Focus On Planet Earth - SOUTH AMERICA ECOSYSTEMS WATER.

SOUTH AMERICA ECOSYSTEMS WATER

Water is one of the most common concerns of Americans and Canadians. Despite an overall relative abundance, water shortages occur periodically in some localities, such as the more arid sections of the western United States, the Canadian prairie, and some of the valleys in the interior of British Columbia.

Canadians and Americans are among the world s largest per capita consumers of water (See Table 2.10.) especially where prices are relatively low. For example, Canadian households use twice as much water as European households, but they pay half as much for it. (See Table 2.11.) In 1994, Canadian households that paid volume-based water rates used 258 litres per person per day, nearly 40 per cent less than those charged a flat rate (Environment Canada, 1996d).

Eleven per cent of all surface and ground water withdrawn in Canada is used for municipal purposes. While one in four Canadians relies on ground water for domestic supply and the remainder depend on surface water, both sources are coming increasingly under threat in terms of quantity and quality (Environment Canada, 1996d). Because of increasing demand, municipal water supply is becoming one of the most critical water issues in the region (Environment Canada, 1996d; EOP, 1993). For example, in 1991, one in five Canadian municipalities reported problems with water availability (Environment Canada, 1996d). Linked to this is a growing concern for how to prevent resource depletion and reduce the environmental burden caused by the use of water for both industrial and community needs.

Compared with most other countries, Canada and the United States enjoy relatively good water quality. Nevertheless, basic delivery problems remain in some rural areas. Improper agricultural production practices have in some areas contributed significantly to impaired water quality of rivers, lakes, and estuaries (PCSD, 1996). In Canada, recent surveys suggest that 20 to 40 per cent of rural wells may be affected by faecal coliform bacteria (Government of Canada, 1996). A U.S. Department of Agriculture study in 1995 concluded that 2.4 million rural Americans, including a million without piped water, had a critical need for safe, dependable drinking water; supplies to a further 5.6 million did not meet Safe Drinking Water requirements (EPA, 1996a). The cost of meeting "highest priority" safe drinking water needs in rural America was estimated at US$3.5 billion.

One in five U.S. citizens receives water from a facility that violates a national safety standard. Surface water treatment standards were not met in 9 per cent of the systems while total coliform bacteria levels exceeded permitted levels in 8 per cent of the systems. Lead and copper treatment violations occurred in 1 per cent, as did chemical or radiological contamination violations. Through aggressive action under the Surface Water Treatment Rule by responsible authorities, the risk of human exposure to microbiological contaminants is being reduced. In 1993, 1,000 water systems serving 12 million residents were not in compliance; by 1995, the number of non-compliant systems had been reduced to 400, serving 9.9 million (EPA, 1996a). Since 1972, the United States has invested a total of US$350 billion to control water pollution (NSTC, 1996).

Most Canadians get their drinking water from municipal water supplies, which generally meet high provincial and territorial safety standards. However, a 1995 report entitled "Community Drinking Water and Sewage Treatment in First Nation Communities" indicates that in those Aboriginal communities, about 20 per cent of the water systems require action to eliminate the risk of potential health problems while 9 per cent of the sewage systems have problems that could put human health at risk (Canadian Dept. of Foreign Affairs and International Trade, 1996).

The largest system of fresh surface water on earth, containing approximately 18 per cent of the world supply, is situated on the Canada-U.S. border. The Great Lakes-Superior, Michigan, Huron, Erie, and Ontario-together with the St. Lawrence River system, are a vital part of the physical and cultural heritage of North America. Spanning more than 1,200 kilometres from east to west, these inland fresh-water seas provide water for consumption, transportation, power, and recreation. The basin ecosystem is home to more than one tenth of the population of the U.S. and one quarter of the population of Canada. Some of the world s largest concentrations of industrial capacity are located in the Great Lakes region. Nearly 25 per cent of the total Canadian agricultural production and 7 per cent of the American production are located in the basin (Environment Canada and U.S.-EPA, 1995).

Beginning in the 1950s, concerns arose about the increasing eutrophication of the lakes, loss of wetlands and other habitats, the impact of exotic species on native fish stocks and aquatic ecosystems, and environmental contamination by persistent toxic chemicals. Concerted, system-wide efforts by both governments over the intervening years have done a great deal to restore environmental quality. Nutrient stresses are no longer the widespread problem that they were in the 1970s. There has been a general decline in the concentrations of persistent organic substances in all media throughout the Great Lakes. The aquatic community in Lake Superior is in good health again.

Despite these and other improvements, the latest State of the Great Lakes report, issued by the governments of Canada and the U.S. (Environment Canada and U.S.-EPA, 1995), concludes that the health of the Great Lakes Basin ecosystem is still variable. For instance, many toxic contaminant loadings remain above acceptable levels in water, aquatic organisms, and fish-eating birds. Aquatic habitats and wetlands are considered to be in a generally poor state due to huge losses acquired over the years in both quality and quantity.The ecosystem balance and reproductive impairment of native species in Lakes Michigan, Ontario, and eastern Erie are still worrying. Joint efforts are continuing to address, in an integrated manner, the Great Lakes environment. (See Chapter 3.)

United Nations Environment Programme