Our models show no changes in water quality in the river. Recent testing of river water also showed no indication of pollution, Murphy said. Yet, depending on the Flambeau River to dilute the mine's effluent was called unacceptable by some environmentalists. It's ridiculous to claim otherwise. Acid can form from metallic mining operations when excavated rock containing sulfur comes into contact with oxygen.
Sulfuric acid can then release metals contained within the rock.
As part of the Flambeau Mine's reclamation, the company crushed the sulfur-laced rock and added limestone to buffer its potential to create acid. The crushed rock was then buried in the bottom of the 220-foot pit and water reflooded the hole. There is some dissolved oxygen in the water but not much. Lynch said ongoing monitoring of the mine's effluent will continue. Should acid and metal levels exceed the levels deemed safe, the company could be instructed to install underground treatment walls that would intercept toxins before they reached the river, or instructed to pump the leachate to the surface and treat it.