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Water Qualty
Lakes, streams, rivers, wetlands--our nation's
waters are a national treasure. Clean water supports an '
incredible diversity of plant and animal life, and it is a
source of drinking water and food that sustains human life.
It is a valuable resource that is used for many other
activities, such as boating and swimming. It is also used by
industry and for agricultural purposes. For these, and
many more reasons, the U. S. Environmental Protection
Agency (EPA), states*, and Indian tribes*, carry out
programs to protect the quality of the nation's waters.
Water Quality Standards
Water quality standards are the foundation of
.the nation's ;surfae~e water qualify protection prpgfSni'T
States set water quality standards for all surface waters
within their boundaries. Water quality standards form
; %;legal:basis foj-cpnfrojs on thsjimourit of poilutSitsJ
entering these waters from sources such as industrial""
facilities, wastewater treatment plants, and storm
sewers. They are also the technical basis for reducing
runoff from rural and urban areas. Water quality
standards comprise three components, each of which
are specific to a defined body of water:
B The Use (such as swimming and boating)
designated for the water body
H Water quality criteria, or limits on chemical
concentrations that may be present in the wa
body
H Antidegradation Policy to protect existing w;
quality
This brochure focuses on the second
component: water quality criteria.
Water Quality Criteria
Many types of microscopic plants and anima
such as plankton, water beetles, and insects that live ir
or on the water, serve as food for small fish. Small fis
are eaten by larger fish which, in turn, are consumed b
even larger fish. These large fish may ultimately be
consumed by humans. All life along this food chain is
dependent on the water environment and it is for this
reason that the quality of the nation's surface waters
must be protected.
The Clean Water Act directs EPA to develop
criteria for water quality that accurately reflect the late:
. scientific knowledge about the effects of pollutants on
aquatic life and human health. In developing these
criteria, EPA examines the effects of specific pollutant;
. .on plankton, fish, shellfish, wildlife, plant life,
,,fesjheticj,_and,rec|eationin any body of water,. This
includes specific information on the concentration and *
dispersal of pollutants through biological, physical, and
-.chemical processes as well as the effects of pollutants p
Biological communities as a wholes1"'•-'-"'•—~-~--i-^x'^-=-^&
'The terms state and Indian tribe, as used in this brochure,
refer to the 50 states, U. S. Territories, the District of '' '
Columbia and Indian tribes that are authorized to administer
the water quality standards program.
Biological
Criteria f"°
~LT~
Aquatic f^->
Life V — -
Criteria _|
'Human
Health
Criteria
L_TL_
Sediment
Quality
Criteria
Guidance
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States may use the criteria that are developed
by EPA to help'-set water quality standards that protect
the uses of their waters or they may develop their own
water quality criteria. EPA publishes human health and
aquatic life criteria and is currently developing sediment
1 and biological criteria. These criteria are complemen-
tary: each is designed to protect specific types of living
organisms or ecological systems from the adverse
effects of pollution.
Human Health Criteria
People can potentially be exposed to water
pollutants when they drink untreated surface water or
eat fish, shellfish, or wildlif e that have been ™
_. Contaminated by pollutants in surface .waters,, To reduce-
7 'the risk to humans from these sources,""EPA; scientists "
research information to determine the levels at which
-. ^^jfitphsmicals are not likely to adversely affect
• human3fejrth. EPA publishes thesele%^fisrhilmair ""'
health criteria that the states use, along with other
information, to set allowable concentrations of
pollutants in their water quality standards. In this way,
EPA and the states work together to protect people from
exposure to harmful pollutants in surface waters.
Aquatic Life Criteria
Aquatic life criteria provide protection for
plants and animals that are found in surface waters.
EPA develops these criteria as numeric limits on the
amounts of chemicals that can be present in river, lake,
or stream water without harm to aquatic life. Aquatic '
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life criteria are designed to provide protection for both
freshwater and saltwater aquatic organisms from the
effects of acute (short term) and chronic (long term)
exposure to potentially harmful chemicals. Aquatic life
criteria are based on toxicity information and are
developed to protect aquatic organisms from death,
slower growth, reduced reproduction, and the
accumulation of harmful levels of toxic chemicals in
their tissues that may adversely affect consumers of
such organisms.
Sediment Quality Criteria Guidance
In a healthy aquatic community, sediments
provide a habitat for many living organisms. Worms,
plants, and tiny micro-organisms living in or on the '
: sediment sustain the fish;and shellfish that, in turn, "
nourish larger fish, wildlife, and man.
.^Gontrolling fee concentration of pollutants in
the sediment helps'to pfotecFbottom dwelling species
and prevents harmful toxins from moving up the food
chain and accumulating in the tissue of animals at
progressively higher levels. This is particularly
important at the lower levels of the food chain because
the concentration of many pollutants may increase at
each link in the food chain. A pollutant level in the
sediment that does not harm snails or small fish may
bioaccumulate in the food chain and become very
harmful to larger fish, birds, mammals, wildlife, and
people.
EPA develops sediment quality criteria
guidance on the concentrations or amounts of indrvidual
chemicals that can be present in river, lake, or stream
sediments and still protect sediment-dwelling organisms
-and ultimately animals higher in the food chain-from
the harmful effects of toxic pollutants.
Biological Criteria
The water body depicted inside this brochure is
shown in its natural condition. It is free from the
harmful effects of pollution, habitat loss, and other
negative stressors. It is characterized by a particular
, biological diversity and abundance of organisms. This
biological integrity-or natural structure and function of
aquatic life-can be dramatically different in various
types of jwater bodies in different parts of the country.
Because of this, EPA is developing methodologies that
Jtetest&ri use to as|e?s'the biological3ntegrity of their"""
waters and, in so doing, set protective water quality
standards. These methodologies will describe scientific
methodsJpr determining spartidxilafaquatic ,. ":l~;f'.'
community's health and for maintaining optimal
conditions in various bodies of water.
For More Information
For information about your state's water quality
standards contact the state or Indian tribal agency
responsible for water quality. You may also contact the
U. S. Environmental Protection Agency, Office of Water,
Office of Science, and Technology, (Mail Code 4301),
Washington, D. C. 20460. Information related to water
quality standards and criteria may also be obtained by
visiting the Office of Water, Office of Science and
Technology's Home Page at: http://www.epa.gov/OST.
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