According to the definition provided by the International Commission on Large Dams (ICOLD), the term “large dam” refers to

• any dam over 15 metres in height from the lowest point of the foundation to the crest, or
• any dam between 5 and 15 metres in height with a reservoir volume of more than 3 million cubic metres.

There are about 45,000 large dams in the world. Over half are used exclusively for irrigating agricultural land. About one out of four generate electric power. Of Canada’s 793 large dams, 226, or just over one quarter, are located in Québec.

Hydro-Québec operates over 550 dikes and dams.