Dyke Marsh
"...An area of irreplaceable wetlands near the Nation's Capital which is valuable for the production and preservation of wildlife." - PL 86-41
Located on the West Bank of the Potomac River some 95 miles from the Chesapeake Bay, Dyke Marsh consists of approximately 380 acres of tidal marsh, floodplain, and swamp forest. Dyke Marsh, which is believed to have formed 5,000 - 7,000 years ago, is unique in that it represents the largest remaining piece of freshwater tidal wetlands in the Washington Metropolitan area.
Managed by the-National Park Service as a part of the George Washington Memorial Parkway, Dyke Marsh not only provides habitat for a diverse array of plants and animals, it also offers an ideal setting for a variety of recreational activities. The trail, which leads visitors into the marsh, known as the "haul road," is a favorite of area birdwatchers and is also utilized by hikers, photographers, and nature lovers. In addition, the waters in and around the marsh are popular fishing areas for people and animals and those that explore the marsh by canoe are rewarded with up-close encounters with the resident wildlife.
What's in a name?
Dyke Marsh was indeed "diked" at one time. In the early 1800's earthen walls were built around the perimeter of the marsh in order to create more "fast land;" land not inundated by the high tides. These areas would then be used to graze livestock or grow crops.
Animals of the marsh.
Dyke Marsh provides habitat which supports a diverse collection of animals. Evidence of beaver activity is visible along the haul road and muskrat have been known to live in the marsh as well. At dusk, little brown bats and red fox begin their nightly forays. Other mammal species observed in the marsh include: cottontail rabbit, gray squirrel, shrews and field mice.
Several species of reptiles and amphibians also inhabit Dyke Marsh. Bullfrogs and leopard frogs must be on the lookout for northern water snakes and snapping turtles. During the summer months painted turtles can be seen on logs absorbing the sun's warmth and a box turtle might be seen roaming the floodplain in search of food.
"O-KA-LEEEE!"
Perhaps the most common sound heard in Dyke Marsh is the call of the redwinged Blackbird. Commonly associated with wetlands, the redwinged blackbird nests among the cattails and feeds on insects and seeds. The redwinged blackbird is but one of nearly 300 species of birds observed in Dyke Marsh, one of the premier birdwatching spots in the Metropolitan Washington area.
Plants, plants, and more plants.
To date, more than 360 species of plants have been recorded in Dyke Marsh. The dominant species of the marsh itself is the narrow-leafed cattail, which typically develops its characteristic flower spike by June. Other species associated with the tidal marsh include: arrowhead (a.k.a. duck potato), a plant whose starchy tubers are favored by waterfowl; arrow arum, a distinctive plant with large triangular leaf blades; pickerelweed; sweetflag; spatter-pond lily; and northern wild rice, the grains of which are enjoyed by redwinged blackbirds, waterfowl, and people.
The human factor.
Today, Dyke Marsh is much different than it was just 50 years ago. It is estimated that Dyke Marsh once consisted of 650 acres; dredging done during the 1950's and 60's led to the current size and configuration of the marsh. Impacts of this dredging are still felt today - shoreline erosion is very noticeable along sections of the haul road.
An exotic dilemma.
Another result of human disturbance in Dyke Marsh has been the introduction of several exotic, or non-native, plant species. Exotic species are very opportunistic, growing in disturbed areas and oftentimes outcompeting beneficial native species.
Several exotic vines are smothering portions of the floodplain forest: porcelain-berry, a native of northeast Asia; Japanese honeysuckle; and Asiatic bittersweet. The marsh itself is not immune to exotics, yellow iris and the common reed are present and efforts are being made to prevent the introduction of purple loosestrife.
A fragile habitat.
Today, armed with a greater understanding of the importance of wetland ecosystems, we can take steps to protect the fragile habitat that is Dyke Marsh. You can help us in our mission, and ensure that Dyke Marsh will be enjoyed by future generations, by observing the following guidelines:
Environmental Assessment for a Raised boardwalk and improvements to wildlife viewing areas at Dyke Marsh.