Prince William Conservation Alliance
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Clean Water Act Comparative Ranking for Prince William
Occoquan Interactive Watershed
Fairfax County Water Authority
Fairfax County's Occoquan Watershed - Celebrating the 20th Anniversary of the Downzoning
Occoquan Watershed: What It Is & What's In It?
presentation to Prince William Conservation Alliance on January 30, 2003
Occoquan Watershed 1995 Land Use Survey Map
Occoquan Reservoir Shoreline Protection
Occoquan Watershed Monitoring Laboratory (OWML)
Upper Occoquan Sewage Authority - Indirect Potable Water Reuse

Virginia Administrative Code, State Water Control Board

Chapter 410 - Occoquan Policy

Evaluation of Impervious Surface Estimates
in a Rapidly Urbanizing Watershed

The Fairfax County Water Service Authority's Occoquan Reservoir Easement - Background & Other Relevant Information

What is an easement?

  • An easement is a right of way giving individuals other than the owner permission to use a property for a specific purpose. Utilities often have easements that allow them to run pipes, electric lines, etc., through private property. Utilities, such as Dominion Power and the Fairfax Water Service Authority manage the easement to maintain the dependability of the intended public use.

How do I know if there is an easement on my property?

  • Easement information is included in the individual property deeds.
  • The Fairfax County Water Service Authority (WSA) has an easement around the perimeter of the Occoquan Reservoir. This easement covers lands adjacent to the Reservoir that are between the elevations of about 120 ft msl (mean sea level) and 130 ft msl.

Purpose of the Water Service Authority Easement

  • The Occoquan Reservoir is a major Northern Virginia drinking water source.
  • The WSA Easement Policy helps protect the Occoquan River water supply from inappropriate activities within the existing water supply easement.

Why is this important?

  • About 172,000 Prince William residents, 80% of public water users, depend on the Occoquan Reservoir for clean drinking water. The remaining 20% of Prince William’s public water users get clean drinking water from a combination of the Occoquan Reservoir and the Potomac River.

  • Land use changes are the primary cause of degradation of the Occoquan Reservoir.

  • Shoreline protection and buffers containing native woody vegetation contribute significantly to shoreline protection, good water quality conditions and habitat integrity.

  • Nearly 40% of Prince William lands drain directly to the Occoquan Reservoir and 38% of the watershed population lives in Prince William.

What is land conservation along the Occoquan Reservoir

Occoquan Reservoir showing Fairfax County to the North and Prince William County to the south.

  • In the late 1950’s, Fairfax County conserved 5,000 acres along the shore of the Bull Run-Occoquan River stream valley. This continuous strip of parkland, managed by the Northern Virginia Regional Park Authority, is a valuable conservation area that protects wetlands, forests and the shoreline of the Occoquan Reservoir.

  • Prince William has developed the southern side of the Occoquan Reservoir. Lake Ridge Park remains the single public access point. Demands from competing public uses now threaten this Park with overuse.

Fairfax County - Occoquan Reservoir Watershed Downzoning
  • In the early 1980’s, Fairfax County downzoned  41,000 acres of land to protect the Occoquan Reservoir. The downzoning limited the number of houses that could be built required stringent treatment of stormwater runoff.
  • Fairfax County designated their entire 64,500-acre portion of the Occoquan Reservoir's watershed as the Water Supply Overlay Protection District (WSPOD). Any development in this area that requires either a site plan or a subdivision plan must comply with rigorous water quality performance standards.

Why are vegetated buffers important?

Vegetated buffer areas are natural barriers of existing or established perennial vegetation. These areas effectively separate incompatible land uses and activities, and protect waterways from nonpoint source pollution. Vegetated buffer areas have many conservation values including:

  • Prevent shoreline erosion.
  • Provide shade, which helps reduce alga growth and keeps summer water temperatures cooler. Cooler water holds more oxygen, which is good for aquatic life. Cooler water increases the stream’s capacity to assimilate pollution.
  • Slow down stormwater runoff. This helps filter out sediments and other pollution from upland land uses, and reduces turbidity.
  • Provide habitat for fish and other aquatic life. Adjacent and overhanging vegetation helps create a diversity of habitats, which supports a diversity of aquatic life.
  • Provide corridors that are needed for wildlife routes within and between habitats. Many species of wildlife thrive in vegetated corridors along water bodies.
  • Preserve and enhance aquatic environments for hiking, camping, fishing and boating.
  • Provide cost effective protection to human land uses from flooding and shoreline erosion problems.
  • Scenic qualities provide visual contrast to more intensive suburban land uses and increase property values.


  • Litter is a big problem in Prince William County. Every year over 17,000 volunteers help clean up trash along Prince William roads and creeks. Leesylvania State Park volunteers clear about 2 tons of trash from the Neabsco Creek watershed every year. In addition, Public Works clean-up crews pick up over 1.5 tons of litter every week.

  • Most litter (one type of nonpoint source pollution) travels a long way before it reaches the Occoquan Reservoir. Most of the trash in the Occoquan Reservoir is coming from throughout the watershed area. Litter in Gainesville travels across land and through storm drains to nearby creeks. Once the trash reaches the closest creek, it travels downstream until it is either cleaned up, reaches a barrier or reaches the Occoquan Reservoir.

How can you help cluen up Prince William's Occoquan Reservoir watershed?

  • Illegal dump sites or roadways in particular need of litter control – Call Prince William County Environmental Services at 703.792.6666 and they will schedule a crew to clean up the area.

  • Community Clean-ups – Call Prince William Clean Community Council at 703.792.6272 to find out about groups conducting clean ups near your neighborhood.

  • Adopt-a-Stream – Call Prince William Soil and Water Conservation District at 703.594.3621 to find out how your family can adopt a stream.

  • Storm Drain Identification – Help community members understand that storm drains connect to the closest creek, not the sewage treatment system. Call the Prince William Conservation Alliance at 703.367.0069 to find out how you can initiate a community project to mark neighborhood storm drains.