When it rains or snows, the amount
of water that is absorbed back into the environment varies largely on
whether the land is paved or natural. Rain and snow on natural or
undeveloped land gradually infiltrates into the soil, replenishing
groundwater supplies and slowly discharging excess runoff to local
creeks. In contrast, as we pave roads and sidewalks, construct buildings
or add other impervious surfaces, the amount of water that can be
naturally absorbed after a rain or snow event is reduced drastically.
Water that cannot infiltrate into the surrounding environment is called
water runoff or stormwater
runoff. In order to prevent our communities from flooding, stormwater
runoff is diverted into storm
drains and carried to the nearest stream. Ultimately, this runoff
makes its way to the Chesapeake Bay through our numerous watersheds.
Because impervious surfaces
prevent stormwater from infiltrating into the soil, runoff increases in
quantity and speed, causing environmentally harmful, and potentially
dangerous, bank erosion in streams. As stormwater runoff flows over
pavement and yard areas, it picks up pollutants like nutrients, oils,
sediment, trash, heavy metals and chemicals that are left on our streets
and walkways. Eventually, all those pollutants make their way down
through our watersheds to the
Potomac River and the Chesapeake Bay.
In order to help prevent bank erosion and pollution in our watersheds, engineers and biologists have worked together to develop “Best Management Practices,” also called BMPs, to accommodate stormwater runoff while minimizing environmental impacts. Best Management Practices encompass a wide range of man-made structures, such as stormwater management facilities, or simple everyday preventative house-keeping measures, such as picking up after pets and not littering.
Stormwater management facilities
are developed to reduce the speed of stormwater runoff and provide time
for most pollutants to settle in a holding area where they will not be
transported to streams. Typical stormwater management facilities used in
residential and commercial areas include: dry and wet ponds, rain
gardens, trenches, pervious pavement, wetlands and manufactured
facilities (which are usually underground baffling systems designed to
filter out certain pollutants).
For additional information, or to request this information in an alternate format, please contact the Maintenance and Stormwater Management Division at 703-877-2800, TTY 711, or by e-mail.
Contact Information
Stormwater
maintenance and inspection:
Maintenance and Stormwater Management Division
703-877-2800, TTY 711
E-mail
Stormwater/watershed planning and project implementation:
Stormwater Planning Division
703-324-5500, TTY 711
E-mail
New facilities under construction:
Environmental & Facilities Inspection Division
703-324-1950, TTY 711
E-mail
Additional assistance with private stormwater issues:
Northern Virginia Soil & Water Conservation
District
703-324-1460, TTY 711
E-mail