Loudoun Watershed Watch - Overseeing the Water Resources of Loudoun County, VA


Loudoun Watershed Watch Overseeing the Water Resources of Loudoun County, VA
	Impervious Surfaces In the late 90's a study by George Washington University's Environmental Indicators program showed that over 18 acres of Loudoun County's natural landscape were being converted to buildings, roads, and manicured lawns each day. These rooftops, driveways, roads, and parking lots are a major cause of the change in many of Loudoun's' streams.
	Development -- A typical residential subdivision in eastern Loudoun has 25% to 28% impervious surface. Studies have demonstrated that as little as 10% impervious surfaces in a watershed can have negative effects on water quality. Impervious surfaces of 25% produce possibly irreversible degradation in the local stream as well as the entire downstream watershed.	Development along Beaverdam Run
	Erosion -- Streams are degraded because of substantially higher peak water flows during storm events. The increased flows generate extra energy that the stream accommodates by down-cutting the stream bottom and widening the channel. Both the down cutting and widening cause stream banks to erode which puts sediments into the water. These unstable conditions will last long after development is completed. Reestablishing a stable stream channel typically can takes decades.	Erosion in Cardinal Glen drainage
	Pollutants -- Stormwater runoff from urban/suburban areas, industrial parks, and roadways also contain a variety of pollutants including oil, grease, heavy metal, and pesticides. Without forested floodplains and vegetative buffer zones along streams, these pollutants are not absorbed into the ground and converted by bacteria. Instead they flow directly into the waterways where they are toxic to aquatic organisms and other organisms in the stream food chain.	Drainage pipe to Sugarland Run
info@loudounwatershedwatch.org Copyright © 2011 Loudoun Watershed Watch