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Features of the Laurentian Great Lakes
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Great Lakes of North America ~ NASA
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Freshwater is a fundamental resource for all life. As a consequence of ever accelerating rates of
global change, the availability of water that is both fresh and pure is one of the major issues
facing the world today. Despite living on an aquatic planet, only one-third of one percent (1/300th)
of the water on the earth is available freshwater. Industry, agriculture, commerce and people
themselves depend heavily upon these lakes. These are inland seas, not mere lakes.
- The Laurentian Great Lakes alone contain one-fifth of the world's supply of surface freshwater
- the greatest single freshwater resource on earth - 6 quadrillion gallons of water - enough to
cover the continental U.S. to a depth of 9.5 feet.
- Nearly 40 million North Americans live on these lakes and drink their waters, and countless
others enjoy their beauty.
- The Great Lakes cover an area of 94,000 square miles.
- The Great Lakes contain over 10,000 miles of coastline.
- The Great Lakes represent a 1200 mile shipping route.
- Due to varying topography, the hydrologic conditions in the Lakes are also very different with
water retention times ranging from 3 years for Lake Erie to 187 years for Lake Superior. These
long retention times have serious implications for the accumulation of contaminants.
- Some of the world's largest sea going ships ply these waters, and the fury of their storms is
legendary. History lines the lakes' bottoms with one of the highest densities of shipwrecks in
the world and the lakes continue to claim victims even today.
Issues Facing the Region
Water Pollution
Despite their sheer volume, the Great Lakes are not without problems. In 1993, more than 400,000 of
Milwaukee's citizens suffered illness as a result of the contamination of the water supply by the
intestinal parasite, Cryptosporidium - the largest single water borne disease outbreak in the history
of the U.S. The most severely affected were the poor and minority communities. The U.S.- Canadian
International Joint Commission (IJC) has identified 43 "Areas of Concern" around the Great
Lakes - environments in which pollution currently is severe enough to run a substantial risk to human
and wildlife health. The cost of clean-up represents a major regional problem running to billions of
dollars that augurs to stifle urban revitalization, resource stewardship, and industrial growth. At
the same time the relative risks associated with alternative remediation strategies are poorly
quantified due principally to a lack of science.
Global Climate Change
Despite their size and dynamics, these lakes are surprisingly fragile systems. Global warming models
predict large scale alterations in global meteorological patterns, particularly in temperate and high
latitudes where shifts in the timing and magnitude of precipitation of 20 percent are possible. Such
changes could have significant impacts on agriculture and food production in the U.S. Corn Belt and
on the Great Lakes that are particularly sensitive to alterations in heat and precipitation fluxes.
Invasive Species
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Zebra Mussels fouling a shipwreck
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Exotic species invasions into this evolutionarily
young system have a long history of disrupting ecosystems, altering biological diversity, and
changing the key pathways in important biogeochemical cycles. These changes have had major resource
management consequences, with concomitant economic losses and deteriorations in ecosystem health.
Tourism, Recreational Fishing
The lakes support a $4 billion a year recreational fishery industry, a multi-billion dollar a year
tourism economy.
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