The Great Lakes are important because they contain 20 percent of the world's fresh water and exhibit tremendous biodiversity. They are also a vital water source and play an important role in transportation and the U.S. and Canadian economies.
The Great Lakes are a chain of five North American lakes containing the second largest accumulation of fresh water on Earth. Only the polar ice caps contain a larger percentage worldwide fresh water. This makes the Great Lakes an important freshwater ecosystem. Approximately 150 species of native fish reside in the Great Lakes, and because of this, the lakes have historically been an important part of North America's fishing industry. Unfortunately, fishing in the Great Lakes has greatly reduced as pollution and invasive species have depleted native commercial fish populations. This decrease in fish harvest is an important indicator of the overall health of the lakes themselves.
The Great Lakes watershed region supports 7 percent of the agricultural production of the United States and 25 percent of Canadian agriculture. Apart from water for agriculture, the Great Lakes supply 25 percent of Canada and 10 percent of the United States with drinking water. Over 150 tons of cargo move over the Great Lakes each year. The lakes provide for the transport of goods within North America, and through the Saint Lawrence Seaway, ships pass from the Great Lakes to the Atlantic Ocean.