I have been fishing the Milwaukee River for a few years now and have had success with smallmouth bass. Plastics, like tube baits and wacky worms usually work for me. Good luck exploring the Milwaukee River!
Milwaukee River/Estabrook Park, Milwaukee County
The whole river is fish able because it's shallow enough to go though most of it. If you are pointing towards water that could hold fish such as smallmouth, trout, catfish, suckers, pike, or carp. You can always try local parks that sit right next to the river. Estabrook, Kletch, North Avenue dam(on north avenue st.). There are many spots where many fish would lay in, but choosing the correct presentation is up to you. Otherwise I would suggest to just wade and walk the entire river. cover more ground and find the holes that alot of fish lay in. Hope this helped.