Prof. Child doesn't say much about this. It was the title of the song in the book he got it from. (He "collected" from books, not people).I would not be surprised, but I certainly do not know for a fact, if the well was one of those enchanted or "holy" wells. Since she was clearly a wisewoman or witch (sent the children to learn gramery (sorcery)and conjured them back from death) being the guardian of an enchanted well would be in character.