The Environmental Trade-offs of Dams and Hydropower
By Sophie Skaperdas
Contributor
When it comes to energy production, dams are a much cleaner alternative to fossil fuels because hydropower is a renewable source. They have many other perks, such as easily accessed water supplies and agricultural irrigation. Some can prevent flooding by adjusting flow and providing a stable navigation system. Quebec is one of the world’s biggest hydroelectricity producers; it holds 681 dams and 28 large reservoirs, as well as 61 hydroelectric stations and 24 thermal plants.
However, keeping these assets in mind, it is important to know dams and reservoirs have significant ecological impacts: The local ecosystems are disrupted by the reservoirs created upstream of the dams, flooding habitats on land and disturbing both the fauna and people from these areas. Entire trees are submerged along with the countless animal populations that inhabit them. This makes for striking scenery; treetops peeking from the surface of a wide lake, almost completely submerged.
Reservoirs collect sediment which make poor soils for plant roots. When forests are submerged, most plants quickly die, releasing methane, one of the most detrimental greenhouse gases. Some argue that massive reservoirs are useful to collect water. However, their vast surface area increases the rate at which water evaporates, which means a greater amount of water is lost overall due to the dam.
The change in water flow affects marine ecosystems as well. It is particularly devastating to fish that migrate, like salmon, steelhead, and eels. These fish have different spawning and rearing areas. When these regions are blocked apart by the construction of a dam, the populations cannot survive. The dams change the chemicals and temperature of the water as well, even rising to temperatures lethal to these species.
