01/28/2009

cbstf / Associated Press

THE PROBLEM: In stretches from Rulo, Neb., to near Hermann, Mo., the Missouri River is losing elevation because the river bottom is washing away. As the river erodes, it can expose navigation hazards, force utilities to lower intakes and migrate up tributaries.

WHO'S AFFECTED: The biggest problem has been for utilities, such as those that use the river to supply drinking water. But the erosion also could eventually threaten the stability of bridges and levees.

THE CAUSE: Why it's happening is unclear. But theories include upstream dams reducing the sediment coming downstream, efforts to channel the river, dredging, floods and other natural processes. The U.S. Army Corps of Engineers is to complete an initial study of the degradation.