Here in Baltimore cuty, there is one official dog park. It's fenced in and has water and the big dog / little dog sides, and it's great -- except that it's not very big. Definitely too small for 15 - 20 big dogs. yet they all come, and they're bound to invade each other's space, and then things go wrong.
Oscar has had to defend himself twice -- both times he was attacked by a misbehaving, aggressive dog. Neither time involved blood, but still scary. I still take Oscar, but only when it's empty or there are only one or two dogs. It's really a shame that it's the only one in the city, but it won't be there long if people don't become more responsible about using it.
oh, but Oscar has soooo much fun there.