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Public Works Department
Storm Sewers:
PROTECTING WATER QUALITY FROM URBAN RUNOFF. CLEAN WATER IS EVERYBODY’S
BUSINESS.
In urban and suburban areas, much of the land surface is covered by
buildings and pavement, which do not allow rain and snowmelt to soak into
the ground. Instead, most developed areas rely on storm drains to carry
large amounts of runoff from roofs and paved areas to nearby waterways. The
storm water runoff carries pollutants such as oil, dirt, and lawn
fertilizers directly to streams and rivers, where they seriously harm water
quality. To protect surface water quality and groundwater resources,
development should be designed and built to minimize increases in runoff.
EPA
United States
Environmental Protection Agency
EPA 841-F-03-003
The most recent National – Water Quality Inventory reports that runoff from
urbanized areas is the leading source of water quality impairments to
surveyed estuaries and the third-largest source of impairments to surveyed
lakes.
Did you know that because of impervious surfaces like pavement and rooftops,
a typical city block generates more than 5 times more runoff than a woodland
area of the same size?
HOW URBANIZED AREAS AFFECT WATER QUALITY
Increased Runoff
The porous and varied terrain of natural landscapes like forests, wetlands,
and grasslands traps rainwater and snowmelt and allows them to filter slowly
into the ground. In contrast, impervious (nonporous) surfaces like roads,
parking lots, and rooftops prevent snowmelt from infiltrating, or soaking,
into the ground. Most of the rainfall and snowmelt remains above the
surface, where it runs off rapidly in unnaturally large amounts.
Storm sewer systems concentrate runoff into smooth, straight conduits. This
runoff gathers speed and erosion power as it travels underground. When this
runoff leaves the storm drains and empties into a stream, its excessive
volume and power blast out stream banks, damaging streamside vegetation and
wiping out aquatic habitat. These increased storm flows carry sediment loads
from construction sites and other denuded surfaces and eroded stream banks.
They often carry higher water temperatures from streets, rooftops, and
parking lots, which are harmful to the health and reproduction of aquatic
life.
The loss of infiltration from urbanization may also cause profound
groundwater changes. Although urbanization leads to great increases in
flooding during and immediately after wet weather, in many instances it
results in lower stream flows during dry weather. Many native fish and other
aquatic life cannot survive when these conditions prevail.
Increased Pollutant Loads
Urbanization increases the variety and amount of pollutants carried into
streams, rivers, and lakes. The pollutants include:
Sediment
Oil, grease, and toxic chemicals from motor vehicles
Pesticides and nutrients from lawns and gardens
Viruses, bacteria, and nutrients from pet waste and failing septic systems
Road salts
Heavy metals from roof shingles, motor vehicles, and other sources
Thermal pollution from dark impervious surfaces such as streets and rooftops
These pollutants can harm fish and wildlife populations, kill native
vegetation, foul drinking water supplies, and make recreational area unsafe
and unpleasant.
Relationships between impervious cover and surface runoff: Impervious cover
in a watershed results in increased surface runoff. As little as 10 percent
impervious cover in a watershed can result in stream degradation.
Managing Urban Runoff
What Homeowners Can Do:
To decrease polluted runoff from paved surfaces, households can develop
alternatives to areas traditionally covered by impervious surfaces. Porous
pavement materials are available for driveways and sidewalks, and native
vegetation and mulch can replace high maintenance grass lawns. Homeowners
can use fertilizers sparingly and sweep driveways, sidewalks, and roads
instead of using a hose. Instead of disposing of yard waste, they can use
materials to start a compost pile. Homeowners can learn to use integrated
Pest Management. (IMP) to reduce dependence on harmful pesticides
In addition, households can prevent polluted runoff by picking up after pets
and using, storing, and disposing of chemicals properly. Drivers should
check their cars for leaks and recycle their motor oil and antifreeze when
these fluids are changed. Drivers can also avoid impacts from car wash
runoff (e.g. detergents, grime, etc.) by using car wash facilities that that
do not generate runoff. Households served by septic systems should have them
professionally inspected and pumped every 3 to 5 years. They should also
practice water conservation measures to extend the life of their septic
systems.
Controlling Impacts from New Development
Developers and city planners should attempt to control the volume of runoff
from new development by using low impact development, structural controls,
and pollution prevention strategies. Low impact development includes
measures that conserve natural areas (particularly sensitive hydrologic
areas like riparian buffers and infiltrate soils); reduce development
impacts; and reduce site runoff rates by maximizing surface roughness,
infiltration opportunities, and flow paths.
Controlling Impacts from Existing Development
Controlling runoff from existing urban areas is often more costly than
controlling runoff from new developments. Economic efficiencies are often
realized through approaches that target “hot spots” of runoff pollution or
have multiple benefits, such as high-efficiency street sweeping (which
addresses aesthetics, road safety, and water quality). Urban planners and
others responsible for managing urban and suburban areas can first identify
and implement pollution prevention strategies and examine source control
opportunities. They should seek out priority pollutant opportunities,
protect natural areas that help control runoff, and finally begin ecological
restoration and retrofit activities to clean up degraded water bodies. Local
governments are encouraged to take lead roles in public education efforts
through public signage, storm drain marking, pollution prevention outreach
campaigns, and partnerships with citizen groups and businesses. Citizens can
help prioritize the clean-up strategies, volunteer to become involved in
restoration efforts, and mark storm drains with approved “don’t dump”
messages.
Related Publications
Turn Your Home into a Storm water Pollution Solution! www.epa.gov/nps
This website links to an EPA homeowner’s guide to healthy habits for clean
water that provides tips for better vehicle and garage care, lawn and garden
techniques, home improvement, pet care, and more.
National Management Measures to Control Non-point Source Pollution from
Urban Areas www.epa.gov/owow/nps/urbanmm
This technical guidance and reference document is useful to local, state,
and tribal managers in implementing management programs for polluted runoff.
It contains information on the best available, economically achievable means
of reducing pollution of surface waters and groundwater from urban areas.
Onsite Wastewater Treatment System Resources www.epa.gov/owm/onsite
This website contains the latest brochures and other resources from EPA for
managing onsite wastewater treatment systems (OWTS) such as conventional
septic systems and alternative decentralized systems. These resources
provide basic information to help individual homeowners, as well as
detailed, up-to-date technical guidance of interest to local and state
health departments.
Low Impact Development Center www.lowimpactdevelopment.org
This center provides information on protecting the environment and water
resources through integrated site design techniques that are intended to
replicate preexisting hydrologic site conditions.
Storm water Manager’s Resource Center (SMRC) www.stormwatercenter.net
Created and maintained by the Center for Watershed Protection, this resource
center is designed specifically for storm water practitioners, local
government officials, and others that need technical assistance on storm
water management issues.
Strategies: Community Responses to Runoff Pollution www.nrdc.org/water/pollution/storm/stoinx.asp
The Natural Resources Defense Council developed this interactive web
document to explore some of the most effective strategies that communities
are using around the nation to control urban runoff pollution. The document
is also available in print form and as an interactive CD-ROM.
For More Information
U.S. Environmental Protection Agency
Non-point Source Control Branch (4503T)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
www.epa.gov/nps
At this time we would like to inform our residents not to dump anything into
our sewers, as this goes directly into the river and will become drinking
water for someone else downstate. It is a violation of Article XVII
sec.7-618 and can carry a fine of $500.00 for each offense. If you have any
hazardous waste, IEPA has scheduled pick-ups. For information, call
1-847-294-4000 or check out their web site for dates and locations at
www.epa.stateil.us (hazardous waste). If you see anyone dumping into the
sewer you can call 1-800-332-DUMP or 708-924-7390.
IN THE WORKS |
SEASONAL |
STORM SEWERS |
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