WATER TERMS

Acre-foot (a.f.) - The amount of water needed to cover an acre of land one foot deep, equal to 325,851 gallons.
Algae - Aquatic one- or multi-celled plants without true stems, roots and leaves but containing chlorophyll. Algae may produce taste and odor problems.
Alluvium - Debris from erosion, consisting of some mixture of clay particles, sand, pebbles, and larger rocks. Usually a good porous storage medium for groundwater.
Artesian well - A well in which water rises to the surface without pumping from a permeable geological formation that is overlain by an impermeable formation. No artesian wells remain in the Tucson area.
Artificial recharge - The deliberate act of adding water to a groundwater aquifer by means of a recharge project. Artificial recharge can be accomplished via injection wells, spreading basins, or in-stream projects. See also incidental recharge, natural recharge, recharge.
Aquifer - One or more geologic formations containing enough saturated porous and permeable material to transmit water at a rate sufficient to feed a spring or for economic extraction by a well. Combination of two Latin words, aqua or water, and ferre, to bring; literally, something that brings water.
Assured Water Supply - A technical term used in the Groundwater Management Act defined as a supply of water theoretically sufficient to meet the needs of a new development or customers of a municipal water supplier for 100 years. The methods for determining this are spelled out in AACR12-15-701.
Augmentation - Supplementing the water supply by such means as importing water from another basin or storing water.
Base flow - Streamflow derived from groundwater seepage into the stream; water that flows on the surface independent of precipitation.
Basin - See Groundwater basin.
Ccf (hundred cubic feet) - a unit of water used by some municipal water providers for metering and billing purposes. 1 Ccf = 748 gallons.
Central Arizona Project (CAP) - A facility consisting of canals, pumping stations and pipelines used to transport water from the Colorado River at Lake Havasu to Central Arizona and ultimately to Tucson.
CERCLA - The Comprehensive Environmental Response, Compensation and Liability Act, commonly known as Superfund, which regulates disposal and cleanup of hazardous materials.
Chloramine - A chemical used to disinfect and innoculate water supplies. Formed by combining chlorine and ammonia, chloramine is generally more stable but less potent than chlorine.
Chlorine - A chemical commonly used to disinfect water. It is highly effective against algae, bacteria and viruses, but not protozoa.
Coliform bacteria - a common type of bacteria found in soil and water and which grows in the intestines of warm-blooded animals. They are generally not harmful, but high levels may indicate the presence of other harmful bacteria or viruses.
Cone of depression - A drop in the water table around a well or wells which have been pumping groundwater. Depending on the rate of pumping and aquifer characteristics a cone of depression can be shallow and extend only a few feet or it can extent for several miles. Since water flows downhill underground, a cone of depression pulls water from the surrounding area into it, thus affecting the nearby water table.
Constructed wetland - A manmade wetland, usually designed to utilize wastewater and often involving a wildlife habitat component.
Consumptive use - A use that makes water unavailable for other uses, usually by permanently removing it from local surface or groundwater storage as the result of evaporation and/or transpiration. Does not include evaporative losses from bodies of water. Compare with non-consumptive use.
Corrosivity - A measure of the ability of water to corrode pipes. Corrosion occurs when metal is exposed to conditions which cause the breakdown of the metal through an exchange of ions. If corrosion is severe enough, the pipes may break entirely. EPA has no standards for corrosivity.
Desalinization - A process of removing salts and other dissolved minerals from water.
Disinfection byproducts - Compounds formed from the interaction of treatment chemicals with materials (usually organic) in the water.
Distribution system - An interconnected grid of water mains, valves, storage reservoirs and pressure boosting or reducing facilities.
Downgradient - The direction water flows by force of gravity.
Drawdown - A lowering of the groundwater level or the piezometric pressure caused by pumping, measured as the difference between the original groundwater level and the level after a period of pumping.
Effluent - Water that has been collected in a sewer for subsequent treatment (ADWR definition). The term is also commonly used to refer to water discharged from a treatment plant.
Evapotranspiration - The amount of water transpired through pores and evaporated by vegetation.
Electrodialysis - a membrane filtration process that uses an electric charge rather than water pressure to force dissolved solids through the membrane pores. Used by Buckeye, AZ.
Filtration - The process of passing water through materials with very small holes (pores) to strain out particles. Filtration can remove microorganisms including algae, bacteria and protozoa, but not viruses.
Flexibility Account - A paper account in which farmers can accumulate credits for unused portions of their groundwater allotments for use in meeting conservation requirements in the future.
Floodplain - The area near a watercourse inundated during floods. The 100-year floodplain is the area that is expected to be inundated by a flood of a magnitude that has a one-in-a-hundred probability of occurrig in any year.
GPCD (Gallons per capita per day) - The amount of water used on average by an individual each day. Total gpcd is calculated by dividing total water use in the area, including industrial and commercial uses, by the number of users. Residential gpcd is the number resulting from only considering domestic water use.
Gradient, hydraulic - The change of pressure per unit distance from one point to another in an aquifer. When an area is said to be “downgradient” it is at a lower level and water will flow in that direction.
Groundwater - Subsurface water body in the zone of saturation, or more commonly, available groundwater is defined as: That portion of the water beneath the surface of the earth that can be collected with wells, tunnels, or drainage galleries, or that flows naturally to the earth’s surface via seeps or springs.
Groundwater basin - An area enclosing a relatively distinct hydrologic body or related bodies of groundwater.
Groundwater savings facility (GSF) - A facility, usually a farm, which agrees to use a renewable water supply such as CAP water instead of groundwater under the UWS program. Entities with extra renewable supplies, such as municipal water providers, sell CAP water to the farms and in return get a credit for groundwater saved, which can be used to offset future groundwater pumping.