Arsenic concerns loom as Yellowknife's drinking water debate begins

Yellowknife city council has begun looking at the most controversial issue it will likely face this term:changing the city's drinking water supply.

At a meeting on Monday, councillors ordered city staff to update a 2011 report on the pros and cons of drawing water from Yellowknife Bay, instead of continuing to pipe it in from the Yellowknife River.

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Though it was a small first step, councillors didn't make it without hearing some opposition to even considering drawing water from the Bay.

"I honestly don't think that there's anything more important than putting that pipe back in place," said Yellowknife resident Georges Erasmus. "Anything else is really reckless."

Erasmus is a former head of the Dene Nation and AFN and, later,co-chair of the Royal Commission on Aboriginal Peoples.

Since 1968, the city's drinking water has come from the Yellowknife River, through an eight kilometreunderwater pipe. The federal government made the move because city residents were worried that the city's two gold mines had contaminated the Yellowknife Bay. The city had drawn its water from the bay for 20 years prior to that.

Erasmus said arsenic is still leaching from the mines into the bay. He also reminded councillors there is no plan to address the spectre of the 237,000 tonnes of highly toxic arsenic trioxide dust stored underground at Giant Mine, within a kilometreof the bay.

Council 'has a tough job': Mayor

Yellowknife's mayor says the city should rely on science when making their decision.

"I think council has a tough job ahead of them," said Mark Heyck. "We have to distinguish public concern and public perception from the science that's been done over the last several years."

The 2011 report notes that arsenic concentrations in the bay are well below the 10 parts per billion limit set for drinking water. It also notes that arsenic levels in the sediment of the lake bottom are tens of times higher than the drinking water limit.

The aging underwater pipe is due to be replace by 2020. City council is considering switching to Yellowknife Bayto save money, as replacing the pipe is estimated to cost $20 million. Drawing water from the bay and retrofitting the water treatment plant with arsenic filters is estimated to cost significantly less, at$5 million.

The 2011 report looked at a scenario where a tailings pond at Giant Mine breaches and dumps arsenic into Baker Creek. It's not clear if the "scenario" is based on something that actually happened in 2011, whena tailings pond flooded and arsenic was flushed down the creek and into the bay.

The scenario suggests thatif arsenic concentrations increased to 20,000 parts per billionat the mouth of Baker Creek, scientific modelling indicates it would be diluted to 100 parts per billionby the time it reaches the drinking water intake, well within the capacity of arsenic filters to handle.