In our previous inquiry, we asked about an under water fencing system, which you suggested would be "unsafe".

What if we built a rail road tie wall around that part of the pond area where we don't want the ponds to exit? Imagine a wall from about 6 inches below water level to about 2 feet above water level, then backfilled with dirt on the outside of the railroad ties. After sodding, the ground level on the non-pond side of the railroad ties would be equal to the top of the ties. Then, it would be straight down two feet on the pond side of the ties to water level. Do you think this would contain the swans?