank. Underprivileged people live in the lower elevations, and always have. The rich — by the river — occupy the highest ground. In New Orleans, income and elevation can be correlated on a literally sliding scale: the Garden District on the highest level, Stanley Kowalski in the swamp. The Garden District and its environs are locally known as uptown.
Torrential rains fall on New Orleans — enough to cause flash floods inside the municipal walls. The water has nowhere to go. Left on its own, it would form a lake, rising inexorably from one level of the economy to the next. So it has to be pumped out. Every drop of rain that falls on New Orleans evaporates or is pumped out. Its removal lowers the water table and accelerates the city’s subsidence. Where marshes have been drained to create tracts for new housing, ground will shrink, too. People buy landfill to keep up with the Joneses. In the words of Bob Fairless, of the New Orleans District engineers, “It’s almost an annual spring ritual to get a load of dirt and fill in the low spots on your lawn.” A child jumping up and down on such a lawn can cause the earth to move under another child, on the far side of the lawn.
Many houses are built on slabs that firmly rest on pilings. As the turf around a house gradually subsides, the slab seems to rise. Where the driveway was once flush with the floor of the carport, a bump appears. The front walk sags like a hammock. The sidewalk sags. The bump up to the carport, growing, becomes high enough to knock the front wheels out of alignment. Sakrete appears, like putty beside a windowpane, to ease the bump. The property sinks another foot. The house stays where it is, on its slab and pilings. A ramp is built to get the car into the carport. The ramp rises three feet. But the yard, before long, has subsided four. The carport becomes a porch, with hanging plants and steep wooden steps. A carport that is not firmly anchored may dangle from the side of a house like a third of a drop-leaf table. Under the house, daylight appears. You can see under the slab and out the other side. More landfill or more concrete is packed around the edges to hide the ugly scene. A gas main, broken by the settling earth, leaks below the slab. The sealed cavity fills with gas. The house blows sky high.
...
The river goes through New Orleans like an elevated highway. Jackson Square, in the French Quarter, is on high ground with respect to the rest of New Orleans, but even from the benches of Jackson Square one looks up across the levee at the hulls of passing ships. Their keels are higher than the Astro Turf in the Superdome, and if somehow the ships could turn and move at river level into the city and into the stadium they would hover above the playing field like blimps.
In the early 1980s, the U.S. Army Corps of Engineers built a new large district headquarters in New Orleans. It is a tetragon, several stories high, with expanses of sheet glass, and it is right beside the river. Its foundation was dug in the mainline levee. That, to a fare-thee-well, is putting your money where your mouth is.
Among the 500 miles of levee deficiencies now calling for attention along the Mississippi River, the most serious happen to be in New Orleans. Among other factors, the freeboard — the amount of levee that reaches above flood levels — has to be higher in New Orleans to combat the waves of ships. Elsewhere, the deficiencies are averaging between one and two feet with respect to the computed high-water flow line, which goes on rising as runoffs continue to speed up and waters are increasingly confined. Not only is the water higher. The levees tend to sink as well. They press down on the mucks beneath them and squirt materials out to the sides. Their crowns have to be built up. “You put five feet on and three feet sink,” a Corps engineer remarked to me one day. This is especially true of the levees that frame the Atchafalaya swamp, so the Corps has given up trying to fight the subsidence there with earth movers alone, and has built concrete floodwalls along the tops of the levees, causing the largest river swamp in North America to appear to be the world’s largest prison. It keeps in not only water, of course, but silt. Gradually, the swamp elevations are building up. The people of Acadiana say that the swamp would be the safest place in which to seek refuge in a major flood, because the swamp is higher than the land outside the levees.
As sediments slide down the continental slope and the river is prevented from building a proper lobe — as the delta plain subsides and is not replenished — erosion eats into the coastal marshes, and quantities of Louisiana steadily disappear. The net loss is over 50 square miles a year. In the middle of the 19th century, a fort was built about 1,000 feet from a saltwater bay east of New Orleans. The fort is now collapsing into the bay. In a hundred years, Louisiana as a whole has decreased by a million acres. Plaquemines Parish is coming to pieces like old rotted cloth. A hundred years hence, there will in all likelihood be no Plaquemines Parish, no Terrebonne Parish. Such losses are being accelerated by access canals to the sites of oil and gas wells. After the canals are dredged, their width increases on its own, and they erode the region from the inside. A typical 300-foot oil-and-gas canal will be 600 feet wide in five years. There are in Louisiana 10,000 miles of canals. In the 1950s, after Louisiana had been made nervous by the St. Lawrence Seaway, the Corps of Engineers built the Mississippi River-Gulf Outlet, a shipping canal that saves 40 miles by traversing marsh country straight from New Orleans to the Gulf. The canal is known as Mr. Go, and shipping has largely ignored it. Mr. Go, having eroded laterally for 25 years, is as much as three times its original width. It has devastated 24,000 acres of wetlands, replacing them with open water. A mile of marsh will reduce a coastal-storm-surge wave by about one inch. Where 50 miles of marsh are gone, 50 inches of additional water will inevitably surge. The Corps has been obliged to deal with this fact by completing the ring of levees around New Orleans, thus creating New Avignon, a walled medieval city accessed by an interstate that jumps over the walls.
“The coast is sinking out of sight,” Oliver Houck has said. “We’ve reversed Mother Nature.” Hurricanes greatly advance the coastal erosion process, tearing up landscape made weak by the confinement of the river. The threat of destruction from the south is even greater than the threat from the north.
I went to see Sherwood Gagliano one day — an independent coastal geologist and regional planner who lives in Baton Rouge. “We must recognize that natural processes cannot be restored,” he told me. “We can’t put it back the way it was. The best we can do is try to get it back in balance, try to treat early symptoms. It’s like treating cancer. You get in early, you may do something.” Gagliano has urged that water be diverted to compensate for the nutrient starvation and sediment deprivation caused by the levees. In other words, open holes in the riverbank and allow water and sediment to build small deltas into disappearing parishes. “If we don’t do these things, we’re going to end up with a skeletal framework with levees around it — a set of peninsulas to the Gulf,” he said. “We will lose virtually all of our wetlands. The cost of maintaining protected areas will be very high. There will be no buffer between them and the coast.”
Professor Kazmann, of LSU, seemed less hopeful. He said, “Attempts to save the coast are pretty much spitting in the ocean.”
The Corps is not about to give up the battle, or so much as imagine
impending defeat. “Deltas wax and wane,” remarks Fred Chatry,
in the pilothouse of the Mississippi. “You have to be continuously
adjusting the system in consonance with changes that occur.” Southern
Louisiana may be a house of cards, but, as General Sands suggested, virtually
no one would be living in it were it not for the Corps. There is no going
back, as Gagliano says — not without going away. And there will
be no retreat without a struggle. The Army engineers did not pick this
fight. When it started, they were still in France. The guide levees, ring
levees, spillways, and floodways that dangle and swing from Old River
are here because people, against odds, willed them to be here. Or, as
the historian Albert Cowdrey expresses it in the introduction to “Land’s
End,” the Corps’ official narrative of its efforts in southern
Louisiana, “Society required artifice to survive in a region where
nature might reasonably have asked a few more eons to finish a work of
creation that was incomplete.” 
