Do hydropower projects produce mercury?
Hydropower projects do not produce mercury. Most of the mercury found in the environment comes from smelters, incinerators, and coal and oil-fired plants, although some is naturally occurring. By displacing coal and oil-fired electricity plants, hydropower can in fact contribute to the reduction of mercury emissions. The flooding of large expanses of land can contribute to increased mercury circulation and facilitate its absorption by fish. For that reason, fish found in new hydropower reservoirs can contain higher levels of mercury; however, these levels decrease after 20 to 30 years, reaching levels similar to those found in natural lakes. That mercury particles are dispersed in the atmosphere and accumulate in the environment, including water expanses, is a North American issue, which hydropower can help address.
