I find it fascinating just how heavily modified and altered the Mississippi River is north of St. Louis. Starting at Alton, or perhaps we should say at the Chain of Rocks Canal, humans force barges into a series of artificial channels all the way to Minnesota. Of course, the river channel itself it completely altered beyond recognition, as well.
I believe the lock and dam at Winfield is the second to last one, and the day we visited the gates were open, allowing the water to flow through at an even level.
There is a system of dykes and levees that separate off a substantial portion of wetlands and sloughs to the west of the main river channel.