We have a pond where the clay for the bricks of the Tudor farmhouse was dug out, so it's been here a while! Some years it stays full, others it dries up. Some years it has lots of pond weed, or not, lots of floating grass, or not. Good years it teems with Great Crested and Common newts, Great Diving Beetles, dragonflies and damselflies and so on, other years it doesn't. Message here is - they always come back, and we do nothing at all!