In 2011, Ontario emitted 170.6 megatonnes of greenhouse gases (GHGs), second in Canada only to Alberta. Greenhouse gases are any gases that contribute to the greenhouse effect and deteriorate the earth’s atmosphere. The great thing about hydroelectric power is that no fuel is being burnt and so it does not contribute to Ontario’s greenhouse gas output. The only pollution from hydropower comes from the construction of the power plants, as well as methane being released when vegetation and trees are removed to create reservoirs and redirect rivers towards generating stations. An environmental benefit of hydropower is there are no waste disposal issues like there are in plants run by nuclear or fossil fuels.
There are however, environmental consequences that come from using hydropower as well. Fish habitats can be altered not only from rivers being dammed for hydro plants, but also from the change in river patterns caused by having the dam there, and the mass amounts of water can trigger geological events such as earthquakes. People are sometimes forced to relocate and leave their houses and business due to flooding of dams as well.