Critters and ponds go together. When we have a backyard wildlife habitat, we get the critters that come with it. Let's do the best we can do co-exist. You can just not invite most of these critters. The others we just have to live with.
Turtles will eat your water lilies. So will koi, crawfish, bass, perch or other lake fish. Raccoons and nutria will eat them as well. So will ducks and geese. I don't know about possums or muskrats, but I would not be surprised if they did.
Read all about ponds at Backyard Ponds with the Pondlady