East Boulder Mine Dam Failure Would Devastate Watershed, Agricultural Lands and Infrastructure, Simulation Shows

Conservation groups urge Forest Service and DEQ to consider safer methods for mine waste storage

Today, conservation groups released two videos simulating the devastating effects of a dam breach at a new tailings storage facility proposed at the East Boulder Mine on public lands in the Custer Gallatin National Forest. Such a failure would inundate ranch lands, homes and infrastructure with hazardous mine waste. 

Video Simulation 1 – Stop Motion 
Video Simulation 2 – Flyover

Earthworks, Montana Trout Unlimited and downstream residents are urging the Forest Service and Montana Department of Environmental Quality to consider a method for storing mine waste, known as dry or filtered tailings, that tailings dam experts consider to be the best available technology for preventing catastrophic failure. The agencies are currently evaluating the proposed expansion, which will store 1.17 trillion gallons (5.8 million cubic yards) of additional mine waste in the Lewis Gulch Tailings Storage Facility perched above the East Boulder River, a tributary to the Boulder River, which flows into the Yellowstone River near Big Timber, Montana. The Forest Service and DEQ are expected to release a Draft Environmental Impact Statement of the proposed expansion for public review and comment this spring. 

“Healthy rivers like the Boulder and Yellowstone are the heart of my livelihood, as well as the lives and jobs of many Montana ranchers, farmers, municipalities, and, frankly, all Montanans,” said Dan Vermillion, downstream owner of Sweetwater Travel Company and former Montana Fish & Wildlife Commissioner. “Big Timber,  the Boulder, and all of the downstream water users deserve state-of-the-art protections if the mine aims to nearly double the waste its stores in the river’s headwaters.”

“The Boulder Valley is a scenic treasure, a remarkably undamaged natural resource that can hardly be improved,” said Thomas McGuane, Boulder valley resident and author. “There is no question that the Stillwater Mining Company needs storage for mine waste; but better technology is available than what they have proposed. The Boulder Valley must seem far away to a company whose offices are in South Africa; but we in Montana are at close range and want the best science available in protecting what we have.”

“I live under Goliath’s spear,” said Noel Yantos, downstream resident on the East Boulder. “A failure of the tailings pond will destroy everything I have with zero insurance coverage for that failure. I want the mine to be successful. I know that there are options, such as dry tailings, to reduce the downstream risks. I urge a close look at these options. It would certainly make us all sleep better.”

“Nothing is more precious than clean water, which a massive failure of this facility could threaten, along with causing irreparable damage to fish, wildlife, property and people,” said David Brooks, Executive Director of Montana Trout Unlimited. “These animations show how catastrophic an event like this could be and should lead us all to support the best possible protections for the East Boulder River.”

“Public health and safety must come first when considering the options for long-term mine waste disposal at the East Boulder Mine,” said Bonnie Gestring, Northwest Program Director at Earthworks. “Despite industry promises, the reality is that tailings dams fail, and severe tailings dam failures are happening more frequently. It’s essential that the agencies consider the most protective options during the mine permitting process.” 

Public concern about tailings dam safety has escalated over the last decade, as the rate of severe tailings dam failures has increased globally. In the wake of the 2014 tailings dam failure at the Mount Polley Mine in Canada, a panel of engineers released a report emphasizing the need for an industry-wide shift in tailings storage, recommending filtered or dry tails as the best available technology to reduce the potential for catastrophic tailings dam failures. 

The simulation, produced by engineering firm Lynker, is based on the mining company’s own dam breach assessment. The East Boulder Mine is owned by Sibanye Stillwater Mining Company (NYSE: SBSW), headquartered in South Africa.

The Boulder River watershed, which originates in the Absaroka Beartooth Wilderness Area, is valued for its wild trout fishery, high-quality recreation and tourism, and the essential water that it supplies to agricultural interests and downstream communities.