September was Public Lands Month, a celebration of America's iconic public lands and waters. In northern Minnesota, we're privileged to have access to a myriad of state and federal public lands, including the Superior National Forest and its iconic Boundary Waters Canoe Area Wilderness. During recent years, I've made annual October ruffed-grouse hunting forays into the Boundary Waters and have been stalking November whitetails in the surrounding Superior National Forest for going on a decade.

America's greatest hunter-conservationist, President Theodore Roosevelt, set the stage for the Boundary Waters in 1909 by establishing the Superior National Forest. As Roosevelt said in his first message to Congress, "The forest reserves should be set apart forever for the use and benefit of our people as a whole and not sacrificed to the shortsighted greed of a few."

Unfortunately, today, hunters, hikers, anglers, paddlers and many others are in the forefront of a battle to protect the Boundary Waters from copper-nickel sulfide mining proposals being pushed by foreign-owned mining companies. One of these companies, Twin Metals, is looking to build an industrial-scale sulfide ore mine a quarter mile from the BWCAW along the South Kawishiwi River.

"This gave hunters, anglers, hikers and paddlers alike pause," Spencer Shaver of Sportsmen for the Boundary Waters wrote for FirstLight Campfire in August. "Copper-nickel mining is responsible for massive stores of polluted water in North America, including Butte, Montana, the Gold King Mine in Colorado, and the Mount Polley Mine in British Columbia. By its nature, the removal of minerals from sulfide-bearing ore causes acid mine drainage (AMD), where mining tailings laced with heavy metals ... runoff into nearby ground and surface water."

In fact, every copper-ore sulfide mine in a water-rich environment like northern Minnesota's has contaminated surface and/or groundwater with AMD or toxic metals. That's a 100 percent failure rate, according to Water Legacy. As a result, the Kawishiwi River was named one of "America's Most Endangered Rivers of 2018" by the conservation group American Rivers.

Consequently, many regions with such mines ultimately see long-term negative economic impacts. As explained by Marshall Helmberger, publisher of the Timberjay newspapers in Ely, Tower-Soudan, and Cook-Orr, a recent Harvard study used a standard economic model to examine 72 different economic scenarios with and without mining. In all but three, the Ely area economy did better without mining than with it, he wrote.

According to statistics recently released by the U.S. Bureau of Economic Activity, nationwide, the outdoor recreation economy accounted for 2.2 percent of GDP ($412 billion) in 2016. Mining activities accounted for $61 billion, or 0.3 percent of GDP. The report also revealed that compensation for the outdoor recreation economy grew at a rate of 4.3 percent compared to 2.7 percent for the U.S. economy.

According to the LWCF Coalition, outdoor recreation in Minnesota supports 140,000 jobs, which generate $4.5 billion in wages and salaries that produce $1.4 billion annually in state and local tax revenues.

Given the seemingly unavoidable negative impacts of sulfide mining, it's not surprising that recent polling by the Save the Boundary Waters group showed that some 70 percent of Minnesotans oppose sulfide-ore copper mining near the BWCAW. By a 5-to-1 margin, Minnesota voters favor a gubernatorial candidate who would protect the Boundary Waters from the threat of sulfide-ore copper mining.

"Industrial mining a quarter-mile south of the Boundary Waters Canoe Area Wilderness, the most visited wilderness in America, makes no sense," said Land Tawney, Backcountry Hunters & Anglers president and CEO. "Short-term economic gains and a lifetime of cleanup must not be allowed to trump the solace, adventure and outdoor economic engine that is the Boundary Waters."

David Lien of Colorado Springs, Colo., and formerly of Grand Rapids, is a former Air Force officer and the founder and former chairman of Minnesota Backcountry Hunters & Anglers (backcountryhunters.org). He's the author of "Hunting for Experience II: Tales of Hunting & Habitat Conservation." In 2014, he was recognized by Field & Stream as a "Hero of Conservation."