A legal challenge filed in Manitoba's Court of Queen's Bench could cost the federal government billions, if it is proven the government has violated the Charter rights of a large class of First Nations people for decades by failing to provide them with safe drinking water.

A proposed class-action lawsuit was filed on Nov. 20 by Tataskweyak Cree Nation Chief Doreen Spence on her own behalf and on behalf of her northern Manitoba First Nation. The suit alleges the First Nation has spent decades without access to clean drinking water and seeks damages.

Tataskweyak has been under an official long-term boil water advisory since 2017.

The lawsuit alleges that the federal government received consistent advice for decades that it was depriving First Nations of adequate access to clean drinking water, but did not act.

"Although Canada was advised of the devastating human consequences of these failures, its response to this human catastrophe was — and continues to be — a toxic mixture of inertia and incompetence," the lawsuit says.

"It conducted its affairs with wanton and callous disregard for [the] interests, safety and well-being" of people living under the advisories, the suit says.

If it is certified as a class action, the suit will aim to bring together a class made up of any member of a band whose land was subject to a water advisory that lasted at least one year, at any point from Nov. 8, 1995, until the present.

'A long-standing problem'

Michael Rosenberg, a partner at McCarthy Tétrault and the lead lawyer in the suit, says it's not clear yet how many individuals would make up the class.

Beyond the 57 reserves currently under long-term water advisories, there are many examples of communities, such as Pauingassi or Hollow Water First Nation, that were under advisories for years before they were lifted.

"It would be a significant number. This is a long-standing problem," Rosenberg said.

Tataskweyak Cree Nation, about 700 kilometres north of Winnipeg, is one of two First Nations in Manitoba currently under long-term boil water advisories, along with Wuskwi Sipihk First Nation in northwestern Manitoba.

Tataskweyak "was a community that wanted to take a leadership role," as the lead plaintiff in the suit, Rosenberg said.

"In terms of the geography of this crisis, there has been a significant instance of long-term drinking water advisories in Manitoba."

Prime Minster Justin Trudeau, seen here in a 2016 file photo, promised in 2015 that all drinking water advisories on First Nations would be lifted by 2021. (Adrees Latif/Reuters)

A spokesperson for Indigenous Services Canada said the federal government is aware of the suit and is seeking legal advice.

The spokesperson also noted the government has committed more than $2 billion toward on-reserve water and wastewater infrastructure since 2016.

Promise to have advisories lifted by 2021

The federal Liberals ran on a campaign promise in 2015 to have all boil-water advisories lifted by March 2021.

According to the federal government's water advisory tracker, Tataskweyak is scheduled to be one of the last First Nations to have its advisory lifted, with a completion date slated for March 2021.

The lawsuit alleges Tataskweyak Cree Nation has been denied adequate access to drinking water since the early 1950s, as upstream development and agricultural use degraded the water quality in Split Lake — the source of the First Nation's drinking water.

That drinking water source is so contaminated it is no longer safe to swim in Split Lake, and warning signs now adorn the shores of the 46-kilometre long lake, the lawsuit says.

"Exposure to the water has caused members of Tataskweyak Cree Nation to contract illness of increasing severity with increasing frequency," the suit says.

"Those who are exposed to the lake water, especially children, often develop rashes or sores and require medical care."

Throughout the years, sewage from the city of Thompson and other upstream communities has entered into Split Lake. This has caused elevated E. coli levels in the water, the suit says, and blue-green algae contamination has devastated the fishing industry.

"Fishermen regularly catch fish covered with grotesque lesions," it says.

An attempt to build an adequate water treatment plant for Tataskweyak failed, because the plant was not built with enough capacity, according to the court document.

More than $2B in damages

In addition to seeing the federal government held liable for the damages caused by the unsafe drinking water, the suit also seeks to force the government to immediately construct, or approve and fund the construction of, appropriate water systems for the class members.

The feds would also be on the hook for $1 billion in damages for the breaches of the Charter rights, $1 billion for negligence of its fiduciary duty and $100 million in punitive damages.

Rosenberg says the next step will be bringing a motion before the court to get the class action certified.

"My hope is that Canada will redouble its efforts in the interim to provide measures that address the ongoing suffering of class members — particularly those who are unable to access clean drinking water," he said.