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106-921: The Potomac River ( / p ə ˈ t oʊ m ə k / ) is a major river in the Mid-Atlantic region of the United States that flows from the Potomac Highlands in West Virginia to the Chesapeake Bay in Maryland . It is 405 miles (652 km) long, with a drainage area of 14,700 square miles (38,000 km), and is the fourth-largest river along the East Coast of the United States . More than 6 million people live within its watershed . The river forms part of

212-594: A few of West Virginia's eastern panhandle counties are considered part of the Washington metropolitan area , the major portion of the state is rural and there are no major or even large cities. Shipping and trade have been important to the Mid-Atlantic economy since the beginning of the colonial era. The explorer Giovanni da Verrazzano was the first European to see the region in 1524. Henry Hudson later extensively explored that region in 1611 and claimed it for

318-421: A free connection to the open sea . Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone . Estuaries are subject both to marine influences such as tides , waves , and the influx of saline water , and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in

424-573: A harsh environment for organisms. Sediment often settles in intertidal mudflats which are extremely difficult to colonize. No points of attachment exist for algae , so vegetation based habitat is not established. Sediment can also clog feeding and respiratory structures of species, and special adaptations exist within mudflat species to cope with this problem. Lastly, dissolved oxygen variation can cause problems for life forms. Nutrient-rich sediment from human-made sources can promote primary production life cycles, perhaps leading to eventual decay removing

530-547: A map and published in London in 1612. This detail from that map shows his rendition of the river that the local tribes had told him was called the "Patawomeck". The spelling of the name has taken many forms over the years from " Patawomeck " (as on Captain John Smith 's map) to "Patomake", "Patowmack", and numerous other variations in the 18th century and now "Potomac". The river's name was officially decided upon as "Potomac" by

636-529: A number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible". This broad definition also includes fjords , lagoons , river mouths , and tidal creeks . An estuary

742-630: A series of large islands while it heads northeast to Moorefield . At Moorefield, the South Branch is joined by the South Fork South Branch Potomac River and runs north to Old Fields where it is fed by Anderson Run and Stony Run. At McNeill , the South Branch flows into the Trough where it is bound to its west by Mill Creek Mountain (2,119 ft) and to its east by Sawmill Ridge (1,644 ft). This area

848-664: A serpentine path through the eastern Allegheny Mountains. First, it flows northeast by the communities of Bloomington , Luke , and Westernport in Maryland and then on by Keyser , West Virginia to Cumberland , Maryland. At Cumberland, the river turns southeast. 103 miles (166 km) downstream from its source, the North Branch is joined by the South Branch between Green Spring and South Branch Depot , West Virginia from whence it flows past Hancock , Maryland and turns southeast once more on its way toward Washington, D.C. , and

954-688: A sub-region of the Northeast and only includes New Jersey, New York, and Pennsylvania. The Bureau of Labor Statistics excludes New York; the Environmental Protection Agency excludes New York and New Jersey; and the U.S. Department of Transportation - United States Maritime Administration includes North Carolina . In 2004, the United States Geological Survey within the context of Ground-Water Vulnerability to Nitrate Contamination, defined

1060-521: A time, New Sweden along the Delaware River in Delaware , divided the two great bulwarks of English settlement from each other. The original English settlements in the region notably provided refuge to religious minorities, Maryland to Roman Catholics and Pennsylvania to Quakers and Anabaptist Pennsylvania Dutch . In time, all these settlements fell under English colonial control, but

1166-408: A type of ecosystem in some estuaries that have been negatively impacted by eutrophication. Cordgrass vegetation dominates the salt marsh landscape. Excess nutrients allow the plants to grow at greater rates in above ground biomass, however less energy is allocated to the roots since nutrients is abundant. This leads to a lower biomass in the vegetation below ground which destabilizes the banks of

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1272-661: A water intake 725 feet (220 m) offshore, citing potential harm to Maryland's interests by an increase in Virginia sprawl caused by the project. After years of failed appeals within the Maryland government's appeal processes, in 2000 Virginia took the case to the Supreme Court of the United States , which exercises original jurisdiction in cases between two states. Maryland claimed Virginia lost its riparian rights by acquiescing to MDE's permit process for 63 years (MDE began its permit process in 1933). A Special Master appointed by

1378-563: A well-mixed water column and the disappearance of the vertical salinity gradient . The freshwater-seawater boundary is eliminated due to the intense turbulent mixing and eddy effects . The lower reaches of Delaware Bay and the Raritan River in New Jersey are examples of vertically homogeneous estuaries. Inverse estuaries occur in dry climates where evaporation greatly exceeds the inflow of freshwater. A salinity maximum zone

1484-436: A wholly marine embayment to any of the other estuary types. The most important variable characteristics of estuary water are the concentration of dissolved oxygen, salinity and sediment load. There is extreme spatial variability in salinity, with a range of near-zero at the tidal limit of tributary rivers to 3.4% at the estuary mouth. At any one point, the salinity will vary considerably over time and seasons, making it

1590-414: A wide effect on the surrounding water bodies.  In turn, this can decrease fishing industry sales in one area and across the country. Production in 2016 from recreational and commercial fishing contributes billions of dollars to the United States' gross domestic product (GDP). A decrease in production within this industry can affect any of the 1.7 million people the fishing industry employs yearly across

1696-455: Is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides . The effects of tides on estuaries can show nonlinear effects on the movement of water which can have important impacts on the ecosystem and waterflow. The seawater entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on

1802-550: Is also home to the nation's capital, Washington, D.C. The Mid-Atlantic is home to 33 professional sports franchises in the five major leagues and the two most prominent women's professional leagues: Notable golf tournaments in the Mid-Atlantic include the Barclays , Quicken Loans National and Atlantic City LPGA Classic . Two high-level professional tennis tournaments are held in the region. The US Open , held in New York,

1908-500: Is at least 3.5 million years old, likely extending back ten to twenty million years before the present when the Atlantic Ocean lowered and exposed coastal sediments along the fall line. This included the area at Great Falls, which eroded into its present form during recent glaciation periods. The stream gradient of the entire river is 0.14%, a drop of 930 m over 652 km. "Potomac" is a European spelling of Patawomeck ,

2014-880: Is currently re-bounding as a result of the ICPRB 's successful "American Shad Restoration Project" that was begun in 1995. In addition to stocking the river with more than 22 million shad fry, the Project supervised the construction of a fishway that was built to facilitate the passage of adults around the Little Falls Dam on the way to their traditional spawning grounds upstream.   *denotes naturalized species; Sources: Striped mullet Mugil cephalus Spot Leiostomus xanthurus Spotted seatrout Cynoscion nebulosus Atlantic Croaker Micropogonias undulatus Mid-Atlantic (United States) The Mid-Atlantic region played an instrumental and historic role in

2120-513: Is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus , meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which seawater is measurably diluted with freshwater derived from land drainage". However, this definition excludes

2226-411: Is formed, and both riverine and oceanic water flow close to the surface towards this zone. This water is pushed downward and spreads along the bottom in both the seaward and landward direction. Examples of an inverse estuary are Spencer Gulf , South Australia, Saloum River and Casamance River , Senegal. Estuary type varies dramatically depending on freshwater input, and is capable of changing from

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2332-566: Is less restricted, and there is a slow but steady exchange of water between the estuary and the ocean. Fjord-type estuaries can be found along the coasts of Alaska , the Puget Sound region of western Washington state , British Columbia , eastern Canada, Greenland , Iceland , New Zealand, and Norway. These estuaries are formed by subsidence or land cut off from the ocean by land movement associated with faulting , volcanoes , and landslides . Inundation from eustatic sea-level rise during

2438-817: Is located on its banks, as is Mount Vernon , the home of "Father of his Country" George Washington . During the American Civil War, the river became the boundary between the Union and the Confederacy , and the Union's largest army, the Army of the Potomac , was named after the river. The Potomac River runs 405 mi (652 km) from Fairfax Stone Historical Monument State Park in West Virginia on

2544-693: Is one of the four Grand Slam tennis tournaments, whereas the Washington Open is part of the ATP Tour 500 series and WTA 250 series. Notable motorsports tracks include Watkins Glen International , Dover Motor Speedway and Pocono Raceway , which have hosted Formula One , IndyCar , NASCAR , World Sportscar Championship and IMSA races. Also, the Englishtown and Reading drag strips such have hosted NHRA national events. Pimlico Race Course at Baltimore and Belmont Park at New York host

2650-402: Is said that President Abraham Lincoln used to escape to the highlands on summer nights to escape the river's stench. In the 1960s, with dense green algal blooms covering the river's surface, President Lyndon Johnson declared the river "a national disgrace" and set in motion a long-term effort to reduce pollution from sewage and restore the beauty and ecology of this historic river. One of

2756-443: Is the habitat to bald eagles . The Trough passes into Hampshire County and ends at its confluence with Sawmill Run south of Glebe and Sector . The South Branch continues north parallel to South Branch River Road ( County Route 8) toward Romney with a number of historic plantation farms adjoining it. En route to Romney, the river is fed by Buffalo Run, Mill Run , McDowell Run, and Mill Creek at Vanderlip . The South Branch

2862-646: Is the whitefish species from the European Alps . Eutrophication reduced the oxygen levels in their habitats so greatly that whitefish eggs could not survive, causing local extinctions. However, some animals, such as carnivorous fish, tend to do well in nutrient-enriched environments and can benefit from eutrophication. This can be seen in populations of bass or pikes. Eutrophication can affect many marine habitats which can lead to economic consequences. The commercial fishing industry relies upon estuaries for approximately 68 percent of their catch by value because of

2968-526: Is traversed by the Northwestern Turnpike ( U.S. Route 50 ) and joined by Sulphur Spring Run where it forms Valley View Island to the west of town. Flowing north of Romney, the river still follows the eastern side of Mill Creek Mountain until it creates a horseshoe bend at Wappocomo 's Hanging Rocks around the George W. Washington plantation, Ridgedale . To the west of Three Churches on

3074-532: The Algonquian name of a Native American village on its southern bank. Native Americans had different names for different parts of the river, calling the river above Great Falls Cohongarooton , meaning "honking geese" and "Patawomke" below the Falls, meaning "river of swans". In 1608, Captain John Smith explored the river now known as the Potomac and made drawings of his observations which were later compiled into

3180-543: The Allegheny Plateau to Point Lookout , Maryland, and drains 14,679 sq mi (38,020 km). The length of the river from the junction of its North and South Branches to Point Lookout is 302 mi (486 km). The river has two sources. The source of the North Branch is at the Fairfax Stone located at the junction of Grant , Tucker , and Preston counties in West Virginia . The source of

3286-807: The Atlantic coastal plain . Once the Potomac drops from the Piedmont to the Coastal Plain at the Atlantic Seaboard fall line at Little Falls , tides further influence the river as it passes through Washington, D.C., and beyond. Salinity in the Potomac River Estuary increases thereafter with distance downstream. The estuary also widens, reaching 11 statute miles (17 km) wide at its mouth, between Point Lookout, Maryland, and Smith Point , Virginia, before flowing into

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3392-518: The Board on Geographic Names in 1931. The similarity of the name to the Ancient Greek word for river, potamos , has been noted for more than two centuries but it appears to be due to chance. The Potomac River brings together a variety of cultures throughout the watershed from the coal miners of upstream West Virginia to the urban residents of the nation's capital and, along the lower Potomac,

3498-516: The Chesapeake Bay . The exact location of the South Branch's source is northwest of Hightown along U.S. Route 250 on the eastern side of Lantz Mountain (3,934 ft) in Highland County. From Hightown, the South Branch is a small meandering stream that flows northeast along Blue Grass Valley Road through the communities of New Hampden and Blue Grass . At Forks of Waters , the South Branch joins with Strait Creek and flows north across

3604-899: The Continental Congress , the convention of delegates who organized the American Revolution . Philadelphia also was the birthplace of the Declaration of Independence in 1776 and the United States Constitution in 1787, while the United States Bill of Rights was drafted and ratified and the first Supreme Court of the United States sat for the first time, in the first capital under the Constitution of New York . While early settlers were mostly farmers, traders, and fishermen,

3710-1486: The Fall Line . This 108-mile (174-km) stretch encompasses the Potomac from a short distance below the Washington, DC - Montgomery County line, just downstream of the Little Falls of the Potomac River , to the Chesapeake Bay . Along the way the following tributaries drain into the Potomac: Pimmit Run , Gulf Branch , Donaldson Run , Windy Run , Spout Run , Maddox Branch , Foundry Branch , Rock Creek , Rocky Run, Tiber Creek , Roaches Run, Washington Channel , Anacostia River , Four Mile Run , Oxon Creek , Hunting Creek , Broad Creek , Henson Creek, Swan Creek, Piscataway Creek , Little Hunting Creek , Dogue Creek , Accotink Creek , Pohick Creek , Pomonkey Creek , Occoquan River , Neabsco Creek , Powell's Creek , Mattawoman Creek , Chicamuxen Creek , Quantico Creek , Little Creek , Chopawamsic Creek , Tank Creek , Aquia Creek , Potomac Creek , Nanjemoy Creek , Chotank Creek , Port Tobacco River , Popes Creek , Gambo Creek , Clifton Creek , Piccowaxen Creek , Upper Machodoc Creek , Wicomico River , Cobb Island , Monroe Creek , Mattox Creek , Popes Creek , Breton Bay, Leonardtown , St. Marys River , Yeocomico River , Coan River , and Hull Creek . The river itself

3816-748: The Holocene Epoch has also contributed to the formation of these estuaries. There are only a small number of tectonically produced estuaries; one example is the San Francisco Bay , which was formed by the crustal movements of the San Andreas Fault system causing the inundation of the lower reaches of the Sacramento and San Joaquin rivers . In this type of estuary, river output greatly exceeds marine input and tidal effects have minor importance. Freshwater floats on top of

3922-562: The Interstate Commission on the Potomac River Basin . The compact was amended in 1970 to include coordination of water supply issues and land use issues related to water quality. Beginning in the 19th century, with increasing mining and agriculture upstream and urban sewage and runoff downstream, the water quality of the Potomac River deteriorated. This created conditions of severe eutrophication . It

4028-547: The Mandovi estuary in Goa during the monsoon period. As tidal forcing increases, river output becomes less than the marine input. Here, current induced turbulence causes mixing of the whole water column such that salinity varies more longitudinally rather than vertically, leading to a moderately stratified condition. Examples include the Chesapeake Bay and Narragansett Bay . Tidal mixing forces exceed river output, resulting in

4134-580: The Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast . Bar-built estuaries are found in a place where the deposition of sediment has kept pace with rising sea levels so that the estuaries are shallow and separated from the sea by sand spits or barrier islands. They are relatively common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches ( barrier islands and barrier spits ). Formation of barrier beaches partially encloses

4240-674: The Preakness Stakes and Belmont Stakes horse races, which are part of the Triple Crown of Thoroughbred Racing . With a GDP nominal of over $ 5.2 trillion, the Mid-Atlantic economy would be third-largest in the world if calculated separately, only behind the remaining United States and China and nearly $ 1 trillion larger than next place Japan. This economic prosperity is buoyed by a significant financial services and banking sector, healthcare and chemicals industry, and telecommunications and entertainment conglomerates. According to

4346-734: The Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River , Chesapeake Bay , and Delaware Bay along

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4452-617: The US Geological Survey and the Fish and Wildlife Service , began to identify fish in the Potomac and tributaries that exhibited "intersex" characteristics, as a result of endocrine disruption caused by some form of pollution. On November 13, 2007, the Potomac Conservancy, an environmental group, issued the river a grade of "D-plus", citing high levels of pollution and the reports of " intersex " fish. Since then,

4558-741: The University of Pennsylvania in Philadelphia ; Carnegie Mellon University in Pittsburgh ; Johns Hopkins University in Baltimore , Georgetown University in Washington, D.C. ; and the University of Virginia in Charlottesville, Virginia according to U.S. News & World Report Best Colleges Ranking . Definitions of the geographic components of the Mid-Atlantic region differ slightly among sources. Generally speaking,

4664-478: The black-tailed godwit , rely on estuaries. Two of the main challenges of estuarine life are the variability in salinity and sedimentation . Many species of fish and invertebrates have various methods to control or conform to the shifts in salt concentrations and are termed osmoconformers and osmoregulators . Many animals also burrow to avoid predation and to live in a more stable sedimental environment. However, large numbers of bacteria are found within

4770-546: The 1980s, through sewage plant upgrades and restrictions on phosphorus in detergents. By the end of the 20th century, notable success had been achieved, as massive algal blooms vanished and recreational fishing and boating rebounded. Still, the aquatic habitat of the Potomac River and its tributaries remain vulnerable to eutrophication, heavy metals , pesticides and other toxic chemicals, over-fishing, alien species , and pathogens associated with fecal coliform bacteria and shellfish diseases. In 2005 two federal agencies,

4876-702: The Chesapeake Bay. The source of the North Branch Potomac River is at the Fairfax Stone located at the junction of Grant , Tucker and Preston counties in West Virginia. From the Fairfax Stone, the North Branch Potomac River flows 27 mi (43 km) to the man-made Jennings Randolph Lake , an impoundment designed for flood control and emergency water supply. Below the dam, the North Branch cuts

4982-778: The Dutch, who then created a fur-trading post in Albany in 1614. Jamestown, Virginia was the first permanent English colony in North America, it was established seven years earlier in 1607. From early colonial times, the Mid-Atlantic region was settled by a wider range of European people than in New England or the South. The Dutch New Netherland settlement along the Hudson River in New York City and New Jersey , and for

5088-408: The Global Financial Centres Index, the Mid-Atlantic region is home to the leading financial center in the world (New York) at #1, with Washington also present at #15. Notable companies (over $ 100 billion market cap) headquartered in the region include: Estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with

5194-430: The Mid-Atlantic states provided the young United States with heavy industry and served as the " melting pot " of new immigrants from Europe. Cities grew along major ports, shipping routes, and waterways, including New York City and Newark on opposite sides of the Hudson River , Philadelphia on the Delaware River, Allentown on the Lehigh River , and Baltimore on the Chesapeake Bay . Note: The Mid-Atlantic region

5300-472: The Mid-Atlantic, and 33 of the nation's top 100 counties based on per capita income are in the region. Most of the Mid-Atlantic states rank among the 15 highest-income states in the nation by both median household income and per capita income. The region is home to eight of the top 25 ranked universities in the nation: Cornell University in Ithaca, New York ; Columbia University and NYU in New York City; Princeton University in Princeton, New Jersey ;

5406-437: The Potomac and its North Branch since both states' original colonial charters grant the entire river rather than half of it as is normally the case with boundary rivers. In its first state constitution adopted in 1776, Virginia ceded its claim to the entire river but reserved free use of it, an act disputed by Maryland. Both states acceded to the 1785 Mount Vernon Compact and the 1877 Black-Jenkins Award which granted Maryland

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5512-439: The Potomac as its principal source of drinking water with the opening of the Washington Aqueduct in 1864, using a water intake constructed at Great Falls. An average of approximately 486 million US gallons (1,840,000 m) of water is withdrawn daily from the Potomac in the Washington area for water supply , providing about 78 percent of the region's total water usage, this amount includes approximately 80 percent of

5618-799: The Potomac from just above Harpers Ferry in West Virginia down to Little Falls, Maryland on the border between Maryland and Washington, DC. Along the way the following tributaries drain into the Potomac: Antietam Creek , Shenandoah River , Catoctin Creek (Virginia) , Catoctin Creek (Maryland) , Tuscarora Creek , Monocacy River , Little Monocacy River , Broad Run , Goose Creek , Broad Run , Horsepen Branch, Little Seneca Creek , Tenmile Creek , Great Seneca Creek , Old Sugarland Run, Muddy Branch , Nichols Run, Watts Branch , Limekiln Branch, Carroll Branch, Pond Run, Clarks Branch, Mine Run Branch, Difficult Run , Bullneck Run, Rock Run , Scott Run, Dead Run, Turkey Run, Cabin John Creek , Minnehaha Branch, and Little Falls Branch . The Tidal Potomac River lies below

5724-407: The Potomac, including bass , muskellunge , pike , walleye . The northern snakehead , an invasive species resembling the native bowfin , lamprey , and American eel , was first seen in 2004. Many species of sunfish are also present in the Potomac and its headwaters. Although rare, bull sharks can be found. After having been depressed for many decades, the river's population of American shad

5830-406: The South Branch continues north through the Monongahela National Forest to Upper Tract where it joins with three sizeable streams: Reeds Creek, Mill Run, and Deer Run. Between Big Mountain (2,582 ft) and Cave Mountain (2,821 ft), the South Branch bends around the Eagle Rock (1,483 ft) outcrop and continues its flow northward into Grant County . Into Grant, the South Branch follows

5936-413: The South Branch is located near Hightown in northern Highland County , Virginia. The river's two branches converge just east of Green Spring in Hampshire County , West Virginia, to form the Potomac. As it flows from its headwaters down to the Chesapeake Bay, the Potomac traverses five geological provinces: the Appalachian Plateau , the Ridge and Valley , the Blue Ridge , the Piedmont Plateau , and

6042-453: The Supreme Court to investigate recommended the case be settled in favor of Virginia, citing the language in the 1785 Compact and the 1877 Award. On December 9, 2003, the Court agreed in a 7–2 decision. The original charters are silent as to which branch from the upper Potomac serves as the boundary, but this was settled by the 1785 Compact. When West Virginia seceded from Virginia in 1863, the question of West Virginia's succession in title to

6148-518: The United States . The nation's capital was constructed in Washington, D.C. in the late 18th century, and relocated there from Philadelphia in 1800. In the early part of the 19th century, New York and Pennsylvania overtook Virginia as the nation's two most populous states, and the Mid-Atlantic region overtook New England as the most important trading and industrial center in the nation. During this period, large numbers of German , Irish , Italian , Jewish , Polish , and other immigrants arrived in

6254-400: The United States. Estuaries are incredibly dynamic systems, where temperature, salinity, turbidity, depth and flow all change daily in response to the tides. This dynamism makes estuaries highly productive habitats, but also make it difficult for many species to survive year-round. As a result, estuaries large and small experience strong seasonal variation in their fish communities. In winter,

6360-458: The Virginia side of the river, it was not completed until 1802. Financial troubles led to the closure of the canal in 1830. The Chesapeake and Ohio Canal operated along the banks of the Potomac in Maryland from 1831 to 1924 and also connected Cumberland to Washington, D.C. This allowed freight to be transported around the rapids known as the Great Falls of the Potomac River , as well as many other, smaller rapids. Washington, D.C. began using

6466-432: The Virginia/West Virginia border into Pendleton County . The river then travels on a northeastern course along the western side of Jack Mountain (4,045 ft), followed by Sandy Ridge (2,297 ft) along U.S. Route 220 . North of the confluence of the South Branch with Smith Creek, the river flows along Town Mountain (2,848 ft) around Franklin at the junction of U.S. Route 220 and U.S. Route 33 . After Franklin,

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6572-513: The above definition of an estuary and could be fully saline. Many estuaries suffer degeneration from a variety of factors including soil erosion , deforestation , overgrazing , overfishing and the filling of wetlands. Eutrophication may lead to excessive nutrients from sewage and animal wastes; pollutants including heavy metals , polychlorinated biphenyls , radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion. The word "estuary"

6678-483: The battles of Antietam (September 17, 1862) and Gettysburg (July 1–3, 1863). Confederate General Jubal Early crossed the river in July 1864 on his attempted raid on the nation's capital. The river not only divided the Union from the Confederacy, but also gave name to the Union's largest army, the Army of the Potomac . The Patowmack Canal was intended by George Washington to connect the Tidewater region near Georgetown with Cumberland , Maryland. Started in 1785 on

6784-473: The borders between Maryland and Washington, D.C. , on the left descending bank, and West Virginia and Virginia on the right descending bank. Except for a small portion of its headwaters in West Virginia, the North Branch Potomac River is considered part of Maryland to the low-water mark on the opposite bank. The South Branch Potomac River lies completely within the state of West Virginia except for its headwaters , which lie in Virginia. All navigable parts of

6890-452: The bottom where they are harmless. Historically the oysters filtered the estuary's entire water volume of excess nutrients every three or four days. Today that process takes almost a year, and sediment, nutrients, and algae can cause problems in local waters. Some major rivers that run through deserts historically had vast, expansive estuaries that have been reduced to a fraction of their former size, because of dams and diversions. One example

6996-413: The catching near Fletcher's Boat House of a Striped Bass estimated to weigh 35 lb (16 kg) was seen as a further indicator of the continuing improvement in the health of the river. The average daily flow during the water years 1931–2018 was 11,498 cubic feet (325.6 m) /s. The highest average daily flow ever recorded on the Potomac at Little Falls, Maryland (near Washington, D.C.),

7102-409: The dissolved oxygen from the water; thus hypoxic or anoxic zones can develop. Nitrogen is often the lead cause of eutrophication in estuaries in temperate zones. During a eutrophication event, biogeochemical feedback decreases the amount of available silica . These feedbacks also increase the supply of nitrogen and phosphorus, creating conditions where harmful algal blooms can persist. Given

7208-442: The drinking water consumed by the region's estimated 6.1 million residents. As a result of damaging floods in 1936 and 1937, the Army Corps of Engineers proposed the Potomac River basin reservoir projects , a series of dams that were intended to regulate the river and to provide a more reliable water supply. One dam was to be built at Little Falls, just north of Washington, backing its pool up to Great Falls. Just above Great Falls,

7314-401: The effects of modifying the estuarine circulation. Fjord -type estuaries are formed in deeply eroded valleys formed by glaciers . These U-shaped estuaries typically have steep sides, rock bottoms, and underwater sills contoured by glacial movement. The estuary is shallowest at its mouth, where terminal glacial moraines or rock bars form sills that restrict water flow. In the upper reaches of

7420-543: The estuary impacted by human activities, and over time may shift the basic composition of the ecosystem, and the reversible or irreversible changes in the abiotic and biotic parts of the systems from the bottom up. For example, Chinese and Russian industrial pollution, such as phenols and heavy metals, has devastated fish stocks in the Amur River and damaged its estuary soil. Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries. With human activities, land run-off also now includes

7526-424: The estuary, the depth can exceed 300 m (1,000 ft). The width-to-depth ratio is generally small. In estuaries with very shallow sills, tidal oscillations only affect the water down to the depth of the sill, and the waters deeper than that may remain stagnant for a very long time, so there is only an occasional exchange of the deep water of the estuary with the ocean. If the sill depth is deep, water circulation

7632-776: The estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U.S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m (13 ft). The barrier beaches that enclose bar-built estuaries have been developed in several ways: Fjords were formed where Pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross-sections. At their mouths there are typically rocks, bars or sills of glacial deposits , which have

7738-609: The fish community is dominated by hardy marine residents, and in summer a variety of marine and anadromous fishes move into and out of estuaries, capitalizing on their high productivity. Estuaries provide a critical habitat to a variety of species that rely on estuaries for life-cycle completion. Pacific Herring ( Clupea pallasii ) are known to lay their eggs in estuaries and bays, surfperch give birth in estuaries, juvenile flatfish and rockfish migrate to estuaries to rear, and anadromous salmonids and lampreys use estuaries as migration corridors. Also, migratory bird populations, such as

7844-400: The great biodiversity of this ecosystem. During an algal bloom , fishermen have noticed a significant increase in the quantity of fish. A sudden increase in primary productivity causes spikes in fish populations which leads to more oxygen being utilized. It is the continued deoxygenation of the water that then causes a decline in fish populations. These effects can begin in estuaries and have

7950-420: The impacts do not end there. Plant death alters the entire food web structure which can result in the death of animals within the afflicted biome . Estuaries are hotspots for biodiversity , containing a majority of commercial fish catch, making the impacts of eutrophication that much greater within estuaries. Some specific estuarine animals feel the effects of eutrophication more strongly than others. One example

8056-484: The lands between the branches of the river was raised, as well as title to the river itself. Claims by Maryland to West Virginia land north of the South Branch (all of Mineral and Grant Counties and parts of Hampshire , Hardy , Tucker and Pendleton Counties) and by West Virginia to the Potomac's high-water mark were rejected by the Supreme Court in two separate decisions in 1910. A variety of fish inhabit

8162-525: The many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. Excess oxygen-depleting chemicals in the water can lead to hypoxia and the creation of dead zones . This can result in reductions in water quality, fish, and other animal populations. Overfishing also occurs. Chesapeake Bay once had a flourishing oyster population that has been almost wiped out by overfishing. Oysters filter these pollutants, and either eat them or shape them into small packets that are deposited on

8268-422: The marine environment, such as plastics , pesticides , furans , dioxins , phenols and heavy metals . Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation . They also accumulate in benthic environments, such as estuaries and bay muds : a geological record of human activities of the last century. The elemental composition of biofilm reflect areas of

8374-575: The marsh causing increased rates of erosion . A similar phenomenon occurs in mangrove swamps , which are another potential ecosystem in estuaries. An increase in nitrogen causes an increase in shoot growth and a decrease in root growth. Weaker root systems cause a mangrove tree to be less resilient in seasons of drought, which can lead to the death of the mangrove. This shift in above ground and below ground biomass caused by eutrophication could hindered plant success in these ecosystems. Across all biomes, eutrophication often results in plant death but

8480-504: The much larger Seneca Dam was proposed whose reservoir would extend to Harpers Ferry. Several other dams were proposed for the Potomac and its tributaries. Operational Non-Operational Planned, but never built When detailed studies were issued by the Corps in the 1950s, they met sustained opposition, led by U.S. Supreme Court Justice William O. Douglas , resulting in the plans' abandonment. The only dam project that did get built

8586-650: The nation's capital was to be located on the river. The 1859 siege of Harper's Ferry at the river's confluence with the Shenandoah was a precursor to numerous epic battles of the American Civil War in and around the Potomac and its tributaries, such as the 1861 Battle of Ball's Bluff and the 1862 Battle of Shepherdstown . General Robert E. Lee crossed the river, thereby invading the North and threatening Washington, D.C., twice in campaigns climaxing in

8692-703: The nation's founding and the development of the nation. Each of the seven states were members of the Thirteen Colonies that sent delegates to the Second Continental Congress , which assembled in Philadelphia and unanimously adopted the Declaration of Independence , and formalized the Continental Army under George Washington 's command during the American Revolutionary War . Following independence,

8798-440: The now off-balance nitrogen cycle , estuaries can be driven to phosphorus limitation instead of nitrogen limitation. Estuaries can be severely impacted by an unbalanced phosphorus cycle, as phosphorus interacts with nitrogen and silica availability. With an abundance of nutrients in the ecosystem, plants and algae overgrow and eventually decompose, which produce a significant amount of carbon dioxide. While releasing CO 2 into

8904-611: The original Thirteen Colonies and were particularly prevalent in Province of Pennsylvania and the geographic region that ultimately broke from Pennsylvania to form the Delaware Colony . Among the 13 colonies, the Province of Maryland was the only colony with a substantial Catholic population. Following the American Revolutionary War, the Mid-Atlantic region hosted each of the historic capitals of

9010-520: The region as including Delaware, Maryland, Pennsylvania, Virginia, and Washington, D.C., and parts of New Jersey, New York, and North Carolina. West Virginia and Virginia are atypical of this region in a few ways. These states both primarily lie within the Southern American dialect region , and the major religious tradition is largely Evangelical Christian , with 30% in Virginia and 39% in West Virginia identifying as evangelicals. Although

9116-467: The region continued to be a magnet for people of diverse nationalities. The area that came to be known as the Middle Colonies served as a strategic bridge between the North and South. The New York and New Jersey campaign during the American Revolutionary War saw more battles than any other theater of the conflict. Philadelphia , midway between the northern and southern colonies, was home to

9222-579: The region is inclusive of the states of Delaware, Maryland, New Jersey, New York, Pennsylvania, Virginia, and West Virginia, and the federal district of the District of Columbia, with some additional sources including or excluding other areas in parts of the Northeast region and the South Atlantic states , for practical reasons. The United States Census Bureau defines the Mid-Atlantic as

9328-451: The region link an almost contiguous urban region, which includes large and small cities and their respective suburbs and forms the Northeast megalopolis , one of the world's most important concentrations of finance, media, communications, education , medicine, and technology. The Mid-Atlantic is a relatively affluent region of the nation; nearly half of the nation's 100 highest-income counties based on median household income are located in

9434-588: The region's coastal cities, including Baltimore , Newark , New York City , Philadelphia, and interior cities such as Pittsburgh , and Rochester , Albany , and Buffalo , with their skyscrapers and subways, which emerged as icons of modernity and American economic and cultural power in the 20th century. In the late 19th century, the region played a vital and historic role in the development of American culture , commerce, trade, and industry sectors . Historian Frederick Jackson Turner labeled it "typically American." The Northeast Corridor and Interstate 95 in

9540-677: The river bank-to-bank from the low-water mark on the Virginia side while permitting Virginia full riparian rights short of obstructing navigation. From 1957 to 1996, the Maryland Department of the Environment (MDE) routinely issued permits applied for by Virginia entities concerning the use of the Potomac. However, in 1996 the MDE denied a permit submitted by the Fairfax County Water Authority to build

9646-500: The river has improved with a reduction in nutrient runoff, return of fish populations, and land protection along the river. As a result, the same group issued a grade of "B" for 2017 and 2018. In March 2019, the Potomac Riverkeeper Network launched a laboratory boat dubbed the "Sea Dog", which will be monitoring water quality in the Potomac and providing reports to the public on a weekly basis; in that same month,

9752-622: The river were designated as a National Recreation Trail in 2006, and the National Oceanic and Atmospheric Administration designated an 18-square-mile (47 km) portion of the river in Charles County , Maryland, as the Mallows Bay–Potomac River National Marine Sanctuary in 2019. The river has significant historical and political significance, as the nation's capital of Washington, D.C.

9858-427: The seawater in a layer that gradually thins as it moves seaward. The denser seawater moves landward along the bottom of the estuary, forming a wedge-shaped layer that is thinner as it approaches land. As a velocity difference develops between the two layers, shear forces generate internal waves at the interface, mixing the seawater upward with the freshwater. An examples of a salt wedge estuary is Mississippi River and

9964-627: The section of the Potomac River from the confluence of its North and South Branches through Opequon Creek near Shepherdstown, West Virginia . Along the way the following tributaries drain into the Potomac: North Branch Potomac River , South Branch Potomac River , Town Creek , Little Cacapon River , Sideling Hill Creek , Cacapon River , Sir Johns Run , Warm Spring Run , Tonoloway Creek , Fifteenmile Creek , Sleepy Creek , Cherry Run , Back Creek , Conococheague Creek , and Opequon Creek . This section covers

10070-411: The sediment which has a very high oxygen demand. This reduces the levels of oxygen within the sediment often resulting in partially anoxic conditions, which can be further exacerbated by limited water flow. Phytoplankton are key primary producers in estuaries. They move with the water bodies and can be flushed in and out with the tides . Their productivity is largely dependent upon the turbidity of

10176-536: The significant pollution control projects at the time was the expansion of the Blue Plains Advanced Wastewater Treatment Plant , which serves Washington and several surrounding communities. Enactment of the 1972 Clean Water Act led to construction or expansion of additional sewage treatment plants in the Potomac watershed. Controls on phosphorus , one of the principal contributors to eutrophication, were implemented in

10282-712: The states again gathered in Philadelphia at the Constitutional Convention , in 1788, where they ratified the United States Constitution , which remains the oldest and longest-standing written and codified national constitution in force in the world. The Mid-Atlantic region was settled during the colonial era between the early 17th century and the conclusion of the American Revolutionary War in 1783 by European Americans of primarily Dutch , German , Swedish , English , and other Western European ethnicities. Religious pluralism and freedoms existed in

10388-456: The volume of freshwater, the tidal range, and the extent of evaporation of the water in the estuary. Drowned river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include

10494-453: The water and atmosphere, these organisms are also intaking all or nearly all of the available oxygen creating a hypoxic environment and unbalanced oxygen cycle . The excess carbon in the form of CO 2 can lead to low pH levels and ocean acidification , which is more harmful for vulnerable coastal regions like estuaries. Eutrophication has been seen to negatively impact many plant communities in estuarine ecosystems . Salt marshes are

10600-624: The water column and in sediment , making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays , harbors , lagoons , inlets , or sounds , although some of these water bodies do not strictly meet

10706-835: The water. The main phytoplankton present are diatoms and dinoflagellates which are abundant in the sediment. A primary source of food for many organisms on estuaries, including bacteria , is detritus from the settlement of the sedimentation. Of the thirty-two largest cities in the world in the early 1990s, twenty-two were located on estuaries. As ecosystems, estuaries are under threat from human activities such as pollution and overfishing . They are also threatened by sewage, coastal settlement, land clearance and much more. Estuaries are affected by events far upstream, and concentrate materials such as pollutants and sediments. Land run-off and industrial, agricultural, and domestic waste enter rivers and are discharged into estuaries. Contaminants can be introduced which do not disintegrate rapidly in

10812-590: The watermen of Virginia's Northern Neck. Being situated in an area rich in American history and American heritage has led to the Potomac being nicknamed "the Nation's River". George Washington , the first President of the United States , was born in, surveyed, and spent most of his life within, the Potomac basin. All of Washington, D.C., the nation's capital city , also lies within the watershed. The First United States Congress by act of July 16, 1790 stated that

10918-421: The western side of South Branch Mountain , 3,028 feet (923 m), the South Branch creates a series of bends and flows to the northeast by Springfield through Blue's Ford. After two additional horseshoe bends (meanders), the South Branch flows under the old Baltimore and Ohio Railroad mainline between Green Spring and South Branch Depot , and joins the North Branch to form the Potomac. This stretch encompasses

11024-621: The western side of Cave Mountain through the 20-mile (32 km) long Smoke Hole Canyon , until its confluence with the North Fork at Cabins , where it flows east to Petersburg . At Petersburg, the South Branch Valley Railroad begins, which parallels the river until its mouth at Green Spring . In its eastern course from Petersburg into Hardy County , the South Branch becomes more navigable allowing for canoes and smaller river vessels. The river splits and forms

11130-476: Was Jennings Randolph Lake on the North Branch. The Corps built a supplementary water intake for the Washington Aqueduct at Little Falls in 1959. In 1940 Congress passed a law authorizing the creation of an interstate compact to coordinate water quality management among states in the Potomac basin. Maryland, West Virginia, Pennsylvania, Virginia, and the District of Columbia agreed to establish

11236-589: Was in March 1936 when it reached 426,000 cubic feet (12,100 m) /s. The lowest average daily flow ever recorded at the same location was 601.0 cubic feet (17.02 m) /s in September 1966 The highest crest of the Potomac ever registered at Little Falls was 28.10 ft, on March 19, 1936; however, the most damaging flood to affect Washington, DC and its metropolitan area was that of October 1942. For 400 years Maryland and Virginia have disputed control of

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