Precipitation containing harmful amounts of nitric and sulfuric acids formed primarily by nitrogen oxides and sulfur oxides released into the atmosphere when fossil fuels are burned.

Acidic Soil

A soil with low pH is considered acidic. Some plants respond well to acidic soils.

Adhesion

Attachment between two substances different in nature is adhesion.

Adsorption

Adsorption refers to the accumulation of molecules of a gas or liquid on the surface of another substance without penetration.

Aeration Zone

The unsaturated zone just above the water table is the aeration zone.

Aeration

Aeration is the process by which the area of contact between water and air is increased, either by natural methods or by mechanical devices.

Aerobic

Occurring or living in the presence of oxygen.

Aerobic Bacteria

The bacterium that needs oxygen to thrive and helps in the degradation of organic conditions is aerobic bacteria.

Aerobic Treatment

It is the process in which aerobic microbes break the composition of organic contaminants for survival and regenerating their population.

Agricultural Land

Land that is used for the production of agricultural crops and livestock farming is termed as agricultural land.

Agrochemical

It refers mainly to the pesticides and fertilizers used for agricultural purposes.

Algae

Microscopic plants usually found in aquatic environments, which are capable of photosynthesis.

Alkali

Chemicals with high pH are alkaline in nature and are refers as alkalis. They form soluble soaps with fatty acids and are used to neutralize acidic solutions.

Alluvial soils

Highly fertile soils washed down by run off from rivers and streams.

Altitude

Height above sea level that is used to define the elevation of places.

Ambient Temperature

The temperature of the surrounding cooling medium, such as gas or liquid.

Ammonia

A colorless, pungent, gas (NH3) that is extremely soluble in water and is considered suitable for fertilization.

Ammonium

A form of nitrogen that is available to plants. It is found in fertilizer, and is one of the first forms of nitrogen released as crop residues and organic fertilizers decay.

Ammonium Fixation

The adsorption or absorption of ammonium ions by the mineral or organic fractions of the soil in such a way that the ions are relatively insoluble in water and relatively unexchangeable by the usual methods of cation exchange.

Amoeba

A single celled organism of protozoan family that exists in fresh and salt water.

Anaerobic

Anaerobic refers to occurring or living without oxygen present.

Anhydrous Ammonia

Anhydrous ammonia is a compound formed by the combination of gaseous nitrogen and hydrogen.

Animal unit

The equivalent of 1,000 pounds of live animal weight makes one animal unit.

Aquaculture

Farming of plants and water that live in water.

Aquatic

Growing or living in water.

Aquatic life

Any life, animal or plant that grows and thrives in water.

Aquifer

An aquifer is an underground geological formation or group of formations that contain water, a source of ground water for wells and springs.

Arid

Lack or limited amounts of life-promoting moisture generates an arid atmosphere.

Artesian Aquifer

A confined aquifer in which groundwater rises in a well above the point at which it is naturally found in the aquifer, due to artesian pressure.

Artesian well

A well drilled into a confined aquifer with enough hydraulic pressure for the water to flow to the surface without pumping.

Artesian zone

A zone where water is confined in an aquifer under pressure so that the water will rise in the well above the bottom of the confining layer.

Aseptic

Free from bacterial contamination.

Assimilation

The ability of water to purify itself of pollutants.

Atmosphere

The envelope of air surrounding the earth.

Atmospheric Deposition

Pollution from the atmosphere associated with dry deposition in the form of dust, wet deposition in the form of rain and snow, or as a result of vapor exchanges.

Atmospheric Pressure

The pressure of the atmosphere at a specified place and time.

Atmospheric Transport

The movement of air pollutant from one place to the other by wind.

Atom

The smallest particles of an element that can exist either alone or in combination, considered a source of vast potential energy.

Atomic number

The number of protons in the nucleus of an atom.

Autotrophic

Self-nourishing organisms with the ability to synthesize organic molecules from CO2 using either photosynthesis or chemosynthesis.

Absorption bed

A pit containing coarse aggregate that absorps the effluents from a septic tank.

Back Pressure

Pressure exerted backward; in a field of fluid flow, a pressure exerted contrary to the pressure producing the main flow.

Backflow

A reverse flow of water or other liquids into the water supply pipes, caused by negative pressure in the pipes.

Bacteria

Single-celled organisms, free-living or parasitic, that break down the wastes and bodies of dead organisms, making their components available for reuse by other organisms.

Baseflow

Water that, having infiltrated the soil surface, percolates to the ground water table and moves laterally to reappear as surface runoff.

Basin

The entire geographical area drained by a river and its tributaries.

Bay

An indentation of a shoreline larger than a cove but smaller than a gulf.

Bedrock

The solid rock that underlies all soil or other loose material; the rock material that breaks down to eventually form soil.

Benthic zone

The bottom of a body of water or in the bottom sediments.

Best Management Practices

An agricultural practice that has been determined to be an effective, practical means of preventing or reducing nonpoint source pollution.

Bicarbonates

A salt of carbonic acid, having an HCO3 group, such as sodium bicarbonate.

Bioaccumulation

The uptake of chemical substances from the environment or food, their concentration and retention by organisms.

Bioavailability

The availability of chemicals to potentially biodegradative microorganisms.

Biochemical

It relates to the chemistry of living organisms and the changes that occur.

Biocide

Substances such as antibiotics, bacterialcides, or fungicides that are capable of destroying living organisms.

Biodegradable

Able to be broken down into basic compounds by micro-organisms.

Biodegradation

Transformation of a substance into new compounds through biochemical reactions or the actions of microorganisms such as bacteria.

Biogas

The gas produced from the anaerobic decomposition of organic material in a landfill.

Biological Contaminants

Contamination caused by living organisms either microscopic or larger animals, which can cause health effects.

Biological Control

The use of organisms or viruses to control parasites, weeds, or other pests.

Biological Diversity

The variety of life forms in a given area. Diversity can be categorized in terms of the number of species, the variety in the area's plant and animal communities, the genetic variability of the animals, or a combination of these elements.

Biological Growth

The growth of all organisms.

Biological Integrity

The ability of an aquatic ecosystem to support and maintain a balanced, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of natural habitats within a region.

Biological Oxidation

Decomposition of organic materials by microorganisms.

Biological Oxygen Demand

The amount of oxygen required by aerobic biological processes to break down the organic matter in water. BOD is a measure of the pollutional strength of biodegradeable waste on dissolved oxygen in water.

Biomass

The amount of living matter, in the form of organisms, present in a particular habitat, usually expressed as weight per unit area.

Biosphere

The part of the earth and its atmosphere in which living organisms exist or that is capable of supporting life; (2) the living organisms and their environment composing the biosphere.

Biota

The animal and plant life of a region or period.

Biotic

Belonging to life and living organisms

Black Ice

Thin, new ice on fresh or salt water that appears dark in color because of its transparency. Also refers to thin, transparent ice on road surfaces.

Black Water

Surface water that is dark in color because it contains high levels of colored organic acids such as tannic acid, or (2) domestic wastewater that contains animal, human, or food wastes.

Bloom

A visible abundance of microorganisms, generally referring to the excessive growth of algae or cyanobacteria at the surface of a body of water.

Blue-green Algae

Algae that are often associated with problem blooms in lakes. Some produce chemicals toxic to other organisms, including humans. They often form floating scum as they die. Many can fix nitrogen (N2) from the air to provide their own nutrient.

Bog

A poorly drained, wet area with very acidic (ph 4.0 or less), peaty soil. Bogs receive little or no ground water influence and support vegetation such as sedges, mosses, orchids and black spruce.

Boulder

A very large piece of rock.

Bound Water

Water which has become adsorbed to the surfaces of solid particles or grains. Under natural conditions, this water is viscous like and immobile but might not have lost its electrolytic properties. See also adsorption and water wet.

Brackish Water

Having a salinity between that of fresh and sea water.

Brackish Ice

Ice formed from brackish water.

Brine

Water with very high salt content.

Brownian Movement

Random motion of particle in a suspension of water of gas.

Buffer Strips

A vegetative barrier between waterways and land that is designed to prevent sediment loss from surface runoff.

Buffer Zone

An area adjacent to a wetland which protects wetland function and minimizes adverse impacts of upland development on wetland function.

Bulk Density

The weight of a material per unit of volume compared to the weight of the same volume of water.

Byproduct

Material, other than the principal product, that is generated as a consequence of an industrial process.

Detention Pond

A pond to collect and temporarily store stormwater runoff. Pollutants are allowed to settle out, and the water is then gradually released to surface waters.

Evapotranspiration

The total amount of water that is transferred from the earth's surface to the atmosphere. It is made up of the evaporation of liquid or solid water plus the transpiration from plants

Hydraulic Gradient

The slope of the water table or aquifer. The hydraulic gradient influences the direction and rate of groundwater flow.

Hydrologic Cycle

Often called the water cycle, it is the vertical and horizontal transport of water in all its states between the earth, the atmosphere, and the seas.

Infiltration

The downward entry of water through the soil surface into the soil. Infiltration constitutes the sole source of water to sustain the growth of vegetation and it helps to sustain the ground water supply to wells, springs, and streams. The rate of infiltration is influenced by the physical characteristics of the soil, soil cover (i.e. plants), water content of the soil, soil temperature, and rainfall intensity. The terms infiltration and percolation are often used interchangeably.

Ocean Discharge Waiver

A variance from Clean Water Act requirements for discharges into marine waters.

Odor Threshold

The minimum odor of a water or air sample that can just be detected after successive dilutions with odorless water. Also called threshold odor.

Off-Site Facility

A hazardous waste treatment, storage or disposal area that is located away from the generating site.

On-Site Facility

A hazardous waste treatment, storage or disposal area that is located on the generating site.

Oral Toxicity

Ability of a pesticide to cause injury when ingested.

Organic Matter

Carbonaceous waste contained in plant or animal matter and originating from domestic or industrial sources.

Organism

Any form of animal or plant life.

Organophosphates

Pesticides that contain phosphorus; short-lived, but some can be toxic when first applied.

Organophyllic

A substance that easily combines with organic compounds.

Osmosis

The passage of a liquid from a weak solution to a more concentrated solution across a semipermeable membrane that allows passage of the solvent (water) but not the dissolved solids.

Overdraft

The pumping of water from a groundwater basin or aquifer in excess of the supply flowing into the basin; results in a depletion or "mining" of the groundwater in the basin.

Overflow Rate

One of the guidelines for design of the settling tanks and clarifers in a treatment plant; used by plant operators to determine if tanks and clarifiers are over or under-used.

Overland Flow

A land application technique that cleanses waste water by allowing it to flow over a sloped surface. As the water flows over the surface, contaminants are absorbed and the water is collected at the bottom of the slope for reuse.

Oxidant

A collective term for some of the primary constituents of photochemical smog.

Oxidation Pond

A man-made (anthropogenic) body of water in which waste is consumed by bacteria, used most frequently with other waste-treatment processes; a sewage lagoon.

Oxidation

The chemical addition of oxygen to break down pollutants or organizac waste; e.g., destruction of chemicals such as cyanides, phenols, and organic sulfur compounds in sewage by bacterial and chemical means.

Organic contaminants

Organic chemicals which are toxic to organisms; they may be persistent and mobile in the environment.

Oxygen demand

The need for molecular oxygen to meet the needs of biological and chemical processes in water, even though very little oxygen will dissolve in water, it is extremely important in biological and chemical processes

Palustrine

Relating to a freshwater environment, such as a marsh, fen, lake, pond, river, bog or swamp.

Parasite, parasitic

Organisms that are pathogens and are obliged to live on or in other organisms, often causing disease or death.

Particulate

Consisting of many small individual particles, not dissolved.

Pathogen

An organism, generally a microorganism, causing, or capable of causing, disease or death, a disease-producing agent, usually applied to a living organism, any worms, protozoan, viruses, bacteria or fungi that cause disease.

Pathogenic

Causing, or capable of causing, disease or death, generally applied to microorganisms.

Peak flow

The maximum instantaneous discharge of a stream or river at a given location, usually occurs at or near the time of maximum height.

Peat Land

A wetland such as a fen or bog that accumulates peat and whose vegetation is dominated by sphagnum moss and small herbs.

Percolation

The movement of water downward and radially through subsurface soil layers, usually continuing downward to ground water. Can also involve upward movement of water.

Permeability

The rate at which liquids pass through soil or other materials in a specified direction.

An expression of the intensity of the basic or acid condition of a liquid; may range from 0 to 14, where 0 is the most acid and 7 is neutral.

Photic zone

The upper portion of the water column which admits sufficient light for photosynthesis, the photic zone is reduced with increased turbidity.

Photosynthesis

The manufacture by plants of carbohydrates and oxygen from carbon dioxide mediated by chlorophyll in the presence of sunlight.

Phytoplankton

The photosynthetic portion, primarily algae, of the free-floating community of small, mostly microscopic, organisms in water, collectively called plankton.

Plankton

The total free-floating community of small, mostly microscopic, organisms in water, some are motile but all are at the mercy of water currents.

Precipitation

Water, normally in the form or rain, snow and hail, which falls from the atmosphere to the earth as part of the water cycle, the process whereby solids or particle come out of solution.

Planktonic

Drifting unattached in water, the plankton include both plants and animals ranging from
microscopic to macroscopic.

Plume

A visible or measurable discharge of a contaminant from a given point of origin. Can be visible or thermal in water, or visible in the air as, for example, a plume of smoke.

Point source pollution

Source of pollution that involves discharge of wastes from an identifiable point.

Pollutant

Generally, any substance introduced into the environment that adversely affects the usefulness of a resource or the health of humans, animals, or ecosystems.

Pollution

Generally, the presence of a substance in the environment that because of its chemical composition or quantity prevents the functioning of natural processes and produces undesirable environmental and health effects.

Pollution Prevention

Identifying areas, processes, and activities which create excessive waste products or pollutants in order to reduce or prevent them through, alteration, or eliminating a process.

Portal-of-Entry Effect

A local effect produced in the tissue or organ of first contact between a toxicant and the biological system.

Pond

A relatively small, sometimes ephemeral or seasonal, inland body of fresh water occupying basin or hollow in the earth's surface.

Pore water

The water found in the interstices of submerged sediments, the basis of some types of toxicity testing, since it is pore water to which benthic organisms are exposed.

Porosity

Degree to which soil, gravel, sediment, or rock is permeated with pores or cavities through which water or air can move.

Porous

A material which allows water to pass through it.

Potable

Water that is toxicologically and pathologically safe and aesthetically fit to drink.

ppb

A concentration unit of chemical constituents in solution; the weight of solute per unit volume of solvent, usually water, one thousand micrograms per liter is equivalent to 1 milligram per litre, this measure is equivalent to parts per billion.

ppm

A concentration unit of chemical constituents in solution; the weight of solute per unit volume of solvent, usually water, one thousand milligrams per liter is equivalent to 1 gram per litre, this measure is equivalent to parts per million.

ppt

A concentration unit of chemical constituents in solution; the weight of solute per unit volume of solvent, usually applied to marine, brackish or saline water, this measure is equivalent to parts per thousand.

Primary Waste Treatment

First steps in wastewater treatment; screens and sedimentation tanks are used to remove most materials that float or will settle. Primary treatment removes about 30 percent of carbonaceous biochemical oxygen demand from domestic sewage.

Pristine

Describes a natural system, water for example, that has not been affected by anthropogenic pollution.

Profundal zone

The deep-water region of a lake that is not penetrated by sunlight.

Protozoan

Single-celled, nucleated, eukaryotic organisms, lacking cell walls, generally microscopic, some are photosynthetic.

Product Water

Water that has passed through a water treatment plant and is ready to be delivered to consumers.

Public Water System

A system that provides piped water for human consumption to at least 15 service connections or regularly serves 25 individuals.

Qualitative Use Assessment

Report summarizing the major uses of a pesticide including percentage of crop treated, and amount of pesticide used on a site.

Quality Assurance

A system of procedures, checks, audits, and corrective actions to ensure that all EPA research design and performance, environmental monitoring and sampling, and other technical and reporting activities are of the highest achievable quality.

Recharge

The process by which water is added back to the saturated zone from the soil surface.

Runoff

Precipitation that falls to the ground in the form of a liquid.

Reverse osmosis

A process for the removal of dissolved ions from water, in which pressure is used to force the water through a semi-permeable membrane, which will transmit the water by reject most other dissolved materials.

Riparian zone

A stream and all the vegetation on its banks out to the high water mark, associated with the bank of a watercourse, the woodlands bordering a river.

River

A relatively large and usually permanent flowing body of fresh water, in a defined channel.

Raw Sewage

Untreated wastewater and its contents.

Raw Water

Intake water prior to any treatment or use.

Reaeration

Introduction of air into the lower layers of a reservoir.

Recarbonization

Process in which carbon dioxide is bubbled into water being treated to lower the pH.

Recharge Area

A land area in which water reaches the zone of saturation from surface infiltration, e.g., where rainwater soaks through the earth to reach an aquifer.

Recharge Rate

The quantity of water per unit of time that replenishes or refills an aquifer.

Reclamation

Restoration of materials found in the waste stream to a beneficial use which may be for purposes other than the original use.

The maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on human health would occur, and that includes an adequate margin of safety.

Recycle/Reuse

Minimizing waste generation by recovering and reprocessing usable products that might otherwise become waste.

Restoration

Measures taken to return a site to pre-violation conditions.

Riparian Habitat

Areas adjacent to rivers and streams with a differing density, diversity, and productivity of plant and animal species relative to nearby uplands.

Risk Assessment

Qualitative and quantitative evaluation of the risk posed to human health and/or the environment by the actual or potential presence and/or use of specific pollutants.

Risk Management

he process of evaluating and selecting alternative regulatory and non-regulatory responses to risk.

River Basin

The land area drained by a river and its tributaries.

Receiving waters

A river, ocean, stream or other watercourse into which wastewater or treated effluent is discharged.

Reclaimed wastewater

Treated wastewater that can be used for beneficial purposes, such as irrigating certain plants, domestic wastewater which has been treated to a quality suitable for a beneficial use.

Recycled water

Water that is used more than once before it returns to the natural hydrologic system.

Reservoir

Any natural or artificial holding area used to store, regulate, or control water.

Residence time

The period of time water is retained in a reservoir, bay or other system, based upon flow rates into and out of the system.

Return flow

Unconsumed water which returns to its source or some other water body after its diversion as surface water or its extraction from the ground.

Silviculture

Management of forest land for timber.

Safe Water

Water that does not contain harmful bacteria, toxic materials, or chemicals, and is considered safe for drinking even if it may have taste, odor, color, and certain mineral problems.

Safe Yield

The annual amount of water that can be taken from a source of supply over a period of years without depleting that source beyond its ability to be replenished naturally in "wet years."

Salinity

The percentage of salt in water.

Salt Water Intrusion

The invasion of fresh surface or ground water by salt water. If it comes from the ocean it may be called sea water intrusion.

Salts

Minerals that water picks up as it passes through the air, over and under the ground, or from households and industry.

Salvage

The utilization of waste materials.

Sand Filters

Devices that remove some suspended solids from sewage. Air and bacteria decompose additional wastes filtering through the sand so that cleaner water drains from the bed.

Sanitary Water

Water discharged from sinks, showers, kitchens, or other non-industrial operations, but not from commodes.

Saturated Zone

The area below the water table where all open spaces are filled with water under pressure equal to or greater than that of the atmosphere.

Saturation

The condition of a liquid when it has taken into solution the maximum possible quantity of a given substance at a given temperature and pressure.

Secondary Treatment

The second step in most publicly owned waste treatment systems in which bacteria consume the organic parts of the waste. It is accomplished by bringing together waste, bacteria, and oxygen in trickling filters or in the activated sludge process.

Sediment Yield

The quantity of sediment arriving at a specific location.

Sedimentation

Letting solids settle out of wastewater by gravity during treatment.

Sedimentation Tanks

Wastewater tanks in which floating wastes are skimmed off and settled solids are removed for disposal.

Sediments

Soil, sand, and minerals washed from land into water, usually after rain.

Seepage

Percolation of water through the soil from unlined canals, ditches, laterals, watercourses, or water storage facilities.

Semi-Confined Aquifer

An aquifer partially confined by soil layers of low permeability through which recharge and discharge can still occur.

Septic System

An on-site system designed to treat and dispose of domestic sewage.

Septic Tank

An underground storage tank for wastes from homes not connected to a sewer line. Waste goes directly from the home to the tank.

Settleable Solids

Material heavy enough to sink to the bottom of a wastewater treatment tank.

Settling Tank

A holding area for wastewater, where heavier particles sink to the bottom for removal and disposal.

Sewage

The waste and wastewater produced by residential and commercial sources and discharged into sewers.

Sewage Sludge

Sludge produced at a Publicly Owned Treatment Works, the disposal of which is regulated under the Clean Water Act.

Sewer

A channel or conduit that carries wastewater and storm-water runoff from the source to a treatment plant or receiving stream.

Sewerage

The entire system of sewage collection, treatment, and disposal.

Silt

Sedimentary materials composed of fine or intermediate-sized mineral particles.

Sink

Place in the environment where a compound or material collects.

Site Assessment Program

A means of evaluating hazardous waste sites through preliminary assessments and site inspections to develop a Hazard Ranking System score.

Slow Sand Filtration

Passage of raw water through a bed of sand at low velocity, resulting in substantial removal of chemical and biological contaminants.

Sludge

A semi-solid residue from any of a number of air or water treatment processes; can be a hazardous waste.

Slurry

watery mixture of insoluble matter resulting from some pollution control techniques.

Smog

Air pollution typically associated with oxidants.

Smoke

Particles suspended in air after incomplete combustion.

Soil Adsorption Field

A sub-surface area containing a trench or bed with clean stones and a system of piping through which treated sewage may seep into the surrounding soil for further treatment and disposal.

Soil and Water Conservation Practices

Control measures consisting of managerial, vegetative, and structural practices to reduce the loss of soil and water.

Soil Conditioner

An organic material like humus or compost that helps soil absorb water, build a bacterial community, and take up mineral nutrients.

Soil Erodibility

An indicator of a soil's susceptibility to raindrop impact, runoff, and other erosive processes.

Soil Gas

Gaseous elements and compounds in the small spaces between particles of the earth and soil. Such gases can be moved or driven out under pressure.

Soil Moisture

The water contained in the pore space of the unsaturated zone.

Sole-Source Aquifer

An aquifer that supplies 50-percent or more of the drinking water of an area.

Solid Waste

Non-liquid, non-soluble materials ranging from municipal garbage to industrial wastes that contain complex and sometimes hazardous substances.

Solid Waste Disposal

The final placement of refuse that is not salvaged or recycled.

Solid Waste Management

Supervised handling of waste materials from their source through recovery processes to disposal.

Tail Water

The runoff of irrigation water from the lower end of an irrigated field.

Temporary Wetlands

A wetland area in which water is present only for a part of the year.

Terrain

An area of ground, considered as to its extent and natural features, in relation to its use in a particular operation.

Terrace

Dikes built along the contour of sloping farm land that hold runoff and sediment to reduce erosion.

Thermal Pollution

Discharge of heated water from industrial processes that can kill or injure aquatic organisms.

Threshold

The dose or exposure level below which a significant adverse effect is not expected.

Tillage

Plowing, seedbed preparation, and cultivation practices.

Topography

The physical features of a surface area including relative elevations and the position of natural and man-made (anthropogenic) features.

Total Dissolved Phosphorous

The total phosphorous content of all material that will pass through a filter, which is determined as orthophosphate without prior digestion or hydrolysis. Also called soluble P. or ortho P.

Total Dissolved Solids

All material that passes the standard glass river filter; now called total filtrable residue. Term is used to reflect salinity.

Total Suspended Particles

A method of monitoring airborne particulate matter by total weight.

Total Suspended Solids

A measure of the suspended solids in wastewater, effluent, or water bodies, determined by tests for "total suspended non-filterable solids."

Toxic Pollutants

Materials that cause death, disease, or birth defects in organisms that ingest or absorb them. The quantities and exposures necessary to cause these effects can vary widely.

Toxic Substance

A chemical or mixture that may present an unreasonable risk of injury to health or the environment.

Toxic Waste

A waste that can produce injury if inhaled, swallowed, or absorbed through the skin.

Toxicity

The degree to which a substance or mixture of substances can harm humans or animals.

Transient Water System

A non-community water system that does not serve 25 of the same nonresidents per day for more than six months per year.

Transpiration

The process by which water vapor is lost to the atmosphere from living plants. The term can also be applied to the quantity of water thus dissipated.

Treated Wastewater

Wastewater that has been subjected to one or more physical, chemical, and biological processes to reduce its potential of being health hazard.

Treatment Plant

A structure built to treat wastewater before discharging it into the environment.

Trickle Irrigation

Method in which water drips to the soil from perforated tubes or emitters.

Trickling Filter

A coarse treatment system in which wastewater is trickled over a bed of stones or other material covered with bacteria that break down the organic waste and produce clean water.

Tundra

A type of treeless ecosystem dominated by lichens, mosses, grasses, and woody plants.

Turbidity

A cloudy condition in water due to suspended silt or organic matter.

Ultraviolet Rays

Radiation from the sun that can be useful or potentially harmful.

Unconfined Aquifer

An aquifer containing water that is not under pressure; the water level in a well is the same as the water table outside the well.

Underground Storage Tank

A tank located at least partially underground and designed to hold gasoline or other petroleum products or chemicals.

Unsaturated Zone

The area above the water table where soil pores are not fully saturated, although some water may be present.

Urban Runoff

Storm water from city streets and adjacent domestic or commercial properties that carries pollutants of various kinds into the sewer systems and receiving waters.

Vadose Zone

The zone between land surface and the water table within which the moisture content is less than saturation and pressure is less than atmospheric.

Vapor Pressure

A measure of a substance's propensity to evaporate, vapor pressure is the force per unit area exerted by vapor in an equilibrium state with surroundings at a given pressure.

Vegetative Controls

Non-point source pollution control practices that involve vegetative cover to reduce erosion and minimize loss of pollutants.

Viscosity

The molecular friction within a fluid that produces flow resistance.

Volatile

Any substance that evaporates readily.

Volatile Liquids

Liquids which easily vaporize or evaporate at room temperature.

Volatile Organic Compound

Any organic compound that participates in atmospheric photochemical reactions except those designated by EPA as having negligible photochemical reactivity.

Volatile Solids

Those solids in water or other liquids that are lost on ignition of the dry solids at 550° centigrade.

Waste Characterization

Identification of chemical and microbiological constituents of a waste material.

Waste Generation

The weight or volume of materials and products that enter the waste stream before recycling, composting, land filling, or combustion takes place. Also can represent the amount of waste generated by a given source or category of sources.

Waste Minimization

Measures or techniques that reduce the amount of wastes generated during industrial production processes; term is also applied to recycling and other efforts to reduce the amount of waste going into the waste stream.

Waste Reduction

Using source reduction, recycling, or composting to prevent or reduce waste generation.

Waste Treatment Lagoon

Impoundment made by excavation or earth fill for biological treatment of wastewater.

Waste Treatment Plant

A facility containing a series of tanks, screens, filters and other processes by which pollutants are removed from water.

Wastewater

The spent or used water from a home, community, farm, or industry that contains dissolved or suspended matter. Water Pollution: The presence in water of enough harmful or objectionable material to damage the water's quality.

Water Quality Criteria

Levels of water quality expected to render a body of water suitable for its designated use.

Water Quality Standards

State-adopted and EPA-approved ambient standards for water bodies.

Watershed

The specific land area that drains water into a river system or other body of water.

Water Solubility

The maximum possible concentration of a chemical compound dissolved in water. If a substance is water soluble it can very readily disperse through the environment.

Water Storage Pond

An impound for liquid wastes designed to accomplish some degree of biochemical treatment.

Water Table

The level of groundwater.

Water Treatment Lagoon

An impound for liquid wastes designed to accomplish some degree of biochemical treatment.

Watershed Approach

A coordinated framework for environmental management that focuses public and private efforts on the highest priority problems within hydrologically-defined geographic areas taking into consideration both ground and surface water flow.

Watershed Area

A topographic area within a line drawn connecting the highest points uphill of a drinking waterintake into which overland flow drains.

Well

A bored, drilled, or driven shaft, or a dug hole whose depth is greater than the largest surface dimension and whose purpose is to reach underground water supplies or oil, or to store or bury fluids below ground.

Well Injection

The subsurface emplacement of fluids into a well.

Well Monitoring

Measurement by on-site instruments or laboratory methods of well water quality.

Wetlands

An area that is saturated by surface or ground water with vegetation adapted for life under those soil conditions, as swamps, bogs, fens, marshes, and estuaries.

Wildlife Refuge

An area designated for the protection of wild animals, within which hunting and fishing are either prohibited or strictly controlled.

Xenobiota

Any biotum displaced from its normal habitat; a chemical foreign to a biological system.

Yield

The quantity of water (expressed as a rate of flow or total quantity per year) that can be collected for a given use from surface or groundwater sources.

Zero Air

Atmospheric air purified to contain less than 0.1 ppm total hydrocarbons.

Water Quality Home

Water-Quality Primer Home

KYWWC Home

Last Revised on: 11/20/2007