Potomac River

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Potomac River
Great Falls of the Potomac River - NPS.jpg
Potomacwatershedmap.png
The Potomac River watershed covers the District of Columbia and parts of four states
Native namePatawomeck
Location
Country United States
State West Virginia, Maryland, Virginia, District of Columbia
Cities Cumberland, MD, Harpers Ferry, WV, Washington, D.C., Alexandria, VA
Physical characteristics
Source Fairfax Stone
  location Preston County, West Virginia, United States
  coordinates 39°11′43″N79°29′28″W / 39.19528°N 79.49111°W / 39.19528; -79.49111
  elevation3,060 ft (930 m)
Mouth Chesapeake Bay
  location
St. Mary's County, Maryland/Northumberland County, Virginia, United States
  coordinates
37°59′57″N76°14′59″W / 37.99917°N 76.24972°W / 37.99917; -76.24972 Coordinates: 37°59′57″N76°14′59″W / 37.99917°N 76.24972°W / 37.99917; -76.24972
  elevation
0 ft (0 m)
Length405 mi (652 km)
Basin size14,700 sq mi (38,000 km2)
Discharge 
  location Little Falls, near Washington, D.C. (non-tidal; water years: 1931–2018) [2]
  average11,498 cu ft/s (325.6 m3/s) (1931–2018)
  minimum4,017 cu ft/s (113.7 m3/s) (2002)
  maximum23,760 cu ft/s (673 m3/s) (1996)
Discharge 
  location Point of Rocks, Maryland
  average9,504 cu ft/s (269.1 m3/s)
Discharge 
  location Hancock, Maryland
  average4,168 cu ft/s (118.0 m3/s)
Discharge 
  location Paw Paw, West Virginia
  average3,376 cu ft/s (95.6 m3/s)
Basin features
Tributaries 
  left Conococheague Creek, Antietam Creek, Monocacy River, Rock Creek, Anacostia River
  right Cacapon River, Shenandoah River, Goose Creek, Occoquan River, Wicomico River
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Note: Since 1996, the Potomac has been the 'sister river' of the Ara River of Tokyo, Japan [3]

The Potomac River ( /pəˈtmək/ ( Loudspeaker.svg listen )) is found within the Mid-Atlantic region of the United States and flows from the Potomac Highlands into the Chesapeake Bay. The river (main stem and North Branch) is approximately 405 miles (652 km) long, [4] with a drainage area of about 14,700 square miles (38,000 km2). [5] In terms of area, this makes the Potomac River the fourth largest river along the Atlantic coast of the United States and the 21st largest in the United States. Over 5 million people live within the Potomac watershed.

Contents

The river forms part of the borders between Maryland and Washington, D.C., on the left descending bank and West Virginia and Virginia on the river's right descending bank. The majority of the lower Potomac River is part of Maryland. Exceptions include a small tidal portion within the District of Columbia, and the border with Virginia being delineated from "point to point" (thus various bays and shoreline indentations lie in Virginia). 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 in Washington, D.C., with Arlington Memorial Bridge in the foreground and Rosslyn, Arlington, Virginia in the background Potomac River in District of Columbia IMG 4720.JPG
The Potomac River in Washington, D.C., with Arlington Memorial Bridge in the foreground and Rosslyn, Arlington, Virginia in the background

The Potomac River runs 405 miles (652 km) from Fairfax Stone Historical Monument State Park in West Virginia on the Allegheny Plateau to Point Lookout, Maryland, and drains 14,679 square miles (38,020 km2). The length of the river from the junction of its North and South Branches to Point Lookout is 302 miles (486 km). [4] The average daily flow during the water years 1931–2018 was 11,498 cubic feet (325.6 m3) /s. [2] 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 426,000 cubic feet (12,100 m3) /s. [2] The lowest average daily flow ever recorded at the same location was 601.0 cubic feet (17.02 m3) /s in September 1966 [2] The highest crest of the Potomac ever registered at Little Falls was 28.10 ft, on March 19, 1936; [6] [7] however, the most damaging flood to affect Washington, DC and its metropolitan area was that of October 1942. [8]

Map showing the five geological provinces through which the Potomac River flows Physiographic provinces of the Mid-Atlantic region by NPS.png
Map showing the five geological provinces through which the Potomac River flows
Major sub-basins and cities of the Potomac River basin PR sub-basins with tributary names.jpg
Major sub-basins and cities of the Potomac River basin

The river has two sources. The source of the North Branch is at the Fairfax Stone located at the junction of Grant, Tucker, and Preston counties in West Virginia. The source of the South Branch is located near Hightown in northern Highland County, Virginia. The river's two branches converge just east of Green Spring in Hampshire County, West Virginia, to form the Potomac. As it flows from its headwaters down to the Chesapeake Bay, the Potomac traverses five geological provinces: the Appalachian Plateau, the Ridge and Valley, the Blue Ridge, the Piedmont Plateau, and the Atlantic coastal plain.

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

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History

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". Detail of 1608 Smith Map showing the Patawomeck River.jpg
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".

"Potomac" is a European spelling of Patawomeck , the Algonquian name of a Native American village on its southern bank. [11] Native Americans had different names for different parts of the river, calling the river above Great Falls Cohongarooton, meaning "honking geese" [12] [13] and "Patawomke" below the Falls, meaning "river of swans". [14] 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". [13] The river's name was officially decided upon as "Potomac" by the Board on Geographic Names in 1931. [15]

Tundra swans were the predominant species of swan on the Potomac River when the Algonquian tribes dwelled along its shores, and continue to be the most populous variety today. Tundra swans (6565983429).jpg
Tundra swans were the predominant species of swan on the Potomac River when the Algonquian tribes dwelled along its shores, and continue to be the most populous variety today.

The river itself is at least 3.5 million years old, [9] likely extending back ten to twenty million years before 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. [17]

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.

View of the Potomac River from George Washington's birthplace in Westmoreland County, Virginia View of the Potomac River - George Washington Birthplace National Monument - Stierch - B.jpg
View of the Potomac River from George Washington's birthplace in Westmoreland County, Virginia
Sunset over the Potomac near Mount Vernon Sunset over the Potomac River 22 Jan 2019.jpg
Sunset over the Potomac near Mount Vernon
Civil War Era
Conferderate army crossing the Potomac River during the invasion of Maryland.jpg
Confederate troops crossing the fords of the Potomac in early September 1862 for the invasion of Maryland, which would culminate in the Battle of Antietam. (Print of a wood carving based on a drawing by Thomas Nast; first published in the September 27, 1862 edition of Harper's Weekly.)
 
Defense of Washington - 6 views- 2 views of Chain Bridge, Pimmitt Run Bridge (small bridge near Chain Bridge), Block House for defense of Aqueduct Bridge, and Georgetown Ferry LCCN2003670507.jpg
Union defenses along the Potomac near Washington, DC
Top row: Chain Bridge (two views) and Pimmit Run Bridge; Bottom Row: Aqueduct Bridget {two views) and Georgetown Ferry
 
PR Chain Bridge Lower Battery ca 1862 LOC.jpg
Union soldiers manning the Lower Battery at the north end of Chain Bridge in 1862.
Being situated in an area rich in American history and American heritage has led to the Potomac being nicknamed "the Nation's River." George Washington, the first President of the United States, was born in, surveyed, and spent most of his life within, the Potomac basin. All of Washington, D.C., the nation's capital city, also lies within the watershed. The 1859 siege of Harper's Ferry at the river's confluence with the Shenandoah was a precursor to numerous epic battles of the American Civil War in and around the Potomac and its tributaries, such as the 1861 Battle of Ball's Bluff and the 1862 Battle of Shepherdstown.
Map of the Potomac River and its environs circa 1862 by Robert Knox Sneden. Map of the Potomac River ~1862 by Sneden LOC.jpg
Map of the Potomac River and its environs circa 1862 by Robert Knox Sneden.
General Robert E. Lee crossed the river, thereby invading the North and threatening Washington, D.C., twice in campaigns climaxing in the battles of Antietam (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. [18]

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 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. [19] 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 with the opening of the Washington Aqueduct in 1864, using a water intake constructed at Great Falls. [20] [21]

Water supply and water quality

An average of approximately 486 million US gallons (1,840,000 m3) 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. [5] [22]

The Potomac River surges over the deck of Chain Bridge during the historic 1936 flood. The bridge was so severely damaged by the raging water, and the debris it carried, that its superstructure had to be re-built; the new bridge was opened to traffic in 1939. (This photograph was taken from a vantage point on Glebe Road in Arlington County, Virginia. The houses on the bluffs in the background are located on the Potomac Palisades of Washington, DC.) The Potomac River surges over Chain Bridge during 1936 Flood 19 March 1936.jpg
The Potomac River surges over the deck of Chain Bridge during the historic 1936 flood. The bridge was so severely damaged by the raging water, and the debris it carried, that its superstructure had to be re-built; the new bridge was opened to traffic in 1939. (This photograph was taken from a vantage point on Glebe Road in Arlington County, Virginia. The houses on the bluffs in the background are located on the Potomac Palisades of Washington, DC.)

As a result of damaging floods in 1936 and 1937, [7] 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 was proposed whose reservoir would extend to Harpers Ferry. [23] 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. [27] The only dam project that did get built was Jennings Randolph Lake on the North Branch. [28] The Corps built a supplementary water intake for the Washington Aqueduct at Little Falls in 1959. [29]

This chart displays the Annual Mean Discharge of the Potomac River measured at Little Falls, Maryland for Water Years 1931-2017 (in cubic feet per second). Source of data: USGS Potomac River Discharge at Little Falls 1931-2017.jpg
This chart displays the Annual Mean Discharge of the Potomac River measured at Little Falls, Maryland for Water Years 1931–2017 (in cubic feet per second). Source of data: USGS
Source of data: USGS PR AMD of Pot Riv min max latest.jpg
Source of data: USGS

In 1940 Congress passed a law authorizing 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 compact was amended in 1970 to include coordination of water supply issues and land use issues related to water quality. [31]

Eutrophication in the Potomac River is evident from this bright green water in Washington, D.C., caused by a dense bloom of cyanobacteria, April 2012 Potomac green water.JPG
Eutrophication in the Potomac River is evident from this bright green water in Washington, D.C., caused by a dense bloom of cyanobacteria, April 2012

Beginning in the 19th century, with increasing mining and agriculture upstream and urban sewage and runoff downstream, the water quality of the Potomac River deteriorated. This created conditions of severe eutrophication. It is said that President Abraham Lincoln used to escape to the highlands on summer nights to escape the river's stench. In the 1960s, with dense green algal blooms covering the river's surface, President Lyndon Johnson declared the river "a national disgrace" and set in motion a long-term effort to reduce pollution from sewage and restore the beauty and ecology of this historic river. One of significant pollution control projects at the time was the expansion of the Blue Plains Advanced Wastewater Treatment Plant, which serves Washington and several surrounding communities. [32] Enactment of the 1972 Clean Water Act led to construction or expansion of additional sewage treatment plants in the Potomac watershed. Controls on phosphorus, one of the principal contributors to eutrophication, were implemented in the 1980s, through sewage plant upgrades and restrictions on phosphorus in detergents. [31]

Monthly Mean Data for Water Years 1930 - 2018
Source of data: USGS PR STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1930 - 2018, BY WATER YEAR.jpg
Monthly Mean Data for Water Years 1930 - 2018
Source of data: USGS

By the end of the 20th century, notable success had been achieved, as massive algal blooms vanished and recreational fishing and boating rebounded. Still, the aquatic habitat of the Potomac River and its tributaries remain vulnerable to eutrophication, heavy metals, pesticides and other toxic chemicals, over-fishing, alien species, and pathogens associated with fecal coliform bacteria and shellfish diseases. In 2005 two federal agencies, 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. [34]

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. [35] 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. [36] 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; [37] in that same month, the catching near Fletcher's Boat House 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. [38]

Top Ten Historic Crests of the Potomac River, 1877–2017
Kitzmiller Hancock Williamsport Shepherdstown
Harpers Ferry Point of Rocks Little Falls Georgetown
Source: National Weather Service
Confluence of the Potomac and Shenandoah at Harpers Ferry - aer photo by NPS.jpg
This westward-looking aerial photograph shows the Shenandoah River (left) flowing into the Potomac River (right) at Harpers Ferry, WV. The Potomac then continues eastward toward the Chesapeake Bay. (Visible in the foreground are the ruins of the famed B&O Bridge which was destroyed nine times during the Civil War -- four times by military action and five times by floods.)
 
PR VA MD WV Boundary near Harpers Ferry by USFWS ebm.png
Boundary between Maryland, Virginia, and West Virginia at Harpers Ferry
 
Potomac River passing through two water gaps.jpg
Satellite view of the Potomac River passing through two water gaps downstream of Harpers Ferry

For 400 years Maryland and Virginia have disputed control of the Potomac and its North Branch, since both states' original colonial charters grant the entire river rather than half of it as is normally the case with boundary rivers. In its first state constitution adopted in 1776, Virginia ceded its claim to the entire river but reserved free use of it, an act disputed by Maryland. Both states acceded to the 1765 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 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, 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. [39]

Map of land use in the watershed Land Use in the Potomac Basin.gif
Map of land use in the watershed

The original charters are silent as to which branch from the upper Potomac serves as the boundary, but this was settled by the 1785 Compact. When West Virginia seceded from Virginia in 1863, the question of West Virginia's succession in title to the lands between the branches of the river was raised, as well as title to the river itself. Claims by Maryland to West Virginia land north of the South Branch (all of Mineral and Grant Counties and parts of Hampshire, Hardy, Tucker and Pendleton Counties) and by West Virginia to the Potomac's high-water mark were rejected by the Supreme Court in two separate decisions in 1910. [40] [41]

Flora of the Potomac River Basin


Fauna of the Potomac River and its Basin

Fish

After an absence lasting many decades, the American Shad has recently returned to the Potomac. American Shad by Duane Raver USFWS.jpg
After an absence lasting many decades, the American Shad has recently returned to the Potomac.

A variety of fish inhabit the Potomac, including bass, muskellunge, pike, walleye. The northern snakehead, an invasive species resembling the native bowfin, lamprey, and American eel, was first seen in 2004. [42] [43] Many types of sunfish are also present in the Potomac and its headwaters. [44] Although rare, bull sharks can be found. [45]

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 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. [46]

Mammals

Several hundred Bottle-nosed Dolphins live six months of the year (from mid-April through mid-October) in the Potomac. Depicted here, a mother with her young. Bottlenose dolphin with young.JPG
Several hundred Bottle-nosed Dolphins live six months of the year (from mid-April through mid-October) in the Potomac. Depicted here, a mother with her young.

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 ( gray and red) and panthers (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 minks and 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). [47]

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's Potomac-Chesapeake Dolphin Project, more than 500 individual members of the species have been identified in the Potomac during this period. [48]

Birds

A Great Blue Heron Great Blue Heron-27527-2.jpg
A Great Blue Heron
Birds of the Potomac River Basin


Reptiles

Eastern Box Turtles are frequently spotted along the towpath of the C&O Canal. Eastern Box Turtle NPS.jpg
Eastern Box Turtles are frequently spotted along the towpath of the C&O Canal.
Five-lined skink, juvenile Fivelined skink.jpg
Five-lined skink, juvenile

Amphibians

Eastern Tiger Salamanders (Ambystoma tigrinum) can be found sheltering under rocks along the banks of the Potomac. Eastern Tiger Salamander (Ambystoma tigrinum) (25522389762).jpg
Eastern Tiger Salamanders (Ambystoma tigrinum) can be found sheltering under rocks along the banks of the Potomac.

The Potomac River System

North Branch Potomac River

The North Branch between Cumberland, Maryland, and Ridgeley, West Virginia, in 2007 North Branch Potomac River Cumberland.jpg
The North Branch between Cumberland, Maryland, and Ridgeley, West Virginia, in 2007

The source of the North Branch Potomac River is at the Fairfax Stone located at the junction of Grant, Tucker and Preston counties in West Virginia.

Confluence of the North and South Branches of the Potomac River near Potomac Forks Campsite (southeast of Cumberland), Allegany County, Maryland PR confluence of N n S Branches.jpg
Confluence of the North and South Branches of the Potomac River near Potomac Forks Campsite (southeast of Cumberland), Allegany County, Maryland

From the Fairfax Stone, the North Branch Potomac River flows 27 miles (43 km) to the man-made Jennings Randolph Lake, an impoundment designed for flood control 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 in Maryland and then on by Keyser, West Virginia to Cumberland, Maryland. At Cumberland, the river turns southeast. 103 miles (166 km) downstream from its source, [4] 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 following table shows the major tributaries of the North Branch Potomac River, listed in order from the source to its mouth. Numerous other tributary creeks exist.

South Branch Potomac River

The South Branch near South Branch Depot, West Virginia South Branch Potomac River South Branch Depot WV 2004.JPG
The South Branch near South Branch Depot, West Virginia
Oblique air photo of the confluence of the North and South Branches near Green Spring, West Virginia. Facing southwest. River Mountain is on the right, and Town Hill is on the left. Potomac North Branch South Branch confluence air.jpg
Oblique air photo of the confluence of the North and South Branches near Green Spring, West Virginia. Facing southwest. River Mountain is on the right, and Town Hill is on the left.

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 139 miles (224 km), [4] the mouth of the South Branch lies east of Green Spring in Hampshire County, West Virginia where it meets the North Branch Potomac River to form the Potomac. [49]

South Branch nomenclature

The Native Americans of the region, and thus the earliest white settlers, referred to the South Branch Potomac River as the Wappatomaka. Variants throughout the river's history included Wappatomica River, Wapacomo River, Wapocomo River, Wappacoma River, Wappatomaka River, South Branch of Potowmac River, and South Fork Potomac River. [50]

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

South Branch headwaters and course

The exact location of the South Branch's source is northwest of Hightown along U.S. Route 250 on the eastern side of Lantz Mountain (3,934 ft) in Highland County. From Hightown, the South Branch is a small meandering stream that flows northeast along Blue Grass Valley Road through the communities of New Hampden and Blue Grass. At Forks of Waters, the South Branch joins with Strait Creek and flows north across the Virginia/West Virginia border into Pendleton County. The river then travels on a northeastern course along the western side of Jack Mountain (4,045 ft), followed by Sandy Ridge (2,297 ft) along U.S. Route 220. North of the confluence of the South Branch with Smith Creek, the river flows along Town Mountain (2,848 ft) around Franklin at the junction of U.S. Route 220 and U.S. Route 33. After Franklin, the South Branch continues north through the Monongahela National Forest to Upper Tract where it joins with three sizeable streams: Reeds Creek, Mill Run, and Deer Run. Between Big Mountain (2,582 ft) and Cave Mountain (2,821 ft), the South Branch bends around the Eagle Rock (1,483 ft) outcrop and continues its flow northward into Grant County. Into Grant, the South Branch follows the western side of Cave Mountain through the 20-mile (32 km) long Smoke Hole Canyon, until its confluence with the North Fork at Cabins, where it flows east to Petersburg. At Petersburg, the South Branch is joined with the South Branch Valley Railroad, which it parallels until its mouth at Green Spring.

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

In its eastern course from Petersburg into Hardy County, the South Branch becomes more navigable allowing for canoes and smaller river vessels. The river splits and forms a series of large islands while it heads northeast to Moorefield. At Moorefield, the South Branch is joined by the South Fork South Branch Potomac River and runs north to Old Fields where it is fed by Anderson Run and Stony Run. At McNeill, the South Branch flows into the Trough where it is bound to its west by Mill Creek Mountain (2,119 ft) and to its east by Sawmill Ridge (1,644 ft). This area is the habitat to bald eagles. The Trough passes into Hampshire County and ends at its confluence with Sawmill Run south of Glebe and Sector. The South Branch continues north parallel to South Branch River Road (County Route 8) toward Romney with a number of historic plantation farms adjoining it. En route to Romney, the river is fed by Buffalo Run, Mill Run, McDowell Run, and Mill Creek at Vanderlip. The South Branch is traversed by the Northwestern Turnpike (U.S. Route 50) and joined by Sulphur Spring Run where it forms Valley View Island to the west of town. Flowing north of Romney, the river still follows the eastern side of Mill Creek Mountain until it creates a horseshoe bend at Wappocomo's Hanging Rocks around the George W. Washington plantation, Ridgedale. To the west of Three Churches on the western side of South Branch Mountain, 3,028 feet (923 m), the South Branch creates a series of bends and flows to the northeast by Springfield through Blue's Ford. After 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.

North Fork South Branch Potomac River

The North Fork South Branch below Seneca Rocks in Pendleton County, West Virginia North Fork South Branch Potomac River.jpg
The North Fork South Branch below Seneca Rocks in Pendleton County, West Virginia

The North Fork South Branch Potomac River, 43.6 miles (70.2 km) long, [4] forms just north of the Virginia/West Virginia border in Pendleton County at the confluence of the Laurel Fork and Straight Fork along Big Mountain 3,881 feet (1,183 m). From Circleville, the North Fork flows northeast through Pendleton County between the Fore Knobs 2,949 feet (899 m) to its west and the River Knobs, 2,490 feet (759 m) to its east. At Seneca Rocks, the North Fork is met by Seneca Creek. From Seneca Rocks, the North Fork continues to flow northeast along the western edge of North Fork Mountain 3,389 feet (1033 m) into Grant County. Flowing east through North Fork Gap, the North Fork joins the South Branch Potomac at the town of Cabins, west of Petersburg.

South Fork South Branch Potomac River

The South Fork South Branch Potomac River forms just north of U.S. Route 250 in Highland County, Virginia near Monterey, and flows 68.4 miles (110.1 km) [4] north-northeastward to the South Branch Potomac River at Moorefield in Hardy County, West Virginia. From 1896 to 1929, it was named the Moorefield River by the Board on Geographic Names to avoid confusion with the South Branch.

Upper Potomac River

This stretch encompasses the section of the Potomac River from the confluence of its North and South Branches through Opequon Creek near Shepherdstown, West Virginia. [51]

Lower Potomac River

Sunrise view from Jefferson Rock at Harpers Ferry, WV. (In the distance is the Sandy Hook Bridge over the Potomac River that connects Maryland (left bank) with Virginia along U.S. Highway 340.) Sunrise View from Jefferson Rock.jpg
Sunrise view from Jefferson Rock at Harpers Ferry, WV. (In the distance is the Sandy Hook Bridge over the Potomac River that connects Maryland (left bank) with Virginia along U.S. Highway 340.)

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.

Tidal Potomac River

View southwest across the tidal Potomac River from the south end of Cobb Island Road on Cobb Island, Charles County, Maryland 2016-08-28 10 15 51 View southwest across the Potomac River from the south end of Cobb Island Road on Cobb Island, Charles County, Maryland.jpg
View southwest across the tidal Potomac River from the south end of Cobb Island Road on Cobb Island, Charles County, Maryland

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 line, just downstream of the Little Falls of the Potomac River, to the Chesapeake Bay. [52]


 

Additional images

See also

Notes and references

Notes

  • ^  AQU: The diversion dam at Great Falls, often called the "Aqueduct Dam", was built in the 1850s by the US Army Corps of Engineers as part of the project assigned to them by Congress to supply clean water from above Great Falls to Washington, DC. Water diverted by the dam flows 12 miles through a 9-foot diameter pipeline to Dalecarlia Reservoir on the outskirts of the city where it is first allowed to settle and then filtered and purified before being distributed to consumers. Since 1927, potable water from Dalecarlia has also been provided to Arlington County and some other sections of nearby northern Virginia through three 20-inch diameter pipelines that cross the Potomac under the deck of Chain Bridge. In addition, there is nearby a 4-foot diameter conduit constructed in 1967 that traverses the Potomac beneath the riverbed which is used primarily for backup purposes. [53] [54]
  • ^  GHL: "Evidence of the ancient Potomac River bed can be seen in well-rounded boulders, smoothed surfaces and grooves, and beautifully formed potholes. Look for sandstone boulders along the trail, which were deposited by massive floods. The sandy soils along the river trail, with shells mixed in, are a result of sediment deposits from floods. Some of the oldest sediment deposits in the area can be found on Glade Hill, between the Matildaville and Carriage Road trails. Glade Hill was once an island in the Potomac River, and the deposits found there were left before Mather Gorge formed." [55]
  • ^  PIF: "In the Late Pennsylvanian, the rocks of the Stubblefield Falls domain of the Mather Gorge Formation moved up relative to the Sykesville Formation on the steep, west-dipping Plummers Island fault and mylonite zones (Schoenborn, 2001) within an existing Plummers Island shear zone (figs. 5, 6). Shearing formed S2 cleavage with below-closure muscovite growth and more pervasive S2 cleavage in the Sykesville Formation. By the earliest Permian, all of the rocks in the Potomac terrane had cooled through 235°C (figs. 3, 5). Apatite fission-track data indicate cooling through ~90°C to 100°C in Early Jurassic to Early Cretaceous time, with increasing ages to the east, suggesting kilometer-scale rotation of the Potomac terrane in the Cretaceous and (or) Tertiary, with the west side up." [56]
  • ^  BLK: "Two samples collected from the terrace dissected by Great Falls indicate that the Falls were established in their current location by 30 ky. A series of 6 samples taken from a vertical transect just below the falls, indicates that vertical incision continued a rate of 0.5 m/ky between 27 and 12 ky, increasing to nearly 1.0 m/ky during the Holocene. These data suggest that the drop over Great Falls is growing with time. A dramatic increase in outcrop weathering and soil depth 3.5 km downstream of the Falls, suggests that prior to establishment of the Great Falls knickzone, a similar feature was likely present near Black Pond. 10-Be data are not yet available for this paleo knick zone; however, a 10-Be model age >200 ky from the top of Plummers island 5 km down stream of Black Pond suggests a much older period of retreat led to the formation of the Black Pond paleo knick zone." [57]
  • ^  PES: "The Potomac Estuary: From the Chain Bridge in Washington, DC, to Point Lookout at the confluence with the Chesapeake Bay, the Potomac Estuary is a long and narrow estuary—approximately 189 km. With its many tributaries and bays, however, the Potomac Estuary has a shoreline of 1,800 km. The Estuary meanders in a south, southeasterly direction, except for a sharp bend about halfway downriver. The Estuary has three well-defined and distinct zones. The upper zone, from Chain Bridge to Indian Head, is the tidal freshwater reach, with salinities of less than 0.5 parts per thousand (ppt). The middle reach, between Indian Head and the Route 301 Bridge at Morgantown, is the transition zone. The salinity of this zone varies from 0.5 to 7.0 ppt and is often referred to as the zone of maximum turbidity. The lower zone, from the 301 Bridge to Point Lookout, has salinities ranging from 7 to 16 ppt." [58]
  • ^  TRI: The rocky western (upriver) and central portions of the island are part of the Piedmont Plateau, while the southeastern part is within the Atlantic Coastal Plain. At one point opposite Georgetown, the Atlantic Seaboard fall line between the Piedmont and the Coastal Plain can be seen as a natural phenomenon. The island has about 2.5-mile (4.0 km) of shoreline, and the highest area of the island (where the Mason mansion stood) is about 44 feet (13 m) above sea level.

Related Research Articles

Chesapeake Bay An estuary in the U.S. states of Maryland and Virginia

The Chesapeake Bay is an estuary in the U.S. states of Maryland and Virginia. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula with its mouth of the Bay at the south end located between Cape Henry and Cape Charles. With its northern portion in Maryland and the southern part in Virginia, the Chesapeake Bay is a very important feature for the ecology and economy of those two states, as well as others surrounding within its watershed. More than 150 major rivers and streams flow into the Bay's 64,299-square-mile (166,534 km2) drainage basin, which covers parts of six states and all of Washington, D.C. / District of Columbia.

Susquehanna River River in the northeastern United States

The Susquehanna River is a major river located in the northeastern and mid-Atlantic United States. At 444 miles (715 km) long, it is the longest river on the East Coast of the United States. It drains into the Chesapeake Bay. With its watershed, it is the 16th-largest river in the United States, and the longest river in the early 21st-century continental United States without commercial boat traffic.

Patuxent River river in the state of Maryland, United States

The Patuxent River is a tributary of the Chesapeake Bay in the state of Maryland. There are three main river drainages for central Maryland: the Potomac River to the west passing through Washington, D.C., the Patapsco River to the northeast passing through Baltimore, and the Patuxent River between the two. The 908-square-mile (2,352 km2) Patuxent watershed had a rapidly growing population of 590,769 in 2000. It is the largest and longest river entirely within Maryland, and its watershed is the largest completely within the state.

Shenandoah River river in Virginia and West Virginia, United States

The Shenandoah River is a tributary of the Potomac River, 55.6 miles (89.5 km) long with two forks approximately 100 miles (160 km) long each, in the U.S. states of Virginia and West Virginia. The principal tributary of the Potomac, the river and its tributaries drain the central and lower Shenandoah Valley and the Page Valley in the Appalachians on the west side of the Blue Ridge Mountains, in northwestern Virginia and the Eastern Panhandle of West Virginia.

Feather River river in the United States of America

The Feather River is the principal tributary of the Sacramento River, in the Sacramento Valley of Northern California. The river's main stem is about 73 miles (117 km) long. Its length to its most distant headwater tributary is just over 210 miles (340 km). The main stem Feather River begins in Lake Oroville, where its four long tributary forks join together—the South Fork, Middle Fork, North Fork, and West Branch Feather Rivers. These and other tributaries drain part of the northern Sierra Nevada, and the extreme southern Cascades, as well as a small portion of the Sacramento Valley. The total drainage basin is about 6,200 square miles (16,000 km2), with approximately 3,604 square miles (9,330 km2) above Lake Oroville.

Eel River (California) River in northern California, United States

The Eel River is a major river, about 196 miles (315 km) long, of northwestern California. The river and its tributaries form the third largest watershed entirely in California, draining a rugged area of 3,684 square miles (9,540 km2) in five counties. The river flows generally northward through the Coast Ranges west of the Sacramento Valley, emptying into the Pacific Ocean about 10 miles (16 km) downstream from Fortuna and just south of Humboldt Bay. The river provides groundwater recharge, recreation, and industrial, agricultural and municipal water supply.

Patapsco River river in Maryland, United States

The Patapsco River mainstem is a 39-mile-long (63 km) river in central Maryland which flows into the Chesapeake Bay. The river's tidal portion forms the harbor for the city of Baltimore. With its South Branch, the Patapsco forms the northern border of Howard County, Maryland. The name "Patapsco" is derived from the Algonquian pota-psk-ut, which translates to "backwater" or "tide covered with froth."

Chesapeake and Ohio Canal National Historical Park National Historical Park located in the District of Columbia and the states of Maryland and West Virginia

The Chesapeake and Ohio Canal National Historical Park is located in the District of Columbia and the state of Maryland. The park was established in 1961 as a National Monument by President Dwight D. Eisenhower to preserve the neglected remains of the Chesapeake and Ohio Canal and many of its original structures. The canal and towpath trail extends along the Potomac River from Georgetown, Washington, D.C., to Cumberland, Maryland, a distance of 184.5 miles (296.9 km). In 2013, the path was designated as the first section of U.S. Bicycle Route 50.

Rock Creek (Potomac River tributary) tributary of the Potomac River in Maryland and Washington, D.C., United States

Rock Creek is a free-flowing tributary of the Potomac River that empties into the Atlantic Ocean via the Chesapeake Bay. The 32.6-mile (52.5 km) creek drains about 76.5 square miles (198 km2). Its final quarter-mile is affected by tides.

James River and Kanawha Canal United States historic place

The James River and Kanawha Canal was a partially built canal in Virginia intended to facilitate shipments of passengers and freight by water between the western counties of Virginia and the coast. Ultimately its towpath became the roadbed for a rail line following the same course.

Jennings Randolph Lake reservoir spanning the border between Maryland and West Virginia, United States

Jennings Randolph Lake is a reservoir of 952 acres (3.85 km2) 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 north of Elk Garden, West Virginia.

Sleepy Creek river in the United States of America

Sleepy Creek is a 44.0-mile-long (70.8 km) tributary of the Potomac River in the United States, belonging to the Chesapeake Bay's watershed. The stream rises in Frederick County, Virginia, and flows through Morgan County, West Virginia before joining the Potomac near the community of Sleepy Creek.

Great Falls (Potomac River) Waterfalls on the Potomac River in Maryland and Virginia

Great Falls is a series of rapids and waterfalls on the Potomac River, 14 miles (23 km) upstream from Washington, D.C., on the border of Montgomery County, Maryland and Fairfax County, Virginia. Great Falls Park, operated by the National Park Service, is located on the southern banks in Virginia, while Chesapeake and Ohio Canal parkland is located along the northern banks of the river in Maryland. The Potomac and the falls themselves are legally entirely within Maryland, with the state and county boundaries following the south bank of the river.

Goose Creek (Potomac River tributary) tributary of the Potomac River in Virginia, United States

Goose Creek is a 53.9-mile-long (86.7 km) tributary of the Potomac River in Fauquier and Loudoun counties in northern Virginia. It comprises the principal drainage system for the Loudoun Valley.

Great Indian Warpath Part of network of trails in eastern North America used by Native Americans

The Great Indian Warpath (GIW)—also known as the Great Indian War and Trading Path, or the Seneca Trail—was that part of the network of trails in eastern North America developed and used by Native Americans which ran through the Great Appalachian Valley. The system of footpaths extended from what is now upper New York to deep within Alabama. Various Indians traded and made war along the trails, including the Catawba, numerous Algonquian tribes, the Cherokee, and the Iroquois Confederacy. The British traders' name for the route was derived from combining its name among the northeastern Algonquian tribes, Mishimayagat or "Great Trail", with that of the Shawnee and Delaware, Athawominee or "Path where they go armed".

Little Falls Branch (Potomac River tributary) river in the United States of America

Little Falls Branch, a 3.8-mile-long (6.1 km) tributary stream of the Potomac River, is located in Montgomery County, Maryland. In the 19th century, the stream was also called Powder Mill Branch. It drains portions of Bethesda, Somerset, Friendship Heights, and the District of Columbia, flows under the Chesapeake and Ohio Canal (C&O), and empties into the Potomac at Little Falls rapids, which marks the upper end of the tidal Potomac.

Paint Branch one of two headwaters of the Northeast Branch Anacostia River in Montgomery and Prince George’s counties, Maryland, U.S.

Paint Branch is a 14.0-mile-long (22.5 km) stream that flows through Montgomery County and Prince George's County, Maryland. It is a tributary of the Northeast Branch, which flows to the Anacostia River, Potomac River and the Chesapeake Bay.

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 is to enhance, protect, and conserve the water and associated land resources of the Potomac River basin and its tributaries through regional and interstate cooperation.

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 and Ohio Canal, no version of any scheme was ever built. In most cases the proposed reservoir would have extended upriver to Harpers Ferry, West Virginia. The project was part of a program of as many as sixteen major dams in the Potomac watershed, most of which were never built.

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 opportunities. Beginning in 1921 the Corps studied a variety of proposals for an ambitious program of dam construction on the Potomac and its tributaries, which proposed as many as sixteen major dam and reservoir projects. The most ambitious proposals would have created a nearly continuous chain of reservoirs from tidewater to Cumberland, Maryland. The 1938 program was focused on flood control, on the heels of a major flood in 1936. The reformulated 1963 program focused on water supply and quality, mitigating upstream pollution from sewage and coal mine waste.

References

  1. "President Clinton: Celebrating America's Rivers". American Heritage Rivers. July 30, 1998. Archived from the original on April 28, 2014. Retrieved February 5, 2014.
  2. 1 2 3 4 5 "USGS 01646500 POTOMAC RIVER NEAR WASH, DC LITTLE FALLS PUMP STA". nwis.waterdata.usgs.gov. National Weather Service (NOAA). 2019. Retrieved March 23, 2019.
  3. "(Arakawa - Potomac sister rivers)". Interstate Commission on the Potomac River Basin. January 27, 2012. Archived from the original on December 27, 2013. Retrieved September 23, 2016.
  4. 1 2 3 4 5 6 U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map Archived March 29, 2012, at the Wayback Machine . Retrieved August 15, 2011
  5. 1 2 "Facts & FAQs". Interstate Commission on the Potomac River Basin (ICPRB), Rockville, MD. September 16, 2009. Archived from the original on January 15, 2010. Retrieved February 5, 2010.
  6. "Historic Crests for Potomac near Washington, DC (Little Falls)". water.weather.gov/ahps/. National Weather Service (NOAA). 2019. Retrieved March 23, 2019.
  7. 1 2 "1936 Flood Retrospective: The Flood of March 17-19 1936". weather.gov. NWS. March 16, 2016. Retrieved March 26, 2019.
  8. Little, Becky (September 14, 2018). "World War II-Era Flood Was the Worst in D.C.'s History". www.history.com. A&E Television Networks, LLC. Retrieved March 23, 2019.
  9. 1 2 "Geology of Potomac Heritage National Scenic Trail". Potomac Heritage. NPS. 2019. Retrieved March 25, 2019.
  10. Jaworski, Norbert A. (July 20, 2015). "The Potomac River Basin and its Estuary: Landscape Loadings and Water Quality Trends, 1895 – 2005" (PDF). www.potomacriver.org. Interstate Commission on the Potomac River Basin(ICPRB). Retrieved March 30, 2019.
  11. Bright, William (2004). Native American Placenames of the United States. University of Oklahoma Press. p. 396. ISBN   978-0-8061-3598-4. Archived from the original on May 11, 2016.
  12. Legends of Loudoun: An account of the history and homes of a border county of Virginia's Northern Neck, Harrison Williams, p. 26.
  13. 1 2 Achenbach, Joel (2004). The Grand Idea: George Washington's Potomac and the Race to the West . Simon and Schuster. pp.  35–36. ISBN   978-0-684-84857-0.
  14. Hagemann, James A. (1988). The Heritage of Virginia. The Donning Company, 2nd edition, 297 p. ISBN   0-89865-255-3.
  15. "Potomac River". Geographic Names Information System . United States Geological Survey.
  16. "Chesapeake Swan Song exhibition opens April 11 at CBMM". Chesapeake Bay Maritime Museum. January 26, 2015. Archived from the original on February 28, 2018. Retrieved February 28, 2018.
  17. Reed, John Calvin. "The River and the Rocks: The Geologic Story of Great Falls and the Potomac River Gorge" (PDF). pubs.usgs.gov. USGS. Retrieved March 24, 2019.
  18. Peck, Garrett (2012). The Potomac River: A History and Guide. Charleston, SC: The History Press. p. 18. ISBN   978-1-60949-600-5.
  19. Hahn, Thomas (1984). The Chesapeake & Ohio Canal: Pathway to the Nation's Capital. Metuchen, NJ: Scarecrow Press. ISBN   0-8108-1732-2.
  20. Ways, Harry C. (1996). The Washington Aqueduct: 1852-1992. (Baltimore, MD: U.S. Army Corps of Engineers, Baltimore District)
  21. Washington Aqueduct
  22. "The 10 Most Populous Metro Areas : July 1, 2015" (PDF). www.census.gov. US Census Bureau. July 2015. Retrieved April 9, 2019.
  23. Carey, Frank (December 4, 1963). "Potomac Dam Is Opposed By Virginians". Fredericksburg Free-Lance Star. Retrieved November 13, 2009.
  24. Grey, Karen (March 2018). "Canal Engineering from Dam 3 to Harpers Ferry" (PDF). candocanal.org. 'Along the Towpath', C&O Canal Association. Retrieved March 16, 2019.
  25. Holdsworth, Bill (April 2013). "Level 51 (Dam #6)". candocanal.org. C&O Canal Association. Retrieved March 16, 2019.
  26. Unrau, Harland D. (August 2007). "Historical Resource Study: Chesapeake & Ohio Canal" (PDF). US Department of the Interior, National Park Service. pp. 208, 470. Retrieved March 16, 2019.
  27. Joel Achenbach (May 5, 2002). "America's River". The Washington Post. pp. W12. Archived from the original on September 16, 2002.
  28. "Jennings Randolph Lake, MD & WV" (PDF). www.nab.usace.army.mil. USACE (United States Corps of Engineers). February 2015. Retrieved April 5, 2019.
  29. Scott, Pamela (2007), "Capital Engineers: The U.S. Army Corps of Engineers in the Development of Washington, D.C., 1790–2004." Archived February 26, 2012, at the Wayback Machine (Washington, DC: U.S. Army Corps of Engineers.) Publication No. EP 870-1-67. p. 256.
  30. "USGS 01646500 POTOMAC RIVER NEAR WASH, DC LITTLE FALLS PUMP STA". USGS. 2019. Retrieved March 12, 2019.
  31. 1 2 ICPRB. "Potomac Timeline." Archived January 5, 2011, at the Wayback Machine Updated 2008-04-15.
  32. District of Columbia Water and Sewer Authority. Washington, DC. "History of Blue Plains Wastewater Treatment Plant." Archived March 17, 2015, at the Wayback Machine Accessed 2010-09-28.
  33. "STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1930 - 2018, BY WATER YEAR, near WDC". USGS. 2019. Retrieved March 13, 2019.
  34. U.S. Fish and Wildlife Service. Annapolis, MD (2009). "Intersex fish: Endocrine disruption in smallmouth bass." Archived March 3, 2016, at the Wayback Machine
  35. Fahrenthold, David A. (November 13, 2007). "Potomac Recovery Deemed At Risk". The Washington Post. Archived from the original on July 1, 2011. Retrieved November 13, 2007.
  36. "Potomac Report Card". Potomac Conservancy. March 28, 2018. Retrieved March 26, 2019.
  37. Lang, Marissa J. "Taking a swim in the Potomac? Weekly readings will reveal water quality and bacteria levels." 2019-03-30. Retrieved 2019-03-30. (Archived by WebCite® at https://www.webcitation.org/77GYx0Kjp)
  38. Need a bigger boat: 35-pound bass caught on the Potomac River. Washington Post. 2019-04-03. URL:https://wtop.com/local/2019/03/need-a-bigger-boat-35-pound-bass-caught-on-the-potomac-river/. Accessed: 2019-04-03. (Archived by WebCite® at https://www.webcitation.org/77MQbQA7K)
  39. U.S. Supreme Court. Virginia v. Maryland, 540 U.S. 56 (2003)
  40. Maryland v. West Virginia, 217 U.S. 1 (1910)
  41. Maryland v. West Virginia, 217 U.S. 577 (1910)
  42. Potomac snakeheads not related to others Archived September 30, 2007, at the Wayback Machine Associated Press, Baltimore Sun, April 27, 2007.
  43. "Northern Snakehead". Virginia Department of Wildlife Resources.
  44. Jim Cummins (2013). "FISHES OF THE FRESHWATER POTOMAC" (PDF). www.potomacriver.org. Interstate Commission on the Potomac River Basin . Retrieved February 27, 2018.
  45. "Sharks! Watermen catch two 8-footers on same day". somdnews.com. Archived from the original on September 10, 2012. Retrieved December 17, 2011.
  46. "THE POTOMAC RIVER AMERICAN SHAD RESTORATION PROJECT" (PDF). www.potomacriver.org. Interstate Commission on the Potomac River Basin. March 2014. Retrieved February 26, 2018.
  47. "The Mysterious Dolphins of the Potomac". 2017. Archived from the original on September 30, 2017. Retrieved February 26, 2018.
  48. "Potomac-Chesapeake Dolphin Project". 2018. Archived from the original on April 6, 2017. Retrieved February 26, 2018.
  49. Topographic map of the confluence of the North and South branches of the Potomac River Archived March 12, 2007, at the Wayback Machine
  50. Morrison, Charles (1971), Wappatomaka: A Survey of the History and Geography of the South Branch Valley, McClain Printing Co.: Parsons, W.Va..
  51. "Potomac Riverkeeper Network". www.potomacriverkeepernetwork.org. Potomac Riverkeeper Network. 2019. Retrieved March 25, 2019.
  52. "Potomac River Basin Fact Sheet" (PDF). www.potomacriver.org. Interstate Commission on the Potomac River Basin (ICPRB). October 2015. Retrieved March 28, 2019.
  53. "Water, Water ... " by Larry Van Dyne, Washingtonian Magazine (March 2007)
  54. "Sources of Northern Virginia Drinking Water", Virginia Places
  55. Great Falls Geology, National Park Service, April 10, 2015
  56. Michael J. Kunk, et al., Multiple Paleozoic Metamorphic Histories, Fabrics, and Faulting in the Westminster and Potomac Terranes, Central Appalachian Piedmont, Northern Virginia and Southern Maryland, U.S. Geological Survey, 23 November 2016
  57. Paul Bierman, et. al., Great Falls is 30,000 Years Old, Paper No. 35-5, Session No. 35, Geomorphic Process Rates on the Passive Margin, March 26, 2004. Geological Society of America Abstracts with Programs, Vol. 36, No. 2, p. 94
  58. Chapter One: Introduction

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; ISBN   0-8018-9032-2; ISBN   978-0-8018-9032-1
  • Smith, J. Lawrence, The Potomac Naturalist: The Natural History of the Headwaters of the Historic Potomac (1968), Parsons, WV: McClain Printing Co.; ISBN   0-87012-023-9; ISBN   978-0-87012-023-7