A

acid rain - Rainfall with a pH of less than 7.0. One source is the combining of rain and sulfur dioxide emissions which are a by-product of combustion of fossil fuels. Also referred to as acid deposition and wet deposition.

algae - Simple rootless plants that grow in sunlit waters in relative proportion to the amounts of nutrients available. They can affect water quality adversely by lowering the dissolved oxygen in the water. They are food for fish and small aquatic animals.

algae blooms - Rapid growth of algae on the surface of lakes, streams, or ponds; stimulated by nutrient enrichment.

alkali - Any strongly basic substance of hydroxide and carbonate, such as soda, potash, etc., that is soluble in water and increases the pH of a solution.

aquatic plant - Any plant growing in or closely associated with water.

aquifer - The underground layer of water-soaked sand and rock that acts as a water source for a well; described as artesian (confined) or water table (unconfined).

arid - Describes regions where precipitation is insufficient in quantity for most crops and where agriculture is impractical without irrigation.

Artesian well - A well from which water naturally flows from an underground aquifer because of subterranean pressure.

atmosphere - The layer of gases surrounding the earth and composed of considerable amounts of nitrogen, hydrogen, and oxygen.

atmospheric water - Water present in the atmosphere either as a solid (snow, hail), liquid (rain) or gas (fog, mist).

B

benthos - Aquatic plants or animals that live on or near the bottom of a water body.

bioaccumulation - Toxic substances that increase in concentration in the tissues and organisms of living organisms as they breathe contaminated air, drink contaminated water, or eat contaminated food. These substances are very slowly metabolized or excreted.

biodegradable - Capable of being broken down by living organisms into inorganic compounds.

biological concentration - The process by which toxic substances in the environment are taken up by organisms and move up the food chain. With each step up the chain, the concentration become higher in the tissues and organs of species that feed on organisms lower in the chain.

biological diversity (biodiversity) - The variety of different species, the genetic variability of each species, and the variety of different ecosystems that they form.

biological magnification - The process by which substances such as pesticides or heavy metals move up the food chain. Once introduced into the ecosystem, they are eaten by small organisms that in turn are eaten by larger animals and, eventually, may be eaten by humans. The substances bioaccumulate, that is, as they move up the food chain they become concentrated in animal tissues or internal organs.

biological oxygen demand (BOD) - The amount of oxygen required by aerobic biological processes to break down the organic matter in water. BOD is a measure of the pollution strength of biodegradable waste on dissolved oxygen in water.

biomagnification (biological magnification) - A cumulative increase in the concentrations of a persistent substance in successively higher levels of the food chain.

biota - Collectively, the plants, microorganisms, and animals of a certain area or region.

black water - (1) 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.

bog - A type of wetland that accumulates appreciable peat deposits. They depend primarily on precipitation for their water source, and are usually acidic and rich in plant matter with a conspicuous mat or living green moss.

bubble - In Florida's aquifers, a formation of fresh water that lies above areas of salt water. It is also called a lens. Bubbles are particularly vulnerable to saltwater intrusion if the fresh water is pumped out.

C

chemical oxygen demand (COD) - The amount of oxygen utilized in the chemical reactions that occur in water as a result of the addition of wastes. COD is a measure of the pollution strength of chemical waste on dissolved oxygen in water.

chlorination - Adding chlorine to drinking water, sewage, or industrial waste to disinfect or to oxidize undesirable compounds.

Clean Water Act (CWA) - Federal legislation administered by the U.S. EPA that serves as the primary means of protecting and regulating the surface water quality of the United States.

climate - Meteorological elements that characterize the average and extreme conditions of the atmosphere over a long period of time at any one place or region of the earth's surface.

climate change - The slow variations of climatic characteristics over time at a given place.

coliform bacteria - A group of bacteria used as an indicator of sanitary quality in water. Exposure to these organisms in drinking water causes diseases such as cholera.

combined sewers - A sewer that carries both sewage and storm water runoff.

condensation - The process by which a vapor becomes a liquid or solid; the opposite of evaporation. In meteorological usage, this term is applied only to the transformation from vapor to liquid.

conservation - The continuing protection and management of natural resources in accordance with principles that assure their optimum long-term economic and social benefits.

consumptive use - The difference between the total quantity of water withdrawn from a source for any use and the quantity of water returned to the source; e.g., the release of water into the atmosphere; the consumption of water by man, animals, and plants; and the incorporation of water into the products of industrial or food processing.

contaminant - Any physical, chemical, biological, or radiological substance or matter that has an adverse affect on air, water, or soil.

cooling tower - A structure that helps remove heat from water used as a coolant; e.g., in electric power generating plants.

cubic meter per second (m3/s) - A unit expressing rate of discharge, typically used in measuring stream flow. One cubic meter per second is equal to the discharge in a stream of a cross section one meter wide and one meter deep, flowing with an average velocity of one meter per second.

cultural eutrophication - The accelerated rate at which water bodies become eutrophic, or die, because of human-caused nutrient pollution.

D

dam - A structure of earth, rock, concrete, or other materials designed to retain water, creating a pond, lake, or reservoir.

delta - A fan-shaped alluvial deposit at a river mouth formed by the deposition of successive layers of sediment.

demand - The numerical expression of the desire for goods and services associated with an economic standard for acquiring them.

depletion - Loss of water from surface water reservoirs or groundwater aquifers at a rate greater than that of recharge.

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.

detritus - Loose fragments, particles, or grains that have been formed by disintegrating rocks; or dead organic material in the process of decomposition.

dioxin - Any of a family of compounds known chemically as dibenzo-p-dioxins. Concern about them arises from their potential toxicity and contamination in commercial products.

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 used to describe the flow of water from a pipe or from a drainage basin. Other words related to it are runoff, stream flow, and yield.

dissolved oxygen (DO) - The amount of oxygen freely available in water and necessary for aquatic life and the oxidation of organic materials.

dissolved solids (DS) - Very small pieces of organic and inorganic material contained in water. Excessive amounts make water unfit to drink or limits its use in industrial processes.

diversion - The transfer of water from a stream, lake, aquifer, or other source of water by a canal, pipe, well, or other conduit to another watercourse or to the land, as in the case of an irrigation system.

domestic use - The quantity of water used for household purposes such as washing, food preparation, and bathing.

dredging - The removal of mud from the bottom of water bodies using a scooping machine. This disturbs the ecosystem and causes silting that can kill aquatic life.

drought - A continuous and lengthy period during which no significant precipitation is recorded.

dry deposition - Emissions of sulfur and nitrogen oxides which, in the absence of water in the atmosphere (i.e., rain), settle to the ground as particulate matter.

dyke - An artificial embankment constructed to prevent flooding.

E

ecosystem - A system formed by the interaction of a group of organisms and their environment.

effluent - The sewage or industrial liquid waste which is released into natural water by sewage treatment plants, industry, or septic tanks.

emergent plant - In wetlands emergent plants have their "heads" above the water but are anchored in the marsh soils with thick roots or underground stems called rhizomes.

environment - All of the external factors, conditions, and influences which affect an organism or a community.

environmental impact assessment - The critical appraisal of the likely effects of a proposed project, activity, or policy on the environment, both positive and negative.

environmental monitoring - The process of checking, observing, or keeping track of something for a specified period of time or at specified intervals.

ephemeral stream - A stream or part of a stream that flows only after precipitation, and whose channel is always above the water table.

erosion - The wearing down or washing away of the soil and land surface by the action of water, wind or ice.

estuary - Regions of interaction between rivers and near shore ocean waters, where tidal action and river flow create a mixing of fresh and salt water. These areas may include bays, mouths of rivers, salt marshes, and lagoons. These brackish water ecosystems shelter and feed marine life, birds, and wildlife.

ethylene dibromide (EDB) - A toxic and carcinogenic chemical used as an agricultural fumigant and in some industrial processes. It has been banned in the United States for most agricultural uses. A number of Florida's rural drinking-water wells are contaminated with the chemical.

eutrophic lake - Shallow, murky bodies of water that have excessive concentrations of plant nutrients causing excessive algal production.

eutrophication - The natural process by which lakes and ponds become enriched with dissolved nutrients, resulting in increased growth of algae and other microscopic plants.

evaporation - The process by which a liquid changes to a vapor.

evapotranspiration - The loss of water from a land area through evaporation from the soil, and through plant transpiration.

exotic species - A plant or animal species that is not native to a geographic area or ecosystem. Because they may have no natural pests once they are placed in a new location, many exotic species reproduce prolifically and replace native species or the habitats that support those species.

F

fen - A type of wetland that accumulates peat deposits. Fens are less acidic than bogs, deriving most of their water from groundwater rich in calcium and magnesium.

flood - The temporary inundation of normally dry land areas resulting from the overflowing of the natural or artificial confines of a river or other body of water.

flood damage - The economic loss caused by floods, including damage by inundation, erosion, and/or sediment deposition. Damages also include emergency costs and business or financial losses. Evaluation may be based on the cost of replacing, repairing, or rehabilitating; or the comparative change in market or sales value; or on the change in the income or production caused by flooding.

flood forecasting - Prediction of stage, discharge, time of occurrence and duration of a flood, especially of peak discharge at a specified point on a stream, resulting from precipitation and/or snowmelt.

flood fringe - The land on which water is stored as dead water during flooding, and which does not contribute to the downstream passage of flow.

flood peak - The highest magnitude of the stage of discharge attained by a flood. Also called peak stage or peak discharge.

floodplain - Any normally dry land area that is susceptible to being inundated by water from any natural source. This area is usually lowland adjacent to a stream or lake.

flood proofing - Any combination of structural and nonstructural additions, changes, or adjustments to structures which reduce or eliminate flood damage.

floodway - The channel of a river or stream and those parts of the adjacent floodplain adjoining the channel which are required to carry and discharge the base flood.

flow - The rate of water discharged from a source; expressed in volume with respect to time, e.g., m3/s.

flow augmentation - The addition of water to a stream especially to meet instream flow needs.

food chain - A sequence of organisms, each of which uses the next, lower member of the sequence as a food source.

food web - The complex intermeshing of individual food chains in an ecosystem.

fresh water - Water that generally contains less than 1000 milligrams per liter of dissolved solids such as metals, nutrients, etc.

G

glacier - A huge mass of ice, formed on land by the compaction and re-crystallization of snow, that moves very slowly down slope or outward due to its own weight.

greenhouse effect - The warming of the earth's atmosphere caused by a build-up of carbon dioxide or other trace gases; it is believed by many scientists that this build-up allows light from the sun's rays to heat the earth but prevents a counterbalancing loss of heat.

groundwater - The supply of fresh water found beneath the earth's surface (usually in aquifers) which is often used for supplying wells and springs.

groundwater recharge - The inflow to an aquifer.

H

habitat - The native environment where a plant or animal naturally grows or lives.

hazardous waste - Waste that poses a risk to human health or the environment and requires special disposal techniques to make it harmless or less dangerous.

heavy metals - Metallic elements with high atomic weights, such as mercury, chromium, cadmium, arsenic, and lead. They can damage or kill living things even in low concentrations. Heavy metals can accumulate in the food chain and in sediments at the bottom of water bodies, where they can be stirred up by dredging.

herbicide - A chemical substance that controls or destroys plants, weeds, or grasses.

hydric soil - A soil that in its undrained condition is saturated, flooded, or pooled long enough during the growing season to develop anaerobic conditions that favor the growth and regeneration of hydrophytic vegetation (plants adapted to wet areas).

hydroelectricity - Electric energy produced by water-powered turbine generators.

hydrologic cycle - The constant circulation of water from the sea, through the atmosphere, to the land, and back to the sea by over-land, underground, and atmospheric routes.

hydrology - The science of waters of the earth; water's properties, circulation, principles, and distribution.

hypoxia - Low levels of dissolved oxygen in water, which usually result in fish kills and decrease plant growth.

I

infiltration - The movement of water into soil or porous rock. Infiltration occurs as water flows through the larger pores of rock or between soil particles under the influence of gravity, or as a gradual wetting of small particles by capillary action.

inflow - The entry of extraneous rain water into a sewer system from sources other than infiltration, such as basement drains, manholes, storm drains, and street washing.

injection well - A well that injects wastewater fluids into underground formations. Florida has five classes of injection wells, which are used to dispose of treated municipal effluent, stormwater, and industrial and hazardous wastes.

inorganic - Matter other than plant or animal, and not containing a combination of carbon/hydrogen/oxygen as in living things.

instream use - Uses of water within the stream channel; e.g., fish and other aquatic life, recreation, navigation, and hydroelectric power production.

integrated resource planning - The management of two or more resources in the same general area; commonly includes water, soil, timber, grazing land, fish, wildlife, and recreation.

interbasin transfer - The diversion of water from one drainage basin to one or more other drainage basins.

irrigation - The controlled application of water to cropland, hay-land, and/or pasture to supplement that supplied through nature.

K

karst - Water-soluble limestone, dolomite, and gypsum beds in which water has dissolved underground cavities, producing fissures, sinkholes, underground streams, and caverns. Florida has numerous karst formations

kilowatt (kW) - A unit of electrical power equal to 1000 watts or 1.341 horsepower.

kilowatt hour (kWh) - One kilowatt of power applied for one hour.

L

lagoon - (1) A shallow pond where sunlight, bacterial action, and oxygen work to purify wastewater. (2) A shallow body of water, often separated from the sea by coral reefs or sandbars.

lake - Any inland body of standing water, usually fresh water, larger than a pool or pond; a body of water filling a depression in the earth's surface.

leaching - The removal of soluble organic and inorganic substances from the topsoil downward by the action of percolating water.

limestone - Material composed mainly of calcium or magnesium carbonate.

liter - The basic unit of measurement for volume in the metric system; equal to 61.025 cubic inches or 1.0567 liquid quarts.

littoral zone - The shallow zone along the shoreline of a body of water, containing rooted plants that provide important habitat for other aquatic species.

M

macro invertebrate - Bottom-dwelling aquatic invertebrate animals large enough to be seen with the naked eye. They consist mainly of insects, shrimp, crayfish, clams, snails, and worms. The analysis of the quantity and type of macro invertebrate species is used as an indicator of water quality.

marsh - A type of wetland that does not accumulate appreciable peat deposits and is dominated by herbaceous vegetation. Marshes may be either fresh or salt water and tidal or non-tidal.

megawatt - A unit of electricity equivalent to 1000 kilowatts.

mesotrophic - Lakes with moderate quantities of nutrients, found in areas with more fertile soils, or where nutrients from stormwater runoff flow into lake water.

model - A simulation, by descriptive, statistical, or other means, of a process or project that is difficult or impossible to observe directly.

N

native species - Species native to a particular geographic area. Because they are part of an ecosystem where everything is interdependent, these species are adapted to local foods, soil and weather conditions, and pests and diseases.

natural flow - The flow of a stream as it would be if unaltered by upstream diversion, storage, import, export, or change in upstream consumptive use caused by development.

navigable waters - Traditionally, waters sufficiently deep and wide for navigation by all, or specific sizes of vessels.

nitrate - A nitrogen-containing compound that can exist in the atmosphere or as a dissolved gas in water. Nitrates are found in fertilizers, and human and animal wastes.

nitrogen - An element essential to the growth and development of plants; occurs in manure and chemical fertilizer and, in excess, can cause waters to become polluted by promoting excessive growth of algae and other aquatic plants.

nonpoint source pollution - Sources of water pollution not associated with a distinct discharge source; includes rainwater, erosion, runoff from roads, farms, and parking lots, and seepage from soil-based wastewater disposal systems.

non-renewable resources - Natural resources that can be used up completely or else used up to such a degree that it is economically impractical to obtain any more of them; e.g., coal, crude oil, metal ores.

nutrient - As a pollutant, any element or compound, such as phosphorus or nitrogen, that fuels abnormally high organic growth in aquatic ecosystems (e.g., eutrophication of a lake).

O

oligotrophic lake - Deep clear lakes with low nutrient supplies. They contain little organic matter and have a high dissolved oxygen level.

organic - (1) Referring to or derived from living organisms. (2) In chemistry, any compound containing carbon.

organism - A living thing.

oxygen demand - Chemical and biological oxygen demand (COD and BOD) are measures of the oxygen consumed when a substance degrades. Materials such as food waste and dead plant or animal tissue use up dissolved oxygen in the water when decomposed through chemical or biological processes.

P

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.

pathogenic microorganisms - Microorganisms that can cause disease in other organisms or in humans, animals, and plants.

percolation - The movement of water downward through the sub-surface to the zone of saturation.

pesticide - A substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Also, any substance or mixture of substances intended to regulate plant or leaf growth. Pesticides can accumulate in the food chain and/or contaminate the environment if misused.

pH - An expression of 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.

phosphorous (P) - An element essential to the growth and development of plants; occurs in manure and chemical fertilizer and, in excess, can cause waters to become polluted by promoting excessive growth of algae and other aquatic plants.

photosynthesis - The manufacture by plants of carbohydrates and oxygen from carbon dioxide and water in the presence of chlorophyll, using sunlight as an energy source.

phytoplankton - Usually microscopic aquatic plants, sometimes consisting of only one cell.

plankton - Tiny aquatic plants and animals that live in the open water of lakes and rivers, and that form the base of the ocean food chain.

point source pollution - A specific discharge that is traceable to a distinct source (pipe, ditch, container, well, etc.) such as those from wastewater treatment plants or industrial facilities.

pollutant - A contaminant that adversely alters the physical, chemical, or biological properties of the environment. The term includes toxic metals, carcinogens, pathogens, oxygen-demanding materials, heat, and all other harmful substances, contaminants, or impurities.

polychlorinated biphenyls (PCBs) - A group of chemicals found in industrial wastes.

pond - A small natural body of standing fresh water filling a surface depression, usually smaller than a lake.

precipitation - Water falling, in a liquid or solid state, from the atmosphere to a land or water surface.

primary standards - Regulatory standards that place limits on drinking-water contaminants posing a risk to health, including radiation, coliform bacteria, and sulfates.

primary treatment - The first of two stages in wastewater treatment. Screens and sedimentation tanks are used to remove most material that floats or that will settle.

Pumping station - A mechanical device in a sewer or water system or other pipeline that moves liquids to a higher level.

R

rain - Water falling to earth in drops that have been condensed from moisture in the atmosphere.

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

recharge - The processes involved in the addition of water to the zone of saturation; also the amount of water added.

reclaimed water - Water that has received at least secondary treatment and is reused after flowing out of a water treatment facility.

recyclable - Refers to such products as paper, glass, plastic, used oil, and metals that can be reprocessed instead of being disposed of as waste.

red tide - The proliferation of a toxic marine plankton that often causes fish kills and can contaminate certain edible shellfish. Red tide is a natural phenomenon that can be stimulated by the addition of nutrients.

renewable resource - Natural resource (e.g., tree biomass, fresh water, fish) whose supply can essentially never be exhausted, usually because it is continuously produced.

reservoir - A pond, lake, or basin (natural or artificial) that stores, regulates, or controls water.

resource - A person, thing, or action needed for living or to improve the quality of life.

retention pond - An artificial pond used to store stormwater so that it eventually recharges underground aquifers, instead of being released into surface waters.

riparian - Of, on, or pertaining to, the banks of a stream, river, or lake.

river - A natural stream of water of substantial volume.

river basin - The land area drained by a river and its tributaries.

runoff - Rainfall or other precipitation that is not absorbed by the soil, but drains off the land into streams, rivers, and other receiving waters.

S

Safe Drinking Water Act (SDWA) - Legislation to insure safe drinking water. Passed by Congress in 1974 and amended in 1986, it directs the EPA to establish and enforce water quality standards to protect public health.

salinity - Quality of water based on its salt content; sea-water contains approximately 18,000 parts per million of salt.

saltwater intrusion - The invasion of fresh surface or groundwater by salt water.

sanitary sewers - Underground pipes that carry off only domestic or industrial waste, not storm water.

saturated zone - An area under the ground in which all pores and cracks are filled with water under pressure equal to or greater than that of the atmosphere.

Secchi depth - A visual measure of water clarity, this is the depth at which the pattern on a Secchi disk containing black-and-white markings can no longer be distinguished under water.

secondary standards - Regulations for public drinking-water systems applying to esthetic contaminants that can affect water's odor or appearance, including hydrogen sulfide and total dissolved solids.

secondary treatment - The second step in publicly owned waste treatment systems, in which bacteria consume suspended organic matter through processes that bring waste, bacteria, and oxygen together.

sediment - particles of mud, sand, clay, silt, and organic matter transported and deposited by water.

sedimentation - The deposition of sediment from a state of suspension in water or air.

seiche - A periodic oscillation, or standing wave, in an enclosed water body the physical dimensions of which determine how frequently the water level changes.

septic tank - Tank used to hold domestic wastes when a sewer line is not available to carry them to a treatment plant; part of a rural on-site sewage treatment system.

sewage - The waste and wastewater produced by residential and commercial establishments and discharged into sewers.

sewage system - Pipelines or conduits, pumping stations, force mains, and all other structures, devices, and facilities used for collecting or conducting wastes to a point for treatment or disposal.

silt - Fine particles of sand or rock that can be picked up by the air or water and deposited as sediment.

silviculture - The management of forest lands for timber.

sinkhole - Sinkholes occur when earth on the surface collapses into a subterranean cavity that has formed in a limestone bed.

sludge - A semi-solid residue from any of a number of air or water treatment processes.

solvent - Substances (usually liquid) capable of dissolving or dispersing one or more other substances.

spoils - Dirt or rock that has been removed from its original location, destroying the composition of the soil in the process, as with strip-mining or dredging.

spring - An area where groundwater flows naturally onto the land surface.

stormwater - Water that is generated by rainfall and is often routed into drain systems in urban areas to prevent flooding.

stream - Any body of running water moving under gravity flow through clearly defined natural channels to progressively lower levels.

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

surface water - All water naturally open to the atmosphere (rivers, lakes, reservoirs, streams, impoundments, seas, estuaries, etc.); also refers to springs, wells, or other collectors which are directly influenced by surface water.

suspended solids (SS) - Defined in waste management, these are small particles of solid pollutants that resist separation by conventional methods. SS (along with BOD) is a measurement of water quality and an indicator of treatment plant efficiency.

sustainable development - Development that ensures that the use of resources and the environment today does not restrict their use by future generations.

swamp - A type of wetland that is dominated by woody vegetation and does not accumulate appreciable peat deposits. Swamps may be fresh or salt water and tidal or non-tidal.

T

tannic acid - One of many naturally occurring organic acids, tannic acid leaches from leaves and other organic material, giving water a tea or coffee color. The water is not polluted but in its natural condition; it has a low pH.

Tertiary treatment - Advanced cleaning of wastewater that goes beyond the secondary or biological stage. It removes nutrients such as phosphorus and nitrogen and most suspended solids. Membrane technologies such as reverse osmosis are tertiary treatment processes.

thermal pollution - The discharge of heated water from industrial processes into surface waters; it can alter habitats and affect aquatic plants and animals.

tidal marsh - Low, flat, coastal marshlands traversed by channels and tidal hollows and subject to tidal inundation. Normally, the only vegetation present is salt tolerant.

toxic - Harmful to living organisms.

transpiration - The process by which water absorbed by plants, usually through the roots, is evaporated into the atmosphere from the plant surface, principally from the leaves.

tributary - A stream or river that flows into a larger stream or river.

trophic state - The measure of a lake's fertility resulting from the quantities of the nutrients nitrogen and phosphorus in its water.

turbidity - Cloudiness caused by the presence of suspended solids in water; an indicator of water quality.

U

Unconfined aquifer - A permeable geologic bed, only partially filled with water, that overlies a relatively impervious underground layer.

underground storage tank - A tank located all or partially underground that is designed to hold gasoline or other petroleum products or chemical solutions.

United States Environmental Protection Agency (EPA) - Created in 1970 to facilitate effective governmental coordination of actions that occur on behalf of the environment. The agency's mission is to safeguard the health and welfare of the American people by protecting the environment and improving environmental quality. EPA is responsible for implementing most of the federal laws relating to protection of water and air quality.

United States Fish and Wildlife Service (USFWS) - An agency of the U.S. Department of Interior whose mission is to conserve, protect, and enhance the nation's fish and wildlife and their habitats for the continuing benefit of the American people. The agency is responsible for migratory birds, endangered species, certain marine mammals, inland sports fisheries, and specific fishery and wildlife research activities.

United States Geological Survey (USGS) - An agency of the U.S. Department of Interior that operates hydrologic data networks and conducts a variety of water-resources studies to support the resource assessment, evaluation, planning, conservation, and protection programs of federal, state and local agencies.

unsaturated zone - The area between the land surface and the water table where the soil is not fully saturated with water, although some water may be present.

urban runoff - Storm water from city streets and adjacent domestic or commercial properties that may carry pollutants of various kinds into the sewer systems and/or receiving waters.

V

W

waste disposal system - A system for the disposing of wastes, either by surface or underground methods; includes sewer systems, treatment works, and disposal wells.

wastewater - Water that carries wastes from homes, businesses, and industries; a mixture of water and dissolved or suspended solids.

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

water (H2O) - An odorless, tasteless, colorless liquid formed by a combination of hydrogen and oxygen; forms streams, lakes, and seas, and is a major constituent of all living matter.

water column - The depth from the water's surface to submerged bottom land.

water conservation - The care, preservation, protection and wise use of water.

water contamination - Impairment of water quality to a degree which reduces the usability of the water for ordinary purposes, or which creates a hazard to public health through poisoning or spread of diseases.

water management - The study, planning, monitoring and application of quantitative and qualitative control and development techniques for long-term, multiple use of the diverse forms of water resources.

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

water quality guidelines - Specific levels of water quality which, if reached, are expected to render a body of water suitable for its designated use. The criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.

water supply system - The collection, treatment, storage, and distribution of potable water from source to consumer.

water table - The top of the zone of saturation.

watershed - A geographic area in which water, sediment, and dissolved materials drain to a common outlet such as a point on a larger stream, a lake, an underlying aquifer, an estuary, or an ocean.

well - A pit, hole, or shaft sunk into the earth to tap an underground source of water.

wet deposition - See acid rain.

wetlands - Lands where water saturation is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the surrounding environment.

withdrawal use - The act of removing water from surface or groundwater sources in order to use it.

Z

zone of saturation - A subsurface zone in which all the pores or the material are filled with groundwater under pressure greater than atmospheric pressure.

zooplankton - Tiny aquatic animals of many species that form the base of the ocean food chain because they provide an important source of food for larger aquatic animals.