Aquatic and terrestrial ecosystems are permanently altered and/or destroyed by large hydro development. Over the last 70 years, the Canadian hydropower industry has inundated hundreds of thousands of square miles of boreal forests, peatlands, wetlands, and other habitats with flooding. 

According to the Food and Agriculture Organization of the United Nations, biodiversity in freshwater ecosystems is being lost more quickly than in any other ecosystem with an 88% decline in freshwater megafauna between 1970 and 2012.

•Recent research proves that hydro dams are a major driving force behind mass extinctions. “We know flooding reservoirs causes immediate loss of habitat and species, but we now find there is also a significant future biological cost as the ‘extinction debt’ is paid.”

•The damming of rivers and altering of their flows have dire effects on the organisms dependent on these ecosystems by blocking nutrients, destroying critical habitat, disrupting the food chain and causing higher amounts of stress in plants and animals, which can lead to illness, genetic mutation and/or death.

•Reservoirs cultivate excess weeds and algae, robbing oxygen from ecosystems and leading to unlivable conditions. 

•Dams and reservoirs built along rivers interrupt the flow of sediments, preventing the flow of these materials downstream and leading to massive amounts of erosion. 

•Traditional hunting and fishing grounds and ancestral lands have been flooded and destroyed by hydropower development, leading to cultural genocide. Erosion from river-flow manipulation has led to the destruction of sacred burial sites.