British Columbia’s Copper Mountain mine is a dire threat to Washington waters and communities

British Columbia’s Copper Mountain mine is a dire threat to Washington waters and communities

Conservation Northwest / Aug 02, 2022 / Healthy Watersheds, Mining

Two new reports outline the catastrophic consequences of a tailings dam failure

SEATTLE, Wash. – The dams containing toxic waste generated by British Columbia’s Copper Mountain mine have an unacceptable probability of failing and inundating B.C. and Washington rivers and communities with poisonous sludge, according to two newly released reports.

The mine, located just 25 miles north of the Washington border, straddles a valley between Wolf Creek and the Similkameen River, which flows into Washington to meet the Okanogan River and eventually drains into the Columbia River. The threatened Similkameen Valley is home to several communities, with Princeton, B.C., just a few miles downstream, and includes territory of the Confederated Tribes of the Colville Reservation. The rivers are a source of critically important foods such as sockeye salmon, steelhead, and threatened chinook salmon, all of which would be harmed if either of the mines’ two dams failed.

Above is the tailings pond at Copper Mountain in British Columbia. Photo by Edgar Bullon. Click To View Location

The Colville Tribes and Conservation Northwest commissioned two reports to assess the probability and the likely impact of a dam failure. The results of both reports are startling

“The Colville Tribes would be directly affected by any spill at this site, but it should concern all citizens of Washington and anyone who wants a healthy and clean environment,” said Jarred-Michael Erickson, Chairman of the Colville Confederated Tribes. “Prevention of an accident is much better than a clean-up. Planning and precautions must be taken to keep our waters and communities as pristine as possible.”

Lynker Technologies modeled the results of dam failure in 62 simulation scenarios. They determined that even a mid-range scenario (the release of 40 percent of the mining waste) would release a debris flow that within 90 minutes would cover parts of the city of Princeton in over 30 feet of mining waste comprised of wet rock sediment. The flow would proceed down the Similkameen Valley, covering the Washington border with about six feet of sludge 24 hours after the dam failed. Impacts would continue into the Columbia River itself. Animation of this mid-range scenario can be viewed here. The full report can be found here.

A companion report by Dr. Steven Emerman, a geophysicist and international expert specializing in groundwater and mining, estimates an annual probability of failure of 0.45 percent with a range of 0.1-1 percent (1 in 1000 to 1 in 100). To clarify, a leading expert calculates the annual risk of a colossal and lethal dam failure at Copper Mountain at as high as one in a hundred. According to most U.S. and Canadian guidelines, the maximum annual probability of failure should be under one in a million.

“We in Washington state get no benefits from B.C. mining but plenty of risk and harm,” said Mitch Friedman, Executive Director of Conservation Northwest. “Washington leaders need to encourage their British Columbia counterparts to strengthen regulation of mining and resolve the perilous state of the Copper Mountain mine. The consequences are too dire to ignore.”

The two tailings dams at Copper Mountain mine are presently 566 feet and 540 feet in height, respectively, and are increasing by 15 feet a year. The company’s permit allows for 75 more feet in height, and Copper Mountain is considering an expansion of mining that would increase the permitted dam height to 853 feet – 250 feet higher than the Space Needle. This would make one of the dams the world’s second tallest. B.C. does not require an environmental assessment before issuance of a permit for that expansion.

The dams’ construction method, known as “upstream,” is banned in several countries due to its history of failure. According to experts, upstream tailings dams are an acceptable method only in the very safest circumstances in places with low precipitation and minimal chance of seismic activity. This location does not meet those and other criteria, including consistency of oversight and high functionality of dam monitoring instruments.

The dangers of a poorly regulated mine are not exaggerated. In 2014, the Mount Polley tailings dam breach disaster unleashed 25 billion liters of mine waste into nearby waterways in central B.C.

We urge British Columbia to act immediately to reduce the imminent threat to public safety and the health of our rivers and wildlife. Action is needed now to dramatically reduce the annual probability of failure of the Copper Mountain mine tailings dams. Ignoring the science creates an unacceptable risk to human lives, economic livelihood, wildlife and critical salmon populations.

Media Contact: Andrea Wolf-Buck, Conservation Northwest Communications Director:, 206-970-1430

Urge Gov. Inslee to demand that B.C. act now to protect our communities and waterways!

Learn more in this video about B.C. mining threats to Washington rivers:


See more of our work to protect Washington waters

“Keeping the Northwest wild” since 1989, Conservation Northwest is a regional non-profit organization that protects, connects and restores wildlands and wildlife from the Washington Coast to the British Columbia Rockies. Staff operates in local communities and rural areas around Washington and into southern B.C., using dialogue to find common ground and collaborative solutions for challenging issues including habitat corridors, wilderness conservation, forest restoration and endangered species recovery.