The Kanien'kehá:ka (Mohawk) Nation at Kahnawake (Longhouse) is not mincing words when accusing the neighbouring municipality of Chateauguay of not properly informing the community on Montreal's South Shore when it detected a diesel oil spill that leached into a river on the territory.

"We consider this an act of aggression against the Kanien'kehá:ka of Kahnawà:ke," it said in a press release Thursday.

The traditional Indigenous body in Kahnawake accuses the municipal government of not properly cleaning up the mess and knowing about the Feb. 1 spill close to its boundary just over a week later.

"It also appears that Chateauguay's cleanup efforts only went as far the boundary line of Kahnawà:ke, leading us to believe that Chateauguay deliberately attempted to hide evidence of the spill," reads the Longhouse news release.

The Kanien'kehá:ka (Mohawk) Nation at Kahnawake is a separate entity from the elected Mohawk Council of Kahnawake (MCK). The Longhouse will hand-deliver a message to the mayor and municipal council on Friday.

Quebec Premier Francois Legault will also be in the area, saying he will meet with MCK Grand Chief Kahsennenhawe Sky-Deer in Chateauguay.

The MCK, for its part, said on Feb. 12 that the situation is under assessment, "as mitigation efforts continue," and added that the federal and provincial environment ministries were informed.

The MCK says water samples were taken and showed unsafe levels of petroleum hydrocarbons, and that Environment Canada (ECCC) is conducting additional testing.

In a news release, Chateauguay Mayor Eric Allard called it: "A shocking and terrible situation for the people and the environment affected."

"This situation is shocking and terrible both for our residents and those of Kahnawake, and for the environment," he said. "Protecting the environment is crucial and essential in the face of climate change and is one of our priorities in Châteauguay. It's intolerable that such a situation should have arisen for a reason that has yet to be explained."

The Chateauguay news release says the spill was on private property and "appears to be an accidental or criminal spill."

Chateauguay claims the spill came from the building on the corner of Ford Boulevard and Industriel Boulevard that houses a number of businesses, including a scrap metal recycling shop, an electronics store and a demolition business.

Authorities say a Kahnawake resident noticed contamination on Feb. 9 and that it was affecting Suzanne Creek, a small waterway that crosses the two territories.

Chateauguay claims it was notified about the spill on Feb. 11, a day after Environment and Climate Change Canada and the provincial environment ministry were notified.

Fuel spill in Chateauguay and Kahnawake

The city admits, however, that its emergency services were notified by the owner on Feb. 1 that they wanted the diesel tanker towed away.

"Unfortunately, the owner of the tanker died last weekend, complicating the investigation," the city said in a news release. "To date, the ditch has been cleaned up and containment and prevention measures are in place. The situation is contained and under control."

Allard said Chateauguay is working with the federal and provincial authorities as well as the Mohawk Council to ensure whoever is responsible for the spill assumes all consequences and costs.

"Any spillage of toxic products into the environment is a horror and a tragedy for the public and the environment," said Allard.

The Longhouse is accusing the municipality of continuing a history of "systematic environmental racism towards Onkwehón:we (Indigenous) peoples."

"Kahnawà:ke has been plagued with a concentration of industrial pollution from surrounding cities and municipalities," the release reads. "From expropriating our land to build bridges, power lines, highways, railways, and an international seaway through our tiny community, to aiming industrial waste towards our rivers and wetlands through their storm drains – it is clear that Chateauguay, Quebec and Canada consider Onkwehón:we people expendable in their pursuant of economic development."