The chief of Grassy Narrows First Nation says the community is still reeling after a former worker at the Dryden, Ont., paper mill revealed he was involved with dumping drums of toxic chemicals into a plastic-lined pit decades ago.

"We're very, very concerned," Chief Simon Fobister said Tuesday morning.

Grassy Narrows First Nation demands action after mercury dump site revelation1:12

Reed Paper's chemical plant in Dryden was a source of mercury contamination in the 1960s and '70s. Chemical leaching from the plant has been well documented and continues to cause public and environmental health concerns.

In a report released in May, environmental scientists determined that current mercury levels in the waters around where people in Grassy Narrows catch and eat fish suggest there is an unknown source of mercury contributing to the problem.

The Ontario Ministry of Environment and Climate Change says it's known about and monitored the dump site all along, but Fobister doesn't believe that.

"This is a new site that no one was aware of until this man admitted that there is another site that has barrels of mercury, and we don't know if those barrels of mercury are leaking into the water table and again contaminating the waterway," he said.

Mercury 'pooling around my shovel'

In an email sent in the summer of 2015 that was obtained this week by CBC News, former Reed Paper employee Kas Glowacki said feelings of guilt moved him to share what went on in 1972 when he worked as a labourer at the plant.

grassy narrows fishing sihouette

A government-funded report released this spring says there's an ongoing source of mercury poisoning the waterways near Grassy Narrows First Nation in northern Ontario. People there think a former mill worker may have provided them with answers. (CBC)

"I am writing this letter out of guilt and possibly to share some info you might not be aware of," Kas Glowacki wrote.

"I was amazed at the amount of mercury that was pooling around my shovel as I dumped it into the drums …. The drums were dropped, not placed, into the pit."

When a toxic chemical such as mercury leaks into a freshwater ecosystem, it is often absorbed by tiny aquatic invertebrates. Those little creatures are then consumed by minnows, which are devoured by larger fish that are then caught and eaten by humans.

As the mercury travels up through the food chain, mercury concentrations build up and magnify, "causing increasing levels of harm on higher order species such as predatory fish" and ultimately humans, Environment and Climate Change Canada says.

Biomagnification in the food chain

When mercury gets into the a water table, it's eventually absorbed by tiny primary consumers like zooplankton, which are then swallowed up by tiny minnows. The minnows are consumed by larger fish, "causing increasing levels of harm on higher order species such as predatory fish," birds and ultimately humans, Environment and Climate Change Canada says. (CBC News Graphics)

Fobister said to his knowledge, the site still hasn't been located, and he wants the Ontario government to step in and investigate.

He wrote to Ontario Environment Minister Glen Murray to explain how disconcerting Glowacki's letter has been to the community, where residents continue to suffer from mercury poisoning.

'No more fancy talk'

"No more fancy talk. No more studies. We just want it cleaned up," Fobister said. 

Judy Da Silva from Grassy Narrows, who suffered from mercury poisoning at one time, said the letter points to a second dump site away "far from the place that the minister of environment said."

Chief Simon Fobister , 'No more fancy talk. No more studies. We just want it cleaned up.'2:39

"All these years, we lived with this mercury poisoning, and we're always being minimized, always being told natural sedimentation will bury the mercury," Da Silva, who is also the environmental health co-ordinator at Grassy Narrows, said Tuesday.

"For us, for me, as a mother and grandmother, I feel it's a betrayal to my people, the Anishinabek, that this was not brought forward."

Ontario Premier Kathleen Wynne weighed in Monday, saying she is dispatching two government ministers and scientists to get to the bottom of the latest developments at Grassy Narrows.

"There's engagement right now to try to discern what this alleged source is," Wynne said. "I don't have all that information. I want to get to the bottom of it."

Fobister has asked for access to the mill site in hopes of tracking down the alleged dump site.

Mercury doesn't discriminate

Da Silva added that while Grassy Narrows and the surrounding area have been the hardest hit by toxic dumping from the old paper mill, if a second site exists and isn't uncovered, it could have far-reaching affects for other communities further downstream.

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'It's a war zone. I can't say enough how we need that river to be cleaned up,' Judy DaSilva, the environmental health co-ordinator at Grassy Narrows First Nation, said at the end of May. 'Our relatives are dying.'

"Mercury doesn't stop in Grassy Narrows, it doesn't stop at Indigenous populations," Da Silva said.

"The mercury is not a racist mercury. It goes to other communities, and we're not the only ones in danger of this. Canadian society needs to really look at that and help us get the river cleaned up."

Grassy Narrows is about 55 kilometres northeast of Kenora, Ont., and about 225 km east of Winnipeg. It is also known as Asubpeeschoseewagong First Nation.

With files from Jody Porter and CBC Thunder Bay