The Great Lakes hold more than 20% of the world's surface fresh water
It takes some audacity to be named the Great Lakes. After all, there are millions of lakes on planet Earth. But when it comes to North America's fascinating freshwater system, the adjective “great” is well earned. Consisting of five lakes — Huron, Erie, Superior, Ontario, and Michigan — the Great Lakes stretch some 94,600 square miles, making them one of the largest surface freshwater systems in the world. In fact, these lakes are so big that they include more than 20% of the world’s surface fresh water, or 6 quadrillion gallons of it. That’s so much water that if you spilled the entire contents of the Great Lakes throughout the Lower 48, the entire contiguous U.S. would be submerged in nearly 10 feet of water.
With such an abundance of fresh water and natural resources, the Great Lakes have been a hotbed for human habitation. But over the years, increasing activity around the lakes has led to an onslaught of industrial, urban, and other pollutants, as well as more than 100 non-native and invasive species that have damaged their ecosystems. Because less than 1% of the water in the Great Lakes leaves the system each year, pollution can linger for a very long time. Today, environmental organizations and government agencies in both the U.S. and Canada are working together to make sure the Great Lakes stay “great.”