Three Northwest Territories aboriginal groups will face off next week against the world's biggest diamond mining company over chloride levels in Snap Lake.

Since diamond mining began at De Beers' Snap Lake in 2008, the chloride content of the mineral water lake has been increasing to the point where there is now more than 100 times more chloride in the water than before the mine was built.

The chloride and other salts are coming from waste water being pumped from the underground mine into the lake. There is more water being pumped out of the mine than De Beers predicted.

The territorial government is threatening enforcement action against De Beers and is now taking water samples that could support a prosecution.

If De Beers is not in compliance with its water licence, the company's contingency plan is to shut down the mine, but it's also working on other solutions.

At a public hearing next Thursday, De Beers will ask to double the chloride limit. The current limit is already two-and-a-half times the level recommended for the protection of fish.

Three aboriginal groups will be at the hearing, including the Lutsel K'e Dene First Nation. In letters to the Mackenzie Valley Land and Water Board, it recommends that instead of raising the limits, De Beers reduce the amount of chloride in the mine water it's pumping into the lake. 

It is also concerned the plume of waste water will eventually reach downstream to its sacred Lady of the Falls site on the Lockhart River.

The territorial government predicts, if chloride levels in Snap Lake continue to climb as they have so far, it will take 90 years after the mine closes for the lake to return to its original levels.

De Beers encountered the same problem at its Victor diamond mine in Northern Ontario. According to Environment Canada, chloride limits in the water licence for that mine have been increased twice to keep the mine operating legally, to the point where they are now more than 10 times the level recommended for the protection of aquatic life.

Corrections

  • A previous version of this story said the mine opened almost a decade ago. That information was incorrect. De Beers began operations at Snap Lake in 2008. That story also said if De Beers is not in compliance with its water license, the only solution is to shut down the mine. De Beers says that is, in fact, its contingency plan, but the company is working on a number of other solutions.
    Jun 07, 2014 11:34 AM CT