Hydroelectricity and the environment

Introduction

According to surveys by the United Nations and other organizations, Canadians enjoy one of the highest standards of living on the planet. Our comfortable lifestyle has been achieved despite harsh winters and vast distances between population centres. Much of our nation’s success depends on reliable, convenient and affordable supplies of energy, including hydroelectricity.

In our offices, farms and industries, electricity sustains our work on computers, telephones and machinery. At home, it powers our appliances, heating and entertainment equipment. Electricity provides many benefits, but its generation and transportation also have impacts on the environment and human health.

From water to kilowatts

Hydropower begins with the energy source —water. Generation plants harness the power of flowing water to drive turbines that produce electricity. The transmission system then moves electric power in bulk from the plants to distribution systems. Large transformers step up the voltage to carry electricity more efficiently over long distances. As the electricity nears its destination, voltages are reduced or “stepped down” at substations. Finally distribution systems move electricity to where consumers need it — in homes, industries and on farms.

Hydro power facilities provide many benefits: an abundant and affordable supply of electricity (making up about 60 per cent of Canada’s total generation capacity), low greenhouse gas emissions (and no other air pollutants), and the capacity to store water for many uses such as irrigation, recreation, energy use and water supply for our homes and industries.

But like the extraction of all natural resources, using water to generate electricity affects the environment, wildlife and people.

When large dams are built, forests and wildlife habitats are flooded and lost, and heavy metals such as mercury may be released into the water. Hydro stations and dams also change water flow in rivers and streams, resulting in potential negative impacts on fish and aquatic habitat and communities who use the waterways.

Because most of Canada’s hydroelectricity comes from large-scale projects, this section focuses on the environmental impacts of large reservoir-based hydro systems. Where possible, information is also provided on small hydro operations.