Here is the pond we built at my parents' old house. I miss it.
Dad dug it out by hand....poor guy. It was almost 3' deep at the deepest part (under the waterfall). It had a ledge around it so we could sit plants on it. We also had potted plants sunk it at each end. The lillies would take over...we'd have to keep them in check. We put fantail goldfish in, and within a few years they had gotten rather large and multiplied like crazy. One day a heron discovered the fish and cleaned almost all of them out. We had to put netting over it after that. It was pretty low maintenance...except I'd have to fix the rocks that had fallen in, or pull out plants if they got out of control. We would unplug the waterfall in the winter and just let the pond freeze over. We completely cleaned it out once or twice, but we didn't have to do much other than that.