What is nonpoint source
Nonpoint source pollution
(NPS) is sometimes called polluted runoff. It may be hard to recognize
and is often hard to control. It is pollution or runoff that comes
from diffuse sources, rather than from a point source
like the end of a discharge pipe.
Nonpoint source pollution
runs off the land and can affect lakes rivers, wetlands, groundwater,
and drinking water supplies. Sediment and nutrients are the most commonly
recognized nonpoint pollutants, but toxic contaminants (heavy metals
and man-made chemicals such as pesticides and solvents), airborne
inputs, and pathogens (disease-causing organisms) from human or animal
waste are also NPS pollutants.
Where does nonpoint
source pollution come from?
include urban and agricultural runoff, mining, silviculture (forestry),
wastewater treatment, construction and transportation, and recreational
activities. NPS from urban and residential areas includes nutrients
and pesticides from lawn and garden care, automotive fluids, salt
and sand, pet waste, hazardous household waste, and airborne emissions
from cars and industry. Agricultural sources include fertilizer and
pesticides from crop production, manure management, sediment, and
drainage. Human activities that disturb the land, such as mining,
clearcutting, road building, or construction can greatly increase
the nonpoint pollutant load. Inadequate wastewater treatment (municipal
or on-site) can contribute nutrients, pathogens, and toxic chemicals
to surface or groundwater. Many everyday activities have the potential
to produce nonpoint source pollution.
How can nonpoint source
pollution be controlled?
Reducing the effects
of nonpoint source pollution requires reducing the amount of polluted
runoff and improving the quality of water that runs off the land.
Nonpoint source pollution can be managed most effectively at the source,
by implementing Best Management Practices (BMPs) to eliminate or minimize
polluted runoff. Alternatively, NPS can be managed through controls
built into the path of runoff, such as sedimentation ponds or wetland
detention systems that slow, settle, or filter the runoff.
The most expensive
way to manage the effects of NPS is to clean up after the fact. The
expense of cleaning up is not only financial, it also
takes time and has ecological consequences. Using alum or other treatments
to seal lake bottoms and trap excessive nutrients, dredging ponds
or ditches to remove sediment, or intensively treating water to make
it safe to drink are examples of how systems are treated to cope with
the impacts from nonpoint source pollution.
What can I do to reduce
nonpoint source pollution?
You can do many things
on your property to reduce the amount of nonpoint pollution that reaches
your lake or river. You can minimize erosion and sedimentation by
keeping bare soil covered, mulching gardens, establishing or maintaining
a buffer of native vegetation between your lawn and the lake or river,
and maintaining healthy, dense turf. A dense turf lawn can be effective
in reducing runoff, but will probably need fertilizer. Have a soil
test BEFORE applying fertilizer, choose zero-phosphorus fertilizer,
especially in shoreland areas, and apply carefully to prevent excess
fertilizer from reaching the water. Maintain your lawn with proper
mowing, sprinkling and aeration to increase infiltration and reduce
runoff. Reduce the amount of impervious area on your property and
divert downspouts from your roof into a rain garden or seepage pit
to slow runoff. Eliminate bare, compacted paths by substituting a
boardwalk, gravel or mulch, or steps down to the waters edge.
Encourage or restore
the native vegetation along your shoreline to further slow runoff
and filter nutrients that might otherwise reach your lake or stream.
The benefits of a shoreline buffer strip also include improving habitat,
increasing privacy, enhancing aesthetics, and deterring nuisance geese.
Who can I contact if
I have questions or a problem related to nonpoint source pollution?
Check your local telephone
listing, the Who to Contact
section of the Minnesota Shoreland Management Resource Guide Web site,
or the Web sites listed below for:
What are some additional
resources related to agriculture near water?
- Protecting Water
Quality in Urban Areas. 2000. Minnesota Pollution Control Agency
- Protecting Minnesotas
Waters... The Land-use Connection. 1986. Minnesota Pollution Control
- A Watershed Approach
to Urban Runoff. A Handbook for Decision Makers. 1996. Terrene
- Municipal Nonpoint
Source Pollution Guidebook.1994. New York Sea Grant Extension