Unfortunately, I have found the same to be true around here. We really don't have too many State Parks around, but there is one, and we used to take our dogs there all of the time. Then just a few weeks ago, decided to go (we hadn't been so far this year) and there's a NO DOGS ALLOWED INSIDE PARK sign. HOW RUDE! So, we turned around and went home and as far as I'm concerned won't go back again.
Kala-I'm very glad you enjoyed Lake Murray. I know my profile says I live in Alabama, but I was born in Ardmore and grew up in Lone Grove, OK. We spent EVERY weekend at Lake Murray and when we do get to go back to visit family, that's the only place I want to be. Glad to know they are still so pet friendly, though, b/c next time we'll have Boomer visitin' with us! :D