Big lakes (North America)

Various lakes

Four of these lakes span the border américo-canadienne ; the Lake Michigan is only located entirely on the territory of the the United States. The Big lakes are thrown in the Fleuve the St. Lawrence which delimits same the Frontière for a portion of its course.

A sixth lake, small the lake Holy-Claire, being between Lake Huron and the lake Érié, also forms part of the system but is not counted officially among the Big lakes. In fact, one can observe thousands of small lakes in this area. live in the basin of the Big lakes. Several Métropole S is located on banks of these lakes: the most populated are Chicago, Toronto and Detroit gathered in a transborder space called Main Street America. The area of the Big lakes is also an important industrial basin.

Environment, ecology

In spite of their size, the big lakes knew a increasing Pollution and locally alarming by the Heavy metals and various chemicals (starting from Toronto and Hamilton in particular). The exemption from payment of water and the low costs of energy and wood, as well as the eases of transport per water way attracted around the big lakes of the iron-foundries, the paper mills, the chemical plants, production of cars and many other manufactured goods which massively polluted the lake lasting more than one century for some, of which with metal remanent products and POPs liposoluble found in all the food chain, until at the Beluga S and Baleine S of the estuary of the St. Lawrence.

The lakes receive salts of snow clearance. They receive also more eutrophisant S of agricultural and urban origin (sewers) which they cannot degrade. To this are added serious and new ecological problems related to the increasing concentrations of product affecting the fertility or behaving like lures hormonal, or related to the introduction of invasive species (Moule streaked for example). In 1980, the international Joint Committee had identified 42 priority sites considered to be “alarming” because of the gravity of the pollution of their water. It is also necessary to fight against air pollution: the rains which wash the plumes of pollution contain mercury, pesticides, nutrients and many pollutants emitted by the factories, the vehicles and the cities: from 90 to 95% of the chemicals which contaminate the lake Supérieur would have an atmospheric origin.

Since the years 2000, a new difficulty also seems to arise with accumulation in the sediments of the St. Lawrence of toxin LT produced per number of the transgenic plants (GMO) abundantly cultivated in these areas, alerts a French ecotoxicologist, as well as the Center the St. Lawrence d' Environnement Canada and the Research institute in biotechnology of Montreal which discovered abnormal and alarming concentrations of LT accumulating in the sediments of the St. Lawrence river, with the mouth of the rivers Châteauguay, Richelieu and Yamaska.

Since the agreements signed as from 1978 between the United States and Canada, various programs of rehabilitation and follow-up are in hand to cleanse the lakes and to decontaminate the St. Lawrence river, with the governments, communities, schools and ONG, with more or less significant results according to the pollutants. The industrial acid emissions were strongly reduced, but of other pollutants continue to pose problem.

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