This water use is the principal source of electricity in Canada today. Billions of dollars have been invested in its development. With large undeveloped hydroelectric sites still available in Quebec, Newfoundland, Manitoba, British Columbia, and the territories, this form of energy development will most likely retain its prominent position for years to come. However, the environmental and human effects to be avoided or mitigated in such large projects make them increasingly difficult and costly to plan and build.

Water: A powerful source of energy

Hydroelectric Power. Wikimedia Commons (Public Domain)Hydroelectric energy is produced by the force of falling water. The capacity to produce this energy is dependent on both the available flow and the height from which it falls. Building up behind a high dam, water accumulates potential energy. This is transformed into mechanical energy when the water rushes down the sluice and strikes the rotary blades of turbine. The turbine's rotation spins electromagnets which generate current in stationary coils of wire. Finally, the current is put through a transformer where the voltage is increased for long distance transmission over power lines. In Canada, hydroelectric plants satisfy 62% of electricity demands.

The Downside to Dams

While dams have been integral to energy production and industrial development, they are also structures that significantly transform river ecosystems. As dams restrict the natural flow of water, they alter water temperatures and chemistry, which in turn influences rates of biological and chemical processes. Dams create barriers to the upstream-downstream movement of nutrients and organisms, thereby affecting physical and biological exchange processes. They also change the natural timing and amount of downstream flow of water, sediment, and ice, which modify natural cycles and therefore the structure and function of aquatic and river habitat. As dams occasionally collapse, they also present a risk to the built environment and downstream ecology. 

Adapted from Environment Canada's Freshwater Website and National Water Research Institute's Threats to Water Availability in Canada