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124-697: Originally a footpath for travelers from inland lakes to Lake Superior , the trail was eventually widened into a roadway, and designated as County Road 12 (CR 12). It now serves as a route to lodges, outfitters, hiking trails and the lakes and rivers of the BWCA. A small number of people, numbering in the hundreds, have full-time residences or businesses along the road, though thousands have cabins or other part-time residential properties. The route begins at Highway 61 in Grand Marais. It travels generally northward until Northern Light Lake, where it turns northwestward, following

248-573: A center for logging and commercial fishing . The town today is home to artists and artisans, and tourists who visit for the Gunflint Trail's canoe routes, hiking , fishing and 120 miles (193 km) of trails for cross-country skiing . Grouse , white-tailed deer , black bear , moose , fox , snowshoe hares , wolves , lynx and pine marten inhabit the surrounding forest which comprises spruces , fir , pines , birch and aspen . Lake trout , walleye , northern pike , and bass inhabit

372-504: A coastline is impossible to measure exactly . Canada borders approximately 5,200 miles (8,400 km) of coastline, while the remaining 5,300 miles (8,500 km) are bordered by the United States. Michigan has the longest shoreline of the United States, bordering roughly 3,288 miles (5,292 km) of lakes, followed by Wisconsin (820 miles (1,320 km)), New York (473 miles (761 km)), and Ohio (312 miles (502 km)). Traversing

496-523: A large watershed via many rivers and contain approximately 35,000 islands. There are also several thousand smaller lakes, often called "inland lakes", within the basin. 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. Lake Michigan

620-405: A national basis. The total surface area of the lakes is approximately 94,250 square miles (244,100 km )—nearly the same size as the United Kingdom, and larger than the U.S. states of New York , New Jersey , Connecticut , Rhode Island , Massachusetts , Vermont , and New Hampshire combined. The Great Lakes coast measures approximately 10,500 miles (16,900 km), but the length of

744-456: A nuisance to industries by clogging pipes. The U.S. Fish and Wildlife Service estimated in 2007 that the economic impact of the zebra mussel could be about $ 5 billion over the next decade. The alewife first entered the system west of Lake Ontario via 19th-century canals. By the 1960s, the small silver fish had become a familiar nuisance to beach goers across Lakes Michigan, Huron, and Erie. Periodic mass die-offs result in vast numbers of

868-681: A possible reason for a decrease in population of various whitefish , important because of their culinary desirability and, hence, economic consequence. Moreover, between 1879 and 1899, reported whitefish harvests declined from some 24.3 million pounds (11 million kg) to just over 9 million pounds (4 million kg). By 1900, commercial fishermen on Lake Michigan were hauling in an average of 41 million pounds of fish annually. By 1938, Wisconsin's commercial fishing operations were motorized and mechanized, generating jobs for more than 2,000 workers, and hauling 14 million pounds per year. The population of giant freshwater mussels

992-560: A relatively small area of southeast Lake Michigan where savanna or prairie occasionally intruded). Logging, urbanization, and agriculture uses have changed that relationship. In the early 21st century, Lake Superior's shores are 91% forested, Lake Huron 68%, Lake Ontario 49%, Lake Michigan 41%, and Lake Erie, where logging and urbanization has been most extensive, 21%. Some of these forests are second or third growth (i.e. they have been logged before, changing their composition). At least 13 wildlife species are documented as becoming extinct since

1116-483: A season, and can survive poor water quality conditions. The influx of parasitic lamprey populations after the development of the Erie Canal and the much later Welland Canal led to the two federal governments of the United States and Canada working on joint proposals to control it. By the mid-1950s, the lake trout populations of Lakes Michigan and Huron were reduced, with the lamprey deemed largely to blame. This led to

1240-707: A second fault line, the Saint Lawrence rift , formed approximately 570 million years ago, the basis for Lakes Ontario and Erie was created, along with what would become the Saint Lawrence River. The Great Lakes are estimated to have been formed at the end of the Last Glacial Period (the Wisconsin glaciation ended 10,000 to 12,000 years ago), when the Laurentide Ice Sheet receded. The retreat of

1364-680: A single body of water, as they are joined by Straits of Mackinac .) The Great Lakes Waterway enables modern travel and shipping by water among the lakes. The lakes connect to the Atlantic Ocean via the Saint Lawrence River , and to the Mississippi River basin through the Illinois Waterway . The Great Lakes are the largest group of freshwater lakes on Earth by total area and the second-largest by total volume. They contain 21% of

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1488-673: A small percid fish from Eurasia, became the most abundant fish species in Lake Superior's Saint Louis River within five years of its detection in 1986. Its range, which has expanded to Lake Huron, poses a significant threat to the lower lake fishery. Five years after first being observed in the St. Clair River, the round goby can now be found in all of the Great Lakes. The goby is considered undesirable for several reasons: it preys upon bottom-feeding fish, overruns optimal habitat, spawns multiple times

1612-463: A sunken body will bloat it with gas, causing it to float to the surface after a few days. But Lake Superior's water is cold enough year-round to inhibit bacterial growth , and bodies tend to sink and never resurface. Joe MacInnis reported that in July 1994, explorer Frederick Shannon's Expedition 94 to the wreck of Edmund Fitzgerald discovered a man's body near the port side of her pilothouse, not far from

1736-475: A very small ratio (1.55) of catchment area to surface area, which indicates minimal terrestrial influence. American limnologist J. Val Klump was the first person to reach the lowest depth of Lake Superior on July 30, 1985, as part of a scientific expedition, which at 122 fathoms 1 foot (733 ft or 223 m) below sea level is the second-lowest spot in the continental interior of the United States and

1860-686: Is Isle Royale in Michigan. Isle Royale contains several lakes, some of which also contain islands. Other well-known islands include Madeline Island in Wisconsin, Michipicoten Island in Ontario, and Grand Island (the location of the Grand Island National Recreation Area ) in Michigan. The larger cities on Lake Superior include the twin ports of Duluth, Minnesota , and Superior, Wisconsin ; Thunder Bay , Ontario; Marquette, Michigan ; and

1984-414: Is "new" water, originating from rivers, precipitation, and groundwater springs. In the post-glacial period, evaporation , and drainage have generally been balanced, making the levels of the lakes relatively constant. Intensive human population growth began in the region in the 20th century and continues today. At least two human water use activities have been identified as having the potential to affect

2108-408: Is 0.33 feet (0.10 m) below the datum. In the winter of 1926 Lake Superior reached its lowest recorded level at 1.58 feet (0.48 m) below the datum. Additionally, the entire first half of the year (January to June) included record low months. The low water was a continuation of the dropping lake levels from the previous year, 1925, which set low-water records for October through December. During

2232-423: Is 4,229 feet (1,289 m) above sea level.) While the temperature of the surface of Lake Superior varies seasonally, the temperature below 110 fathoms (660 ft; 200 m) is an almost constant 39 °F (4 °C). This variation in temperature makes the lake seasonally stratified . Twice per year, however, the water column reaches a uniform temperature of 39 °F (4 °C) from top to bottom, and

2356-437: Is 80.5 fathoms (483 ft; 147 m) with a maximum depth of 222.17 fathoms (1,333 ft; 406 m). Lake Superior contains 2,900 cubic miles (12,100 km ) of water. There is enough water in Lake Superior to cover the entire land mass of North and South America to a depth of 30 centimetres (12 in). The shoreline of the lake stretches 2,726 miles (4,387 km) (including islands). The lake boasts

2480-429: Is a designated scenic road system connecting all of the Great Lakes and the St. Lawrence River. Lake Superior's size reduces the severity of the seasons of its humid continental climate (more typically seen in locations like Nova Scotia ). The water surface's slow reaction to temperature changes, seasonally ranging between 32 and 55 °F (0–13 °C) around 1970, helps to moderate surrounding air temperatures in

2604-449: Is an unusual record of environmental nitrogen buildup. It may relate to anthropogenic alternations to the regional nitrogen cycle , but researchers are still unsure of the causes of this change to the lake's ecology. As for other Great Lakes fish, populations have also been affected by the accidental or intentional introduction of foreign species such as the sea lamprey and Eurasian ruffe . Accidental introductions have occurred in part by

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2728-621: Is flat according to the International Joint Commission. Reports about this issue on the U.S. side highlight five large municipal systems (those of Detroit, Cleveland, Buffalo, Milwaukee and Gary ) as being the largest current periodic sources of untreated discharges into the Great Lakes. The fish of the Great Lakes have anti-depressant drugs meant for humans in their brains, which has caused concerns. The number of American adults who take anti-depressant drugs rose from 7.7% of all American adults in 1999–2002 to 12.7% in 2011–2014. As

2852-546: Is heavy. Pleasure boats can 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 ). The lakes were originally fed by both precipitation and meltwater from glaciers which are no longer present. In modern times, only about 1% of volume per year

2976-510: Is the only one of the Great Lakes that is 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 the province of Ontario and the state of Michigan include in their boundaries portions of four of

3100-565: The Brule River . It crosses the Brule and continues north-northwest along Swamper Creek, gradually arcing westward and running along the northern shore of Poplar Lake. The road continues west past several lakes including Birch, Mayhew , and Loon before reaching the access roads to Gunflint Lake . The route turns north near Round Lake and travels several miles to Sea Gull Lake , where it turns west again to its terminus at Saganaga Lake . The footpath

3224-944: The Chicago Sanitary and Ship Canal to the Gulf of Mexico via 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

3348-731: The Door Peninsula , the Peninsulas of Michigan , and the Ontario Peninsula . Some of these peninsulas even contain smaller peninsulas, such as the Bruce , Keweenaw , Leelanau , Niagara , and Thumb peninsulas. Population centers on the peninsulas include Grand Rapids , Flint , and Detroit in Michigan along with London , Hamilton , Brantford , and Toronto in Ontario. Although the Saint Lawrence Seaway and Great Lakes Waterway make

3472-516: The Environmental Protection Agency have shown that when the mercury comes in contact with many of the bacteria and compounds in the fresh water, it forms the compound methyl mercury , which has a much greater impact on human health than elemental mercury due to a higher propensity for absorption. This form of mercury is not detrimental to a majority of fish types, but is very detrimental to people and other wildlife animals who consume

3596-669: The Finger Lakes region of New York, as well as in Prince Edward County, Ontario , on Lake Ontario's northeast shore. The Great Lakes have been observed to help intensify storms, such as Hurricane Hazel in 1954, and the 2011 Goderich, Ontario tornado , which moved onshore as a tornadic waterspout . In 1996, a rare tropical or subtropical storm was observed forming in Lake Huron, dubbed the 1996 Lake Huron cyclone . Rather large severe thunderstorms covering wide areas are well known in

3720-671: The Hudson Bay watershed, are regulated by the International Lake Superior Board of Control , which was established in 1914 by the International Joint Commission . Lake Superior's water level was at a new record low in September 2007, slightly less than the previous record low in 1926. Water levels recovered within a few days. Historic high water The lake's water level fluctuates from month to month, with

3844-513: The Niagara Escarpment precludes all natural navigation, the four upper lakes are commonly called the "upper great lakes". This designation 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

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3968-732: The Pic River , the White River , the Michipicoten River , the Bois Brule River and the Kaministiquia River . The lake's outlet at St. Marys River has a relatively steep gradient with rapids. The Soo Locks enable ships to bypass the rapids and to overcome the 25-foot (8 m) height difference between Lakes Superior and Huron. The lake's average surface elevation is 600 feet (183 m) above sea level . Until approximately 1887,

4092-739: The Whitefish Point Underwater Preserve . Storms that claimed multiple ships include the Mataafa Storm in November 1905 and the Great Lakes Storm of 1913 . Wreckage of SS  Cyprus —a 420-foot (130 m) ore carrier that sank on October 11, 1907, during a Lake Superior storm in 77 fathoms (460 ft or 140 m) of water—was located in August 2007. Built in Lorain, Ohio , Cyprus

4216-497: The biosphere . Since the 19th century, an estimated 160 new species have found their way into the Great Lakes ecosystem; many have become invasive; the overseas ship ballast and ship hull parasitism are causing severe economic and ecological impacts. According to the Inland Seas Education Association, on average a new species enters the Great Lakes every eight months. Introductions into the Great Lakes include

4340-495: The lake effect snow belts along the shores of the lake, especially in the Upper Peninsula of Michigan . Two recent consecutive winters (2013–2014 and 2014–2015) brought high ice coverage to the Great Lakes, and on March 6, 2014, overall ice coverage peaked at 92.5%, the second-highest in recorded history. Lake Superior's ice coverage further beat 2014's record in 2019, reaching 95% coverage. The largest island in Lake Superior

4464-414: The zebra mussel , which was first discovered in 1988, and quagga mussel in 1989. Since 2000, the invasive quagga mussel has smothered the bottom of Lake Michigan almost from shore to shore, and their numbers are estimated at 900 trillion. The mollusks are efficient filter feeders, competing with native mussels and reducing available food and spawning grounds for fish. In addition, the mussels may be

4588-527: The " snowbelts " receive regular snow fall from this localized weather pattern, especially along the eastern shores of the lakes. Snowbelts are found in Wisconsin, Michigan, Ohio, Pennsylvania, New York, and Ontario. Related to the lake effect is the regular occurrence of fog, particularly along the shorelines of the lakes. This is most noticeable along Lake Superior's shores. The lakes tend to moderate seasonal temperatures to some degree but not with as large an influence as do large oceans; they absorb heat and cool

4712-630: The Canadian province of Ontario to the north and east and the U.S. states of Minnesota to the west and Michigan and Wisconsin to the south. It drains into Lake Huron via St. Marys River , then through the lower Great Lakes to the St. Lawrence River and ultimately the Atlantic Ocean. The Ojibwe name for the lake is gichi-gami (in syllabics : ᑭᒋᑲᒥ , pronounced gitchi-gami or kitchi-gami in different dialects), meaning "great sea". Henry Wadsworth Longfellow wrote this name as " Gitche Gumee " in

4836-560: The Canadian side, Toronto , Hamilton and Mississauga . Though the five lakes lie in separate basins, they form a single, naturally interconnected body of fresh water, within the Great Lakes Basin . As a chain of lakes and rivers, they connect 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

4960-489: The Chicago Sanitary and Ship Canal in order to keep several species of invasive Asian carp out of the lakes. These fast-growing planktivorous fish have heavily colonized the Mississippi and Illinois river systems. Invasive species, particularly zebra and quagga mussels, may be at least partially responsible for the collapse of the deepwater demersal fish community in Lake Huron, as well as drastic unprecedented changes in

5084-458: The Great Lakes accessible to ocean-going vessels, 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. Larger ships are confined to working within

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5208-459: The Great Lakes during mid-summer; these Mesoscale convective complexes or MCCs can cause damage to wide swaths of forest and shatter glass in city buildings. These storms mainly occur during the night, and the systems sometimes have small embedded tornadoes, but more often straight-line winds accompanied by intense lightning. Historically, the Great Lakes, in addition to their lake ecology , were surrounded by various forest ecoregions (except in

5332-441: The Great Lakes each year. Plastics in the water break up into very small particles known as microplastics . Microplastics can also come from synthetic clothing washed down our drains. Plastic waste found in the lakes include single-use plastics , plastics used in packaging, takeout containers as well as pre-production pellets produced by plastics industry . High concentrations of microplastics were discovered in 100 percent of

5456-438: The Great Lakes region include: Plant lists include: Logging of the extensive forests in the Great Lakes region removed riparian and adjacent tree cover over rivers and streams, which provide shade, moderating water temperatures in fish spawning grounds. Removal of trees also destabilized the soil, with greater volumes washed into stream beds causing siltation of gravel beds, and more frequent flooding. Running cut logs down

5580-550: The Great Lakes. A number of self-operating floating devices called Seabin, were put in the Great Lakes to capture plastic trash as part of the Great Lakes Plastic Cleanup project. The project captured 74,000 pieces of trash using this technology between 2020 and 2021; however, it does not claim to catch up with 22 million pounds (10.0 kt) of plastic that ends up in Great Lakes every year. The production, consumption, and throwing away of plastics seems to remain

5704-513: The Hudson's Bay Company name. Many towns around the lake are current or former mining areas, or engaged in processing or shipping. Today, tourism is another significant industry: the sparsely populated Lake Superior country, with its rugged shorelines and wilderness, attracts vacationers and adventurers. Lake Superior has been an important link in the Great Lakes Waterway , providing a route for

5828-542: The Midcontinent Rift, and there are several amethyst mines in the Thunder Bay area. Lava erupted from the rift and formed the black basalt rock of Michipicoten Island, Black Bay Peninsula, and St. Ignace Island . In the most recent geological history, during the Wisconsin glaciation 10,000 years ago, ice covered the region at a thickness of 1.25 miles (2 km). The land contours familiar today were carved by

5952-548: The Ojibwe name as Otchipwe-kitchi-gami (a transliteration of Ojibwe Gichigami ). In the 17th century, the first French explorers approached the great inland sea by way of the Ottawa River and Lake Huron; they referred to their discovery as le lac supérieur (the upper lake, i.e., above Lake Huron). Some 17th-century Jesuit missionaries referred to it as Lac Tracy (for Alexandre de Prouville de Tracy ). After taking control of

6076-500: The Straits of Mackinac. The straits are five miles (8 km) wide and 120 feet (37 m) deep; the water levels rise and fall together, and the flow between Michigan and Huron frequently reverses direction. Dispersed throughout the Great Lakes are approximately 35,000 islands . The largest among them is Manitoulin Island in Lake Huron, the largest island in any inland body of water in

6200-427: The U.S. A variety of steps taken to process industrial and municipal pollution discharges into the system greatly improved water quality by the 1980s, and Lake Erie in particular is significantly cleaner. Discharge of toxic substances has been sharply reduced. Federal and state regulations control substances like PCBs . The first of 43 " Great Lakes Areas of Concern " to be formally "de-listed" through successful cleanup

6324-554: The Upper Gunflint Trail, burning over 40,000 acres (160 km) in the Boundary Waters Canoe Area and Ontario's Quetico Provincial Park. The fire lasted several weeks and claimed almost 200 structures, although no one was seriously injured or killed. It was started accidentally by an unattended campfire at a campsite on Ham Lake. The fire drew national attention and a visit from Governor Tim Pawlenty , who inspected

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6448-478: The advance and retreat of the ice sheet . The retreat left gravel, sand, clay and boulder deposits. Glacial meltwaters gathered in the Superior basin creating Lake Minong , a precursor to Lake Superior. Without the immense weight of the ice, the land rebounded , and a drainage outlet formed at Sault Ste. Marie, becoming today's St. Mary's River. The first people came to the Lake Superior region 10,000 years ago after

6572-495: The air in summer, then slowly radiate that heat in autumn. They protect against frost during transitional weather and keep the summertime temperatures cooler than further inland. This effect can be very localized and overridden by offshore wind patterns. This temperature buffering produces areas known as " fruit belts ", where fruit can be produced that is typically grown much farther south. For instance, western Michigan has apple orchards, and cherry orchards are cultivated adjacent to

6696-459: The anti-depressant drugs pass out of human bodies and through sanitation systems into the Great Lakes, this has resulted in fish in the Great Lakes with twenty times the level of anti-depressants in their brains than what is in the water, leading to the fish being exceedingly happy and hence less risk-averse, to the extent of damaging the fish populations. Researchers have found that more than 22 million pounds (10.0 kt) of plastic end up in

6820-412: The area's geographical features, forming basins running east to west with the region's bedrock, and when they retreated, lakes formed. The Ojibwa and French explorers found chert , which produces sparks, at Gunflint Lake and gave the trail its name. In contemporary times, both fire and wind put stress on the area. The Ojibwa built a village that is now Grand Marais, which became a trading post and

6944-432: The arrival of Europeans, and many more are threatened or endangered. Meanwhile, exotic and invasive species have also been introduced. While the organisms living on the bottom of shallow waters are similar to those found in smaller lakes, the deep waters contain organisms found only in deep, cold lakes of the northern latitudes. These include the delicate opossum shrimp (order mysida ), the deepwater scud (a crustacean of

7068-609: The arrival of Europeans, the Anishinaabe made themselves middle-men between the French fur traders and other Native peoples. They soon became the dominant Native American nation in the region: they forced out the Sioux and Fox and won a victory against the Iroquois west of Sault Ste. Marie in 1662. By the mid-18th century, the Ojibwe occupied all of Lake Superior's shores. In the 18th century, as

7192-673: The basins they had carved into the land, which then filled with meltwater. The lakes have been a major source for transportation, migration, trade, and fishing, serving as a habitat to many aquatic species in a region with much biodiversity . The surrounding region is called the Great Lakes region , which includes the Great Lakes Megalopolis . Major cities within the region include, on the American side, from east to west, Buffalo , Cleveland , Detroit , Chicago , and Milwaukee ; and, on

7316-586: The booming fur trade supplied Europe with beaver hats , the Hudson's Bay Company had a virtual monopoly in the region until 1783, when the rival North West Company was formed. The North West Company built forts on Lake Superior at Grand Portage , Fort William , Nipigon, the Pic River, the Michipicoten River, and Sault Ste. Marie. But by 1821, with competition harming the profits of both, the companies merged under

7440-427: The core of Great Lakes trash problem. Algae such as diatoms , along with other phytoplankton , are photosynthetic primary producers supporting the food web of the Great Lakes, and have been affected by global warming . The changes in the size or in the function of the primary producers may have a direct or an indirect impact on the food web. Photosynthesis carried out by diatoms constitutes about one fifth of

7564-701: The cyanobacteria ... will produce toxins", said Michael McKay, of the University of Windsor. Water quality testing was underway in August 2019. Until 1970, mercury was not listed as a harmful chemical, according to the United States Federal Water Quality Administration. In the 21st century, mercury has become more apparent in water tests. Mercury compounds have been used in paper mills to prevent slime from forming during their production, and chemical companies have used mercury to separate chlorine from brine solutions. Studies conducted by

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7688-522: The damage first-hand. Despite the significant damage to the forest, most outfitters and commercial businesses have reopened and access to the region's lakes has resumed. Located along a portion of the "Old Gunflint Trail", the post office was originally located in the Voyagers Inn and run by its first postmaster George Stapleton. It was later purchased by Lawrence F. Wooding (Gus) in the early 1950s and came to be known as "Woody's Place". Glaciers created

7812-608: The direct ancestors of the Ojibwe and Cree . The people of the Laurel complex (c. 500 BC to AD 500) developed seine net fishing, evidence being found at rivers around Superior such as the Pic and Michipicoten. The people of the Terminal Woodland period were evident in the area from AD 900 to 1650. They were Algonquian peoples who hunted, fished and gathered berries. They used snowshoes , birch bark canoes and conical or domed lodges. At

7936-401: The fish that were studied by researchers from the Rochman Lab. About 50 million pounds (23 kt) of fish is harvested each year from Great Lakes which has raised concerns on how this might affect human health. Microscopic pieces of plastic have also been found in drinking water coming from Great Lakes. It is estimated that nearly 40 million people in the region rely on drinking water from

8060-443: The fish washing up on shore; estimates by various governments have placed the percentage of Lake Michigan's biomass which was made up of alewives in the early 1960s as high as 90%. In the late 1960s, the various state and federal governments began stocking several species of salmonids, including the native lake trout as well as non-native chinook and coho salmon; by the 1980s, alewife populations had dropped drastically. The ruffe ,

8184-443: The fish. Mercury has been known for health related problems such as birth defects in humans and animals, and the near extinction of eagles in the Great Lakes region. The amount of raw sewage dumped into the waters was the primary focus of both the first Great Lakes Water Quality Agreement and federal laws passed in both countries during the 1970s. Implementation of secondary treatment of municipal sewage by major cities greatly reduced

8308-471: The five Great Lakes have long been called inland seas . Depending on how it is measured, by surface area, either Lake Superior or Lake Michigan–Huron is the second-largest lake in the world and the largest freshwater lake. Lake Michigan is the largest lake, by surface area, that is entirely within one country, the United States. The Great Lakes began to form at the end of the Last Glacial Period around 14,000 years ago, as retreating ice sheets exposed

8432-417: The glaciers "rebounded" as it was uncovered. Since the glaciers covered some areas longer than others, this glacial rebound occurred at different rates. The Great Lakes have a humid continental climate, Köppen climate classification Dfa (in southern areas) and Dfb (in northern parts) with varying influences from air masses from other regions including dry, cold Arctic systems, mild Pacific air masses from

8556-428: The highest lake levels in October and November. The normal high-water mark is 1.17 feet (0.36 m) above the datum (601.1 ft or 183.2 m). In the summer of 1985, Lake Superior reached its highest recorded level at 2.33 feet (0.71 m) above the datum. 2019 and 2020 set new high-water records in nearly every month. Historic low water The lake's lowest levels occur in March and April. The normal low-water mark

8680-410: The historical average level. Although "true tides—changes in water level caused by the gravitational forces of the sun and moon—do occur in a semi-diurnal (twice daily) pattern", such changes are quite small and generally obscured by other forces. The lake levels are affected primarily by changes in regional meteorology and climatology. The outflows from Lakes Superior and Ontario are regulated, while

8804-442: The ice sheet left behind a large amount of meltwater ( Lake Algonquin , Lake Chicago , Glacial Lake Iroquois , and Champlain Sea ) that filled up the basins that the glaciers had carved, thus creating the Great Lakes as they are today. 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. Land below

8928-545: The key indicators even in the current 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 (66,000 long tons; 74,000 short tons) [147 million pounds]." By 1801, the New York Legislature found it necessary to pass regulations curtailing obstructions to

9052-597: The lake and causing blooms," said Michael McKay, executive director of the Great Lakes Institute for Environmental Research (GLIER) at the University of Windsor . The largest Lake Erie bloom to date occurred in 2015, exceeding the severity index at 10.5 and in 2011 at a 10. In early August 2019, satellite images depicted a bloom stretching up to 1,300 square kilometres on Lake Erie, with the heaviest concentration near Toledo, Ohio . A large bloom does not necessarily mean

9176-621: The lake appeared to have increased by about 4.5 °F (2.5 °C) between 1979 and 2007, compared with an approximately 2.7 °F (1.5 °C) increase in the surrounding average air temperature. The increase in the lake's surface temperature may be related to the decreasing ice cover. Less winter ice cover allows more solar radiation to penetrate and warm the water. If trends continue, Lake Superior, which freezes over completely once every 20 years, could routinely be ice-free by 2040 although more current data through 2021 does not support this trend. Warmer temperatures could lead to more snow in

9300-634: The lake shore as far north as the Grand Traverse Bay . Near Collingwood, Ontario , commercial fruit orchards, including a few wineries, exist near the shoreline of southern Nottawasaga Bay . The eastern shore of Lake Michigan and the southern shore of Lake Erie have many successful wineries because of the lakes' moderating effects, as do the large commercial fruit and wine growing areas of the Niagara Peninsula located between Lake Erie and Lake Ontario. A similar phenomenon allows wineries to flourish in

9424-527: The lake waters thoroughly mix. This feature makes the lake dimictic . Because of its volume, Lake Superior has a retention time of 191 years. Annual storms on Lake Superior regularly feature wave heights of over 20 feet (6 m). Waves well over 30 feet (9 m) have been recorded. Lake Superior is fed by more than 200 rivers, including the Nipigon River , the St. Louis River , the Pigeon River ,

9548-522: The lake. With 78 crewmembers dead, their sinking marked the largest loss of life on Lake Superior to date. SS  Edmund Fitzgerald is the last ship that sank in Lake Superior, 15 nautical miles (28 km; 17 mi) from Whitefish Point in a storm on November 10, 1975. The wreck was immortalized by Gordon Lightfoot in his ballad "The Wreck of the Edmund Fitzgerald " . All 29 crew members died, and no bodies were recovered. Edmund Fitzgerald

9672-525: The lakes has been observed since records began in 1918. The water level of Lake Michigan–Huron had remained fairly constant over the 20th century. Recent lake levels include record low levels in 2013 in Lakes Superior, Erie, and Michigan-Huron, followed by record high levels in 2020 in the same lakes. The water level in Lake Ontario has remained relatively constant in the same time period, hovering around

9796-464: 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). Outflows through the Chicago Sanitary and Ship Canal is more than balanced by artificial inflows via the Ogoki River and Long Lake/ Kenogami River diversions. Fluctuation of the water levels in

9920-454: The lakes. 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 connected by

10044-415: The lakes. The province of Ontario does not border Lake Michigan, and the state of 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. 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

10168-468: 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. Lakes Huron and Michigan are sometimes considered a single lake, called Lake Michigan–Huron, because they are one hydrological body of water connected by

10292-494: The launch of the bi-national Great Lakes Fishery Commission . Several species of exotic water fleas have accidentally been introduced into the Great Lakes, such as the spiny waterflea, Bythotrephes longimanus , and the fishhook waterflea, Cercopagis pengoi , potentially having an effect on the zooplankton population. Several species of crayfish have also been introduced that may contend with native crayfish populations. More recently an electric fence has been set up across

10416-472: The many lakes along the Gunflint Trail. Lake Superior Lake Superior is the largest freshwater lake in the world by surface area and the third-largest freshwater lake by volume , holding 10% of the world's surface fresh water. Located in central North America, it is the northernmost and westernmost of the Great Lakes of North America , straddling the Canada–United States border with

10540-674: The most frequently mined. Notable production includes gold from the Hemlo mine near Marathon , copper from the Keweenaw Peninsula and the Mamainse Point Formation , iron from the Gogebic Range , silver at Silver Islet , and uranium at Theano Point. The mountains steadily eroded, depositing layers of sediments that compacted and became limestone , dolomite , taconite and the shale at Kakabeka Falls . The continental crust

10664-567: The mouth of the Michipicoten River, nine layers of encampments have been discovered. Most of the Pukaskwa Pits were likely made during this time. The Anishinaabe people (an ethnic grouping including the Ojibwe/Chippewa ) have inhabited the Lake Superior region for over five hundred years and were preceded by the Dakota , Meskwaki (Fox) , Menominee , Nipigon, Noquet and Gros Ventres . After

10788-529: The natural hydraulic conveyance through the St. Marys River rapids determined the outflow from Lake Superior. By 1921, development in support of transportation and hydroelectric power resulted in gates, locks, power canals and other control structures completely spanning St. Marys rapids. The regulating structure is known as the Compensating Works and is operated according to a regulation plan known as Plan 1977-A. Water levels, including diversions of water from

10912-476: The natural migrations of Atlantic salmon from Lake Erie into their spawning channels. In the early 19th century, the government of Upper Canada found it necessary to introduce similar legislation prohibiting the use of weirs and nets at the mouths of Lake Ontario's tributaries. Other protective legislation was passed, but enforcement remained difficult. On both sides of the Canada–United States border,

11036-453: The nine-month period of October 1925 to June 1926, water levels ranged from 1.58 feet (0.48 m) to 0.33 feet (0.10 m) below Chart Datum. In the summer of 2007 monthly historic lows were set; August at 0.66 feet (0.20 m), and September at 0.58 feet (0.18 m). According to a study by professors at the University of Minnesota Duluth , Lake Superior may have warmed faster than its surrounding area. Summer surface temperatures in

11160-1027: The open door, "fully clothed, wearing an orange life jacket, and lying face down in the sediment". In February 2024 it was announced that wreckage from the Arlington was discovered from a sinking in 1940. More than 80 species of fish have been found in Lake Superior. Species native to the lake include banded killifish , bloater , brook trout , burbot , cisco , lake sturgeon , lake trout , lake whitefish , longnose sucker , muskellunge , northern pike , pumpkinseed , rock bass , round whitefish , smallmouth bass , walleye , white sucker and yellow perch . In addition, many fish species have been either intentionally or accidentally introduced to Lake Superior: Atlantic salmon , brown trout , carp , chinook salmon , coho salmon , freshwater drum , pink salmon , rainbow smelt , rainbow trout , round goby , ruffe , sea lamprey and white perch . Lake Superior has fewer dissolved nutrients relative to its water volume than

11284-463: The order amphipoda ), two types of copepods , and the deepwater sculpin (a spiny, large-headed fish). The Great Lakes are an important source of fishing . Early European settlers were astounded by both the variety and quantity of fish; there were 150 different species in the Great Lakes. Throughout history, fish populations were the early indicator of the condition of the Lakes and have remained one of

11408-514: The other Great Lakes and so is less productive in terms of fish populations and is an oligotrophic lake . This is a result of the underdeveloped soils found in its relatively small watershed. It is also a reflection of relatively small human population and small amount of agriculture in its watershed. However, nitrate concentrations in the lake have been continuously rising for more than a century. They are still much lower than levels considered dangerous to human health; but this steady, long-term rise

11532-558: The other Great Lakes began sailing in 1816. Ice closes the lake shipping from mid-January to late March. Exact dates for the shipping season vary each year, depending on weather conditions that form and break the ice. The southern shore of Lake Superior between Grand Marais, Michigan , and Whitefish Point is known as the " Graveyard of the Great Lakes "; more ships have been lost around the Whitefish Point area than any other part of Lake Superior. These shipwrecks are now protected by

11656-506: The outflows of Michigan-Huron and Erie are not regulated at all. Ontario is the most tightly regulated, with its outflow controlled by the Moses-Saunders Power Dam , which explains its consistent historical levels. The Great Lakes contain 21% of the world's surface fresh water: 5,472 cubic miles (22,810 km ), or 6.0×10 U.S. gallons, that is 6 quadrillion U.S. gallons, (2.3×10 liters). The lakes contain about 84% of

11780-451: The poem The Song of Hiawatha , as did Gordon Lightfoot in his song " The Wreck of the Edmund Fitzgerald ". According to other sources, the full Ojibwe name is ᐅᒋᑉᐧᐁ ᑭᒋᑲᒥ Ojibwe Gichigami ("Ojibwe's Great Sea") or ᐊᓂᐦᔑᓈᐯ ᑭᒋᑲᒥ Anishinaabe Gichigami (" Anishinaabe 's Great Sea"). The 1878 dictionary by Father Frederic Baraga , the first one written for the Ojibway language, gives

11904-507: The proliferation of dams and impoundments have multiplied, necessitating more regulatory efforts. Concerns by the mid-19th century included obstructions in the rivers which prevented salmon and lake sturgeon from reaching their spawning grounds. The Wisconsin Fisheries Commission noted a reduction of roughly 25% in general fish harvests by 1875. The states have removed dams from rivers where necessary. Overfishing has been cited as

12028-550: The region from the French in the 1760s following their defeat in the French and Indian War , the British anglicized the lake's name to Superior , "on account of its being superior in magnitude to any of the lakes on that vast continent". Lake Superior empties into Lake Huron via the St. Marys River and the Soo Locks (Sault Ste. Marie locks). Lake Superior is the largest freshwater lake in

12152-499: The removal of natural barriers to navigation between the Great Lakes. Overfishing has also been a factor in the decline of fish populations. Great Lakes of North America The Great Lakes ( French : Grands Lacs ), also called the Great Lakes of North America , are a series of large interconnected freshwater lakes spanning the Canada–United States border . The five lakes are Superior , Michigan , Huron , Erie , and Ontario . (Hydrologically, Michigan and Huron are

12276-536: The retreat of the glaciers in the Last Glacial Period . They are known as the Plano , and they used stone-tipped spears to hunt caribou on the northwestern side of Lake Minong. The Shield Archaic peoples arrived around 5000 BC; evidence of this culture can be found at the eastern and western ends of the Canadian shore. They used bows and arrows, paddled dugout canoes, fished, hunted, mined copper for tools and weapons, and established trading networks. They are believed to be

12400-428: The routine discharge of untreated sewage during the 1970s and 1980s. The International Joint Commission in 2009 summarized the change: "Since the early 1970s, the level of treatment to reduce pollution from waste water discharges to the Great Lakes has improved considerably. This is a result of significant expenditures to date on both infrastructure and technology, and robust regulatory systems that have proven to be, on

12524-436: The shoreline of all the lakes would cover a distance roughly equivalent to travelling half-way around the world at the equator. A notable modern phenomenon is the formation of ice volcanoes over the lakes during wintertime. Storm-generated waves carve the lakes' ice sheet and create conical mounds through the eruption of water and slush. The process is only well-documented in the Great Lakes, and has been credited with sparing

12648-583: The southern shorelines from worse rocky erosion. It has been estimated that the foundational geology that created the conditions shaping the present day upper Great Lakes was laid from 1.1 to 1.2 billion years ago, when two previously fused tectonic plates split apart and created the Midcontinent Rift , which crossed the Great Lakes Tectonic Zone . A valley was formed providing a basin that eventually became modern day Lake Superior. When

12772-466: The summer (cooler with frequent sea breeze formations) and winter, and creates lake-effect snow in colder months. The hills and mountains that border the lake hold moisture and fog, particularly in the fall. The rocks of Lake Superior's northern shore date back to the early history of the earth. During the Precambrian (between 4.5 billion and 540 million years ago) magma forcing its way to

12896-559: The surface created the intrusive granites of the Canadian Shield . These ancient granites can be seen on the North Shore today. It was during the Penokean orogeny , part of the process that created the Great Lakes tectonic zone , that many valuable metals were deposited. The region surrounding the lake has proved to be rich in minerals, with copper , iron , silver , gold and nickel

13020-414: The surface freshwater of North America; if the water were evenly distributed over the entire continent's land area, it would reach a depth of 5 feet (1.5 meters). This is enough water to cover the 48 contiguous U.S. states to a uniform depth of 9.5 feet (2.9 m). Although the lakes contain a large percentage of the world's fresh water, the Great Lakes supply only a small portion of U.S. drinking water on

13144-570: The third-lowest spot in the interior of the North American continent after Great Slave Lake in the Northwest Territories of Canada (1,503 ft or 458 m below sea level) and Iliamna Lake in Alaska 942 ft or 287 m. (Though Crater Lake is the deepest lake in the United States and deeper than Lake Superior, Crater Lake's elevation is higher and consequently its deepest point

13268-456: The transportation of iron ore as well as grain and other mined and manufactured materials. Large cargo vessels called lake freighters , as well as smaller ocean-going freighters , transport these commodities across Lake Superior. Shipping was slow to arrive at Lake Superior in the 19th century. The first steamboat to run on the lake was the Independence in 1847, whereas the first steamers on

13392-551: The treatment plant, are temporarily overwhelmed by heavy rainstorms. Local sewage treatment authorities then must release untreated effluent, a mix of rainwater and sewage, into local water bodies. While enormous public investments such as the Deep Tunnel projects in Chicago and Milwaukee have greatly reduced the frequency and volume of these events, they have not been eliminated. The number of such overflow events in Ontario, for example,

13516-522: The tributary rivers into the Great Lakes also dislocated sediments. In 1884, the New York Fish Commission determined that the dumping of sawmill waste (chips and sawdust) had impacted fish populations. The first U.S. Clean Water Act , passed by a Congressional override after being vetoed by U.S. President Richard Nixon in 1972, was a key piece of legislation, along with the bi-national Great Lakes Water Quality Agreement signed by Canada and

13640-747: The twin cities of Sault Ste. Marie, Michigan , and Sault Ste. Marie, Ontario . Duluth-Superior , at the western end of Lake Superior, is the most inland point on the Saint Lawrence Seaway and the most inland port in the world. Among the scenic places on the lake are Apostle Islands National Lakeshore , Brockway Mountain Drive on the Keweenaw Peninsula , Isle Royale National Park , Porcupine Mountains Wilderness State Park , Pukaskwa National Park , Lake Superior Provincial Park , Grand Island National Recreation Area, Sleeping Giant (Ontario) and Pictured Rocks National Lakeshore . The Great Lakes Circle Tour

13764-416: The warmer and shallower portions of the system such as Lake Erie, Saginaw Bay , Green Bay , and the southernmost portion of Lake Michigan. By the mid-1980s, most jurisdictions bordering the Great Lakes had controlled phosphate detergents . Blue-green algae, or cyanobacteria blooms, have been problematic on Lake Erie since 2011. "Not enough is being done to stop fertilizer and phosphorus from getting into

13888-430: The west pick up the air and moisture from the lake surface, which is slightly warmer in relation to the cold surface winds above. As the slightly warmer, moist air passes over the colder land surface, the moisture often produces concentrated, heavy snowfall that sets up in bands or "streamers". This is similar to the effect of warmer air dropping snow as it passes over mountain ranges. During freezing weather with high winds,

14012-427: The west, and warm, wet tropical systems from the south and the Gulf of Mexico. The lakes have a moderating effect on the climate; they can also increase precipitation totals and produce lake effect snowfall . The Great Lakes can have an effect on regional weather called lake-effect snow , which is sometimes very localized. Even late in winter, the lakes often have no icepack in the middle. The prevailing winds from

14136-480: The whole, quite effective." The commission reported that all urban sewage treatment systems on the U.S. side of the lakes had implemented secondary treatment, as had all on the Canadian side except for five small systems. Though contrary to federal laws in both countries, those treatment system upgrades have not yet eliminated combined sewer overflow events. This describes when older sewerage systems, which combine storm water with sewage into single sewers heading to

14260-637: The world by area and the third largest in volume, behind Lake Baikal in Siberia and Lake Tanganyika in East Africa . The Caspian Sea , while larger than Lake Superior in both surface area and volume, is brackish . Lake Superior has a surface area of 31,700 square miles (82,103 km ), which is approximately the size of South Carolina or Austria . It has a maximum length of 350 statute miles (560  km ; 300  nmi ) and maximum breadth of 160 statute miles (257 km; 139 nmi). Its average depth

14384-472: The world's surface fresh water by volume. The total surface is 94,250 square miles (244,106 km ), and the total volume (measured at the low water datum) is 5,439 cubic miles (22,671 km ), slightly less than the volume of Lake Baikal (5,666 cu mi or 23,615 km , 22–23% of the world's surface fresh water). Because of their sea-like characteristics, such as rolling waves, sustained winds, strong currents, great depths, and distant horizons,

14508-552: The world. The second-largest island is Isle Royale in Lake Superior. 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 on a freshwater island. Some of these lakes even have their own islands, like Treasure Island in Lake Mindemoya in Manitoulin Island. The Great Lakes also have several peninsulas between them, including

14632-523: The zooplankton community of the lake. Scientists understand that the micro-aquatic life of the lakes is abundant but know very little about some of the most plentiful microbes and their environmental effects in the Great Lakes. Although a drop of lake water may contain 1 million bacteria cells and 10 million viruses , only since 2012 has there been a long-term study of the lakes' micro-organisms. Between 2012 and 2019 more than 160 new species have been discovered. Native habitats and ecoregions in

14756-546: Was Ontario's Collingwood Harbour in 1994; Ontario's Severn Sound followed in 2003. Presque Isle Bay in Pennsylvania is formally listed as in recovery, as is Ontario's Spanish Harbour. Dozens of other Areas of Concern have received partial cleanups such as the Rouge River (Michigan) and Waukegan Harbor (Illinois). Phosphate detergents were historically a major source of nutrient to the Great Lakes algae blooms in particular in

14880-406: Was battered so intensely by Lake Superior that the 729-foot (222 m) ship split in half; her two pieces lie approximately 170 feet (52 m) apart at a depth of 88 fathoms (530 ft or 160 m). Lightfoot sings that "Superior, they said, never gives up her dead". This is because of the unusually cold water, under 36 °F (2 °C) on average around 1970. Normally, bacteria decaying

15004-517: Was eliminated as the mussels were harvested for use as buttons by early Great Lakes entrepreneurs. The Great Lakes: An Environmental Atlas and Resource Book (1972) notes: "Only pockets remain of the once large commercial fishery." Water quality improvements realized during the 1970s and 1980s, combined with successful salmonid stocking programs, have enabled the growth of a large recreational fishery. The last commercial fisherman left Milwaukee in 2011 because of overfishing and anthropogenic changes to

15128-461: Was improved into a dirt road by Cook County in the 1890s to support the Paulson Mine . In the 1920s, local business owners paid for some improvements to the road; by 1957, it was paved from Grand Marais to Hungry Jack Lake . The last gravel section, south of Sea Gull Lake, was paved in 1979. The road was designated a National Scenic Byway in 2009. The Ham Lake Fire of spring 2007 severely impacted

15252-472: Was later riven , creating one of the deepest rifts in the world. The lake lies in this long-extinct Mesoproterozoic rift valley , the Midcontinent Rift . Magma was injected between layers of sedimentary rock , forming diabase sills . This hard diabase protects the layers of sedimentary rock below, forming the flat-topped mesas in the Thunder Bay area. Amethyst formed in some of the cavities created by

15376-486: Was launched August 17, 1907, and was lost on her second voyage hauling iron ore from Superior, Wisconsin, to Buffalo, New York , with the sole survivor among her 23 crew being Charles G. Pitz. In 1918 the last warships to sink in the Great Lakes, French minesweepers Inkerman and Cerisoles , vanished in a Lake Superior storm, perhaps upon striking the uncharted danger of the Superior Shoal in an otherwise deep part of

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