The consequences for Grassy Narrows, however, were devastating. Those who suffered most were the First Nations members who followed traditional hunting lifestyles or worked as tour guides. Many developed Minamata disease, a neurological disorder caused by mercury poisoning. Its effects are similar to the motor-neurone disease amyotrophic lateral sclerosis (ALS), and include numbness in the limbs, difficulty walking, slurred speech, impaired hearing and in some cases paralysis and death.

Life on Grassy Narrows began to fall apart. Within five years of the closure of the fishery, unemployment in Grassy Narrows rose from 5% to over 90% (it rests near 40% today). The welfare rolls increased from $9,000 to $140,000. Drinking and violence – partly caused by despair, partly thought to be a side-effect of mercury poisoning – overwhelmed the reserve, and spread into nearby towns like Kenora, a city of 15,000 that developed one of the highest violent crime rates in the country.

The government did not deal with the social or health repercussions. Instead, it made a few token economic gestures: it distributed non-contaminated fish to Grassy Narrows residents, gave out $63,302 in forgivable loans to fishers and subsidised non-Native-owned tourist lodges to help them hire people from Grassy Narrows.

Little was done to help those who had fallen sick due to mercury contamination.

Nothing was done to clean up the river.

The abuse of First Nations people and the destruction of their communities was nothing new to Canada, but the disaster happened to coincide with something that was.

This was the so-called White Paper on First Nations Rights, a proposal by the government of Pierre Trudeau. The paper proposed to eliminate “Indian” status, abolish the reserve system and convert reserve land into private property.

It was hugely controversial. First Nations people roundly rejected the White Paper as a plan to extinguish all indigenous rights, and to encourage full assimilation. In July of 1970, three months after the Grassy Narrows spill, the government was forced to withdraw it.

Although the White Paper was scrapped, it was not forgotten in Grassy Narrows. The people had seen firsthand how precarious their rights were – including their treaty right to fish and hunt on their land. And the fight against the White Paper also brought together a network of young activists.

Four years after the Grassy Narrows spill was uncovered, these activists took up arms against Canada: they seized Anicinabe park in Kenora, the first time in generations that First Nations people in Canada had attempted such radical action.

They called themselves the Warrior Society.

“The lawyers, the judges, the MPs, the politicians, the police, you name it – they weren’t listening to nobody,” says Tommy Keesick.

I met with Keesick, now a young-looking 72 with greying, pulled-back hair, at a Chinese restaurant in Kenora, along with six other elderly members of the Warrior Society: Lorraine Major, Harry Greene, Rosabelle Major, Richard Greene, Lynn Skeen and Nancy Morrison.

Each person at the table joined in the park occupation for their own individual reasons. For Nancy Morrison, it was losing her home.

“I went to residential school – the horror stories everybody knows,” she says. “All of a sudden I was 17 years old, and I went back to my reserve. And when I came back, there was absolutely nothing. No tents or anything left.” Everyone had been forcibly relocated.

The mercury crisis “really inspired us”, says Richard Greene. “We had to do more serious things to make our grievances known.”

In the 1970s, Lorraine Major reminds me, indigenous people had “no control of any programs, institutions, education – we absolutely had no control over anything”.

Major had worked with the American Indian Movement (Aim) in Minnesota, where it had been founded a decade before. Aim was all over the American news throughout the early 1970s: its activists had occupied Alcatraz Island in 1969, seized a replica of the Mayflower in Boston Harbor and gathered in force at Mt Rushmore in 1970. They had also burned down a courthouse and started a standoff with federal officers.

By 1974, shootouts and federal action had led to dozens of injuries, and more than 1,200 Aim activists being detained. But it was in Canada where Aim would find a new way of being, one that set a model for indigenous resistance that is still in use today.

In a 1974 interview, Louie Cameron, another key collaborator, explained why they decided to translate Aim into the Canadian context in the first place – and why they deliberately chose the term Warrior Society, instead of Aim.

“In Kenora, they put us down if we say we believe in Aim,” he said. “So for the purpose of our own people here, we titled the movement – which is the same movement as the American Indian Movement across the continent – the Ojibway Warriors Society.” He continued: “Myself, it doesn’t matter what title you put on it. It’s the movement that’s important.”

The Warrior Society was different from Aim, however. Aim was an urban organization, made up of members from many different indigenous nations. But the Ojibway Warrior Society was based in a single community.

The difference is significant. Connection to a community – especially one where respect for elders runs deep – prevents passions and excesses from running wild, and keeps members accountable to their neighbours. It became the model for a particularly long-lived form of activism.

In 1975, Keesick was invited to Minamata,Japan, to meet the victims of the disease where it was first identified and get tested for mercury poisoning.

“I’m afraid,” he told the Toronto Star on his return to Canada. “All the crippled people I saw.”

Japanese scientists visited Grassy Narrows, and in 1975 declared the presence of Minamata disease. Emboldened by the diagnosis, the Grassy Narrows First Nation launched a lawsuit in 1977 against Reed Paper seeking compensation for the damage to people and the environment. This lawsuit was settled in 1985, with the provincial government taking on all future liability for the mercury spill, in exchange for Reed Paper company paying $17.4m into a compensation fund for victims.

Other suits have since been filed in defence of their treaty rights, including against clearcut logging that they say could exacerbate the mercury problem. Keewatin is a plaintiff in that suit. “The government doesn’t listen to anybody,” he says. “It only listens to the court.”

The activism continued to snowball. A messy Mohawk civil conflict erupted in the shadow of another mercury spill by the Reed Paper company – this time in Akwesasne, in the region where Ontario, Quebec and New York meet. It was there in 1980 that images of an armed First Nations Warrior Society re-entered the news cycle.

With increasing agitation on reserve for changes, and with the image of armed Warriors not far from their minds, the Ontario and Canadian governments formed a joint steering committeeto look at the environmental problems in the region. In 1984, the steering committee recommended cleaning up an 80km stretch of the Wabigoon river system. Otherwise, the committee said, it would take at least 70 years for the fish to once again be safe to eat.

The cleanup would cost $13.5 to $20.4m in 1981 dollars, to be borne by the provincial government; in response, the Ontario government commissioned a report of its own, which recommended against remediation, opting instead to see how natural processes would reduce mercury pollution.

By then, Grassy Narrows had hit a low point. “There were homicide cases in the community, suicides, overdose of pills,” Fobister told the CBC in 1987. “There was a lot of violence … parties were just about all over the reserve. You couldn’t find a sober person.”

Fobister, who was exhibiting the first signs of Minamata disease, became chief and formed groups to stop the violence, even if it meant “getting physical” with enraged mobs of alcoholics.

“I said on national television I was willing to put my life on the line to make everything happen and to bring justice to my people. And I did it!” he says today with sudden force. “I went on a hunger strike. Because of my health, it kind of got the government’s attention. They saw that I was a very high-risk case and they didn’t want to be responsible. Something did happen then.”

He only ended his hunger strike when Ontario’s minister for indigenous affairs, David Zimmer, visited his bedside and committed to build the care facility.

After speaking with Fobister, I contacted the ministry of indigenous affairs to find out the status of the new healthcare centre. They explained to me that the care facility is currently at the study stage.

While it’s doubtful that the health centre will be built in time to benefit elders such as Fobister, his hunger strike helped put Grassy Narrows back in the news, and directed the media spotlight to a new generation of activists. Among those is Judy Da Silva, the reserve’s environmental officer, widely acknowledged as Grassy Narrows’s new leader on the mercury issue.

I met Da Silva in Winnipeg, where she had just returned from a week of meetings and media events in Toronto to publicize the most comprehensive study yet on the poisoning of her community. Her report is one of several produced by Grassy Narrows First Nation in recent years, showing younger people still being afflicted with mercury poisoning and continuing to press for a clean-up of the river system.

This last report was one of the catalysts that caused Ontario’s Liberal government to promise in 2017 that it would commit $85m to clean up the Wabigoon. The new conservative premier, Doug Ford, has reaffirmed the promise to clean up the river “as quickly as possible”. On 28 September, the Ford government’s minister responsible for indigenous affairs, Greg Rickford, visited Grassy Narrows to announce a retroactive increase in disability funding for victims of mercury poisoning

Promises are taken with a grain of salt in Grassy Narrows, where little is achieved without a fight. “I’m not optimistic,” Fobister says. “I’m frail, I’m sick, nobody has to listen to me. And I have no power against money – once money starts getting thrown around, oh my goodness, there goes our momentum, there goes our rights.”

A side-effect of Minamata disease is that there are few elders like Fobister or Keewatin left. “One of the sad findings [of the report is] we have a lower elder population,” Da Silva says. “It shows that our people don’t grow to be elders or that the elders that survive are very ill.”

But in the 48 years since the mercury crisis began, two generations have come of age. Because of the toxic effects of their poisoned waterways and the social dysfunction that followed, these generations didn’t learn fishing, hunting or trapping. Instead, they were raised in a culture of protest and resistance.

These societies spread well beyond the Ojibway – to Oka and to Gustafsen Lake and to the Trans Mountain pipeline disputes. The model even moved into the US: at the protests against the Dakota Access pipeline, protesters came together in the Red Warrior Camp. They blocked roads and occupied territory – but now armed with cameras and a worldwide network of supporters.

As a third generation is set to come of age, that culture of resistance and the warrior society model seems firmly entrenched. On my visit to Grassy Narrows, I’m shadowed by a local student named Nora Sneaky. To an outsider she seems very shy – but appearances are deceiving. She and her friends have been at the head of recent protests on the mercury issue, including a recent demonstration at a nearby industrial facility as part of international water day.

In 2016, Sneaky and her compatriots at the youth complex made a music video, Home to Me, to show pride in Grassy Narrows and tell others that their home is more than the site of a mercury disaster. In it they sing: “We want peace in the land, can’t go back to battles” – although for them, avoiding battles doesn’t seem to be an option.

Greene explains why he encourages youth like Nora to fight back. It’s about more than just the issue being protested, he says. “You give life to identity when people stand up for who they are.”

“A long time ago we had what we called the kaagiikwaywin. It meant the elders taught the minute the child was born,” Keesick tells me. “This is part of the stuff that we were talking about when we called ourselves the Ojibway Warriors Society. We were going to deal with everything from that till now and into the future, to make sure that our children would not take any more of this shit.”

• Steve Fobister Bah died in a Kenora hospital shortly before the publication of this article. He had previously been relocated to a health centre in Thunder Bay, 600km from his home. Grassy Narrows continues to wait for a care facility for Minamata disease