The Great Lakes

Dr. Pence's Comments on Water Supply Issues Page
The Great Lakes are some of the most researched lakes in the world at the moment. This is most likely due to what happened with the Aral Sea. Over a short period of time the Aral Sea began receding and now it is nothing near what it used to be. Another example of this (which this? Do you mean it is receding or that there is a problem with pollution?) is the Dead Sea.

The Great Lakes basin, which consist of Lakes Superior, Michigan, Huron, Erie, and Ontario, and the
For more general facts about the great lakes check out the EPA's website.
areas that drain into the lakes. This area contains 18% of the world's fresh surface water. In addition to being a major drinking water contributor the Great lakes are also a source of hydroelectricity and they are also the sites of many industrial, commercial, agricultural, and urban developments. 1

One of the main man-made causes for the dropping water level comes from the dredging of St. Clair River. By deepening the river more water is drained into Lake Ontario, which will then drain out into the Atlantic Ocean. Natural causes include drought and evaporation. As global temperatures increase more and more water evaporates without equivalent rainfall to bring the levels back up.2

The Great Lakes get their water from inflows from the upper lakes in the chain and from precipitation. The precipitation not only fall on the lakes but also on their drainage basins which eventually flow into the lakes. They lose water through evaporation, outflows, and consumptive uses. If the difference between the amount of water coming into the lakes and the amount going out are about the same the water levels will remain steady, however if there is too great a difference then the water levels will drain drastically or be much above normal. 1

Living near the Great Lakes has its perks and risks. Higher water levels can increase the risks of shoreline flooding, erosion, and damage caused by waves during storms, which is problematic to residents, industries and commercial operations along the lake shores. When there are high water levels ships are allowed to carry heavier loads, But extremely high levels flowing through the connecting channels can cause navigation problems. On top of shipping advantages high levels can also be beneficial for hydroelectric plants. The more water the more electricity. During extremely high water levels, however, the amount of water available to these plants can exceed their capacity and be spilled onto nearby shores.1
Map of the Great Lakes Water Basin

On the contrary if water levels ever become too low the cargo ships that sail across must lighten their loads or the risk of running aground will be too high. On top of that if they are no longer carrying full loads, they'll need more trips, thus costing more money (andd energy?). Low water levels may also increase the size of lake shore beaches, but when levels get extremely low it can expose unsightly and, sometimes, hazardous rocks, mudflats, and other potential problems for swimmers and boaters.

The Great Lakes also play a major role in the region's weather, this is called the "lake effect." In the summer the lakes can moderately cool temperatures in the surrounding areas by absorbing heat, and in the autumn it releases the heat to warm the region. Due to this "lake effect" fruits that normally grow further south are capable of being grown in this region.4

Currently in the great lakes there are over 360 chemical compounds that have been identified, among them are: alkylated lead, benzo(a)pyrene, DDT, mercury and mirex. These few are all potentially dangerous to humans and are destructive to the aquatic ecosystems which inhabit there. There are species of fish which have almost completely gone extinct.

The problems faced by the Great Lakes are being dealt with in various ways and policies.

1. "Freshwater Website: Lakes (The Great Lakes)" Environment Canada (July 25, 2008)
2. "The Great Lakes," Great Lakes Information Network (September 17, 2008)
3. "Great Lakes." Environmental Protection Agency (January 27, 2009)
4. "The Great Lakes"
Wikipedia (February 14, 2009)
5. Flesher, J, "Study: Erosion Causing Great Lakes' Water Loss"
redOrbit// (August 15, 2007)