Dust from the Giant Mine's tailings ponds often creates clouds outside Yellowknife. (CBC)Dust blowing off toxic waste ponds at the defunct Giant Mine near Yellowknife has a nearby aboriginal leader concerned and calling on at least one level of government to have the ponds covered up for good.

About 16 million tonnes of tailings — the powdered rock left over from half a century of gold refining at Giant Mine — are stored in tailings ponds above ground at the mine site.

Dust from the pond often creates a cloud over the site, located about five kilometres outside Yellowknife.

The cloud appeared to be so thick one time last year that Chief Fred Sangris of the Yellowknives Dene First Nation in Dettah said he thought a forest fire had started.

"We had a 60-, 70-kilometre wind that time, and it was going right over my community," Sangris told CBC News.

"You could see it — a big red [cloud] right over this community," added Sangris, who is urging at least one level of government to have the tailing ponds covered for good.

Federal authorities in charge of cleaning up the mine say they know there are higher-than-acceptable levels of arsenic in that dust, but they have been trying to keep the dust to a minimum.

"For the last several years, we've been applying a product called Soil-Sement. It's a polymer which helps to bind the surface of the tailings and helps to prevent dusting," project manager Bill Mitchell told CBC News.

But the solution is only effective to a point, Mitchell said: it has to be applied every year, and some areas of the tailings ponds are too inaccessible to the tanker that sprays on the solution.

Giant Mine remediation manager Bill Mitchell said crews apply a solution to tailings ponds to try to prevent dust from blowing away. (CBC)As well, there is a time every spring when the ponds are too damp to apply it, but the surface tailings are dry enough to blow away.

Some have raised concern about dust particles that can lodge into people's lungs, possibly triggering asthma attacks and other lung problems.

N.W.T. chief medical officer Andre Corriveau said people working around the tailings ponds should have protection against the dust. Otherwise, the dust poses little risk to others.

"From a population health perspective here in Yellowknife, those ponds are a sufficient distance away from Yellowknife that it's not affecting a lot of people," Corriveau said.

The Giant Mine produced more than seven million ounces of gold from 1948 until it closed in 1999.

The federal Indian and Northern Affairs Department has since been responsible for cleaning up the mine site, a task that includes dealing with 237,000 tonnes of poisonous arsenic trioxide dust — another byproduct of the gold refining process — currently stored in underground chambers.

Much of the department's proposed $300-million Giant Mine remediation plan has focused on how to contain the arsenic trioxide, with the plan proposing to freeze the toxic dust in vaults beneath the mine.

As for the tailings ponds, federal officials say they cannot cover the ponds permanently — a task that's also part of the cleanup process — until regulators approve the remediation plan. That regulatory process is expected to take several years.

But Sangris, whose First Nation has long been calling for the tailings ponds to be cleaned up for good, said he believes Ottawa is hoping that either the territorial government or the City of Yellowknife will grow impatient and cover the ponds sooner.