Yes she was in the water - at one point she was holding on to the big duck and it floated into water that was too deep for her and she was calling on Shaun to rescue her.
I don't like Gillian either, and I doubt if I would have been any nicer, but Shaun did go into that task with an attitude towards Gillian and was as awkward as possible to her from the start.
If she'd been there with, say, Sheryl then she would have performed much better as Sheryl knew how to deal with her.