Copper Sulfide Mining Threatens the Boundary Waters

Copper Sulfide Mining Threatens the Boundary Waters

The Boundary Waters Canoe Area is a beautiful place of pristine waterways and undisturbed boreal forest, with a wide variety of ecosystems supporting biodiversity and endless opportunities for back country canoe camping.  One of my most memorable camping experiences was canoeing and portaging through multiple lakes of the BWCA in northern Minnesota.  When a mining company proposed opening up the area adjacent to the Boundary Waters to copper mining, there was public outrage.  Mining threatens to contaminate clean waters with leaks from its stored toxic waste.  Yet demand for copper continues to grow and new mining sources are sought worldwide.  We depend on copper for modern conveniences like electrical wiring, plumbing pipes, computers and mobile phones.  Mining copper and other precious metals is coming at the price of our most treasured environmental resources in valued regions around the world, and serves as a warning for the proposed mining near the Boundary Waters in Minnesota.

(image:  Pictured Rocks National Lake Shore, credit:  Gregg Bruff, NPS, wikimedia commons)

Where is copper sulfide mining occurring?

Bingham open pit copper mine. Image credit: Raymond M. Coveney, Wikipedia Commons.

Copper is mined all over the globe, with the majority coming from Chile, Mexico, Peru and Indonesia.  The largest open pit copper mine in the world, the Bingham Canyon Mine found in Utah, is three miles wide and one mile deep. Arizona boasts that it has been the leading copper producing state, producing over 60,000 metric tons of copper per month in 2019, over half of the total U.S. production.

Mining often garners support in economically depressed regions because of its promise of new jobs.  In Minnesota, two mining companies promise to provide 1060 jobs at its proposed mines.  The proposed Copper Flat Mine in Sierra County, New Mexico is promising 400 direct jobs for about 10-12 years.  Jobs are just as easily taken away when mining operations shut down.  In Manitoba, the community of Flin Flon will lose 900 jobs, and likely experience an economic depression when it closes in 2021.


The sulfide mining process and its aftermath

The Animas River after Gold King mine spill. Photo source: Riverhugger, wikimedia creative commons.

Copper sulfide mining extracts sulfide ores which contain metals that are bonded to the sulfur.  The process breaks apart the ore, exposing it to air and water, then soaks it in chemicals to release copper and other minerals.  A small percentage of the ore is actually metal, most of it is sulfide that turns to sulfuric acid in the process.  The leftover rock is called “tailings,” and amounts to millions of tons of waste rock that is stored either in a wet slurry, or dry stacked.  The chemicals created by exposing sulfides to water and air creates sulfuric acid, something akin to battery acid.  It also leaches out other metals like mercury and lead, producing Acid Mine Drainage.

Tailing ponds remain in perpetuity and are hazardous because a leak or breach in a dam could result in acid spilling out to the surroundings and spreading through waterways.  It is impossible to prevent seepage into the ground.  Dry stack is supposed to be less detrimental for waste because it is not in a liquid form that could spill, but it still is criticized for its potential pollution through leaching– when it rains, chemicals leach from the waste into soil and water, and can also spread pollution through toxic dust.


“The copper will go to China, the profits will go to the investors, and we’ll get left with a massive hole in the ground, and, very likely, toxics in our groundwater.” — Save the Scenic Santa Rita, New York Times, 03/21/12

Although copper mining has not occurred in Minnesota, the state has a long history of mining for iron ore, which is a different process typically not involving sulfides and carries less risk for sulfide contamination.  However, during iron ore mining at the Dunka Mine in the 1960’s, an area of sulfide containing rock was encountered and moved to storage.  The mining company has since gone bankrupt.  Runoff from the stored rock contains leached toxic chemicals that flow into nearby waterways. Efforts made in the 1970’s to establish water treatment haven’t prevented contaminated water from escaping.  In fact, the water treatment plant is now closed.  Although the current owner meets Minnesota requirements for monitoring the water, they do not meet Minnesota water quality standards.  Minnesotans are paying the environmental cost now for past mining.

Sulfide Mining and Water do not Mix

Lake Iliamna, Alaska. Credit: NPS

Most copper mines in the United States are in the arid southwest. But as new areas are explored by mining companies, they are getting uncomfortably close to valuable groundwater sources and protected landscapes.


Arizona, which is no stranger to mines, is finding that the mining proposal for the one-mile wide Rosemount copper mine is close to the Cienega Aquifier, native american sacred land, and a wildlife corridor with unique species.  Not just the mining process itself would pollute the region, but the storage of the tailings pose an even greater threat.  The plan includes 1.2 billion tons of waste rock that is contaminated with toxic chemicals that would be dumped within range of streams that lead into Davison Canyon.  The proposal claims that it will not create tailing ponds, instead using the “dry stack” method of storage.  However, critics say that rainwater would get into the tailings stacks, infiltrating and taking the toxic waste into the groundwater as it drains.  The region includes the Davidson Canon Wash and Cienega Creek, wetlands that are protected by the U.S. Clean Water Act.  Permits are in process, lawsuits are pending, and the group Save the Scenic Santa Ritas is not giving up the fight to prevent building of the mine.

“Most of us support responsible development.   However, development that comes at the expense of our clean water is not responsible.”  Duluth Tribune, 01/04/19.

The same conflict of interest between international mining companies and local citizens that value their water, landscape and wildlife is being waged in Alaska.  The proposed Pebble Mine would be located at the headwaters of salmon producing rivers, threatening the region’s prized salmon population with the possibility of devastation by toxic contamination from an accidental breach of stored mining tailings.  The tailings would need to be managed for generations to come, a liability for future generations.  Besides the mine itself, miles of new roads through pristine wilderness and a crossing at Iliamna Lake with a new ferry terminals are proposed for transport.  A new port for shipping the mined metals is proposed for the wild Amakdedori Beach on the western coast of Cook Inlet.

The  expansion of copper mining to areas encroaching on valued ecological habitat is played out over and over again throughout the U.S. and elsewhere:

Marquette, Michigan:  The Eagle Mine, opened in 2014 dumps contaminated wastewater directly into springs that feed a river and threatens to contaminate the headwaters feeding into Lake Superior.

Kvalsund, Norway:  A proposed mine will dump two million tons of tailings into the Repparfjord, a National Salmon Fjord, home to salmon spawning grounds.

Tsilhqot’in Nation, British Columbia:  A proposed mine in First Nation territory threatens to damage a sacred site at Fish Lake.

Huasco, Chile:  Mining waste is being dumped directly into the sea, destroying marine life in Chapaco Bay.

Holden Village, Washington:  Mine tailings stored in the so-called “dry stacking” method totalling almost 10 million tons remain in a massive dump site near Lake Chelan release toxic water that flows into Lake Chelan and then to the Columbia River.

“Not this mine. Not this location.” — Star Tribune, 11/23/19

Map by Kmusser in creative commons, with modifications.

In northern Minnesota, there are two mining companies proposing mines within valued watersheds.  The Polymet mine would be in the watershed that flows to Lake Superior.  The Twin Metals mine would be in the watershed that flows to the Boundary Waters. They are in an area rich in mineral resources.  But should every area rich in minerals be mined?  And at what cost?  The evidence shows that stored mining waste contaminates its surroundings, despite regulatory requirements, and leaves the burden for clean up on future generations.  The Boundary Waters is a sensitive region of connected waterways and wetlands.  An accident, a leak, could mean a disaster for the entire region.

Environmental Risks of Copper Mining

Acid Mine Drainage. in North Lima, Ohio. Photo credit: Jack Pearce, wikimedia creative commons.

The risk for toxic contimination from tailings pilings is not unfounded.  Just ask the people of Likely, British Columbia, who witnessed a dam collapse in 2014 at Mount Polley mine that allowed toxic chemicals to flow into Quesnel Lake.  Pollution from mining tailings is unfortunately common.  According to the Chronlylogy of major tailings dam failures, just in the last two years (2018-2019) tailings failures have occurred multiple times in Brazil, Mexico, Peru, Myanmar, India, and Australia.   A 2012 review of 14 copper sulfide mines in the US found that all of the mines (100%) had pipeline spills or other accidental releases.  Damage to waterways usually occurs:  92% of them had significant water quality impacts.  The Typrone and Chino mines in New Mexico will require water treatment forever for the estimated two billion gallons per year of seepage that is contaminated with acid and metals.  These are in arid locations.  According to Earthworks, research shows that mines that are close to groundwater have an even higher risk of contaminating water.

Local Advocacy Success in Protecting Public Lands

Methow River. Photo credit: Benjamin Cody.

When local communities come together to take a stand, they can protect their region.  For years, businesses and residents in central Washington fought for protection of the Methow Valley region of the state.  They had the support of Conservation Northwest, the Mountaineers, and other organizations.  In 2019, the region was permanently protected with the John D. Dingell, Jr. Conservation, Management and Recreation Act, which included permanently withdrawing 340,079 acres in the Methow Headwaters from new mineral exploration and mine development.

The future of copper

Demand for copper is expected to grow significantly in the upcoming decades.  It is needed for not only the household and electronic gadgets that have become so common in modern life, but also for the parts needed for future electrified energy, including electric vehicles, solar photovoltaic systems, and wind turbines. 

Estimated copper demand through 2100. Credit: Resources, Conservation and Recycling. Creative Commons.

According to Reuters, mining companies are “working feverishly to develop new mines and bring fresh supply online as the electrification trend envelops the global economy.”

The copper industry appeals to the public by claiming that more mining is needed to produce the copper needed for sustainable energy uses.  Do we have to make a choice between mining that leaves toxic waste behind to infiltrate our water and so-called “green” technologies?  While copper and other metals such as lithium and cobalt are required for clean energy technology, there are other growing industries that are gobbling up copper resources, including the rapidly growing construction and electronics industries.  Cars and homes take tremendous amounts of copper to build.  The world is becoming as addicted to metals as it is to oil.   There is ongoing debate on what percentage of the copper industry expansion is due to electrification of power.  At the same time, it is undeniable that global economic growth in buildings, utilities, vehicles, national defense and electronics is a fundamental basis for copper demand.  As a limited resource, copper demand will reach a peak at some time in the future. 

In the familiar reminder to Reduce, Reuse, and Recycle, following these principles for copper and other mineral resources are an important part of the solution.  When sourcing theses products, whether from a nearby region that is dear to us or from a distant part of the earth, it is essential to ensure that both environmental and human rights standards are met.

More Resources

Here is an explanation of stakes involved to protect the Boundary Waters region from copper sulfide mining:


Here is short video about how copper is mined and produced:


The legislative hearing in February 2020 on H.R. 5598, the Boundary Waters Wilderness Protection and Pollution Prevention Act, that proposes permanent withdrawal of approximately 234,328 acres of the Superior National Forest that is in the watershed of the Boundary Waters from mineral mining, while still allowing the removal of sand, gravel, granite, iron ore, and taconite:

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