Imperial Oil is investigating to see if a spill from a produced water line at the Norman Wells, N.W.T., operation has entered into the Mackenzie River.
The spill was reported to the N.W.T. Department of Environment and Natural Resources on Wednesday and according to the federal regulator occurred between Bear and Goose Island.
Produced water is treated water that is pumped to the surface during oil recovery and then reused. According to Transport Canada, produced water can contain contaminants from oil extraction, but it varies with how much it contains.
The company estimates the quantity of the spill is 55 cubic metres (55,000 litres).
Lisa Schmidt, a spokesperson for Imperial Oil, said in an email the company is investigating the situation.
"The line was quickly shut down. We currently estimate that approximately 55 cubic metres may have been released. We are still investigating whether produced water entered the Mackenzie River," she wrote.
Schmidt said Imperial Oil is monitoring the water quality and there are no indications there is a risk to public health or wildlife.
"We have notified regulators and have shared this information with local communities."
No details have been provided on what caused the spill.
Lisa LeBel, a spokesperson for Canada Energy Regulator, said in an email the agency "requested additional information from Imperial on the concentrations of chloride and hydrocarbons in the released fluid, an assessment of any potential impacts of the release as well as the actions that will be taken to repair the leak and prevent reoccurrence."
Norman Wells Mayor Frank Pope said the leak was reported to him and that Imperial Oil has staff responding to the situation.
Downriver in Fort Good Hope, Edwin Erutse, president of the Yamoga Land Corporation, said he has received a call from a concerned resident on the spill and plans to followup to find out more.
Erutse said the spill comes during a busy fishing time in the community.
"People have nets and that out on the river, so I want to make sure that these concerns don't go unaddressed," he said.