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TEACH Questions & Answers

How many times do you clean the Great Lakes a year? What chemicals are used in the process?
from Charles of Post Middle School in Detroit, Michigan, Age 13

Unlike a swimming pool, the Great Lakes are not cleaned by chemicals, such as chlorine. However, the lakes do have a natural cleaning and purification process. Wetlands, which are moisture-rich land areas found around rivers, lakes, and streams, store water during times of flood. The wetlands filter sediment and other pollutants out of the water, and when the water is naturally released back into the water source, such as in a time of drought, the water is cleaner.

Humans can also clean up the lakes (although we are also the main reason for lake pollution). Dredging, which is the removal of sediment from the bottom of a waterway, is often used to rid the lake or river of contaminated sediments. Many policies and laws that are passed by state governments also help clean up the lakes, such as the Great Lakes Water Quality Agreement of 1978. And check out TEACH's Areas of Concern module to find out what the Great Lakes region is doing to clean up the most polluted areas of the Great Lakes region.

Thank you for your question!

Answered on August 1, 2000

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