Great Lakes Forever c/o Biodiversity Project 4507 N Ravenswood #106 Chicago, IL 60640 773-496-4020 phone 773-906-1303 fax project@biodiverse.org   Intro :: Environment :: Cultural History :: Economy :: Policy :: Fun Facts Fun Facts The Great Lakes are the largest group of freshwater lakes in the world, stretching more than 90 thousand square miles and covering an area larger than Minnesota or New Brunswick, Nova Scotia and Prince Edward Island combined. Recognizing the Great Lakes’ great size and the important role they have played as the transportation hub of eastern North America, sailors and landlubbers alike have alternatively christened the Lakes the “sweet water” and “inland seas,” and “America’s fourth sea coast.” The Great Lakes are an international treasure, containing 18% of the entire world’s fresh surface water supply. The water in the Great Lakes is constantly changing: water that evaporates from the Lakes surface and flows to the Atlantic Ocean is replenished by rain, snow and surface runoff. But only 1% of Great Lakes water changes over each year. The remaining volume is effectively a gift of the last ice age, deposited as the glaciers retreated over 10,000 years ago. Why does this put Great Lakes water at risk? Lake Superior is the largest and deepest of the Great Lakes, covering over 31,700 square miles, holding 3.2 quadrillion gallons of water and reaching depths of 1,332 feet. Because of its size and the slowness of its outflow (only a half of a percent flows from Lake Superior to Lakes Huron and Michigan each year), Lake Superior has a very long retention time - it takes nearly two centuries for a drop of rain to cycle through Lake Superior. In addition to being the largest and deepest of the Great Lakes, Lake Superior is the most remote. Its surrounding land is the most heavily forested (over 90% of the Superior drainage basin is covered with forest) and sparsely populated (less than 2% of the Great Lakes basin’s population lives in the Superior basin) of the Great Lakes. What does this have to do with mercury, PCBs and other toxic pollutants? Lake Erie is the smallest and shallowest of the Great Lakes, holding only 4% of Lake Superior’s volume and sporting an average depth of only 62 feet. Lake Erie’s surrounding land is also the most heavily populated (seventeen metropolitan areas have populations over 50,000) and intensively farmed (over 2/3 of the Lake Erie drainage basin is in agricultural use). What does this have to do with algae blooms and fish kills? Fishing is a mainstay of the Great Lakes’ cultures and economy. In 1996, 2 million anglers enjoyed fishing the Great Lakes. That same year, the commercial fish harvest for the entire Great Lakes basin was 63 million pounds. The commercial and sport fishery on the Great Lakes is collectively valued at more than $4 billion annually! How could Great Lakes fisheries be at risk? Nicknamed America’s fourth sea-coast, the Great Lakes and their connecting channels played an important role in the history of North American transportation. With the construction of the Erie, Lachine and Welland Canals in the 1820s, as well as canals to link the Great Lakes to the Ohio and Mississippi Rivers, the Great Lakes became the hub of transportation in eastern Northern America. Today, roughly 300 million tons – mostly coal, iron ore and grain – are shipped out of major ports in the United States alone! Who’s been taking advantage of the shipping industry? Chicago 's Grant Park is built on a foundation of debris from the Great Chicago Fire that was dumped into Lake Michigan in the 1870's. Businessman Aaron Montgomery Ward sued the city to protect the shoreline from development. Supporting lakeshore protection in 1909, Daniel H. Burnham said, “The lake is living water . . . Not a foot of its shores should be appropriated by individuals to the exclusion of the people.” The Great Lakes are a special place we all enjoy. Their shorelines are dotted by 10 national parks and lakeshores, and hundreds of state and provincial parks. Over 70 million people visit these parks annually. Why are some park visitors disappointed? Not So Fun Facts Each year, nearly 157 billion gallons of water is permanently lost from the Great Lakes drainage basin (the surrounding land and waterways that drain water to the Lakes). That’s more than 4,000 gallons for every one of the basin's 37 million residents! As shocking as current withdrawal levels may seem, they’re but a fraction of what we could soon lose. Everyone who lives in the Great Lakes drainage basin relies on the Lakes for their drinking water. Twenty-six million residents use water withdrawn directly from the Lakes, while 11 million intercept Great Lakes groundwater as it drains to basin tributaries and the Lakes themselves. With demand for fresh water increasing across the country and the world, special interests are pushing to actually buy and sell Great Lakes water for a profit.Read more about Great Lakes water supply. Although Lake Superior is the most remote of the Great Lakes, it is far from immune to the threats of pollution we commonly associate with the more populous and developed Lakes Michigan, Erie and Ontario. Lake Superior, because of it’s large surface area, is particularly susceptible to airborne pollution, including mercury-laden smoke from coal-burning power plants and agricultural pesticides carried by winds from places as distant as Georgia and other southeastern states. This problem is exacerbated by Lake Superior’s long retention time (how long a drop of water stays in Lake Superior before flowing on to Lakes Michigan and Huron). While Lake Superior currently has lower levels of mercury, PCBs and other toxics harmful to wildlife and human health than any other Great Lake, it “holds on” to dissolved pollutants for a longer period, allowing them to build to much higher concentrations. Read more about Great Lakes water quality. Of all the Great Lakes, Lake Erie is the most susceptible to eutrophication and the presence of “dead zones”. Due to the heavy urbanization and agricultural use of its surrounding lands, Lake Erie is bombarded by massive amounts of untreated sewage dumping from cities and livestock facilities, as well as polluted runoff contaminated by failing septic systems, excess lawn fertilizers and pet feces. This increased organic matter and the abundance of light in Erie’s shallow depths encourages rapid plant growth. Once those plants die and begin decomposing, they use up all available oxygen. The result is “dead zone” where little if any life can survive. Read more about Great Lakes water quality. Today’s commercial fishery harvest of 63 million pounds may seem large, but peak harvests were achieved in the late 19th century at 147 million pounds! Initial harvest declines were largely due to over fishing, but habitat destruction and invasive species are the greatest challenges of today. More than two-thirds of Great Lakes fish species spawn in wetlands, and many rely on near shore vegetation for food and shelter. Wide-spread alteration and destruction of these habitats – including 75% of Great Lakes shoreline and 2/3 of the region’s wetlands – harms native fish. Read more about habitat protection. Since the 1800s, more than 160 aquatic invasive species have become established in the Great Lakes. These invaders include the sea lamprey, zebra mussel, round goby, quagga mussel and spiny water flea, and often infiltrate the Great Lakes via shipping canals and transoceanic vessels. Invasive species threaten the survival of our native fish, wildlife and plants and upset the balance of the Great Lakes ecosystem. The effects of such invasives can be drastic, as in the early 1900s when the sea lamprey was first introduced to the upper four Great Lakes. Within roughly 20 years, Lake Michigan’s lake trout population had declined by 95%, a loss from which it has not yet recovered today. Read more about Great Lakes invasive species. Today, the greatest source of invasive species - such as the zebra mussel and spiny water flea - in the Lakes is ship ballast water. Cargo ships that carry millions of tons of goods to and from Great Lakes ports every year rely on “ballast water” to help stabilize their ships on the seas. When these ships pick up new cargo, they can dump tens of thousands of gallons of ballast water – often taken from distant seas – into the Great Lakes. In 2002, 23% of Great Lakes beaches were closed for at least a day – and 14% were closed for more than 9 days – to prevent the spread of waterborne disease. Bacterial and viral pathogens are introduced to the Great Lakes from overflowing sewage plants and polluted runoff from our yards, streets and farms. Read more about Great Lakes water quality.