I went about 1 1/2 years ago with my parents, we only saw 1/2 the place (it's HUGE) despite being there over 6 hours. I really need to get back and see the rest of it. Hope you went early.
They are an entirely private organisation and can set any rules they want, I don't remember what they are and can't find anything about firearms on their website.
I can't remember if I carried there or not, if I did, I probably CC'd.
Sorry for the late reply, I just got back from Patagonia Lake. Let us know how it went and what their rules are...