From my experience, they seem to try and stay out of current as much as they can. Not knowing the area I can only take guesses on the amount of sunlight per day, rain run off, water clarity and so on.
I would try and concentrate in the main river but close to where a creek/river/ spring flows into it. Fish might be hiding and waiting for a meal to come out of those creeks. Weed beds would also be a good bet. Try the edges first and work your way inside the weeds.
I am not seeing big numbers of fish in one particular area (in a school) but they hang out in the same structure. You might catch 2 fish per brush pile, you might catch 10. Same with the edge of a weed bed. Two in one spot, one in another.
Move, move, move, don't wait for the fish to come to you. You learn more this way. Lastly... keep a log book. You can look back year after year and be surprised that the fish react the same based on moon, weather, temp and so on.
You'll find em.