Over the past few years I have been helping organizing the trail clean up in the Marquette area.
Every year I go in and have a meeting or two with the DNR Rep and find places of interest to them that need attention. We have a set date with them when they will provide a dumpster for us to fill and have it at a set location.
For people that are interested in doing clean ups talk with your local dnr post and let them know what you want to do. It has always worked out well for us up north.
****Also if you are out on the trails and come across dump sites try to mark them on a GPS, by cross trails/roads and take pictures of the site. Take This into the DNR and show them. This provides knowledge of the problem to them and allows them to make a clean up plan for certain areas and hopefully some extra attention to the area to try and prevent further dumping.