Provincially-owned Nalcor Energy’s troubled 824-megawatt Muskrat Falls hydro generation project has hit another snag. Already over budget, behind schedule, and beset by political critics and falling enthusiasm among Newfoundland and Labrador taxpayers, the project now stands accused of threatening downstream Indigenous communities with mercury poisoning.

Preparation began on October 1 for the initial flooding of 41 square kilometres behind the dam. However, researchers based at Harvard University claim vegetation left standing within the flood zone will release methylmercury once it begins to decay in the reservoir’s water. That toxic compound already occurs at elevated levels in the area, and it will transfer into water flowing through the dam and downstream.  

This, Vice reports, “will increase methylmercury levels downstream by 14 times within 120 hours, putting the local Inuit at risk of poisoning from the neurotoxin.” The compound “is more dangerous than inorganic mercury,” the news outlet explains, “because it is absorbed into the body six times more easily. Mercury poisoning can affect fetal growth, leading to poor brain development and impaired learning.”

First Nations in northern Ontario are still coping with the effects of mercury poisoning on the English-Wabigoon river system, nearly a half-century after it was first reported.

The Harvard researchers say the threat can be minimized by completely clearing the land before it is flooded, but Nalcor concedes that less that 75% of the vegetation in the reservoir footprint has been removed “because it’s impossible to remove trees on steep slopes and near water,” Vice notes.

The Harvard team identified Rigolet, an Indigenous hamlet of 300 downstream from the reservoir, as most in danger. There, everyone fishes and hunts for food, Rigolet resident Charlie Flowers told Vice. If methylmercury bioaccumulates in such “country food” after Nalcor floods the area, he said, “that’s it for us.”

Provincial Environment Minister Perry Trimper, an environmental scientist who lives in the area, told Vice he’s open to removing more vegetation, but only “in the coming years, not before initial flooding begins.”

The Muskrat Falls project’s price has ballooned from initial estimates of $6.9 billion to $11.4 billion, prompting federal Green Party leader Elizabeth May to call on the Liberal government to rescind loan guarantees its Conservative predecessor issued for Nalcor project debt.