A global human-rights organization has joined the chorus speaking out against the PolyMet copper-nickel mine in Northeastern Minnesota, with officials from the group calling the proposed mine as much a human rights issue as an environmental one.

Officials and members of Amnesty International were in Duluth teaming up with state and local opponents of what would be Minnesota's first-ever copper mine. They held a rally and press conference in the Duluth City Hall rotunda saying the copper mine has the potential to be damaging to tribal rights, human health and downstream environments.

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'"Human Rights and environmental justice go hand in hand," said Gary Anderson, a Duluth city councilor and outspoken critic of the PolyMet proposal, at the event.

Amnesty International and other PolyMet foes have been meeting with local and regional officials in recent days, including members of the Fond du Lac Band of Lake Superior Chippewa. That includes Amnesty members from British Columbia, site of a major copper-mine dam failure in 2014.

The Mount Polley disaster occured when a large dam that held back mine-tailings waste rock was breached on Aug. 4, 2014, spurring a massive gap in the dike that sent millions of gallons of mine waste and water downstream into Quesnel Lake. A 2015 report concluded that the dam failed because it had been altered beyond orignal engineering specifications. Other findings suggested that wet storage be replaced with dry storage of mine waste.

But since then there have been no fines, no criminal prosecution and no one held accountable for the mess, said Doug Watt, who lives on Quesnel Lake about 5 miles downstream from mine.

Watt said there have been noticeable changes in what had been a pristine mountain lake, including never-before-seen outbreaks of blue-green algae and areas of slime.

"It's not just heavy metals'' concerns when mine waste spills "but there are nutrients, too, and nitrates," Watt said at the Duluth event, warning Minnesotans not to trust the promises of mining officials, engineers or regulatory agencies. Provincial officials promised to restore Quesnel Lake to pre-spill conditions and to hold someone accountable for the disaster. But "none of that happened," Watt said. In fact the company is now being allowed to dump some mine waste directly into the waterway.

"We don't want that to be your story" in Minnesota, said Tara Scurr of Amnesty International Canada.

PolyMet's man-made tailings basin and dam will sit partially on top of one left over from the LTV Steel Mining Co. iron ore operations at the same site. The earthen dam will reach 252 feet high when finished, holding back millions of gallons of water mixed in a slurry with finely ground rock left over after crushing and processing - after the copper, nickel and other valuable metals are extracted. Eventually the PolyMet tailings basin will cover 2½ square miles with 10 million cubic yards of mine waste pumped in each year for 20 years.

PolyMet officials have said a Mount Polley-like disaster at their facility is unlikely, and that the comparison is unfair, in part because their dam will have far less slope (13 percent grade compared to 77 percent) and because the region's topography is much flatter.

The former LTV "dam has been in existence for more 60 years without any major incident. We'll simply be adding to it, but also making some enhancements as well," said Bruce Richardson, PolyMet spokesman. He noted that several such tailings dams operate without any major incidents across the Iron Range.

Even if the dam did fail, PolyMet says the tailings waste will be nontoxic and non-acidic and won't cause the kind of downstream acid mine pollution that critics of the mine fear.

State and federal agencies currently are weighing operating and emissions permits PolyMet needs to start mining operations, with public comments on the state permits accepted into March. The mine would employ about 300 people with an open pit near Babbitt and a processing center near Hoyt Lakes.

London-based Amnesty International was formed in 1961 and claims to have 7 million members globally. It has focused on human rights but also native peoples' rights and environmental justice.