Alert:
Lake Accotink Park has long served as a local treasure for residents of Fairfax County, Virginia. With a 55-acre lake as its centerpiece, the park offers recreational opportunities and natural vistas where people come to escape from everyday life. But it is modern life itself - with its dense subdivisions, reliance on highways and parking lots, and other impacts on the environment - that is changing the delicate balance of the lake and the watershed in which it lays. These changes happen in ways that we do not often consider. This article offers information about the impact of development and modern living as it affects the Accotink Creek Watershed - and ultimately the larger world to which it connects.
The Accotink Creek Watershed encompasses 51 square miles. Of this are, 30 square miles drain into Lake Accotink. This causes the lake to bear the brunt of runoff that occurs with every rainfall. All the rooftops, parking lots and streets in the Accotink Creek Watershed prevent the rain from seeping into the ground. Instead, it flows along roads, parking lots, and other impervious surfaces and enters storm drains that pipe the water to nearby streams, and ultimately the lake itself. Storm runoff includes trash, debris, dirt and sand, as well as toxic chemicals that can contaminate fish, birds and animals. In addition, consider that pavement heats up faster than natural turf (as anyone who has walked barefoot outside knows). The higher temperature of rainwater traveling across pavement abruptly raises water temperatures in lakes and streams-causing stress to fish and other species sensitive to temperature changes.
Most people understand the threats to the ecosystem caused by toxic chemicals. Less understood is the impact of the runoff itself as it rushes into lakes and streams.
Anyone who has experienced flooding knows the power and speed of moving water. The runoff water's increased mass and speed cause the stream channel banks and beds to swiftly erode. This erosion ends up in the streams and adds to the sediment that the streams are already sending into the lake.
The problem becomes more severe in areas where natural grass and woodlands have been replaced by concrete and asphalt. Such "impervious surfaces" can increase the amount of runoff by as much as 16 times. In the case of Lake Accotink, its location in an urbanized area means that as many as 10,000 tons of sediment enter the lake each year - which is equivalent to a school bus full of sediment dumping its load into the lake every day!
The effects of siltation on the lake are dramatic. When Lake Accotink was first formed (in 1918 as a reservoir for Camp A. A. Humphreys, now Fort Belvoir), the lake covered 110 acres and was 23 feet deep. Today, the lake is only about 55 acres and shallow enough to walk across. If nothing is done, the huge amount of sediment and dirt continually entering the lake will gradually fill it in. But rather than allow Lake Accotink to disappear in 30 years, Fairfax County is investing in this natural resource by dredging the lake of its sediment - a project which began in 2004 at a cost of $6.1 million. It will take nothing less than an investment on this scale to remove the sediment produced since the last dredging in 1986.
Through a Wider Lens
The Accotink Creek Watershed is fourth largest watershed in Fairfax County, and its impact extends far beyond Fairfax County. Water and materials entering tributary streams throughout the watershed flow to Accotink Creek, which flows into the Potomac River, which flows into the Chesapeake Bay. So Lake Accotink acts as a catch basin for sediment that would otherwise enter the bay. Seen in this context, stream restoration projects undertaken in the Accotink Creek Watershed can make a positive impact on the health of the Chesapeake Bay.
Similarly, restrictions on development along stream corridors in this area also serve to protect the health of the bay. Recent changes in legislation have expanded local stream protections in order to create buffer zones, or vegetated areas, around most waterways leading to the bay. Such measures are essential to stop the loss of natural filters for pollutants and slow down storm water runoff. Loss of stream buffer areas leads to stream bank and channel erosion, increased pollution and habitat destruction. Properties located where habitat is in decline often become less-desirable real estate. Thus, owners of property located along streams and waterways have a vested interest in supporting legislation and community practices that protect local waterways and the watershed. Residents thinking about putting additions on their homes or building small structures in their yards should first find out if their property lies within a protected area. And all residents can do their part - from joining community-based groups performing work such as planting projects and stream restoration projects, to contributing financial support to environmental organizations or advocating for watershed protections.
With education and conscious effort, Fairfax County residents can help ensure that that the Accotink Creek Watershed plays its critical role in protecting both the Chesapeake Bay and our quality of life.
Save the World From Home!
Groups that Need your Help:
Important Stormwater Management Information Available for Presentation.
Fairfax County is working on a project with residents to enhance the current stormwater management program to improve streams, prevent flooding and erosion and raise awareness about stormwater issues. County representatives are available to speak to organizations, associations and groups about this project and the possible funding options to finance the improvements. Request a county representative to speak to your group by contacting the Fairfax County Stormwater Planning Division at 703-324-5821 via e-mail.
What is the Upper Accotink Creek Watershed Program?
The Upper Accotink Creek Watershed Education Program focuses on promoting environmental stewardship among the citizens of Fairfax County in general, and the Upper Accotink Creek Watershed in particular. Through a program of watershed education and awareness, the meaning and importance of watersheds, how they work, and how they are impaired will be brought to the public’s attention, along with what can be done to improve the Accotink Creek Watershed and other county watersheds.
Why is such a program needed?
Lake Accotink has lost 20 surface acres in the past 15 years. This has been caused by sedimentation. Many people believe that sedimentation is only a result of failure to control runoff from construction sites; however, the sedimentation that is shrinking Lake Accotink is due to the large amount of impervious surfaces (parking lots, roads, roofs) in already built and stabilized areas. A temporary solution to this problem is the upcoming dredging of the lake. While this is a stopgap for preserving the recreational value of Lake Accotink, it does not address the causes that led to the need to dredge in the first place.
What is causing so much sedimentation in Lake Accotink?
Fairfax County is already a highly suburbanized area. The Upper Accotink Creek Watershed has been developed for many years now. When it rains, all the water in the watershed eventually ends up in Lake Accotink. Instead of flowing across the land and being absorbed by the ground, water ends up rushing over those impervious surfaces. The water speeds up so much that by the time it reaches the streams and creeks, it is moving very quickly. It scours the sides, or banks, of the streams and creeks. Such a large amount of water moving rapidly after a storm is referred to as a storm surge. This sediment then gets deposited in Lake Accotink.
These links provide more in depth information:
Watersheds: The Meeting Place of Life
Watershed and Accotink Creek Watershed Facts
Conservation Tips: How can I improve the water quality at Lake Accotink?
Storm water flow and impervious surfaces
Friends of Accotink Creek (www.accotink.org/AboutFACC.htm) is a volunteer organization restoring Accotink Creek to enhance enjoyment of biking, fishing, jogging, walking and bird watching along a major portion of the Cross County Trail.
Accotink Creek runs through one of the finest wildlife corridors in Fairfax County. Accotink Creek passes through Eakin, Wakefield, Lake Accotink and Accotink Stream Valley Parks; Ft. Belvoir and the Accotink Bay National Wildlife Refuge, then drains into the Potomac River, affecting waters of Chesapeake Bay.
Friends of Accotink Creek are committed to protecting, promoting and restoring the water quality, natural habitat, and ecological well-being of the Accotink Creek watershed. Their goals are to:
The Invasive Management Area (IMA) program is a volunteer-led pilot project in partnership between the Fairfax County Park Authority and Northern Virginia Soil and Water Conservation District designed to reduce invasive plants on our parklands. Friends of Accotink Creek has volunteered to coordinate IMA invasive species removal at Lake Accotink Park, targeting a large area of kudzu in a wetlands area of the park.
The kudzu was transplanted to North America with the intention of using it to anchor steep banks of soil and thereby prevent erosion. The plant has become a rampant weed in parts of the southeastern United States, however, since it readily spreads over trees and shrubs as well as exposed soil. The kudzu is a fast-growing, woody, somewhat hairy vine that may grow to a length of 18 m (60 feet) in one season. It has large leaves, long racemes with late-blooming reddish purple flowers, and flat, hairy seed pods. The plant is native to China and Japan, where it was long grown for its edible, starchy roots and for a fiber made from its stems.