The commitment of Minnesotans to protect the land and waters that are now part of our Boundary Waters Canoe Area Wilderness began in 1902. That year, Gen. C.C. Andrews, the Minnesota forestry commissioner, persuaded the U.S. Land Office to withdraw from homesteading 500,000 acres in what is now the Boundary Waters. From 1905 to 1908, the Land Office withdrew another 659,700 acres. This farsighted action paid off handsomely when President Theodore Roosevelt created the Superior National Forest in 1909. The Boundary Waters spreads across 1.1 million acres of this spectacular 3-million-acre National Forest.

Now, our government has undertaken study of another sort of land withdrawal to protect the Boundary Waters. This past January, the U.S. Forest Service and the U.S. Bureau of Land Management began a two-year process of preparing an environmental-impact statement (EIS) to determine whether 234,328 acres of National Forest lands near to and upstream from the Boundary Waters should be withdrawn from the federal mineral leasing program for 20 years. This process is specifically authorized by two long-standing U.S. laws: the Federal Land Policy and Management Act and the National Environmental Policy Act. Both were passed in the 1970s and have been applied many times, by both Democratic and Republican administrations, to evaluate threats to lands owned by the people of the United States.

The decision by the agencies to undertake this study followed years of work by their professional staffs to understand the Boundary Waters ecosystem, the economic and social value of the Boundary Waters, and the nature of the threat posed by sulfide-ore copper mining. Beginning in 2013, business owners, sportsmen and -women, and other citizens presented the agencies with overwhelming evidence of the harm that would be done to the Boundary Waters if sulfide-ore copper mining were allowed in its watershed.

During the "scoping" portion of environmental review, which ended on Aug. 17, people had the right to submit written comments and ask the agencies to include specific issues in the study. More than 3,000 people attended listening sessions in Duluth, St. Paul and Virginia. Citizens speaking in favor of protecting the Boundary Waters outnumbered mining supporters by almost 2 to 1. More than 125,000 written comments were submitted to the agencies. This is the largest public involvement in an EIS in the history of Minnesota. It is consistent with polling that shows support of the EIS by 79 percent of Minnesotans and opposition to copper mining near the Boundary Waters by more than 2 to 1.

Minnesotans understand that we cannot afford to get this wrong. Will we continue Minnesota's commitment that began more than a century ago and take steps to ensure that the Superior remains a healthy multiuse national forest? Or will we instead allow the destruction of many thousands of acres of this beloved public land, upstream from the Boundary Waters, by permitting a single-use industrial hard-rock mining district, with the inevitable acid mine drainage that would seriously harm aquatic ecosystems downstream? The watershed of the Boundary Waters is simply the wrong place for this kind of mining.

The Trump administration has wisely chosen to let our professional land managers perform their job and continue the study. This is crucial to the well-being of the Boundary Waters and to the sustainable economy of wilderness-edge communities. Economic studies show that sulfide-ore mining in the watershed would do major damage to existing businesses, jobs, income and population.

But as Minnesotans well know, the value of the Boundary Waters extends far beyond mere economics. A recent scouting magazine article about our secretary of state begins with this sentence: "You could say Rex Tillerson's path to the corner office began on a portage trail in the Boundary Waters of Minnesota and Ontario." The Boy Scouts of America has sent hundreds of thousands of kids into the Boundary Waters since 1923. It is in good company. The Girl Scouts, YMCA camps, Voyageurs Outward Bound School, Wilderness Inquiry, church and community groups, and many other organizations — as well as countless families — have given kids unforgettable outdoor adventures and imparted life-enriching lessons by taking them on Boundary Waters canoe trips.

We must be true to the Boundary Waters and the people who depend on it.

Walter F. Mondale is a former vice president of the United States and former U.S. senator from Minnesota.