Potomac River: Wikis


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Potomac River
Country United States
States West Virginia, Maryland, Virginia, Washington D.C.
 - right Shenandoah River
Cities Harper's Ferry, WV, Washington, D.C., Arlington, VA, Alexandria, VA
Source Fairfax Stone
 - elevation 3,060 ft (933 m)
 - coordinates 39°11′43″N 79°29′28″W / 39.19528°N 79.49111°W / 39.19528; -79.49111
Mouth Chesapeake Bay
 - elevation ft (0 m)
 - coordinates 37°59′57″N 76°14′59″W / 37.99917°N 76.24972°W / 37.99917; -76.24972
Length 383 mi (616 km)
Basin 14,700 sq mi (38,073 km2)
Discharge for Washington, D.C.
 - average 10,800 cu ft/s (306 m3/s)
 - max 425,000 cu ft/s (12,035 m3/s)
 - min 600 cu ft/s (17 m3/s)
Discharge elsewhere (average)
 - Point of Rocks, MD 7,320 cu ft/s (207 m3/s)
The Potomac River watershed covers counties in four states and the District of Columbia

The Potomac River (pronounced /pəˈtoʊmək/) flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately 383 statute miles (616 km) long, with a drainage area of about 14,700 square miles (38,000 km²).[1] In terms of area, this makes the Potomac River the fourth largest river along the Atlantic coast of the USA and the 21st largest in the USA. Over 5 million people live within the Potomac watershed, where precipitation provides the equivalent of over 8 m³ (more than 2,100 US gallons) of water per person per year.[citation needed]



The river forms part of the borders between Maryland and Washington, D.C. on the left descending bank and West Virginia and Virginia on the river's right descending bank. The entire lower Potomac River is part of the State of Maryland, with the exception of a small tidal portion within the District of Columbia. 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.

The Potomac River runs 383 miles (616 km) from the Fairfax Stone in West Virginia to Point Lookout, Maryland and drains 14,679 square miles (38,020 km2). The average flow is 10,800 ft³/s (306 m³/s).[1] The largest flow ever recorded on the Potomac at Washington, D.C. was in March 1936 when it reached 425,000 ft³/s (12,000 m³/s).[1] The lowest flow ever recorded at the same location was 600 ft³/s (17 m³/s) in September 1966.[1]

An average of approximately 486 million gallons of water per day (21 m³/s) is withdrawn daily in the Washington area for water supply.[1]

The river has two sources. The source of the North Branch is at the Fairfax Stone located at the junction of Grant, Tucker, Preston counties in West Virginia. The source of 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.

Once the Potomac drops from the Piedmont to the Coastal Plain, 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 the Chesapeake Bay.


View of the Potomac from Mount Vernon

"Potomac" is a European spelling of an Algonquian name for a tribe subject to the Powhatan confederacy, that inhabited the upper reaches of the Northern Neck in the vicinity of Fredericksburg, Virginia. Some accounts say the name means "place where people trade" or "the place to which tribute is brought".[2] The natives called the river above the falls Cohongarooton,[3] translated as "river of geese",[4] and that area was renowned in early years for an abundance of both geese and swans. The spelling of the name has been simplified over the years from "Patawomeke" (as on Captain John Smith's map) to "Patowmack" in the 18th century and now "Potomac". Some scholars have also suggested it is rooted in the ancient Greek for river, "potamos", blended with the Powhatan name "Patawomeke".[citation needed] The river's name was officially decided upon as Potomac by the Board on Geographic Names in 1931.

The Potomac River flowing through water gaps in the Blue Ridge Mountains. Virginia on the left, Maryland on the right, West Virginia in upper right.

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, 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 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. General Robert E. Lee crossed the river, thereby invading the North and threatening Washington, D.C. twice in campaigns climaxing in the battles of Antietam and Gettysburg.

Harpers Ferry, West Virginia at the confluence of the Potomac and Shenandoah rivers

The Patowmack Canal was intended by George Washington to connect the Tidewater near Georgetown with Cumberland, Maryland. Started in 1785, it was not completed until 1802. Financial troubles closed the canal in 1830. The Chesapeake and Ohio Canal operated along the banks of the Potomac in Maryland from 1850 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.

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 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 sewage pollution and restore the beauty and ecology of this historic river. By the end of the 20th century, there was notable success, 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. On November 13, 2007, environmental group the Potomac Conservancy issued the river a grade of "D-plus", citing high levels of pollution and reports of "intersex" fish.[5]

The Potomac was designated as one of the American Heritage Rivers in 1997.

Legal issues

The Potomac near Arlington County, Virginia
Map of land use in the watershed

For 400 years Maryland and Virginia have disputed control of 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 Compact of 1785 and the 1877 Black-Jenkins Award which grants Maryland 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 use of the Potomac. However, in 1996 the MDE denied a permit applied for by the Fairfax County Water Authority to build a water intake valve 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 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.[6]

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 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.[7][8]

Anacostia River, during the 1936 Potomac River flood


As a result of the damaging floods of 1936 and 1937, the Army Corps of Engineers proposed 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, backing its pool up to Great Falls. Just above Great Falls, a much larger dam was proposed whose reservoir would extend to Harpers Ferry.[9][10] Several other dams were proposed on the Potomac and its tributaries. When detailed studies were issued by the Army Corps of Engineers in the 1950s, they met sustained opposition, led by US Supreme Court Chief Justice William O. Douglas, resulting in the plans' abandonment.[11] The only project that did get built was Jennings Randolph Lake on the North Branch.

North Branch Potomac River

The North Branch between Cumberland, Maryland, and Ridgeley, West Virginia, in 2007

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 miles (43 km) to the man-made Jennings Randolph Lake, an impoundment designed for flood control. Below the dam, the North Branch cuts 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. It 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 the Chesapeake Bay.

The following are tributaries of the North Branch Potomac River, listed in order from the source to its mouth.

South Branch Potomac River

Oblique air photo of the confluence of the North and South Branches near Green Spring, West Virginia.

The South Branch Potomac River has its headwaters in northwestern Highland County, Virginia near Hightown along the eastern edge of the Allegheny Front. The mouth of the South Branch lies east of Green Spring in Hampshire County, West Virginia where it meets the North Branch Potomac River to form the Potomac. A topographic map of the confluence of the North and South Branches can be viewed here.

South Branch nomenclature

Early pioneer sources claim that the indigenous Native Americans of the region referred to the South Branch Potomac River as the Wappatomaka. Other variants of this name throughout the river's history were South Branch of Potowmac River, South Branch of the Potowmac River, South Fork Potomac River, Wapacomo River, Wapocomo River, Wappacoma River, Wappatomaka River, and Wappatomica River.

Places settled in the South Branch valley bearing variants of "Wappatomaka" include Wappocomo plantation built in 1774 and the unincorporated hamlet of Wappocomo (sometimes spelled Wapocomo) at Hanging Rocks, both north of Romney on West Virginia Route 28.

South Branch headwaters and course

The exact location of the South Branch's source is northwest of Hightown along Parkersburg Pike (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 Crab Bottom Road through the communities of New Hampden and Crab Bottom. At Forks of Waters, the South Branch joins with Strait Creek and flows north across 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, 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 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 is joined with the South Branch Valley Railroad, which it parallels until its mouth at Green Spring.

Canoers at Hanging Rocks on the South Branch in the 1890s.

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 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 is the habitat to endangered 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 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 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 another horseshoe bend, 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.

South Branch tributaries

North Fork South Branch Potomac River

The North Fork South Branch below Seneca Rocks in Pendleton County, West Virginia

The North Fork South Branch Potomac River forms just north of the Virginia/West Virginia border in Pendleton County at the confluence of the Laurel Fork and Straight Fork along Big Mountain (3,881 ft). From Circleville, the North Fork flows northeast through Pendleton County between the Fore Knobs (2,949 ft) to its west and the River Knobs, 2,490 feet (759 m) to its east. At Seneca Rocks, the North Fork is met by Seneca Creek. From Seneca Rocks, the North Fork continues to flow northeast along the western edge of North Fork Mountain 3,389 feet (1033 m) into Grant County. Flowing east through North Fork Gap, the North Fork joins the South Branch Potomac at the town of Cabins, west of Petersburg.

South Fork South Branch Potomac River

The South Fork South Branch Potomac River forms just north of U.S. Route 250 in Highland County, Virginia near Head Waters and flows 55 miles (89 km) north-northeastward to the South Branch Potomac River at Moorefield in Hardy County, West Virginia. From 1896 to 1929, it was named the Moorefield River by the Board on Geographic Names to avoid confusion with the South Branch.

Upper Potomac River

This stretch encompasses the stretch of the Potomac River from the confluence of the North and South Branches to the Great Falls of the Potomac River at Great Falls, Virginia.

Upper Potomac tributaries

Tidal Potomac River

Jefferson Memorial in Washington, D.C., viewed from across the Tidal Basin of the Potomac.
Rosslyn as seen from Theodore Roosevelt Island in the Potomac river.
The Pentagon, looking northeast with the Potomac in the distance.

The Tidal or Lower Potomac River lies below the fall line. This stretch encompasses the Potomac from about one mile (2 km) below the Washington, DC - Montgomery County, MD line, just below the Little Falls of the Potomac River where the tidal river begins, to the Chesapeake Bay.

Tidal Potomac tributaries

See also


  1. ^ a b c d e "Facts & FAQs". Interstate Commission on the Potomac River Basin, Rockville, MD. 2009-09-16. http://www.potomacriver.org/cms/index.php?option=com_content&view=article&id=70&Itemid=57. Retrieved 2010-02-05. 
  2. ^ cf. Ojibwe: Baadimaag-ziibi, from biidimaw "bring something to somebody" Freelang Ojibwe Dictionary
  3. ^ Legends of Loudoun: An account of the history and homes of a border county of Virginia's Northern Neck, Harrison Williams, p. 26.
  4. ^ cf. Odawa: ikagookaanitoo-ziibi "river that is abundant with geese" Freelang Ojibwe Dictionary
  5. ^ Fahrenthold, David A. (November 13, 2007). "Potomac Recovery Deemed At Risk". The Washington Post. http://www.washingtonpost.com/wp-dyn/content/article/2007/11/12/AR2007111201814.html. Retrieved 2007-11-13. 
  6. ^ U.S. Supreme Court. Virginia v. Maryland, 540 U.S. 56 (2003)
  7. ^ Maryland v. West Virginia, 217 U.S. 1 (1910)
  8. ^ Maryland v. West Virginia, 217 U.S. 577 (1910)
  9. ^ AP (April 24, 1964). "Potomac Water Plan Approved, Dam Included". Fredericksburg Free-Lance Star. http://en.wikipedia.org/w/index.php?title=Potomac_River&action=edit&section=4. Retrieved 2009-11-13. 
  10. ^ Carey, Frank (December 4, 1963). "Potomac Dam Is Opposed By Virginians". Fredericksburg Free-Lance Star. http://news.google.com/newspapers?nid=1298&dat=19631204&id=cuQPAAAAIBAJ&sjid=sYsDAAAAIBAJ&pg=5587,5390295. Retrieved 2009-11-13. 
  11. ^ Joel Achenbach (May 5, 2002). "America's River". Washington Post. pp. W12. http://www.washingtonpost.com/ac2/wp-dyn?pagename=article&node=&contentId=A13425-2002May1. 


  • Smith, J. Lawrence, The Potomac Naturalist: The Natural History of the Headwaters of the Historic Potomac (1968), Parsons, WV: McClain Printing Co.; ISBN 0870120239; ISBN 978-0870120237

External links

Potomac River system
Cities and towns | Bridges | Islands | Tributaries | Variant names
District of Columbia | Maryland | Pennsylvania | Virginia | West Virginia
Streams shown as: Major tributaries • subtributaries • (subsubtributaries) • (subsubsubtributaries)

Simple English

The Potomac River is a river in the eastern United States. It is 665 kilometers long. It forms part of the borders between Maryland, West Virginia, Washington, D.C., and Virginia. The Potomac flows to the Chesapeake Bay. It has two sources. The North Branch starts at Fairfax Stone in West Virginia, and the South Branch starts in Highland County, Virginia. The North Branch and the South Branch meet in Hampshire County, West Virginia, and make the Potomac River.


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