SECTION 3 - Protecting and Enhancing Our Environment:
III. Water Quality

Fairfax County has over 900 miles of perennial streams and many intermittent streams, ponds and lakes. The County also has many underground aquifers (groundwater). These provide drinking water, recreation and enjoyment for humans and habitat and food for a myriad of animals and organisms.

Everyone in Fairfax County lives in the Potomac watershed, which in turn is part of the larger Chesapeake Bay watershed. All of the 30 major streams and their tributaries drain into the Potomac River, which empties into the Chesapeake Bay. Both the Occoquan Reservoir and the mainstem Potomac River are the drinking water supply for most Fairfax County residents. A small percentage of the county's residents get their drinking water from wells that tap into groundwater.

Many stream banks are lined with trees and vegetation. Wetlands, beaver dams and ponds contain an abundance of wildlife and provide access to natural habitats and recreational opportunities for many Fairfax citizens. One-third of the land in the Fairfax County Park system is in stream valley parks.

Water quality depends on many factors, but none has more impact than impervious surface cover. Over 36 percent of the County was "vacant" in 1975 whereas only 11.5 percent was vacant in 2000. This means that 62 square miles of asphalt, rooftops, driveways, parking lots, and other impervious surfaces now cover the county. This is roughly the area of Washington DC. Fluids from leaking cars, fertilizers, herbicides, pesticides, sediments, trash and litter are washed off these hard surfaces and into our waterways. Also with less infiltration, our streams are being asked to carry an increased quantity of water that exacerbates stream bank erosion.

What is the status of our waters?

• Only a few streams, such as those in E. C. Lawrence Park, remain undisturbed and are excellent examples of healthy streams.
• Seventeen (17) streams in Fairfax County are "impaired" because of excess pollutants. The Chesapeake Bay itself has "impaired waters," according to the U.S. Environmental Protection Agency. It is estimated that Virginians must spend approximately $6.1 billion by 2010 to restore the health of the Bay. In addition, the Virginia Department of Environmental Quality has ordered clean-up through the Total Maximum Daily Load (TMDL) requirement of the Clean Water Act.
• Poor land use planning in previous decades, inadequate enforcement erosion and sediment control laws, and inadequate storm water management in past years have significantly exacerbated pollution and erosion.
• Most of Fairfax County's streams are polluted and degraded, largely from poorly managed storm water runoff. Storm water runoff transports excess nutrients, fertilizers, herbicides, pesticides, sedimentation, pollution, chemicals, and bacteria into streams from poorly managed construction sites, disturbed lands, roads, parking lots, animal and human waste, leaking sewer pipes, and failing septic systems.
• The number one threat to the County's streams is the increase in impervious surfaces and accompanying tree loss. Impervious surfaces replace land and vegetative cover that absorbed water during precipitation events. With the increase in impervious surface and loss of vegetation, there is a concurrent increase in the amount and speed of water running off the land during storm events and carrying pollutants to nearby streams.
• Sediment, nutrients (fertilizers), pathogens (animal waste), toxics (oil, chemicals), and litter are the major water pollutants in Fairfax County.
• Most streams have increased storm water runoff flows that exceed the capacity of their channels. This has created an ongoing erosion cycle that includes eroding stream banks, heavy sediment loads, and sedimented stream bottoms. This erosion cycle persists for years, if not decades, until the stream channel widens to accommodate the flow. Silted stream bottoms and collapsing stream banks are all-to common throughout our county.
• Streambank erosion from increased storm water runoff has put enormous sediment deposition into ponds and lakes, which can require frequent maintenance and dredging to maintain depth.
• During summer storms, heated impervious surfaces raise the temperature of storm water runoff entering streams and other waters, which can damage or destroy aquatic life and habitat.
• Excess nutrients in stormwater runoff encourage excessive algal growth. When the algae decomposes it uses oxygen, causing a lack of oxygen in the water,needed to support aquatic life. These problems reduce plant and animal life in and near the streams.
  

The Board's Environmental Plan:

• Protect those streams whose waters are still of relatively high quality from becoming impaired with pollutants. Protection and prevention are less expensive and easier than restoration.
• Consider watershed protection when reviewing and deciding all land use actions.
• Implement the new Watershed Management Plans and Stream Protection Strategies as they are created. Pursue a dedicated source of funding for this effort. Without some ongoing budget commitment, this effort will languish.
• Grant no BMP waivers without storm water mitigation being in place or constructed.
• Allow and encourage better site design practices that protect our streams and other natural resources.
• Ensure strict enforcement of erosion and sediment control laws during construction.
• Slow down and filter pollutants from runoff by encouraging the establishment and maintenance of vegetative filters and buffers.
• Stabilize and restore streams using sound scientific principles (applied fluvial geomorphology) that work in concert with natural tendencies, mimic natural systems, and use environmentally friendly techniques such as soil bioengineering.
• Implement the recommendations in the March 2003 report on "The Role of Regional Ponds in Fairfax County's Watershed Management."
• Implement the recommendations of the New Millenium Occoquan Watershed Task Force (December 2002) to protect the County's drinking water supply in the Occoquan Reservoir.
• Monitor the Health Department's inspection of septic systems and their requirement for septic system pump-out and maintenance on a regular basis, for example, every five years.