John Rudd is a research scientist who examined the mercury pollution in the English - Wabigoon river system 30 years ago. He's back looking at the river again. 7:51 It is feasible to clean up some of the decades-old mercury contamination in Ontario's English-Wabigoon River system near Grassy Narrows First Nation, according to new research by three experts in the field.

Reed Paper in Dryden, Ont., dumped chemicals in the river in the 1960s and early 1970s, resulting in mercury poisoning among First Nations people who ate fish caught in the area.

The possibility of remediation was first studied in the 1980s by a government research team that included John Rudd. He's the lead author of the new research commissioned by Grassy Narrows First Nation and released on Monday.

"It has been frustrating," Rudd said. "We made these recommendations in the 1980s and our report was put on the shelf."

The cleanup could cost "several tens of millions of dollars," Rudd said.

It could also save lives.

'Terminally ill'

The contamination closed the commercial fishery that was the foundation of the economy at Grassy Narrows First Nation. With little money and no local grocery store, residents have continued to eat the fish throughout the years.

Calvin Kokopenace, 17, died in 2014.

"He was terminally ill with the mercury poisoning that was dumped in our waters," his aunt Lorenda Kokopenace said. "It was deteriorating his muscles in his body and pretty soon he was in bed again and we had to take care of him like he was a little child."

The provincial government has reviewed Rudd's new report but disagrees with it, according to a spokesperson for Ontario's Ministry of Environment and Climate Change.

"Currently there is no evidence to suggest that mercury levels in the river system are such that any remediation, beyond continuing natural recovery is warranted or advisable," Gary Wheeler said in an email to CBC News.

Natural recovery stalled 30 years ago, Rudd said, noting that levels of mercury in some waterways in the area are five to 10 times "what they should be."

Ongoing contamination

That points to an ongoing source of contamination, possibly leaching from the old chemical plant, Rudd said.

"The problem is being perpetuated," he said. "If we don't do something to stop the source...the problem will continue for many, many more decades."

The province says its ongoing monitoring of the facility shows no evidence of leaching.

Rudd said the source of the ongoing contamination needs further study, but the feasibility of remediation does not.

Mercury cleanup methods recommended for the English-Wabigoon, and rejected by the government in the 1980s, have since been seen to work, successfully, at an estuary in Maine, Rudd said.

New technology has made remediation even more viable, he said.

To date, 1,064 people from Grassy Narrows and nearby Wabaseemoong (formerly Whitedog) First Nations have applied for compensation for the health impacts of mercury poisoning, according to the Mercury Disability Board.

The board was established in 1985 as part of an out-of-court settlement with the federal government, Ontario and the two paper companies involved in the contamination — Reed Incorporated and Great Lakes Forest Products Limited.

Japanese experts in mercury poisoning have expressed concerns that the board's criteria for compensation are overly restrictive.