In mine closure, artic mines will protect their tailings and waste rock using thermal covers that insulate them from heat, and allow permafrost to form, thus entombing the PAG (Potentially acid generating material - acid drainage presents orange like this too). The frost prevent oxygen (and dissolved oxygen - from water) from interacting with the material, and causing the acid-generating reaction.
With the thawing of natural permafrost, iron that was frozen (as water soluble reduced iron) is released and then oxidized, causing the orange water.
It’s a geochemistry issue.
In mine closure, artic mines will protect their tailings and waste rock using thermal covers that insulate them from heat, and allow permafrost to form, thus entombing the PAG (Potentially acid generating material - acid drainage presents orange like this too). The frost prevent oxygen (and dissolved oxygen - from water) from interacting with the material, and causing the acid-generating reaction.
With the thawing of natural permafrost, iron that was frozen (as water soluble reduced iron) is released and then oxidized, causing the orange water.
So it’s rust.
Rust, or rusty water with battery acid pH