The Rock Creek Mine has been a hot topic in Sandpoint for decades. A  permit application for this proposed underground copper and silver mine in northwestern Montana was first filed in the late 1980s by  ASARCO. Ownership of the mining rights changed hands several times, but they are  now held by the Hecla Mining Company of Coeur d’Alene.

An environmental impact statement was completed in 2001. The  project was subsequently challenged in court by the Rock Creek Alliance. The  judge ordered the U.S. Forest Service and mining company to prepare a  supplemental environmental impact statement (SEIS), a draft of which is now available  for public review and comment.

After spending many hours last week  reviewing the draft SEIS and the mine’s potential impacts to North Idaho, here is my take:

  • Under the proposal, Hecla would be authorized to build an evaluation  adit underneath the Cabinet Mountains Wilderness. This horizontal shaft would  be used to collect more information about the ore body and groundwater flows. The  Forest Service also proposes to authorize full-scale mine development and production.  Because so much of the analysis in the SEIS is based on models with a high  level of uncertainty, we feel it is premature to approve full-scale mine  development at this time.
  • Perhaps the greatest uncertainty relates to what impact the  mine would have on the water levels in the high mountain lakes above the mine and  stream flows in Rock Creek and the East Fork Bull River. Analysis of this  issue in the SEIS relies heavily on models, but models are only as useful as  the data entered into them. The evaluation phase of the project would  yield greater certainty about the potential impact of the mine on surface water  quantity and stream flows.
  • If stream flows in Rock Creek and the East Fork Bull River are  substantially reduced, then the Rock Creek Mine would also indirectly affect  bull trout populations inhabiting those streams. The SEIS suggests that substantial  habitat loss is not anticipated, but this stance has not been quantified. Before the  full-scale development of the mine is approved, the models should be updated  using data collected during the evaluation phase.
  • Some of you would probably like to know how a mining company can operate underneath a protected wilderness area. The  patented claims at Rock Creek were filed before the wilderness area was  established. Perhaps the biggest threat to the wilderness is the potential for  a ventilation shaft to be constructed there. The ventilation shaft would  only be constructed if necessary to ventilate the underground workings. The Forest Service and Hecla should evaluate whether other ventilation  options are available that would avoid disturbing the wilderness area above  the mine.
  • The formations that would be mined at Rock Creek appear to  be low in sulfides, so the potential for acid mine drainage also appears  to be low. When exposed during mining operations, sulfides can react to form  sulfuric acid and pollute streams and rivers if left untreated. Again, further  evaluation of the ore body would either confirm or disprove this analysis in the SEIS. The Forest Service would require Hecla to post a bond  to treat any contaminated water flowing from the mine in perpetuity.
  • Heavy metals released from the ore during the milling  process would settle out, mix with the tailings, and  be deposited into the tailing impoundment not far from the Clark Fork River. If  the tailings impoundment ever failed, the tailings and heavy metals  could end up in the river. Heavy metals recovered during the milling  process should be disposed of in a more secure location.
  • The potential for the ground above the mine to subside is  another concern. The Rock Creek Mine would be developed using the "room and  pillar method." Imagine a large room inside a building where pillars are used  to support the ceiling. If those pillars are not big enough, the ceiling either collapses or sags. Subsidence occurred at the Troy Mine just across the  Bull River Valley. Hecla proposes to leave larger pillars at Rock Creek than it did at Troy, but it’s unclear how large the pillars need to be to  prevent subsidence.
  • Perhaps the one environmental benefit of the mine is the  grizzly bear mitigation plan. Hecla would be required to acquire perpetual  conservation easements or to purchase replacement grizzly bear habitat (2,350  acres). Of this, 53 acres would be acquired prior to construction of the evaluation  adit, an additional 1,721 acres prior to mine construction, 10 acres prior to  the air-intake ventilation adit, and 566 acres prior to mine operation. In  addition, habitat improvement would be required on 484 acres, 5.2 miles of  roads would be closed, and a biologist would be funded to undertake  conservation work.

Not discussed in the SEIS is  my longer-term fear about what happens to the mining claims once the mine is  closed. Unless the claims are relinquished at the end of the operation, it’s  possible that another company could reopen the  mine sometime in the future. In other words, who knows what the lifespan of this mine really is?

I will submit comments on behalf of ICL, and I urge you to submit your own comments on Rock Creek Mine.  Thanks for speaking up for Idaho’s clean water and wilderness!