I have a 1/4 acre wetland with 1/4 acre of watershed. This is the 1st body of water we built 100% ourselves. We used the spoil dirt for a barn pad which is not yet built. We have good clay, cored and packed the berm with a backhoe, and packed the berm in 6" lifts with a sheep's foot roller. It has stayed remarkably full. Once I build the barn and add the roof runoff to the wetland, I am confident it will do very nicely. I really did not expect much, but now understand the value of not cutting corners. We have another pond under construction now and will follow the same recipe for making the dam. This one will have much more watershed (maybe 8 to 1).