Possible Clues:

• Thelma's pal
• Lake of Alberta
• Charpentier opera
• Poor soul: that is the label for a girl
• Lake in Banff National Park
• Lake ______
• Lady-inspired '84 Human League single?
• See 22 Across
• Madame de, de — de Vilmorin
• Title heroine of a Gustave Charpentier opera