The land corridors that border and include rivers and streams comprise the
county’s largest natural ecosystem, consisting of nearly 500 miles of perennial streams. These areas are known as riparian corridors and the land adjacent to the streams are known as floodplains.
Where floodplains and stream corridors have been preserved or reestablished to their natural condition, they help filter pollution from runoff, provide shade that keeps stream water cool, detain flood waters and reduce their velocities, and provide food and habitat for fish and wildlife. The county’s river and stream corridors include wetlands, riparian forests, steep slopes, and many of the county’s important historic and archaeological sites. They also provide many scenic, recreation, and educational opportunities.
Land Uses in Floodplains
The decision to maintain the natural benefits of floodplains, as well the decision to strive to prevent public and private flood losses, require that certain land uses in the floodplain be restricted or prohibited by county ordinances and policies. In addition, an engineering analysis of the impacts of “allowed” uses in the floodplain is necessary to ensure that impacts on neighboring properties and the natural buffer are minimized. In order to provide for this analysis, floodplain study and floodplain alteration applications associated with development are reviewed for consistency with the county’s requirements and FEMA's National Flood Insurance Program (NFIP).
The Loudoun County floodplain management program is basically a decision-making process that is implemented to determine the most appropriate land uses within the floodplains. This decision-making process is based upon a balance of the preservation of natural and beneficial floodplain functions, minimizing risk to human life and risk of property damage, and economic development where appropriate and necessary. Streams that drain 100 acres or more include regulatory floodplain areas which are important to manage wisely in order to adequately address these factors.
Because of the implementation of Loudoun County’s floodplain management program, there are very few properties that experience recurring flood damage. New residential and commercial buildings must be located outside of the major (FEMA) floodplain limits throughout the county. Subsequently, the vast majority of residents are not required to purchase flood insurance; and, those required to obtain flood insurance are able to do so at reduced premiums. Moreover, these program basics help to maintain the aforementioned environmentally beneficial buffering effect and aesthetics of the floodplain.
For questions or more information about floodplains in Loudoun County, please contact the Department of Building and Development Floodplain Help Line at 703-737-8746.