Mercury is a naturally occurring element found in river bottom soil; however, when disturbed, as it often is by the construction and operation of dams, it gets converted to methylmercury. This toxic substance then bioaccumulates throughout the food web. Methylmercury is absorbed into the human body about six times more easily than inorganic mercury making this compound extremely dangerous to those that rely on these rivers for their food, water, and culture.

Amy Norman, a Labrador Land Protector fighting megadams on the Mista Shipu (Churchill/Grand) River discusses methylmercury, a potent neurotoxin that accumulates in food webs as a result of flooding caused by dams and their reservoirs. Methylmercury disproportionately impacts Indigenous communities causing severe health issues, food insecurity, and cultural genocide.

Research conducted by Harvard University on dozens of dams proposed or under construction in Canada finds that 90% of them expose people who eat foods from these rivers to unacceptable levels of methylmercury. In 2016, the Nunatisavut Government published the Lake Melville: Anativut, Kanuittailinnivut Scientific Report. The primary research objective of this study was to understand how Muskrat Falls (a Nalcor hydropower facility) would impact the Lake Melville ecosystem and Inuit who depend on it for their well-being. The findings of this study have created a robust understanding of the Lake Melville ecosystem and potential future changes created by megadams. These findings show that not only have megadams increased the methylmercury content in rivers, but they have also altered key lake and river processes which have lasting impacts on front-line communities.

Exploring the impacts of reservoirs and dams on freshwater health: Methylmercury