Feel free to comment in the discusson section.  Although I’m no scientific expert here are some possible theories that come to mind.  Is there some sort of whirlpool effect happening below the surface?  Even though it is a river it isn’t a super fast flowing river.  Or is there some type of paranormal or gravitational effect happening.  I’m personally stumped on this one.  Without intervention below the surface or some sort of construction shaping this thing, it remains truly confusing.  Does this river sit on some sort of latitudinal and longitudinal point of significance?

The narrator states it is west of a bridge so exploring any kind of dam construction and the like in the area may be of benefit.