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Water for Our Future
IISG-98-11 Defining
Water Quality
L. E. Dorworth, Department of
Biological Sciences, Purdue University Calumet, Hammond, Indiana
The term water quality
has different meanings for many people. In essence, water quality is a
measure of the ability of water to support life. Water is used for both
domestic and industrial supplies and is an attraction for recreation and
tourism.
What lowers water
quality?
Unlike a river which
may cleanse itself of pollution, a lake or reservoir traps and recycles
nutrients, silt, toxins and organic matter. Both point and non-point
source pollution contribute to the lowering of water quality in a lake
or reservoir. Runoff, which occurs with rainfall, is a non-point
source of pollution. This runoff carries grease and oil from streets and
also carries fertilizers and insecticides used to treat lawns, gardens
and potted plants. Chemical runoff is mainly attributable to
agricultural activities. Increasing loads of silt and organic matter
also lower water quality. Point source pollution includes flow from
wastewater treatment plants, pulp and paper mills, and food processing
industries. Water pollution generally leads to eutrophication or an
increase in the fertility and productivity of an ecosystem due to an
increased rate of nutrient input. Eutrophication of a body of water is
not beneficial to organisms inhabiting it or to humans.
What are the
symptoms?
Following is a list of
symptoms that would be visible in a body of water that was affected
adversely by human activity.
- Algal blooms which
include surface scums. Hydrilla (Hydrilla verticullata) and
milfoil (Myriophyllum spicatum) tend to be the dominant individuals.
- Lowered
transparency of the water column.
- Water taste and
odor problems
- Tainted fish flesh
- Impaired potable
water supplies
- Dissolved oxygen
depletion
- Fish kills
- Development or
invasion of exotic or nuisance animal populations such as the zebra
mussel (Dreissena polymorpha)
All of the above symptoms are observable problems with a body of water
and are usually a result of eutrophication. It should be emphasized that
eutrophication is a natural process and that some pollution such as
excess nutrients will accelerate the process but other types of
pollution (e.g. pesticides, exotics) may affect the lakes in a negative
way, independent of the eutrophication process. Eutrophication is
directly associated with impaired drinking water supplies.
What indicates a
problem with drinking water?
The water from faucets
may have a disagreeable taste, odor, or color. The treated water prior
to it corning from your faucet may have had high concentrations of
organic molecules. All of these are additives and may lead to human
illness.
If
water quality decreases, what are the costs?
- Economic losses in
the form of decreased property values
- Increased costs for
treating the raw drinking water supplies
- Illness i.e. human
gastrointestinal disorders
- Depressed
recreational/tourism activities
- Money now
prioritized for management and restoration
- A need to build new
reservoirs
- Reduced quality of
aquatic biological resources
What can be done to alleviate the problem?In 1972, the federal Clean
Water Act (CWA) was signed into law. This is an Act whereby a
cooperative effort is put forth by both federal and state agencies to
manage and restore the aquatic ecosystems of the nation's publicly
owned freshwater lakes and reservoirs.
What steps can be taken to improve water quality?
(A) Sewage Systems
The economics of societies throughout the world depend on surface
water for irrigation, industry, potable water supplies and
recreation. The demand for clean, fresh surface water is increasing
whereas the quality is decreasing. One cause of degradation is
stormwater runoff which everyone should consider a concern. This
concern requires examining sewage system control mechanisms that are
in place for communities. As communities grow, sewage systems that
were adequate a few years ago may no longer be able to handle
population growth.
(B) Land management practices
Land management practices also provide
a mechanism for abating eutrophication. Soil erosion should decline
to almost ceasing if vegetation is planted, for example trees and
grass. A forested area between an area used for agriculture and a
stream collects sediments as they move through the area. In essence,
the trees or a buffer strip act as filtering systems whereby
nutrients may be transformed to another form or taken up by the
plants on land. The buffer strip also provides a visual screen along
roadways and reduces noise levels. No tillage or low tillage and
integrated pest management incorporated into agricultural activities
can also reduce soil erosion and pesticide runoff.
(C) Wetlands
Conservation and Construction Another feature of the
landscape that should be considered are the benefits and use of or
the recreation of wetlands. Loss of a wetlands contributes to a
reduction in waterfowl numbers. However, the economic impact of
wetlands loss is felt by property owners who may experience flooding
problems as well as problems with their water supplies. Wetlands aid
in flood control by acting as a sponge and absorbing the excess water
during a heavy rainfall and releasing the extra precipitation slowly
downstream. By absorbingthe excess water, wetlands increases the availability of water during
a dry season. Wetlands are also useful for soil erosion control since
they are often located between bodies of water and high ground. The
plants found in wetlands also bind soil to their roots. Wetlands are
important for filtering the runoff by processing the nutrients,
suspended materials and other pollutants. Finally, wetlands, besides
being a valuable tools for improving the overall water quality, are
also important for recreational opportunities, forestry practices,
hunting, fishing and boating.
Water Quality Issues and Concerns is an ongoing series addressing
relevant water quality issues. For water quality information, contact
Leslie Dorworth, Sea Grant aquatic ecology specialist, at 219
989-2726; dorworth@calumet.purdue.edu
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