Sorry for the late reply, don't get on this account much anymore. I was really pleased to see such an in depth and interesting post on one of my pieces.
There do seem to be quite a large number of myths and legends pertaining to women in lakes, either dying there or luring men to their doom, from Ophelia to the Lady of the Lake, its a wonder anyone goes near water!
Whats the name of the poem you mentioned? Is it well known or published? Because I'd love to read it.