Without water, life would not exist. Even though more than 70% of Earth’s surface is water, most of this is salt water, and there is only a limited amount of clean, fresh water on Earth. Both population growth and global climate change are currently affecting the water supply. As the use and demand for water continues to increase, learning how to conserve and recycle water is becoming more and more important.
The Great Lakes, which include Superior, Michigan, Huron, Erie and Ontario, are the largest group of freshwater lakes in the world, covering an area of more than 90 thousand square miles. Rainwater and groundwater from the surrounding area, called the Great Lakes watershed, drain into the Great Lakes to replenish the water supply. The watershed includes all or part of the states of Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania and New York, as well as part of the Canadian province of Ontario. About 37 million residents who live in this area rely on the Great Lakes for their drinking water. Many animals and plants that make the watershed home also rely on the water.
Many towns outside of the Great Lakeswatershed, such as Waukesha, WI, get their water from an aquifer. An aquifer is an underground layer of rock, which contains water in its open spaces. Wells are drilled into the aquifer in order to draw up the water. However, rainwater recharge of underground aquifers can take place very slowly. For instance, the water in the Ogallala aquifer, which supplies water to eight states in the Midwest, accumulated over tens of thousands of years. Today, water is being extracted from the aquifer at a rate which is over one hundred times the replacement rate.
The issue of selling or diverting water from the Great Lakes has been discussed in political arenas for years. But in the coming years, some people think that the need to transport water from the Great Lakes to other areas by tankers or pipelines will become a more pressing issue. Some politicians are looking for a national water policy to aid areas lacking the necessary water supply, but Great Lakes leaders are not so quick to support the idea. They recognize that poor urban planning and speedy over-development in some cities may have contributed to the lack of necessary water resources. They feel that it is not fair to put the Great Lakes' ecosystem at risk in order to make up for this lack of foresight by developers. As a result, the Great Lakes Compact, an agreement among eight states and two Canadian provinces to prevent water diversion from the Great Lakes, has been drafted to provide legal protection for the water supply. As of September 2008, the Great Lakes Compact was not yet in effect, as it still awaited approval in multiple states.
In an effort to avoid having to take water from distant sources, some cities are looking for sensible and efficient ways to protect their water supply through better water management techniques and conservation. For example, Las Vegas now recycles all of its waste water. In addition, there are over 13,000 desalination plants worldwide that provide drinking water from the ocean's saltwater.
Pause the video a few seconds in, when it zooms in on the map of the Great Lakes. Use the map to review the names of Great Lakes. (They are not labeled, so it will check the class's prior knowledge.) The image is also good to review which states border which lakes.
Assign directly to your students using the code or link above, without having them log in. Simply tell your students to go to
www.pbsstudents.org and enter the Assignment Code, or click on the Assignment URL to share the assignment as a link.