It's got to be peat mining. I know there are operations up that way, and the color in the aerial view is similar to the color in the ground-level photos with this article:

http://news.minnesota.publicradio.org/features/2004/01/14_robertsont_peat/

I wanna say that the stuff by Nashwauk is the water treatment place.... or it could be the magical place where our power comes from that we're going to be selling to the mine that *might* open when hell freezes over.

Then again, I have no flippin' idea. It's hidden behind some tower mine dump mountains. I've seen city trucks go back there quite a bit, but the road isn't paved (I don't believe). I could ask my redneck neighbors who have them there 4-wheelers that they ride around back there, but they scare me and I value my life. :D