Scientists back Inuit in efforts to limit mercury poisoning risk from Muskrat Falls hydro project

An almost two-week occupation at the site of a multibillon-dollar hydroelectric project in Labrador is winding down after Newfoundland and Labrador Premier Dwight Ball vowed to make all future decisions "using science-based research."  

That marks a significant victory for the Inuit, whose protests and hunger strikes were based on studies out of Harvard University that warned the Muskrat Falls project would poison their food sources if the government didn't take steps to prevent methylmercury from being released into their waterways.

"The decisions that will be made, going forward, will not be at the whim of government," Todd Russell, the president of the NunatuKavut Community Council, said on Wednesday. "They will be made by science and it will incorporate the traditional knowledge of our people. This is a huge step forward."

• A look back at methylmercury concerns in Labrador
• Labrador leaders make 'significant' Muskrat Falls progress
• Muskrat Falls protesters 'fighting for land and food'

So how does a project aimed at providing a greener source of energy jeopardize Labrador's fish, wildlife and people? Here's a breakdown of the science behind the methylmercury risk linked to the Muskrat Falls project.

What is methylmercury?

Methylmercury forms in nature when bacteria reacts with mercury in water, soil or plants, in a process called methylation.

Its levels increase as it moves up the food chain — for example, from algae to plankton to fish to people. Eating food from water with even low levels of methylmercury can be dangerous. 

"You could drink a swimming pool of this water every day and it would not affect your health," Trevor Bell, a Memorial University of Newfoundland geographer and project leader on a study of methylmercury risks with the Muskrat Falls project. 

"When you get to the top of [the food chain], the fish and the seals, that's 10 million times the concentration as in the water."

Why is it dangerous?

According to the U.S. National Library of Medicine, methylmercury poisoning can cause serious brain and spinal cord damage, resulting in blindness, growth problems, impaired mental functioning, birth defects and potentially cerebral palsy.

The worst example of its effects are in Japan's Minamata Bay, where more than 1,000 people died and thousands more were were sickened by seafood from waters polluted by mercury from the Chisso Corporation's chemical factory in the 1950s.

In Canada, First Nations people in Grassy Narrows, Ont., continue to suffer the effects of mercury poisoning from Reed Paper's chemical plant in the '60s and '70s.

How can a dam poison the water?

Muskrat Falls is not a chemical plant, and it won't be dumping mercury into Labrador's ecosystem.

It doesn't have to, because the mercury is already there. Some of it occurs naturally in soil, and some is deposited by precipitation from industrial emissions worldwide.

Nalcor, the provincial energy company behind the Churchill River hydroelectric project, wants to flood the Muskrat Falls reservoir to construct its dam.

That could create the conditions for mercury to turn into methylmercury, because it would unleash carbon from the soil and plant life, fuelling methylation.

That reservoir is just upstream from the Lake Melville marine estuary —  the Inuit's primary source of fishing and hunting.

Studies led by Bell and conducted in conjunction with the University Manitoba and scientists from Harvard University found the flooding could elevate methylmercury in Lake Melville far beyond what naturally occurs. 

Nalcor's environmental assessment presumed the methylmercury would be diluted in the estuary, but the Harvard researchers found the mix of fresh and salt water would prevent that from happening, and would even accelerate the biomagnification process. 

"When fresh and salt water meet … salinity increases as water deepens. This stratification allows fluffy organic matter that typically sinks to the bottom to reach a neutral buoyancy — meaning it can't float up or down in the water column," explains a Harvard Gazette article summarizing the research.

"This layer, called marine snow, collects other small settling debris and concentrates it into a feeding zone for marine plankton."

What can be done?

In 2011, a joint review panel recommended the best way to deal with the effects would be full vegetation clearing. It also recommended Nalcor and the federal government launch a study to determine the feasibility of clearing reservoirs in general of both vegetation and topsoil.

"If you remove that fuel, then you very much slow or eliminate the conversion to methylmercury," Bell said. 

No study was ever launched and Nalcor later agreed to partially clear the vegetation.

In April 2016, the Harvard team released more research, suggesting methylmercury levels could rise as much as 380 per cent if only partial clearing takes place in the reservoir.

"The bottom line is hundreds of Inuit individuals will be affected by this development," researcher Elsie Sunderland said at the time. "To the point that they exceed regulatory thresholds for exposure."

​A win for science

Armed with this knowledge, protesters began occupying the reservoir last week to block the flooding.

"We're fighting for our land and our food," protester Pauline Williams told CBC News.

On Wednesday, the province and Indigenous leaders reached an agreement that will create a special committee of scientists to explore ways to reduce methylmercury contamination, and open the door to possibly clearing the reservoir.

Bell said it's a win for grassroots democracy and science-based policy. 

"The agreement is important for Labradorians and for Muskrat Falls, but has an impact beyond Labrador and nationwide on hydroelectric developments and evidence-base decision-making," Bell said.