The chief of a small Northern Ontario First Nation whose people are being poisoned by mercury from a defunct paper mill is urging Prime Minister Justin Trudeau to engage the federal government in the cleanup of the river that is the source of the community’s fish.

Simon Fobister, the Chief of the Grassy Narrows First Nation, has written twice to Mr. Trudeau – in May and in September – and Mr. Fobister’s predecessor, Roger Fobister, wrote to the Prime Minister in March. All of the letters told Mr. Trudeau: “We invite you to visit our community to announce alongside us that the mercury in our river system, our source of life, will finally be cleaned up.”

The chief says he has received no response to those invitations, though the Prime Minister’s Office acknowledged to The Globe and Mail that it had received them. A spokeswoman for Mr. Trudeau pointed out that a representative of the Indigenous Affairs department visited the community in June along with provincial ministers.

Many First Nations in Canada are coping with the negative environmental consequences of development on or near their territories, but few have endured hardships like those suffered in Grassy Narrows, where 90 per cent of residents are showing signs of mercury poisoning.

The current chief said in his most recent letter that Mr. Trudeau’s silence on the matter of Grassy Narrows is troubling.

“You have made important election promises to repair Canada’s relationship with First Nations and to right many of the wrongs that have been done to First Nations people,” wrote Mr. Fobister. “We consider those promises to be sacred and we are hopeful that you will honour your word.”

Responsibility for the mercury problems straddles provincial and federal jurisdictions and, so far, the province of Ontario has borne much of the blame for the fact that the contamination has persisted in the Wabigoon River for six decades. But David Sone of Earthroots, a conservation advocacy group, says there are at least three reasons for the federal government to get involved.

“There is at least still some [federal] responsibility for fisheries where they are part of a cultural fishery” like the one at Grassy Narrows, said Mr. Sone. “There is a responsibility for the health of First Nations. And there is the broader treaty and fiduciary responsibility for the well-being of First Nations.”

The federal government counters that the zone of contamination does not include federal lands, so its own Contaminated Site Action Plan does not apply and, it says, responsibility for addressing the contamination belongs to Ontario. It also points out that Health Canada has been monitoring the mercury levels in the people of Grassy Narrows for decades.

From 1962 to 1970, mercury from Reed Paper’s chemical plant in Dryden, Ont., upstream from Grassy Narrows, was dumped into the English-Wabigoon River system. A former worker at the paper mill has also confessed to participating in the 1972 burial of salt and liquid mercury in a pit behind the facility.

A report commissioned by the Grassy Narrows First Nation and released earlier this year says remediation of at least some parts of the river is feasible. The first step, the report says, would be to stop any further release of mercury from its source. After that, it says, there are several options for cleaning the water, the best of which would be to add low-mercury solids to the water, allowing them to settle on the bottom and dilute the mercury into the sediment.

Ontario Premier Kathleen Wynne has not acted on those recommendations, saying she is concerned that moving sediment on the bottom of the river could cause further problems.

But John Rudd, one of the world’s foremost experts on mercury remediation and the lead author of the report, says he believes the Ontario government misread what he wrote. “The top-rated options were two very benign approaches that we don’t think would cause any damage at all,” said Dr. Rudd in a telephone interview. “They also happen to be the least expensive.”

Dr. Rudd headed the first federal-provincial studies of Grassy Narrows in the 1980s and says there is much the federal government could do to assist in the river’s cleanup. “We would like to have their input,” he said, “and if their people are busy, we could do with funding, for sure.”

Japanese researchers have been studying the effects of mercury on the human population in Grassy Narrows for four decades and say symptoms of poisoning can be seen even in those who were not yet born when the plant was operational.

In 1985, the federal and provincial governments, along with Reed and Great Lakes Forest Products, which had bought the plant, agreed to pay nearly $17-million to the people of the First Nation to compensate them for their health problems. But the contamination remains.

Mercury concentrations in the walleye in Clay Lake, which is part of the Wabigoon River watershed, are still two to 10 times higher that normal, according to Dr. Rudd and his colleagues.

“Imagine a community anywhere in this country where it was reported that 90 per cent of the population had been exposed to mercury poisoning. There would be officials on the ground immediately and there would be an action plan,” said Charlie Angus, the indigenous-affairs critic for the federal New Democrats.

Instead, said Mr. Angus, “We have a Prime Minister who hasn’t even bothered to return letters to the community. The disinterest of federal officials over this catastrophe is absolutely astounding.”