River Crossing Option #1
In order to stay on the main trail, you will need to cross the river either here (good place, but not my first choice) or a little ways up the trail. At this point, there is a great trail on either side of the river, so either choice will work.
It is important to note that both of these river crossings are considered "low water crossings," so do NOT cross here if high water conditions are in effect.
In other words, if water is running over the top of the concrete crossing paths, then stay off them.