Water Quality Study Underscores Dangers of Cyanide Gold Mining in Centennial Mountains
Waves of early summer rain lashed the Idaho side of the Centennial Range. Despite the drizzle, student researchers from Brigham Young University-Idaho spilled out of their van laughing in shorts and T-shirts, carrying collection bottles and notepads. One of the braids of Camas Creek running beneath the road just outside Kilgore was high with the last of a melting snowpack, the burbling water jostling streamside willow branches.
As part of a chemistry department internship, with support from the Greater Yellowstone Coalition, the student researchers were measuring water quality in the Camas Creek watershed. This headwaters system is downstream of the Kilgore Gold Exploration Project, a drilling operation led by a financially unstable foreign mining company that could lead to an open-pit, heap-leach, cyanide gold mine.
The students measured alkalinity, or how well a stream can buffer changes in pH, among other water quality indicators. The students found low alkalinity levels, meaning Camas Creek, which fish and farmers alike depend on, is not equipped to handle decreases in pH from acid mine drainage. This form of pollution is common in historic open-pit mines in wet areas such as Kilgore.
BYU-I students test water in a stream near Kilgore. Photos GYC/Tom Hallberg
Nestled in eastern Idaho’s Centennial Mountains, Kilgore is a small agricultural town where ranchers graze cattle, generations of Idahoans come to recreate, and elk, grizzly bears, and wolverines reside. The cold clear streams that flow here provide habitat for Yellowstone cutthroat trout, water for local farms and ranches, and recharge the Eastern Snake Plain Aquifer, the primary source of clean drinking water for 300,000 people.
“Kilgore's historic ranching practices depend on access to the streams that would likely be disrupted by a future mine,” according to Ryan Sargeant, the chemistry professor at BYU-I who led the study. “The entire watershed is also uniquely susceptible to the types of background pollution that this type of mine would likely generate.”
If Excellon Resources’ exploration finds enough gold in Kilgore, it would likely construct an open-pit, heap-leach, cyanide mine.
From the deep South to Colorado and the rest of the Intermountain West, mining companies have left communities to pay millions to treat acid mine drainage pollution. The results of this study show that Kilgore and Clark County would be at risk of doing the same if Excellon builds a gold mine there.
Cyanide is a highly toxic chemical that can poison groundwater, kill wildlife, and cause lasting damage to ecosystems. Once it contaminates groundwater, it’s incredibly difficult to clean up and the impacts can be felt for decades. It’s so dangerous that Montana voters banned its use in open-pit, heap-leach mining in 1998 after various disasters, including a 52,000-gallon spill at the Zortman-Landusky Mine. Montana taxpayers have paid more than $33 million to clean up acidic water from the mine polluted by cyanide and other heavy metals.
The Kilgore Gold Project is located on 8,000 acres of Forest Service land, and Excellon plans to build 10 miles of new roads, 140 drill pads, and 420 exploration drill holes on the mountainside above West Camas and Corral creeks.
GYC is a founding member of the Clean Kilgore Coalition, a group of ranchers, outdoor recreationists, families, and conservationists united in opposition to the Kilgore Gold Project since 2021. Together, we are working to protect the Centennial Mountains from the threat of an open-pit, heap-leach, cyanide gold mine and to ensure that this critical corner of the Greater Yellowstone Ecosystem remains intact for future generations.
We were able to partner with BYU-I and provide partial funding for this water quality monitoring study thanks to the generous support of the Mennen Environmental Foundation.
– Tom Hallberg, Idaho Conservation Associate [Driggs, ID]