I certainly needed some help with this one - the Tile tool provided a very neat way of splitting the East and West sides of the river bank and the Buffer tool was very handy for getting a continuous intersection
Maybe I did it different than most. I added points to the Map Input tool that I could later use to create a shape that intersected the river at the exact locations, and create a polygon that I could use to split out the river boundary from the state boundaries.
Thanks for this challenge. I had never used any of the spatial tools in Alteryx before so I worked through the solution to understand the process. After reviewing the solution I understand everything that is required for this type of work with one exception.
Under the Select Records tool, how did you know which record to select (6)? Browsing the Poly-Split tool doesn't show me much information visually and the records in the output aren't giving me clarity either.