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Encyclopedia of Water Terms



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.

ABOVEGROUND STORAGE TANK : A non vehicular device (including any associated piping that is made of non earthen materials) located on or above the surface of the ground, or on or above the surface of the floor of a Structure below the ground, such as mineworking1 basement or vault; and designed to contain an accumulation of petroleum products.

ABSORB: To take in. Many things absorb water.

ACID MINE WASTE: One of the principal pollutants arising from mining operations. Acid water forms when water contacts certain types of exposed mine wastes and ores.

ACID RAIN: The acidic rainfall which results when rain combines with sulfur oxides emissions from combustion of fossil fuels (coal).

ACID: A chemical compound which dissolves in water. Acids have sour taste and turn a vegetable dye called litmus, red. An acid separates into two or more electrically charged parts when it is dissolved in water.

ACRE FEET: The amount of water required to cover one acre one foot deep. Also abbreviated as ac-ft.

ACRE-FOOT: An expression of water quantity. One acre-foot will cover one acre of ground one foot deep. An acre-foot contains 43,560 cubic feet, 1,233 cubic meters, or 325,829 gallons (U.S.).

ACTIVE SOLAR HEATING : A space heating system in which heat from the sun is absorbed by collectors and transferred by pumps or fans to a storage unit for later use or to the house interior directly. Controls regulating the operation are needed.

ACTIVE SOLAR WATER HEATER: A water heating system in which heat from the sun is absorbed by collectors and transferred by pumps to a storage unit. The heated fluid in the storage unit conveys its heat to the domestic hot water of the house through a heat exchanger. Controls regulating the operation are needed.

ADJUDICATION: A court proceeding to determine all rights to the use of water on a particular stream system or ground water basin.

ADMINISTRATIVE ORDER ON CONSENT(AOC): A legal and enforceable agreement between EPA and the parties potentially responsible for site contamination. Under the terms of the Order, the potentially responsible parties(PRPs) agree to perform or pay for site studies or cleanups. It also describes the oversight rules, responsibilities and enforcement options that the government may exercise in the event of non-compliance by potentially responsible parties. This Order is signed by PRPs and the government; it does not require approval by a judge.

ADMINISTRAVTIVE RECORD: The collection of documents which forms the basis for the selection of a response action at a Superfund site. EPA is required to establish an administrative record file for every Superfund site and make a copy available at or near the site. Often, it is the local library near a Superfund site that keeps the administrative record on file for public reference.

ADSORPTION: 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.

AERATION: The process of bubbling air through a solution, sometimes cleaning water of impurities by exposure to the air.

AGRICULTURAL BY-PRODUCTS: Products developed in agriculture that are not the primary goal of the agricultural activity. Some of these are being used as building materials. An example is straw used to make wall panels, or as bales in a technique called straw bale construction.

AGRICULTURAL FIBER: Agricultural fibers (i.e., cotton) are being introduced for use as insulation materials.

ALGAE BLOOM: A phenomenon whereby excessive nutrients within a river, stream or lake causes 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.

ALKALINE: Sometimes water or soils contain an AMBIENT: The natural conditions that would be expected to occur in water unaffected or not influenced by the activities of man.

AMPOULES: Sealed, liquid-filled tube which is broken to release or be filled with another fluid.

APPLICATION, WATER RIGHT: An official request for permission to initiate a water right; includes a description of the proposed project, a map of the project and a legal description of the property involved.

APPROPRIATE: To authorize the use of a quantity of water to an individual requesting it.

APPURTENANT TO PLACE OF USE: A water right that belongs to the legal owner of the land described as the place of use on the water right.

AQUA: Prefix meaning water.

AQUATIC LIFE: All forms of living things found in water, ranging from bacteria, to fish and rooted plants. Insect larva and zooplankton are also included.

AQUEDUCT: A pipe or conduit made for bringing water from a source.

AQUICLUDE: 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.

AQUIFER: A water bearing stratum of permeable rock, sand, or gravel.

ARID: An adjective applied to regions where precipitation is deficient in quantity; where agriculture is impractical without irrigation.

ARIDITY: The quality or state of being arid, dry or barren.

ARTESIAN AQUIFER: An aquifer where the water is under sufficient head (pressure) to cause it to rise above the zone of saturation if the opportunity were afforded for it to do so.

ARTESIAN WATER: Water that comes from artesian wells.

ARTESIAN WELL: A well tapping a confined or artesian aquifer in which the static water level stands above the top of the aquifer. The term is sometimes used to include all wells tapping confined water. Wells with water level above the water table are said to have positive artesian head, (pressure) and those with water level below the water table, negative artesian head.

ARTESIAN WALL: A well made by drilling into the earth until water is reached which, from internal pressure, flows up like a fountain.

As: Arsenic.

ASBESTOS: A mineral fiber that had been commonly used in many building construction materials for insulation and as a fireÑretardant. Invisible fibers of asbestos can be inhaled and have been connected to lung diseases and cancer.

ASSESSMENT REPORT: A comprehensive record of historical, existing and projected water quality conditions of a watershed.

ASSIGNMENT OF WATER: The transfer of a water right application or permit from one person to another. This can be done in conjunction with the sale of land.

ATMOSPHERE: The air. The layer of gases surrounding the earth and composed of considerable hydrogen and oxygen, and when properly combined, water.

ATTACHED GROUND WATER: The portion of amount of alkali substances sufficient to raise the pH value above 7.0 or to be harmful to the growth of crops. Such a condition is called alkaline.

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BACKFILL: To refill an excavated area with removed earth; or the material itself that is used to refill an excavated area.

BENEFICIAL USE OF WATER: The use of water for any beneficial purpose. Such uses include domestic use, riigation, recreation, fish and wildlife, fire protection, navigation, power, industrial use, etc. The benefit varies from one location to another and by custom. What constitutes beneficial use is often defined by statute or court decisions.

BEST MANAGEMENT PRACTICE: A practice or combination of practices determined to be the most practicable means of preventing or reducing, to a level compatible with water quality goals, the amount of pollution generated by nonpoint sources.

BIOCHEMICAL OXYGEN DEMAND: The oxygen used in meeting the metabolic needs of aerobic microorganisms in water rich in organic matter.

BIODEGRADATION: The technology that uses microorganisms to degrade contaminants.

BIOSPHERE: The part of the world in which life can exist.

BIOTA: All the species of plants and animals indigenous to a certain area.

BLOWDOWN: The water drawn from boiler systems and cold water basins of cooling towers to prevent the buildup of solids.

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.

BOILING WATER REACTOR (BWR): A nuclear reactor in which water, used as both coolant and moderator, is allowed to boil in the core. The resulting steam can be used directly to drive a turbine generating electric power.

BORATE-TREATED WOOD: Borate is a mineral product derived from borax. Treating wood with borates has been done in New Zealand and Australia for many years (for insect and moisture protection). Commercial applicability' is being researched in the U.S. with a major effort geared toward preventing the borates from leaching out in the presence of moisture. Borates are commonly used to treat cellulose insulation.

BORROW PIT: An excavated area where soil, sand, or gravel has been dug up for use elsewhere.

BRINE: Water that is saturated or partially saturated with salt.

BUFFER STRIP or ZONE: Strips of grass or other erosion resistant vegetation between a waterway and an area of more intensive land use.

BUILT ENVIRONMENT: All human-built-structures. In the GREEN BUILDER PROGRAM, the built environment pertains to single-family-homes only.

BUOYANCY: 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.

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C - Carbon.

CALIBRATION: Fine tuning of an instrument to meet a specific standard value. This helps to ensure data accuracy.

CALICHE: Calcium carbonate in earth, common to semi-arid parts of Central - Texas. It makes an especially hard brick without firing and is a common roadbed material. It is not commercially available at this time as a brick. However, small manufacturing operations previously have been set up in Central Texas for special projects.

CALORIE(cal.): This word has more than one definition. A calorie is a unit of heat energy equal to the amount of heat needed to raise the temperature of one gram water one degree Celsius. The calorie is used when temperature is measured on the Celsius scale. The British Thermal Unit is used when the measurement is on the Fahrenheit scale. One calorie equals 4.14 joules. A calorie is also the amount of food which contains the energy producing value of one calorie.

CANCELLED WATER RIGHT: A water right that is made void either at the request of the water right holder or due to forfeiture.

CAP: A layer of material, such as clay or a synthetic material, used to prevent rainwater from penetrating and spreading contaminated materials. The surface of the cap is generally mounded or sloped so water will drain off.

CAPILLARITY: The property of tubes or earthlike particles with hairlike openings which, when immersed in a fluid, raise (or depress) the fluid in the tubes above (or below) the surface. of the fluid in which they are immersed.

CAPILLARY FRINGE: A area in the ground into which capillary water has moved.

CAPILLARY PHENOMENA: A phenomenon of water movement caused by capillarity.

CAPILLARY WATER: A continuous film of water found around soil particles.

CAPILLARY ZONE: The area extending from the water table to the limit of the capillary rise of the water.

CARBON DIOXIDE [CO2]: A colorless, odorless incombustible gas that is considered to be a major contributor to global warming. It is a by-product of all combustion processes.

CARBON MONOXIDE [CO] - A colorless, odorless gas resulting from incomplete combustion. Gas stoves, fireplaces, kerosene appliances, tobacco smoke, and automobile exhaust are potential sources. Proper ventilation is important to prevent negative health effects such as fatigue, dizziness and nausea.

CARBON ABSORPTION: A treatment system in which contaminants are removed from ground water and surface water by forcing water through tanks containing activated carbon, a specially treated material that attracts and holds or retains contaminants.

CAVERN: 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.

CELL: This word has more than one definition. It can be a container of chemicals used to make electricity flow in a circuit; and it is also the basic building block of all living matter. The cell of a living thing contains a high percentage of water. In solid waste disposal, one of a series of holes in a landfill where waste is dumped, compacted, and covered with layers of dirt.

CELLULOSE: The fibrous part of plants used in making paper and textiles, which in turn may be made into building products.

CELLULOSE INSULATION WITH BORATES: Cellulose insulation made from recycled newspaper treated with borates to provide fire and vermin protection. Most cellulose insulation available now uses chemical fire retardants as opposed to natural borates. (Environmentally-sensitive persons are commonly warned to avoid cellulose insulation. The ink in the newspaper may cause allergic reactions.)

CEMENTITIOUS: Having the properties of cement. Cement is the primary binding agent in concrete.

CEMENTITIOUS FOAM INSULATION: A magnesium oxide-based material blown with air to create an inert, effective insulation. It may be especially helpful for people with chemical sensitivities. It is not readily available in Texas at this time. It requires certified installers.

CERTIFICATE OF WATER RIGHT: An official document which serves as court evidence of a perfected water right.

CERTIFIED SUSTAINABLY MANAGED: Some certifying organizations have been established that oversee the harvesting of wood for lumber. The underlying guideline is preservation of a diverse forest that exhibits the same ecological characteristics as a healthy natural forest. There are few wood products presently being certified.

CFC/HCFC: Chlorofluorocarbon (CFC) and hydrogen chlorofluorocarbon (HCFC) are considered major contributors to the destruction of the Earth's ozone layer. HCFC is, 1/20th as potent as CFC in its ozone-destroying capacity. Any amount of additional threat to the ozone layer can be dangerous, due to the long term potency of CFCs. The current ozone damage is generally attributed to CFCs released 10 to 15 years ago. Twenty percent of ozone damage is caused by CRCs in insulation.

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 channel.

CHEMICAL FORMULA: Chemical symbols written together to show the atoms in a molecule, such as H2O (water).

CHLORINATED HYDROCARBONS: These include a class of persistent, broad-spectrum insecticides that linger in the environment and accumulate in the food chain. Among them are DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrine, mirex, hexachloride, and toxaphene. Other examples include TCE, used as industrial solvent.

CHLOROPHYLL A: A green photosynthetic coloring matter of plants found in chloroplasts and made up chiefly of a blue black ester.

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.

CIRCULATE: To move in a circle, circuit or orbit' to flow without obstruction to follow a course that returns to the starting point. Water can circulate in a variety of ways.

CITIZEN MONITORING: A program conducted by students or other volunteers involving the collection, management and dissemination of environmental information.

Cl - Chloride.

CLIMATE: The long-time weather conditions of a particular place. The overall kind of weather of an environment over a period of years; the average course or condition of the weather in a particular place over a period of years, as exhibited by temperature, wind velocity, and precipittion.

CLIMATIC CYCLE: The periodic changes climate, including 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.

CLOSURE: The process by which a landfill stops accepting wastes and is shutdown under Federal guidelines that ensure the public and the environment are protected.

CLOUDBURST: 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.

COAL SLURRY PIPELINE: A pipeline which transports pulverized coal suspended in liquid, usually water.

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.

COLLOIDS: Quantities of particles small enough to remain suspended in a fluid medium without settling to the bottom.

COMBINED SEWER: A sewage system that carries both sanitary sewage and strorewater runoff.

COMMENT PERIOD: Time provided for the public to review and comment on a proposed EPA action or rule making after it is published in the Federal Register.

COMMUNITY RELATIONS PLAN(CRP): The formal plan of action used by EPA to inform and educate the public affected by a Superfund site. This plan addresses all the avenues of communication to be used in a community, such as public open houses, fact sheets, workshops, and notices. It contains a list of interested citizens, citizens groups, local repositories, Federal, State, and local officials. The CRP is a CERCLA requirement meant to address a community's needs and concerns. A copy of the Plan is part of the file with the Administrative Record in the local repository.

COMPARATOR: An instrument with a calibrated color wheel used to determine the concentraiton of various parameters.

COMPOST SYSTEM: A compost system converts organic waste (food, plant material) into a rich fertilizer. Several commercial models are available that prevent odors and thwart animals.

COMPOST-CONNECTED DISPOSAL: A disposal that grinds food waste into a container where it is separated from the water rather than flowing into the waste water system. The contained food waste can then be composted.

COMPOSTING TOILET - Several commercial composting toilets are available that effectively compost human waste. The process requires no water and does not create a health odor problem when the toilet properly installed.

COMPOUND: A substance composed of separate elements, ingredients, or parts. Water is a compound made of hydrogen and oxygen.

COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION AND LIABILITY ACT OF 1980 (CERCLA): The federal law that provides remedies for abandoned hazardous waste sites. CERCLA is commonly known as Superfund.

CONCENTRATION: Amount of material dissolved in a solution; a common unit is mg/L (milligrams of dissolved material in a liter of solution).

CONDENSATION: The changing of a gas or vapor into a liquid. Water condenser.

CONDUILT: A natural or artificial channel through which fluids may be conveyed.

CONFINED GROUND WATER: A body of ground water covered by material so impervious as to sever the hydraulic connection with overlying ground water except at the intake. Confined water moves in pressure conduits due to the difference in head between intake and discharge areas of the confined water body.

CONFIRMED: A water quality issue or problem identified by a river authority as being a confirmed problem or a problem with supporting data.

CONNATE WATER: Water (pressure) trapped in the pore spaces of a sedimentary rock at the time it was deposited. It is usually highly mineralized.

CONSENT DECREE: A legal document, approved and issued by a judge, formalizing an agreement between EPA and the parties potentially responsible for site contamination. The decree describes cleanup actions that the potentially responsible parties are required to perform and/or the costs incurred by the government that the parties will reimburse, as well as the roles, responsibilities, and enforcement options that the government may exercise in the event of non-compliance by potentially responsible parties. If a settlement between EPA and a potentially responsible party includes cleanup actions, it must be in the form of a consent decree. A consent decree is subject to a public comment period.

CONSERVATION: To protect from loss and waste. Conservation of water may mena to save or store water for later use.

CONSUMPTIVE USE: Consumptive use of water is the quantity of water absorded by the crop and transpired or used directly in the building of plant tissue together with the water evaporated from the cropped area. It is the quantity of water transpired and evaporated from a cropped area or the normal loss of water from the soil by evaporation and plant transpiration. It is also the quantity of water discharged to the atmosphere or incorporated in the products of the process in connection with vegetative growth, food processig, or an industrial process.

CONTACT RECREATION: Recreational activities involving a significant risk of ingestion of water, including wading by children, swimming, water skiing, diving and surfing.

CONTAMINATION (WATER): Damage to the quality of water sources by sewage, industrial waste, or other matter.

COOL COMMUNITIES: The American Forestry Association (sponsors of Global Releaf) has selected Austin to participate in the Cool Community Program. This program encourages energy conservation in urban areas with trees and light-colored surfaces. Incentives may be available to participants.

COOLING WATER LOAD: The waste heat energy dissipated in the cooling water.

COOLING WATER REQUIREMENT: The amount of water needed to pass through the condensing unit. The amount depends on the type of cooling employed and water temperature.

CORRELATIVE RIGHTS: Certain rights of land owners over a common ground water basin are coequal, or correlative, so that any one owner cannot take more than his share even if the rights of others are impaired.

COUNTY BASELINE: State Department of Highways and Public Transportation County Map in a digital format depicting site-specific locations in latitude and longitude coordinates.

CREEK: 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.

CREOSOTES: Chemicals used in wood preserving operations and produced by distillation of tar, including polycyclic aromatic hydrocarbons and polynuclear aromatic hydrocarbons (see PAHs and PNAs). contaminating sediments, soils, and surface water, creosotes may cause skin ulcerations and cancer with prolonged exposure.

CREST: The crest is the top of a dam, dike, or spillway, which water must reach before passing over the structure. It is also the summit or highest point of a wave. The highest elevation reached by flood waters flowing in a channel is also called the crest.

CRITERIA: Water quality conditions which are to be met in order to support and protect desired uses.

CRITICAL GROUND WATER AREA: An area that has certain ground water problems, such as declining water levels. These areas are usually limited in their development and use.

CRITICAL LOW-FLOW: Low flow conditions below which some standards do not apply. The impacts of permitted discharges are analyzed at critical low-flow.

CUBIC FOOT PER SECOND (c.f.s.): A unit expressing the rate of discharge of water. One cubic foot per second is equal to the discharge through a rectangular cross section, one foot wide and one foot long, flowing at an average velocity of one foot per second. One cubic foot per second equals 448.8 gallons per minute, and 1.98 acre-feet per day. It is a rate of water movement in volume per time unit.

CURRENT: 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.

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DAM: A structure of earth, rock or concrete designed to form a basin and hold water back to make a pond, lake, or reservoir.

DAYLIGHTING STRATEGIES : These are methods that use natural light to full advantage to minimize the need for artificial lighting during the day. For example: a clerestory is a daylighting strategy that allows natural light into a building interior through a raised section of roof with vertical glass. Shading of the glass allows light in while minimizing heat gain. Louvers on the exterior of vertical glass on a house can reflect natural light into the interior without the excessive heat gain associated with harsh, direct sunlight. Horizontal light shelves, locataed high on a wall with glass above (and possibly below) and projecting into the interior and typically to the exterior as well, are excellent devices for bouncing daylight deep into a room.

DECIDUOUS: Trees and plants that shed their leaves at the end of the growing season.

DEIONIZED WATER : Ions are removed from the water so as to not interfere with chemical reacions; also called DI water.

DELTA: An alluvial deposit made of rock particles (sediment, and debris) dropped by a stream as it enters a body of water.

DEPOSIT: Something dropped or left behind by moving water, as sand or mud.

DESALINIZATION: The process of salt removal from sea or brackish water.

DESIGNATED LOCAL GOVERNMENT : A local government that has been designated through cooperative agreement or contract with the commission to perform a regional assessment pursuant to Chapter 320.1 - 320.9.

DEUTERIUM: A form of hydrogen atom in which the nucleus contains one proton and one neutron. About .0150/0 of all hydrogen atoms have such nuclei. Deuterium, also called heavy hydrogen, is the hydrogen in heavy water.

DEW POINT: The temperature at which a gas or vapor condenses to form a liquid.

DEW: The droplets of water condensed from adjacent air when the temperature falls.

DEWWATER: To remove water from wastes, soils, or chemicals.

DILLO DIRT : This is the name of the composted, sludge produced from Austin's wastewater and yard waste. It is a rich fertilizer marketed for use in landscapes - not vegetable gardens.

DILUTION: Process of adding a known amount of a solvent (usually water) to another solution to make it less concentrated. This is often done when working with fecal coliform samples to ensure proper and readable colony development.

DISCHARGE OF GROUND WATER: Occurs when water flows out from underground.

DISCHARGE PERMIT: A permit issued by the state to discharge effluent into waters of the state.

DISCHARGE: In the simplest form, discharge means outflow of water. The use of this term is not restricted as to course or location and it can be applied to describe the flow of water from a pipe or from a drainage basin. If the discharge occurs in a course or channel, it is correct to speak of the discharge of a canal or of a river. It is also correct to speak of the discharge of a canal or stream into a lake, stream or ocean. Discharge is a comprehensive outflow term. Other words related to it are runoff, stream flow and yield.

DISHWASHER : The proper use of automatic dishwashers can save water compared to hand washing (up to 37%) and may also use less energy, depending on your style of hand washing.

DISSOLVE: A condition where solid particles mix, molecule by molecule with a liquid, and appear to become part of the liquid.

DISSOLVED OXYGEN (DO): The amount of oxygen dissolved in water or sewage. Concentrations of less than 5 parts per million can limit aquatic life or cause offensive odors. Low DO is generally due to excessive organic matter present in water as a result of inadequate waste treatment and runoff from agricultural or urban land.

DISSOLVED SOLIDS: The total amount of dissolved inorganic material contained in water or wastes. Excessive dissolved solids make water unsuitable for drinking or industrial uses.

DISTILLATION: The separation of different substances in a solution by boiling off those of low boiling point first. For example, water can be distilled and the steam condensed back into a liquid that is almost pure water. The impurities (minerals) remain in the concentrated residue.

DISTRIBUTION OF WATER: The management of water which allows water users to receive the amount of water to which they are entitled by law and as supply permits.

DIVERSION: In the most simple term it means to remove water from a water body. It can also mean individually designed diversions across a hillside. They may be used to protect bottomland from hillside runoff, divert water away from active gullies, or protect buildings from runoff.

DO : Dissolved Oxygen.

DOMESTIC CONSUMPTION (USE): Water used for household purposes such as washing, food preparation and showers. It is the quantity, or quantity per capita, of water consumed in a municipality or district for domestic uses or purposes during a given period. It sometimes encompasses all uses, including the quantity wasted, lost, or otherwise unaccounted for.

DOMESTIC- HARDWOOD : deciduous trees that grow in the United States. This is the only type of wood in the U.S. where on a general scale the regeneration(production of new tries) easily exceeds the removal rate.

DRAINAGE BASIN: An area in which water drains in to a stream system.

DRAINAGE DENSITY: The number of watercourses per unit of land area.

DRAINAGE WATER: The water which has been collected by a drainage system. It may come from surface water or from water passing through the soil. It may be of a quality suitable for reuse or it may be of no further economic use.

DRAINS: Systems to control water tables near the ground surface to maintain levels at or below specified depths.

DRAWDOWN: The lowering of the water level caused by pumping. It is measured in feet for a given quantity of water pumped during a specified period, or after the pumping level has become constant.

DRILLING MUD: A mixture of clay and water that is forced through a rotating bit when drilling a well in consolidated and unconsolidated strata. The same term is used when drilling in bedrock.

DRINKING WATER STANDARDS: Drinking water standards established by state agencies, U.S. Public Health Service, and Environmental Protection Agency for drinking water in the U.S.A.

DRIP IRRIGATION: Above ground, low-pressure watering system with flexible tubing that releases small, steady amounts of water through emitters placed near individual plants.

DROP SPILLWAY: An overfall structure in which water drops over a vertical wall onto a protected apron at a lower elevation.

DROUGHT: There is no universally accepted quantitative definition of drought. Generally, the term is applied to periods of less than average precipitation over a certain period of time; nature's failure to fulfill the water wants and needs of man.

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EARTH SHELTERED DESIGN : Design of houses that are partially or totally below ground, either as a result of digging into existing topography or filling over parts of the structure. Earth sheltered design uses the constant temperature of the soil to improve energy efficiency, and can' beneficial for use of hilly sites by decreasing maintenance and environmental impact.

EARTH'S THERMAL ENERGY : A short distance below the surface, the Earth maintains a mostly constant temperature reasonably close to human comfort range. This can be used advantageously by certain heating and cooling systems. The higher temperatures found in the Earth are also used for producing electricity in some areas.

EFFECTIVE POROSITY: The portion of pore space in saturated permeable material where the movement of water takes place.

EFFECTIVE PRECIPITATION (RAINFALL): 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.

EFFICIENT FIXTURES AND APPLIANCES : Fixtures and appliances that use the least amount of energy and water and accomplish tasks are considered efficient.

EFFLUENTS: Something that flows out, usually a polluting gas or liquid discharge.

ELECTRODlALYSIS: A process which uses an electrical current and an arrangement of permeable membranes to separate soluble minerals from water. It is often used to desalinize salt or brackish water.

ELECTROMAGNETIC FIELDS (EMFs) : Electric and magnetic fields are common in nature and in all living things. Electric power produces fields that have a possible association with health risks. Continuing health risk evaluation is occurring, but avoiding excessive exposure to EMFs is recommended. Placing electric meters and panels on walls of least occupied areas is a simple method to minimize exposure to EMFs.

EMBODIED ENERGY : This is the energy invested in bringing a product or material into existence.

ENERGY EFFICIENT APPLIANCES : Energy Guide labels on appliances show energy efficiencies in dollar amounts and on a comparative basis. Refrigerators that are 20% or greater than federal standards are considered energy efficient by the GREEN BUILDER PROGRAM. The rankings are listed in the Blue Clue Energy-Efficient Refrigerator and Freezer Directory by Bonneville Power, which is available from ECSD. Front loading (horizontal axis) clothes washers are much more energy and water efficient than vertical axis machines(up to two-thirds better) and are considered energy efficient by the program. Appliance ratings are also published by the American Council for an Energy Efficient Economy and are available from ECSD.

ENERGY EFFICIENT GAS WATER HEATING : To select an energy efficient gas water heater for the GREEN BUILDER PROGRAM, first add up in gallons what the most demand for hot water could be in one hour. Then identify models that list a peak hour demand equal to or greater than your demand. This information is listed in the ÒGas Appliance Manufacturers Association's Consumer's Directory of Certified Efficiency Ratings for Residential Heating and Water Heating EquipmentÓ available at the appliance suppliers' locations or contact the ECSD Gas Efficiency Program. From the models that meet the peak hour demand, make a final selection (using the directory) from those models with a .60 or greater Energy Factor and 80% or greater Recovery Efficiency.

ENERGY EFFICIENT LIGHTING : Motion sensors and photo switches activate the exterior lights only when needed. Energy efficient bulbs and reflectors reduce the energy when lit in exterior and interior locations.

ENERGY STAR RATING : The City of Austin's Energy Star Program rates the energy efficiency of homes. A three star home is the highest rating for energy efficiency. The rating considers shading, R-values, colors, lighting and equipment efficiencies. Energy Star-rated homes all exceed energy code requirements.

ENERGY RECOVERY VENTILATOR (ERV) : Draws stale air from the house and transfers the heat or coolness in that air to the fresh air being pulled into the house. This can help reduce energy costs and dilute indoor pollutants.

ENERGY RECOVERY VENTILATOR(ERV) WITH HUMIDITY REGULATION : The ERV creates decreased or increased humidity as needed in the incoming air, a particularly appropriate feature for Austin's high humidity.

ENERGY: In scientific terms, the ability or capacity of doing work. Various forms of energy include kinetic, potential, thermal, nuclear, rotational, and electromagnetic. One form of energy may be changed to another, as when coal is burned to produce steam to drive a turbine which produces electric energy.

ENVIRONMENT: An organism's surroundings. Water is a major part of an organism's surroundings in many instances.

EROSION: 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.

ESTUARIES: An area where fresh water meets salt water; for example, bays, mouths of rivers, salt marshes, and lagoons.

EUTROPHICATION: The process of enrichment of waterbodies by nutrients. Eutrophication of a lake normally contributes to its slow evolution into a bog or marsh and ultimately to dry land. Eutrophication may be accelerated by human activities and thereby speed up the aging process.

EVAPORATION POND: A containment area where liquids are allowed to evaporate. In some cases a spraying mechanism is used to speed evaporation.

EVAPORATION: The process by which water becomes a vapor at a temperature below the boiling point.

EXTERIOR GRADE PLYWOOD : Exterior grade plywood uses phenol formaldehyde as an adhesive which outgasses in much smaller amounts compared to urea formaldehyde, which is used in interior grade plywood and particle board.

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FAHRENHEIT SCALE: A thermometric scale on which the freezing point of water is at 32 degrees above the 0 on the scale, and the boiling point is at 212 degrees.

Fe : Iron.

FEASIBILTIY STRUCTURE(FS): l. Analysis of the practicability of a proposal; e.g., a description and analysis of the potential cleanup alternatives for a site on the National Priorities List. The feasibility study usually recommends selection of a cost-effective alternative. It usually starts as soon as the remedial investigation is underway; together, they are commonly referred to as the RI/FS 2. In research, a small-scale investigation of a problem to ascertain whether or not a proposed research approach is likely to provide useful data.

FECAL COLIFORM: That portion of the coliform bacteria group which is present in the intestinal tracts and feces of warm-blooded animals.

FIELD CAPACITY: The capacity of soil to hold water. It is measured by the soil scientist as the ratio of the weight of water retained by the soil to the weight of the dry soil.

FILTER: A device used to remove solids from a mixture or to separate materials. Materials are frequently separated from water using filters.

FILTRATION: The mechanical process which removes particulate matter by separating water from solid material, usually by passing it through sand.

FIXED GROUND WATER: Water held in saturated material with pore spaces so small that it is permanently attached to the pre-walls, or moves so slowly that it is usually not available as a source of water for pumping.

FLOOD PLAIN: A strip of relatively level land bordering a stream or river. It is built of sediment carried by the stream and dropped when the water has flooded the area. It is called a water flood plain if it is overflowed in times of highwater, or a fossil flood plain if it is beyond the reach of the highest flood.

FLOOD: A flood is 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.

FLOODWAY: A part of the flood plain. The channel of a river or stream; the parts of the flood plains adjoining the channel which are reasonably required to carry and discharge the flood water or floodflow of any river or stream.

FLOW: The rate of water discharged from a source given in volume with respect to time.

FLOWING WELLS: A well where the piezometric surface lies above the ground surface.

"FlRST IN TIME, FIRST IN RIGHT" : A phrase indicating that older water rights have priority over more recent rights if there is not enough water to satisfy all rights.

FLYASH: The ash residue from high temperature combustion processes. Electric power plants using western coal, such as Austin's Fayette plant, produce a non-toxic flyash that can be a substitute for cement. Municipal waster incinerators can produce a toxic flyash which is not recommended as a component of any building material.

FOG: A cloud of condensed water vapor near the ground.

FORBAY: The water behind a dam.

FORFEITED WATER RIGHT: A water right canceled because of several consecutive years of nonuse.

FORMALDEHYDE: A colorless, pungent smelling material used as an adhering component of glues in many wood products. It can cause respiratory problems, cancer and chemical sensitivity.

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.

FREEZING: The change of a liquid into a solid as temperature decreases. For water, the freezing point is 32 F or 0 C.

FRESH:SALT WATER INTERFACE: The region where fresh water and salt water meet.

FROST: A covering of minute ice crystals on a cold surface. The temperature that causes freezing (32 degrees or below).

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GAGING STATION: The site on a stream, lake or canal where hydrologic data is collected.

GALLON: A unit of volume. A U.S. gallon contains 231 cu. in., 0.133 cubic feet, or 3.785 liters. One U.S. gallon of water weighs 8.3 lbs.

GAS: A state of matter; a substance that generally exists in the gaseous phase at room temperature.

GENERATOR: A machine that changes water power, steam power, or other kinds of mechanical energy into electricity.

GEOGRAPHIC INFORMATION SYSTEM : A map based database. Plots locations of information on maps using latitude and longitude.

GEOHYDROLOGY: 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 erosioncaused by geological processes acting over long geologic periods and resulting in the wearing away of mountains, the building up of flood plains, coastal plains, etc.

GEOLOGY: The science dealing with the general study of the earth.

GEOPRESSURED RESERVOIR: A geothermal reservoir consisting of porous sands containing water or brine at high temperature or pressure.

GEOTHERMAL ENERGY: The heat energy available in the earth's subsurface, extracted from three basic sources; (1) steam; (2) hot water; and (3) hot rocks or near surface intrusions of volcanic molten rock. The normal thermal gradient of the earth's crust is such that the temperature in a deep well or mine increased by about 1 ¡F for each 100 feet of depth.

GEYSER: A periodic thermal spring that results from the expansive force of super heated steam.

GLACIER: A huge mass of land ice that consists of recrystallized snow and moves slowly downslope or outward.

GLOBAL POSITIONING SYSTEM : A system which verifies latitude and longitude of a location on the ground through the use of a transmitter and a remote (satellite) vehicle.

GRASSED WATERWAY: A natural or constructed waterway, usually broad and shallow and covered with erosion-resistant grasses, used to conduct surface water from cropland.

GRAYWATER: Water that has been used for showering, clothes washing, and faucet uses. Kitchen sink and toilet water is excluded. This water has excellent potential to be reused as irrigation for yards.

GROUND WATER HYDROLOGY: The branch of hydrology that deals with ground water; its occurrence and movements, its replenishment and depletion, the properties of rocks that control ground water movement and storage, and the methods of investigation and utilization of ground water.

GROUND WATER LAW: The common law doctrine of riparian rights and the doctrine of prior appropriation as applied to ground water.

GROUND WATER RECHARGE: The inflow to a ground water reservoir.

GROUND WATER REGISTRATION: A statement made by a well owner registering the beneficial use of ground water.

GROUND WATER RESERVOIR: An aquifer or aquifer system in which ground water is stored. The water may be placed in the aquifer by artificial or natural means.

GROUND WATER RUNOFF: A 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.

GROUND WATER STORAGE: The storage of water in ground water reservoirs.

GROUND WATER: The supply of fresh water found beneath the Earth's surface (usually in aquifers) which is often used for supplying wells and springs. Because ground water is a major source of drinking water, there is growing concern over areas where leaching agricultural or industrial pollutants or substances from leaking underground storage tanks are contaminating ground water.

GULLY EROSION: The development of relatively deep, steep-sided channels from small rills and water courses that have not been eradicated with tillage and have become too deep to permit normal farming operations.

GULLY: A deeply eroded channel caused by the concentrated flow of water.

GYPSUM/CELLULOSE: An interior wallboard product that uses cellulose from recycled newspapers with gypsum and perlite.

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HAIL: 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 it is carried up and down in highly turbulent air currents.

HARDPAN: A shallow layer of earth material which has become relatively hard and impermeable, usually through the deposition of minerals.

HARVESTED RAINWATER : The rain that falls on a roof or yard and is channeled by gutters or channels to a storage tank. the first wash of water on a roof is usually discarded and the subsequent rainfall is captured for use if the system is being used for potable water. Good quality water is available by this method in most areas.

HAZARDOUS RANKING SYSTEM (HRS): The principal screening tool used by the EPA to evaluate risks to public health and the environment associated with abandoned or uncontrolled hazardous waste sites. The HRS calculates a score based on a formula which is the primary factor in deciding if the site should be on the National Priorities List, and if so, what ranking it should have in comparison to other sites on the list.

HAZARDOUS WASTE: By-products of society that can pose a substantial or potential hazard to human health or the environment when improperly managed. Possesses at least one of four characteristics (ignitability, corrosivity, reactivity, or toxicity), or appears on special EPA lists.

HEADGATE: 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.

HEALTH ASSESSMENT: An evaluation of data and information gathered on the release of hazardous substances into the environment to assess any current or future impact on public health.

HEALTHY HOME: A "healthy home" is built with least-toxic building materials and is designed to support and contribute to a better indoor environment.

HEAVY WATER MODERATED REACTOR: A reactor that uses heavy water as its moderator. Heavy water is an excellent moderator and thus permits the use of inexpensive (unenriched) uranium as a fuel.

HEAVY WATER: Water composed of isotopes of hydrogen of atomic weight greater than 1 or of oxygen greater than 16, or both; especially water composed of ordinary oxygen and the isotope of hydrogen of atomic weight 2; deuterium oxide (D2O).

HEAVY METALS: Metallic elements with high atomic weights, e.g., mercury, chromium, cadmium, arsenic, and lead. They can damage living things at low concentrations and tend to accumulate in the food chain.

HIGH QUALITY DUCT SYSTEM : this method of designing and installing ductwork avoids potentially significant heating and cooling losses and potential health hazards caused by depressurizing or pressurizing a house. Manuals J and D calculations are used to engineer the system. All ducts are sealed using a fibrated latex mastic and fiberglass tape, or metal tape meeting SMACNA standard 181. Both inner and outer linings of the duct are sealed. The air handler, support platform, and return plenum are sealed air tight at all joints. Duct tape is not used in any part of the system. The system can be performance tested to ensure proper installation.

"HIGHEST AND BEST USE": The classification of water based on an analysis of the greatest needs of the future. Certain quantities are reserved for appropriation according to the classification.

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.

HORIZONTAL AXIS CLOTHESWASHER : See Energy Efficient Appliance.

HOT ROCK RESERVOIR: A potential source of geothermal power. The Òhot rockÓ system requires drilling deep enough to reach heated rock, then fracturing it to create a reservoir into which water can be pumped. This technique has not yet been perfected.

HUMID: Containing or characterized by perceptible moisture. Usually refers to the atmosphere.

HUMIDITY: The condition of the atmosphere in respect to its content of water vapor.

HYDRAULIC RAM: A device which uses the energy of falling water to force a small portion of the water to a height greater than the source.

HYDRO: The prefix denoting water or hydrogen.

HYDROCARBONS: Chemical compounds that consist entirely of carbon and hydrogen such as petroleum, natural gas, and coal.

HYDROELECTRIC PLANT, CONVENTIONAL: A hydroelectric power plant which utilizes stream flow only once as the water passes downstream, as opposed to a pumped storage plant which recirculates all or a portion of the stream flow in the production of power.

HYDROELECTRIC: Having to do with production of electricity by water power from falling water.

HYDROELECTRICITY: Electric energy production by water powered turbine generators.

HYDROGEN: A chemical substance found in most fuels; by itself, a colorless gas that burns quickly. It is a major component of water.

HYDROGEOLOGY: The science dealing with the occurrence, distribution, and movement of water below the surface of the earth, with a greater emphasis on geology.

HYDROGRAPH: A graphic plot of changes in the flow of water or in the elevation of water level plotted against time.

HYDROLOGIC CYCLE (WATER CYCLE): The cycle of water movement from the atmosphere to the earth and back to the atmosphere through various processes. These processes include: precipitation, infiltration, percolation, storage, evaporation, transpiration and condensation.

HYDROLOGY: The science dealing with the properties, distribution and circulation of water.

HYDROMETER: An instrument used to measure the density of a liquid.

HYDROPOWER: Power produce by falling water.

HYDROSEEDING: Dissemination of seed under pressure, in a water medium. Mulch, lime, and fertilizer can be incorporated in the spraying mixture.

HYDROTHERMAL RESERVOIR: One of three forms of geothermal reservoir systems. It consists of naturally circulating hot water or steam (Òwet steamÓ) or that which contains mostly vapor (Ò`dry steamÓ). The latter type of reservoir is the most desirable type according to present technology.

HYGROMETER: An instrument used to measure humidity.

HYGROSCOPIC WATER: Water which is absorbed from the air.

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ICE: A solid form of water.

ICEBERG: A large piece of ice that breaks off and floats away from a glacier.

IMPERVIOUS: A term denoting the resistance to penetration by water or plant roots.

IMPORT: Water piped or channeled into an area.

IMPOUNDMENT: 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.

IMPOUNDMENT: A body of water or sludge confined by a dam, dike, floodgate, or other barrier.

IN-SITU BIODEGRADATION: Treatment of soil in place to encourage contaminants to breakdown. It involves aerating the soil and adding nutrients to promote growth of microorganisms.

IN-SITU VITRIFICATION: A technology used to treat hazardous waste in soils. This process electrically melts the waste media at extremely high temperatures then allows it to cool, creating an extremely stable, insoluble, glasslike solid. The contaminants are destroyed or immobilized and the total volume of material is reduced.

INCHOATE WATER RIGHT: An unperfected water right.

INDIGENOUS STONE: Stone from the Austin region such as limestone and granite.

INFILTRATION: The gradual downward flow of water from the surface into soil material.

INFLUENT SEEPAGE: The movement of gravity water in the zone of aeration from the ground surface toward the water table.

INORGANIC CHEMICALS/COMPOUNDS: Chemical substances of mineral origin, not of basically carbon structure. These include metals such as lead and cadmium.

INTENSIVE SURVEY: An analysis of loadings to a stream segment.

INTERMITTENT STREAM : A stream which has a period of zero flow for at least one week during most years. Where flow records are available, a stream witha7Q2 flow of less than 0.1 cubic feet per second is considered intermittent.

INTERSTATE WATER: According to law, 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.

INTERSTlCES: The void 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: The applied irrigation , 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 restricted to measurable water returning to the stream from which it was diverted.

IRRIGATION WATER: Water which is applied to assist crops in areas where rainfall is inadequate.

IRRIGATION: The controlled application of water for cultural purposes through man-made systems to supply water requirements not satisfied by rainfall.

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JETTY: A structure extended into a sea, lake, or river to influence the current or tide or to protect a harbor.

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KILOWATT-HOUR(KWH) : A measure of electric usage equivalent to the use of 1,000 watts for one hour.

KITCHEN RECYCLING CENTER: A built-in section of the kitchen cabinetry that allows convenient separation of recyclable materials.

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LAG TIME: The time from the center of a unit storm to the peak discharge or center of volume of the corresponding unit hydrograph.

LAGOON: A shallow pond where sunlight, bacterial action, and oxygen work to purify waste water. Lagoons are typically used for the storage of waste waters, sludges, liquid wastes, or spent nuclear fuel.

LAKES: An inland body of water, usually fresh water, formed by glaciers, river drainage etc., larger than a pool or pond. Bodies of water filling depressions in the earth's surface.

LANDFARM: To apply waste to land and/or incorporate waste into the surface soil, such as fertilizer or soil conditioner. This practice is commonly used for disposal of composted wastes.

LANDFILL: A disposal facility where waste is placed in or on land.

LEACHING: The process by which soluble materials in the soil, such as nutrients, pesticide chemicals or contaminants, are washed into a lower layer of soil or are dissolved and carried away by water.

LEAD : A harmful environmental pollutant that is typical in older homes with lead-based paints and in the lead solder used in plumbing. Lead is toxic to many organs and can damage the brain, kidneys, and nervous system.

LEAKING PETROLEUM STORAGE TANK : Those storage tanks which have been assigned a leaking petroleum storage tank (LPST) number by the Texas Water Commission.

LEAST-TOXIC: This characterization of a building material for the Green Builder Program indicates that urea formaldehyde is not present and/or VOC contents are minimal and/or water-based constituents are used. Products that have been certified to be "least-toxic" by certification groups such as Creen Cross, Green Shield, and Eco-Logo qualify for the Green Builder Program.

LEVEE: 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.

LIFE CYCLE: A life cycle assessment (LCA) is an objective process to evaluate all the environmental burdens of a product or process through its entire existence. This encompasses extracting and processing raw materials, manufacturing, transportation, distribution, use and maintenance, recycling and final disposal.

LIGHT WATER REACTOR (LWR): A power plant which uses ordinary water as distinguished from one that uses heavy water. Fission energy is released in the form of heat and is transferred to a conventional steam cycle which generates electric energy.

LIMESTONE: A sedimentary rock composed of calcium carbonate (lime) and sometimes containing shells and other hard parts of prehistoric water animals and plants.

LIQUID: A state of matter, neither gas nor solid, that flows and takes the shape of its container.

LlMNOLOGY: That branch of hydrology pertaining to the study of lakes.

LONG-TERM REMEDIAL PHASE: Distinct, often incremental, steps that are taken to solve site pollution problems. Depending on the complexity, site cleanup activities can be separated into a number of these phases.

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MAGMATlC WATER: Water driven out of magma during crystallization.

MATTER: Anything which is solid, liquid or gas, and has mass.

MEDIAN STREAM FLOW (MEDIAN HYDRO): The rate of discharge of a stream for which there are equal numbers of greater and lesser flow occurrences during a specified period.

MELTING: The changing of a solid into a liquid.

MELTWATER: Water that comes from the melting ice of a glacier or a snowbank.

MEMORANDUM OF UNDERSTANDING (MOO): An interagency agreement defining which agency has a responsibility.

METEORIC WATER: New water derived from the atmosphere.

METEOROLOGY: The science of the atmosphere; the study of atmospheric phenomena.

METHANE (CH4) : An odorless, colorless, flammable gas that is a major constituent of natural gas. It is a more powerful global warming agent than carbon dioxide.


mg/L : Milligrams per liter.

MIGRATION: The movement of oil, gas, contaminants, water, or other liquids through porous and permeable rock.

MINERAL: Any naturally occurring inorganic element or chemical compound. Rocks are a compound of minerals.

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.

MITIGATION: When used in the context of environmental assessments, it refers to an action designed to lessen or reduce adverse impacts.

Mn : Manganese.

MOISTURE: Water diffused in the atmosphere or the ground.

MOLECULE: A very small bit of matter. The smallest amount of a compound which has all the properties of the compound.

MUNICIPAL SEWAGE: Sewage from a community which may be composed of domestic sewage, industrial wastes or both.

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N : Nitrogen.

NATIONAL PRIORITIES LIST (NPL): EPA's list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under Superfund. A site must be on the NPL to receive money from the Trust Fund (Superfund) for remedial action. The list is based primarily on the score a site receives from the Hazard Ranking System. EPA is required to update the NPL at least once a year.

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 country.

NATURAL LINOLEUM: Cork is the primary material in natural linoleum. cork is from the bark of the cork tree and is harvested without destroying the trees.

NIMBUS CLOUDS: Storm clouds that are usually dark in color.

NITROGEN: A nutrient present in ammonia, nitrate or nitrite or elemental form in water due possibly to nonpoint source pollution or improperly operating wastewater treatment plants.

NITROGEN OXIDE(N0) : A colorless, poisonous gas. It is a by-product of gas combustion.

NlMBOSTRATUS CLOUDS: Rain clouds in layers that are generally spread across the sky.

NON-CONSUMPTIVE USE: Using water in a way that does not reduce the supply. Examples include hunting, fishing, boating, water-skiing, swimming, and some power production.

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.

NONPOINT SOURCE (NPS) POLLUTION: Forms of 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 occurs when the rate of materials entering these waterbodies exceeds natural levels.

NONPOROUS: Something which does not allow water to pass through it.

NUCLEAR WASTE: The radioactivity by-products and contaminated materials produced in nuclear powered electric generating facilities. There is no proven method for safely disposing of these wastes, some of which can be toxic for thousands of years.

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OCEAN THERMAL GRADIENTS: The temperature difference between deep and surface water in the oceans.

OCEANOGRAPHY: The science relating to the study of the ocean.

OCEANS: The great bodies of salt water which cover more than two-thirds of the earth's surface.

OLD-GROWTH: Wood from trees found in mature forests. In many cases, the trees have never been exposed to logging operations. In the Northwest U.S., only about 10% of these biologically rich areas are left. It is difficult to know which wood is from old-growth areas when buying wood locally.

OPERABLE UNIT: Term for each of a number of separate activities undertaken as part of a Superfund site cleanup. A typical operable unit would be the removal of drums and tanks from the surface of a site.

OPERATION AND MAINTENANCE: 1. Activities conducted at a site after a Superfund site action is completed to ensure that the action is effective and operating properly. 2. Actions taken after construction to assure that facilities constructed to treat waste water will be properly operated, maintained, and managed to achieve efficiency levels and prescribed effluent limitations in an optimum manner.

ORGANIC CHEMICALS/COMPOUNDS: Animal or plant- produced substances containing mainly carbon, hydrogen, and oxygen, such as benzene and toluene.

ORGANIC WASTE: Natural materials, such as food and yard waste, that decompose naturally.

ORGANISM: Any living thing; either plant or animal.

ORIFlCE: As used in water studies: An opening with a closed perimeter; is usually sharp edged, and of regular form in a plate, wall, or partition through which water may flow. An orifice is used for the measurement or control of water.

OUTFALL : A designated outfall pursuant to a commission issued discharge permit or NPDES permit.

OUTGAS: The emitting of fumes into the air.

OUTWASH: A deposit of sand and gravel formed by streams of meltwater flowing from a glacier.

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P : Phosphorous. A nutrient.

PARTICULATE MATTER: Solid material that escapes from combustion processes (fires).

PARTS PER MILLION (PPM): The number of parts by weight of a substance per million parts of water. This unit is commonly used to represent pollutant concentrations. Large concentrations are expressed in percentages.

PASSIVE COOLING: The building's structure is designed to permit increased ventilation and retention of coolness within the building components. The intention is to minimize or eliminate the need for mechanical means of cooling.

PASSIVE DESIGN: Building design and placement that allows the use of natural processes such as radiation, convection, absorption, and conduction to minimize energy costs.

PASSIVE HEATING: The building's structure is designed to allow natural thermal energy flows such as radiation, conduction, and natural convection generated by the sun to provide heat.

PASSIVE SOLAR WATER HEATER: A water heating system that does not require mechanical pumps or controls to create hot water for domestic use. there are several types available commercially.

PAY-AS-YOU-THROW : A City of Austin garbage service that charges the user according to the amount of garbage generated.

Pb : Lead. A heavy metal.

PCB : Polychlorinated Biphenyls. A toxic material.

PENSTOCK: A gate or sluice used in controlling the flow of water. A tube or trough for carrying water to a water wheel, or a pipe carrying water to an electric turbine.

PERCOLATING WATERS: Waters which pass through the ground beneath the earth's surface without a definite channel. It is presumed that ground waters percolate.

PERCOLATION: The movement of water through the subsurface soil layers, usually continuing downward to the ground water or water table reservoirs.

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.

PERFORATION OF WELLS: Holes in the casing of wells which allow water to flow into the well.

PERLITE: A natural volcanic glass that expands with heat and transforms into a fluffy form that can be used for insulation purposes.

PERMAFROST: The part of the earth's surface that is permanently frozen.

PERMEABILITY: 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 gradient.

PERMIT: Any right or authorization granted by the Texas Water Commission or its predecessor agencies, including wastewater disposal permits, water rights permits, certificates of adjudication and certified filings.

PERSPIRE: To produce sweat or salty water from glands in the skin. A natural way of cooling the body by the evaporation of water.

PERVIOUS PAVING : Paving material that allows water to penetrate to the soil below.

PETROCHEMICALS: Chemical substances produced from petroleum in refinery operations and as fuel oil residues. These include fluoranthene, chrysene, mineral spirits, and refined oils. Petrochemicals are the bases from which volatile organic compounds (VOCs), plastics, and many pesticides are made. These chemical substances are often toxic to humans and the environment.

pH: A way of expressing both acidity and alkalinity on a scale of 0:14, with 7 representing neutrality; numbers less than 7 indicate increasing acidity and numbers greater than 7 indicate increasing alkalinity.

PHOTOSYNTHESIS: A process in green plants in which water, carbon dioxide, and sunlight combine to form sugar.

PHOTOVOLTAIC: the process of converting sunlight directly into electricity. The electricity can be used immediately, stored in batteries, or sold to a utility. Costs continue to drop and efficiency is improving for this technology. Austin has favorable sun conditions for using photovoltaics.

PHREATOPHYTES: Plants that send their roots into or below the capillary fringe to use ground water.

PHYSICAL-CHEMICAL TREATMENT PROCESSES: A means of wastewater treatment using both physical and chemical processes.

PLACE OF USE: The specific location where water is applied or used. A water user cannot use water at another location without transferring the right or obtaining a new right.

PLAYAS: The flat:floored bottom of an undrained desert basin which may become a shallow lake.

PlEZOMETRIC SURFACE: An imaginary surface which coincides with the hydrostatic pressure level of the water in an aquifer.

PLUME: A visible or measurable discharge of a contaminant from a given point of origin. It can be visible or thermal in water or visible in the air, such as a plume of smoke.

PO4 : Phosphate. A nutrient.

POINT OF DIVERSION: The point from which water is diverted from a source.

POINT SOURCE POLLUT!ON: This type of water pollution results from the discharges into receiving waters from easily identifiable ÒpointsÓ. Common point sources of pollution are discharges from factories and municipal sewage treatment plants.

POINT SOURCE: A stationary source of a large individual air pollution emission, generally of an industrial nature. This is a general definition, as point source is legally and precisely defined in federal regulations.

POLLUTED: Something which contains foreign substances.

POLLUTION: The alteration of the physical, thermal, chemical or biological quality of, or the contamination of, any water in the state that renders the water harmful, detrimental, or injurious to humans, animal life, vegetation, or property or to public health, safety, or welfare, or impairs the usefulness or the public enjoyment of the water for any lawful or reasonable purpose.

POLYCHLORINATED BIPHENYLS (PCBs): A group of toxic chemicals used for a variety of purposes including electrical applications, carbonless copy paper, adhesives, hydraulic fluids, microscope emersion oils, and caulking compounds. PCBs are also produced in certain combustion processes. PCBs are extremely persistent in the environment because they are very stable, non- reactive, and highly heat resistant. Chronic exposure to PCBs is believed to cause liver damage. It is also known to bioaccumulate in fatty tissues. PCB use and sale was banned in 1979 with the passage of the Toxic Substances Control Act.

POLYCYCLIC AROMATIC HYDROCARBONS or POLARAROMATIC HYDROCARCONS (PAHs): PAHs, such as pyrene, are groups of highly reactive organic compounds. They are a component of creosotes and can cause cancer.

POLYNUCLEAR AROMATIC HYDROCARBONS(PNAs): PNAs, such as naphthalene, and biphenyls, are a group of highly reactive organic compounds that are a common component of creosotes, which can be carcinogenic.

PORE SPACE: That portion of rock or soil not occupied by solid mineral matter and which may be occupied by ground water.

POROSITY: That part of a rock which contains pore spaces without regard to size, shape, interconnection, or arrangement of openings. It is expressed as percentage of total volume occupied by spaces.

POROUS: A condition which allows liquids to pass through.

POTABLE WATER: Drinkable water.

POTENTIAL : A water quality issue or problem identified by a river authority as being a potential problem, or a problem without current supporting data.

POTENTIALLY RESPONSIBLE PARTIES(PRPs): Parties, including owners, who may have contributed to the contamination at a Superfund site and may be liable for costs of response actions. Parties are considered PRPs until they admit liability or a court makes a determination of liability. This means that PRPs may sign a consent decree or administrative order on consent to participate in site cleanup activity without admitting liability.

POTHOLE: A hole eroded in the solid rock of a stream bed by water carried sand and pebbles.

POWDER PILLOW: Small, plastic containers with premeasured amounts of chemicals; easily opened with nail clippers.

PRECIPITATE(floc) : Material which is insoluble in water and will settle out over time.

PRECIPITATION GAGE: A device used to collect precipitation and measure precipitation.

PRECIPITATION: A deposit on the earth of hail, rain, mist, sleet, or snow. It is the common process by which atmospheric water becomes surface or subsurface water. The term ÒprecipitationÓ is also commonly used to designate the quantity of water precipitated.

PRESSURE-TREATED WOOD: Wood that is chemically preserved to prevent moisture decay. The process uses environmentally dangerous chemicals and there can be health hazards form working with, or coming into contact with, the material. If pressure:treated wood is required for a residential application, CCA preserved wood is the better choice at this time. Follow all safety procedures when using this type of material.

PRESSURIZED WATER REACTOR: A reactor in which water, heated by nuclear energy, is kept at high pressure to prevent the water from boiling. Steam is then generated in a secondary coolant loop.

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.

PROGRAMMABLE THERMOSTAT : A mechanical or electronic device that regulates the temperature setting and time of day operation of heating and cooling systems. the temperature and time of day settings are determined by the user so that optimal efficiency can be attained while maintaining comfort levels as needed.

PROPER VENTILATION: Combustion gases are vented completely to the outdoors. Combustion gases that escape into a living space can pose health hazards such as lung cancer. Radon concentrations are rare in Austin.

PUDDLE: A small pool of water, usually a few inches in depth and from several inches to several feet in its greatest dimension.

PUMP: 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.

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RADIANT BARRIER: A layer of metallic foil that reflects thermal radiation without transferring heat to other materials.

RADON: A radioactive, colorless, odorless gas that occurs naturally in the earth. When trapped in buildings, concentrations build up, and it can cause health hazards such as lung cancer.

RAIN GAGE: Any instrument used for recording and measuring time, distribution, and the amount of rainfall.

RAIN SENSOR: A simple, inexpensive device that measures rainfall and prevents unnecessary irrigation with an automatic controller.

RAIN: Water drops which fall to the earth from the air.

RAINFALL: The quantity of water that falls as rain only.

RAMMED EARTH: A building technique for exterior walls where earth is "rammed" (or processed down) between forms. Certain mixtures of moistened earth used in this technique harden under pressure and form a strong solid wall which is then covered by a waterproofing coat.

REAGENT: Chemical added to a sample; may be in powder or liquid form.

RECHARGE, ARTIFICIAL: The infusion of surface water into wells; seepage of water into soil or gravelly areas for storage.

RECHARGE: The addition of water into a ground water system.

RECLAMATION: The process of matter or energy being reclaimed or restored to a better or useful state. For instance, dams reclaim water which would otherwise be lost through runoff.

RECONSTITUED: The process of taking small pieces of material and binding them together to form a larger item. Examples include wood chips that are adhered together to form substrates and/or structural components in trim, doors, windows, structural material, and sheet materials. Fingerjointed and laminated materials are other examples.

RECORD OF DECISION(ROD): A public document that explains which cleanup alternative(s) will be used at Superfund sites where Superfund pays for the cleanup. The Record of Decision is based on information and technical analyses generated during the remedial investigation/feasibility study and consideration of public comments and community concerns.

RECORDER, STREAM DATA: A mechanical apparatus which records a continuous record of a water level.

RECYCLED PLASTIC LUMBER: Recycled plastic made into lumber which is workable like lumber. There are several manufacturers of this material. It is insect and water resistant.

REFRIGERATOR: see "Energy Efficient Appliances".

RELATIVE HUMIDITY: The ratio of the amount of water vapor actually present in the air to the greatest amount possible at the same temperature.

REMEDIAL ACTION(PA): The actual construction or implementation phase of a Superfund site cleanup that follows remedial design.

REMEDIAL DESIGN(RD): An engineering phase that follows the remedial investigation/feasibility study and includes development of engineering drawings and specifications for a site cleanup.

REMEDIAL INVESTIGTION (RI): An in-depth study designed to gather the data necessary to determine the nature and extent of contamination at a Superfund site; establish criteria for cleaning up the site; identify preliminary alternatives for remedial actions; and support the technical and cost analyses of the alternatives. The remedial investigation is usually done with the[feasibility study. Together they are usually referred to as the RI/PS.

REMEDIAL PROJECT MANAGER (RPM): The EPA or state official responsible for overseeing remedial action at a site.

REMEDIAL RESPONSE: A long-term action that stops or substantially reduces a release or threatened release of hazardous substances that is serious, but does not pose an immediate threat to public health and/or the environment.

REMOVAL ACTION: Short-term immediate actions taken to address releases of hazardous substances that require expedited response.

REPOSITORY: A facility where official Superfund documents are kept for public reference. Each Superfund site has at least one repository- usually the local library or other public facility.

RESERVOIR: A pond, lake, tank, or basin (natural or human made) where water is collected and used for storage. Large bodies of ground water are called ground water reservoirs; water behind a dam is also called a reservoir of water.

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.

RISK ASSESSMENT: The qualitative and quantitative evaluation performed in an effort to define the risk posed to human health and /or the environment by the presence or potential presence and/or use of specific pollutants.

RIVER BASIN: A term used to designate the area drained by a river and its tributaries.

RIVER AND COASTAL BASIN: The river and coastal basins now degined and designated by separate units for the purposes of water development and inter-watershed transfers, and as they are made certain by contour maps on file in the offices of the Texas Water Development Board, including but not limited to the rivers and their tributaries, streams, water, coastal water, sounds, estuaries, bays, lakes and portions of them, as well as the lands drained by them.

RIVER AUTHORITY: Any district or authority created by the legislature which contains an area within its boundaries of ten or more counties and which is governed by a hoard of directors appointed or designated in whole or in part by the governor, or by the Texas Water Development Board, including without limitation the San Antonio River Authority, and other river authority or Special district created under Article111, Section 52, Subsection (b)(1) or (2), or Article XVI, Section 59, of the Texas Constitution that is designated by rule of the commission to comply with this chapter.

RIVER: A natural stream of water of considerable volume.

RlPRAP: A facing layer (protective cover) of stones placed to prevent erosion or the sloughing off of a structure or embankment.

RULE ELEMENT: A component and constituent of the regional assessment report.

RUN-OFF: Water from rainfall or irrigation that is allowed to flow off the property. Run-off can be thought of as a lost resource and a contributor to non:point source pollution.

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S04 : Sulfate.

SALINITY: The total dissolved solids in water alter all bromide and iodide have been replaced by chloride, and all organic matter has been oxidized. For most purposes, salinity is considered equivalent to total dissolved salt content. Salinity is normally expressed in parts per thousand.

SALT WATER: Water which contains a relatively high percentage of sodium chloride.

SAND BARRIER TERMITE PROTECTION: A shallow trench around the perimeter of the house foundation that is filled with sand. Termites cannot pass through the barrier because their tunnels cave in.

SAP: A type of fluid contained within a plant.

SATURATION, ZONE OF: The zone below the watertable in which all pore spaces are filled with ground water.

SCENIC WATERWAY: Rivers or river segments chosen for scenic and recreational qualities to be preserved in their natural state.

SEDIMENT: Transported and deposited particles derived from rocks, soil, or biological material.

SEDIMENT: The layer of soil, sand and minerals at the bottom of surface water, such as streams, lakes, and rivers that absorb contaminants.

SEDIMENTATION: The removal, transport, and deposition of detached soil particles by flowing water or wind.

SEEPAGE: The appearance and disappearance of water at the ground surface. Seepage designates the type of movement of water in saturated material. It is different from percolation, which is the predominant type of movement of water in unsaturated material.

SEPTIC TANKS: These are used to hold domestic wastes when a sewer line is not available to carry them to a treatment plant. The wastes are piped to underground tanks directly from a home or homes. Bacteria in the wastes decompose some of the organic matter and sludge settles on the bottom of the tank and the effluent flows out of the tank into the ground through drains.

SILTATION: The deposition of finely divided soil and rock particles upon the bottom of stream and river beds and reservoirs.

SLEET: Precipitation which is a mixture of rain and ice.

SLUDGE: Precipitated solid matter produced by water and sewage or mineral treatment processes.

SLURRY WALL: Barriers used to contain the flow of contaminated fund water or subsurface liquid. Slurry walls are constructed by digging a trench around a contaminated area and filling the trench with an impermeable material that prevents water from passing through it. The ground water or contaminated liquids trapped within the area surrounded by the slurry wall can be exacted and treated.

SNOW COURSE: A line laid out and permanently marked on a drainage area along which the snow is sampled at definite distances or stations. Sampling occurs at appropriate times to determine snow depth, water equivalent, and density.

SNOW DENSITY: Ratio between the volume of melt water derived from a sample of snow and the initial volume of the sample.

SNOW FIELD: An area, usually at high elevation or in polar latitudes, where snow accumulates and remains throughout the entire year.

SNOW SURVEY: The process or operation of determining the depth, water content, and density of snow at various selected points on a drainage basin. This is done in order to determine the amount of water stored there in the form of snow for the purpose of forecasting runoff.

SNOW: 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.

SNOWFALL: The amount of snow, hail, sleet, or other precipitation occurring in solid form which reaches the earth's surface. It may be expressed in depth in inches after it falls, or in terms of inches in depth of the equivalent amount of water.

SNOWFLAKE: Precipitation which is made up of a number of snow crystals fused together.

SNOWPACK: The winter accumulation of snow in mountain areas.

SOAKER HOSE: Low-flow watering device with small holes throughout the surface of the hose. Good for plant beds and gardens.

SOIL MOISTURE (SOIL WATER): Water diffused in the soil. It is found in the upper part of the zone of aeration from which water is discharged by transpiration from plants or by soil evaporation.

SOIL MOISTURE SENSOR: A device which can be attached to any automatic irrigation system that monitors level drops below the desired level.

SOLID WASTE: Any garbage, refuse, sludge from a waste treatment plant, water supply treatment plant or air pollution control facility, and other discarded material, including solid, liquid, semisolid, or contained gaseous materials resulting from industrial, municipal, commercial, mining, and agricultural operations, and from community and institutional activities, but does not include: (A) Solid or dissolved material in domestic sewage, or solid or dissolved material in irrigation return flows, or industrial discharges subject to regulation by permit issued pursuant to Chapter 26, Texas Water Code; (B) Soil, dirt, rock, sand, and other natural or manmade inert solid materials used to fill land if the object of the fill is to make the land suitable for the construction of surface improvements; or (C) Waste materials which result from activities associated with the exploration, development, or production of oil or gas and are subject to control by the Railroad Commission of Texas.

SOLID: A state of matter, neither liquid or gas. The solid state of water is ice.

SPECIFIC HEAT: The heat capacity of a material per unit mass. The amount of heat (in calories) required to raise the temperature of one gram of a substance 1 C; the specific heat of water is 1 calorie. SPILL: To cause or allow to run or fall from a container unintentionally so as to be lost or wasted. It is also the overflow from a reservoir after it is full.

SPlLLWAY: The channel or passageway around or over a dam through which excess water is diverted.

SPRING RUNOFF: Snow melting in the spring causes water bodies to rise. This in streams and rivers is called "spring runoff".

SPRING: A concentrated discharge of ground water coming out at the surface as flowing water.

STABILIZATION: The process' of changing an active substance into inert, harmless material, or physical activities at a site that act to limit the further spread of contamination without actual reduction of toxicity.

STANDARD : A pre-mixed solution with a known amount of material to be tested; can be used for calibration but also to check monitoring accuracy.

STEAM, DRY: A steam that is so hot that no water droplets are present in it.

STEAM: The vapor that forms when water is heated to the boiling point. Steam under pressure is capable of driving a piston in a piston engine or turning the blade of a turbine.

STERILIZATION: A cleansing process that removes possible contamination by bacteria; used with fecal coliform testing equipment.

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.

STORM: A change in the ordinary conditions of the atmosphere which may include any or all meteorological disturbances such as wind, rain, snow, hail, or thunder.

STORMWATER DRAINAGE SYSTEM: Man-made and natural features which function as a system to collect, convey, channel, hold, inhibit, retain, detain, infiltrate, or divert stormwater runoff.

STRAW BALE TECHNIQUE: A building technique for exterior walls where straw (not hay) bales are stacked, reinforced and interlocked in a manner that forms a thick, highly insulated wall. This technique was used in early structures in the Plains region of the U.S. It is currently being revived here and in Europe.

STRAW-MUD: this is an old building technique for exterior walls where earth material is mixed with straw, moistened and pressed between forms where it hardens into a strong wall. It is then covered with a waterproofing plaster system.

STREAM GAGING: A process of determining the rate of flow, or the discharge, of streams.

STREAM SEGMENT: Surface waters of an approved plannmg area exhibiting common biological, chemical, hydrological, natural, and physical characteristics and processes. Segments will normally exhibit common reactions to external stresses (e.g. discharge or pollutants). Segments are enumerated using a four digit number. The first two digits identify the basin in which the segment is located. The last two digits distinguish the segments within a particular river, coastal or estuarine basin. Boundaries of bay and estuarine segments (identified with the number 24 as the first two digits) have not been precisely defined and are illustrated as approximations at this time.

STREAM: A general term for a body of flowing water. In hydrology the term is generally applied to the water flowing in a natural channel as distinct from a canal. More generally, it is applied to the water flowing in any channel, natural or artificial. Some types of streams: 1. Ephemeral: A stream which flows only in direct response to precipitation, and whose channel is at all times above the water table. 2. Intermittent or Seasonal: A stream which flows only at certain times of the year when it receives water from springs, rainfall, or from surface sources such as melting snow. Perennial: A stream which flows continuously.3. Gaining: A stream or reach of a stream that receives water from the zone of saturation. An effluent stream. 4. Insulated: A stream or reach of a stream that neither contributes water to the zone of saturation nor receives water from it. It is separated from the zones of saturation by an impermeable bed. 5. Losing: A stream or reach of a stream that contributes water to the zone of saturation. An influent stream. 6. Perched: A perched stream is either a losing stream or an insulated stream that is separated from the underlying ground water by a zone of aeration. 6. SWAMPS: Shallow lakes where a small depth of water and a slight range of fluctuation permits the growth of aquatic vegetation.

STREAMFLOW DEPLETION: The amount of water that annually flows into a valley or onto a particular land area minus the amount that flows out of thevalley or away from the particular land area. It is also the amount of water taken from a stream.

STREAMFLOW: The discharge that occurs in a natural channel. Although the term discharge can be applied to the flow of a canal, the word streamflow uniquely describes the discharge in a surface stream course. The term Ò"streamflow" is more general than runoff, as stream flow may be applied to discharge whether or not it is affected by diversion or regulation.

SUBSURFACE WATER: All water which occurs below the ground surface.

SURFACE WATER : Lakes, bays, ponds, impounding reservoirs, springs, rivers, streams, creeks, estuaries, wetlands, marshes, inlets, canals, gulfs inside the territorial limits of the state, and all other bodies of surface water, natural or artificial, inland or coastal, fresh or salt, navigable or nonnavigable, and including the beds and banks of all watercourses and bodies of surface water, that are wholly or partially inside or bordering the state or subject to the jurisdiction of the state; except that waters in treatment systems which are authorized by state or federal law, regulation, or permit, and which are created for the purpose of waste treatment are not considered to be waters in the state.

SULPHUR DIOXIDE(SO2) : A colorless, irritating gas that is a primary cause of acid rain. It is a by-product of coal combustion.

SUPERFUND SITE: Any facilities identified in the State Registry pursuant to 361.181 of the Texas Health and Safety Code or on the National Priorities List pursuant to the Comprehensive Environmental Response Compensation and Liability Act, 42 United States Coade Annotated, 9601 et seq., as amended.

SURFACE TENSION: The free energy produced in a liquid surface by the unbalanced inward pull exerted by molecules underlying the layer of surface molecules.

SURFACE WATER: Water on the earth's surface exposed to the atmosphere, e.g., rivers, lakes, streams, oceans, ponds, reservoirs, etc.

SUSPENDED WATER: Water in the zone of aeration which includes seeping water and stored water.

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TEXAS CLEAN RIVERS ACT: Senate Bill 818; the legislation requiring the assessment of water quality on a basin-by-basin basis.

THERMAL POLLUTION: The degradation of water quality by the introduction of a heated effluent. It is primarily the result of the discharge of cooling waters from industrial processes, particularly from electrical power generation. ``Waste heat eventually results from virtually every energy conversion.

THERMAL CHIMNEY: A section of a building where solar hear or thermal currents are controlled in a manner that stimulates an updraft and the exhaust of heated air. This draws in fresh air to occupied areas of the building through open windows or vents and is a passive cooling method.

THERMAL ENVELOPE: The shell of a building that essentially creates a barrier from the elements. A highly insulated thermal envelope allows maximum control of interior temperatures with minimal outdoor influence.

THERMAL MASS: Materials that absorb hear or coolness and store if for a long period of time. Water and masonry materials can provide thermal mass. Such materials react slowly to temperature variations and are important aspects of any passive heating or cooling system.

TIDAL POWER: A form of power obtained from the filling and emptying of a bay or an estuary that can be closed by a dam. The enclosed basin is allowed to fill and empty only during brief periods at high and low tides in order to develop as much power as possible.

TIDES: The rise and fall of the surface of oceans, seas, bays, rivers, and other water bodies caused by the gravitational attraction of the moon and sun occurring unequally on different parts of the earth.

TITRANT: A solution of known strength or concentration; used in titration.

TITRATION: A process whereby a solution of known strength (titrant) is added to a certain volume of treated sample containing an indicator. A color change shows when the reaction is complete.

TITRATOR: An instrument, usually a calibrated cylinder (tube-form), used in titration to measure the amount of titrant being added to the sample.

TOTAL DISSOLVED SOLIDS : The amount of material (inorganic salts and small amounts of organic material) dissolved in water and commonly expressed as a concentration in terms of milligrams per liter. The term is equivalent to the term filterable residue, as used in the publication entitled Standard Methods for the Examination of Water and Wastewater.

TOTAL SUSPENDED SOLIDS: Total suspended matter in water, which is commonly expressed as a concentration in terms of milligrams per liter. The term is equivalent to the term nonfilterable residue, as used in the publication entitled Standard Methods for the Examination of Water and Wastewater.

TOTAL TOXICITY: Toxicity as determined by exposing aquatic organisms to samples or dilutions of instream water or treated effluent. Also referred to as whole~flluent toxicity.

TOXIC MATERIALS: Any liquid, gaseous, or solid substance or substances in a concentration which, when applied to, discharged to, or deposited in the waters in the state, may exert a poisonous effect detrimental to man or to the propagation, cultivation or conservation of animals, fish, or other aquatic life.

TOXICITY: The occurrence of lethal or sublethal adverse effects on representative, sensitive organisms due to exposure to toxic materials. Adverse effects caused by conditions of temperature, dissolved oxygen, or nontoxic dissolved substances are excluded from the definition of toxicity.

TRACE: The amount of rainfall or other form of precipitation which occurs when the quantity is so small that it cannot be measured in the rain gage.

TRACS : The TWC Regulatory Activities and Compliance System. A relational database developed in the Ingris system which integrates with the TWC GIS system to provide a total data management system for the State.

TRANSPIRATION: The process by which water vapor escapes from the living plant, principally the leaves, and enters the atmosphere.

TRIBUTARY: 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.

TROPICAL HARDWOOD: Wood products harvested from tropical rain forests. Tropical forests are not being harvested in a well-managed manner except in a few isolated cases. Certification efforts indicating sustainably harvested woods are just beginning.

TROPOSPHERE: The layer of atmosphere closest to the earth, extending seven to ten miles above the earth. It usually contains clouds and moisture.

TURBINE: A propeller or wheel device driven by the pressure of liquid or gas.

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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, ¤307.10 of Title 31 (relating to definitions).

UNDERGROUND STORAGE TANK: Any one or combination of underground tanks and any connecting underground pipes used to contain an accumulation of regulated substances, the volume of which, including the volume of the connecting underground pipes, is 10 percent or more beneath the surface of the ground.

UNILATERAL ADMINISTRATIVE ORDER(UAO): A legally binding document issued by EPA directing the parties potentially responsible to perform site cleanups or studies (generally, EPA does not issue unilateral orders for site studies).

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VALLEY: An area of land that is lower than the land on either side of it. Sometimes a stream may run through it.

VAPOR RETARDER : A continuous plastic membrane which surrounds the entire thermal envelope of a house and prevents moisture penetration into the wall cavity. This is generally not required in the Austin climate for moisture control, but may serve as an effective air infiltration barrier.

VAPOR: The word vapor is frequently used to describe a substance which, though now in a gaseous phase, generally exists as a solid or liquid at room temperature.

VAPORIZATION: The change of a substance from a liquid or solid state to the gaseous state.

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 drainage basin.

VOLATILE ORGANIC COMPOUNDS (VOCs): VOCs are made as secondary petrochemicals They include light alcohols, acetone, trichloroethylene, percholoroethylene, dichloroethylene, benzene, vinyl chloride, toluene, and methylene chloride. These potentially toxic chemicals are used as solvents, degreasers, paints, thinners, and fuels. Because of their volatile nature, they readily evaporate into the air, increasing the potential exposure to humans. Due to their low water solubility, environmental persistence, and widespread industrial use, they are commonly found in soil and ground water.

VOLCANIC WATER: Juvenile water (new water) furnished by lava flows and volcanic activity.

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WASTE WATER: Water for which disposal is more economical than use at the time and point of its occurrence. Waste water to one user may be a desirable supply to the same or another user at a different location. It may be waste water because of its quality, quantity, or the time of its occurrence.

WASTE HEAT : Heat that escapes to the atmosphere during combustion processes. Minimizing and recapturing waste heat is a valuable energy conserving strategy. For example, in homes there is heat in graywater, flues from wood-burning stoves, and heat pump fluids that can be captured for other uses such as preheating domestic hot water.

WASTE WATER TREATMENT: Water that is discharged from homes and businesses from sinks, toilets, washers, showers, etc. It is treated through a series of separation and aeration processes. A small amount of chlorine is added to Austin's wastewater before it enters the Colorado River.

WATER CYCLE: The process by which water travels in a sequence from the air (condensation) to the earth (precipitation) and returns to the atmosphere (evaporation). It is also referred to as the hydrologic cycle.

WATER FLOW: The rate of flow of water measured in volume and time.

WATER LAW: A law that has been instigated to control the right to the use of water.

WATER LEVEL: The water surface elevation of a particular water body.

WATER LOSSES: Water which is unavailable or lost from a particular containment system.

WATER POLLUTION: Industrial and institutional wastes, and other harmful or objectionable material in sufficient quantities to result in a measurable degradation of the water quality.

WATER QUALITY STANDARD: A plan for water quality management containing four major elements: water use; criteria to protect uses; implementation plans; and enforcement plans. An anti-degradation statement is sometimes prepared to protect existing high quality waters.

WATER QUALITY: A term used to describe the chemical, physical, and biological characteristics of water with respect to its suitability for a particular use.

WATER RIGHT: A legally protected right, granted by law, to take possession of water occurring in a water supply and to divert the water and put it to beneficial use.

WATER SPREADING: The retention of water behind dams or in basins; maintenance of flow in ditches or stream channels, or infusion of water into wells and shafts to develop influent seepage.

WATER SUPPLY SYSTEM: The system for the collection, storage, treatment and distribution of potable or other kinds of water from the sources of supply to the consumer.

WATER SUPPLY: Any quantity of available water.

WATER TABLE: The upper surface of a zone of saturation; the upper surface of the ground water.

WATER WELL REPORT: A report which a water well contractor or landowner who is constructing his own well submits to a water resources department. It includes the location and dimensions of the well, its flow, a record of geologic materials encountered in drilling, the temperature of the ground water, and other data.

WATER WHEEL: A device such as an turbine or similar engine to transform the energy of flowing water into mechanical power.

WATER WITCH: A person who predicts the presence of underground water with hand-held tools such as forked twigs or metal rods. The United States Geological Survey and the National Water Well Association do not advise against using a water witch to search for ground water, but say that there is no scientific basis for the belief in water witchery.

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 30,1979 is called the1979 Water Year.

WATER BUDGET: This is the calculated amount of water a household should use based on the type and number of fixtures, landscape requirements, and size of family. ECSD's Water Conservation Program can assist in developing the budget.

WATER CONSERVING IRRIGATION SYSTEM: Drip irrigation, soaker hoses, bubblers, and low-trajectory spray heads for water distribution; zoning irrigation for different water-demand plant types; electronic timers with five-day programming and rain override devices; irrigation schedules for early morning watering every five to seven days; soil moisture sensors.

WATER QUALITY MANAGEMENT PROGRAM: The Commission's overall program for attaining and maintaining water quality consistent with the state standards, as authorized under the Texas Water Code, the Texas Administrative Code, ad the Clean Water Act, Sections 1~, 2050), 208,303(e) and 314.

WATER: The liquid that descends from the clouds as rain; forms streams, lakes, and seas, and is a major constituent of all living matter; is an odorless, tasteless, colorless, very slightly compressible liquid.

WATERCOURSES: Depressions formed by runoff moving over the surface of the earth; any natural course that carries water.

WATERFALL: A sudden, nearly vertical drop in a stream, as it flows over rock.

WATERMASTER: An employee of a water department who distributes available water supply at the request of water right holders and collects hydrographic data.

WATERSHEDS ASSESSMENTS PROGRAM : The program implementing the assessments mandated by the Texas Clean Rivers Act (SB818).

WATERSHED: The area of land that contributes surface runoff to a given point in a drainage system.

WALT : A unit of powder indicating the rate at which work is done. The faster an agent can do work the more powerful it is, therefore, the higher its wattage.

WAVE MACHINE: A device used for converting the energy of ocean waves into electrical energy. It can also make waves at a water recreation site for swimming or surfing.

WAVE: A regular movement on a surface or within a material when energy travels through it. On the surface of an ocean or body of water, it is usually in the form of a curving swell or ridge.

WEATHER: The composite condition of the near earth atmosphere, which includes barometric pressure, wind, humidity, clouds and precipitation. Weather variations over a long period create the climate.

WELL DRILLERS: Individuals who have the equipment and ability to drill or dig wells.

WELL LOGS: A record that is kept during well drilling of the various formations and rock materials and the depths at which they are encountered.

WET COOLING: A type of cooling system which uses the evaporation of water to help dissipate excess heat.

WETLANDS: An area (including swamp, marsh, bog, prairie pothole, or similar area) having a predominance of hydric soils that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support and that under normal circumstances supports the anaerobic condition that supports the growth and regeneration of hydrophytic vegetation. The term Òhydric soilÓ means soil that, in its undrained condition, is saturated, flooded, or pended long enough during a growing season to develop an anaerobic condition that supports the growth and regeneration of hydrophytic vegetation. The term hydrophytic vegetation means a plant growing in: water or a substrate that is at least periodically deficient in oxygen during a growing season as a result of excessive water content. The term wetland does not include irrigated acreage used as farmiand; a man-made wetland of less than one acre; or a man-made wetland not constructed with wetland creation as a stated objective, including but not limited to an impoundment made for the purpose of soil and water conservation which has been approved or requested by soil and water conservation districts.

WIND MACHINE: A machine that generates electricity by the wind turning a generator-connected wind propeller. Austin is not a prime area for wind machines due to low annual wind speeds. However, new models that perform at lower wind speeds are becoming available.

WIND: Moving air.

WINDWALLS: These are small outside walls on a building set perpendicular to an exterior wall with windows on the side of the wingwall. A negative pressure zone is created by the wingwalls stimulating air movement through the windows.

WORK PLAN : A document outlining the proposed scope of work, including a time schedule id cost expenditures, from the river authority or designated local government to perform a service.

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XERISCAPE: 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 maintenance.

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YIELD: 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 ground water sources on a watershed.

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ZONE OF AERATION: A region in the earth above the water table. Water in the zone of aeration is under atmospheric pressure and would not flow into a well.

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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 ground water.

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