Great Lakes eco-region

This lake system contains the largest supply of freshwater in the world.

During the last ice age, a mile-thick ice sheet covered the area. The massive weight and movement of this glacier gouged out the earth to form the lake basins. About 20,000 years ago the climate warmed and the ice sheet retreated. Water from the melting glacier filled the basinsoffsite link and the Laurentian Great Lakes were formed. Approximately 3, 000 years ago, the Great Lakes had formed into their present shapes and sizes. Today, the Great Lakes eco-region contains a wide variety of habitats including: aquatic, forest, marsh, wetland, and dune ecosystems. Widely varying climate, soils, and topography of the region, in combination with these diverse ecosystems, support more than 3,500 species of plants and animals.

This visualization, using photo bars, shows impacts of rising lake levels at a set location.
NOAA’s Lake Level Viewer for the Great Lakes
The viewer uses high-resolution elevation data, enabling users to display and visualize water levels associated with different lake level scenarios with a high degree of accuracy.

Humans are also a part of the Great Lakes system. Commercial and sport fishing, agriculture, recreation and tourism, manufacturing, and shipping are all important to the region. These activities create jobs, and provide needed goods and services . The fishing industry extracts over 65 million pounds of fishoffsite link per year from the lakes, contributing more than one billion dollars to the region's economy. Agriculture produces corn, soybeans, hay, milk, and other food products. The area is also known for its heavy industry which produces steel, chemicals and other products that people use. A long and dangerous history of shipping on the Great Lakes played a critical role in settlement of the region and development of industry. Today more than 200 million tons of cargo pass through its water's each year.

Asian carp pose a threat to boater safety, fishing, and ecosystem health. The commercial bait trade remains a potential pathway for Asian carp and other invasive species to spread.
New molecular tool screens bait fish for invasive species risk
One potential pathway for aquatic invasive species introductions is the commercial bait trade; anglers commonly release unused bait fish back into lakes and streams.

There are a number of threats to the Great Lakes' ecosystems, including: invasive species, climate change, pollution, and habitat destruction. Climate change affects water temperatures, weather patterns and lake levels. Pollutants from residential, agricultural, and industrial areas reduce water quality. Land development decreases the amount of wildlife habitat. Fish populations have been declining in recent years as a result of these threats and increased fishing pressure.


"The Great Lakes are socially, economically, and environmentally significant to the region, the nation, and the planet." This an essential principle for Great Lakes literacy. The Great Lakes Literacy Principles and Fundamental Conceptsoffsite link provide a framework for educators teaching about the Great Lakes, helping teachers and students think, teach and learn of the Great Lakes as a system, rather than a set of unrelated parts. Thinking systemically can provide for a greater understanding and can help provide solutions to the issues threatening the region.

Adapted from: About Our Great Lakes, NOAA Great Lakes Environmental Research Laboratory

Last updated: 10/5/2015