Couldn't be something like maybe someone thought that excited kids and/or horse playing people headed for the water park might accidentally fall into the lake and get hurt? Might explain why they put a fence around "some of the pond". Assuming that's where it was put as that would make some sense.
But that would be too simple and straightforward a reason so that certainly can't be the reason. Got to be something nefarious about it. Maybe they are fencing it off so Barbourville Utility Commission can put in a hydroelectric generator and harness the power of the falling water from the fountains. Or maybe they are secretly building a nuclear reactor and they're going to use the water from that one pond to cool the radioactive cores. Yeah, I bet that's it. They're putting that fence along part of the pond shore so nobody can get into the water and get radiation poisoning.
I don't know why the fence has been put up and don't even know for sure that one has since I haven't been there. However, I sure don't see how putting a fence partly around a pond would suddenly keep people off that whole pond so they could make a pay lake out of it. And I sure don't see why someone would be willing to pay to fish that one pond for a fee when they can fish one of the other ponds for free. And they are all connected you know.
You know, if someone were to actually call the city and ask why the fence is there we might actually find out the real reason. Oh, excuse me. I went crazy there for a minute. Of course the city is just going to lie to use about why they did it. I don't know what I was thinking. Forgive me. I'll just go away now.