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acid mine drainage - Low pH drainage water from certain mines usually caused by the oxidation of sulphides to sulphuric acid. Mine drainage can also contain high concentration of metal ions.

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

activated alumina - Strongly basic ion exchange media used to remove contaminants such as arsenic and fluoride. Often manufactured from a natural aluminum based mineral called gibbsite. When used in a filter or contactor, it needs periodic regeneration like a water softener.

activated carbon - An adsorbent material used to remove mostly taste and odour causing materials, pesticides and other similar compounds. After it's been used, activated carbon is either replaced or regenerated. Regeneration of activated carbon is not feasible for small water systems. Activated carbon comes in a granular form which is used in filters and a powdered form which is mixed with water and then removed.

acute health effect - An immediate (within hours or days) effect that may result from exposure to certain drinking water contaminants.

aeration - Process of blowing air (or another gas such as carbon dioxide) through a liquid or solid.

aerobic - Any biological process that occurs int he presence of oxygen; also applies to organisms that require oxygen to survive.

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.

alkalinity - A measure of water's acid-neutralizing capacity and is primarily a function of carbonate, bicarbonate and hydroxide.

aluminum - Varying amounts of aluminum are present naturally in groundwater and surface water supplies.

ambient - The surrounding environment.

anaerobic - Any process that can occur without oxygen; also applies to organisms that can survive without oxygen.

anion exchange - Type of ion exchange process where a resin is used to exchange a negatively charged ion from the media with another negatively charged ion that is less desirable. The resin used needs regular regeneration.

anthropogenic - Resulting from the influence of humans; induced or altered by human presence or activities.

aquaculture - The managed production of fish under controlled conditions.

aquatic - Term used to describe any organism growing in. living in, or frequenting water; some plants and animals that live in water are called aquatic species.

aquatic ecosystem - Basic ecological unit composed of living and nonliving elements interacting in an aqueous environment.

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).

aquitard - Geological formation of a semi-impermeable and semi-confining nature, which transmits water at a very slow rate. It serves mostly as a storage unit for groundwater rather than yield water to springs or wells.

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

arsenic - This metal occurs naturally in some groundwater supplies and is classified as a carcinogenic to humans.

artesian well - A well in which water from a confined aquifer rises above the water table of the aquifer.

assimilative capacity - Amount of pollutants that a water body may absorb while continuing to meet water quality standards.

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).


bacteria - Simple, unicellular organisms with an average size of 1/1,000 mm diameter.

Best Management Practices - Management or construction practices designed to be effective and reduce the impact on the environment.

bicarbonate - The major form of alkalinity. In excessive amounts, in conjunction with calcium, may cause scale formation in water heaters.

bioaccumulation (bioconcentration) - Occurs when plants or animals collect contaminants in their tissues over time; when low amounts of contaminants are continually absorbed, they build up and can cause illness.

biochemical oxygen demand (BOD) - A laboratory test to measure the amount of oxygen consumed by microorganisms as they decompose organic matter; the test indicates the amount of organic material in a water sample.

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

bioindicators - Organisms that are used to detect changes in environmental pollutant levels, such organisms are usually sensitive to changes in their surroundings.

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

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

bioremediation - Process to reduce contaminant levels in soil or water by using microorganisms or vegetation

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

BOD - See biochemical oxygen demand.

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

boron - Occurs naturally in over 80 minerals.  The most common form of boron in drinking water is boric acid and it's usually found in higher concentrations in groundwater than surface water.

boundary water - A river or lake that is part of the boundary between two or more countries or provinces that have rights to the water.

buffering capacity - Ability of a substance to resist an increase or decrease in pH.

by-product - New products or substances formed when a chemical reaction occurs. Substances formed when making something else.


cadmium - A small percentage is derived from drinking water.  It can be present as an impurity in galvanized pipes, solders used in fitting water heaters and coolers, or polyethylene pipes, and, as such, may contaminate water supplies through distribution.

calcium - An abundant natural element that enters the water system through weathering of rocks (especially limestone) and from the soil through seepage and runoff.  Groundwater generally contains a higher concentration than surface water and when treated with lime will be even greater.

carcinogen - A chemical substance or type of radiation that can cause cancer in exposed animals or humans.

cartridge filter (1 micron absolute) - Uses a cylinder of material (usually pleated) through which a solution passes leaving the contaminants on one side of the material and cleaner water on the other.  Cartridge filters come with many different pore sizes; larger pore size allows larger contaminants through the material. A pore size of 1 micron will not allow most protozoa to pass through although viruses and bacteria will pass through the material.

catchment - A surface from which draining water is collected.

cation exchange - Type of ion exchange process where a resin is used to exchange a positively charged ion (commonly sodium) from the media with another positively charge ion that is less desirable, such as those that cause hardness (commonly used in water softeners). The resin used needs regular regeneration.

channelization - The straightening or dredging of a stream to make it straighter, deeper or shorter.

chloramines - Chemical compounds containing chlorine and nitrogen used in disinfection of drinking water.

chloride - Charged Anion formed from chlorine.  In water supplies, it imparts an undesirable taste to water and beverages prepared from water.

chlorination - Process of purifying/disinfecting water by adding chlorine.

chlorine - An oxidizing agent commonly used as a disinfectant. When added to water, it reacts to form two disinfectants know as "free residual chlorine" and "total residual chlorine". It is an oxidant and is very effective in destroying bacteria and viruses.

chlorine dioxide - A powerful oxidant used in disinfection but it is more difficult to handle than other forms of chlorine. It must be generated on-site and requires trained staff to manage it.

chlorine residual - The amount of total chlorine maintained in treated drinking water as it travels through a distribution system. It can be free chlorine, combined chlorine (chloramines) or a combination of both.

chlorine, combined - A measurement of the amount of chloramines produces as a result of the reaction of chlorine with ammonia present in water.

chlorine, free - A measurement of the amount of the chlorine available after a portion has been used up in reactions with the substances present in water.

chlorine, total - A measurement of both free and combined chlorine.

chromium - Trivalent chromium, the most common natural state, is not considered to be toxic. However if present in raw water, it may be oxidixed to hexavalent chromium during chlorination (toxic effects in humans attributed primarily to hexavalent form). The main toxic effects observed in animals are on the liver, kidney and gastrointestinal tract.

cistern - A water storage tank typically used for catching and storing rainwater.

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.

coagulation - Water treatment process in which chemicals are added to water that enables them to become attached to each other.

coliform bacteria - Naturally occurring bacteria used as an indicator of whether water is safe for human consumption. Most coliform bacteria are harmless but their presence indirectly suggests disease-causing bacteria could also be present.

coliform bacteria, fecal - A group of coliform bacteria found in the intestines of warm-blooded animals and humans and are shed in feces.  Fecal coliform bacteria in water indicates the presence of pollution. The most widely publicized of the fecal coliform group is the species called Escherichia Coli or E. Coli. which is extremely harmful to humans if ingested.

coliform bacteria, total - A measure of the amount of coliform bacteria found in a water sample and is used as an indicator that contamination may have occurred or that water treatment processes are not working properly. This triggers a repeat of the treatment process.

colour - Is most often caused by either dissolved organic matter or dissolved metals like iron or manganese.

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

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

conductivity - The property of a body to conduct electricity.

confluent growth - Term used to describe when the general bacteria population found in a water sample is so excessive it prevents the detection of any harmful bacteria. Re-sampling is always necessary.

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 humans, 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.

copper - Copper and its compounds are widely distributed in nature and frequently found in surface water and in some groundwater. When copper piping is used in the distribution system, water will contain more copper than the original water supply.

corrosive water - Water that reacts with and dissolves metal surfaces and materials; determined by the type of rocks, soil and other materials that water comes into contact with and can be the result of natural or man-made influences. Water's corrosive properties are related to various water quality factors such as temperature, total dissolved solids, calcium hardness, alkalinity and pH. Primary health concern related to corrosive water is that metals present in pipes and plumbing items may be released into the drinking water.

coulee - A dry or intermittent stream valley, especially a long trench-like gorge that once carried meltwater from an ice sheet.

Cryptosporidium - Common intestinal parasite (protozoa) commonly found in lakes and rivers, which is highly resistant to disinfection. May cause gastrointestinal illness.

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

cumulative effects - Combined environmental impacts that accumulate over time and space as a result of a series of similar or related individual actions, contaminants or projects.

cyanide - An extremely toxic and fast acting poison.  However, because it can be detoxified to a certain extent in the human body, cyanide poisoning generally results from acute exposure to high doses, not from chronic ingestion of low doses.


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.

dilution - To decrease the concentration of a substance by mixing it with another or by adding water.

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, streamflow, and yield.

disinfection - A chemical or physical process that kills microorganisms.

disinfection by-products - Chemical compounds formed when chlorine reacts with natural organic matter in water.

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 limit its use in industrial processes.

distillation - Producing clean water by boiling water that produces stream. The stream condenses to pure water and most pollutants and contaminants remain in the original liquid.

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.

drainage basin - See: Watershed.

dredgeate - The material excavated from lake, river, or channel bottoms during dredging.

dredging - The removal of material 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 sulphur and nitrogen oxides that, 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. coli (Escherichia coli) - Type of fecal coliform bacteria. A particular strain, called E. Coli 0157:H7, has been found to be extremely harmful to humans if ingested. It produces a protein toxin that causes severe damage to the intestinal cells of infected individuals.

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

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

electrodialysis - Uses an electric voltage to cause charged particles to be removed from a solution.  Only pure water and electrically neutral substances remain in the finished water.

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

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

Environmental Impact Statement (EIS) - A report submitted by a company to describe a project or development, the possible positive or negative impacts of its actions, and its plans to reduce, mitigate or avoid these impacts; the information in the report is based on studies that have been carried out. The report is reviewed by the appropriate government agencies and the public.

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

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 nearshore ocean waters, where tidal action and river flow create a mixing of fresh water and saltwater. These areas may include bays, mouths of rivers, salt marshes, and lagoons. These brackish water ecosystems shelter and feed marine life, birds, and wildlife.

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 vapour.

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


fecal coliform - Bacteria that come from the intestinal tracts of mammals and are released in faeces.

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.

filtration - Process of separating liquids from solids by passing the liquids through a porous barrier (filter).

finished water - Water that has been treated and is ready to be delivered to consumers.

flocculation - A coming together of particles in water to form larger particles that is easier to remove.>

flocculent - Chemical added to water that attaches to small particles and helps them sink; the material that settles on the bottom can be removed to improve the clarity of the water.

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; the comparative change in market or sales value; or 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 portion of the floodplain where water depths are shallow and velocities are low.

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 low land adjacent to a stream or lake.

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

floodway - The channel of a river or stream and those parts of the adjacent floodplain adjoining the channel that 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.

fluoride - Charged Anion species derived from fluorine. Occurs naturally in minerals and soils. The fluoride concentration in natural waters varies widely.

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 litre of dissolved solids such as salts, metals, nutrients, etc.


GAC - Granular activated carbon; see activated carbon.

Giardia - A protozoa (parasite) frequently found in rivers and lakes, which, if not treated properly, may cause gastrointestinal illness.

glacier - A huge mass of ice, formed on land by the compaction and re-crystallization of snow, that moves very slowly downslope 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.

greywater - Liquid wastes from showers, baths, sinks, kitchens and domestic washing facilities; does not include toilet wastes.

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

groundwater recharge - The inflow to an aquifer.

groundwater under the influence (GUDI) - GUDI of surface water is groundwater that is found below surface of the ground and is in contact with surface water. It may also be referred to as 'groundwater under the direct influence of surface water (GWUDI)'.


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

hardness, total - Caused mainly by the presence of calcium and magnesium. Scale formation and excessive soap consumption are the main concerns. When heated hard waters have a tendency to form scale deposits which shorten the life of water heaters and other appliances.

hazardous waste - This type of waste includes toxic flammable, corrosive and oxidizing substances and is subject to special handling, shipping, storage and disposal requirements; waste that poses a risk to human health or the environment.

herbicide - Substances used to kill unwanted plants which compete with a crop for sunlight, nutrients and water.

heterotrophic plate count (HPC) - Measure of the total number of bacteria of all types present int he water. Large concentrations of a general bacterial population can hinder the detection of E. coli bacteria.

human consumptive use - Water that can be used for drinking, cooking, food preparation and oral hygiene whether or not it was intended for those uses.

hydrocarbons - Any substance containing carbon and hydrogen in various combinations (e.g., gasoline and oil).

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

hydrogeology - Study of groundwater, with particular emphasis on the chemistry and movement of water.

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.

hygienic water use - Water to be used for bathing, personal hygiene and showering or less critical water uses. Cannot be used for human consumptive use.


impoundment - Structure of location used for confined storage, such as a pond, lake or reservoir.

impurity - Unwanted chemical substance that is present within another substance or mixture.

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 rainwater into a sewer system from sources other than infiltration, such as basement drains, sewer holes, storm drains, and street washing.

inorganic - Matter other than plant or animal and not containing a combination of carbon, hydrogen, and 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.

intermittent stream - Watercourse that does not flow continuously, or flows during spring and summer only.

inorganic contaminants - Mineral-based compounds such as metals, nitrates and arsenic that are naturally occurring in water or have been introduced through human activities such as farming and manufacturing.

iron - When iron precipitates, it will add a reddish-brown colour to the water. Water high in iron favours the growth of iron bacteria, a slime forming organism that causes clogging of pipes as well as a foul taste and odour.

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


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.


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.

leachate - Water or other liquid that has washed (leached) from a solid material, such as a layer of soil or waste; leachate may contain contaminants.

leaching - Occurs when a liquid (e.g., water) passes through a substance, picking up some of the material and carrying it to other places; this can happen under ground in solid rock, or above ground through piles of material.

lead - It is present in tap water as a result of either natural sources or from household plumbing systems (e.g., lead pipes, solder). As lead is a component of many plumbing systems, it is also recommended that only the cold water supply be used for drinking and cooking in order to minimize exposure of lead introduced into drinking water.

licensee - The individual or organization to whom a licence is issued or assigned.

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


magnesium - Present in all natural waters; a major contributor to water hardness and may also contribute to undesirable tastes in drinking water. When present in water with sulphate, magnesium may have a laxative effect or cause gastrointestinal irritation.

manganese - Seldom found alone in a water supply and is usually accompanied by iron. Manganese salts and minerals are widely distributed in rocks, soils and sediments. Manganese can cause water to have an objectionable taste or odour and produces dark brown or black stains to plumbing fixtures and laundry. The presence of manganese in water may lead to the accumulation of microbial growths in the distribution system. Dissolved manganese oxidizes more slowly than iron and is more difficult to remove from water.

Maximum Acceptable Concentrations (MACs) - Established by Health Canada for substances that are known or suspected to cause adverse effects on human health. MACs are determined based on the assumption that lifelong exposure to drinking water containing the substance, at that concentration, may cause adverse health-related problems.

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

megawatt - A unit of electricity equivalent to 1000 kilowatts.

mercury - The presence of mercury in water is a concern as organic mercury can bio-accumulate in fish and other aquatic life.

mg/L - See milligrams per litre.

micrograms per litre (ug/L) - 1 ug/L equals 0.001 mg/L (equivalent to 1 teaspoon in 1,300,000 gallons of water).

micron - 39.37 millionths of an inch, or 0.001 millimetre.

microorganisms - Living organisms that can be seen only with the aid of a microscope.

milligrams per litre (mg/L) - most common type of unit used when dealing with the concentration of various substances in water (1 mg/L is roughly equivalent to 1 teaspoon in 1,300 gallons of water).

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

mollusc - Member of a diverse group of invertebrates, including snails and clams, which are mostly aquatic and covered with an external calcium carbonate shell.


NAPLs - Nonaqueous phase liquids; i.e., chemical solvents such as trichloroethylene (TCE) or carbon tetrachloride - often toxic. Many of the most problematic NAPLs are DNAPLs - dense nonaqueous phase liquids.

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

Nephelometric Turbidity Unit(NTU) - A measure of turbidity; an optical parameter based on the amount of light reflected from a water sample. Water with more particles (e.g., organics, particulates, organisms) will have a higher turbidity. The change of turbidity in water as it is treated is oten used as a measure of treatment effectiveness.

nitrate - Sources of nitrate in water (particularly groundwater) include decaying plant or animal material, agricultural fertilizers, manure or domestic waste. As nitrates are very soluble and, therefore, highly mobile in soil, they can readily migrate to the water table.

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, and metal ores.

NTU - See Nephelometric Turbidity Unit.

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).


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.

owner/operator - The organization or person(s) who own or run the drinking water system (including treatment plant(s) and distribution system).  Examples include public or private water utilities.

ozonation - Ozone is a highly reactive and smelly gas formed from oxygen. When added to water, it can kill bacteria and pathogens.


PAC - Powdered activated carbon; see activated carbon.

parameter - Refers to a measurable or quantifiable item that is being tested.

parts per billion (PPB) - 1 ppb is equivalent to 1 ug/L when discussing concentrations of substances in water.

parts per million (PPM) - This unit is commonly used to represent pollutant concentrations; large concentrations are expressed in percentages; 1 ppm is equivalent to one milligram per litre.

pathogen - A disease-inducing organism or abiotic (non-living) agent. Can cause gastrointestinal illness in humans when ingested. These illnesses are usually non-life threatening but can be very serious in small children, the elderly or immuno-compromised individuals.

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

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

permafrost - Perennially frozen layer in the soil, found in alpine, arctic, and antarctic regions.

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 - A measure of the hydrogen ion concentration in water and determines whether water is acid or alkaline on a scale of 0 to 14, with 7 representing neutrality. Numbers less than 7 indicate increasing acidity and numbers greater than 7 indicate increasing alkalinity.

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, (e.g., algae) sometimes consisting of only one cell.

plankton - Tiny plants and animals that live in water.

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

point source - A static, identifiable source of air, soil or water pollution.

pollutant - Contaminant that negatively impacts the physical, chemical or biological properties of the environment.

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

potable water - Water that is suitable and safe for human consumption.

potassium - An alkali metal that is rarely found at high levels in water supplies.

ppb - see parts per billion.

ppm - see parts per million.

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

private water system - Individual domestic drinking water system used for personal or family (i.e., farms, rural homes and acreages) needs only. Drinking water quality in these systems is not regulated.

public waterworks - Municipal water supplies (municipal waterworks and municipal wells connected to a distribution system), certain pipeline systems and other waterworks that are designed to supply more than 18 cubic metres (about 4,000 gallons) of water in a 24-hour period.

protozoa - Single-celled organisms.  More complex physiology than viruses and bacteria. Average size of 1/100 mm diameter.


radionuclides - Radioactive chemicals that are usually naturally occurring and may be found in drinking water. Typical radionuclides include radioactive isotopes of uranium, thorium, radium, lead and polonium.

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

raw water - Water in its natural state, prior to any treatment for drinking.

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.

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

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.

reverse osmosis - Process that forces a solution through a barrier that retains contaminants on one side and almost pure water on the other.

riparian - Pertaining to anything connected with, or immediately adjacent to, the banks of a lake, river or other body of water.

river - A natural stream of water of substantial volume.

river basin - A term used to designate the area drained by a river and its tributaries.

runoff - Water that is not absorbed by soil and drains off the land into bodies of water. Can be caused by either rain or melt water.


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

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

sediment - Solid material that settles from a liquid; e.g., mud will sink and settle at the bottom of a river or stream because it is heavier than water.

sedimentation - Removal of heavy settleable particles from water by allowing them to sink to the bottom of a basin by gravity.

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

selenium - Appears to be an essential element in human nutrition and food is the main source.

semi-public waterworks - Drinking water system with few source connections than regulated for a public system but more than for personal or family use.  (i.e. serving restaurants, motels, campgrounds, small parks, municipal wells with no distribution system and other small systems accessible to the public).  These systems deliver less than 18 cubic metres per day.

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 private sewage disposal system.

settling pond - Natural or artificial waterbody used to contain wastewater in order to enable solids to be removed from it before it is released to the natural environment.

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

sewage disposal - Area and structures designed to contain facilities and treat sewage.

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.

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.

shock chlorination - Refers to adding high chlorine levels to a well to kill or eliminate bacteriological growths that can cause illness or create aesthetic problems. (e.g., taste and odour). Disinfection is routinely used to control bacteria in wells and is applied as a part of start-up procedures for newly constructed wells and should be used as semi-annual maintenance for existing wells.  Disinfection should be performed in the event of contamination (e.g., flooding or unacceptable bacteriological results).

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

siltration - Deposition in a waterbody of sediments (e.g., sand and clay) that appear as tiny suspended particles.

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

sodium - Found in all natural water supplies and can be introduced into water supplies through the ion exchange water softening process. High concentrations tend to increase the corrosive effect of the water and can cause an unpleasant taste. For health reasons, sodium rich water should never be consumed.

solid waste disposal facilities - Area and associated structures designed to contain solid wastes.

solubility - Quantity of material that dissolves in a given volume of water.

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

source water - Water in its natural or raw state, prior to being withdrawn for treatment and distribution as a drinking water supply.

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.

storm sewer - A system of pipes (separate from sanitary sewers) that carry only water runoff from building and land surfaces.

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

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. The term "streamflow" is more general than the term "runoff", as streamflow may be applied to discharge whether or not it is affected by diversion or regulation.

sulphate - Occurs naturally in water. In concentrations in excess, especially if the magnesium content is also high, sulphate may have a laxative effect or cause gastrointestinal irritation.

sump - Excavation for the purpose of catching or storing liquids such as greywater; the water drains into the soil.

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 that 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. Suspended solids (along with biological oxygen demand) are 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 water or saltwater and tidal or nontidal.


temperature - The degree of hotness or coldness. Water temperature will affect the efficiency of water treatment processes.  Low temperature decreases efficiency of treatment processes and high temperatures enhance the growth of nuisance organisms. This makes it a crucial component of treatment design.

thermal pollution  - The impairment of water quality through temperature increase; usually occurs as a result of industrial cooling water discharges.

THMs - See trihalomethanes.

total dissolved solids - Indicates the concentration of ions in the water. High mineral content can restrict the use of the water, depending on the specific minerals present and their individual concentrations. Some of the properties of highly mineralized water can include excessive hardness, taste, mineral deposition and corrosion

total organic carbon – A laboratory measurement that indicates the amount of organic matter in water.

toxic - Harmful to living organisms.

transmissivity – A measure of the rate of movement of water through an aquifer.

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 that contributes its water to another stream or body of water.

trihalomethanes (THMs) - Formed in drinking water when chlorine reacts with organic material in water supplies. Chloroform is the most frequently detected THM in drinking water supplies.  Health Canada is currently assessing the health risks associated with THMs.

trophic - The nutrients status of a waterbody determined by the average concentration of total phosphorous and the algae growth (productivity) that the phosphorous can sustain.  The major trophic states are eutrophic (high), mesotrophic (medium) and oligotrophic (low).

tsunami  - A Japanese term that has been adopted to describe a large seismically generated sea wave capable of considerable destruction in certain coastal areas, especially where sub-marine earthquakes occur.

turbidity  - Cloudiness caused by the presence of suspended solids in water; an indicator of water quality.  High turbidity levels can interfere with drinking water treatment processes because the particulate matter in the water provides nutrients for pathogens that may be present, and it reduces the effectiveness of disinfectants in destroying them.  Particles, suspended in water or wastewater, that interfere with the passage of light; high turbidity makes water appear unclear or cloudy and is harmful to organisms such as fish.


ug/L - see micrograms per litre.

ultraviolet light - Invisible to the naked eye, it damages microorganisms and prevents them from reproducing and stops these microorganisms from causing sickness.

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

units - Most parameters are measured in milligrams per litre (mg/L), but some are measured in micrograms per litre (g/L). The unit measure of g/L is much smaller than milligrams per litre. Milligrams per litre refers to parts per million and micrograms per litre refers to parts per billion. The parameters you may see measured in micrograms per litre are arsenic, uranium, mercury and trihalomethanes.  To convert micrograms to milligrams, divide by 1000.  To convert milligrams to micrograms, multiply by 1000

upstream location - A location up-gradient of a wastewater release point beyond the influence of treated effluent.

- May enter water supplies from naturally occurring deposits or as a result of human activities (like the application of phosphate fertilizers). Nephritis is the chemically-induced effect of uranium in animals and humans.

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.


value - Measured or quantified result of a particular parameter.

vapour - The gaseous phase of substances that are liquid or solid at atmospheric temperature and pressure, e.g., steam.

vector - Any organism or abiotic force capable of transferring a pathogen from one organism to another.

virus – Very simple life forms that do not multiply outside of living host cells.  Average size of 1/10,000 mm diameter.



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 odourless, tasteless, colourless liquid formed by a combination of hydrogen and oxygen; forms streams, lakes, and seas, and is a major constituent of all living matter.

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

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

watershed - The land area of which rainfall (and/or snow melt) drains into a single point or stream.   Ridges of higher ground generally form the boundaries between watersheds.  At these boundaries, rain falling on one side flows towards the low point of one watershed, while rain falling on the other side flows towards the low point of a different watershed. 

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.

water use - Whenever water is used by an activity or organism, either in the place it is found or by withdrawing it.

weathering - The process by which particles, rocks and minerals are altered upon exposure to surface temperatures and pressure, air, water, wind and biological activity.

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

wellhead – The structure built over a well to maintain water protection.  The land area surrounding a drinking water well or well field.

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. Other common names for wetlands are bogs, ponds, estuaries, and marshes.

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


zinc- An essential element for human nutrition, with a daily requirement between 4 and 10 mg.  Long-term ingestion of zinc in amounts exceeding the daily requirement has not shown adverse effects. Water containing zinc at concentrations higher than 5 mg/L can have an undesirable “astringent” taste and may develop a greasy film on boiling.

zooplankton - Tiny aquatic animals eaten by fish.

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


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  • Durrenberger, Robert W. Dictionary of the Environmental Sciences. Palo Alta, Ca.: National Press Books, 1973.
  • Government of Canada. "Glossary of selected terms." The State of Canada's Environment. Ottawa, 1991.
  • North Dakota State Water Commission. Water words: a glossary of water-related terms. Bismark, 1988.
  • Parker, Sybil P. (Ed). McGraw-Hill Dictionary of Scientific and Technical Terms. 3rd ed. New York: McGraw-Hill, 1984.
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  • UNESCO; World Meteorological Organization. International Glossary of Hydrology. Geneva, Switzerland, 1974.
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