Water Quality - promises vs. reality

The IMMine sits astride Wolf Creek and will drain water from the mine into Wolf Creek.  Below we present key points from a recent (2006) scientific study1 of modern era underground and open pit mines, primarily located in the western US (Nevada, California, and Montana).

All mines MUST SAY that they will comply with the Federal Clean Water Act as well as all state and local regulations or they will not be permitted. However, in all cases, inadequate information was provided to demonstrate how the mitigation measures would actually prevent water quality impacts. Therefore, regulators were generally accepting the final water quality predictions on “faith.

The facts from the 2006 scientific study1 of modern era operating hardrock mines (IMM is a hardrock mine) show that actual compliance is rare. (All data is from the same study)

  • 76% of mines polluted groundwater or surface water severely enough to exceed water quality standards.1
  • 73% of mines exceeded surface water quality standards despite predicting that mitigation would result in compliance. The other 4 mines didn’t predict the need for mitigation.
  • 77% of mines that exceeded groundwater quality standards predicted that mitigation would result in compliance. The other 3 mines didn’t predict the need for mitigation.
  • 85% of the mines near surface water with elevated potential for acid drainage or contaminant leaching exceeded water quality standards.
  • 93% of the mines near groundwater with elevated potential for acid drainage or contaminant leaching exceeded water quality standards.
  • Of the sites that did develop acid drainage, 89% predicted that they would not.

The pollutants that exceeded standards were:

  • Toxic heavy metals such as lead, mercury, cadmium, copper, nickel or zinc exceeded standards at 63% of mines.
  • Arsenic and sulfate exceeded standards at 58% of mines.
  • Cyanide exceeded standards at 53% of mines.
(1) “Comparison of Predicted and Actual Water Quality at Hardrock Mines: The reliability of predictions in Environmental Impact Statements” and “Predicting Water Quality at Hardrock Mines: Methods and Models, Uncertainties, and State-of-the-Art” by Ann Maest, PhD and Jim Kuipers, PE. Full report available here.

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