I like the tower concept you have going but agree that the pile on the left might become problematic in the long run. I watched closely as Sanjay built rock structures and modified his designs to fit material availability in my area. These structures are made using fiberglass rods and fast set West System epoxy. They really are stable and allow good water movement around them. Something to consider.
You're off to a good start.
Del
My first attempts. Excuse the cloudy water.
I got a little more creative and elaborate on later attempts.
