What do you want the millpond for? If a wildlife sanctuary geese are not the solution. You could contact your County wildlife trust and ask their advice. What dominates our pond varies from year to year depending on water depth and season - could be water forget-me-not, duckweed, floating grass ... but it's still an important breeding pond for Great Crested Newts, dragonflies, etc. I shoo the wild ducks away in Spring so they don't nest nearby. because they turn it into a dilution of mud.