gone on the river
The Mississippi downstream of Hastings, or maybe even St. Paul, is not a river.
It kind of looks like a river, if you squint. There are some parts of the classic river ecosystem. But it's not recognizably a river anymore.
It's a canal, on the grand scale of the Panama Canal, but in something like the original channel of something that used to be a river.
It's a progression of lake-terraces, that happen to have a navigation channel forced through them.
In every map along this stretch, there's a huge space between the right and left banks. I'm sure it was always like that. But instead of oxbow lakes, marshes, etc., there are connected lakes, sloughs, almost sort of like alternative rivers. A lake, with islands. Some of those islands trace a line, a course where something that used to be a river used to flow.
The wing dams and closing dams were intended to direct what flow there was into a navigable channel. At this point, with the water levels as they are at this moment, they don't seem to be doing that, or really much of anything. They're far underwater; just a ripple on the surface of the river. They can't direct the flow, because there is no flow to direct.
Instead, the "channel" is something we brute-force into existence. We use fossil fuels to physically remove tons, and tons, and tons of sand. The Army Corps takes it from the bottom of the lake (which we call a river), and deposit it on huge and growing mountains of sand. Sand islands. They're marked on the map as Dredged Material Placement Sites, which sounds very official. They are mountains of sand.
That "channel" has no effect I can ascertain on the movement of the river. It doesn't move the way the real channel does, upstream of the Twin Cities. There is virtually no current. It's not a river, it's a lake with some underwater landcaping.
We have succeeded in making it possible for huge barges to navigate the upper Mississippi from St. Louis to St. Paul. In doing so, we have made it into a fundamentally different thing.