you need to report this to the cops i would call the DEA or the state police for one you never know a few of the local cops could be in on it
IF you are hunting there or they know you have been there they will come to you and make sure you don't talk or something worst.

I knew a guy who lived in cal. and found some pot on the govt. land that borded his land and he left and the people followed his track back and near beat the h*ll out of him just for being there once

Call the cops that is the only smart thing you can do
this is a link to the dea/ doj website

http://www.usdoj.gov/dea/contactinfo.htm