Newspaper article The Canadian Press

Giant Gold Mine Left High Arsenic Levels in Yellowknife-Area Lakes: Research

Newspaper article The Canadian Press

Giant Gold Mine Left High Arsenic Levels in Yellowknife-Area Lakes: Research

Article excerpt

High arsenic levels found in Yellowknife lakes

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Research has found that levels of toxic arsenic in lakes circling a former gold mine on the outskirts of Yellowknife exceed guidelines for human and environmental safety.

It's another level of complexity to what is one of Canada's biggest environmental cleanups. About $1 billion in tax dollars is already earmarked to deal with the defunct Giant Mine, where 237,000 tonnes of arsenic sit underground on the shores of Great Slave Lake.

Two new studies are among the first to look at the impact of the mine's operations on lakes outside the mine property.

"Concentrations of arsenic are well above drinking water quality guidelines and protection of aquatic life for lakes within 17 kilometres of the Giant Mine," says an academic paper released Wednesday and co-authored by Jules Blais of the University of Ottawa.

A 17-kilometre radius is big enough to include most of the city of Yellowknife.

The territorial capital gets its water from the Yellowknife River, which flows near the mine. But the river's watershed is big enough to keep the arsenic low. The city also tests for arsenic.

A Northwest Territories government study concluded that 45 of the lakes within 30 kilometres of the mine had arsenic levels that exceeded drinking water standards.

The Giant Mine was the city's economic mainstay for 56 years before it closed in 2004.

Its gold was locked within crystals of arsenopyrite, a mineral that contains iron, arsenic and sulphur. Most of the arsenic was blown back underground, where huge dustpiles of it sit in 15 subterranean chambers, some big enough to swallow an 11-storey building. About 3,600 cubic metres of arsenic and arsenic-contaminated material also remain in surface structures. …

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