If you are fishing for bass over 6ft deep in rivers, you are wasting your time usually. River water doesn't stratify like a lake does. If you are fishing in the summer, river bends are usually a better bet as they have a higher O2 content and are usually the cooler spots in the river. It also makes natural ambush points for passing baitfish. The deepest I have caught bass in rivers is around 8-10ft, and those fish were suspended in the late summer time when the river level was low and there was very little current and the surface water was becoming stagnant.