Old Man River's Not What He Used to Be

The Mississippi River is resolutely singleminded - its only goal is to reach its destination by the shortest possible route.

Geologists tell us that in pursuit of that goal, the Mississippi carved five distinct channels through Louisiana over the last 7,000 years. Draining nearly 40 percent of the continental United States, the Mississippi picked up huge quantities of sediment in its journey south. As the river slowed in its final approach to the sea, this sediment, mostly clay and organic matter, settled to the river's bed, creating deltas and wetlands.

But if the Mississippi is singleminded, it is also fickle. About every thousand years, it changed course, depriving existing wetlands of lifegiving fresh water and sediment and bestowing them on another portion of the coast. This cycle of creation, abandonment and deterioration produced seven distinct deltoid lobes in Louisiana and added millions of acres to its boundaries. In fact, when the rich and varied resources of the region began attracting European settlers in the early 18th century, Louisiana had more than 4 million acres of coastal wetlands.

However, the unpredictable nature of the river made life hazardous for these early settlers. The spring floods that washed through the wetlands also filled fields and homes, forcing the construction of crude levees. As the population grew, so did the flood control system, navigational dredging and industrial expansion. By the 1940s the combination of these forces had confined the Mississippi to its current channel. The river had been domesticated, but at a price. Hundreds of thousands of acres of wetlands once fed by annual floods were cut off from nutrients and fresh water critical to their survival. They began to die and disappear, while the rich cargo of sediment was carried out into the deep waters of the Gulf.

This loss is unprecedented in the 7,000-year history of the Mississippi. Mankind's attempt at control has produced a radical shift that, if continued, will not only have changed the character of a river but will also alter the face of a continent.