The Government of the Northwest Territories has added to its list of lakes with elevated levels of arsenic.Recent environmental data show that Niven, Range and Fiddler lakes have arsenic levels above Health Canada’s drinking water guidelines. Consequently, the territory’s chief public health officer is warning people not to drink water from these lakes.
The three lakes are, however, safe for swimming, fishing and other recreational activities, Andre Corriveau said Friday.
Corriveau said Niven, Range and Fiddler lakes had not previously been tested for arsenic.
Health Canada sets the limit for arsenic in drinking water at 10 parts per billion (0.010 milligrams per litre), based on a lifetime of exposure.
Water with a concentration greater than that is not considered acceptable for drinking.
The amount of arsenic in Niven, Range and Fiddler lakes “wouldn’t be a concern for one gulp or even if you made tea once in a while,” said Corriveau, but drinking from them should be avoided nonetheless.
It’s ill-advised to drink untreated water from any lake, he added.
Arsenic warning signs were installed around Frame, Jackfish, Rat and Kam lakes last fall.
These lakes have arsenic concentrations between 52 and 499.9 parts per billion, meaning people should avoid swimming, fishing and drinking from these lakes, and should not harvest plants, berries or mushrooms nearby.
Corriveau said there is no plan to put up warning signs at Niven, Range and Fiddler lakes, which have arsenic levels of 10 to 51.9 parts per billion.
Long and Grace lakes are also in this range.
In total, six lakes were added to the GNWT’s list of water bodies with elevated levels of arsenic.
Three of these are unnamed lakes and were found to have arsenic levels above 52 parts per billion, meaning they are not considered safe for recreational activity. These lakes are more like ponds, said Corriveau, and are not easily accessible to people.
The government also expanded its arsenic-impacted “area of interest,” to just north of Long Lake.
The area of interest includes land and water that is close to a mine, next to a body of water with higher arsenic levels and where elevated levels of arsenic were found in the soil.
“It’s really a quite minor change,” said Corriveau of the lands and lakes added to the government’s
area of interest.
He said the area was expanded based on new data, including the results from the human health and ecological risk assessment that was delivered to the federal government in January. That study examined the risks to people, wildlife and plants from exposure to contaminants in the environment as a result of past gold mining at Giant Mine.