Your pond is so natural and lovely. Just like a pond should look.
Sump? We have a sump pump in our crawlspace. The water table is very high so we sometimes would get several inches of water down there. The sump kicks on under those conditions and pumps the water to the public drain before it can build up downstairs. So I am trying to imagine how you would use a sump. Either for too much rain? Or to capture rain??