Large-scale Hydro Power

Canada has more fresh water in its lakes and rivers than any other country in the world. Many of Canada’s largest rivers have been used to produce electricity. In fact, 61% of Canada’s electricity comes from the energy of falling water. Electricity generated this way is called hydroelectricity.

Figure 1 62% of Canada’s electricity comes from hydroelectric

Hydroelectric facilities often depend on a dam to raise the level of the water in the reservoir. Water from this reservoir is allowed to fall through huge pipes to a building that houses water-driven turbines. Pressure from the falling water spins the turbines at high speed. The turbines are connected to huge generators that make electricity as they turn. This electricity is carried to cities and towns that may be located hundreds or even thousands of kilometers away.

 

Large-scale hydro usually has a big impact on the ecology of the river upstream from the dam. When the reservoir is filled, areas of forest or farmland are covered by water. Dams block the natural migration of fish and other creatures up and down the river, and replace a flowing water ecosystem with an artificial lake. Salmon, which travel up rivers to spawn, are particularly affected by this ecosystem change. To reduce the impact of dams on salmon, some dams are equipped with “fish ladders”-narrow artificial streams up which the salmon can swim to get around the dam.

Figure 2 Fish ladders such as this can help salmon and other migratory fish swim upstream around a dam or other artificial obstructions of the stream.

There can also be environmental problems downstream from the dam. Operations of the dam and generating station often cause the water level in the river to rise and fall drastically on a daily basis. Many organisms including most fi sh are not well adapted to such frequent and severe changes in water levels. Rivers that experience these changes usually contain far fewer organisms than they would without the dam and reservoir.