What kind of mine pit in northeastern Minnesota could make residue that turns water turn bright red?
From the red stain in the water &amp; the rocks in the lower left of the picture it looks like iron ore.

Also, the red stain in the water appears to be a colloidal suspension, consistent with minor erosion of a bank rather than an aqueous stain caused by water reacting with sulfide minerals in the bank.

The Iron Range occurs in north eastern Minnesota.