The Great Lakes

An unmistakable geographic feature from land and air, the Great Lakes comprise the largest chain of lakes in the world. They contain more than 20% of the earth’s surface freshwater and 95% of the surface freshwater in the United States. The enormity of the Great Lakes warrants their description as ‘inland seas.’ Altogether, the lakes hold six quadrillion gallons of freshwater, a volume that could submerge the continental United States to a depth of 9.5 feet. The lakes encompass a surface area of 94,000 square miles and include 30,000 islands and 10,000 miles of shoreline. The U.S. portion of Great Lakes shoreline alone stretches the full length of the Eastern Seaboard and beyond, prompting references to the ‘Third Coast.’

A Diversity of Habitats

Spanning more than 295,000 square miles, the basin includes an immense network of streams, lakes, inland wetlands, coastal marshes, and forests. These habitats support more than 3,500 species of plants and animals, including more than 200 globally rare species and 46 species found nowhere else in the world. The Great Lakes basin provides the diverse habitats needed by more than 180 fish species to complete their life cycles. A critical stopover region for more than 350 migratory bird species, the basin provides resources to sustain hundreds of millions of birds along their migratory routes each year. In addition to supporting fish and wildlife populations, the diverse habitats of the basin provide numerous critical ecological services, including water filtration and storage, flood control, nutrient cycling, and carbon storage.

An Economic Powerhouse

With its rich tradition of agricultural production, commercial and sport fishing, industrial manufacturing, and tourism and recreation, the Great Lakes’ economic activity surpasses that of most developed nations. The lakes and their waterways transport bulk cargo from the basin to the markets of the world; since 1959, more than 2 billion metric tons of iron, coal, steel, oil, grains and other products have been shipped over the lakes. One-third of the land in the basin is used for agriculture, which is an area larger than each of the Great Lakes states except Minnesota. Tourists spend hundreds of millions of dollars each year in the basin with more than 60 million people annually visiting the many parks that dot the lakes’ shores. Additionally, the Great Lakes support a world-class fishery, which is valued at more than $7 billion annually.


Despite their importance, the Great Lakes and the broader basin have been significantly degraded by human activity over the past two centuries. Habitat loss and fragmentation, invasive species, and biological and chemical pollutants present substantial environmental challenges that impair water quality, threaten wildlife populations, and jeopardize the health and economic vitality of the region. Efforts to reduce toxic pollution and restore habitat have expanded dramatically over the last thirty years, yet a legacy of contaminated sediments, degraded water quality, and habitat loss and fragmentation continues to negatively impact the lakes and the basin as a whole. Restoration efforts have accelerated recently, thanks to an infusion of funding and the strong leadership demonstrated by the Great Lakes community. Working in coordination with a broad set of partners committed to Great Lakes restoration, Sustain Our Great Lakes is addressing many of the challenges facing the basin.


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