Great Lakes

Satellite image of the Great Lakes, April 24, 2000
Terra MODIS image of the Great Lakes, January 27, 2005, showing ice beginning to build up around the shores of each of the lakes, with snow on the ground.
Location in North America

The Great Lakes (French: les Grands-Lacs), also called the Laurentian Great Lakes[1] and the Great Lakes of North America, are a series of interconnected freshwater lakes located primarily in the upper mid-east region of North America, on the Canada–United States border, which connect to the Atlantic Ocean through the Saint Lawrence River. They consist of Lakes Superior, Michigan, Huron, Erie, and Ontario, although hydrologically, there are four lakes, Superior, Erie, Ontario, and Michigan-Huron. The lakes are interconnected by the Great Lakes Waterway.

The Great Lakes are the largest group of freshwater lakes on Earth by total area, and second largest by total volume, containing 21% of the world's surface fresh water by volume.[2][3][4] The total surface is 94,250 square miles (244,106 km2), and the total volume (measured at the low water datum) is 5,439 cubic miles (22,671 km3),[5] slightly less than the volume of Lake Baikal (23,615 km³, 22–23% of the world's surface fresh water). Due to their sea-like characteristics (rolling waves, sustained winds, strong currents, great depths, and distant horizons) the five Great Lakes have also long been referred to as inland seas.[6] Not counting Lake Michigan-Huron, Lake Superior is the second largest lake in the world by area, and the largest freshwater lake by area. Lake Michigan is the largest lake that is entirely within one country.[7][8][9][10]

The Great Lakes began to form at the end of the last glacial period around 14,000 years ago, as retreating ice sheets exposed the basins they had carved into the land which then filled with meltwater.[11] The lakes have been a major source for transportation, migration, trade, and fishing, serving as a habitat to a large number of aquatic species in a region with much biodiversity.

The surrounding region is called the Great Lakes region, which includes the Great Lakes Megalopolis.[12]

Geography

A map of the Great Lakes Basin showing the five sub-basins within. Left to right they are: Superior, including Nipigon's basin, (magenta); Michigan (cyan); Huron (pale green); Erie (yellow); Ontario (light coral).

Though the five lakes lie in separate basins, they form a single, naturally interconnected body of fresh water, within the Great Lakes Basin. They form a chain connecting the east-central interior of North America to the Atlantic Ocean. From the interior to the outlet at the Saint Lawrence River, water flows from Superior to Huron and Michigan, southward to Erie, and finally northward to Lake Ontario. The lakes drain a large watershed via many rivers, and are studded with approximately 35,000 islands.[13] There are also several thousand smaller lakes, often called "inland lakes," within the basin.[14] The surface area of the five primary lakes combined is roughly equal to the size of the United Kingdom, while the surface area of the entire basin (the lakes and the land they drain) is about the size of the UK and France combined.[15] Lake Michigan is the only one of the Great Lakes that is located entirely within the United States; the others form a water boundary between the United States and Canada. The lakes are divided among the jurisdictions of the Canadian province of Ontario and the U.S. states of Michigan, Wisconsin, Minnesota, Illinois, Indiana, Ohio, Pennsylvania, and New York. Both Ontario and Michigan include in their boundaries portions of four of the lakes: Ontario does not border Lake Michigan, and Michigan does not border Lake Ontario. New York and Wisconsin's jurisdictions extend into two lakes, and each of the remaining states into one of the lakes.

Bathymetry

Lake Erie Lake Huron Lake Michigan Lake Ontario Lake Superior
Surface area[5] 9,910 sq mi (25,700 km2) 23,000 sq mi (60,000 km2) 22,300 sq mi (58,000 km2) 7,340 sq mi (19,000 km2) 31,700 sq mi (82,000 km2)
Water volume[5] 116 cu mi (480 km3) 850 cu mi (3,500 km3) 1,180 cu mi (4,900 km3) 393 cu mi (1,640 km3) 2,900 cu mi (12,000 km3)
Elevation[16] 571 ft (174 m) 577 ft (176 m) 577 ft (176 m) 246 ft (75 m) 600.0 ft (182.9 m)
Average depth[15] 62 ft (19 m) 195 ft (59 m) 279 ft (85 m) 283 ft (86 m) 483 ft (147 m)
Maximum depth[17] 210 ft (64 m) 748 ft (228 m) 925 ft (282 m) 804 ft (245 m) 1,333 ft (406 m)
Major settlements[18] Buffalo, NY
Erie, PA
Cleveland, OH
Lorain, OH
Toledo, OH
Sandusky, OH
Alpena, MI
Bay City, MI
Owen Sound, ON
Port Huron, MI
Sarnia, ON
Chicago, IL
Gary, IN
Green Bay, WI
Sheboygan, WI
Milwaukee, WI
Kenosha, WI
Racine, WI
Muskegon, MI
Traverse City, MI
Hamilton, ON
Kingston, ON
Mississauga, ON
Oshawa, ON
Rochester, NY
Toronto, ON
Duluth, MN
Marquette, MI
Sault Ste. Marie, MI
Sault Ste. Marie, ON
Superior, WI
Thunder Bay, ON
Relative elevations, average depths, maximum depths, and volumes of the Great Lakes.
Notes: The area of each rectangle is proportionate to the volume of each lake. All measurements at Low Water Datum.
Source: EPA[16]
System profile of the Great Lakes.

As the surfaces of Lakes Superior, Huron, Michigan, and Erie are all approximately the same elevation above sea level, while Lake Ontario is significantly lower, and because the Niagara Escarpment precludes all natural navigation, the four upper lakes are commonly called the "upper great lakes". This designation, however, is not universal. Those living on the shore of Lake Superior often refer to all the other lakes as "the lower lakes", because they are farther south. Sailors of bulk freighters transferring cargoes from Lake Superior and northern Lake Michigan and Lake Huron to ports on Lake Erie or Ontario commonly refer to the latter as the lower lakes and Lakes Michigan, Huron, and Superior as the upper lakes. This corresponds to thinking of Lakes Erie and Ontario as "down south" and the others as "up north". Vessels sailing north on Lake Michigan are considered "upbound" even though they are sailing toward its effluent current.[25]

Primary connecting waterways

Chicago on Lake Michigan is in the western part of the lakes megalopolis, and the site of the waterway linking the lakes to the Mississippi River valley
Detroit on the Detroit River links the region's central metropolitan areas.
Toronto on Lake Ontario is in the eastern section of the Great Lakes Megalopolis

Lake Michigan–Huron

Lakes Huron and Michigan are sometimes considered a single lake, called Lake Michigan–Huron, because they are one hydrological body of water connected by the Straits of Mackinac.[26] The straits are 5 miles (8 km) wide[15] and 120 feet (37 m) deep; the water levels – currently at 577 feet (176 m) – rise and fall together,[27] and the flow between Michigan and Huron frequently reverses direction.

Other significant bodies of water

Islands

South Bass Island in Lake Erie

Dispersed throughout the Great Lakes are approximately 35,000 islands.[13] The largest among them is Manitoulin Island in Lake Huron, the largest island in any inland body of water in the world.[34] The second-largest island is Isle Royale in Lake Superior.[35] Both of these islands are large enough to contain multiple lakes themselves—for instance, Manitoulin Island's Lake Manitou is the world's largest lake located on a freshwater island.[36] Some of these lakes even have their own islands, like Treasure Island in Lake Mindemoya in Manitoulin Island

Peninsulas

The Great Lakes also have several peninsulas between them, including the Door Peninsula, the Peninsulas of Michigan, and the Ontario Peninsula. Some of these peninsulas even contain smaller peninsulas, like the Keweenaw Peninsula, the Thumb Peninsula, the Bruce Peninsula, and the Niagara Peninsula. Population centers on the peninsulas include Grand Rapids, Michigan, Detroit, Michigan, London, Ontario, Hamilton, Ontario, and Toronto, Ontario.

Shipping connection to the ocean

The Saint Lawrence Seaway and Great Lakes Waterway make the Great Lakes accessible to ocean-going vessels.[37] However, shifts in shipping to wider ocean-going container ships—which do not fit through the locks on these routes—have limited container shipping on the lakes. Most Great Lakes trade is of bulk material, and bulk freighters of Seawaymax-size or less can move throughout the entire lakes and out to the Atlantic.[38] Larger ships are confined to working in the lakes themselves. Only barges can access the Illinois Waterway system providing access to the Gulf of Mexico via the Mississippi River. Despite their vast size, large sections of the Great Lakes freeze over in winter, interrupting most shipping from January to March. Some icebreakers ply the lakes, keeping the shipping lanes open through other periods of ice on the lakes.

The Great Lakes are also connected by the Chicago Sanitary and Ship Canal to the Gulf of Mexico by way of the Illinois River (from the Chicago River) and the Mississippi River. An alternate track is via the Illinois River (from Chicago), to the Mississippi, up the Ohio, and then through the Tennessee–Tombigbee Waterway (a combination of a series of rivers and lakes and canals), to Mobile Bay and the Gulf of Mexico. Commercial tug-and-barge traffic on these waterways is heavy.[39]

Pleasure boats can also enter or exit the Great Lakes by way of the Erie Canal and Hudson River in New York. The Erie Canal connects to the Great Lakes at the east end of Lake Erie (at Buffalo, New York) and at the south side of Lake Ontario (at Oswego, New York).

Water levels

In 2009, the lakes contained 84% of the surface freshwater of North America;[40] if the water were evenly distributed over the entire continent's land area, it would reach a depth of 1.5 meters (5 feet).[15] The source of water levels in the lakes is tied to what was left by melting glaciers when the lakes took their present form. Annually, only about 1% is "new" water originating from rivers, precipitation, and groundwater springs that drain into the lakes. Historically, evaporation has been balanced by drainage, making the level of the lakes constant.[15] While the lake levels have been preserved, intensive human population growth only began in the region in the 20th century and continues today.[15] At least two human water use activities have been identified as having the potential to affect the lakes' levels: diversion (the transfer of water to other watersheds) and consumption (substantially done today by the use of lake water to power and cool electric generation plants, resulting in evaporation).[41]

The water level of Lake Michigan–Huron had remained fairly constant over the 20th century,[42] but has nevertheless dropped more than 6 feet from the record high in 1986 to the low of 2013.[43] One newspaper reported that the long-term average level has gone down about 20 inches because of dredging and subsequent erosion in the St. Clair River. Lake Michigan–Huron hit all-time record low levels in 2013; according to the US Army Corps of Engineers, the previous record low had been set in 1964.[43] By April 2015 the water level had recovered to 7 inches (17.5 cm) more than the "long term monthly average".[44]

Other Languages
Afrikaans: Groot Mere
Alemannisch: Große Seen
asturianu: Grandes Llagos
azərbaycanca: Böyük göllər
Bân-lâm-gú: Gō͘-toā-ô͘
башҡортса: Бөйөк күлдәр
беларуская: Вялікія азёры
беларуская (тарашкевіца)‎: Вялікія азёры
भोजपुरी: ग्रेट लेक्स
български: Големите езера
Boarisch: Grousse Seen
bosanski: Velika jezera
Чӑвашла: Мăн кӳлĕсем
čeština: Velká jezera
Deutsch: Große Seen
Ελληνικά: Μεγάλες Λίμνες
emiliàn e rumagnòl: Lèg grand
Fiji Hindi: Great Lakes
føroyskt: Stóruvøtn
한국어: 오대호
հայերեն: Մեծ Լճեր
hornjoserbsce: Wulke jězory
hrvatski: Velika jezera
Bahasa Indonesia: Danau-Danau Besar (Amerika)
íslenska: Vötnin miklu
ქართული: დიდი ტბები
қазақша: Ұлы көлдер
kurdî: Golên Mezin
Кыргызча: Улуу көлдөр
Latina: Lacus Magni
latviešu: Lielie ezeri
lietuvių: Didieji ežerai
Lingua Franca Nova: Lagos Grande
la .lojban.: banli lalxu
magyar: Nagy-tavak
македонски: Големи Езера
მარგალური: დიდი ტობეფი
Bahasa Melayu: Tasik-Tasik Besar
Mirandés: Grandes Lagos
монгол: Их нуурууд
မြန်မာဘာသာ: ဂရိတ်လိတ်
Nederlands: Grote Meren
नेपाल भाषा: ग्रेत लेक्स
日本語: 五大湖
norsk nynorsk: Dei store sjøane
oʻzbekcha/ўзбекча: Buyuk koʻllar
ਪੰਜਾਬੀ: ਮਹਾਨ ਝੀਲਾਂ
Piemontèis: Ij Grand Lagh
Plattdüütsch: Grote Seen
русиньскый: Великы озера
саха тыла: Улуу күөллэр
Simple English: Great Lakes
slovenščina: Velika jezera
српски / srpski: Велика језера
srpskohrvatski / српскохрватски: Velika jezera
Türkçe: Büyük Göller
Türkmençe: Beýik köller
українська: Великі озера
vepsän kel’: Sured järved
Tiếng Việt: Ngũ Đại Hồ
吴语: 五大湖
粵語: 五大湖
žemaitėška: Dėdlė̄jė ežerā
中文: 五大湖