The drought conditions have many people questioning the depth of the river and its reliability for moving cargo up and down the river. For the Upper Mississippi River, the locks and dams as well as other river improvement structures are doing their job of maintaining the 9-foot navigation channel authorized by Congress. On the lower river, however, the unusually dry conditions continue to be a burden threatening closures, reduced loads and major delays for the barge industry and partners.
As early as the 1830s, the federal government began improvements on the river in the interest of navigation. In 1930, after extensive studies by the Corps, Congress authorized the nine-foot navigation channel project on the Upper Mississippi River. This evolved into a stairway of water that maintains a 9-foot deep pool of water (in the navigation channel) behind each dam with the locks allowing vessels to go up or down the stairway. Contrary to some beliefs, the locks and dams were not built for flood control or to eliminate all the low spots caused by shoaling on the river bed (buildup of sediment causing a hazard to navigation).
Shoaling is a natural phenomenon occurring in all moveable bed streams and when it happens in the navigation channel of the Mississippi River dredging is required to keep the channel open.
Throughout the year the Corps conducts hydrographic surveys of the riverbed and prepares a dredging schedule in anticipation of potential trouble areas.
“We use the surveys to lay out the dredge cuts and prepare a contract or use inhouse resources to remove the material,” said Karl Schmitz, dredging coordinator, Operations Division.
The amount of shoaling dictates the number of dredge cuts and the amount of material to be removed to maintain the 9-foot channel.
“The river is constantly changing which presents challenges but we are well equipped to handle them,” said Schmitz.
Even during the drought, dredging operations were normal for the District.
“The locks and dams are doing exactly what they were designed to do – and that is maintaining the 9-foot channel,” says Schmitz.