Frequently Asked Questions
- Where does stormwater go?
- Why has stormwater runoff become such
- How can I reduce runoff?
- What is an impervious surface?
- How can I landscape my yard in ways
to reduce runoff and protect the environment?
- What are some simple changes I can
make to protect our waters?
1. Where does stormwater
Stormwater flows directly into our rivers, lakes, streams
and the ocean or into a stormwater system through a
Storm drains are frequently located in parking lots
and along the curbs of roadways. The grate that prevents
larger objects from flowing into the storm sewer system
is called a catch basin. Once below ground, the stormwater
flows through pipes, which lead to an outfall where
the stormwater usually enters a stream, river or lake.
In some areas, the outfall may lead to a stormwater
management basin. These basins control the flow and
improve the quality of stormwater, depending on how
they are designed. They can also recharge groundwater
In some urban areas of the state, the stormwater and
sanitary sewer systems may be combined. Here both stormwater
and sewage from households and businesses travel together
in the same pipes and are treated at sewage treatment
plants except during heavy rains. During these occasions,
both the stormwater and untreated sewage exceed the
capacity of the treatment plant, and this overflow is
directed into local waterways.
2. Why has
stormwater runoff become such a problem?
Urbanization and increasing commercial and residential
development have a great impact on local water resources.
More impervious surfaces (roads, rooftops, parking lots
and other hard surfaces that do not allow stormwater
to soak into the ground) increase the rate of stormwater
runoff. This means a greater volume of water carrying
pollution into surface waters and less water soaking
into the ground. These contaminants include litter;
cigarette butts and other debris from sidewalks; motor
oil poured into storm sewers; settled air pollutants;
pet wastes; yard wastes; and pesticides and fertilizers
from lawn care. Less water soaking into the ground also
lowers ground water levels, which can dry up streams
and hurt stream ecosystems, and can reduce the supply
of well water.
Stormwater also erodes stream banks. This in turn degrades
habitat for plant and animal life that depend on clear
water. Sediment in water clogs the gills of fish and
blocks light needed for subsurface plants. The sediment
can also fill in stream channels, lakes and reservoirs,
covering the bottom and negatively affecting flow, plants
and aquatic life.
3. How can I reduce
There are inexpensive ways to control excess runoff
created by patios, driveways, sidewalks and roofs. Whatever
the soil drainage condition in your neighborhood, landscaping
and careful grading of your property's surface area
can be used to control runoff, reduce its speed and
increase the time over which it is released. For example,
land immediately adjacent to your house needs to have
a downhill slope so that water does not seep through
the foundation. Once the water has been carried 10 feet
from the house, the surface should be graded so that
runoff is released gradually.
Surface runoff can be decreased and ground water infiltration
increased by following these suggestions:
- Install gravel trenches along driveways or patios
to collect stormwater and filter it into the soil.
- Plant sod on bare patches in your lawn as soon as
possible to avoid erosion.
- Grade all areas away from your house at a gentle
- Use a grass swale, which is a man-made depression,
to move water from one area to another.
- Plant shrubs and trees to promote infiltration (see
chapter on lawn and garden care).
- If you are building a new home or in a position
to consider regrading your property, you may want
to create a basin, which will hold all runoff and
allow it to infiltrate the soil over a longer period
of time. This should be done only where drainage is
good. Alternatively, you may be able to create a gently
rolling surface or a system of berms, or mounds, and
swales to slow run-off. Berms and swales are slight
elevations and depressions in the surface that provide
channels along which water will flow. If you have
a wet area, you may be able to move the basin to a
less used area of the yard – around shrubs or
trees, for example – by installing a swale to
carry the water across the yard. Be advised that most
activities performed in regulated wetlands require
a permit. Contact DEP Land Use Regulation for information
at (609) 292-0060. Plant trees and shrubs that thrive
in wet soils in the new wet area.
4. What is an impervious
One method of reducing stormwater runoff is to minimize
the amount of impervious surfaces such as concrete sidewalks
and asphalt driveways. Impervious surfaces do not allow
runoff to seep into the ground. Use pervious surfaces
instead. A paving surface that allows water to soak
in may seem impossible, but there are many materials
that provide the durability of concrete while allowing
rainwater to filter down into the ground. If you are
planning a new patio, walkway or driveway, there are
several attractive alternatives to concrete. Some examples
of these needs are:
- Wood or recycled material decks, usually installed
for their functional good looks, can serve as a form
of porous pavement. Redwood, cedar and treated pine
are as durable as most nonporous surfaces such as
asphalt or concrete. Decking allows rainwater to soak
into the ground beneath it, and the space between
the planks provides ample room for precipitation to
drain directly onto the soil surface. As long as minimal
air space is maintained between the soil surface and
the decking, wood rot can be minimized.
- If you are installing a new patio or rebuilding
a crumbling sidewalk, you do not need to use the typical
slab concrete. Using bricks, interlocking pavers or
flat stones (flagstone, bluestone or granite), you
can construct an attractive, durable walkway. If placed
on well-drained soil or on a sand or gravel bed, these
modular pavers allow rainwater infiltration. Avoid
using chemicals to control weeds growing in the joints
between the pavers; Corsican mint or moss can crowd
out weeds and add beauty to the paved area.
- Pre-cast concrete lattice pavers also rest on a
bed of sand and gravel and allow rain to soak slowly
into the ground.
- Dutch drains, which are containers of gravel with
holes used to infiltrate water from rooftops directly
into the ground, carry water from rain spouts into
the soil, where it gradually filters into the ground.
These types of materials can be used wherever natural
soil drainage is good and there are no problems with
either bedrock near the surface or seasonal high water
Significant strides have also been made in the last
few decades in developing porous asphalt pavement. This
material is similar to conventional asphalt in durability,
but it contains a much smaller percentage of very fine
particles. As a result, the asphalt allows water to
soak through into the soil below.
5. How can I landscape
my yard in ways to reduce runoff and protect the environment?
Planting trees is one way to protect land and local
streams from the damage caused by excessive runoff and
erosion. Trees have long been appreciated for their
beauty, but their help in minimizing erosion is not
as well known. Landscaping by planting shrubs, trees
and ground covers has definite environmental benefits
and enhances the appearance and value of property. Realtors
suggest that mature trees increase the value of homes
as well as the speed of sale.
Plants and trees can create outdoor rooms where you
and your family can work and play. Well-planned landscaping
can reduce heating and cooling costs for your house
by as much as 30 percent. New shrubs and trees may attract
birds and wildlife. Trees, shrubs and ground cover also
require less maintenance than grass. Because trees and
shrubs require less fertilizer and fewer herbicides
than grass, the chances of polluting streams is minimized.
Another possibility is landscaping for wildlife. By
selecting appropriate plants, landscaping can both reduce
water pollution and serve wildlife. Four basic elements
are needed for wildlife: food, water, shelter and space.
Food can be supplied through vegetation that provides
seeds, nuts or berries. Water, if not available nearby
as a stream or lake, can be provided as a small pool
or pond. Vegetation, a pond or even a brush pile can
serve as shelter, providing protection from predators
and the weather. Space needs vary among wildlife but
include enough room to reproduce, find food and carry
on the different stages of their life cycle. The specifics
depend on whether you are trying to attract a variety
of wildlife or a certain species, such as butterflies
or hummingbirds. For more information, contact DEP Division
of Fish, Game and Wildlife, CN 400, Trenton, NJ 08625-0400.
An environmentally sensitive landscape reduces the
erosive force of rainwater runoff and increases the
value of your home. By planting trees, shrubs and ground
cover, you encourage excess rainwater to filter slowly
into the soil instead of flowing directly into storm
drains or nearby streams. Choosing trees and plants
that are appropriate for your soil and growing conditions
will ensure that you will have a beautiful yard.
For more information on landscaping, see
the chapter on Lawn and Garden Care.
6. What are some simple
changes I can make to protect our waters?
By following these few simple guidelines, you can make
your home more attractive and help prevent erosion:
- Never dump motor oil, grass trimmings, leaves,
animal waste or other pollutants into the roadway
or stormwater catch basins.
- Landscape your yard to minimize rainwater runoff.
- Divert rain from paved surfaces onto grass to permit
- Preserve the established trees in your neighborhood,
which help minimize the damage caused by surface runoff.
- Choose the appropriate plants, shrubs and trees
for the soil in your yard; do not select plants that
need lots of watering, which increases surface runoff.
- Consult your local nursery or your county’s
Rutgers Cooperative Research and Extension office
for advice on which plants, shrubs and trees will
grow well in your yard.