In the spring of 1541 Hernando de Soto arrived at the Mississippi River. For much of the next year he and his army waged a losing battle against the natural environment of the floodplain and the numerous peoples who lived there. The following spring, with the river at the level of ahundred-year flood, the Spanish made a sheepish retreat down the valley to the Gulf, and from there to Mexico. The lower Mississippi Valley Soto found was a vast, wet land, a varying combination of water and dirt, from its sandy terraces and natural levees, to its cypress swamps, oxbow lakes, anddeltas, to the big muddy river that runs through it all. Three-and-a-half centuries later, in 1890s Louisiana, cotton planters faced a series of droughts, a new experience for the lower valley, which could always count on a good dousing from the great river that kept it moist through long summers. By the 1890s, however, the valley was drying. Systematicdeforestation, swamp drainage, and levee construction divided much of the lower valley environment into "wet" and "land," water on one side of the levee that prevented from touching the land on the other side. Water frequently returned to the land, sometimes in other guises, as epidemics, insect plagues, loss of soil fertility, microclimate change, most visibly in devastating floods, an eroding coastline, and a sinking delta. Always, the response was to build more barriers between wet and dry. Everyfinger placed in the dike merely caused water to break through somewhere else. In the hours after Hurricane Katrina struck New Orleans, water broke through with a vengeance and reclaimed the land. In cycles dating back thousands of years, long before the first engineered levees, the Louisianacoastline has advanced and receded, the delta has emerged from the Gulf and sunk back into it, the river has changed shape and altered its route to the sea, leaving behind a trail of natural formations. Natural environments are much more than reflections of human history. They need no encouragement to change over time. In the public debate over the causes of the Katrina disaster some blame inadequate levees. Some fault the entire project of flood control for hastening the delta's erosion. Theyforget that that the lower Mississippi Valley has a history of flooding predating engineers and levees. This book tells that history, of the mixing of water and land and people in North America's largest wet land.