What Frank said.
A few other rules include...
No puppies under 4 mos or females in heat allowed
All dogs must be supervised at all times by someone over 12.
Anyone under 12 in the park must be accompanied by an adult.
No choke, chain, prong or training collars allowed inside the dog park.
As Frank said, no separate area for small dogs so you'll want to scope out who may already be in there before you go in and keep tabs on the other dogs there if you have a small dog.
If there are small dogs in the park when we bring our border collies in, we try and keep our gang away.
Of course nothing we can do about the small dogs that come chasing ours.
We've had pretty good luck but not all owners are smart/attentive with their dogs and not all dogs love all other dogs.
Know your dog well and stay alert and you should be fine.