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The Center for Great Lakes Literacy (CGLL) is a collaborative effort led by Sea Grant educators throughout the Great Lakes watershed. CGLL fosters informed and responsible decisions that advance basin-wide stewardship by providing hands-on experiences, educational resources, and networking opportunities promoting Great Lakes literacy among an engaged community of educators, scientists, and youth.


Growing a community of Great Lakes literate individuals able to steward the Great Lakes and connected freshwater resources.


The Center for Great Lakes Literacy (CGLL) engages and inspires teachers, scientists and students to develop a Great Lakes-literate public capable of effectively contributing to the sustainable use of the Great Lakes and connected freshwater resources.

Why do watersheds matter?

Understanding and protecting watersheds is important because actions upstream have consequences downstream. Water is only as clean as the land it flows over; a river or lake is only as healthy as the water draining into it. Healthy watersheds reduce flood risk, support crops, filter pollutants, mitigate effects of climate change, provide habitat for plants and animals that are part of the ecosystem, and boost human wellbeing.

What is so cool about the Great Lakes?

The Great Lakes contain about 20% of the world’s fresh surface water with about 6 quadrillion gallons (22.7 quadrillion liters) of freshwater – enough to submerge the entire continental United States in nearly 10 feet of water! The Great Lakes system includes five Great Lakes – Superior, Huron, Michigan, Erie and Ontario – and also Lake St. Clair, Lake Champlain, the St. Lawrence River, connecting channels, along with many harbors and bays. Another way to remember the names of the five Great Lakes is the acronym HOMES – which stands for Huron, Ontario, Michigan, Erie, and Superior.

A map that depicts the Great Lakes Basin with each lake watershed being called out.

Each lake has distinctive basin features, circulation and ecology. Most of North America’s surface water – nearly 95% – is found in the Great Lakes. They are shared between the United States, Canada, and many Tribal Nations. The Great Lakes coastline, measuring over 10,000 miles of shoreline, is longer than the East coast of the United States’ coastline. Approximately 34 million people in the United States and Canada live in the Great Lakes basin and depend on its freshwater. This estimate equates to about 8 percent of the U.S. population and about 32 percent of Canada’s population. More than 3,500 species of plants and animals also live in the Great Lakes basin, including 170+ species of fish.

The Great Lakes were formed more than 10,000 years ago by mile-thick glaciers. Over thousands of years, the glaciers froze, melted, refroze, and eventually completely melted. This process eroded the ground and created the Great Lakes basin, and as the glaciers melted, the lakes filled in with water. The changes in elevation – or stair-step arrangement of basins – is relatively new and the result of land rebounding from the glacier’s weight. To this day, the land surrounding the Great Lakes continues to rebound from the weight of glaciers.

A schematic that shows each of the Great Lakes depths.

Across our Blue Planet, most of the water – more than 97% – is saltwater. Protecting freshwater is important as we face global challenges like climate change.

Learn more about the Great Lakes and how they were made

Do you live in the Great Lakes region?

Is your home in the following states – Indiana, Illinois, Michigan, Minnesota, New York, Ohio, Pennsylvania, Wisconsin – or the province of Ontario? If yes, then your state or province touches at least one of the Great Lakes. If you live outside the Great Lakes basin, you are always welcome to visit this national and global freshwater treasure. In every state connected to the Great Lakes, Sea Grant educators work to help people understand how important the Great Lakes are and how taking care of them benefits everyone.

Learn more about Sea Grant

How to be Great Lakes literate?

  • Do you understand why the Great Lakes are important? (For example: they provide us with drinking water)
  • Do you make decisions that help protect the Great Lakes? (For example: Don’t litter.)
  • Can you tell others about the Great Lakes and encourage them to help protect this freshwater treasure? (For example: share with your family and friends)
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