Potomac (river)
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The Potomac River () drains the Mid-Atlantic United States, flowing from the Potomac Highlands into Chesapeake Bay. 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 of 14,700 square miles (38,000 km2), and is the fourth-largest river along the
East Coast of the United States The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the coastline along which the Eastern United States meets the North Atlantic Ocean. The eastern seaboard contains the coa ...
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 and Washington, D.C. on the left descending bank and between 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.


Course

The Potomac River runs from Fairfax Stone Historical Monument State Park 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 Tucker may refer to: Places United States * Tucker, Arkansas * Tucker, Georgia * Tucker, Mississippi * Tucker, Missouri * Tucker, Utah, ghost town * Tucker County, West Virginia Outer space * Tucker (crater), a small lunar impact crater in the s ...
, 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. 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 nort ...
, 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 The Piedmont is a plateau region located in the Eastern United States. It is situated between the Atlantic coastal plain and the main Appalachian Mountains, stretching from New York in the north to central Alabama in the south. The Piedmont ...
, and the
Atlantic coastal plain The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...
. Once the Potomac drops from the Piedmont to the Coastal Plain at the Atlantic Seaboard fall line at Little Falls,
tides Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can ...
further influence the river as it passes through Washington, D.C. and beyond.
Salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
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.


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 October ...
located at the junction of Grant,
Tucker Tucker may refer to: Places United States * Tucker, Arkansas * Tucker, Georgia * Tucker, Mississippi * Tucker, Missouri * Tucker, Utah, ghost town * Tucker County, West Virginia Outer space * Tucker (crater), a small lunar impact crater in the s ...
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 Jennings Randolph Lake is a reservoir of located on the North Branch Potomac River in Garrett County, Maryland and Mineral County, West Virginia. It is approximately eight miles upstream of Bloomington, Maryland, and approximately five miles n ...
, 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 enc ...
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 People *Luke (given name), a masculine given name (including a list of people and characters with the name) *Luke (surname) (including a list of people and characters with the name) *Luke the Evangelist, author of the Gospel of Luke. Also known as ...
, 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 Cumberland ( ) is a historic county in the far North West England. It covers part of the Lake District as well as the north Pennines and Solway Firth coast. Cumberland had an administrative function from the 12th century until 1974. From 19 ...
, 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.


South Branch Potomac River

The exact location of the South Branch's source is northwest of Hightown along
U.S. Route 250 U.S. Route 250 (US 250) is a route of the United States Numbered Highway System, and is a spur of U.S. Route 50. It currently runs for from Richmond, Virginia to Sandusky, Ohio. It passes through the states of Virginia, West Virginia, and Ohio. ...
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 water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a 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 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 Franklin may refer to: People * Franklin (given name) * Franklin (surname) * Franklin (class), a member of a historical English social class Places Australia * Franklin, Tasmania, a township * Division of Franklin, federal electoral d ...
at the junction of U.S. Route 220 and
U.S. Route 33 U.S. Route 33 (US 33) is a United States Numbered Highway that runs northwest–southeast for from northern Indiana to Richmond, Virginia, passing through Ohio and West Virginia en route. Although most odd-numbered U.S. routes are north– ...
. After Franklin, the South Branch continues north through the Monongahela National Forest to
Upper Tract Upper Tract is an unincorporated community in Pendleton County, West Virginia, United States. Description The community lies along U.S. Highway 220 at the confluence of Reeds Creek and the South Branch Potomac River. it has post office with ...
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 Petersburg, or Petersburgh, may refer to: Places Australia *Petersburg, former name of Peterborough, South Australia Canada * Petersburg, Ontario Russia *Saint Petersburg, sometimes referred to as Petersburg United States *Peterborg, U.S. Virg ...
. At Petersburg, the
South Branch Valley Railroad The South Branch Valley Railroad is a railroad in the Eastern Panhandle of West Virginia. The branch line, which parallels the South Branch Potomac River, runs north from Petersburg to Green Spring, where it connects to the national rail netw ...
begins, which parallelsthe river until its mouth at Green Spring. In its eastern course from Petersburg into
Hardy County Hardy County is a county in the U.S. state of West Virginia. As of the 2020 census, the population was 14,299. Its county seat is Moorefield. The county was created from Hampshire County in 1786 and named for Samuel Hardy, a distinguished Vi ...
, 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-resol ...
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 Mill Creek Mountain is a continuous mountain ridge that runs northeast through Hampshire and Hardy counties in the Eastern Panhandle region of the U.S. state of West Virginia. Rising to its greatest elevation of at High Knob, Mill Creek is a fol ...
(2,119 ft) and to its east by Sawmill Ridge (1,644 ft). This area is the habitat to
bald eagles The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...
. 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 A county highway (also county road or county route; usually abbreviated CH or CR) is a road in the United States and in the Canadian province of Ontario that is designated and/or maintained by the county highway department. Route numbering can ...
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 U.S. Route 50 or U.S. Highway 50 (US 50) is a major east–west route of the U.S. Highway system, stretching from Interstate 80 (I-80) in West Sacramento, California, to Maryland Route 528 (MD 528) in Ocean City, Maryland, on the Atlanti ...
) and joined by Sulphur Spring Run where it forms
Valley View Island Valley View Island is an island bar on the South Branch Potomac River near Romney in the U.S. state of West Virginia. The island is formed at the confluence of the South Branch Potomac River with Sulphur Spring Run at the foot of Romney's Yello ...
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 Springfield may refer to: * Springfield (toponym), the place name in general Places and locations Australia * Springfield, New South Wales (Central Coast) * Springfield, New South Wales (Snowy Monaro Regional Council) * Springfield, Queenslan ...
through Blue's Ford. After two additional horseshoe bends (meanders), the South Branch flows under the old
Baltimore and Ohio Railroad The Baltimore and Ohio Railroad was the first common carrier railroad and the oldest railroad in the United States, with its first section opening in 1830. Merchants from Baltimore, which had benefited to some extent from the construction of ...
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 In geography, a confluence (also: ''conflux'') occurs where two or more flowing bodies of water join to form a single channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main stem); o ...
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 Virgini ...
, 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 Joh ...
,
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 Pa ...
,
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 Maryl ...
, Fifteenmile Creek, Sleepy Creek,
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 i ...
, 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 The Shenandoah River is the principal tributary of the Potomac River, long with two forks approximately long each,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 in t ...
, 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, Tenmile Creek, Great Seneca Creek, Old Sugarland Run,
Muddy Branch Muddy Branch is a tributary stream of the Potomac River in Montgomery County, Maryland, United States, located about northwest of Washington, D.C. Course The headwaters of the stream originate in Gaithersburg, and the stream flows southwest f ...
, 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. This 108-mile (174-km) stretch encompasses the Potomac from a short distance below the Washington, DC -
Montgomery County Montgomery County may refer to: Australia * The former name of Montgomery Land District, Tasmania United Kingdom * The historic county of Montgomeryshire, Wales, also called County of Montgomery United States * Montgomery County, Alabama * Mon ...
line, just downstream of the
Little Falls of the Potomac River Little Falls is an area of rapids located where the Potomac River crosses the Atlantic Seaboard fall line where Washington, DC, Maryland and Virginia meet. Descending from the harder and older rocks of the Piedmont Plateau to the softer sediment ...
, to the Chesapeake Bay. Along the way the following tributaries drain into the Potomac:
Pimmit Run Pimmit 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 runs from Fairfax County to the Potomac River at Chain Bridge in the Arling ...
, Gulf Branch,
Donaldson Run Donaldson Run is a stream in Arlington County, Virginia, Arlington County, Virginia. From its source near Marymount University, Donaldson Run flows on a northeastern course and empties into the Potomac River within the federal parklands of the Ge ...
, 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 Siste ...
, Maddox Branch, Foundry Branch,
Rock Creek Rock Creek or Rockcreek may refer to: Streams United States * Rock Creek (California) * Rock Creek (Fountain Creek tributary), Colorado * Rock Creek (Idaho) * Rock Creek (Kankakee River tributary), Illinois * Rock Creek (Wapsipinicon River tribut ...
, Rocky Run, Tiber Creek, Roaches Run, Washington Channel, Anacostia River,
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 pro ...
,
Oxon Creek Oxon Creek is a stream on the Potomac River which feeds a cove that straddles the border between Washington, D.C. and Prince George's County, Maryland just north of Interstate 495 (Capital Beltway) at Woodrow Wilson Bridge. Oxon Creek heads at the ...
,
Hunting Creek Hunting Creek is a cove and tributary stream of the Potomac River between the City of Alexandria and Fairfax County Fairfax County, officially the County of Fairfax, is a County (United States), county in the Commonwealth (U.S. state), Commo ...
, 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, Prince George's County, Marylan ...
, Little Hunting Creek,
Dogue Creek Dogue 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 Fairfax County, Virginia, named for the Tauxenent Indigenous Native ...
,
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 The Potomac River () drains the Mid-Atlantic United States, ...
, Occoquan River,
Neabsco Creek Neabsco Creek is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 tributary of the lower tidal segment of the Potomac River in eastern Prince William County, Virginia. T ...
,
Powell's Creek Powell's Creek is a tributary of the James River on the south side of the James River in Prince George County, Virginia, United States. The creek borders James River National Wildlife Refuge near Garysville, Virginia. History In 1730, a tob ...
,
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 A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful engi ...
,
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 , Creek (tidal), tidal tributary of the Potomac River in Charles County, Maryland, Charles County, Maryland, United States, located between Cedar Point Neck and Tayloe Neck. Its watershed area (excluding water) is , with 2% imp ...
,
Chotank Creek King George County is a county (United States), county located in the Commonwealth of Virginia. As of the 2020 United States Census, 2020 census, the population sits at 26,723. Its county seat is the town of King George, Virginia, King George. ...
,
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 Gambo may refer to: Places * Gambo, Central African Republic, a town in the Central African Republic * Gambo, Newfoundland and Labrador, a town in northeastern Newfoundland, Newfoundland and Labrador, Canada Ships * USS ''West Gambo'' (ID-3220 ...
,
Clifton Creek Clifton Creek is a suburbs and localities (Australia), locality in the Shire of East Gippsland, Victoria (Australia), Victoria, Australia. In the 2016 Australian census, 2016 census, Clifton Creek had a population of 237 people. Clifton Creek Pr ...
, 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 Breton most often refers to: *anything associated with Brittany, and generally **Breton people **Breton language, a Southwestern Brittonic Celtic language of the Indo-European language family, spoken in Brittany **Breton (horse), a breed ** Gale ...
, 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 t ...
,
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. Geolo ...
, 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 Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" *Artel Great (born ...
''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 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 th ...
, 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 In geography, a confluence (also: ''conflux'') occurs where two or more flowing bodies of water join to form a single channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main stem); o ...
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 The Battle of Shepherdstown, also known as the Battle of Boteler's Ford, took place September 19–20, 1862, at Boteler's Ford along the Potomac River, during the Maryland campaign of the American Civil War. After the Battle of Antietam on Se ...
. 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 Nort ...
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 Cumberland ( ) is a historic county in the far North West England. It covers part of the Lake District as well as the north Pennines and Solway Firth coast. Cumberland had an administrative function from the 12th century until 1974. From 19 ...
, 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 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 Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a ''run'' (a smoothly flowing part of a stream) and a ''cascade''. ...
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 with the opening of the Washington Aqueduct in 1864, using a
water intake A water supply network or water supply system is a system of engineered hydrologic and hydraulic components that provide water supply. A water supply system typically includes the following: # A drainage basin (see water purification – source ...
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, 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 The Potomac River basin reservoir projects were U.S. Army Corps of Engineers programs that sought to regulate the flow of the Potomac River to control flooding, to assure a reliable water supply for Washington, D.C., and to provide recreational oppo ...
, 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 of the Potomac. Apart from small-scale dams intended to divert water for municipal use in the District of Columbia and into the Chesapeake an ...
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 Jennings Randolph Lake is a reservoir of located on the North Branch Potomac River in Garrett County, Maryland and Mineral County, West Virginia. It is approximately eight miles upstream of Bloomington, Maryland, and approximately five miles n ...
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 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 and agriculture upstream and urban
sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residenc ...
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 market ...
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 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 mic ...
blooms covering the river's surface, President
Lyndon Johnson Lyndon Baines Johnson (; August 27, 1908January 22, 1973), often referred to by his initials LBJ, was an American politician who served as the 36th president of the United States from 1963 to 1969. He had previously served as the 37th vice ...
declared the river "a national disgrace" and set in motion a long-term effort to reduce pollution from
sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residenc ...
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 The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibiliti ...
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 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 upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as ...
,
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s and other toxic chemicals, over-fishing, alien species, and pathogens associated with
fecal coliform A fecal coliform (British: faecal coliform) is a facultatively anaerobic, rod-shaped, gram-negative, non-sporulating bacterium. Coliform bacteria generally originate in the intestines of warm-blooded animals. Fecal coliforms are capable of growth ...
bacteria and
shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater envir ...
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" 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 The striped bass (''Morone saxatilis''), also called the Atlantic striped bass, striper, linesider, rock, or rockfish, is an anadromous perciform fish of the family Moronidae found primarily along the Atlantic coast of North America. It has al ...
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 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 The Mount Vernon Conference was a meeting of delegates from Virginia and Maryland held March 21–28, 1785, to discuss navigational rights in the states' common waterways. On March 28, 1785, the group drew up a thirteen-point proposal to govern th ...
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 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 court cases, and over state court cases that involve a point o ...
, 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 Secession is the withdrawal of a group from a larger entity, especially a political entity, but also from any organization, union or military alliance. Some of the most famous and significant secessions have been: the former Soviet republics lea ...
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 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 Tucker may refer to: Places United States * Tucker, Arkansas * Tucker, Georgia * Tucker, Mississippi * Tucker, Missouri * Tucker, Utah, ghost town * Tucker County, West Virginia Outer space * Tucker (crater), a small lunar impact crater in the s ...
and
Pendleton Pendleton may refer to: Places ;United Kingdom *Pendleton, Lancashire, England *Pendleton, Greater Manchester, England ;United States *Pendleton, Indiana * Pendleton, Missouri *Pendleton, New York *Pendleton, Oregon *Pendleton, South Carolina *Pe ...
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 Pike, Pikes or The Pike may refer to: Fish * Blue pike or blue walleye, an extinct color morph of the yellow walleye ''Sander vitreus'' * Ctenoluciidae, the "pike characins", some species of which are commonly known as pikes * ''Esox'', genus of ...
, walleye. The northern snakehead, an invasive species resembling the native
bowfin The bowfin (''Amia calva'') is a bony fish, native to North America. Common names include mudfish, mud pike, dogfish, grindle, grinnel, swamp trout, and choupique. It is regarded as a relict, being the sole surviving species of the Halecomorphi ...
, 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 America ...
, 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 The American shad (''Alosa sapidissima'') is a species of anadromous clupeid fish naturally distributed on the North American coast of the North Atlantic, from Newfoundland to Florida, and as an introduced species on the North Pacific coast. The ...
is currently re-bounding as a result of the
ICPRB 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 ...
'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 Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North Ame ...
,
elk The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
, wolves (both gray and red) and
cougar The cougar (''Puma concolor'') is a large Felidae, cat native to the Americas. Its Species distribution, range spans from the Canadian Yukon to the southern Andes in South America and is the most widespread of any large wild terrestrial mamm ...
s 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 Aqueduct Bridge may refer to: * Aqueduct Bridge (Clay City, Indiana), U.S. * Aqueduct Bridge (New York City), now called High Bridge, New York, U.S. * Aqueduct Bridge (Potomac River), between Georgetown, Washington, D.C. and Rosslyn, Virginia, U.S. ...
(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 *
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 This is a list of islands on the Potomac River and its North and South branches. Because the Potomac belongs to Maryland, the majority of its islands lie within that state with some exceptions including portions located in the District of Columbia ...
* List of rivers of Maryland *
List of rivers of Virginia This is a list of rivers in the U.S. state of Virginia. By drainage basin This list is arranged by drainage basin, with respective tributaries, arranged in the order of their confluence from mouth to source, indented under each larger stream's nam ...
* 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 The following have been listed as variant names of the Potomac River throughout its history by the Geographic Names Information System. The Board on Geographic Names The United States Board on Geographic Names (BGN) is a federal body operating u ...
* 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