The N.W.T. government has approved a change that will allow the level of total dissolved solids (TDS), including mineral salts, in Snap Lake to be almost triple what was allowed only five months ago.

The change, which was opposed by aboriginal groups, comes in an amended water licence for De Beers Canada's Snap Lake diamond mine. Environment Minister Michael Miltenberger approved the amended licence on Sept. 10.

Michael Miltenberger

N.W.T. environment minister Michael Miltenberger has approved a change to the water licence for De Beers' Snap Lake diamond mine that will allow the limit for total dissolved solids (including mineral salts) in Snape Lake to be nearly tripled. (CBC)

Now, the total allowable level of TDS in Snap Lake is 1,000 milligrams per litre, compared to 350 milligrams per litre back in April.  

De Beers had asked for the change because it's encountering a higher than expected amount of TDS-rich groundwater at its Snap Lake mine, located 220 kilometres northeast of Yellowknife.

The company pumps, treats and releases that water into Snap Lake, but it has also stored some of that water underground, at a cost of at least $20 million, to avoid going over the previous TDS limit.

The result has been that De Beers can't mine everywhere it wants to at its Snap Lake operation.

"The amended water licence is one of the key steps toward to the long-term sustainable operation of Snap Lake mine," says Tom Ormsby, De Beers' director external and corporate affairs in Canada. 

Miltenberger's approval should now allay fears about the 800-person mine closing early, something De Beers had pointed to as a possibility if the TDS limit was not raised to the level the company sought.

For drinking water, Health Canada has set an esthetic objective of 250 milligrams per litre for chloride, one of the components that make up mineral salts. Above that level, the taste of the water may become "undesirable."  

Employees at the Snap Lake mine get their drinking water from Snap Lake.  

'This is a disappointing decision'

Aboriginal groups such as the Lutsel K'e Dene First Nation and the Yellowknives Dene First Nation had opposed raising the limit because, they said, traditional users of the land near the lake might think twice about drinking the water due to its changed taste and perceptions about health risks.

"This is a disappointing decision," said Peter Unger, the manager of wildlife, lands and environment for the Lutsel K'e Dene First Nation.

"It is always a disappointment when economic interests win out over community concerns, including those of Lutsel K'e, Dettah and N'Dilo," Unger said.

"What is more concerning is that Minister Miltenberger's own staff opposed this decision based on their extensive expertise. It says a lot when a mine can change the conditions imposed on them simply based on the threat of closure."