on castaway creek they are supplied free of charge. just grab one at an entry point.
there aren't any in the wave pool. if you want to use them there, i don't know if you'd be allowed to bring them from other areas of the park, but my guess is No. I'd recommend bringing your own just for the wave pool if you want them.
eta: come to think of it, I didn't notice ANY floats at the wave pool while we were there. Maybe they're not allowed? I'm sure someone here will know the rules.