[Elsa's never a fan of strange, magical thing happening in this place - it almost always marks the beginning of trouble. She's spent a good while trying not to go in the direction the water wants her to despite its enthusiastic encouragement, but after a while, even she cant deny it... seems pretty harmless. Happy, even.
Tl;dr, feel free to notice one older sister standing just out of reach of the stream, smiling a little at its antics.]