Investigation urged into Canadian mining waste in Montana The renewed urgency comes as Canadaâs largest diversified mining company lays plans to expand its footprint by building new mines along the border without a tested strategy in place to treat the chemical-laden flows Author: Tristan Scott Associated Press Even with the U.S.-Canada border restricting travel for at least another month, the international exchange of mining waste leaching from British Columbia into a transboundary watershed touching Montana and Idaho has continued unmitigated, intensifying concerns to such a degree that in the span of 10 days in June a rare confluence of global entities has paid heed to an environmental calamity that’s been brewing for more than three decades.