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The Potomac River () drains the Mid-Atlantic
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, flowing from the Potomac Highlands into
Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
. It is long,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data
The National Map
. Retrieved August 15, 2011
with a
drainage area 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. A basin is separated from adjacent basins by a perimeter, ...
of 14,700 square miles (38,000 km2), and is the fourth-largest river along the East Coast of the United States and the 21st-largest in the United States. Over 5 million people live within its
watershed Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, called a "watershe ...
. The river forms part of the borders between
Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean t ...
and Washington, D.C. on the left descending bank and between
West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...
and
Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...
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.


Course

The Potomac River runs from
Fairfax Stone Historical Monument State Park Fairfax Stone Historical Monument State Park is a West Virginia state park commemorating the Fairfax Stone, a surveyor's marker and boundary stone at the source of the North Branch of the Potomac River. The original stone was placed on Octobe ...
in West Virginia on the Allegheny Plateau to Point Lookout, Maryland, and drains . The length of the river from the junction of its North and South Branches to Point Lookout is . 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 Preston is a place name, surname and given name that may refer to: Places England *Preston, Lancashire, an urban settlement **The City of Preston, Lancashire, a borough and non-metropolitan district which contains the settlement **County Boro ...
counties in
West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...
. 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. As it flows from its headwaters down to the Chesapeake Bay, the Potomac traverses five geological provinces: the
Appalachian Plateau The Appalachian Plateau is a series of rugged dissected plateaus located on the western side of the Appalachian Mountains. The Appalachian Mountains are a mountain range that run down the Eastern United States. The Appalachian Plateau is the nor ...
, the
Ridge and Valley The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending ...
, the Blue Ridge, the Piedmont Plateau, and the Atlantic coastal plain. Once the Potomac drops from the
Piedmont it, Piemontese , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographics1_title2 ...
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 An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...
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.


North Branch Potomac River

The source of the North Branch Potomac River is at the
Fairfax Stone Fairfax Stone Historical Monument State Park is a West Virginia state park commemorating the Fairfax Stone, a surveyor's marker and boundary stone at the source of the North Branch of the Potomac River. The original stone was placed on Octobe ...
located at the junction of Grant, Tucker and
Preston Preston is a place name, surname and given name that may refer to: Places England *Preston, Lancashire, an urban settlement **The City of Preston, Lancashire, a borough and non-metropolitan district which contains the settlement **County Boro ...
counties in West Virginia. From the Fairfax Stone, the North Branch Potomac River flows to the man-made Jennings Randolph Lake, an
impoundment Impoundment may refer to: Water control * The result of a dam, creating a body of water ** A reservoir, formed by a dam ** Coal slurry impoundment, a specialized form of such a reservoir used for coal mining and processing * Impounded dock, an en ...
designed for flood control and emergency water supply. 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 Western Port, (Boonwurrung: ''Warn Marin'') commonly but unofficially known as Western Port Bay, is a large tidal bay in southern Victoria, Australia, opening into Bass Strait. It is the second largest bay in the state. Geographically, it is ...
in Maryland and then on by Keyser, West Virginia to Cumberland, Maryland. At Cumberland, the river turns southeast. 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 the
Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
.


South Branch Potomac River

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 A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams ...
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 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 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 parallelsthe 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 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 The South Branch Potomac River has its headwaters in northwestern Highland County, Virginia near Hightown along the eastern edge of the Allegheny Front. After a river distance of ,U.S. Geological Survey. National Hydrography Dataset high-resolu ...
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 bald eagles. The Trough passes into Hampshire County and ends at its confluence with Sawmill Run south of Glebe and
Sector Sector may refer to: Places * Sector, West Virginia, U.S. Geometry * Circular sector, the portion of a disc enclosed by two radii and a circular arc * Hyperbolic sector, a region enclosed by two radii and a hyperbolic arc * Spherical sector, a po ...
. 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 The Northwestern Turnpike is a historic road in West Virginia ( Virginia at the time the road was created), important for being historically one of the major roads crossing the Appalachians, financed by the Virginia Board of Public Works in the 1 ...
( 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 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.


Upper Potomac River

This stretch encompasses 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 The Little Cacapon River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 free-flowing tributary of the Potomac River in the center of Hampshire County, West Virgin ...
, Sideling Hill Creek, Cacapon River,
Sir Johns Run Sir Johns Run is an U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 tributary stream of the Potomac River in Morgan County, West Virginia. For most of its course, Sir John ...
,
Warm Spring Run Warm Spring Run is an U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 non-navigable tributary stream of the Potomac River in Morgan County of West Virginia's Eastern Pan ...
,
Tonoloway Creek Tonoloway Creek, also known as Great Tonoloway Creek, is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 tributary stream of the Potomac River in the U.S. states of Mar ...
, Fifteenmile Creek,
Sleepy Creek Sleepy Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 tributary of the Potomac River in the United States, belonging to the Chesapeake Bay's watershed. The st ...
,
Cherry Run Cherry Run is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 meandering stream that forms the northern section of the boundary between Morgan and Berkeley counties in ...
, Back Creek, Conococheague Creek, and Opequon Creek.


Lower Potomac River

This section covers 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, Catoctin Creek, Tuscarora Creek, Monocacy River,
Little Monocacy River The Little Monocacy River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 tributary stream of the Potomac River. Despite its name, the stream does not feed into the Mo ...
, Broad Run, Goose Creek, Broad Run, Horsepen Branch,
Little Seneca Creek Little Seneca Creek is an U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 stream in Montgomery County, Maryland, roughly northwest of Washington, D.C. Geography The ...
, Tenmile Creek,
Great Seneca Creek Seneca Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 stream in Montgomery County, Maryland, USA, roughly northwest of Washington, D.C. It drains into th ...
, 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.


Tidal Potomac River

The Tidal Potomac River lies below the
Fall Line A fall line (or fall zone) is the area where an upland region and a coastal plain meet and is typically prominent where rivers cross it, with resulting rapids or waterfalls. The uplands are relatively hard crystalline basement rock, and the coa ...
. This 108-mile (174-km) stretch encompasses the Potomac from a short distance below the
Washington, DC ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morg ...
- Montgomery County line, just downstream of the Little Falls of the Potomac River, to the
Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
. Along the way the following tributaries drain into the Potomac: Pimmit Run, Gulf Branch, Donaldson Run, Windy Run,
Spout Run Spout Run is a small stream in Arlington County, Virginia. From its source along Interstate 66, Spout Run flows on a northeastern course paralleling the Spout Run Parkway through a gorge and empties into the Potomac River opposite the Three Sist ...
, Maddox Branch, Foundry Branch, Rock Creek, Rocky Run, Tiber Creek, Roaches Run, Washington Channel,
Anacostia River The Anacostia River is a river in the Mid Atlantic region of the United States. It flows from Prince George's County in Maryland into Washington, D.C., where it joins with the Washington Channel to empty into the Potomac River at Buzzard Poin ...
,
Four Mile Run Four Mile Run is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 stream in Northern Virginia that starts near Interstate 66, at Gordon Avenue in Fairfax County and proc ...
, Oxon Creek,
Hunting Creek Hunting Creek is a cove and tributary stream of the Potomac River between the City of Alexandria and Fairfax County in Virginia. It is formed by Cameron Run flowing from the west. The community of Huntington takes its name from the creek. Jones ...
, Broad Creek, Henson Creek, Swan Creek,
Piscataway Creek Piscataway Creek is an U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 tributary of the Potomac River in Prince George's County, Maryland. The creek is a tidal arm of the ...
, Little Hunting Creek, Dogue Creek,
Accotink Creek Accotink Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 tributary stream of the Potomac River in Fairfax County, Virginia, in the United States. At Springfiel ...
, Pohick Creek,
Pomonkey Creek Pomonkey Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 tidal tributary of the Potomac River, near Bryans Road, Maryland. It is named for the Pamunkey tribe ...
, Occoquan River, Neabsco Creek, Powell's Creek,
Mattawoman Creek Mattawoman Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 coastal-plain tributary to the tidal Potomac River with a mouth at Indian Head, Maryland, downstr ...
, Chicamuxen Creek, Quantico Creek, Little Creek,
Chopawamsic Creek Chopawamsic Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 tributary of the Potomac River in Prince William and Stafford counties, Virginia. Chopawamsic Cree ...
, Tank Creek,
Aquia Creek Aquia Creek () is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 tributary of the tidal segment of the Potomac River and is located in northern Virginia. The creek's h ...
, Potomac Creek,
Nanjemoy Creek Nanjemoy Creek is a , tidal tributary of the Potomac River in Charles County, Maryland, United States, located between Cedar Point Neck and Tayloe Neck. Its watershed area (excluding water) is , with 2% impervious surface in 1994. The Nature Co ...
, Chotank Creek,
Port Tobacco River The Port Tobacco River is a tidal tributary of the Potomac River located in Charles County, Maryland in the United States. The river is approximately in length.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe ...
, Popes Creek, Gambo Creek, Clifton Creek, Piccowaxen Creek, Upper Machodoc Creek, Wicomico River, Cobb Island,
Monroe Creek Monroe or Monroes may refer to: People and fictional characters * Monroe (surname) * Monroe (given name) * James Monroe, 5th President of the United States Places United States * Monroe, Arkansas, an unincorporated community and census-designa ...
,
Mattox Creek Mattox Creek is a tributary of the Potomac River in the Washington District of Westmoreland County, Virginia, near the colonial stagecoach stop of Oak Grove. The creek is long,U.S. Geological Survey. National Hydrography Dataset high-resolution ...
, Popes Creek, Breton Bay, Leonardtown, St. Marys River,
Yeocomico River The Yeocomico River is a tidal tributary of the southern portion of the Potomac River in Virginia's Northern Neck. The Yeocomico forms the boundary between Westmoreland and Northumberland counties. Yeocomico is a Native American name roughly ...
,
Coan River The Coan River is a river in Virginia's Northern Neck region. It is a tributary of the Potomac River The Potomac River () drains the Mid-Atlantic United States, flowing from the Potomac Highlands into Chesapeake Bay. It is long,U.S. Geo ...
, and Hull Creek.


History


Natural history

The river itself 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.


Human history

"Potomac" is a European spelling of '' Patawomeck'', 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 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 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, the watermen of Virginia's Northern Neck. Being situated in an area rich in
American history The history of the lands that became the United States began with the arrival of the first people in the Americas around 15,000 BC. Numerous indigenous cultures formed, and many saw transformations in the 16th century away from more densel ...
and American heritage has led to the Potomac being nicknamed "the Nation's River".
George Washington George Washington (February 22, 1732, 1799) was an American military officer, statesman, and Founding Father who served as the first president of the United States from 1789 to 1797. Appointed by the Continental Congress as commander of ...
, the first
President of the United States The president of the United States (POTUS) is the head of state and head of government of the United States of America. The president directs the Federal government of the United States#Executive branch, executive branch of the Federal gove ...
, was born in, surveyed, and spent most of his life within, the Potomac basin. All of Washington, D.C., the nation's
capital city A capital city or capital is the municipality holding primary status in a country, state, province, department, or other subnational entity, usually as its seat of the government. A capital is typically a city that physically encompasses t ...
, 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 The American Civil War (April 12, 1861 – May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States. It was fought between the Union (American Civil War), Union ("the North") and t ...
in and around the Potomac and its tributaries, such as the 1861
Battle of Ball's Bluff The Battle of Ball's Bluff was an early battle of the American Civil War fought in Loudoun County, Virginia, on October 21, 1861, in which Union Army forces under Major General George B. McClellan suffered a humiliating defeat. The operatio ...
and the 1862 Battle of Shepherdstown. General
Robert E. Lee Robert Edward Lee (January 19, 1807 – October 12, 1870) was a Confederate general during the American Civil War, towards the end of which he was appointed the overall commander of the Confederate States Army. He led the Army of Nor ...
crossed the river, thereby invading the North and threatening Washington, D.C., twice in campaigns climaxing in 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 the Virginia side of the river, it was not completed until 1802. Financial troubles led to the closure of the
canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface f ...
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 the Potomac as its principal source of
drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ...
with the opening of the Washington Aqueduct in 1864, using a water intake constructed at Great Falls.Ways, Harry C. (1996). ''The Washington Aqueduct: 1852-1992.'' (Baltimore, MD: U.S. Army Corps of Engineers, Baltimore District)


Hydrology


Water supply and water quality

An average of approximately of water is withdrawn daily from the Potomac in the Washington area for
water supply Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Th ...
, providing about 78 percent of the region's total water usage, this amount includes approximately 80 percent of 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, the much larger
Seneca Dam Seneca Dam was the last in a series of dams proposed on the Potomac River in the area of the Great Falls (Potomac River), Great Falls of the Potomac. Apart from small-scale dams intended to divert water for municipal use in the District of Columbi ...
was proposed whose reservoir would extend to Harpers Ferry. Several other dams were proposed for the Potomac and its tributaries. 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 was Jennings Randolph Lake on the North Branch. The Corps built a supplementary water intake for the Washington Aqueduct at Little Falls in 1959.Scott, Pamela (2007)
"Capital Engineers: The U.S. Army Corps of Engineers in the Development of Washington, D.C., 1790–2004."
(Washington, DC: U.S. Army Corps of Engineers.) Publication No. EP 870-1-67. p. 256.
In 1940
Congress A congress is a formal meeting of the representatives of different countries, constituent states, organizations, trade unions, political parties, or other groups. The term originated in Late Middle English to denote an encounter (meeting of ...
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 the
Interstate Commission on the Potomac River Basin The 'Interstate Commission on the Potomac River Basin(ICPRB) is an agency composed of commissioners representing the federal government, the states of Maryland, Pennsylvania, Virginia, West Virginia, and the District of Columbia. The ICPRB mission ...
. The compact was amended in 1970 to include coordination of water supply issues and land use issues related to water quality.ICPRB
"Potomac Timeline."
Updated 2008-04-15.
Beginning in the 19th century, with increasing
mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the econom ...
and
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
upstream and urban sewage and
runoff Runoff, run-off or RUNOFF may refer to: * RUNOFF, the first computer text-formatting program * Runoff or run-off, another name for bleed, printing that lies beyond the edges to which a printed sheet is trimmed * Runoff or run-off, a stock marke ...
downstream, the water quality of the Potomac River deteriorated. This created conditions of severe
eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phyt ...
. It is said that President
Abraham Lincoln Abraham Lincoln ( ; February 12, 1809 – April 15, 1865) was an American lawyer, politician, and statesman who served as the 16th president of the United States from 1861 until his assassination in 1865. Lincoln led the nation throu ...
used to escape to the highlands on summer nights to escape the river's stench. In the 1960s, with dense green
algal Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...
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 Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, th ...
from sewage and restore the beauty and ecology of this historic river. One of the significant pollution control projects at the time was the expansion of the
Blue Plains Advanced Wastewater Treatment Plant Blue Plains Advanced Wastewater Treatment Plant, located at 5000 Overlook Ave SW, Washington, DC 20032, is the largest advanced wastewater treatment plant in the world. The facility is operated by the District of Columbia Water and Sewer Author ...
, which serves Washington and several surrounding communities. Enactment of the 1972 Clean Water Act led to construction or expansion of additional
sewage treatment Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding en ...
plants in the Potomac watershed. Controls on
phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
, one of the principal contributors to eutrophication, were implemented in 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 In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
of the Potomac River and its tributaries remain vulnerable to eutrophication, heavy metals, pesticides and other toxic chemicals, over-fishing, alien species, and
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...
s associated with fecal coliform
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
and shellfish diseases. In 2005 two federal agencies, 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 Intersex people are individuals born with any of several sex characteristics including chromosome patterns, gonads, or genitals that, according to the Office of the United Nations High Commissioner for Human Rights, "do not fit typical b ...
" fish. Since then, 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, the catching near
Fletcher's Boat House Fletcher's Cove is a park and recreation area owned and managed by National Park Service, located at 4940 Canal Road, Washington, D.C. 20007, between Chain and Key Bridges, part of Chesapeake and Ohio Canal National Historical Park. Fletcher's ...
of a Striped Bass estimated to weigh 35 lbs was seen as a further indicator of the continuing improvement in the health of the river.


Discharge

The average daily flow during the water years 1931–2018 was  /s. The highest average daily flow ever recorded on the Potomac at Little Falls, Maryland (near Washington, D.C.), was in March 1936 when it reached  /s. The lowest average daily flow ever recorded at the same location was  /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.


Legal issues

For 400 years Maryland and Virginia have disputed control of the Potomac and its North Branch since both states' original
colonial charter A charter is a document that gives colonies the legal rights to exist. Charters can bestow certain rights on a town, city, university, or other institution. Colonial charters were approved when the king gave a grant of exclusive powers for the go ...
s grant the entire river rather than half of it as is normally the case with boundary rivers. In its first state
constitution A constitution is the aggregate of fundamental principles or established precedents that constitute the legal basis of a polity, organisation or other type of entity and commonly determine how that entity is to be governed. When these pr ...
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 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 Fairfax County Water Authority (FCWA or more recently Fairfax Water for short) is the main water company in the Northern Virginia region of the United States, and one of the four major water providers in the Washington, D.C. metropolitan area (the ...
to build 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 The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. Federal tribunals in the United States, federal court cases, and over Stat ...
, 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. 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 In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
and Grant Counties and parts of
Hampshire Hampshire (, ; abbreviated to Hants) is a ceremonial and non-metropolitan county in western South East England on the coast of the English Channel. Home to two major English cities on its south coast, Southampton and Portsmouth, Hampshire ...
,
Hardy Hardy may refer to: People * Hardy (surname) * Hardy (given name) * Hardy (singer), American singer-songwriter Places Antarctica * Mount Hardy, Enderby Land * Hardy Cove, Greenwich Island * Hardy Rocks, Biscoe Islands Australia * Hardy, Sout ...
, 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.


Flora and Fauna


Fish

A variety of fish inhabit the Potomac, including
bass Bass or Basses may refer to: Fish * Bass (fish), various saltwater and freshwater species Music * Bass (sound), describing low-frequency sound or one of several instruments in the bass range: ** Bass (instrument), including: ** Acoustic bass gui ...
, muskellunge, pike, walleye. The northern snakehead, an invasive species resembling the native bowfin, lamprey, and
American eel The American eel (''Anguilla rostrata'') is a facultative catadromous fish found on the eastern coast of North America. Freshwater eels are fish belonging to the elopomorph superorder, a group of phylogenetically ancient teleosts. The Amer ...
, was first seen in 2004. Many types 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 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.


Mammals

Early European colonists who settled along the Potomac found a diversity of large and small mammals living in the dense forests nearby. Bison, elk, wolves (both
gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be compose ...
and red) and cougars were still present at that time, but had been hunted to extirpation by the middle of the 19th century. Among the denizens of the Potomac's banks, beavers and otters met a similar fate, while small populations of American mink and American martens survived into the 20th century in some secluded areas. There is no record of early settlers having observed marine mammals in the Potomac, but several sightings of Atlantic bottle-nosed dolphins (''Tursiops truncatus'') were reported during the 19th century. In July 1844. a pod of 14 adults and young was followed up the river by men in boats as high as the Aqueduct Bridge (approximately the same location occupied by Key Bridge today). Since 2015, perhaps as a result of warmer temperatures, rising water levels in the Chesapeake Bay and improving water quality in the Potomac, unprecedented numbers of Atlantic bottle-nosed dolphins have been observed in the river. According to Dr Janet Mann of Georgetown University'
Potomac-Chesapeake Dolphin Project
more than 500 individual members of the species have been identified in the Potomac during this period.


Birds


Reptiles


Amphibians


Additional images


Upper and lower Potomac


Tidal Potomac

 


Other


See also

* Air Florida Flight 90 *
List of cities and towns along the Potomac River This is a list of cities, towns, and communities along the Potomac River and its branches in the United States. Potomac River Alphabetically * Alexandria, Virginia *Arlington, Virginia * Belle Haven, Virginia * Bolivar, West Virginia * Brookm ...
*
List of crossings of the Potomac River This is a list of bridges and other crossings of the Potomac River and its North and South branches. Within each section, crossings are listed from the source moving downstream. Potomac River This list contains only crossings of the main channel. ...
* List of islands on the Potomac River * List of rivers of Maryland * List of rivers of Virginia * List of rivers of West Virginia *
List of tributaries of the Potomac River This is a complete list of tributary streams of the Potomac River in the Eastern United States, listed in order from source to mouth. *North Branch Potomac River (Maryland/West Virginia) *South Branch Potomac River (Virginia/West Virginia) * Town ...
* List of variant names of the Potomac River * Potomac Heritage Trail


Notes and references


Notes

* * * * * *


References


Works cited

* Rice, James D., ''Nature and History in the Potomac Country: From Hunter-Gatherers to the Age of Jefferson.'' (2009), Baltimore: Johns Hopkins University Press; ; * Smith, J. Lawrence, ''The Potomac Naturalist: The Natural History of the Headwaters of the Historic Potomac'' (1968), Parsons, WV: McClain Printing Co.; ;


External links


Advanced Hydrologic Prediction Service

Baltimore/Washington (Sterling, VA)
- including Potomac River levels ** Potomac River level a
Williamsport
** Potomac River level a
Harpers Ferry
** Potomac River level a
Point of Rocks
** Potomac River level a
Little Falls
** Potomac River level a
Wisconsin Avenue

''Geology of the National Capital Region: Field Trip Guidebook'' (2004) edited by Scott Southworth, William Chapin Burton, Reston, VA: U.S. Geological Survey

''Guide to Spring Wildflowers on the Towpath'' (2010) compiled by the C&O Canal Association Nature Committee

Interstate Commission on the Potomac River Basin (ICPRB)

Potomac Conservancy

Potomac Heritage National Scenic Trail

Potomac Riverkeeper

Potomac Timeline
(focus on water quality) by ICPRB
Potomac Watershed Partnership

Potomac Watershed Roundtable

Prince William Conservation Alliance

Stewards of the Potomac Highlands

South Branch Consortium


also available in ttps://pubs.usgs.gov/bul/1471/report.pdf downloadable pdf format* [https://pubs.usgs.gov/of/1997/0060/report.pdf ''The Seven-Storey River: Geomorphology of the Potomac River Channel Between Blockhouse Point, Maryland, and Georgetown, District of Columbia, With Emphasis on the Gorge Complex Below Great Falls'' (1997) by E-an Zen, Reston, VA: US Geological Survey]
VEGETATION ECOLOGY OF THE POTOMAC GORGE
by the Virginia Department of Conservation and Recreation, Division of Natural Heritage
West Virginia Division of Natural Resources

West Virginia Rivers Coalition


* ttp://www.switchfisher.com/admin/CatchGuides/CG-UPCatchguide.html Wade and Shoreline Fishing the Potomac River for Smallmouth Bass {{Authority control Rivers of Washington, D.C. Rivers of Maryland Rivers of Virginia Rivers of West Virginia Monongahela National Forest History of West Virginia Borders of Maryland Borders of Virginia Borders of West Virginia American Heritage Rivers Tributaries of the Chesapeake Bay