Potomac River


The Potomac River is found within the Mid-Atlantic region of the United States and flows from the Potomac Highlands into the Chesapeake Bay. The river is approximately long, with a drainage area of about 14,700 square miles. 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.
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". 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 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, 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.
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 wide at its mouth, between Point Lookout, Maryland, and Smith Point, Virginia, before flowing into the Chesapeake Bay.

History

"Potomac" is a European spelling of Patawomeck, the Algonquian name of a Native American village on its southern bank. Native Americans had different names for different parts of the river, calling the river above Great Falls Cohongarooton, meaning "honking geese" and "Patawomke" below the Falls, meaning "river of swans". The spelling of the name has taken many forms over the years from "Patawomeck" 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.
s 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, 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.
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.

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, 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. Several other dams were proposed for the Potomac and its tributaries.
Dams on the Potomac River


Operational
Non-Operational
  • aka C&O Feeder Dam No. 2
  • aka C&O Feeder Dam No. 3
Planned, but never built
  • C&O Feeder Dam No. 7 and Guard Lock No. 7 were proposed to be located near milepost 164, close to the mouth of the South Branch of the Potomac, but were never built due to financial considerations.

When detailed studies were issued by the Corps in the 1950s, they met sustained opposition, led by U.S. Supreme Court Justice William O. Douglas, resulting in the plans' abandonment. The only dam project that did get built was Jennings Randolph Lake on the North Branch.
The Corps built a supplementary water intake for the Washington Aqueduct at Little Falls in 1959.
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.
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. 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.
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.
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 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.

Legal issues

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 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 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. A Special Master appointed by the Supreme Court to investigate recommended the case be settled in favor of Virginia, citing the language in the 1785 Compact and the 1877 Award. On December 9, 2003, the Court agreed in a 7–2 decision.
The original charters are silent as to which branch from the upper Potomac serves as the boundary, but this was settled by the 1785 Compact. When West Virginia seceded from Virginia in 1863, the question of West Virginia's succession in title to the lands between the branches of the river was raised, as well as title to the river itself. Claims by Maryland to West Virginia land north of the South Branch and by West Virginia to the Potomac's high-water mark were rejected by the Supreme Court in two separate decisions in 1910.

Flora of the Potomac River Basin

Fauna of the Potomac River and its Basin

Fish

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. Many types of sunfish are also present in the Potomac and its headwaters. Although rare, bull sharks can be found.
After having been depressed for many decades, the river's population of American Shad is currently re-bounding as a result of the ICPRB's successful "American Shad Restoration Project" that was begun in 1995. In addition to stocking the river with more than 22 million shad fry, the Project supervised 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.

Bowfin ([Amiidae])


* denotes naturalized species;
Sources:
! Tidal freshwater fish of the Potomac River

Mullets ([Mugilidae])

Mugil cephalus

Drums ([Sciaenidae])

Leiostomus xanthurus
Spotted seatrout Cynoscion nebulosus
Atlantic Croaker Micropogonias undulatus
Red drum Sciaenops ocellata

Soles ([Soleidae])

Trinectes maculatus

Sharks ([Carcharhinidae])

Carcharhinus leucas

Sources:
Mammals of the Potomac River Basin



* denotes naturalized species
Sources:
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 and panthers 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 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.
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 , more than 500 individual members of the species have been identified in the Potomac during this period.

Birds

Birds of the Potomac River Basin

Reptiles

Turtles of the Potomac River Basin


Bog turtle Glyptemys muhlenbergii
Chinese softshell turtle * Pelodiscus sinensis *
Coastal plain cooter Pseudemys concinna floridana
Cumberland slider Trachemys scripta troostii
Eastern box turtle Terrapene carolina carolina
Eastern chicken turtle Deirochelys reticularia reticularia
Eastern mud turtle Kinosternon subrubrum subrubrum
Eastern musk turtle Sternotherus odoratus
Eastern painted turtle Chrysemys picta picta
Eastern river cooter Pseudemys concinna concinna
Eastern spiny softshell turtle Apalone spinifera spinifera
Green sea turtle Chelonia mydas
Gulf Coast spiny softshell turtle * Apalone spinifera aspera *
Hawksbill sea turtle Eretmochelys imbricata
Kemp's ridley sea turtle Lepidochelys kempii
Leatherback sea turtle Dermochelys coriacea
Loggerhead sea turtle Caretta caretta
Mississippi map turtle* Graptemys pseudogeographica kohnii *
Northern map turtle Graptemys geographica
Northern diamond-backed terrapin Malaclemys terrapin terrapin
Northern red-bellied cooter Pseudemys rubriventris
Red-eared slider * Trachemys scripta elegans *
Snapping turtle Chelydra serpentina
Spotted turtle Clemmys guttata
Striped mud turtle Kinosternon baurii
Stripe-necked musk turtle Sternotherus minor peltifer
Wood turtle Glyptemys insculpta
Yellow-bellied slider Trachemys scripta scripta

* denotes naturalized species
Sources:

https://dwr.virginia.gov/wp-content/uploads/virginia-native-naturalized-species.pdf

http://dnr.maryland.gov/wildlife/Documents/herpchecklist.pdf

Snakes of the Potomac River basin


Northern copperhead Agkistrodon contortrix mokasen
Timber rattlesnake Crotalus horridus
Northern watersnake Nerodia sipedon sipedon
Red-bellied watersnake Nerodia erythrogaster erythrogaster
Queen snake Regina septemvittata
Eastern smooth earthsnake Virginia valeriae valeriae
Mountain earthsnake Virginia valeriae pulchra
Northern brown snake Storeria dekayi dekayi
Northern Red-bellied Snake Storeria occipitomaculata occipitomaculata
Eastern garter snake Thamnophis sirtalis sirtalis
Common ribbonsnake Thamnophis sauritus sauritus
Southern ring-necked snake Diadophis punctatus punctatus
Northern ring-necked snake Diadophis punctatus edwardsi
Eastern worm snake Carphophis amoenus amoenus
Smooth green snake Opheodrys vernalis
Northern rough greensnake Opheodrys aestivus aestivus
Eastern hog-nosed snake Heterodon platirhinos
Rainbow snake Farancia erytrogramma erytrogramma
Northern Black Racer Coluber constrictor constrictor
Red cornsnake Pantherophis guttatus
Eastern ratsnake Pantherophis alleghaniensis
Mole kingsnake Lampropeltis calligaster rhombomaculata
Eastern kingsnake Lampropeltis getula getula
Eastern kilksnake Lampropeltis triangulum triangulum
Coastal Plain Milksnake Lampropeltis triangulum elapsoides
Northern scarletsnake Cemophora coccinea copei

Sources:

http://dnr.maryland.gov/wildlife/Documents/herpchecklist.pdf

A Guide to the Snakes of Virginia 2002; by Michael J Pinder

Lizards of the Potomac River Basin


Eastern Fence Lizard Sceloporus undulatus
Eastern Six-lined Racerunner Aspidoscelis sexlineata sexlineata
Little Brown Skink Scincella lateralis
Northern Coal Skink Plestiodon anthracinus anthracinus
Common Five-lined Skink Plestiodon fasciatus
Broad-headed Skink Plestiodon laticeps

Sources:
  • https://dwr.virginia.gov/wp-content/uploads/virginia-native-naturalized-species.pdf
  • http://dnr.maryland.gov/wildlife/Documents/herpchecklist.pdf

Amphibians

Salamanders of the Potomac River Basin


Common Mudpuppy Necturus maculosus maculosus
Eastern Hellbender Cryptobranchus alleganiensis alleganiensis
Marbled Salamander Ambystoma opacum
Jefferson Salamander Ambystoma jeffersonianum
Spotted Salamander Ambystoma maculatum
Eastern Tiger Salamander Ambystoma tigrinum tigrinum
Red-spotted Newt Notophthalmus viridescens viridescens
Eastern Red-backed Salamander Plethodon cinereus
Wehrle's Salamander Plethodon wehrlei
Northern slimy salamander Plethodon glutinosus
Valley and ridge salamander Plethodon hoffmani
Seal Salamander Desmognathus monticola monticola
Northern Dusky Salamander Desmognathus fuscus
Allegheny Mountain Dusky Salamander Desmognathus ochrophaeus
Northern Red Salamander Pseudotriton ruber ruber
Eastern Mud Salamander Pseudotriton montanus montanus
Northern Spring Salamander Gyrinophilus porphyriticus porphyriticus
Northern Two-lined Salamander Eurycea bislineata
Southern Two-lined Salamander Eurycea cirrigera
Long-tailed salamander Eurycea longicauda longicauda
Four-toed Salamander Hemidactylium scutatum
Green Salamander Aneides aeneus

Sources:
  • https://dwr.virginia.gov/wp-content/uploads/virginia-native-naturalized-species.pdf
  • http://dnr.maryland.gov/wildlife/Documents/herpchecklist.pdf
Frogs and toads of the Potomac River Basin


Upland Chorus Frog Pseudacris feriarum
New Jersey Chorus Frog Pseudacris kalmi
Northern Spring Peeper Pseudacris crucifer
Mountain Chorus Frog Pseudacris brachyphona
Eastern Cricket Frog Acris crepitans crepitans
Green Treefrog Hyla cinerea
Gray Treefrog Hyla versicolor
Cope's Gray Treefrog Hyla chrysoscelis
Barking Treefrog Hyla gratiosa
Carpenter Frog Lithobates virgatipes
Wood Frog Lithobates sylvaticus
Northern Leopard Frog* Lithobates pipiens*
Southern Leopard Frog Lithobates sphenocephalus utricularius
Pickerel Frog Lithobates palustris
Northern Green Frog Lithobates clamitans melanota
American Bullfrog Lithobates catesbeiana
Eastern spadefoot toad Scaphiopus holbrookii
Eastern American Toad Anaxyrus americanus americanus
Fowler's Toad Anaxyrus fowleri
Eastern Narrow-mouthed Toad Gastrophryne carolinensis

* denotes naturalized species
Sources:
  • https://dwr.virginia.gov/wp-content/uploads/virginia-native-naturalized-species.pdf
  • http://dnr.maryland.gov/wildlife/Documents/herpchecklist.pdf

The Potomac River System

North Branch Potomac River

The source of the North Branch Potomac River is at the Fairfax Stone located at the junction of Grant, Tucker and Preston counties in West Virginia.
From the Fairfax Stone, the North Branch Potomac River flows 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. downstream from its source, the North Branch is joined by the South Branch between Green Spring and South Branch Depot, West Virginia from whence it flows past Hancock, Maryland and turns southeast once more on its way toward Washington, D.C., and the Chesapeake Bay.
The 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.
Tributaries of the North Branch of the Potomac River


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, 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.

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.
Places settled in the South Branch valley bearing variants of "Wappatomaka" include Wappocomo farm built in 1774 and the unincorporated hamlet of Wappocomo 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 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, followed by Sandy Ridge along U.S. Route 220. North of the confluence of the South Branch with Smith Creek, the river flows along Town Mountain 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 and Cave Mountain, the South Branch bends around the Eagle Rock outcrop and continues its flow northward into Grant County. Into Grant, the South Branch follows the western side of Cave Mountain through the long Smoke Hole Canyon, until its confluence with the North Fork at Cabins, where it flows east to Petersburg. At Petersburg, the South Branch is joined with the South Branch Valley Railroad, which it parallels until its mouth at Green Spring.
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 and to its east by Sawmill Ridge. 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 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 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, the South Branch creates a series of bends and flows to the northeast by Springfield through Blue's Ford. After two additional horseshoe bends, 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.
Tributaries of the South Branch of the Potomac River


North Fork South Branch Potomac River

The North Fork South Branch Potomac River, long, 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. From Circleville, the North Fork flows northeast through Pendleton County between the Fore Knobs to its west and the River Knobs, 2,490 feet 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 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 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.
Tributaries of the Upper Potomac River


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.
Tributaries of the Lower Potomac River


Tidal Potomac River

The Tidal Potomac River lies below the Fall Line. This 108-mile 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.
Tributaries of the Tidal Potomac River




Additional images

Upper and lower Potomac

Tidal Potomac

Other

Works cited