The Great Lakes from space
The Great Lakes are a group of five large lakes on or near the United States-Canadian border. They are the largest group of fresh water lakes on the earth, and the Great Lakes-St. Lawrence system is the largest fresh-water system in the world. They are sometimes referred to as inland seas.
The Great Lakes are (west to east, general direction of water flow):
A commonly used mnemonic for remembering the names of the lakes is HOMES, for Huron, Ontario, Michigan, Erie, and Superior, although this mnemonic puts the lakes in no particular order. Alternative mnemonics such as Sister Mary Hates Ecumenical Overtures or She Made Harry Eat Onions place them in west-east order.
A much smaller sixth lake, Lake St. Clair, is part of the Great Lakes system between Lake Huron and Lake Erie, but is not considered one of the "Great Lakes". The system also includes the rivers that connect the lakes: St. Mary's River between Lake Superior and Lake Huron, the St. Clair River between Lake Huron and Lake St. Clair, the Detroit River between Lake St. Clair and Lake Erie, and the Niagara River and Niagara Falls, between Lake Erie and Lake Ontario. (Lake Michigan is connected to Lake Huron through the Straits of Mackinac.) Large islands and a peninsula divide Lake Huron into the lake proper and Georgian Bay.
The lakes are bounded by Ontario (all of the lakes but Michigan), Minnesota, Wisconsin, Michigan (all but Ontario), Illinois, Indiana, Ohio, Pennsylvania, and New York. Four of the five lakes straddle the U.S.-Canada border; the fifth, Lake Michigan, is entirely within the United States. The Saint Lawrence River, which marks the same international border for a portion of its course, is a primary outlet of these interconnected lakes, and flows through Quebec and past the Gaspé Peninsula to the northern Atlantic Ocean.
The Great Lakes are clearly visible in this satellite image of North America
Sprinkled throughout the lakes are the approximately 35,000 Great Lakes islands, including Manitoulin Island in Lake Huron, the largest island in any inland body of water, and Isle Royale in Lake Superior, the largest island in the largest lake (each island large enough to itself contain multiple lakes).
The Saint Lawrence Seaway and Great Lakes Waterway opened the Great Lakes to ocean-going vessels. However the move to wider ocean-going container ships - which do not fit through the locks on these routes - has limited shipping on the lakes. Despite their vast size, large sections of the Great Lakes freeze over in winter, and most shipping stops during that season. There are some icebreakers that operate on the lakes.
The lakes have an effect on weather in the region, known as lake effect. In winter, the moisture picked up by the prevailing winds from the west can produce very heavy snowfall, especially along lakeshores to the east such as in Michigan, Ontario, and New York. The most infamous example is the Blizzard of '77 in which previous heavy snowfall and strong winds running the length of Lake Erie covered Buffalo, New York in drifting snow. The lakes also moderate seasonal temperatures somewhat, by absorbing heat and cooling the air in summer, then slowly radiating that heat in autumn. This temperature buffering produces areas known as "fruit belts", where fruit typically grown farther south can be produced in commercial quantities.
Relative elevations, average depths, maximum depths, and volumes of the Great Lakes.
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Period = from:-1000 till:600 TimeAxis = orientation:vertical ScaleMajor = unit:year increment:500 start:-1000 ScaleMinor = unit:year increment:100 start:-1000
Define $elevation = shift:(0,15) mark:(line,textoutsidebar) textcolor:textoutsidebar Define $avgdepth = mark:(line,textinbar) textcolor:textinbar Define $maxdepth = shift:(0,-11) mark:(line,textoutsidebar) textcolor:textoutsidebar
bar:Superior from:-732 till:600 width:194 color:blue1
$elevation at:600 text:"600 ft~(183 m)"
$avgdepth at:117 shift:(0,1) text:"483 ft (147 m)"
$maxdepth at:-732 text:"1332 ft (406 m)"
bar:Michigan from:-348 till:577 width:113 color:blue5
$elevation at:577 text:"577 ft~(176 m)"
$avgdepth at:298 shift:(0,2) text:"279 ft~(85 m)"
$maxdepth at:-348 text:"925 ft (282 m)"
bar:Huron from:-173 till:577 width:101 color:blue3
$elevation at:577 text:"577 ft~(176 m)"
$avgdepth at:382 shift:(0,1) text:"195 ft (59 m)"
$maxdepth at:-173 text:"750 ft (229 m)"
bar:Erie from:359 till:569 width:49 color:blue2
$elevation at:569 text:"569 ft~(173 m)"
$avgdepth at:507 align:left shift:(30,2) textcolor:textoutsidebar text:"62 ft (19 m)"
$maxdepth at:359 text:"210 ft~(64 m)"
bar:Ontario from:-559 till:243 width:44 color:blue4
$elevation at:243 text:"243 ft~(74 m)"
$avgdepth at:-40 shift:(0,2) text:"283 ft~(86 m)"
$maxdepth at:-559 text:"802 ft~(244 m)"
align:left shift:(35,0) textcolor:green
||The volume of each rectangle is proportionate to the volume of each lake. All measurements at Low Water Datum.
EPA's Great Lakes Atlas: Factsheet #1.
The Great Lakes were formed at the end of the last ice age, about 10,000 years ago, when the Laurentide Glaciation receded. When this happened, the giant glacier scratched a deep hole within the Earth's surface. The melting also left behind a large amount of meltwater (see Lake Agassiz) which filled up these holes, which were soon to become the Great Lakes. Because of the uneven nature of glacier erosion, some higher hills became Great Lakes islands. The Niagara Escarpment follows the contour of the Great Lakes between New York and Wisconsin -- Herbert Simon called this escarpment the spinal cord of my native land.
Economy of the Great Lakes
The lakes are extensively used for transport, though cargo traffic has decreased considerably in recent years. Storms and reefs are a common threat, and many thousands of ships have sunk in these waters, the number estimates varying widely. The SS Edmund Fitzgerald was the last major freighter lost on the lakes. The Great Lakes Waterway makes each of the lakes accessible.
Evolution of shipping
During settlement, the Great Lakes and its rivers were the only practical means of moving people and freight. Anything and everything floated on the lakes. Some ended up on the bottom due to storms, fires, collisions and underwater hazards. (See Edmund Fitzgerald and Le Griffon.) Barges from middle North America were able to reach the Atlantic Ocean from the Great Lakes when the Erie Canal opened in 1825.
The main business of many of the passenger lines in the 1800s was transporting immigrants. Many of the larger cities owe their existence to their position on the lakes as a freight destination as well as for being a magnet for immigrants. After railroads and surface roads developed the freight and passenger businesses dwindled and, excepting ferries and a few foreign cruise ships, now has vanished.
Yet, the immigration routes still have an effect today. Immigrants often formed their own communities and some areas have a pronounced ethnicity, say Dutch, German, Polish or Finnish, among many others. Since many immigrants settled for a time in New England before moving westward, many areas on the U.S. side of the Great Lakes also have a New England feel, especially in home styles and accent.
Since general freight these days is transported by railroads and trucks (lorries), domestic ships mostly move bulk cargoes, such as iron ore and its derivatives, coal and limestone for the steel industry. The domestic bulk freight developed because of the nearby mines. It was more economical to transport the ingredients for steel to centralized plants rather than try to make steel on the spot. Ingredients for steel, however, are not the only bulk shipments made.
Because the lake maritime community largely developed independently, it has its own language. Ships, no matter the size, are referred to as boats. When the sailing ships gave way to steamships, they were called steamboats—the same term used on the Mississippi. The ships also have a distinctive design. Ships that primarily trade on the lakes are known as lakers. Foreign boats are known as salties.
One of the more common sights on the lakes is the 1,000 by 105-foot, 60,000-ton (U.S. long ton) self-unloader. This is a laker with a huge conveyor belt system that can unload itself by swinging a crane over the side. Understandably, because most things go by land and the fact that one modern ship is the equivalent of many older ships, the Great Lakes fleet is a fraction of what it once was.
The Great Lakes are used as a major mode of transport for bulk goods. The brigantine Le Griffon, which was commissioned by René Robert Cavelier, Sieur de La Salle, was towed to the southern end of the Niagara River, to become the first sailing ship to travel the upper Great Lakes on August 7, 1679.
In 2002, 162 million net tons of dry bulk cargo was moved on the Lakes. This was, in order of volume: iron ore, coal, stone, grain, salt, cement and potash. The iron ore and much of the stone and coal are used in the steel industry. There is also some shipping of liquid and containerized cargo but most container ships cannot pass the locks on the Saint Lawrence Seaway because they are too wide. The total amount of shipping on the lakes has been on a downward trend for several years.
Recreational boating and tourism are major industries on the Great Lakes. A few small cruise ships operate on the Great Lakes including a couple of sailing ships. Sport fishing, commercial fishing, and Native American fishing represent a 4 billion dollar (USD) a year industry with salmon, whitefish, smelt, lake trout, and walleye being major catches.
The Great Lakes are used to supply drinking water to tens of millions of people in bordering areas. This valuable resource is collectively administered by the state and provincial governments adjacent to the lakes.
Several ferries operate on the Great Lakes to carry passengers to various islands, including Isle Royale, Pelee Island, Mackinac Island, Beaver Island, both Bois Blanc Islands, Kellys Island , South Bass Island , North Manitou Island, South Manitou Island, Harsens Island , Manitoulin Island, and the Toronto Islands. As of 2005, three car ferry services cross the Great Lakes: a steamer across Lake Michigan from Ludington, Michigan to Manitowoc, Wisconsin; a high speed catamaran on a second Lake Michigan route from Milwaukee, Wisconsin to Muskegon, Michigan; and an international ferry across Lake Ontario from Rochester, New York to Toronto, Ontario.
The International Joint Commission was established in 1909 to help prevent and resolve disputes relating to the use and quality of boundary waters and to advise Canada and the United States on questions related to water resources. Concerns over diversion of Lake water are of concern to both Americans and Canadians. Some water is diverted through the Chicago River to operate the Illinois Waterway but the flow is limited by treaty. Possible schemes for bottled water plants and diversion to dry regions of the continent raise concerns. Under the U.S. "Water Resources Development Act", diversions of water from the Great Lakes basin requires the approval of all eight Great Lakes governors, which rarely occurs. International treaties regulate large diversions. In 1998, a Canadian company won Canadian approval to annually withdraw 158 million gallons of Lake Superior water to ship by tanker to drought-stricken Asian countries. Public outcry forced the abandonment of the plan before it began.
The Rush-Bagot Agreement of 1817 limits the number of armed vessels permitted on the Great Lakes. Some are wondering if this agreement will survive the aftermath of September 11, 2001.
Lake Champlain in upstate New York briefly became the sixth "Great Lake of the United States" on March 6, 1998, when President Clinton signed Senate Bill 927. This bill, which reauthorized the Sea Grant Program , contained a line penned by Senator Patrick Leahy (D-VT) declaring Lake Champlain to be a Great Lake. Not coincidentally, this status allows neighboring states to apply for additional federal research and education funds allocated to these national resources. Following a small uproar (and several New York Times articles), the Great Lake status was rescinded (although Vermont universities continue to receive funds to monitor and study the lake.)
Great Lakes Ecological Challenges
The Lakes plentifully provided fish to the Native groups who lived near them or upon their shores. Early European settlers were astounded by both the variety and numbers of fish. Historically, fish populations were the early indicator of the condition of the Lakes, and have remained one of the key indicators even in our technological era of sophisticated analyses and measuring instruments. According to the bi-national (U.S. and Canadian) resource book, The Great Lakes: An Environmental Atlas and Resource Book, "the largest Great Lakes fish harvests were recorded in 1889 and 1899 at some 67,000 tonnes (147 million pounds)," though the beginning of environmental impacts on the fish can be traced back nearly a century prior to those years.
By 1801, New York legislators found it necessary to pass regulations curtailing obstructions to the natural migrations of Atlantic salmon from Lake Erie into their spawning channels. In the early nineteenth century, Upper Canada’s government found it necessary to introduce similar legislation prohibiting the use of weirs, nets, etc. at the mouths of Lake Ontario’s tributary watercourses. Other protective legislation was passed, as well, but enforcement remained difficult and often quite spotty.
On both sides of the U.S.-Canada border, the proliferation of dams and impoundments multiplied, necessitating more regulatory efforts. The decline in fish populations was unmistakable by the middle of the nineteenth century. The decline in salmon was recognized by Canadian officials and reported as virtually a complete absence by the end of the 1860s, the Wisconsin Fisheries Commission noted a reduction of roughly a quarter in general fish harvests by 1875.
Overfishing was cited as responsible for the decline of the population of various whitefish, important due to their culinary desirability and, hence, economic consequence. Moreover, between 1879 and 1899, reported whitefish harvests declined from some 24.3 million to just over 9 million. Recorded sturgeon catches fell from 7.8 million pounds in 1879 to 1.7 million in 1899.
There were, however, other factors in the declines besides overfishing and the problems posed by dams and other obstructions. Logging in the region removed tree cover near stream channels, which provide spawning grounds, and this affected necessary shade and temperature-moderating conditions. Removal of tree cover also destabilized soil, allowing soil to be carried in greater quantity into the streambeds, and even brought about more frequent flooding. Running cut logs down the Lakes’ tributary rivers also stirred bottom sediments. In 1884, the New York Fish Commission determined that the dumping of sawmill waste (e.g., chips and sawdust) was impacting Lakes fish populations.
The Great Lakes are international, and in situations that require regulation, a lack of cooperation between the U.S. and Canada might be predicted to have disastrous consequences. In the development of ecological problems in the Great Lakes, it was the influx of parasitic lamprey populations after the development of the Erie Canal and the much later Welland Canal that led to the two federal governments attempting to work together – which proved a very complicated and troubled road.
Nevertheless, despite the ever more sophisticated efforts to eliminate or minimize the lamprey, by the mid 1950s Lake Michigan and Huron’s lake trout populations were reduced by about 99%, with the lamprey deemed largely to blame. A result was the bi-national Great Lakes Fishery Commission.
Other ecological problems in the Lakes and their surrounds have stemmed from urban sprawl, sewage disposal, and toxic industrial effluent. These, of course, also affect aquatic food chains and fish populations. Some of these glaring problem areas are what attracted the high-level publicity of Great Lakes ecological troubles in the 1960s and 1970s. Evidence of chemical pollution in the Lakes and their tributaries now stretches back for decades. In the late 1960s, the recurrent phenomenon of the surface of river stretches (e.g., Ohio’s Cuyahoga River) catching fire, due to a combination of oil, chemicals, and combustible materials floating on the water’s surface, came to the attention of a public growing more environmentally aware. Another aspect that caught popular attention was the “toxic blobs” (expanses of lake bed coveredby various combinations of such substances as solvents, wood preservatives, coal tar, and metals) found in Lake Superior, the St. Clair River, and other portions of the Great Lakes region.
According to the authoritative bi-national source The Great Lakes: An Environmental Atlas and Resource Book, "Only pockets remain of the once large commercial fishery."
- Pre-European History of the Lakes
- European History of the Lakes
- Great Lakes Ecology
- Culture of the Great Lakes
See also: Frontenac (the first steamer on the lakes, launched June 5, 1817).
Last updated: 10-19-2005 15:17:09