The surface of a river will tell you all about what is underneath it. Stripers are highly structure oriented. Structures you should look for are current breaks and seams. A current break is any aspect of the river that changes the flow of the current. Current breaks include the traditional rocks, downed timber, and bridge pilings, but they also include chutes, where the current is narrowed and sped up, and holes, where the current eases and an eddy is formed.
Current breaks create seams, the primary structure a striper relates to.
Another portion will be fish that followed your lure from the seam to the strike point. There are a couple of things to remember when analyzing the surface of a river. First, seams and current breaks can be subtle, but no less effective, so pay attention. A seam can be an area where slightly choppy water turns flat. Second, the deeper the water, the further downstream evidence of an obstruction will appear on the surface.