Floating huge barges on the majority of the rivers in the U.S. is not natural. It requires massive river altering infrastructure. No where is there more of this infrastructure than on what the U.S. Army Corps of Engineers (Corps) calls the Upper Mississippi River System. This system covers the upper part of the Mississippi River from about Cairo, IL north to Minneapolis, MN and the Illinois River. Below St. Louis, MO all the way to New Orleans (and on the Missouri River) the Corps uses what are called river training structures to narrow and deepen the channel instead of locks and dams.
There are 29 dams on the Upper Mississippi River (UMR) and eight on the Illinois River. All of these dams include at least one lock. Almost all of them were constructed for the purpose of supporting barge navigation. The UMR from St. Louis north and the entire Illinois River is not deep enough to support the oversized barges that are used on these rivers. The dams created artificial slack water pools behind them that maintain an adequate depth for the barges (Figure1). Most of the dams were constructed during the 1930's as work programs during the Great Depression. Several hydroelectric dams already existed so the addition of a lock at each was required to allow barges to move around the dam. Construction of these dams entailed complex construction methods in a river (Figure 2).
In 2007 Congress authorized a new program that would expand navigation on both the UMR and Illinois River. Seven new 1,200-foot locks, estimated to cost over $2 billion, were the primary navigation components of what became known as the UMR Navigation & Ecosystem Sustainability Program (NESP). The navigation expansion was coupled with a major ecosystem restoration component. To read about the locks component of NESP review the 2010 Nicollet Island Coalition report, Big Price - Little Benefit.
For additional information on UMR navigation issues review the River Roils Blog articles and other reports listed below:
Reports on the Inland Waterways System