Glossary of Water Resource
- abandoned water right
- a water right which was not put to beneficial use
for a number of years, generally five to seven years.
- abandoned well
- a well which is no longer used. In many places,
abandoned wells must be filled with cement or concrete grout to prevent
pollution of ground water bodies.
- to take in.
- a gradual increase in land area adjacent to a
- acid rain
- the acidic rainfall which results when rain
combines with sulfur oxides emissions from combustion of fossil fuels.
- the amount of water required to cover one acre to
a depth of one foot. An acre-foot equals 325,851 gallons, or 43,560
cubic feet. A flow of 1 cubic
feet per second produce 1.98 acre-feet per
- activated carbon adsorption
- the process of pollutants moving out of water and
attaching on to activated carbon.
- the molecular attraction asserted between the
surfaces of bodies in contact. Compare
- a court proceeding to determine all rights to the
use of water on a particular stream system or ground water basin.
- the adhesion of a substance to the surface of a
solid or liquid. Adsorption is often used to extract pollutants by
causing them to be attached to such adsorbents as activated carbon or
silica gel. Hydrophobic, or water-repulsing adsorbents, are used to
extract oil from waterways in oil spills.
- the mixing or turbulent exposure of water to air
and oxgen to dissipate volatile contaminants and other pollutants into
- aggressive water
- water which is soft and acidic and can corrode
plumbing, piping, and appliances.
- the measurement of constituents in a water supply
which determine alkaline conditions. The alkalinity of water is a
measure of its capacity to neutralize acids. See
- algal bloom
- a phenomenon whereby excessive nutrients within a
river, stream or lake cause an explosion of plant life which results in
the depletion of the oxygen in the water needed by fish and other
aquatic life. Algae bloom is usually the result of urban runoff (of lawn
fertilizers, etc.). The potential tragedy is that of a "fish kill,"
where the stream life dies in one mass extinction.
- sediments deposited by erosional processes,
usually by streams.
- a sudden or perceptible change in a river's
margin, such as a change in course or loss of banks due to flooding.
- annular space
- the space between two concentric cylindrical
objects, one of which surrounds the other, such as the space between the
walls of a drilled hole and a casing.
- growing in, living in, or frequenting water.
- a formation which, although porous and capable of
absorbing water slowly, will not transmit water fast enough to furnish
an appreciable supply for a well or a spring.
- sediments deposited by erosional processes,
usually by streams .
- the raising or fattening of fish in enclosed
- a geologic formation that will yield water to a
well in sufficient quantities to make the production of water from this
formation feasible for beneficial use; permeable layers of underground
rock or sand that hold or transmit groundwater below the water table.
- artesian aquifer
- a geologic formation in which water is under
sufficient hydrostatic pressure to be discharged to the surface without
- artesian well
- a water well drilled into a confined aquifer
where enough hydraulic pressure exists for the water to flow to the
surface without pumping.
- artesian zone
- a zone where water is confined in an aquifer
under pressure so that the water will rise in the well casing or drilled
hole above the bottom of the confining layer overlying the aquifer.
- average annual recharge
- amount of water entering the aquifer on an
average annual basis. Averages mean very little for the Edwards because
the climate of the region and structure of the aquifer produce a
situation in which the area is usually water rich or water poor.
- reverse seepage of water in a distribution system.
- reversing the flow of water through a home
treatment device filter or membrane to clean and remove deposits.
- any artificial obstruction placed in water to
increase water level or divert it. Usually the idea is to control peak
flow for later release.
- beneficial use
- the amount of water necessary when reasonable
intelligence and diligence are used for a stated purpose; Texas law
recognizes the following uses as beneficial: (1) domestic and municipal
uses, (2) industrial uses, (3) irrigation, (4) mining, (5) hydroelectric
power, (6) navigation, (7) recreation, (8) stock raising, (9) public
parks, and (10) game preserves.
- uptake and retention of substances by an organism
from its surrounding medium (usually water) and from food.
- a test used to evaluate the relative potency of a
chemical by comparing its effect on a living organism with the effect of
a standard population on the same type of organism.
- a process that uses living organisms to remove pollutants.
- a nutrient-rich organic material resulting from
the treatment of wastewater. Biosolids contain nitrogen and phosphorus
along with other supplementary nutrients in smaller doses, such as
potassium, sulfur, magnesium, calcium, copper and zinc. Soil that is
lacking in these substances can be reclaimed with biosolids use. The
application of biosolids to land improves soil properties and plant
productivity, and reduces dependence on inorganic fertilizers.
- the earth and all its ecosystems
- wastewater from toilet, latrine, and agua privy
flushing and sinks used for food preparation or disposal of chemical or
- water samples containing a chemical of known
concentration given a fictitious company name and slipped into the
sample flow of the lab to test the impartiality of the lab staff.
- the water drawn from boiler systems and cold
water basins of cooling towers to prevent the buildup of solids.
- a type of wetland that accumulates appreciable
peat deposits. They depend primarily on precipitation for their water
source, and are usually acidic and rich in plant matter with a
conspicuous mat or living green moss.
- boiling point
- the temperature at which a liquid boils. It is
the temperature at which the vapor pressure of a liquid equals the
pressure on its surface. If the pressure of the liquid varies, the
actual boiling point varies. For water it is 212 degrees Fahrenheit or
100 degrees Celsius.
- Biochemical Oxygen Demand. A measure of the
amount of oxygen required to neutralize organic wastes.
- highly salty and heavily mineralized water
containing heavy metal and organic contaminants.
- the tendency of a body to float or rise when
immersed in a fluid; the power of a fluid to exert an upward force on a
body placed in it.
- calcium carbonate
- CACO3 - a white precipitate that forms in water
lines, water heaters and boilers in hard water areas; also known as
- amount of energy required to raise the
temperature of 1 gram of water 1 degree Celsius.
- capillary zone
- soil area above the water table where water can
rise up slightly through the cohesive force of capillary action. See
- a class of new-age pesticides that attack the
nervous system of organisms.
- the collective term for the natural inorganic
chemical compounds related to carbon dioxide that exist in natural
- a tubular structure intended to be watertight
installed in the excavated or drilled hole to maintain the well opening
and, along with cementing, to confine the ground waters to their zones
of origin and prevent the entrance of surface pollutants.
- a large underground opening in rock (usually
limestone) which occurred when some of the rock was dissolved by water.
In some igneous rocks, caverns can be formed by large gas bubbles.
- cement grout
- a mixture of water and cement in the ratio of not
more than 5-6 gallons of water to a 94 pound sack of portland cement
which is fluid enough to be pumped through a small diameter pipe.
- Comprehensive Environment Response, Compensation
and Liability Act. Also known as SUPERFUND. The Act gave EPA the
authority to clean up abandoned, leaky hazardous waste sites.
- certificate of water right
- an official document which serves as court
evidence of a perfected water right.
- colony forming units.
- check dam
- a small dam constructed in a gully or other small
water course to decrease the streamflow velocity, minimize channel
erosion, promote deposition of sediment and to divert water from a
- attack and dissolving of parent rock by exposure
to rainwater, surface water, oxygen, and other gases in the atmosphere,
and compounds secreted by organisms. Contrast
- the adding of chlorine to water or sewage for the
purpose of disinfection or other biological or chemical results.
- chlorine demand
- the difference between the amount of chlorine
added to water, sewage, or industrial wastes and the amount of residual
chlorine remaining at the end of a specific contact period. Compare
- chute spillway
- the overall structure which allows water to drop
rapidly through an open channel without causing erosion. Usually
constructed near the edge of dams.
- to move in a circle, circuit or orbit; to flow
without obstruction; to follow a course that returns to the starting
- a tank used to collect rainwater runoff from the
roof of a house or building.
- climatic cycle
- the periodic changes climate displays, such as a
series of dry years following a series of years with heavy rainfall.
- climatic year
- a period used in meteorological measurements. The
climatic year in the U.S. begins on October 1.
- generalized weather at a given place on earth
over a fairly long period; a long term average of weather. Compare
- a torrential downpour of rain, which by it
spottiness and relatively high intensity suggests the bursting and
discharge of water from a cloud all at once.
- in water treatment, the use of chemicals to make
suspended solids gather or group together into small flocs.
- a molecular attraction by which the particles of
a body are united throughout the mass whether like or unlike. Compare
- cold vapor
- method to test water for the presence of mercury.
- coliform bacteria
- non-pathogenic microorganisms used in testing
water to indicate the presence of pathogenic bacteria.
- collector well
- a well located near a surface water supply used
to lower the water table and thereby induce infiltration of surface
water through the bed of the water body to the well..
- finely divided solids which will not settle but
which may be removed by coagulation or biochemical action.
- combined sewer
- a sewer system that carries both sanitary sewage
and stormwater runoff. When sewers are constructed this way, wastewater
treatment plants have to be sized to deal with stormwater flows and
oftentimes some of the water receives little or no treatment. Compare
- sealing off access of undesireable water to the
well bore by proper casing and/or cementing procedures.
- composite sample,
- a sample composed of two or more portions
collected at specific times and added together in volumes related to the
flow at time of collection. Compare
- amount of a chemical or pollutant in a particular
volume or weight of air, water, soil, or other medium.
- the change of state from a gas to a liquid.
- a natural or artificial channel through which
fluids may be conveyed.
- cone of depression
- natural depression in the water table around a
well during pumping.
- confined aquifer
- an aquifer that lies between two relatively
impermeable rock layers.
- confining bed or unit
- a body of impermeable or distinctly less
permeable material stratigraphically adjacent to one or more aquifers.
- confluent growth
- in coliform testing, abundant or overflowing
bacterial growth which makes accurate measurement difficult or
- conjunctive management
- integrated management and use of two or more
water resources, such as an aquifer and a surface water body.
- connate growth
- water trapped in the pore spaces of a sedimentary
rock at the time it was deposited. It is usually highly mineralized.
- to protect from loss and waste. Conservation of
water may mean to save or store water for later use.
- consolidated formation
- naturally occurring geologic formations that have
been lithified (turned to stone). The term is sometimes used
interchangeably with the term "bedrock." Commonly, these formations will
stand at the edges of a bore hole without caving.
- consumptive use
- the quantity of water not available for reuse.
Evapotranspiration, evaporation, incorporation into plant tissue, and
infiltration into groundwater are some of the reasons water may not be
available for reuse. Compare
- contact recreation
- activities involving a significant risk of
ingestion of water, such as wading by children, swimming, water skiing,
diving and surfing. Compare
- the introduction into water of sewage or other
foreign matter that will render the water unfit for its intended use.
- cooling tower
- large tower used to transfer the heat in cooling
water from a power or industrial plant to the atmosphere either by
direct evaporation or by convection and conduction.
- correlative rights
- rights that are coequal or that relate to one
another, so that any one owner cannot take more than his share.
- a small stream of water which serves as the
natural drainage course for a drainage basin. The term is relative
according to size. Some creeks in a humid region would be called rivers
if they occurred in an arid area.
- the top of a dam, dike, or spillway, which water
must reach before passing over the structure; the summit or highest
point of a wave; the highest elevation reached by flood waters flowing
in a channel.
- low flow conditions below which some standards do
not apply. The impacts of permitted discharges are analyzed at critical
- cubic foot per second (CFS)
- the rate of discharge representing a volume of
one cubic foot passing a given point during 1 second. This rate is
equivalent to approximately 7.48 gallons per second, or 1.98
- the portion of a stream or body of water which is
moving with a velocity much greater than the average of the rest of the
water. The progress of the water is principally concentrated in the
current. See thalweg.
- a structure of earth, rock, or concrete designed
to form a basin and hold water back to make a pond, lake, or reservoir.
- deionized water
- water free of inorganic chemicals.
- an alluvial deposit made of rock particles (sediment,
and debris) dropped by a stream as it enters a body of water.
- the number of units of something that will be
purchased at various prices at a point in time. Compare
- dental fluorosis
- disorder caused by excessive absorption of
fluorine and characterized by brown staining of teeth.
- something dropped or left behind by moving water,
as sand or mud.
- the process of salt removal from sea or brackish
- detection limit
- the lowest level that can be determined by a
specific analytical procedure or test method.
- consisting of or abounding in diatoms, a class of
unicellular or colonial algae having a silicified cell wall that
persists as a skeleton after death.
- diluting water
- distilled water that has been stabilized,
buffered, and aerated. Used in the BOD test.
- the volume of water that passes a given point
within a given period of time. It is an all-inclusive outflow term,
describing a variety of flows such as from a pipe to a stream, or from a
stream to a lake or ocean.
- a permit issued by a state or the federal
government to discharge effluent into waters of the state or the United
States. In many states both State and federal permits are required.
- the killing of the larger portion of the harmful
and objectionable bacteria in the sewage. Usually accomplished by
introduction of chlorine, but more and more facilities are using
exposure to ultraviolet radiation, which renders the bacteria sterile.
- disinfection byproducts
- halogenated organic chemicals formed when water
- the movement and spreading of contaminants out
and down in an aquifer.
- distance by which portions of the same geological
layer are offset from each other by a fault.
- the process by which solid particles mix molecule
by molecule with a liquid and appear to become part of the liquid.
- dissolved oxygen (DO)
- amount of oxygen gas dissolved in a given
quantity of water at a given temperature and atmospheric pressure. It is
usually expressed as a concentration in parts per million or as a
percentage of saturation.
- dissolved solids
- inorganic material contained in water or wastes.
Excessive dissolved solids make water unsuitable for drinking or
industrial uses. See TDS.
- water treatment method where water is boiled to
steam and condensd in a separate reservoir. Contaminants with higher
boiling points than water do not vaporize and remain in the boiling
- distilled water
- water that has been treated by boiling and
condensation to remove solids, inorganics, and some organic chemicals.
- to remove water from a water body. Diversions may
be used to protect bottomland from hillside runoff, divert water away
from active gullies, or protect buildings from runoff.
- drainage area
- of a stream at a specified location is that area,
measured in a horizontal plane, enclosed by a topographic divide from
which direct surface runoff from precipitation normally drains by
gravity into the stream above the specified location.
- driller's well log
- a log kept at the time of drilling showing the
depth, thickness, character of the different strata penetrated, location
of water-bearing strata, depth, size, and character of casing installed.
- deposits of calcium carbonate that include stalactites, stalagmites,
columns, and cave pearls.
- although there is no universally accepted
definition of drought, it is generally the term applied to periods of
less than average precipitation over a certain period of time. In south
Texas ranchers say drought begins as soon as it stops raining.
- two separate samples with separate containers
taken at the same time at the same place.
- total of all the ecosystems on the planet, along
with their interactions; the sphere of air, water, and land in which all
life is found.
- Edwards Aquifer
- an arch-shaped belt of porous, water bearing
limestones composed of the Comanche Peak, Edwards, and Georgetown
formations trending from west to east to northeast through Kinney,
Uvalde, Medina, Bexar, Comal, Hays, Travis, and Williamson counties.
- Edwards outcrop
- where the Edwards and associated limestone
formations are found at the surface. This area is also referred to as
the Recharge Zone.
- effective porosity
- the portion of pore space in saturated permeable
material where the movement of water takes place.
- effective precipitation
- the part of precipitation which produces runoff;
a weighted average of current and antecedent precipitation "effective"
in correlating with runoff. It is also that part of the precipitation
falling on an irrigated area which is effective in meeting the
requirements of consumptive use.
- any substance, particularly a liquid, that enters
the environment from a point source. Generally refers to wastewater from
a sewage treatment or industrial plant.
- a process which uses an electrical current and an
arrangement of permeable membranes to separate soluble minerals from
water. It is often used to desalinate salt or brackish water.
- endangered species
- one having so few individual survivors that the
species could soon become extinct in all or part of its region.
- enteric viruses
- a category of viruses related to human excreta
found in waterways.
- aggregate of external conditions that influence
the life of an individual organism or population.
- Environmental Protection Agency
- warm, less dense top layer in a stratified lake.
- the wearing away of the land surface by wind,
water, ice or other geologic agents. Erosion occurs naturally from
weather or runoff but is often intensified by human land use practices.
- the topographic expression of a fault.
- estuarine waters
- deepwater tidal habitats and tidal wetlands that
are usually enclosed by land but have access to the ocean and are at
least occasionally diluted by freshwater runoff from the land (such as
bays, mouths of rivers, salt marshes, lagoons).
- estuarine zone
- area near the coastline that consists of
estuaries and coastal saltwater wetlands.
- thin zone along a coastline where freshwater
system(s) and river(s) meet and mix with a salty ocean (such as a bay,
mouth of a river, salt marsh, lagoon).
- euphotic zone
- surface layer of an ocean, lake, or other body of
water through which light can penetrate. Also known as the zone of
- having a large or excessive supply of plant
nutrients (nitrates and phosphates). Compare
- an excess of plant nutrients from natural erosion
and runoff from the land in an aquatic ecosystem supporting a large
amount of aquatic life that can deplete the oxygen supply.
- the change by which any substance is converted
from a liquid state and carried of in vapor. Compare
- combination of evaporation and transpiration of
water into the atmosphere from living plants and soil. Distinguish
- external cost
- cost of production or consumption that must be
borne by society; not by the producer.
- complete disappearance of a species because of
failure to adapt to environmental change.
- fecal coliform
- the portion of the coliform bacteria group which
is present in the intestinal tracts and feces of warm-blooded animals. A
common pollutant in water.
- a type of wetland that accumulates peat deposits,
but not as much as a bog.
Fens are less acidic than bogs, deriving most of their water from
groundwater rich in calcium and magnesium.
- fermentation, anaerobic
- process in which carbohydrates are converted in
the absence of oxygen to hydrocarbons (such as methane).
- field capacity
- the amount of water held in soil against the pull
- a device used to remove solids from a mixture or
to separate materials. Materials are frequently separated from water
- the mechanical process which removes particulate
matter by separating water from solid material, usually by passing it
- "first in
time, first in right"
- phrase indicating that older water rights have
priority over more recent rights if there is not enough water to satisfy
- fixed ground water
- water held in saturated material that it is not
available as a source of water for pumping.
- large scale treatment process involving gentle
stirring whereby small particles in flocs are collected into larger
particles so their weight causes them to settle to the bottom of the
- an overflow or inundation that comes from a river
or other body of water and causes or threatens damage. It can be any
relatively high streamflow overtopping the natural or artificial banks
in any reach of a stream. It is also a relatively high flow as measured
by either gage height or discharge quantity.
- land next to a river that becomes covered by
water when the river overflows its banks .
- plant population of a region.
- the rate of water discharged from a source
expressed in volume with respect to time.
- the addition of water to meet flow needs.
- the water behind a dam.
- forfeited water right
- a water right canceled because of several
consecutive years of nonuse.
- free ground water
- water in interconnected pore spaces in the zone
of saturation down to the first impervious barrier, moving under the
control of the water table slope.
- the change of a liquid into a solid as
temperature decreases. For water, the freezing point is 32 F or 0 C.
- fresh water
- water containing less than 1,000 parts per
million (ppm) of dissolved solids of any type. Compare
- fresh:salt water interface
- the region where fresh water and salt water meet.
In the Edwards region, it is commonly referred to as the "bad water line",
although it is zone and not a line.
- a covering of minute ice crystals on a cold
- gaging station
- the site on a stream, lake or canal where
hydrologic data is collected.
- A unit of volume. A U.S. gallon contains 231
cubic inches, 0.133 cubic feet, or 3.785 liters. One U.S. gallon of
water weighs 8.3 lbs.
- a term which denotes the branch of hydrology
relating to subsurface or subterranean waters; that is, to all waters
below the surface.
- geologic erosion
- normal or natural erosion caused by geological
processes acting over long geologic periods and resulting in the wearing
away of mountains, the building up of floodplains, coastal plains, etc.
- geopressured reservoir
- a geothermal reservoir consisting of porous sands
containing water or brine at high temperature or pressure.
- a periodic thermal spring that results from the
expansive force of super heated steam..
- a huge mass of land ice that consists of
recrystallized snow and moves slowly downslope or outward.
- grab sample
- a sample taken at a given place and time. Compare
- granular activated carbon
- pure carbon heated to promote "active" sites
which can adsorb pollutants. Used in some home water treatment systems
to remove certain organic chemicals and radon.
- wastewater from clothes washing machines, showers,
bathtubs, handwashing, lavatories and sinks that are not used for
disposal of chemical or chemical-biological ingredients.
- water within the earth that supplies wells and
springs; water in the zone of saturation where all openings in rocks and
soil are filled, the upper surface of which forms the water table.
- groundwater hydrology
- the branch of hydrology that deals with
groundwater; its occurrence and movements, its replenishment and
depletion, the properties of rocks that control groundwater movement and
storage, and the methods of investigation and utilization of ground
- groundwater law
- the common law doctrine of riparian rights and
the doctrine of prior appropriation as applied to ground water.
- groundwater recharge
- the inflow to a ground water reservoir.
- groundwater reservoir
- an aquifer or aquifer system in which ground
water is stored. The water may be placed in the aquifer by artificial or
- groundwater runoff
- the portion of runoff which has passed into the
ground, has become ground water, and has been discharged into a stream
channel as spring or seepage water.
- groundwater storage
- the storage of water in groundwater reservoirs.
- a deeply eroded channel caused by the
concentrated flow of water.
- gully reclamation
- use of small dams of manure and straw; earth,
stone,or concrete to collect silt and gradually fill in channels of
- a form of precipitation which forms into balls or
lumps of ice over 0.2 inch in diameter. Hail is formed by alternate
freezing and melting as precipitation is carried up and down in highly
turbulent air currents.
- a shallow layer of earth material which has
become relatively hard and impermeable, usually through the deposition
of minerals. In the Edwards region hardpans of clay are common.
- hard water
- water containing a high level of calcium,
magnesium, and other minerals. Hard water reduces the cleansing power of
soap and produces scale in hot water lines and appliances.
- hardness (water)
- condition caused by dissolved salts of calcium,
magnesium, and iron, such as bicarbonates, carbonates, sulfates,
- the pressure of a fluid owing to its elevation,
usually expressed in feet of head or in pounds per square inch, since a
measure of fluid pressure is the height of a fluid column above a given
or known point.
- the gate that controls water flow into irrigation
canals and ditches. A watermaster regulates the headgates during water
distribution and posts headgate notices declaring official regulations.
- heat of vaporization
- the amount of heat necessary to convert a liquid
(water) into vapor.
- heavy water
- water in which all the hydrogen atoms have been
replaced by deuterium.
- holding pond
- a small basin or pond designed to hold sediment
laden or contaminated water until it can be treated to meet water
quality standards or be used in some other way.
- hydroelectric plant
- electric power plant in which the energy of
falling water is used to spin a turbine generator to produce electricity.
- a chart that measures the amount of water flowing
past a point as a function of time.
- hydrologic cycle
- natural pathway water follows as it changes
between liquid, solid, and gaseous states; biogeochemical cycle that
moves and recycles water in various forms through the ecosphere. Also
called the water cycle.
- hydrologic unit
- is a geographic area representing part or all of
a surface drainage basin or distinct hydrologic feature.
- an instrument used to measure the density of a
- electrical energy produced by falling water.
- hygroscopic nuclei
- piece of dust or other particle around which
water condenses in the atmophere. These tiny droplets then collide and
coalesce, with as many as 10,000 nuclei contributing to formation of a
- region that includes all the earth's liquid water,
frozen water, floating ice, frozen upper layer of soil, and the small
amounts of water vapor in the Earth's atmosphere.
- hydrostatic head
- a measure of pressure at a given point in a
liquid in terms of the vertical height of a column of the same liquid
which would produce the same pressure.
- hydrostatic pressure
- pressure exerted by or existing within a liquid
at rest with respect to adjacent bodies.
- bottom layer of cold water in a lake. Compare
- a solid form of water.
- material that does not permit fluids to pass
- the quality or state of being impermeable;
resisting penetration by water or plant roots. Impervious ground cover
like concrete and asphalt affects quantity and quality of
- a body of water such as a pond, confined by a dam,
dike, floodgate or other barrier. It is used to collect and store water
for future use.
- inchoate water right
- an unperfected water right.
- indicator organisms
- microorganisms, such as coliforms, whose presence
is indicative of pollution or of more harmful microorganism.
- indicator tests
- tests for a specific contaminant, group of
contaminants, or constituent which signals the presence of something
else (ex., coliforms indicate the presence of pathogenic bacteria).
- inland freshwater wetlands
- swamps, marshes, and bogs found inland beyond the
coastal saltwater wetlands.
- instream use
- use of water that does not require withdrawal or
diversion from its natural watercourse; for example, the use of water
for navigation, recreation, and support of fish and wildlife.
- interbasin transfer
- the physical transfer of water from one watershed
to another; regulated by the Texas Water Code.
- intermittent stream
- one that flows periodically. Compare
- interstate water
- according to law, interstate waters are defined
as (1) rivers, lakes and other waters that flow across or form a part of
state or international boundaries; (2) waters of the Great Lakes; (3)
coastal waters whose scope has been defined to include ocean waters
seaward to the territorial limits and waters along the coastline (including
inland streams) influenced by the tide.
- the void or empty portion of rock or soil
occupied by air or water.
- irrigation efficiency
- the percentage of water applied, and which can be
accounted for, in the soil moisture increase for consumptive use.
- irrigation return flow
- water which is not consumptively used by plants
and returns to a surface or ground water supply. Under conditions of
water right litigation, the definition may be restricted to measurable
water returning to the stream from which it was diverted.
- water which is applied to assist crops in areas
or during times where rainfall is inadequate.
- line that connects points of equal temperature.
- line that connects points of equal rainfall.
- jet stream
- a long narrow meandering current of high-speed
winds near the tropopause blowing from a generally westerly direction
and often exceeding a speed of 250 miles per hour.
- a jet of water.
- one (as a geyser) that sends out a jet.
- a structure (as a pier or mole of wood or stone)
extending into a sea, lake, or river to influence the current or tide or
to protect a harbor.
- a violent surf that occurs on the coast of the
Guinea region, West Africa.
- a short ridge, hill, or mound of stratified drift
deposited by glacial meltwater.
- kame terrace
- a terrace of stratified sand and and gravel
deposited by streams between a glacier and an adjacent valley wall.
- laboratory water
- purified water used in the laboratory as a basis
for making up solutions or making dilutions. Water devoid of interfering
- lag time
- the time from the center of a unit storm to the
peak discharge or center of volume of the corresponding unit hydrograph.
- a shallow pond where sunlight, bacterial action,
and oxygen work to purify wastewater. Lagoons are typically used for the
storage of wastewaters, sludges, liquid wastes, or spent nuclear fuel.
- an inland body of water, usually fresh water,
formed by glaciers, river drainage etc. Usually larger than a pool or
- landscape impoundment
- body of reclaimed water which is used for
aesthetic enjoyment or which otherwise serves a function not intended to
include contact recreation.
- water containing contaminants which leaks from a
disposal site such as a landfill or dump.
- extraction or flushing out of dissolved or
suspended materials from the soil, solid waste, or another medium by
water or other liquids as they percolate down through the medium to
- lentic system
- a nonflowing or standing body of fresh water,
such as a lake or pond. Compare
- a natural or man-made earthen obstruction along
the edge of a stream, lake, or river. Usually used to restrain the flow
of water out of a river bank.
- rock that consists mainly of calcium carbonate
and is chiefly formed by accumulation of organic remains.
- limiting factor
- factor such as temperature, light, water, or a
chemical that limits the existence, growth, abundance, or distribution
of an organism.
- scientific study of physical, chemical, and
biological conditions in lakes, ponds, and streams.
- a state of matter, neither gas nor solid, that
flows and takes the shape of its container.
- littoral zone
- area on or near the shore of a body of water.
- lotic system
- a flowing body of fresh water, such as a river or
stream. Compare lentic
- cultivation of fish and shellfish in estuarine
and coastal areas.
- an area periodically inundated and treeless and
often characterized by grasses, cattails, and other monocotyledons
- MCL - Maximum Contaminant Level
- the maximum level of a contaminant allowed in
water by federal law. Based on health effects and currently available
- median streamflow
- the rate of discharge of a stream for which there
are equal numbers of greater and lesser flow occurrences during a
- the changing of a solid into a liquid.
- water that comes from the melting ice of a
glacier or a snowbank.
- meteoric water
- new water derived from the atmosphere.
- a fabled marine creature usually represented as
having the head, trunk, and arms of a woman and a lower part like the
tail of a fish.
- method blank
- laboratory grade water taken through the entire
analytical procedure to determine if samples are being accidentally
contaminated by chemicals in the lab
- micrograms per liter - Ug/L
- micrograms per liter of water. One thousands
micrograms per liter is equivalent to 1 milligram per liter. This
measure is equivalent to parts
per billion (ppb)
- the movement of oil, gas, contaminants, water, or
other liquids through porous and permeable rock.
- milligrams per liter - mg/L
- milligrams per liter of water. This measure is
equivalent to parts per million
- minimum streamflow
- the specific amount of water reserved to support
aquatic life, to minimize pollution, or for recreation. It is subject to
the priority system and does not affect water rights established prior
to its institution.
- municipal sewage
- sewage from a community which may be composed of
domestic sewage, industrial wastes or both.
- natural flow
- the rate of water movement past a specified point
on a natural stream. The flow comes from a drainage area in which there
has been no stream diversion caused by storage, import, export, return
flow, or change in consumptive use caused by man-controlled
modifications to land use. Natural flow rarely occurs in a developed
- natural resource
- any form of matter or energy obtained from the
environment that meets human needs.
- National Interim Primary Drinking Water
- a plant
nutrient that can cause
an overabundance of bacteria and algae when high amounts are present,
leading to a depletion of oxygen and fish kills. Several forms occur in
water, including ammonia, nitrate, nitrite or elemental nitrogen. High
levels of nitrogen in water are usually caused by agricultural runoff or
improperly operating wastewater treatment plants. Also see
- nonconsumptive use
- using water in a way that does not reduce the
supply. Examples include hunting, fishing, boating, water-skiing,
swimming, and some power production. Compare
- noncontact recreation
- recreational pursuits not involving a significant
risk of water ingestion, including fishing, commercial and recreational
boating, and limited body contact incidental to shoreline activity.
Compare contact recreation.
- something which does not allow water to pass
through it. Compare porous.
- nonpoint source
- source of pollution in which wastes are not
released at one specific, identifiable point but from a number of points
that are spread out and difficult to identify and control. Compare
- not suitable for drinking. Compare
- nonthreshold pollutant
- substance or condition harmful to a particular
organism at any level or concentration.
- NPDES permit
- permit issued under the National Pollutant
Discharge Elimination System for companies discharging pollutants
directly into the waters of the United States.
- nephlometric turbidity units.
- as a pollutant, any element or compound, such as
that fuels abnormally high organic growth in aquatic ecosystems. Also
- having a low supply of plant nutrients. Compare
- open system
- system in which energy and matter are exchanged
between the system and its environment, for example, a living organism.
- organic chemicals
- chemicals containing carbon.
- period of mountain-building.
- orographic precipitation
- rainfall that occurs as a result of warm, humid
air being forced to rise by topographic features such as mountains.
Precipitation on the Edwards Plateau is slightly higher because of the
orographic effect of the escarpment and hills.
- exposed at the surface. The Edwards limestone
outcrops in its recharge zone.
- the place where a wastewater treatment plant
discharges treated water into the environment.
- a deposit of sand and gravel formed by streams of
meltwater flowing from a glacier.
- oxygen demanding waste
- organic water pollutants that are usually
degraded by bacteria if there is sufficient dissolved oxygen (DO) in the
- microorganisms which can cause disease.
- peak flow
- in a wastewater treatment plant, the highest flow
expected to be encoutered under any operational conditions, including
periods of high rainfall and prolonged periods of wet weather.
- perched water table
- groundwater standing unprotected over a confined
- the movement of water through the subsurface soil
layers, usually continuing downward to the groundwater or water table
- percolating waters
- waters passing through the ground beneath the
Earth's surface without a definite channel.
- perfected water right
- a water right which indicates that the uses
anticipated by an applicant, and made under permit, were made for
beneficial use. Usually it is irrevocable unless voluntarily canceled or
forfeited due to several consecutive years of nonuse.
- perennial stream
- one that flows all year round. Compare
- the ability of a water bearing material to
transmit water. It is measured by the quantity of water passing through
a unit cross section, in a unit time, under 100 percent hydraulic
- numeric value that describes the intensity of the
acid or basic (alkaline) conditions of a solution. The pH scale is from
0 to 14, with the neutral point at 7.0. Values lower than 7 indicate the
presence of acids and greater than 7.0 the presence of alkalis (bases).
Technically speaking, pH is the logarithm of the reciprocal (negative
log) of the hydrogen ion concentration (hydrogen ion activity) in moles
- a plant
nutrient that can cause
an overabundance of bacteria and algae when high amounts are present,
leading to a depletion of oxygen and fish kills. High levels of
phosphorous in water are usually caused by agricultural runoff or
improperly operating wastewater treatment plants. Also see
- plants that send their roots into or below the
to use ground water.
- breaking down of parent rock into bits and pieces
by exposure to temperature and changes and the physical action of moving
ice and water, growing roots, and human activities such as farming and
- free-floating, mostly microscopic aquatic plants.
- piezometroc surface
- the imaginary surface to which groundwater rises
under hydrostatic pressure in wells or springs.
- microscopic floating plant and animal organisms
of lakes, rivers, and oceans.
- plate tectonics
- refers to the folding and faulting of rock and
flow of molten lava involving lithospheric plates in the earth's crust
and upper mantle.
- cement, grout, or other material used to fill and
seal a hole drilled for a water well.
- the area taken up by contaminant(s) in an
- pertaining to precipitation.
- point source
- source of pollution that involves discharge of
wastes from an identifiable point, such as a smokestack or sewage
treatment plant. Compare
- undesireable change in the physical, chemical, or
biological characteristics of the air, water, or land that can harmfully
affect the health, survival, or activities of human or other living
- a body of water usually smaller than a lake and
larger than a pool either naturally or artificially confined.
- something which allows water to pass through it.
- suitable, safe, or prepared for drinking. Compare
- ppb - parts per billion
- number of parts of a chemical found in one
billion parts of a solid, liquid, or gaseous mixture. Equivalent to
micrograms per liter
- ppm - parts per million
- number of parts of a chemical found in one
million parts of a solid, liquid, or gaseous mixture. Equivalent to
milligrams per liter
- a solid which has come out of an aqueous
solution. (ex., iron from groundwater precipitates to a rust colored
solid when exposed to air).
- a chemical added to a water sample to keep it
stable and prevent compounds in it from changing to other forms or to
prevent microorganism densities from changing prior to analysis.
- price at equilibrium
- where supply and demand curves intersect. The
price at equilibrium is what allocates resources.
- primary treatment
- mechanical treatment in which large solids are
screened out and suspended solids in the sewage settle out as sludge.
- priority date
- the date of establishment of a water right. It is
determined by adjudication of rights established before the passage of
the Water Code. The rights established by application have the
application date as the date of priority.
- profundal zone
- a lake's deep-water region that is not penetrated
- a small pool of water, usually a few inches in
depth and from several inches to several feet in its greatest dimension.
- a device which moves, compresses, or alters the
pressure of a fluid, such as water or air, being conveyed through a
natural or artificial channel.
- pumped hydroelectric storage
- storing water for future use in generating
electricity. Excess electrical energy produced during a period of low
demand is used to pump water up to a reservoir. When demand is high, the
water is released to operate a hydroelectric generator.
- to force a gas through a water sample to liberate
volatile chemicals or other gases from the water so their level can be
- purgeable organics
- volatile organic chemicals which can be forced
out of the water sample with relative ease through purging.
- quarry water
- the moisture content of freshly quarried stone,
esp. if porous.
- quicksilver water
- a solution of mercury nitrate used in gilding.
- the part of a stream that has a strong current;
an artificial current or bubbling patch of water just astern of a moving
- water drops which fall to the earth from the air.
- rain gage
- any instrument used for recording and measuring
time, distribution, and the amount of rainfall.
- Resource Conservation and Recovery Act - federal
legislation requiring that hazardous waste be tracked from "cradle"
(generation) to "grave" (disposal).
- receiving waters
- a river, ocean, stream, or other watercourse into
which wastewater or treated effluent is discharged.
- refers to water entering an underground aquifer
through faults, fractures, or direct absorption.
- recharge zone
- the area where a formation allows available water
to enter the aquifer. Generally, that area where the Edwards Aquifer and
associated limestones crop out in Kinney, Uvalde, Medina, Bexar, Comal,
Hays, Travis, and Williamson counties and the outcrops of other
formations in proximity to the Edwards limestone, where faulting and
fracturing may allow recharge of the surface waters to the Edwards
- reclaimed water
- domestic wastewater that is under the direct
control of a treatment plant owner/operator which has been treated to a
quality suitable for a beneficial use.
- recurrence interval
- average amount of time between events of a given
magnitude. For example, there is a 1% chance that a 100-year flood will
occur in any given year.
- amount of a particular resource in known
locations that can be extracted at a profit with present technology and
- a pond, lake, tank, or basin (natural or human
made) where water is collected and used for storage. Large bodies of
groundwater are called groundwater reservoirs; water behind a dam is
also called a reservoir of water.
- residual chlorine
- the available chlorine which remains in solution
after the demand has been satisfied. Compare
- reverse osmosis
- a water treatment method whereby water is forced
through a semipermeable membrane which filters out impurities.
- right of free capture
- the idea that the water under a person's land
belongs to that person and they are free to capture and use as much as
they want. Also called the "law of the biggest pump".
- riparian water right
- the legal right held by an owner of land
contiguous to or bordering on a natural stream or lake, to take water
from the source for use on the contiguous land.
- riparian zone
- a stream and all the vegetation on its banks.
- a natural stream of water of considerable volume.
- river basin
- the area drained by a river and its tributaries.
- surface water entering rivers, freshwater lakes,
- saline water
- water containing more than 1,000 parts per
million (ppm) of dissolved solids of any type. Compare
- amount of dissolved salts in a given volume of
- sanitary landfill
- landfill that is lined with plastic or concrete or located in
clay-rich soils to prevent hazardous substances from leaking into the
- the condition of a liquid when it has taken into
solution the maximum possible quantity of a given substance at a given
temperature and pressure.
- the impermeable material, such as cement grout
bentonite, or puddling clay placed in the annular space between the
borehole wall and the casing of a water well to prevent the downhole
movement of surface water or the vertical mixing of artestian waters.
- second step in most waste treatment systems, in
which bacteria break down the organic parts of sewage wastes; usually
accomplished by bringing the sewage and bacteria together in trickling
filters or in the activated sludge process. Compare primary treatment,
tertiary treatment. Compare
- soil particles, sand, and minerals washed from
the land into aquatic systems as a result of natural and human
- sedimentary cycle
- biogeochemical cycle in which materials primarily
are moved from land to sea and back again.
- a large scale water treatment process where heavy
solids settle out to the bottom of the treatment tank after
- a spot where water contained in the ground oozes
slowly to the surface and often forms a pool; a small spring.
- separate sewer
- a sewer system that carries only sanitary sewage,
not stormwater runoff. When a sewer is constructed this way, wastewater
treatment plants can be sized to treat sanitary wastes only and all of
the water entering the plant receives complete treatment at all times.
- septic tank
- underground receptacle for wastewater from a
home. The bacteria in the sewage decopose the organic wastes, and the
sludge settles to the bottom of the tank. The effluent flows out of the
tank into the ground through drains.
- settleable solids
- in sewage, suspended solids that will settle when
the sewage is brought to a quiet state for a reasonable length of time,
usually two hours.
- the deposition of finely divided soil and rock
particles upon the bottom of stream and river beds and reservoirs.
- precipitation which is a mixture of rain and ice.
- a smooth striated polished surface produced on
rock by movement along a fault.
- solid matter that settles to the bottom of
sedimentation tanks in a sewage treatment plant and must be disposed of
by digestion or other methods or recycled to the land.
- precipitation in the form of branched hexagonal
crystals, often mixed with simple ice crystals, which fall more or less
continuously from a solid cloud sheet. These crystals may fall either
separately or in cohesive clusters forming snowflakes.
- any substance derived from the atmosphere,
vegetation, soil, or rock that is dissolved in water.
- soil erosion
- the processes by which soil is removed from one
place by forces such as wind, water, waves, glaciers, and construction
activity and eventually deposited at some new place.
- a measure of the ability of a water to conduct an
electrical current. Specific conductance is related to the type and
concentration of ions in solution and can be used for approximating the
dissolved solids concentration in water. In general, for the San Antonio
River basin, conductivity * .6 approximates TDS. People monitoring water
quality can measure electrical conductivity quickly in the field and
estimate TDS without doing any lab tests at all. See
- specific heat
- the amount of heat required to raise the
temperature of a kilogram of a substance (water) by 1 degree Celsius.
- the channel or passageway around or over a dam
through which excess water is diverted.
- spray irrigation
- application of finely divided water droplets to
crops using artificial means.
- an issue of water from the earth; a natural
fountain; a source of a body or reservoir of water.
- standard solution
- any solution in which the concentration is known.
- stormwater discharge
- precipitation that does not infiltrate into the
ground or evaporate due to impervious land surfaces but instead flows
onto adjacent land or water areas and is routed into drain/sewer
- a general term for a body of flowing water.
- stream segment
- refers to the surface waters of an approved
planning area exhibiting common biological, chemical, hydrological,
natural, and physical characteristics and processes. Segments will
normally exhibit common reactions to external stress such as discharge
- the discharge that occurs in a natural channel.
- the transition of water directly from the solid
state to the gaseous state, without passing through the liquid state; or
vice versa. Compare
- sinking down of part of the earth's crust due to
underground excavation, such as removal groundwater.
- a schedule that shows the various quantities of
things offered for sale at various prices at a point in time. Compare
- surface impoundment
- an indented area in the land's surface, such a
pit, pond, or lagoon.
- surface irrigation
- application of water by means other than spraying
such that contact between the edible portion of any food crop and the
irrigation water is prevented.
- surface water
- water that flows in streams and rivers and in
natural lakes, in wetlands, and in reservoirs constructed by humans.
- sustainable management
- method of exploiting a resource that can be
carried on indefinitely. Removal of water from an aquifer in excess of
recharge is, in the long term, not a sustainable management method.
- long term withdrawal from the aquifer of more
water than is being recharged.
- technology-based treatment requirements
- NPDES permit requirements based on the
application of pollution treatment or control technologies including BTP
(best practicable technology), BCT (best conventional technology), BAT
(best available technology economically achievable), and NSPS (new
source performance standards).
- tertiary treatment
- removal from wastewater of traces or organic
chemicals and dissolved solids that remain after
- the line of maximum depth in a stream. The
thalweg is the part that has the maximum velocity and causes cutbanks
and channel migration.
- thermal gradient
- temperature difference between two areas.
- thermal pollution
- an increase in air or water temperature that
disturbs the climate or ecology of an area.
- fairly thin zone in a lake that separates an
upper warmer zone (epilimnion) from a lower colder zone (hypolimnion).
- threshold pollutant
- substance that is harmful to a particular
organism only above a certain concentration, or threshold level.
- TDS - total dissolved solids
- the sum or all inorganic and organic particulate
material. TDS is an indicator test used for wastewater analysis and is
also a measure of the mineral content of bottled water and groundwater.
There is a relationship between TDS and conductivity. In general, for
the San Antonio River basin, TDS/.6 approximates conductivity. Or,
conductivity * .6 approximates TDS. People monitoring water quality can
measure electrical conductivity quickly in the field and estimate TDS
without doing any lab tests at all. See
- Toxicity Reduction Evaluation (TRE)
- a study conducted to determine the source(s) of
toxicity in a discharge effluent so that these sources can be controlled
sufficiently to allow a discharger to comply with their permit limits.
- toxicity test
- the means to determine the toxicity of a chemical
or an effluent using living organisms. A toxicity test measures the
degree of response of an exposed test organism to a specified chemical
- Tragedy of the Commons
- the idea that no one takes responsibility for
things that everybody owns.
- refers to the rate at which limestone allows the
transmission of water. Limestone can be highly porous, but not very
transmissive if the pores are not connected to each other. Technically
speaking, it is the rate at which water is transmitted through a unit
width of aquifer under unit hydraulic gradient. Transmissivity is
directly proportional to aquifer thickness, thus it is high where the
Edwards is thick and low where it is thin, given the same hydraulic
- direct transfer of water from the leaves of
living plants to the atmosphere. Distinguish
- a stream that contributes its water to another
stream or body of water.
- thick or opaque with matter in suspension. Rivers
and lakes may become turbid after a rainfall.
- the layer of atmosphere closest to the Earth,
extending seven to ten miles above the surface, containing most of the
clouds and moisture.
- United States Geological Survey
- unclassified waters
- those waters for which no classification has been
assigned and which have not been identified in Appendix A of 31 Texas
Administrative Code, Chapter 307.10 of Title 31 (relating to
- unconsolidated formations
- naturally occurring earth formations that have
not been lithified. Alluvium, soil, gravel, clay, and overburden are
some of the terms used to describe this type of formation.
- a current below the upper currents or surface of
a fluid body.
- a concealed drain with openings through which the
water enters when the water table reaches the level of the drain.
- movement of water through subsurface material.
- the current beneath the surface that sets seaward
or along the beach when waves are breaking on the shore.
- under the surface of the water; lying, growing,
performed, worn, or operating below the surface of the water, as
underwater caverns, underwater operation of a submarine.
- an upward flow.
- vested water right
- the right granted by a state water agency to use
either surface or ground water.
- virgin flow
- the streamflow which exists or would exist if man
had not modified the conditions on or along the stream or in the
- the pore space or other openings in rock. The
openings can be very small to cave size and are filled with water below
the water table.
- water containing waste including greywater,
blackwater or water contaminated by waste contact, including
process-generated and contaminated rainfall runoff.
- the liquid that descends from the clouds as rain;
forms streams, lakes, and seas, and is a major constituent of all living
matter. It is an odorless, tasteless, colorless, very slightly
- water cycle
- natural pathway water follows as it changes
between liquid, solid, and gaseous states; biogeochemical cycle that
moves and recycles water in various forms through the ecosphere. Also
called the hydrologic cycle.
- water pollution
- degradation of a body of water by a substance or
condition to such a degree that the water fails to meet specified
standards or cannot be used for a specific purpose.
- water quality-based toxics control
- an integrated strategy used in NPDES permitting
to assess and control the discharge of toxic pollutants to surface
waters. There are two approaches: the whole-effluent approach involves
the use of toxicity tests to measure discharge toxicity; the chemical
specific approach involves the use of water quality criteria or State
standards to limit specific toxic pollutants directly.
- water quality criteria
- scientifically derived ambient limits developed
and updated by EPA, under section 304(a)(1) of the Clean Water Act, for
specific pollutants of concern. Criteria are recommended concentrations,
levels, or narrative statements that should not be exceeded in a
waterbody in order to protect aquatic life or human health.
- water quality standards
- laws or regulations, promulgated under Section
303 of the Clean Water Act, that consist of the designated use or uses
of a waterbody or a segment of a waterbody and the water quality
criteria that are necessary to protect the use or uses of that
particular waterbody. Water quality standards also contain an
antidegradation statement. Every State is required to develop water
quality criteria standards applicable to the various waterbodies within
the State and revise them every 3 yeaars.
- water table
- level below the earth's surface at which the
ground becomes saturated with water. The surface of an unconfined
aquifer which fluctuates due to seasonal precipitation.
- water table aquifer
- an aquifer confined only by atmospheric pressure
(water levels will not rise in the well above the confining bed).
- water well
- any artificial excavation constructed for the
purpose of exploring for or producing ground water.
- water year
- The 12-month period, usually October 1 through
September 30. The water year is designated by the calendar year in which
it ends and which includes 9 of the 12 months. Thus, the year ending
September 30, 1998 is called the1998 Water Year.
- A sudden, nearly vertical drop in a stream, as it
flows over rock.
- saturation of soil with irrigation water so the
water table rises close to the surface.
- An employee of a water department who distributes
available water supply at the request of water right holders and
collects hydrographic data.
- land area from which water drains toward a common
watercourse in a natural basin.
- day to day variation in atmospheric conditions.
- area that is regularly wet or flooded and has a
water table that stands at or above the land surface for at least part
of the year, such as a bog,
- whole-effluent toxicity
- the aggregate toxic effect of an effluent
measured directly by a toxicity test.
- creative landscaping for water and energy
efficiency and lower maintenance. The seven xeriscape principles are:
good planning and design; practical lawn areas; efficient irrigation;
soil improvement; use of mulches; low water demand plants; good
- the quantity of water expressed either as a
continuous rate of flow (cubic feet per second, etc.) or as a volume per
unit of time. It can be collected for a given use, or uses, from surface
or groundwater sources on a watershed.
- zone of aeration
- a region in the Earth above the water table.
Water in the zone of aeration is under atmospheric pressure and will not
flow into a well.
- zone of saturation
- the space below the water table in which all the
interstices (pore spaces) are filled with water. Water in the zone of
saturation is called groundwater.
- tiny aquatic animals eaten by fish.