The Mount Milligan mine — an open-pit gold and copper mine located some 90 km northeast of Fort St. James — has been pumping water from a nearby fish-bearing lake since February.
Thompson Creek Metals Company (TCMC) received permission from the province in January to pump water from Philip Lake, which supports at least seven species of fish, including redside shiner, burbot, northern pikeminnow, mountain whitefish, rainbow trout, lake whitefish and white sucker, according to the B.C. Ministry of Environment.
The lake is part of the Philip Lakes chain, which is listed as a camping and fishing destination on the province’s Recreation Sites and Trails website.
In early December, the company applied for an amendment to its Environmental Assessment Certificate (EAC) to draw water from Philip Lake. The Environmental Assessment Office (EAO) — a government agency that reviews major projects in B.C. — determined that “significant adverse effects” to fish and fish habitat were unlikely, according to Danielle Bell, a ministry spokesperson.
“TCMC is considering additional amendments in 2018 to secure a long-term water supply,” she added.
Water from Philip Lake is meant to help power the company’s ore-crushing mills following a dry year in 2017 followed by deep-freeze conditions in December, which reduced the supply of clean water needed to feed the mills, said John Pearson, vice president of investor relations for Centerra Gold. TCMC was purchased by Centerra, a Toronto-based company, in 2016.
Pearson said that thawing conditions and a gradual build-up of water were mostly responsible for bringing the mills back online.
“The main source of the water is spring run-off from the melting of the snow pack,” said Pearson, adding that other sources include tower drains and groundwater. Philip Lake provides a fraction of the total supply, “but every little bit helps,” he said.
The company had temporarily suspended milling operations in late December due to a water shortage, said Pearson, adding that the first mill was brought back online on February 5, followed by the second on March 23.
The mine processes about 40,000 tonnes of ore daily, and the spring melt will eventually bring capacity to 55,000 tonnes per day, said Pearson. He said no layoffs occurred at the mine during the suspension of milling operations, as the company focussed on tasks including stockpiling ore and building a tailings dam. The mine employs some 500 workers.
The mine began operations in 2014, and is expected to have a 21 years left in its lifespan, said Pearson, who added that further exploration could extend that period.