Dyke Marsh is a freshwater

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The p ...

and

wildlife preserve A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, or features of geological or ...

located on the west bank of the

Potomac River The Potomac River () drains the Mid-Atlantic United States, flowing from the Potomac Highlands into Chesapeake Bay. It is long,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map. Retrieved Augu ...

south of

Alexandria Alexandria ( or ; ar, ٱلْإِسْكَنْدَرِيَّةُ ; grc-gre, Αλεξάνδρεια, Alexándria) is the second largest city in Egypt, and the largest city on the Mediterranean coast. Founded in by Alexander the Great, Alexandri ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

between Old Town Alexandria and

Mount Vernon Mount Vernon is an American landmark and former plantation of Founding Father, commander of the Continental Army in the Revolutionary War, and the first president of the United States George Washington and his wife, Martha. The estate is on ...

. Dyke Marsh consists of about of

tidal marsh A tidal marsh (also known as a type of "tidal wetland") is a marsh found along rivers, coasts and estuaries which floods and drains by the tidal movement of the adjacent estuary, sea or ocean. Tidal marshes are commonly zoned into lower marshes ( ...

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

, and swamp forest. It formed 5,000 to 7,000 years ago. With a total size of 485 acres, Dyke Marsh is one of the largest remaining pieces of freshwater tidal wetlands left in the Baltimore-Washington Metropolitan Area. The marsh is managed by the

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propert ...

as part of the

George Washington Memorial Parkway The George Washington Memorial Parkway, colloquially the G.W. Parkway, is a parkway that runs along the south bank of the Potomac River from Mount Vernon, Virginia, northwest to McLean, Virginia, and is maintained by the National Park Service ( ...

. Dyke Marsh contains a wide array of plant and animal life. "Haul Road" is a trail that leads visitors into the marsh. It is frequented by area birdwatchers. Dyke Marsh is located off the

at the Belle Haven Marina exit. Here the fresh water of the upper Potomac mixes with the salt water of the lower Potomac. The fresh water tends to float above the tidal salt water producing a tidal freshwater marsh.

Name

Dyke Marsh got its name because it was within a

dike Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes ...

at one point. Earthen walls were built around the perimeter of the marsh in the 19th century to create more "fast land," land not inundated by tides. This land was used for farming purposes, mainly to graze livestock or to grow crops. Dyke Marsh map

One of the oldest photographs of Dyke Marsh is a ''circa'' 1909 picture postcard created for the Alexandria-Mt. Vernon trolley line (whose light rail tracks were replaced by the George Washington Memorial Parkway in 1932.) The photograph is labelled: ''The "Dyke," a favorite resort for fishermen and hunters on the line of the Mt. Vernon Railroad, near Alexandria, Va''.

Wildlife

Dyke Marsh has an abundance of wildlife. Evidence of a beaver population is visible along the "Haul Road" and muskrat have been spotted numerous times.

Little brown bat The little brown bat or little brown myotis (''Myotis lucifugus'') is an endangered species of mouse-eared microbat found in North America. It has a small body size and glossy brown fur. It is similar in appearance to several other mouse-ea ...

s and red fox can be seen at night.

Cottontail rabbit Cottontail rabbits are the leporid species in the genus ''Sylvilagus'', found in the Americas. Most ''Sylvilagus'' species have stub tails with white undersides that show when they retreat, giving them their characteristic name. However, this ...

gray squirrel Gray squirrel or grey squirrel may refer to several species of squirrel indigenous to North America: *The eastern gray squirrel (''Sciurus carolinensis''), from the eastern United States and southeastern Canada; introduced into the United Kingdom, I ...

shrews Shrews (family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to different ...

, and field mice (the

vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...

) can also be found in and around the marsh. The most obvious inhabitant of Dyke Marsh is the

red-winged blackbird The red-winged blackbird (''Agelaius phoeniceus'') is a passerine bird of the family Icteridae found in most of North America and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and G ...

, with its distinct call. The red-winged blackbird nests among the

cattails ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in ...

and feeds on insects and seeds. Nearly 300 species of birds have been seen in Dyke Marsh. It is known as one of the best

birdwatching Birdwatching, or birding, is the observing of birds, either as a recreational activity or as a form of citizen science. A birdwatcher may observe by using their naked eye, by using a visual enhancement device like binoculars or a telescope, by ...

sites in the

Washington Metropolitan Area The Washington metropolitan area, also commonly referred to as the National Capital Region, is the metropolitan area centered on Washington, D.C. The metropolitan area includes all of Washington, D.C. and parts of the states of Maryland, Virgi ...

. The lower Potomac is a natural migration route, especially for water birds. In 2014 a beetle species, ''Pterostichus sculptus,'' new to Virginia was discovered at Dyke Marsh.

Plants

More than 360 species of plants have been found at Dyke Marsh. The narrow-leafed

cattail ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in ...

is the dominant species in the area. It normally develops its characteristic flower spike by June. Many other species of plant occupy the marsh including several types of ''

Sagittaria ''Sagittaria'' is a genus of about 303. Sagittaria Linnaeus
''

northern wild rice. The rice attracts animals such as the red-winged blackbird and

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...

Changes

Dyke Marsh is much different than it used to be. It is estimated that the marsh once consisted of . In the 1950s and 1960s, dredging took place, which reduced it to its current size and configuration. Shoreline

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

is noticeable along the Haul Road, showing that the dredging is still making an impact. Human influences have also led to the introduction of several types of exotic, or non-native, plants to the marsh. These plants are very opportunistic and often outcompete beneficial native species of plants. Exotic vines, such as the Asian porcelain berry,

Japanese honeysuckle ''Lonicera japonica'', known as Japanese honeysuckle and golden-and-silver honeysuckle, is a species of honeysuckle native to eastern Asia. It is often grown as an ornamental plant, but has become an invasive species in a number of countries. Jap ...

, and Asiatic bittersweet have begun smothering parts of the floodplain forest. Yellow iris and the

common reed ''Phragmites australis'', known as the common reed, is a species of plant. It is a broadly distributed wetland grass that can grow up to tall. Description ''Phragmites australis'' commonly forms extensive stands (known as reed beds), which may ...

are exotic plants that now inhabit the actual marsh. Efforts are being made to prevent the introduction of the

purple loosestrife ''Lythrum salicaria'' or purple loosestrifeFlora of NW Europe''Lythrum salicaria'' is a flowering plant belonging to the family Lythraceae. It should not be confused with other plants sharing the name loosestrife that are members of the family Pr ...

Uses

Dyke Marsh is just east of the

and the

Mount Vernon Trail The Mount Vernon Trail (MVT) is a long shared use path that travels along the George Washington Memorial Parkway in Northern Virginia between Rosslyn and George Washington's home at Mount Vernon. The trail connects the easternmost portions of ...

. Thousands of bicyclists, walkers, and runners go through Dyke Marsh on a weekly basis on the Mount Vernon Trail. Just off of the trail, there is a sitting area on a boardwalk over the marsh. The interior path is J-shaped and goes south from the marina entrance and then turns east onto a peninsula. Birdwatchers, animal lovers, and nature enthusiasts often visit the sitting area in an effort to catch a glimpse of what Dyke Marsh has to offer. Visitors also come at night to watch the fireflies in the marsh and trees.

References

External links

Friends of Dyke Marsh
- National Park Service
Jackson Miles Abbott Papers, 1929, 1960–1985, and undated
which features detailed information on the founding of Dyke Marsh from the

Smithsonian Institution Archives Smithsonian Libraries and Archives is an institutional archives and library system comprising 21 branch libraries serving the various Smithsonian Institution museums and research centers. The Libraries and Archives serve Smithsonian Institution ...

{{authority control Protected areas of Alexandria, Virginia Protected areas of Fairfax County, Virginia Marshes of Virginia Potomac River watershed George Washington Memorial Parkway Landforms of Fairfax County, Virginia