TIMELINE: Yellowknife’s Giant Mine

WATCH ABOVE: A preview for 16×9’s “Contamination Nation.”

The lure of gold helped build the fledgling northern community of Yellowknife when the Giant Mine site opened in 1948, but that development came at a heavy cost. For more than 50 years, the mine pumped arsenic into the air, contaminating people, water and land. What didn’t go up the stacks was squirreled away in the deep, dark mine shafts below the ground and forgotten, until recently. Today, there’s enough arsenic buried there to kill everyone on the planet, and the federal government is racing to contain the poison before it leeches into life-sustaining land and waterways. It will cost a billion dollars to stabilize the site, and that’s only a small part of the toxic legacy of development.


The Klondike Gold rush ends and eager prospectors begin arriving in Yellowknife. C.J. “Johnny” Baker and H. Muir make their way to the northern shores of Great Slave Lake and stake 21 “giant” claims.

Story continues below advertisement


Giant Mine begins gold production and operates without pollution control.


Airborne arsenic emissions at Giant Mine are estimated at 7,500 kg per day. Today, the World Health Organization says, it can’t recommend any safe level for airborne arsenic exposure.


The local Yellowknife Dogrib Band says they lost four children from drinking arsenic-poisoned water.


April – Government documents obtained by 16×9 show a Dene child in Yellowknife died after drinking melted snow contaminated with arsenic trioxide. The family is given $750 for the loss of their son by Giant Yellowknife Gold Mines Ltd.

Story continues below advertisement

The government and Giant Mine start to act on the arsenic problem. In October, Giant Mine installs a device called a cottrell electrostatic precipitator (ESP) to capture arsenic and control emissions at Giant Mine.

READ MORE: Toxic dust buried under Yellowknife’s ‘Giant Mine’ to cost taxpayers $900M

Meanwhile, the Yellowknife Medical Health Officer places small advertisements in the local paper warning people to be cautious when using water from spring runoff.

However, former Dene chief Fred Sangris tells 16×9 that the warnings were useless as local Dene couldn’t read.


Airborne arsenic emissions drop to an estimated 3,288 kg per day.


Airborne arsenic emissions drop to 200-300 kg per day.


The government starts its first major study into how the arsenic is affecting people. However, results of the study would not be made public until 1975.


After pressure from the media, the 1966 government study is released to the public. The government tries to reassure citizens the situation in Yellowknife is under control and there was no cover-up.

Story continues below advertisement

However, a memo obtained by 16×9 between Yellowknife and Ottawa tells a different story.

“It was apparently decided at the time that the report should not be made public because it might cause alarm on the arsenic question.”


The National Indian Brotherhood grows frustrated with the federal government. It releases its own study along with the United Steelworkers and University of Toronto’s Institute for Environmental Studies. The study finds high levels of arsenic in mill workers and Aboriginal children.

Story continues below advertisement

In response to the National Brotherhood’s study, the Canadian Public Health Association (CPHA) Task Force on Arsenic is created.


Airborne arsenic emissions drop to 13 kg per day.


Royal Oak Resources Ltd. gains control of Giant Yellowknife Gold Mines Ltd.


Royal Oak Mines goes into receivership and is sold to Miramar Giant Mine Ltd. As a condition of the sale, the federal government acknowledged that Miramar would not be responsible for the arsenic trioxide stored underground.


SRK Consulting wins international competition to become lead technical advisor on the management of arsenic trioxide dust.


Miramar finishes work at Giant Mine and it officially becomes an abandoned mine site.


The Giant Mine Remediation Project team begins work on a detailed remediation plan. Work is expected to begin in 2017.


May: SRK Consulting Inc. prepares an executive summary of the Giant Mine Remediation Plan for Aboriginal Affairs and Northern Development Canada.

Story continues below advertisement

April: The City of Yellowknife refers the project to Mackenzie Valley Review Board for Environmental Assessment.


The environmental assessment at Giant Mine begins.


Giant Mine is classified as a Class 1 federal contaminated site meaning it has the highest possible risk.


March: A new cost of $903.5 million was approved by Treasury Board for the Remediation Plan.

Months later at a public hearing, Aboriginal Affairs and Northern Development Canada still says the cost for the remediation plan will be $449,615,993.


June: The Yellowknives Dene, City of Yellowknife and Alternatives North write a letter urging the federal government to accept the review board responses.

August: The federal and territorial ministers approve the environmental assessment.

October: More than 22,000 contaminated or suspected contaminated sites remain across Canada, listed in the Federal Contaminated Sites Inventory.


The Giant Mine Remediation team is expected to complete C-Shaft Headframe stabilization by the summer of 2015.

Story continues below advertisement


The Giant Mine Remediation Project is expected start the bulk of the remediation work.


The Giant Mine Remediation Project is expected to enter the final phase, “monitoring and maintenance.” This is the longest phase of the project and is expected to last at least 100 years.


© Government of Canada. Reproduced with the permission of the Minister of Public Works and Government Services Canada (2014).
Source: Library and Archives Canada/Department of Indian Affairs and Northern Development fonds/File 139-7.

© Government of Canada. Reproduced with the permission of the Minister of Public Works and Government Services Canada (2014).
Source: Library and Archives Canada/Department of Health fonds/File 851-5-2/Part 2.

16×9’s “Contamination Nation” airs this Saturday at 7pm.

Sponsored content