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


Loudoun Watershed Watch Overseeing the Water Resources of Loudoun County, VA
	Human Impacts on Watersheds Some sources of pollution affect the water quality on a continuous basis such as a discharge from a sewage treatment plant. Other sources of pollution may be intermittent such as marginally operating septic tanks that overflow after heavy rainfalls when the ground is saturated with water. Some sources of pollution may flow from a single point source such as a pipe discharging gray or laundry water from a residence. Other sources may be more diffused in their impact upon a stream such as stormwater runoff.
	Urban Storm Water -- Urban streams often have little or no natural buffers next to them to filter stormwater and reduce its impacts. Runoff in urban areas has many toxins in it and is generally much warmer than that in the streams. It also enters the stream in large quantities at once.	Erosion at stormdrain discharge in Sugarland Runs
	Construction Site Runoff -- Construction projects often contribute excessive sediments to streams due to the removal of vegetation from drainage channels and streamsides that reduce bank stability. Altering natural stream channels causes the stream to find a new equilibrium that involves stream down cutting and bank erosion. Excessive sediments will cause sand and gravel bars to form in the stream channel and increased bottom scouring that destroys habitat for aquatic life.	Construction along Dutchman's Creek
	Failing Septic Systems - Septic systems that are not properly maintained will fail and result in raw human and household waste seeping into streams. These wastes contain nutrients that will over-stimulate growth of algae, aquatic plants, and sewage-loving aquatic insects such as black flies. Bacterial digestion of large amounts of organic wastes will deplete the dissolved oxygen in streams and make conditions unfit to support a diverse population of organisms. The wastes may also contain toxic chemicals, many disease-causing microorganisms, and viruses.
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