The CuMo Mining Exploration Project

If the Idaho Copper Corporation (ICC) has its way the headwaters of the Boise River will be transformed by the largest open-pit copper mines in the Americas if not the globe. The CuMo mine has the potential to become one of the most controversial mining projects in the United States and places the drinking water, recreation resources, and habitat that the Boise River provides at stake.

The CuMo project is proposed for a forested ridge on the south side of Grimes Creek upstream of Pioneerville and Idaho City, only 35 miles from Boise. While the project is in the Boise River watershed, it's just a stone's throw from Garden Valley and the South Fork of the Payette River.

The project is still in its relatively early exploration phase and is calling for four years of drilling followed by two years of final reclamation. To accomplish their exploration goals, ICC is proposing the construction of 8.9 miles of new temporary roads, constructing 122 drill pads, and ultimately drilling up to 250 exploratory drill holes.

It was identified in a previous Preliminary Economic Analysis that part of the ultimate goal of this project is to construct a 3,500-foot deep open pit in order to mine the metals. The analysis additionally outlines the potential for a massive tailings facility (around 800’ high and 10,000 feet wide) to be built upstream of Pioneerville, Centerville, and New Centerville if the current mining plans stay as is and are approved after exploratory drilling.

With the site being just 15 miles from Idaho City and upstream of one of Boise’s primary drinking water supplies, it is critical that the public be made aware of the proposal and how it could impact water quality as well as wildlife and recreation within the area.

In May 2011, after receiving more than 500 comments from concerned citizens, the U.S. Forest Service released the Final Environmental Assessment for the CuMo Exploration Project and issued a Finding of No Significant Impact.

The decision permitted the Canadian mining company, then Mosquito Gold Company, to conduct a five-year mineral exploration project, including the construction of up to 10.2 miles of new temporary roads and four new stream crossings.

In July 2011, Idaho Rivers United, along with the Idaho Conservation League and Golden Eagle Audubon Society, filed a complaint challenging the Forest Service's approval of the CuMo Exploration Project. Advocates for the West represented our claim that the Forest Service had not evaluated what impact the road construction and the extensive drilling activities will have on groundwater and on sensitive species in the project area, including wolverines, northern goshawks, and Great grey owls.

On August 29, 2012, U.S. District Judge Edward J. Lodge found that the U.S. Forest Service’s actions were “arbitrary and capricious” when it approved the CuMo Exploration Project without examining potential effects to groundwater. He remanded the agency’s environmental document for further study and consideration and halted all exploration activities that were previously permitted under the plan.

Following this case, the Forest Service performed additional analysis and baseline studies to address the deficiencies in groundwater impacts and published a Supplemental Environmental Assessment in 2015. Following this release, IRU joined ICL and Golden Eagle Audubon Society to challenge the assessment and once again the courts found that the assessment was lacking. This time, it was determined that the groundwater analysis had been improved, however, the analysis was deficient when examining the impacts to Sacajawea’s Bitterroot.

In 2018 the Forest Service launched their third round of analysis for the CuMo project specifically to address the deficiencies outlined in our most recent challenge and to address baseline condition changes resulting from the Grimes Creek and Pioneer fires that impacted the area between rounds of study.

These studies were never completed and the project remained in question until this most recent proposal was submitted. Despite yet another change in ownership and a pivot to focus on copper rather than molybdenum deposits, the submitted plan and threat to the Boise River watershed remain unchanged.