Effects of Stormwater Runoff
is essential for life and it is our most precious resource.
Both point and non-point sources contribute to the increase
of water pollution and at least 50% of water pollution is
generated from point and non-point sources.
In order to understand the importance
of Stormwater Runoff and the importance of why it needs to
be managed let us begin by reviewing some of the basic facts.
Point Source Pollution
Point source pollution is typically
generated from pollutants entering a stream or lake or from
one specific source. Point sources of pollution may include:
- Discharge pipe from a municipal or industrial wastewater
- Overflows and bypasses from sewerage systems
- Chemical spills from oil and gas operations
- Animal confines and feeding operations
- Un-permitted and illegal discharges into storm sewer
Non-source point pollution comes
from a variety of diffuse sources. When rainfall comes into
contact with parking lots, roadway, agricultural areas, lawns,
etc. it picks up and carries pollutants, depositing them into
streams, lakes and rivers. Non-point sources may include:
- Excessive application of
fertilizer, herbicides, and insecticides
- Construction site sediment
- Erosion of stream banks
- Animal waste
- Oil and grease
- Chemicals poured into storm drains
- Toxic or hazardous substances
stored outside and exposed to rain
Approximately 70% of the earth is
covered with water, but only about 1% is available for human
use. Water is continuously moving. It is heated by the sun,
its vapor is carried by the wind, and it condenses into clouds
and falls to the ground as rain, snow or other forms of precipitation.
When it returns to the ground much
of the water travels as runoff into the oceans, rivers, lakes
and streams or evaporates back into the atmosphere. A quantity
of the water percolates into the soil forming groundwater
and some of the water is intercepted by plant life where it
transpires into the atmosphere.
The impacts of urbanization and
stormwater runoff begins as rain and picks up pollutants from
land surfaces as it makes its way to nearby streams and lakes.
As it comes in contact with streets, parking lots and lawns,
etc., it picks up trash debris and other pollutants. Runoff
also collects sediments from construction sites, leaking fluids
from vehicles and disease-causing bacteria from leaking septic
systems or pet waste. These are just a few examples of pollutants
generated in urban areas. The character of stormwater runoff
changes as land is urbanized or developed for residential,
commercial, industrial or other uses. Paved surfaces result
in more runoff entering streams at a faster rate. This causes
stream erosion and the destruction of aquatic life and its
To learn more about stormwater runoff
and how you can reduce pollutants, visit the U.S.
Environmental Protection Agency website.