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Water Quality
• What is water quality?
• It is the physical, chemical and
biological characteristics of a body
of water.
Water Quality
• Who determines if the water quality for
a body of water is “good” or “bad”?
• Two entities:
– the state you live in
– the EPA.
Water Quality
• In Texas, the governing agency over water
quality is called the Texas Commission on
Environmental Quality (TCEQ). Since there
are two governing agencies over water
quality, the one with the stricter regulations
is the one that is used to compare water
results to determine if water quality is
acceptable or not.
Water Quality
• To determine the water quality of surface water,
there are five main categories that a regulating
agency (TCEQ) will look at:
– Metals
– Organics
– Bacteria
– Dissolved Oxygen
– Dissolved solids
Metals
• Metals like chromium, iron, copper and
mercury pose a threat to drinking water
supplies and human health. They will also
contaminate the fish that live in the water.
Most metal contamination comes from
industrial chemicals and mining.
Organics
Benzene
• Organic pollutants threaten human health
because they are toxic and carcinogenic,
meaning they cause cancer. Some examples
of organic pollutants are benzene, dioxins
and PCB’s. Most organic pollutants come
from pesticides, the oil and gas industry and
industrial chemicals.
Bacteria
• Harmful bacteria like E. coli and
Enterococci pose a health risk to
humans who come in to contact with
the water. Bacteria pollutants come
from untreated sewage, livestock waste
and other sources of waste from warmblooded animals.
Dissolved
Oxygen
• Dissolved oxygen in a body of water is a quick
way to determine the health of the aquatic
system. Any water system that has a dissolved
oxygen concentration less than 5mg/L is put
under stress. A low dissolved oxygen
concentration is usually an indicator of too many
nutrients being introduced into the water.
(Eutrophication)
Eutrophication
• The next step would be to check
ammonia, nitrate and phosphate
concentrations, which come from
commercial fertilizers and municipal
waste.
Dissolved
Solids
• High levels of dissolved solids such as
chloride and sulfate cause water to be
unusable or too costly to treat for drinking
water purposes. Dissolved solids will also
affect the quality of the habitat for aquatic
life. Dissolved solids come from all types of
human activities along with some natural
sources.
NPDES
• What keeps big industries from dumping
their waste into the water supply?
The EPA. The specific branch of the EPA
that is in charge of this is called the NPDES
(National Pollutant Discharge Elimination
System).
• Every business that has the potential to discharge
pollutants into the water supply is required to
obtain an NPDES permit. This permit lists the
potential compounds that the business might
discharge and sets up a schedule to determine
when their wastewater needs to be tested to make
sure they are not contaminating the water supply.
• Who regulates the agricultural industry?
• NO ONE!!
• Direct quotes from EPA:
• “A strong agricultural industry is essential to the Nation's
economic stability, the viability of many rural communities, and
the sustainability of a healthful and high quality food supply for
the American public.”
• “For most agricultural producers, a variety of voluntary
programs provide the technical and financial assistance to help
producers meet technical standards and remain economically
viable.”
• What does this mean to the environment?
Eutrophication
• One example is the 7000 square mile “dead zone”
in the Gulf of Mexico.