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Potomac River

Upper part of the Potomac River
Upper part of the Potomac River

The Potomac River is a tributary of the Chesapeake Bay, located along the mid-Atlantic coast of the United States (USA). The river is approximately 413 statute miles (665 km) long, with a drainage area of about 14,700 square miles (38,000 km²). In terms of area, this makes the Potomac River the fourth largest river along the Atlantic coast of the USA and the 21st largest in the USA as a whole.



The Potomac River springs from southwest Maryland (MD). The river then forms part of the borders between MD and Washington, DC (the District of Columbia) on the left bank and the State of West Virginia (WV) and the Commonwealth of Virginia (VA) on the right bank. Up to its right bank, the entire Potomac River is considered part of MD, with the exception of a small tidal portion within DC. The river pours out 13000 gallons of water a minute.

Great Falls of the Potomac
Great Falls of the Potomac

About 300 miles (483 km) from the source, the Potomac River's estuarine portion commences. About 11 km² of water enters the estuary each year (250 m³/s) at the fall line at Little Falls. Fall line flow is quite variable across months and years, highest during the spring freshet and lowest in late summer (in the absence of hurricanes or major storms).

The river's source is 396 m above sea level and it drops to 61 m at Morgantown, West Virginia. Once the Potomac drops from the Piedmont to the Coastal Plain, tides further influence the river as it passes through DC 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, MD, and Smith Point, VA, before merging into Chesapeake Bay.

Major Potomac tributaries include the Shenandoah River (WV and VA) and the Monocacy River (MD) above the fall-line and the Anacostia River (DC and MD) and Occoquan River (VA) below the fall-line.

Over 5 million people live within the Potomac watershed, where precipitation provides the equivalent of over 8 m³ (more than 2100 gallons) of water per person per year.


The name Potomac is a European spelling of an Algonquin name which supposedly means 'river of swans.' Other accounts say the name means 'place where people trade' or 'the place to which tribute is brought' and that the name translated as 'river of swans' was another word, 'Cohongorooton.' The spelling of the name has been simplified over the years from Patawomeke to Patowmack in the 18th century and now Potomac.

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, USA's first president, was born in, surveyed and spent most of his life within the Potomac basin. All of DC, the nation's capital city, also lies within the watershed. The 1859 siege of Harper's Ferry along the river's right bank was a precursor to numerous epic battles of the American Civil War in and around the Potomac and its tributaries.

The Patowmack Canal was intended by George Washington to connect the tidewater near Georgetown with Cumberland, MD. Started in 1785, it was not completed until 1802. Financial troubles closed the canal in 1830. The C&O Canal operated along the banks of the Potomac in Maryland from 1850 to 1924 and also connected Cumberland to Washington, DC. This allowed freight to be transported around the rapids known as Great Falls of the Potomac , as well as many other, smaller rapids.

With increasing mining and agriculture upstream and urban sewage and runoff downstream, water quality in 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 sewage pollution and restore the beauty and ecology of this historic river. By the end of the 20th century, there was notable success, 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.

See also

External links and references

Last updated: 08-07-2005 21:28:03
Last updated: 08-30-2005 19:01:45