Although I take Adi to a non-affiliated dog park, you should check out milwaukeedogpa rks.org - It's run by the Residents for Off-leash Milwaukee Parks. Supposedly a group from the East Side came together to form the group and they've had success so far. I am sure if you emailed them, they'd let you pick their brains and point you in the right direction on where to start.
The dog park I take Adi to here is in Mequon, a suburb of Mke and a 10 minute car ride. The first time I went, I was totally amazed. Having been only familiar with South Florida dog parks (which are completely fenced in fields, with agility equipment, fountains, and a smaller fenced off area for small ankle-biters), my jaw dropped when I realized that a real nature park had been devoted to the dogs. Katherine Kerney Dog Park is completely fence-free, with a clearing at the entrance for the dogs to run and play in. It then has a huge trail that goes through the woods, by a stream where all the doggies swim, and many cut-through paths/trails. When it's dry out, the dogs love to take us through the woods off the paths, creating our own. I'll tell you, it was an amazing way to see the fall colors (for the first time - ever! florida=no season but summer!).
Good luck and I hope all of our responses help. Dog parks are great for the pups and for us.
I attached a pic of one of the smaller cut-through paths at our dog park, from when adi was tiny! Summer was in full-bloom.
