Navigation
Navigation locks allow towboats, barges, and other vessels to transit the dams. Approximately 1350 kilometers (850 mi), from the head of navigation in Coon Rapids, Minnesota down to Cairo, has been made suitable for commercial navigation with a depth of 2.75 meters (9 ft). The agriculture and barge transportation industries have lobbied in the late 20th and early 21st centuries for a multi-billion dollar project to replace the aging lock and dam system. Some environmental groups and advocates of budgetary restraint argue that the project lacks economic justification.
Each lock & dam complex creates a pool upstream of it. There are 29 locks on the Upper Mississippi maintained by the U.S. Army Corps of Engineers—from Upper St. Anthony Falls upstream to Chain of Rocks downstream. The locks provide a collective 123 meters (404 ft) of lift. Note that there is a Lock 5 as well as a Lock 5A. Note also that there is no Lock 23.
Read more about this topic: Upper Mississippi River