Funny you should say that, because I just checked it out myself today with my body cam recording and mounted to the handlebars of my bike, and after seeing the water level below that of the cycleway and that it was passing under via a couple of large pipes that could be considered a mini-culvert I'm ready to concede that you were correct and that I was wrong! A ford is generally built (or is naturally-occuring) such that the water is flowing across the way all the time, but here it looks like the Champaign Parks District at least attempted to have the cycleway cross above the water level, even though it doesn't take much more flow for it to rise above the level of the cycleway and turn it into a ford. Which explains why when I first checked it out back in 2020 and then again sometime later the water was flowing over the cycleway.

It's too bad OSM doesn't have a way to upload photographs as I could get stills from my video and upload them and along with your photographs we could compare notes. I suppose I could set up a (temporary) web server for the purpose but I'm not sure I'm willing to go that far.

Bottom line: if you want to change it to be temporarily flooded from a ford, go ahead.

I need to get the photographic evidence that supports this, but in a word: no. The reason why is that the stream doesn't go underneath the cycleway, but instead goes parallel to the now-abandoned section of cycleway in the same culvert. The cycleway then crosses the stream via what I mapped as a ford (there's no bridge, it just goes right into the stream, hence why I mapped it as a ford) to continue south as mapped. I mapped the abandoned section of cycleway as such, which is why it doesn't show up in OSM's rendering, but does show up in editors like JOSM. That's also why I mapped the practical altenate route as "Greenbelt Bikeway (detour)."

I documented this in my user diary entry entitlted "Greenbelt Bikeway Edits" on 11 April 2020, which you can find here: @ExpresswayDave/diary/392694

It was a typo. I've removed that tag.

Not for the portion I removed the bike lanes from. I can check again (and get GPS traces) if you want, but I just biked this last weekend and that section doesn't have bike lanes. They only start from State Street eastward.