Hopatcong State Park Fee

I was going to visit Hopatcong State Park this evening, but I noticed there is an entrance fee. I'm curious if anyone has more details of how this works.

http://www.state.nj.us/dep/parksandfo.../hopatcong.html

It seems like it's like the beach where someone is there during the day to watch, but at night you may be able to just visit? I just wanted to take some photos of the lake and go for a walk. I'm not sure if you have to pay the fee even if you show up at 7 pm for an hour before the sunsets.