Potomac River - WikiHQ

The Potomac River () is in the Mid-Atlantic region of the United States and flows from the Potomac Highlands in West Virginia to Chesapeake Bay in Maryland. It is long, with a drainage area of , and is the fourth-largest river along the East Coast of the United States. More than 6 million people live within its watershed.

The river forms the boundary separating the jurisdictions on its left descending bank (Maryland and Washington, D.C.) from those on its right descending bank (West Virginia and 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. All navigable parts of the river were designated as a National Recreation Trail in 2006, and the National Oceanic and Atmospheric Administration (NOAA) designated an portion of the river in Charles County, Maryland, as the Mallows Bay–Potomac River National Marine Sanctuary in 2019.

The river has significant historical and political significance, as the nation's capital of Washington, D.C. is located on its banks, as is Mount Vernon, the home of George Washington. During the American Civil War, the river became the boundary between the Union and the Confederacy, and the Union's largest army, the Army of the Potomac, was named after the river.

Course

thumb|In [[Washington, D.C., the Potomac is crossed by the Arlington Memorial Bridge.]]

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 . Along the way the following tributaries drain into the Potomac: North Branch Potomac River, South Branch Potomac River, Town Creek, Little Cacapon River, Sideling Hill Creek, Cacapon River, Sir Johns Run, Warm Spring Run, Tonoloway Creek, Fifteenmile Creek, Sleepy Creek, Cherry Run, Back Creek, Conococheague Creek, and Opequon Creek.

Lower Potomac River

thumb|left|Confluence of the Potomac and Shenandoah at Harpers Ferry

This section covers the Potomac from just above Harpers Ferry in West Virginia down to Little Falls, Maryland on the border between Maryland and Washington, DC. Along the way the following tributaries drain into the Potomac: Antietam Creek, Shenandoah River, Catoctin Creek (Virginia), Catoctin Creek (Maryland), Tuscarora Creek, Monocacy River, Little Monocacy River, Broad Run, Goose Creek, Broad Run, Horsepen Branch, Little Seneca Creek, Tenmile Creek, Great Seneca Creek, Old Sugarland Run, Muddy Branch, Nichols Run, Watts Branch, Limekiln Branch, Carroll Branch, Pond Run, Clarks Branch, Mine Run Branch, Difficult Run, Bullneck Run, Rock Run, Scott Run, Dead Run, Turkey Run, Cabin John Creek, Minnehaha Branch, and Little Falls Branch.

Tidal Potomac River

thumb|right|View southwest across the tidal Potomac River from the south end of [[Maryland Route 254|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.

Along the way the following tributaries drain into the Potomac: Pimmit Run, Gulf Branch, Donaldson Run, Windy Run, Spout Run, Maddox Branch, Foundry Branch, Rock Creek, Rocky Run, Tiber Creek, Roaches Run, Washington Channel, Anacostia River, Four Mile Run, Oxon Creek, Hunting Creek, Broad Creek, Henson Creek, Swan Creek, Piscataway Creek, Little Hunting Creek, Dogue Creek, Accotink Creek, Pohick Creek, Pomonkey Creek, Occoquan River, Neabsco Creek, Powell's Creek, Mattawoman Creek, Chicamuxen Creek, Quantico Creek, Little Creek, Chopawamsic Creek, Tank Creek, Aquia Creek, Potomac Creek, Nanjemoy Creek, Chotank Creek, Port Tobacco River, Popes Creek, Gambo Creek, Clifton Creek, Piccowaxen Creek, Upper Machodoc Creek, Wicomico River, Cobb Island, Monroe Creek, Mattox Creek, Popes Creek, Breton Bay, Leonardtown, St. Marys River, Yeocomico River, Coan River, 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

thumb|left|Captain John Smith's 1608 map

The Potomac River has long been inhabited by Native Americans, including being the periphery of the Delaware Adena culture. Precontact, the region was governed by the Algonquian Piscataway confederacy and their allies as warfare in the region increased. This led to the formation of a more complex political system led by the Tayac with countless Werowances governing local affairs. Their confederacy fractured precontact into smaller werowancies and alliances as power shifted south to the Powhatan confederacy.

"Potomac" is a European spelling of Patawomeck, the Algonquian name of a Native American village on its southern bank. Native Americans had different names for different parts of the river, calling the river above Great Falls Cohongarooton, meaning "honking geese" and "Patawomke" below the Falls, meaning "river of swans". In 1608, Captain John Smith explored the river now known as the Potomac and made drawings of his observations which were later compiled into a map and published in London in 1612. This detail from that map shows his rendition of the river that the local tribes had told him was called the "Patawomeck". The spelling of the name has taken many forms over the years from "Patawomeck" (as on Captain John Smith's map) to "Patomake", "Patowmack", and numerous other variations in the 18th century and now "Potomac".

The 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, the first President of the United States, was born in, surveyed, and spent most of his life within, the Potomac basin. There is an apocryphal legend that Washington threw a silver dollar all the way across the river as a youth (even though the first silver dollar wasn't minted until five years before Washington's death). All of Washington, D.C., the nation's capital city, also lies within the watershed. The First United States Congress by act of July 16, 1790 stated that the nation's capital was to be located on the river. 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.

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.

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. 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.

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.

thumb|The Potomac River surges over the deck of [[Chain Bridge (Potomac River)|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, Several other dams were proposed for the Potomac and its tributaries.

{| class="wikitable mw-collapsible mw-collapsed" style="margin:auto;"

! style="border-width:4px; background:azure;"|Dams on the Potomac River 

Operational

Little Falls Dam (Potomac River) aka Brookmont Dam (at C&O Canal milepost 5.6, upstream of Chain Bridge)
Potomac Aqueduct Dam (at C&O Canal milepost 17.5, upstream of Great Falls)
C&O Feeder Dam No. 4 (at C&O Canal milepost 84, downstream of Williamsport, MD)
Honeywood Dam aka C&O Feeder Dam No. 5 (at C&O Canal milepost 106, upstream of Williamsport, MD)
Cumberland Dam aka Feeder Dam No. 8 (on North Branch of Potomac River, 40 miles downstream of Fairfax Stone)
Jennings Randolph Dam (on North Branch of the Potomac River, 27 miles downstream of Fairfax Stone)

Non-Operational

C&O Feeder Dam No. 1 (C&O Canal milepost 5.6, upstream of Chain Bridge near Lock 6; associated with Little Falls Skirting Canal [http://www.riverexplorer.com/details.php?id=531] )
Seneca Dam aka C&O Feeder Dam No. 2 (at C&O Canal milepost 22, near Violette's Lock)
Armory Dam aka C&O Feeder Dam No. 3 (at C&O Canal milepost 62, upstream of Harpers Ferry, WV)
C&O Feeder Dam No. 6 (at C&O Canal milepost 134, west of Hancock, MD)

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.

</blockquote>

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 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 compact was amended in 1970 to include coordination of water supply issues and land use issues related to water quality.

right|thumb|[[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 the 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.

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 group has issued a grade of "B" since 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 was seen as a further indicator of the continuing improvement in the health of the river.

On January 19, 2026, a large sewage pipe, the Potomac Interceptor, ruptured near Lock 10 of the C&O Canal and the Clara Barton Parkway, causing a spill of 300 million gallons into the river. (The interceptor sewer originates in the Virginia and Maryland suburbs. One section of the system runs in a reinforced concrete pipe next to the canal, and transports wastewater to the Blue Plains Advanced Wastewater Treatment Plant in Washington.) The contamination from the spill is thousands of times higher than what is considered safe for human use. Work has been done to redirect the sewage into a contained part of the canal.

{| class="wikitable" style="width:500px; margin:auto;"

! colspan="8" style="background:azure;"|Top Ten Historic Crests of the Potomac River, 1877–2017

| align=center |

! align=center |

| align=center |

| colspan="8" style="text-align:center; background:white;"|Source: National Weather Service

Discharge

[[File:Potomac River Discharge at Little Falls 1931-2017.jpg|thumb|left|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.

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 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 1785 Mount Vernon Compact and the 1877 Black-Jenkins Award which granted Maryland the river bank-to-bank from the low-water mark on the Virginia side while permitting Virginia full riparian rights short of obstructing navigation.

From 1957 to 1996, the Maryland Department of the Environment (MDE) routinely issued permits applied for by Virginia entities concerning the use of the Potomac. However, in 1996 the MDE denied a permit submitted by the Fairfax County Water Authority to build a water intake 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.

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.

Fauna

Fish

thumb|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. Many species of sunfish are also present in the Potomac and its headwaters. Although rare, bull sharks can be found.

After having been depressed for many decades, the river's population of American shad is currently re-bounding as a result of the ICPRB's successful "American Shad Restoration Project" that was begun in 1995. In addition to stocking the river with more than 22 million shad fry, the Project supervised the construction of a fishway that was built to facilitate the passage of adults around the Little Falls Dam on the way to their traditional spawning grounds upstream.

{| class="wikitable mw-collapsible mw-collapsed"

! Freshwater fish of the Potomac River

Bowfin (Amiidae)

Bowfin Amia calva

Catfishes (Ictaluridae)

White bullhead catfish Ameiurus catus
Yellow bullhead catfish Ameiurus natalis
Brown bullhead catfish Ameiurus nebulosus
Channel catfish Ictalurus punctatus
Tadpole madtom Noturus gyrinus
Margined madtom Noturus insignis
Blue catfish*Ictalurus furcatus*
Flathead catfish*Pylodictis olivaris*

Eels (Anguillidae)

American eel Anguilla rostrata

Gars (Lepisosteidae)

Longnose gar Lepisosteus osseus

Herrings (Clupeidae)

Blueback herring Alosa aestivalis
Hickory shad Alosa mediocris
Alewife Alosa pseudoharengus
American shad Alosa sapidissima
Gizzard shad Dorosoma cepedianum
Threadfin shad Dorosoma petenense

Killifishes (Fundulidae)

Banded killifish Fundulus diaphanus
Mummichog killifish Fundulus heteroclitus
Spotfin killifish Fundulus luciae
Striped killifish Fundulus majalis
Rainwater killifish Lucania parva

Pupfish (Cyprinodontidae)

Sheepshead minnow Cyprinodon variegatus

Lampreys (Petromyzontidae)

Least brook lamprey Lampetra aepyptera
American brook lamprey Lampetra appendix
Sea lamprey Petromyzon marinus

Minnows (Cyprinidae)

Central stoneroller Campostoma anomalum
Goldfish Carassius auratus
Redside dace Clinostomus elongatus
Rosyside dace Clinostomus funduloides
Grass carp Ctenopharyngodon idella
Satinfin shiner Cyprinella analostana
Spotfin shiner Cyprinella spiloptera
Common carp Cyprinus carpio
Cutlips minnow Exoglossum maxillingua
Eastern silvery minnow Hybognathus regius
Striped shiner Luxilus chrysocephalus
Common shiner Luxilus cornutus
Allegheny pearl dace Margariscus margarita
River chub Nocomis micropogon
Golden shiner Notemigonus crysoleucas
Comely shiner Notropis amoenus
Emerald shiner Notropis atherinoides
Bridle shiner Notropis bifrenatus
Silverjaw minnow Notropis buccatus
Ironcolor shiner Notropis chalybaeus
Spottail shiner Notropis hudsonius
Swallowtail shiner Notropis procne
Rosyface shiner Notropis rubellus
Bluntnose minnow Pimephales notatus
Fathead minnow Pimephales promelas
Eastern blacknose dace Rhinichthys atratulus
Longnose dace Rhinichthys cataractae
Creek chub Semotilus atromaculatus
Fallfish Semotilus corporalis
Bluehead chub Nocomis leptocephalus
Mimic shiner Notropis volucellus

Mudminnows (Umbridae)

Eastern mudminnow Umbra pygmaea

Perches (Percidae)

Greenside darter Etheostoma blennioides
Rainbow darter Etheostoma caeruleum
Fantail darter Etheostoma flabellare
Swamp darter Etheostoma fusiforme
Johnny darter Etheostoma nigrum
Tessellated darter Etheostoma olmstedi
Glassy darter Etheostoma vitreum
Banded darter Etheostoma zonale
Yellow perch Perca flavescens
Common logperch Percina caprodes
Stripeback darter Percina notogramma
Shield darter Percina peltata
Walleye Sander vitreum

Percopsids (Percopsidae)

Trout-perch Percopsis omiscomaycus

Pikes (Esocidae)

Redfin pickerel Esox americanus
Northern pike Esox lucius
Muskellunge Esox masquinongy
Chain pickerel Esox niger

Pirate perch (Aphredoderidae)

Pirate perch Aphredoderus sayanus

Poeciliids (Poeciliidae)

Eastern mosquitofish Gambusia holbrooki
Guppy Poecilia reticulata

Pupfish (Cyprinodontidae)

Sheepshead minnow Cyprinodon variegatus

Sculpins (Cottidae)

Mottled sculpin Cottus bairdii
Blue Ridge sculpin Cottus caeruleomentum
Potomac sculpin Cottus girardi

Silversides (Atherinopsidae)

Inland silverside Menidia beryllina

Smelts (Osmeridae)

Rainbow smelt Osmerus mordax

Snakeheads (Channidae)

Northern snakehead*Channa argus*

Sturgeons (Acipenseridae)

Shortnose sturgeon Acipenser brevirostrum
Atlantic sturgeon Acipenser oxyrhinchus

Suckers (Catostomidae)

Quillback Carpiodes cyprinus
White sucker Catostomus commersoni
Creek chubsucker Erimyzon oblongus
Northern hogsucker Hypentelium nigricans
Golden redhorse Moxostoma erythrurum
Shorthead redhorse Moxostoma macrolepidotum
Torrent sucker Thoburnia rhothoeca

Sunfishes (Centrarchidae)

Mud sunfish Acantharcus pomotis
Rock bass Amblopites rupestris
Flier sunfish Centrarchus macropterus
Blackbanded sunfish Enneacanthus chaetodon
Bluespotted sunfish Enneacanthus gloriosus
Banded sunfish Enneacanthus obesus
Redbreast sunfish Lepomis auritus
Green sunfish Lepomis cyanellus
Pumpkinseed sunfish Lepomis gibbosus
Warmouth sunfish Lepomis gulosus
Bluegill sunfish Lepomis macrochirus
Longear sunfish Lepomis megalotis
Redear sunfish Lepomis microlophus
Smallmouth bass Micropterus dolomieu
Largemouth bass Micropterus salmoides
White crappie Pomoxis annularis
Black crappie Pomoxis nigromaculatus

Temperate basses (Moronidae)

White perch Morone americana
Striped bass Morone saxatilis

Trout and whitefish (Salmonidae)

Rainbow trout (Oncorhynchus mykiss)
Brown trout (Salmo trutta)

</blockquote>

  *denotes naturalized species;

Sources:

Dnr.state.md: Fish key of native species
http://www.potomacriver.org/wp-content/uploads/2014/11/MasterFreshFishList0213.pdf

{| class="wikitable mw-collapsible mw-collapsed"

! Tidal freshwater fish of the Potomac River

| <blockquote>

Mullets (Mugilidae)

Striped mullet Mugil cephalus

Drums (Sciaenidae)

Spot Leiostomus xanthurus

Spotted seatrout Cynoscion nebulosus

Atlantic Croaker Micropogonias undulatus

Red drum Sciaenops ocellata

Soles (Soleidae)

Hogchoker Trinectes maculatus

Sharks (Carcharhinidae)

Bull shark Carcharhinus leucas

</blockquote>

Sources:

Dnr.state.md: Fish key of native species
http://www.potomacriver.org/wp-content/uploads/2014/11/MasterFreshFishList0213.pdf

Mammals

thumb|left|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.

{| class="wikitable mw-collapsible mw-collapsed"

! Mammals of the Potomac River Basin

Bats
Little brown bat Myotis lucifugus
Indiana bat Myotis sodalis
Eastern small-footed bat Myotis leibii
Northern long-eared bat Myotis septentrionalis
Silver-haired bat Lasionycteris noctivagans
Tricolored bat Perimyotis subflavus
Big brown bat Eptesicus fuscus
Red bat Lasiurus borealis
Hoary bat Lasiurus cinereus
Evening bat Nycticeius humeralis
Bears
American black bear Ursus americanus
Beavers
American beaver Castor canadensis
Cats
Bobcat Lynx rufus
Cougar, Puma concolor extirpated
Eastern cougar, P. c. couguar extinct
Canids
Red fox Vulpes vulpes
Gray fox Urocyon cinereoargenteus
Coyote Canis latrans
Gray wolf Canis lupus extirpated
Red wolf Canis rufus extirpated
Ungulates
Sika deer*Cervus nippon *
Elk Cervus canadensis reintroduced
Eastern elk C. c. canadensis extinct
Rocky Mountain elk C. c. canadensis introduced
White-tailed deer Odocoileus virginianus
American bison Bison bison extirpated
Jumping mice
Meadow jumping mouse Zapus hudsonius
Woodland jumping mouse Napaeozapus insignis
Lemmings
Southern bog lemming Synaptomys cooperi
Marine Mammals
Bottlenose dolphin Tursiops truncatus
Moles
Hairy-tailed mole Parascalops breweri
Eastern mole Scalopus aquaticus
Southeastern star-nosed mole Condylura cristata parva
Muskrats
Muskrat Ondatra zibethicus
New World Mice and Rats
Marsh rice rat Oryzomys palustris
Deer mouse Peromyscus maniculatus
White-footed deer mouse Peromyscus leucopus
Allegheny woodrat Neotoma magister
Nutria
Nutria*Myocastor coypus*
Old World mice and rats
Black rat*Rattus rattus*
Norway rat*Rattus norvegicus*
House mouse*Mus musculus*
Opossums
Virginia opossum Didelphis virginiana
Porcupines
Porcupine Erethizon dorsatum
Rabbits and Hares
Eastern cottontail Sylvilagus floridanus
Appalachian cottontail Sylvilagus obscurus
Raccoons
Raccoon Procyon lotor
Shrews
Masked shrew Sorex cinereus
Southeastern shrew Sorex longirostris
Southern water shrew Sorex palustris punctulatus
Smoky shrew Sorex fumeus
Long-tailed shrew Sorex dispar
Southern pygmy shrew Sorex hoyi winnemana
Northern short-tailed shrew Blarina brevicauda
Least shrew Cryptotis parva
Skunks
Eastern spotted skunk Spilogale putorius
Striped skunk Mephitis mephitis
Squirrels and chipmunks
Eastern chipmunk Tamias striatus
Groundhog (aka Woodchuck) Marmota monax
Eastern gray squirrel Sciurus carolinensis
Eastern fox squirrel Sciurus niger
Delmarva fox squirrel S. n. cinereus
Red squirrel Tamiasciurus hudsonicus
Southern flying squirrel Glaucomys volans
Voles
Southern red-backed vole Clethrionomys gapperi
Meadow vole Microtus pennsylvanicus
Southern rock vole Microtus chrotorrhinus carolinensis
Woodland vole Microtus pinetorum
Mustelids
Fisher Pekania pennanti
Least weasel Mustela nivalis
American ermine Mustela richardsonii
Long-tailed weasel Neogale frenata
American mink Neogale vison
Northern river otter Lontra canadensis

</blockquote>

  *denotes introduced species

Sources:

Mammals of Maryland; Maryland Department of Natural Resources. Retrieved February 8, 2018.]
Wildlife Information; Virginia Department of Wildlife Resources. Retrieved July 4, 2020.
Mammals of West Virginia: A Field Checklist (2001); West Virginia Division of Natural Resources, Wildlife Resources Section. Retrieved February 8, 2018.]

Early European colonists who settled along the Potomac found a diversity of large and small mammals living in the dense forests nearby. Bison, elk, wolves (both gray and red) and cougars were still present at that time, but had been hunted to extirpation by the middle of the 19th century. Among the denizens of the Potomac's banks, beavers and otters met a similar fate, while small populations of American mink and American martens survived into the 20th century in some secluded areas.

There is no record of early settlers having observed marine mammals in the Potomac, but several sightings of Atlantic bottle-nosed dolphins (Tursiops truncatus) were reported during the 19th century. In July 1844, a pod of 14 adults and young was followed up the river by men in boats as high as the Aqueduct Bridge (approximately the same location occupied by Key Bridge today).

Since 2015, perhaps as a result of warmer temperatures, rising water levels in the Chesapeake Bay and improving water quality in the Potomac, unprecedented numbers of Atlantic bottle-nosed dolphins have been observed in the river. According to Dr. Janet Mann of Georgetown University's Potomac-Chesapeake Dolphin Project, more than 500 individual members of the species have been identified in the Potomac during this period.

Birds

{| class="wikitable"

! Birds of the Potomac River Basin

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Reptiles

thumb|right|[[Eastern box turtles are frequently spotted along the towpath of the C&O Canal.]]

{| class="wikitable mw-collapsible mw-collapsed"

!Turtles of the Potomac River Basin

Bog (=Muhlenberg) turtle Glyptemys (=Clemmys) 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

</blockquote>

  *denotes naturalized species

Sources:<br />

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

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

{| class="wikitable mw-collapsible mw-collapsed"

! 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

</blockquote>

Sources:<br />

http://dnr.maryland.gov/wildlife/Documents/herpchecklist.pdf<br />

A Guide to the Snakes of Virginia (Virginia Department of Game and Inland Fisheries, Wildlife Diversity Division, Special Publication No. 2.1) 2002; by Michael J Pinder (Author)

thumb|left|Five-lined skink, juvenile

{| class="wikitable mw-collapsible mw-collapsed"

! 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

</blockquote>

Sources:

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

Amphibians

{| class="wikitable mw-collapsible mw-collapsed"

! 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

</blockquote>

Sources:

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

{| class="wikitable mw-collapsible mw-collapsed"

! 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

</blockquote>

  *denotes naturalized species

Sources:

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

Notes

References

Citations

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 at Williamsport
Potomac River level at Harpers Ferry

Course

Lower Potomac River

Tidal Potomac River

History

Natural history

Human history

Hydrology

Water supply and water quality

Discharge

Legal issues

Fauna

Fish

Bowfin (Amiidae)

Catfishes (Ictaluridae)

Eels (Anguillidae)

Gars (Lepisosteidae)

Herrings (Clupeidae)

Killifishes (Fundulidae)

Pupfish (Cyprinodontidae)

Lampreys (Petromyzontidae)

Minnows (Cyprinidae)

Mudminnows (Umbridae)

Perches (Percidae)

Percopsids (Percopsidae)

Pikes (Esocidae)

Pirate perch (Aphredoderidae)

Poeciliids (Poeciliidae)

Pupfish (Cyprinodontidae)

Sculpins (Cottidae)

Silversides (Atherinopsidae)

Smelts (Osmeridae)

Snakeheads (Channidae)

Sturgeons (Acipenseridae)

Suckers (Catostomidae)

Sunfishes (Centrarchidae)

Temperate basses (Moronidae)

Trout and whitefish (Salmonidae)

Mullets (Mugilidae)

Drums (Sciaenidae)

Soles (Soleidae)

Sharks (Carcharhinidae)

Mammals

Birds

Reptiles

Amphibians

See also

Notes

References

Citations

Works cited

External links