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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #
Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link.
- A -
AWWA
American Water Works Association. The drinking water industry's trade association.
Acre Foot
A volume of water equal to one foot in depth covering an area of one acre, or 43,560 cubic feet; approximately 325,851 gallons. Roughly two-thirds of an acre foot serves the needs of a typical family for a year.
Alluvial Water
Ground water that is hydrologically part of a surface waterway.
Appropriation
Appropriate (verb) To take the legal actions necessary to create a right to take water from a natural stream or aquifer for application to beneficial use.
The right to take water from a natural stream or aquifer for beneficial use at a specified rate of flow for immediate use, or to store such water for later use. Usually evidenced by a water court decree.
Aquifer
An underground layer of sand, gravel or rock through which water can pass and is stored. Aquifers supply the water for wells and springs.
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- B -
Backflow Prevention
Prevention of the flow of any foreign liquids, gases or substances into the distribution pipelines of a potable water supply.
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- C -
Clean Water Act
The law that sets forth how the United States will restore and maintain the chemical, physical and biological integrity of the country's waters (oceans, lakes, streams and rivers, ground water and wetlands). The law provides protection to the country's waters from both point and nonpoint sources of pollution.
Coliform
A bacteria that originates in the digestive system of mammals. If found in water, it alerts lab technicians to potential problems.
Conjunctive Use
Coordinated use of surface and ground water supplies to meet demand so that both sources are used more efficiently.
Conservation
Obtaining the benefits of water more efficiently, resulting in reduced demand for water. Sometimes called end-use efficiency or demand management.
Cubic Feet Per Second (CFS)
A rate of flow of water passing a given point, amounting to a volume of one cubic foot for each second of time. Equal to 7.48 gallons per second, 448.8 gallons per minute, or 1.984 acre feet per day.
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- D -
Diversion
The removal of water from its natural course or location, or controlling water in its natural course or location, by means of a ditch, canal, flume, reservoir, bypass, pipeline, conduit, well, pump or other device.
Drought
A long period of below-average precipitation.
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- E -
Endangered Species Act
The law that sets forth how the United States will protect and recover animal and plant species whose populations are dangerously in decline, or close to extinction. The law protects not only threatened and endangered habitat but also the ecosystems upon which species depend.
Environmental Impact Statement (EIS)
A detailed analysis of the impacts of a construction project on all aspects of the natural environment required by federal law for federal permitting or use of federal funds.
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- F -
Federal Land Policy Management Act (FLPMA)
A Federal law that requires land use planning and management programs, along with land acquisition and disposition on national forest systems, including lands with the Department of Interior and the Department of Agriculture. The Act requires the lands be managed in a manner to protect the quality of scientific, scenic, historical, ecological, environmental, water resource and archaeological values.
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- G -
Ground Water
Water found below the surface of the Earth.
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- H -
Hydrologic Cycle
The movement of water from the atmosphere to the Earth and back again to the atmosphere. The three stages are precipitation, runoff or infiltration, and evaporation.
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- I -
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- M -
mg/L
Milligrams per liter; a measurement describing the amount of a substance (such as a mineral, chemical or contaminant) in a liter of water. One milligram per liter is equal to one part per million.
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- N -
National Pollution Discharge Elimination System (NPDES) Permit
A permit required under Section 401 of the Clean Water Act regulating discharge of pollutants to the nations water. National Environmental Policy Act (NEPA)
The federal law enacted to ensure the integration of natural and social sciences and environmental design in planning and in decision making that may impact the quality of the human environment.
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Parts Per Billion
A unit frequently used to measure contamination concentration (parts of contamination per billion parts of water). One thousand parts per billion is equal to one part per million.
Parts Per Million
A unit used to measure contamination concentration (parts of contamination per million parts of water). One part per million is equal to one milligram per liter. (This term is becoming obsolete as instruments measure smaller particles.)
Potable
Water that does not contain pollution, contamination, objectionable minerals and is considered safe for domestic consumption; drinkable.
Pressure Regulating Valve (PRV)
A device that takes pressure from a high zone through a valve and regulates it to a zone of lower pressure.
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- R -
Raw Water
Untreated water
Reservoir
A body of water used to collect and store water, or a tank or cistern used to store potable water.
Reverse Osmosis
A water treatment technique that forces water through a dense membrane to remove impurities.
Runoff
Water that flows on the surface of the Earth into streams, rivers, lakes and oceans.
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- S -
Safe Drinking Water Act (SDWA)
Federal legislation passed in 1974 that regulates the treatment of water for human consumption and requires testing for and elimination of contaminants that might be present in the water.
Surface Water
Water located on the Earth's surface.
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- T -
Tap
A physical connection made to a public water distribution system that provides service to an individual customer.
Treated Water
Water that has been filtered and disinfected. Term is sometimes used interchangeably with potable water.
Tributary
A stream or river that flows into a larger one.
Tributary Drainage
The area from which water drains by gravity into a water course.
Tributary Ground Water
Water below the Earth's surface that is physically or hydrologically connected to natural stream water so as to affect its flow whether in movement to or from that stream.
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- U -
Unaccounted-For Water
The difference between the total amount of water leaving treatment facilities and the total amount of water measured at customer's meters. Besides system losses, it also includes beneficial uses such as fire fighting and water used in system maintenance, along with meter under-registration.
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- W -
Water Right
A property right to make beneficial use of a particular amount of water.
Watershed
An area from which water drains and contributes to a given point on a stream or river.
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- X -
Xeriscape
A landscape concept to describe landscaping that requires less water. The term was developed by Denver Water in 1981. It is derived from the Greek word Xeros, meaning dry.
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- # -
µg/L (micrograms per liter)
Micrograms per liter; a measurement describing the amount of a substance (such as a mineral, chemical or contaminant) in a liter of water. It is expressed in terms of weight per volume. One µg/L is equal to one part per billion.
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Revised: July 22, 1998
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