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105-755: The Apalachicola-Chattahoochee-Flint River Basin (the ACF River Basin ) is the drainage basin , or watershed, of the A palachicola River , C hattahoochee River , and F lint River , in the Southeastern United States . This area is alternatively known as simply the Apalachicola Basin and is listed by the United States Geological Survey as basin HUC 031300, as well as sub-region HUC 0313. It

210-498: A closed drainage basin, or endorheic basin , rather than flowing to the ocean, water converges toward the interior of the basin, known as a sink , which may be a permanent lake, a dry lake , or a point where surface water is lost underground . Drainage basins are similar but not identical to hydrologic units , which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system . Hydrologic units are defined to allow multiple inlets, outlets, or sinks. In

315-511: 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

420-444: A drainage basin are catchment area , catchment basin , drainage area , river basin , water basin , and impluvium . In North America, they are commonly called a watershed , though in other English-speaking places, "watershed" is used only in its original sense, that of the drainage divide line. A drainage basin's boundaries are determined by watershed delineation , a common task in environmental engineering and science. In

525-454: A drainage basin, and there are different ways to interpret that data. In the unlikely event that the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results. In the Thiessen polygon method, the drainage basin is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for

630-540: A drainage boundary is referred to as watershed delineation . Finding the area and extent of a drainage basin is an important step in many areas of science and engineering. Most of the water that discharges from the basin outlet originated as precipitation falling on the basin. A portion of the water that enters the groundwater system beneath the drainage basin may flow towards the outlet of another drainage basin because groundwater flow directions do not always match those of their overlying drainage network. Measurement of

735-528: A large enough flow of fresh water to prevent excessive saltwater intrusion from the Gulf. Numerous endangered and imperiled species occur in the basin, including many endemic mussels The cost of dredging silt , much of it caused by uncontrolled growth across metro Atlanta's fine red clay soil, has also been criticized as a wasteful exercise to float so little ship traffic. Drainage basin Other terms for

840-533: 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

945-405: 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

1050-456: 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

1155-681: 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

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1260-560: 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

1365-489: 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

1470-746: 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

1575-712: 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

1680-689: 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

1785-743: A small part of the Canadian provinces of Alberta and Saskatchewan , eastern Central America , the islands of the Caribbean and the Gulf, and a small part of northern South America. The Mediterranean Sea basin, with the Black Sea , includes much of North Africa , east-central Africa (through the Nile River ), Southern , Central, and Eastern Europe , Turkey , and the coastal areas of Israel , Lebanon , and Syria . The Arctic Ocean drains most of Western Canada and Northern Canada east of

1890-629: A strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. About 48.71% of the world's land drains to the Atlantic Ocean . In North America , surface water drains to the Atlantic via the Saint Lawrence River and Great Lakes basins, the Eastern Seaboard of the United States, the Canadian Maritimes , and most of Newfoundland and Labrador . Nearly all of South America east of

1995-414: 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

2100-633: 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

2205-557: 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

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2310-584: Is located in the South Atlantic-Gulf Water Resource Region , which is listed as HUC 03. The basin is further sub-divided into 14 sub-basins. The ACF River Basin begins in the mountains of northeast Georgia , and drains much of metro Atlanta , most of west Georgia and southwest Georgia and adjoining counties of southeast Alabama , before it splits the central part of the Florida Panhandle and flows into

2415-487: Is referred to as " watershed management ". In Brazil , the National Policy of Water Resources, regulated by Act n° 9.433 of 1997, establishes the drainage basin as the territorial division of Brazilian water management. When a river basin crosses at least one political border, either a border within a nation or an international boundary, it is identified as a transboundary river . Management of such basins becomes

2520-614: Is the Dead Sea . Drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important. For example, the English crown gave the Hudson's Bay Company a monopoly on the fur trade in the entire Hudson Bay basin, an area called Rupert's Land . Bioregional political organization today includes agreements of states (e.g., international treaties and, within

2625-459: 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

2730-713: The African Great Lakes , the interiors of Australia and the Arabian Peninsula , and parts in Mexico and the Andes . Some of these, such as the Great Basin, are not single drainage basins but collections of separate, adjacent closed basins. In endorheic bodies of water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this

2835-464: The Andes also drains to the Atlantic, as does most of Western and Central Europe and the greatest portion of western Sub-Saharan Africa , as well as Western Sahara and part of Morocco . The two major mediterranean seas of the world also flow to the Atlantic. The Caribbean Sea and Gulf of Mexico basin includes most of the U.S. interior between the Appalachian and Rocky Mountains ,

2940-944: 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

3045-765: The Continental Divide , northern Alaska and parts of North Dakota , South Dakota , Minnesota , and Montana in the United States, the north shore of the Scandinavian peninsula in Europe, central and northern Russia, and parts of Kazakhstan and Mongolia in Asia , which totals to about 17% of the world's land. Just over 13% of the land in the world drains to the Pacific Ocean . Its basin includes much of China, eastern and southeastern Russia, Japan,

3150-876: 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

3255-529: 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

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3360-690: 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

3465-649: The Gulf of Mexico at Apalachicola Bay , near Apalachicola, Florida . It drains an area of 20,355 square miles. Most of the northern half of the basin abuts the Eastern Continental Divide on the east, and the ACT River Basin to the west. These states and Alabama have been involved in a water-use dispute for two decades, known as the Tri-state water dispute . Georgia has also lobbied

3570-714: The Korean Peninsula , most of Indochina, Indonesia and Malaysia, the Philippines, all of the Pacific Islands , the northeast coast of Australia , and Canada and the United States west of the Continental Divide (including most of Alaska), as well as western Central America and South America west of the Andes. The Indian Ocean 's drainage basin also comprises about 13% of Earth's land. It drains

3675-521: 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

3780-693: The United States Congress to end navigation on the Appalachicola and lower Chattahoochee, to conserve more water during droughts. Keeping the two rivers at a navigable depth during these times requires large releases from dams upstream, sending potential drinking water downstream for shipping, and often dropping lakes to levels dangerous to boaters. Other ecological conservation and economic concerns include protecting harvests of oysters in Apalachicola Bay, which require

3885-510: 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

3990-661: The groundwater . A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. Great Lakes 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

4095-414: 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

4200-584: 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

4305-632: 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

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4410-497: 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

4515-407: 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

4620-459: 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

4725-441: 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

4830-438: 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

4935-561: 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

5040-509: 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

5145-427: 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

5250-623: The US, interstate compacts ) or other political entities in a particular drainage basin to manage the body or bodies of water into which it drains. Examples of such interstate compacts are the Great Lakes Commission and the Tahoe Regional Planning Agency . In hydrology , the drainage basin is a logical unit of focus for studying the movement of water within the hydrological cycle . The process of finding

5355-495: 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

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5460-459: 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

5565-432: 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

5670-406: The basin, it can form tributaries that change the structure of the land. There are three different main types, which are affected by the rocks and ground underneath. Rock that is quick to erode forms dendritic patterns, and these are seen most often. The two other types of patterns that form are trellis patterns and rectangular patterns. Rain gauge data is used to measure total precipitation over

5775-635: 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

5880-427: 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

5985-779: 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

6090-430: The discharge of water from a basin may be made by a stream gauge located at the basin's outlet. Depending on the conditions of the drainage basin, as rainfall occurs some of it seeps directly into the ground. This water will either remain underground, slowly making its way downhill and eventually reaching the basin, or it will permeate deeper into the soil and consolidate into groundwater aquifers. As water flows through

6195-441: The drainage area is dependent on the soil type. Certain soil types such as sandy soils are very free-draining, and rainfall on sandy soil is likely to be absorbed by the ground. However, soils containing clay can be almost impermeable and therefore rainfall on clay soils will run off and contribute to flood volumes. After prolonged rainfall even free-draining soils can become saturated , meaning that any further rainfall will reach

6300-642: The drainage basin to the mouth, and may accumulate there, disturbing the natural mineral balance. This can cause eutrophication where plant growth is accelerated by the additional material. Because drainage basins are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins. In the U.S. state of Minnesota , governmental entities that perform this function are called " watershed districts ". In New Zealand, they are called catchment boards. Comparable community groups based in Ontario, Canada, are called conservation authorities . In North America, this function

6405-432: The eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf , the Indian subcontinent , Burma, and most parts of Australia . The five largest river basins (by area), from largest to smallest, are those of the Amazon (7 million km ), the Congo (4 million km ), the Nile (3.4 million km ), the Mississippi (3.22 million km ), and the Río de la Plata (3.17 million km ). The three rivers that drain

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6510-401: 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

6615-443: 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 ,

6720-443: 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

6825-471: 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

6930-417: 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

7035-435: The ground and along rivers it can pick up nutrients , sediment , and pollutants . With the water, they are transported towards the outlet of the basin, and can affect the ecological processes along the way as well as in the receiving water body . Modern use of artificial fertilizers , containing nitrogen (as nitrates ), phosphorus , and potassium , has affected the mouths of drainage basins. The minerals are carried by

7140-422: The ground at its terminus, the area can go by several names, such playa, salt flat, dry lake , or alkali sink . The largest endorheic basins are in Central Asia , including the Caspian Sea , the Aral Sea , and numerous smaller lakes. Other endorheic regions include the Great Basin in the United States, much of the Sahara Desert , the drainage basin of the Okavango River ( Kalahari Basin ), highlands near

7245-410: 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

7350-442: 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

7455-483: 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

7560-612: 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

7665-650: 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

7770-538: 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

7875-470: 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

7980-408: 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

8085-415: 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

8190-468: 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

8295-494: 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

8400-514: The most water, from most to least, are the Amazon, Ganges , and Congo rivers. Endorheic basin are inland basins that do not drain to an ocean. Endorheic basins cover around 18% of the Earth's land. Some endorheic basins drain to an Endorheic lake or Inland sea . Many of these lakes are ephemeral or vary dramatically in size depending on climate and inflow. If water evaporates or infiltrates into

8505-476: 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,

8610-467: 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

8715-516: 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

8820-516: 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

8925-418: The rainfall on the area of land included in its polygon. These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons. The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map. Calculating the area between these curves and adding up the volume of water is time-consuming. Isochrone maps can be used to show

9030-631: The responsibility of the countries sharing it. Nile Basin Initiative , OMVS for Senegal River , Mekong River Commission are a few examples of arrangements involving management of shared river basins. Management of shared drainage basins is also seen as a way to build lasting peaceful relationships among countries. The catchment is the most significant factor determining the amount or likelihood of flooding . Catchment factors are: topography , shape, size, soil type, and land use (paved or roofed areas). Catchment topography and shape determine

9135-461: The river rather than being absorbed by the ground. If the surface is impermeable the precipitation will create surface run-off which will lead to higher risk of flooding; if the ground is permeable, the precipitation will infiltrate the soil. Land use can contribute to the volume of water reaching the river, in a similar way to clay soils. For example, rainfall on roofs, pavements , and roads will be collected by rivers with almost no absorption into

9240-428: 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

9345-436: 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

9450-602: 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

9555-418: The speed with which the runoff reaches a river. A long thin catchment will take longer to drain than a circular catchment. Size will help determine the amount of water reaching the river, as the larger the catchment the greater the potential for flooding. It is also determined on the basis of length and width of the drainage basin. Soil type will help determine how much water reaches the river. The runoff from

9660-414: 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

9765-415: The time taken for rain to reach the river, while catchment size, soil type, and development determine the amount of water to reach the river. Generally, topography plays a big part in how fast runoff will reach a river. Rain that falls in steep mountainous areas will reach the primary river in the drainage basin faster than flat or lightly sloping areas (e.g., > 1% gradient). Shape will contribute to

9870-477: The time taken for runoff water within a drainage basin to reach a lake, reservoir or outlet, assuming constant and uniform effective rainfall. Drainage basins are the principal hydrologic unit considered in fluvial geomorphology . A drainage basin is the source for water and sediment that moves from higher elevation through the river system to lower elevations as they reshape the channel forms. Drainage basins are important in ecology . As water flows over

9975-562: 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,

10080-532: 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

10185-416: 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

10290-430: 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,

10395-427: 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

10500-480: 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

10605-472: 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,

10710-567: 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

10815-523: 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

10920-558: 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

11025-517: 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

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