Influence of man

The map shows dam sites and reservoir capacity in 1969, the water diversions in 1975, the steam-electric generating station greater than 20 megawatts operating in 1974, the industrial waste disposal well sites in 1970, the irrigated areas in 1970 and the drained and protected areas in 1970. There are many areas where man can have a profound influence on natural water systems. Although they cannot be illustrated in map form, particularly on the scale of this map, the following can be considered as areas where man can have deleterious effects on the water environment. Although 90 per cent of Canada's population is concentrated within 150 miles of the international border, approximately 60 per cent of the nation's total runoff is carried by rivers which flow away from densely populated southern areas. Many schemes have been proposed for diverting water from these rivers to increase the water supply in the southern parts of the country. The few diversions constructed to date have been relatively small and local in scale, and designed primarily for power. Reservoirs may be designed for the purpose of influencing streamflow through their available storage capacity. The storage, by moderating peak flows, provides a measure of flood protection, affects recreational potential, changes the movement of sediment, influences the temperature regime, and alters the groundwater regime in the area surrounding the reservoirs. Dams may help or hinder transportation, the movement of fish, and the river's ability to purify itself. At year-end of 1974, there were over 19 000 megawatts of steam-electric generating capacity installed in Canada. This is expected to grow to about 50 000 megawatts by 1985 and perhaps as high as 250 000 megawatts by year 2000. The locations of the 58 stations with more than 20 megawatts capacity at the end of 1974 are shown on the map. For the past 20 years various wastes that are difficult or dangerous to dispose of on the surface have been injected into deep wells. Since all groundwater is moving, though very slowly, great care is required to ensure that migration of such wastes does not lead to pollution of usable groundwater or other subsurface resources or to their reappearance at the surface. The map depicts 31 registered disposal wells in Canada as of 1970.