Metals in Slave and Hay rivers shouldn’t hurt fish, GNWT says

The NWT government says higher-than-normal concentrations of metals in the Hay and Slave rivers in 2020 shouldn’t pose a health risk for aquatic life.

In September, the territory said the summer’s prolonged high water levels had led to more sediment in the rivers than usual. Water quality monitoring found metals associated with silt and clay particles – including total arsenic, barium, cesium, chromium, iron, and zinc – were also in more abundant supply. 

On Friday, the territory said concentrations of those metals had returned to normal levels by August and weren’t expected to harm bugs or fish. 


“Healthy water is of the utmost importance to the NWT and its residents,” environment minister Shane Thompson said in a statement.

“The data and information we have gathered suggest that impacts to fish are not expected.”

A screenshot of Great Slave Lake on August 20, 2020 from Nasa's Worldview program, which provides near real-time satellite imagery
A screenshot of Great Slave Lake on August 20, 2020 from Nasa’s Worldview program. Brown silt plumes can be seen across the centre of the lake.

The government said the higher levels of sediment in the water were the result of heavy rains and run-off last spring and summer.

According to the territory’s numbers, the Slave River’s water flow in July 2020 was 50 percent higher than is usually the case – some 7.5 million litres of water rushed by each second. 

Sediment in the Slave and Hay rivers was responsible for the large, brown plume in Great Slave Lake that summer – and also triggered a protracted series of boil-water advisories in Hay River.


Water summit planned this summer

Water quality monitoring upstream of the NWT in Alberta was suspended for months last year, a decision attributed to the impact of the Covid-19 pandemic.

Friday’s NWT government news release made no mention of any adverse impact from the lack of monitoring in the neighbouring province, and made no suggestion of any concern related to Alberta’s oilsands.

The Dene Nation is planning a water summit later this year to consider repeatedly voiced concerns about the containment of toxic oil industry waste and the possible downstream impact on First Nations in and around the NWT.


Last month, Dene National Chief Norman Yakeleya told Cabin Radio he would invite federal environment minister Jonathan Wilkinson, among others, to attend that summit. No firm date has been set, though Yakeleya hopes it will take place between June and August.

“We need to know that there is going to be a Dene-led increase in monitoring stations,” said Yakeleya in December.

“We need to know the strength of the transboundary agreements,” he added, referring to the agreements between the NWT and its neighbours that govern how governments together manage water quality.

“The bottom line is that we want to continue to have safe water, good water in the North. If we don’t do anything, there are going to be severe consequences.”

Ollie Williams contributed reporting.