Shepard is from Redcliffe. She knows this area and the lakes all too well. Even if she had been avoiding this place since the Blight, she still knows it like muscle memory.

She's scouting when he sees the dark haired woman out on the ice. This place has some areas with ice that seems like it goes right out of it's way to trick you into thinking it's safe and this caravan is pretty close to an area notorious for it.

"Hey!" Shepard calls, careful to be loud enough to catch attention, but not too loud to cause trouble, and then slides down the side of the hill she had been on to catch up to the woman.