Im so sorry that you lost a goose. How sad.
My first thought, since the goose was found in the pool, would be that she was drowned by overzealous breeding on the part of the male.
It is quite possible that he caused the injuries, as well, if it is bare skin with all the feathers pulled, but no puncture marks from teeth.
Were there any injuries that might indicate a predator, such as puncture wounds or rips in the carcass?