The Great Lakes [North America]
The Great Lakes. (Click to enlarge)
The five Great Lakes (Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario) make up 95% of the fresh surface water in the United States and 20% of the world. The About 38 million people live in the Great Lakes basin. In the 1960s, cultural eutrophication was identified as a critical problem for the lakes. This was caused by bacterial and toxic industrial contamination, land runoff, and acid deposition. Because water leaves the Great Lakes (via the St. Lawrence River) at a very small pace, pollutants are not washed away. This led to large fish kills and serious eutrophication by the 1960s, especially in the shallow, highly-populated Lake Erie basin.
In 1972, Canada and the United States began a $20 billion program to improve the environmental conditions. This was done through: upgrading sewage treatment plants and the technology used, improving industrial waste treatment, and banning harmful household products. Progress has been made with: fewer phosphates, bacteria, toxic chemicals, and algae blooms as well as more dissolved oxygen levels, fish, and swimmable beaches. The U.S. also passed a 1991 law requiring better cleanup of the lakes, although funding may hamper the effectiveness of this law.
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Despite these efforts, pollutions problems still plague the Great Lakes basin. These include: few clean shorelines (for swimming or drinking water), increase in nonpoint runoff from urban sprawl, 43 toxic hot spots, acid deposition, and build-up of toxic chemicals in animal populations, making many fish inedible. Suggested solutions are to ban: the use of chlorine as a bleach in the pulp and paper industry, new incinerators, and discharge of 70 toxic chemicals. The Great Lakes provides signs of hope with ongoing improvements, but efforts must be continued in order for a safe environment to be achieved for humans and other organisms alike.
Freshwater Ecosystesms (lakes), EutrophicationRelated Links
