Federal officials are refusing to talk about the recent flooding of a tailings pond at the defunct Giant Mine near Yellowknife, raising concerns about mining waste potentially contaminating a nearby creek and lake.

The tailings area, which holds toxic byproducts from decades of gold mining, was flooded on May 14 when an ice dam formed on nearby Baker Creek.

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Giant Mine, located just outside Yellowknife, produced more than seven million ounces of gold from 1948 until it closed in 1999. ((Donna Lee/CBC))

The dammed creek flooded its banks and washed over the tailings. The water seeped through the waste and eventually flowed back into the creek, which empties into Great Slave Lake a few kilometres away.

In the days after the flood, officials from four federal departments and an engineering firm were at the tailings pond to assess the problem. Pumps and generators were set up to draw creek water away from the tailings, and water samples were taken daily.

But so far, none of the departments involved — the Aboriginal Affairs and Northern Development Department, the Department of Fisheries and Oceans, Environment Canada, and The Department of Public Works and Government Services — would talk publicly about what the water tests show.

"I think there must be a reason because if there were minimal concerns, they would have released the results of the water samples," Chief Edward Sangris of the Yellowknives Dene First Nation in Dettah, N.W.T., told CBC News on Wednesday.

Conflicting interests

Sangris said there is a conflict of interest within the Aboriginal Affairs and Northern Development Department, which is involved in cleaning up the Giant mine site, but is also responsible for enforcing the same environmental rules it must obey.

The minister responsible for the department, which was known as Indian and Northern Affairs Canada (INAC) until last week, is also responsible for approving the water licence and cleanup plan for the former mine.

"When the Giant [remediation] thing went to an environmental assessment, we always said that we need an independent monitoring system," Sangris said.

"Right now, as it's set up, the permits [are] issued to INAC, and they're the one that issued the permits. So who's monitoring the regulators?"

Yellowknife environmentalist Kevin O'Reilly, who has been an intervenor in the environmental assessment of the Giant Mine cleanup plan, agreed that an independent monitor is needed.

"That's just way too many roles and responsibilities within one department, and I think what will drive this is keeping the costs to a minimum," he said.

"Yes, they say that human health and the environment is important, but the bottom line is going to be how much this costs and trying to minimize those costs."

Since the federal government has been silent about its water test results, it is impossible to say what effect the flooded tailings pond will have on water quality in Baker Creek and Great Slave Lake.

It also remains to be seen what effect the flooding will have on Arctic grayling that are expected to swim through Baker Lake soon as part of their spawning run.