The Globe and Mail:

Almost six million litres of water with more than twice the legal limit of suspended solids was released from a pond at the Fort Hills oil sands project into the Athabasca River watershed over the weekend, the second large spill in the northern Alberta region this year.

The water came from a sedimentation pond. A common part of oil sands projects, the ponds capture surface water runoff and let it settle before the water is released according to Alberta Energy Regulator limits. Those limits allow total suspended solids of 50 milligrams a litre in discharge water.

The pond at Suncor Energy’s SU-T -0.10%decrease Fort Hills collects silty water and discharges it into Fort Creek, 800 metres upstream of the Athabasca River.

On Sunday, water from the pond with suspended solids at more than twice the legal limit – 116 milligrams – was released from the oil sands project into the Athabasca River, according to the regulator.

Suncor stopped the discharge system and is working to understand how the incident happened, the AER said.

The Calgary-based company told the AER the system will remain down until suspended solids fall within regulatory limits, the AER said. It has also taken water quality samples and will share the results when they’re available.

Suncor told The Globe and Mail it has notified communities and local government about the spill.

The AER said it is “continuing to work with Suncor and will be monitoring the situation closely” and is assessing the incident to determine if it will be investigated.

The Northwest Territories, however, was not notified of the incident. That’s despite a transboundary water agreement under which the two jurisdictions are supposed to inform one another in case of any event that might affect an aquatic ecosystem on the other side of the boundary.

NWT Minister of Environment and Climate Change Shane Thompson said in an e-mail he is “deeply concerned by this lack of information sharing and notification” by Alberta.

“These waters ultimately flow into the Northwest Territories and are critically important for subsistence, cultural, and other purposes by Indigenous peoples and other NWT residents,” he said.

“Unfortunately, this is yet another instance of the Alberta government not meeting their commitments under our bilateral water management agreement. It comes within a month of us finding out about the spills at Imperial’s Kearl Lake site, an incident that Alberta and the NWT are currently in dispute resolution over within the transboundary agreement.”

Mr. Thompson said he would raise the issue when he meets with his Alberta counterpart Sonya Savage on Wednesday. Alberta’s Environment Ministry did not return a request for comment.

Federal Environment Minister Steven Guilbeault said Tuesday he has “asked urgently Environment Canada officials to look into it.” Environment and Climate Change Canada told The Globe it was notified of the spill on April 16, and that enforcement officers are assessing the situation.

It’s the second major incident this year in which more than five million litres of water from an oil sands site in northern Alberta has spilled into the environment.

On Jan. 31, 5.3 million litres of industrial waste water laced with pollutants spilled from a drainage pond at the Kearl oil sands site. Imperial Oil Resources Ltd. IMO-T +0.24%increase has attributed the incident to a combination of equipment problems and process failures.

A tailings pond leaked earlier at the same site, which is still going on. Imperial Oil still does not know how much water tainted with dangerous levels of arsenic, dissolved metals and hydrocarbons has seeped from the site since the leak was discovered in May.

The company and the AER have come under fire from Indigenous communities downstream from the oil sands project. The communities were not informed about the leak for months, until after the large drainage pond spill.

The House of Commons environment committee is this week holding two meetings about leaks and spills from the oil sands.

Representatives from six First Nation and Métis communities downstream from Kearl appeared before the committee on Monday to detail how the leak has affectedthe environment, their way of life, and their relationship with both the AER and Imperial Oil.

Imperial Oil chief executive officer Brad Corson will appear this week, and AER CEO Laurie Pushor is scheduled for next week.

In response to the outcry over the Kearl incidents, Ottawa will create a working group to monitor notification and monitoring in the oil sands. It is set to include representatives from federal and provincial governments, Indigenous nations, the Northwest Territories government and oil sands companies.

Mr. Guilbeault sent letters to First Nations and Métis communities on Monday, and said the group’s mandate would be established with their input over the next two months.

EMMA GRANEY, ENERGY REPORTER