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These definitions of water-related terms might help you understand
our site better. It is compiled from a number of sources and should
not be considered an "official" U.S. Geological Survey
water glossary. A detailed water glossary is kept by
the
Water Quality Association, and
an extremely detailed water dictionary is offered by
the
Nevada Division of Water Planning).
A | B | C |
D | E | F |
G | H |
M | N | O |
P | R |
S | T | W
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A
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acid--a substance that has a pH of less than 7, which
is neutral. Specifically, an acid has more free hydrogen ions (H+)
than hydroxyl ions (OH-).
alkaline--sometimes water or soils contain an amount of alkali (strongly basic)
substances sufficient to raise the pH value above 7.0 and be harmful to the growth of crops.
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B
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bacteriophages--a virus that only infects only bacterial cells.
base flow--streamflow coming from ground-water seepage into a stream.
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C
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clostridium perfringens--an anaerobic, spore-forming, rod-shaped
bacteria. It is consistently found in high concentrations human and
animal feces as well as sewage. Clostridium perfringens must be
analyzed under anaerobic conditions by highly trained technicians. It
is useful as a water-quality indicator because it forms spores that
are more resistant to disinfection and environmental stresses than
other indicator bacteria. This makes it indicative of remote,
intermittent, and possibly point-source pollution and may be used as a
surrogate for stress-resistant organisms.
coliphage--a virus that only infects E. coli and
other forms of coli bacteria.
combined sewer overflow--a discharge of untreated
sewage and stormwater to a stream when the capacity of a combined
storm/sanitary sewer system is exceeded by storm runoff.
cubic feet per second (cfs)--a rate of the flow, in streams and rivers, for
example. It is equal to
a volume of water one foot high and one foot wide flowing a distance of one foot in one second.
One "cfs" is equal to 7.48 gallons of water flowing each second. As an example, if your car's
gas tank is 2 feet by 1 foot by 1 foot (2 cubic feet), then gas flowing at a rate of 1 cubic foot/second would
fill the tank in two seconds.
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D
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diel sampling--sampling which encompasses both a day
and night cycle. This type of sampling is designed to assess changes
in water quality that may be related to changes in parameters such as
water temperature, discharge, and sunlight -all of which vary
throughout the day.
discharge--the volume of water that passes a given location
within a given period of time. Usually expressed in cubic feet per second.
drainage basin--land area where precipitation runs off into streams, rivers, lakes,
and reservoirs. It is a land feature that can be identified by tracing a line along the
highest elevations between two areas on a map, often a ridge. Large drainage basins,
like the area that drains into the Mississippi River contain thousands of
smaller drainage basins. Also called a "watershed."
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E
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effluent--outflow from a particular source, such as
a stream that flows from a lake or liquid waste that flows from a
factory or sewage treatment plant.
Enterococci-a subgroup of the more general group of fecal
streptococci bacteria. Enterococci is also a preferred indicator
organism for freshwaters and marine waters used for recreation. It has
been found to be superior to fecal streptococci as a predictor of
swimming-associated gastroenteritis. Numbers of enterococci in fresh
or marine surface waters can be translated to a rate of
swimming-associated gastroenteritis.
Equal-Width Increment method (EWI)--standard field sampling
technique developed to provide a more accurate assessment of water
quality parameters at a fixed site on a river or stream. By dividing
the total width of the stream or river into smaller areas of equal
width and sampling each individually, a more accurate determination of
water quality constituents can be made, especially for those that may
vary spatially across the width of a river or stream.
Escherichia coli (E. coli)--a rod shaped bacteria commonly
found in the gastrointestinal tract and feces of warm blooded
animals. It is a member of the fecal coliform group of bacteria and is
distinguished from them by its inability to break down urease. The addition of
urea substrate confirms that colonies are E. coli. This bacteria is a
preferred indicator for freshwater recreational waters and its
presence provides direct evidence of fecal contamination from warm
blooded animals. Although usually harmless, E. coli can cause
illnesses such as meningitis, septicemia, urinary tract, and
intestinal infections. A recently discovered strain of E. coli
(E. coli 0157:H7) can cause severe disease and may be fatal in small
children and the elderly.
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F
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fecal coliform--are a subgroup group of coliform
bacteria used to establish the first microbial water quality
standards. Its ability to grow at an elevated temperature (44.5 C)
separate it from the total coliforms and make it a more accurate
indicator of fecal contamination by warm-blooded animals.
The presence of fecal coliforms in water
indicates that fecal contamination of the water has occurred and that
consuming or swimming in the water may result in illness.
fecal streptococci--a group of bacteria found in the
gastrointestinal tract of man, domestic animals, and birds. These
bacteria do not reproduce in the environment and survive for
relatively long periods of time. The presence of this group of
bacteria indicates fecal contamination and consuming or swimming in
the water may result in illness.
fixed-interval sampling--a type of sampling design that attempts to
assess trends in water quality at a stationary site over a specified
period of time.
F-specific coliphage--bacteriophages that infect only
male strains of coli bacteria by attaching to the sex cell (F-cells)
of the bacteria. Certain strains of these coliphages may be specific
for human fecal contamination.
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G
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gage height--the height of the water surface above the gage datum (zero point). Gage height is
often used interchangeably with the more general term, stage, although gage height is more appropriate
when used with a gage reading.
gaging station--a site on a stream, lake, reservoir or other body of water where observations and hydrologic
data are obtained. The U.S. Geological Survey measures stream discharge at gaging stations.
giardiasis--a disease that results from an infection by the protozoan parasite Giardia Intestinalis, caused
by drinking water that is either not filtered or not chlorinated. The disorder is more prevalent in children than in
adults and is characterized by abdominal discomfort, nausea, and alternating constipation and diarrhea.
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H
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human enteric virus--a virus that infects the normal
bacterial flora of the human gastrointestinal tract.
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M
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main stem--the principal course of a river or stream.
membrane filter technique--a standard method for the
detection and enumeration of bacteria in the aquatic environment.
This method provides a direct count of bacteria in water based on the
development of colonies on the surface of a membrane filter through
which water from the environment has been passed. After counting, the
number of bacteria in the water can be determined based on the amount
of water passed through the filter and the number of colonies formed.
milligram (mg)--one-thousandth of a gram.
milligrams per liter (mg/l)--a unit of the concentration of a constituent in water or wastewater. It
represents 0.001 gram of a constituent in 1.000 milliliter (mL) of water.
It is approximately equal to one part per million (PPM).
municipal water system--a water system that has at least 15 service
connections or which regularly
serves 25 individuals for 60 days; also called a public supply system
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N
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nephelometric turbidity unit (NTU)--unit of measure for the
turbidity of water. Essentially, a measure of the cloudiness of water as
measured by a nephelometer. Turbidity is based
on the amount of light that is reflected off particles in the water.
nonpoint source--a pollution source that cannot be
defined as originating from discrete points such as pipe discharge.
Areas of fertilizer and pesticide applications, atmospheric
deposition, manure, and natural inputs from plants and trees are types
of nonpoint source pollution.
nonpoint source (NPS) pollution--pollution
discharged over a wide land area, not from one specific
location. These are forms of diffuse pollution caused by sediment,
nutrients, organic and toxic substances originating from land-use
activities, which are carried to lakes and streams by surface
runoff. Nonpoint
source pollution is contamination that occurs when
rainwater, snowmelt, or irrigation washes off plowed fields, city
streets, or suburban backyards. As this runoff moves across the land
surface, it picks up soil particles and pollutants, such as nutrients
and pesticides.
nutrients--element or compound essential for animal and plant growth. Common nutrients include nitrogen, phosphorus, and potassium.
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O
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outfall--the place where a sewer, drain, or stream discharges; the outlet or structure through which
reclaimed water or treated effluent is finally discharged to a receiving water body.
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P
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pathogen--any disease causing agent.
point source--a source at a discrete location such as a discharge pipe, drainage ditch, tunnel, well, concentrated livestock operation, or floating craft.
primary wastewater treatment--the first stage of the wastewater-treatment process
where mechanical methods, such as filters and scrapers, are used to remove pollutants.
Solid material in sewage also settles out in this process.
public supply--water withdrawn by public governments and agencies, such
as a county water department, and by private
companies that is then delivered to users.
Public suppliers provide water for domestic, commercial, thermoelectric power,
industrial, and public water users. Most people's household water is delivered by a public water
supplier. The systems have at least 15 service connections (such as households, businesses, or
schools) or regularly serve at least 25 individuals daily for at least 60 days out of the year.
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R
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runoff--(1) That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled
surface streams, rivers, drains or sewers.
Runoff may be classified according to
speed of appearance after rainfall or melting snow as direct runoff or base runoff, and according to source as
surface runoff, storm interflow, or ground-water runoff. (2) The total discharge described in (1), above, during
a specified period of time. (3) Also defined as the depth to which a drainage area would be covered if all of the
runoff for a given period of time were uniformly distributed over it.
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S
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secondary wastewater treatment--treatment (following
primary wastewater treatment) involving the biological process of
reducing suspended, colloidal, and dissolved organic matter in
effluent from primary treatment systems and which generally removes 80
to 95 percent of the Biochemical Oxygen Demand (BOD) and suspended
matter. Secondary wastewater treatment may be accomplished by
biological or chemical-physical methods. Activated sludge and
trickling filters are two of the most common means of secondary
treatment. It is accomplished by bringing together waste, bacteria,
and oxygen in trickling filters or in the activated sludge
process. This treatment removes floating and settleable solids and
about 90 percent of the oxygen-demanding substances and suspended
solids. Disinfection is the final stage of secondary treatment.
septic tank--a tank used to detain domestic wastes to allow the settling of solids prior to distribution to a
leach field for soil absorption. Septic tanks are used when a sewer line is
not available to carry them to a treatment plant. A settling tank in which settled sludge is in immediate contact
with sewage flowing through the tank, and wherein solids are decomposed by anaerobic bacterial action.
sewer--a system of underground pipes that collect and deliver
wastewater to treatment facilities or streams.
somatic coliphage--a bacteriophage that infects coli
bacteria by attaching directly to the outer cell membrane or cell
wall. These coliphages are found in both animal and human feces and
are widely distributed in both polluted and unpolluted water.
Presence of coliphages has been found to correlate with the presence
of pathogenic virusus.
storm sewer--a sewer that carries only surface runoff, street wash, and snow melt from the land. In a
separate sewer system, storm sewers are completely separate from those that carry domestic and commercial
wastewater (sanitary sewers).
stream--a general term for a body of flowing water; natural water course containing water at least part of
the year. In hydrology, it is generally applied to the water flowing in a natural channel as distinct from a
canal.
streamflow--the water discharge that occurs in a natural channel. A more general term than runoff, streamflow may be applied
to discharge whether or not it is affected by diversion or regulation.
suspended sediment--very fine soil particles that
remain in suspension in water for a considerable period of time
without contact with the bottom. Such material remains in suspension
due to the upward components of turbulence and currents and/or by
suspension.
synoptic sampling--a type of sampling design which
attempts to collect water-quality data from many sites over a short
period of time to provide a "basin-wide snapshot" of water quality
conditions.
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T
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tertiary wastewater treatment--selected biological, physical, and chemical separation processes
to remove organic and inorganic substances that resist conventional treatment practices; the additional
treatment of effluent beyond that of primary and secondary treatment methods to obtain a very high quality of
effluent. The complete wastewater treatment process typically involves a three-phase process: (1) First, in the
primary wastewater treatment process, which incorporates physical aspects, untreated water is passed
through a series of screens to remove solid wastes; (2) Second, in the secondary wastewater treatment
process, typically involving biological and chemical processes, screened wastewater is then passed a series of
holding and aeration tanks and ponds; and (3) Third, the tertiary wastewater treatment process consists of
flocculation basins, clarifiers, filters, and chlorine basins or ozone or ultraviolet radiation processes.
total coliforms--gram-negative, aerobic or faculative
anaerobic, nonspore forming rods. These bacteria were originally
believed to indicate the presence of fecal contamination, however
total coliforms have been found to be widely distributed in nature and
not always associated with the gastrointestinal tract of warm blooded
animals. The number of total coliform bacteria in the environment is
still widely used as an indicator for potable water in the U.S.
tributary stream--a stream which joins another stream
or body of water or a stream or other body of water, surface or
underground, which contributes its water, even though intermittently
and in small quantities, to another and larger stream or body of
water.
turbidity--a measure of the scattering effect that
suspended solids have on light. Usually measured in nephelometric
turbidity units (NTUs) by passing light of a specific wavelength
through a sample, measuring the amount of light that is scattered, and
comparing this value to value scattered from a standard of known
turbidity.
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W
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wastewater--water that has been used in homes, industries, and businesses
that is not for reuse unless it is treated.
wastewater-treatment plant--a facility designed to receive the wastewater from domestic sources and to
remove materials that damage water quality and threaten public health and safety when discharged into
receiving streams or bodies of water. The substances removed are classified into four basic areas:
[1] greases and fats;
[2] solids from human waste and other sources;
[3] dissolved pollutants from human waste and decomposition products; and
[4] dangerous microorganisms.
Most facilities employ a combination of mechanical removal steps and bacterial decomposition to achieve the
desired results. Chlorine is often added to discharges from the plants to reduce the danger of spreading
disease by the release of pathogenic bacteria.
See primary,secondary
and tertiary wastewater treatment.
wastewater-treatment return flow--water returned to the environment by wastewater-treatment facilities.
water quality--a term used to describe the chemical, physical, and biological
characteristics of water, usually in respect to its
suitability for a particular purpose.
watershed--the portion of the surface of the earth
that contributes to a stream through overland run-off, including
tributaries and impoundments.
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