If you do decide to keep it as you have explained then Bobad,s reply is on the money. A packed earthen dam will work just fine, people build houses and roads with the same method, the Great wall of China. Two or three day laborers and a couple of short, stout pieces of wood and in a day or two you are on your way. I like your idea of fish to feed the birds, most of us have the same thing happening but we would rather it didn't.
