Ponds are lovely and every time we drive by one I think there should be waterfowl on it. But Domestic ducks just don't live long on them. They don't have the same instincts wild ducks do to get away from predators and most can't fly which makes them sitting targets. Even in water many predators swim so they really don't stand much of a chance trying to live like their wild cousins. If your unhappy with her not being able to get on the pond maybe you should think of finding her a new home where she would be with other ducks? Not on a pond setting but where she would at least have friends. They really thrive much better when in a flock. My waterfowl have never had a pond just large kiddy pools and they are happy as can be. It's because they have their flock and can play in the pools, they don't require much to make them happy.