Drillers for Twin Metals pulled a core sample from the drill pipe at a site near Ely, in northern Minnesota, in May 2013. (The Minnesota Star Tribune)

I remember the day the Mount Polley mine failed. Mount Polley is a copper and gold mine in British Columbia, and on Aug. 4, 2014, a tailings basin dam catastrophically failed. Four short days later, the nearly 1,000-acre tailings basin was largely empty, having released 26 million cubic yards of water, silt and toxic tailings into nearby lakes and rivers.

I remember that day because I was sitting at my desk as the forest supervisor of the Superior National Forest, heading into yet another meeting to discuss the potential development of the Twin Metals copper mine immediately adjacent to the Boundary Waters Canoe Area Wilderness. In particular, I remember a short clip of a manager at Mount Polley shaking his head, looking shellshocked and saying: "If you would have asked me yesterday if this could happen, I would have told you NO WAY, just no way."

I had a lot of empathy for that guy. Clearly, this wasn't the result he wanted. At the same time, I thought, how could you not have anticipated something like this? Why would it be such a surprise? The history of copper mining clearly demonstrates that the vast majority of these mines fail. They may fail catastrophically, or they may leak contaminants over time, leading to inevitable environmental damage or collapse.

But there is no denying that at some point in the construction, operation or the extremely long-term reclamation phase of these mines, there is a very high probability of failure. It is indisputably a high-risk business, and there is no mine plan or design feature that eliminates the risk.

While I was forest supervisor, I worked with the U.S. departments of the Interior and Agriculture and Forest Service leadership to thoroughly examine the decades-old mineral leases held by Twin Metals Minnesota and its parent company, Chilean conglomerate Antofagasta. The Department of the Interior spent more than 1½ years delving deeply into the history and language of the leases and determined that Twin Metals did not have an automatic right to the leases.

The review was long, broad and deep. Based on that determination, in 2016, Tom Tidwell, then chief of the Forest Service, used his regulatory authority to deny consent to renewal of the leases, citing a host of environmental, social and economic concerns, as well as the best available science. In a matter of months after the Trump administration took office, the Department of the Interior reversed its own decision with a shallowly defended new decision that can only be described as a "political do-over." Law and science quickly took a back seat to a political agenda.

Recently, former Agriculture Secretary Tom Vilsack, Tidwell and I came together once again to say that the proposed Twin Metals mine is neither ecologically nor economically sustainable. Collectively, we have decades of experience supporting the multiple-use mission of national forests, but we know that not all uses are appropriate in all places. We firmly believe that the cost — the trade-off — of a copper mine in this place is the Boundary Waters.

Once the mine fails, there is simply no way to contain it without sacrificing the wilderness and the long-term economic sustainability that it supports. All of the science and all of our experience tell us that in this extremely valuable, water-rich and highly interconnected place, you simply cannot have both.

As the Bureau of Land Management fast-tracks the unlawful renewal of the old leases and quietly prepares for issuing additional leases, National Forest leadership continues to feign powerlessness and Twin Metals furiously works on its mine plan of operations, I know that it is difficult not to get discouraged or feel that the cause is already lost. But I can honestly tell you from experience that the voice of the public can and very often has changed the course of the oncoming train. There is still opportunity. We must continue to speak up, we must stay engaged and we must ensure that our grandchildren won't ever have to say: I remember the day the Twin Metals Mine failed. I remember the Boundary Waters.

Brenda Halter, of Duluth, is retired from a 23-year career with the U.S. Forest Service. She was forest supervisor of the Superior National Forest from 2012 to 2016.