Yes, there is a bathroom you can change in and I think there are showers as well but I'm not positive, so hopefully someone can confirm or correct me if I'm wrong. The entrance is located right behind the pool waterfall .
I don't know about the main pool, but there is a very large, nice, clean bathroom over at the quiet pool for changing. There is no shower there, but I've used it to change after swimming, while waiting for ME back to the airport.