State land isn't usually very safe to shoot on. Lack of backstops and all.
I belong to http://www.pawpawconservationclub.com/
It's around a 15 min drive from portage, but it's a decent range and pretty quiet. It's $36 a year IIRC.
You must be sponsored by a member to join though. Come on out on a Tuesday night with a shotgun and shoot some trap with us. It's pretty laid back.