Great Lakes Fact Sheet #2: Lake Profiles

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PublishedMarch 6, 2013

What makes each of the Great Lakes unique?

The Great Lakes were formed nearly 20,000 years ago, at the end of the last ice age. Glacial meltwater from the retreating continental ice sheet filled the region and carved out fresh water basins, forming the lakes. The Great Lakes are the largest freshwater system in the world and, taken together, account for about one-fifth of the world’s surface fresh water. With the exception of Lake Michigan, which lies entirely within the United States, the border between Canada and the U.S. runs through
the middle of the lakes, making Great Lakes issues a key focus of binational relations. The lakes have inspired their own wannabes over the years. In 1998, the U.S. federal government declared Lake Champlain the sixth Great Lake, but the designation was widely ridiculed because the lake is so small in comparison to the real Great Lakes.

The Great Lakes region faces a variety of challenges, and many of them are broad-reaching concerns common to all the lakes — invasive species, loss of wildlife habitat and populations, harmful pollutants and climate change. However, each lake also has its own unique ecological characteristics and, as a result, faces its own specific challenges for management and remediation.