The Atchafalaya Basin exists because of a geological rivalry. For thousands of years through the Holocene epoch, the Mississippi River has periodically tried to abandon its current path to the sea in favor of the shorter, steeper route down the Atchafalaya channel. In the mid-nineteenth century, human intervention accelerated the process: the removal of a massive log jam and extensive dredging permanently connected the two rivers. By the time the Old River Control Structure was completed in 1963, the Mississippi was already diverting an increasing share of its flow westward. Today, by federal law, 30 percent of the combined flow from the Mississippi, Red, and Black rivers is channeled into the Atchafalaya. That regulated torrent carries roughly 25 percent of the Mississippi's total volume, turning the basin into a sediment-rich corridor that feeds one of the only growing deltas on the entire Louisiana coast.

From the air, the Atchafalaya unfolds as an enormous patchwork of dark water, emerald canopy, and silver-gray marsh. About 70 percent of the basin is forested, harboring the largest contiguous block of floodplain forest in the United States and the largest remaining tract of coastal cypress in the country. Bald cypress and tupelo trees rise from the still, tea-colored water on buttressed trunks, their knees breaking the surface like rows of silent sentinels. The basin's thousands of acres of bottomland hardwoods, swamplands, bayous, and backwater lakes shelter the Louisiana black bear, listed as threatened since 1992, along with alligators, migratory birds, and waterfowl. Interstate 10 crosses this wilderness on an 18-mile elevated bridge between Grosse Tete and Henderson, one of the few roads that dare to traverse the basin at all, the rest following the narrow spines of levee tops.

From 1830 to 1953, the community of Bayou Chene flourished at the swamp's heart. The Chitimacha people had lived there long before, establishing villages they called Namu Katsi, the Village of Bones, and Kushuh Namu, the Cottonwood Village. By 1860, 675 residents were farming, logging, hunting, and fishing along the banks of Oak Bayou. Then the Great Mississippi Flood of 1927 rose seven feet above the natural levees, inundating the settlement for weeks. The community limped on through the Great Depression, its residents finding employment building the very levees that would ultimately doom their home. After the basin was designated an official floodway, annual flooding grew relentless. The post office closed in 1952, and the last families scattered to New Iberia, St. Martinville, and Breaux Bridge. Today, Bayou Chene lies beneath at least twelve feet of accumulated silt, a ghost town visible only in memory.

Between 1960 and 1980, oil and gas exploration cut the basin open. Enormous access canals and pipeline channels were dredged through deep swamp, across bayous, and straight through the Atchafalaya River itself. These channels, wide and deep, fundamentally altered the swamp's hydrology. Areas that had been hydraulically isolated were suddenly connected to the sediment-laden river, filling in at rates measured by the USGS at up to several inches per year. Natural bayous choked as their flow was captured by artificial canals. Meanwhile, the levee system designed to funnel floodwaters reduced the percentage of flow reaching the swamp's margins from 30 percent to just 13 percent. Where the water was once black in the 1850s, it turned brown by 1927. Where it was brown in 1927, it has returned to black today, a sign of stagnation and low dissolved oxygen caused by diminished flow, organic buildup, and rising water temperatures.

Along Louisiana's Gulf Coast, salt marshes are degrading at an alarming pace, with the state losing a landmass the size of a football field roughly every hour. But the Atchafalaya's delta is the lone exception, the only location along the entire Louisiana coast where new land is actually forming. Fed by the regulated flow from the Mississippi, sediment builds outward into Atchafalaya Bay and through the Wax Lake Outlet, constructing fresh wetlands at the river's mouth. It is a paradox worthy of the basin itself: the same forces that drowned Bayou Chene and scarred the swamp with oil canals also deliver the raw material for coastal rebirth. The Atchafalaya National Wildlife Refuge, established in 1984, works to protect this fragile balance, nurturing plant communities and habitat for endangered species in a landscape where creation and destruction happen side by side.