Safeguarding the Boise River watershed from CuMo mining exploration

23rd of Oct 2023

Advocates for the West and our partners are speaking out against a mining exploration project proposal in the headwaters of the Boise River, posing major threats to water quality, fish, and wildlife. The groups succeeded in blocking variations of the project twice before.

Idaho Copper is seeking approval from the U.S. Forest Service to construct up to eight miles of new roads and clear 122 drill pads on National Forest lands near Grimes Creek. Through this project, called the CuMo Mine Exploration Project, Idaho Copper hopes to find sufficient copper and molybdenum to excavate one of the largest open-pit accessible molybdenum mines in the world—all within the Boise River watershed.

“Don’t be fooled by the mining company’s new name and branding,” warned Bryan Hurlbutt, Staff Attorney at Advocates for the West. “This is the same troubled project that has failed to get off the ground for over a decade now, and it still poses unacceptable risks to our public lands and the Boise River watershed.” 

“Just the exploration alone poses threats to our water quality, recreation, traffic, public safety, and wildlife—and it is a dangerous stepping stone to massive amounts of pollution in the Boise River headwaters from an open pit mine,” said John Robison, Public Lands Director with the Idaho Conservation League.

“Despite the fact that this project is still in its exploration phase, it warrants incredible concern when you look at published documents from the company. If all goes to plan, this project will result in one of the largest open-pit mines in the Americas that has the potential to jeopardize one of Boise’s primary sources of drinking water,” said Nick Kunath, Conservation Program Manager at Idaho Rivers United.

“The project site includes some of the best forest habitat remaining in the Boise Basin for an array of wildlife, including sensitive species like great grey owl, American goshawk, and wolverine,” said Cynthia Wallesz, Executive Director of the Golden Eagle Audubon Society. “The exploration area also hosts a rare flower found only in the mountains of central Idaho, Sacajawea’s bitterroot.”

At Issue

The Boise River is the lifeblood of the Treasure Valley. The exploration site is upstream of half of Idaho’s population, and the Boise River watershed provides approximately 30 percent of Boise’s drinking water supply and irrigates over 300,000 acres of farmland. This proposal places the entire watershed—and all who rely on it—at unacceptable risk.


This isn’t the first time a variation of this project has been proposed, or that conservation groups have spoken out and taken action. A federal court struck down the project in 2012 because the Forest Service failed to adequately assess the risks that extensive underground drilling could contaminate groundwater. The court struck it down again in 2016 because of the project’s threats to Sacajawea’s bitterroot.

Take Action

Because the CuMo Mine Exploration Project is located mostly on public National Forest lands, Idaho Copper needs approval from the Forest Service, which is currently taking public comments on issues to consider in its analysis. The public is encouraged to speak up about their personal thoughts and concerns over the project and how it might affect their use of public lands. Public comments should be submitted to the Forest Service by Nov. 2 to ensure they are included in the agency’s analysis of the project. The Forest Service is expected to release a draft Environmental Assessment for additional public comment this winter.