The Great LakesMichael W. Rowan, Ph.D.

The Great Lakes

• Began to form ~500,000 years ago• Took present shape ~10,000 years ago• Watershed area = 196,000 sq. miles

– 34 million people (27.5 million U.S., 6.4 million Canada)

• Water surface area = 94,700 sq. miles• U.S. Great Lakes shoreline > U.S. east

coast shoreline

Unique ecosystem, and unique resources

• Largest surface freshwater system on earth

• Contains 84% of North America’s surface freshwater

• Contains 21% of the world’s surface freshwater

Characteristic Superior Michigan Huron Erie Ontario

Length (miles) 350 307 206 241 193

Width (miles) 160 118 183 57 53

Depth, Average & Max. (feet) 489 / 1,333 279 / 923 195 / 750 62 / 210 283/802

Volume (cubic miles) 2,935 1,180 849 116 393

Surface Area (sq. miles) 31,700 22,300 23,000 9,910 7,340

Drainage Basin Area (sq.miles) 49,300 45,600 50,700 22,700 23,400

Shoreline (miles) 2,730 1,640 3,830 871 712

Elevation (feet) 601 577 577 569 243

Outlets

St. Mary's River

Mackinac Straits

St. Clair River Niagara Falls St. Lawrence River

Chicago River Welland Canal

Water Replacement Time (yrs) 173 62 21 2.7 6

Human Population 672,116 12,052,743 2,960,359 12,532,977 5,692,178

Source:   Sea Grant and MSU Extension, 2000

Great Lakes Environmental Issues

• Invasive species• Nonpoint source pollution• Urban sprawl• Mercury in fish• Contaminated sediments (dredging?)• Nutrient loading• Water diversion• Climate change• Endocrine disrupters• Atmospheric deposition

Erie – Our Great Lake

• Smallest in volume, depth, retention time, watershed area

• Largest human population• Warmest, most nutrient-rich, and most

productive• Fishery is more productive than the

fisheries of other four Great Lakes combined

• Largest percentage of land in agriculture

Cuyahoga River FireNovember 1952

Brown Bullhead (Ameiurus nebulosus)

• Ubiquitous benthic catfish distributed throughout the great lakes

• Vulnerable to many hydrophobic contaminants (PAHs)

• Sediment PAHs linked to high tumor rates and changes in blood variables

Tri-C Eastern Campus BIO 2806 - Environmental Science for Educators: Promoting Watershed Stewardship July 2007

BROWN BULLHEAD (Ameiurus nebulosus)

Tri-C Eastern Campus BIO 2806 - Environmental Science for Educators: Promoting Watershed Stewardship July 2008

Something Fishy

• 34 species of Lake Erie Fish are rare, threatened, or endangered

• Blue pike – extinct• Lake sturgeon, brook trout, lake

trout, . . . • Fish consumption advisories due

to mercury and PCBs

CREDITS

• Thanks to Michael Rowan, PhD from Tri-C East who donated his Power Point slides so graciously.

• Course: “Promoting Watershed Stewardship” for Environmental Science Educators

Educator Resources

• Great Lakes Environmental Atlas - USEPA• Great Lakes science activities – OSU/Ohio

Sea Grant• NASA - Visible Earth – satellite images of

the Great Lakes– Animation: lake effect snow

• Great Lakes Commission• International Joint Commisison• Great Lakes Information Network• Lake Erie: Beyond the Surface -Channel 3