LOCKS AND DAMS OF THE UPPER MISSISSIPPI RIVER

Upper Mississippi River (UMR) System

      The UMR system is composed of the Upper Mississippi, Illinois, Minnesota, St Croix, Black, and Kaskaskia Rivers. The UMR basin spans parts of Minnesota, Wisconsin, Iowa, Illinois, Missouri, as well as small segments of Indiana and South Dakota. The framework of the Mississippi River was created during the glacial retreat 11,000 years ago. The river included a mix of small channels, islands, and wetlands until the construction of locks and dams; the river has been altered since the early 1800’s, however, to meet various human demands. The UMR system is used for drinking water, irrigation, manufacturing processes, power generation, recreation, and navigation. Navigation infrastructure constructed over last century supports the transport of 100 million+ tons of cargo per year through the UMR system, and approximately 1,300 miles of the UMR system are navigable. In 1986, Congress designated the UMR as a nationally significant ecosystem. The area also provides a large amount of wildlife habitat. 

UMR navigation 

Navigation Infrastructure

      Ten 600-foot long chambers, three 400-foot long chambers, 13 operable dams, 170 dam gates, 8 fixed-crest spillways, and 16 miles of embankments acting as dams. Channel maintenance is done by dredging, using control structures (wing dams, closing dams, bank revetment), snag removal, channel marking, and monitoring of conditions. Boats use this series of locks to step up or down the river between water levels. 

Select History

      - The US Army Corps of Engineers was assigned responsibility of managing the Mississippi River after the UMR surveys and exploration of 1817-1823.

      - The River and Harbor Act of 1930 authorized the construction of a nine foot deep channel between Minneapolis and the mouth of the Illinois River. The act also provided for the construction of locks and dams as a way to guarantee the nine foot channel.