Where I'm at, the situation is like dholland says: they are county owned. However, there is "odd arrangements" where there's a committee or foundation or board or something, that administers it. And perhaps something wierd like "leases it from the county for $1 p/year", etc.... And also, there might be fences around them. But go figure, this isn't necessarily because the public can't be there (on the contrary, they WANT the public to be there, and advertise a lot to draw folks for all the activities, haha). The fences are like any stadium or place where entrance fees are collected: so that traffic flows in and out of the collection booth turn-styles, and to minimize people coming in for free, if there were no fence.
I find that even though there are the ominous fences, that there will be times during the week that the gates are opened, in the off-season. Like for when individual buildings are used for AAA meetings, or VFW meeting, or people who go in to tend the animals, etc.... And just because it may be public, and nothing to stop someone from walking around there during the off-season, still keep in mind that there is nothing to stop someone from griping anyhow. (same for parks, school, etc...). So like everywhere, you should pick low traffic times, don't "stick out", don't be in the middle of retrievals when busy-bodies are curiously watching, etc.....