Rainfall and run-off events in 2008 and 2009 forced the company to ask for amendments to its water license to release untreated water into the Yukon River system. In 2008 heavy rains resulted in flooding and the mine’s water treatment plant was overwhelmed resulting in the release of some 350,000 cubic meters of untreated water into the Yukon River, and the effluent content (.05 mg per litre) was higher than Yukon license standard of .01 mg per litre. Ironically the water storage pond had been designed to assure water availability throughout the year, given an expectation of occasional seasonal summer drought. The 2008 rainfall also washed out a four kilometre section of the mine haul road to Minto Landing, linking into the Klondike Highway. In 2009 the problem of excess water on the mine-site, this time attributed to unusually heavy spring melt, was exacerbated because the wall of as storage pit was partially collapsing because of permafrost melt, and 750000 CM of water were discharged into the Yukon River system.
Since 2007, Capstone Resources Minto mine has made a number of modifications to deal with unanticipated extreme precipitation events and permafrost degradation Minto mine was planned in the early 1990’s when a changing climate was not a major consideration. Minto is the largest operating mine in the Yukon, and in 2013 will be the only one operating on a year round basis. Planned in the 1990’s and opened in 2007, the mine is located in the discontinuous permafrost zone 240 km north of Whitehorse close to the Yukon River in the Traditional Territory of the Selkirk First Nation. Initially it was expected that the Minto venture would yield 371 million pounds of copper over an anticipated life-span of eight years. The mine has expanded several times since inception, and recent discoveries are expected to extend mine life beyond 2020. Climate related problems including flooding and permafrost degradation have beset the mine ever since it opened, and the nature of these problems and the manner in which Capstone has responded illustrate both the way in which a changing climate is manifest and the challenges faced by a mine responding and adapting as problems arise. The Selkirk First Nation, located down-stream from the mine has a strong vested interest in the maintenance of the region’s environmental integrity and is a major player in ensuring that negative externalities from the mine-site are minimized.