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SourcesGlossaryAcidity: The total amount of acid and acid forming substances in water. See also pH. ADEQ: Arizona Department of Environmental Quality. Administers all of Arizona’s EPA programs and regulates community water systems that have at least 15 service connections or serve 25 people. ADWR: Arizona Department of Water Resources. Established five Active Management Areas (AMAs) to manage and balance the availability of ground water resources until 2025. Aeration: Water treatment process that uses forced air to remove volatile contaminants from water. Alkalinity: Total amount of bicarbonate and carbonate ions present in water reported in mg/L of calcium carbonate. Water alkalinity helps protect (buffers) against abrupt pH changes limiting its range to between 7.5 and 8.5. Alkalinity and hardness also control pipe scale formation. There is no drinking water standard for alkalinity. Alluvial: A general term for sedimentary deposits made by streams on river beds, flood plains, and alluvial fans, especially a deposit in an arid or semiarid region where a stream issues from a canyon unto a plain or valley floor. AMAs: Active Management Areas. Set by ADWR to manage and balance groundwater resources in Arizona. Anions: Negatively charged ions. Examples: chloride and sulfate. Aquifers: are bodies of geologic material that is sufficiently permeable to conduct ground water and to yield economically significant quantities of water to wells. Artesian: Pertaining to ground water under sufficient hydrostatic pressure to rise above the aquifer containing it. Atrazine: An s-triazine-ring herbicide that is used globally to stop pre- and post-emergence broadleaf and grassy weeds in major crops. Basalt: A dark-colored consolidated igneous rock, commonly extruded from volcanoes. Base flow: The level at which the water in a river is sustained by ground water, not including overland surface water flow contribution. Benzene: A volatile organic chemical used as an industrial solvent and a major component of gasoline. Biofilm: A structured community of microorganisms encapsulated within a self -developed matrix and adherent to a living or inert surface. Calcite: A very common mineral composed of calcium and carbonate ions. Chloramine chemicals: Chlorine- and ammonia-based chemicals used for long-term residual disinfection of potable water. Chloramines are very effective at controlling bacterial and algal growth in water; however, they are also very toxic to fish. Coliform bacteria: Routine water testing for coliform bacteria is used as an indicator of animal or human fecal contamination. Positive results may indicate the presence of pathogens such as bacteria, viruses, and parasites (present in surface water only) in the water. Consolidated and unconsolidated: Terms to describe geologic material. A consolidated rock has undergone any process whereby loose, soft, or liquid earth materials become firm and coherent, for example the cooling of lava or the cementation of sand. An unconsolidated material typically consists of sediment (sand, gravel, silts and/or clays) that is loosely arranged or whose particles are not cemented together. Contact time: In chlorination, the period of time between the introduction of chlorine to the water and when the water is safe to drink (the time needed to effectively disinfect the water). Contaminants: Foreign substances (such as chemical, microbe, or plant and/or mineral particulate matter) found in water. Contaminants may or may not be harmful to human health. Corrosion: In metal pipelines, corrosion occurs spontaneously by the presence of oxygen in water. Pipe corrosion is accelerated by corrosive water, high TDS, low (acidic) pH, low alkalinity, and high concentrations of chloride and sulfide ions. Iron metal pipes corrode the most, followed by zinc (galvanized ion) and copper metal pipes. Modern plastic pipes used in home construction do not corrode. Disinfection by-products: Organic chemicals such as chloroform that can form during water disinfection using chlorine-based chemicals. Their concentrations are regulated under the NPDWS. Dolomite: A common mineral composed of calcium, magnesium, and carbonate ions. Down Gradient: Down stream or down hill. Ground water flows in the aquifer from a hydrostatic high elevation down gradient to a hydrostatic low elevation. Drawdown: The lowering of the water level in a well as a result of pumping. It is the difference between the height of the water table and that of the water in a pumping well. EER: Energy Efficiency Rating. An important consideration when purchasing water softening systems. Emerging Contaminants: Newly recognized contaminants requiring EPA evaluation. Endocrine disruptors: A class of water pollutants that affect the human endocrine system. These include pesticides and emerging contaminants like pharmaceuticals and surfactants. Enteric: Of or within the intestine. Evaporite: A sediment deposited from an aqueous solution as a result of evaporation, such as rock salt and various other combinations of evaporated material typically containing mineral salts. Exempt Well: The Arizona Ground Water Management Law of 1980 identifies domestic wells as "exempt wells" because their owners don't have to report to authorities how much water they draw, and the wells are used only for domestic, or household, purposes. Owners of such a well are permitted to pump no more than 35 gallons a minute, or 18.4 million gallons a year. FDA: The U.S. Food and Drug Administration. Flocculation: Usually done before sedimentation. It involves the addition of flocculants and coagulants (chemicals) to form large particles (aggregates) from the fine solids suspended in water so they can settle quickly or be filtered faster. GPM: Gallons of water per minute (one gallon = 3.8 liters). Geologic formations: A body of rock strata that consists dominantly of one type of geologic material. For example, the Redwall Limestone Formation is a massive consolidated rock consisting of limestone and is found in the cliffs of the Grand Canyon and as a sedimentary layer in the Colorado Plateau. Half-life: The time period in which half the initial number of atoms of a radioactive element disintegrate into atoms of the daughter element. For example, Carbon 14 has a half-life of 5,730 ± 40 years, and after that period of time half of the original carbon will have disintegrated to nitrogen. Hardness: The total amount of calcium and magnesium ions found in water. Hard water affects detergents by limiting suds formation. Scale formation in pipes is accelerated by hard water. Some scale formation is desirable to protect pipes from corrosion. Excessive scaling clogs pipes and can short the life of home appliances. There is no drinking water standard for hardness. Hydrogen sulfide: A toxic, rotten egg smelling gas that occurs naturally in aquifers and sediments. Magma: Naturally occurring molten rock materials, generated within the earth and capable of intrusion and extrusion, from which igneous rocks have been derived through solidification. MCL: The maximum contaminant level or maximum concentration of a contaminant allowed in drinking water. Microorganisms: Organic carbon based organisms that are not visible with the naked eye, including bacteria and viruses. Minerals: Natural crystalline materials found in rocks (such as granite, marble, and sandstone) and soils (such as sand silt and clays). Minerals are composed of chemical elements like oxygen, silicon, aluminum, iron, and many other elements. NOM: Natural organic matter (mostly from plant and animal tissue decay) present most often in surface water sources and contaminated ground water. Colored water usually has high concentrations of NOM. NPDWS: National Primary Drinking Water Standards. NSDWS: National Secondary Drinking Water Standards. Organic chemicals or contaminants: Carbon-based compounds, including pesticides and oil-derived products (fuels, plastics, and solvents). This should not be confused with the popular used of the term “organic,” meaning food grown without pesticides. Overdraft: Ground water pumping at a rate that exceeds the rate of recharge. Pathogens: Microorganisms that produce diseases. Common pathogens regulated in drinking water include bacteria (such as Salmonella) and protozoan parasites (such as Giardia and Cryptosporidium). Note that water sources are commonly tested for the possible presence of pathogens by measuring total coliform bacteria. pCi/L: PicoCurie, a measurement of radioactivity. One picoCurie is 3.7x 10-2decays per second. Perchlorate: Found in rocket fuel and explosives, and has been found in both the ground water and surface water of several states. Perennial: A stream that flows throughout the year, a permanent stream. Permeability: The capacity of a porous rock, sediment, or soil for transmitting a fluid, it is a measure of the relative ease of fluid flow. pH: Values range from 1-14 units. Water with a pH of 7 is neutral, below 7 is acidic, and above is basic (usually alkaline). Most water sources in AZ have a basic pH (7-8.5) due to their natural alkalinity. Physiographic Province: A region of which all parts are similar in geologic structure and climate and which has had a unified geomorphic history; its physical features differ significantly from those of adjacent regions. Plutons: A large body of granitic rock originating from deep within the earth. POE: Point of entry. A device that treats all or most of the water entering the home. Pollutants: Unwanted contaminants and pathogens of anthropogenic origin that can be found in water, soil, and air. Pollutants are chemicals and organisms that have been associated with adverse environmental and health effects. Porosity: Porous geologic material containing voids, pores, fractures, or interstices which may or may not be interconnected. The ratio between the void space and the total volume is the porosity (typically stated as a percentage). POU: Point of use. Device that treats water at a particular tap source. ppm: Parts per million. Precipitation of a mineral: Opposite of dissolution. The mineral crystallizes and forms a solid again. Pure water: contains no measurable or detectable contaminants (minerals or pollutants) of any kind. Purified water: A vague and misused term. In general, a type of water which has been produced by distillation, deionization, reverse osmosis, or other suitable processes. Radon: A radioactive gas that may be present in ground water sources that come into contact with uranium-rich minerals. Recharge: The processes involved in the addition of water to the saturated zone of the aquifer, also the amount of water added. Reclaimed water: Comes from sewage that is processed using physical, biological, and chemical treatments at a sewage treatment plant. Risk assessment: A scientific process that estimates the chances of getting a disease from drinking water with a contaminant at a given concentration. Salinity: A measure of the quantity of dissolved salts (minerals) in water. Saline water: Exceeds 1000mb/L TDS or salts. Moderately saline water is referred to as brackish or briny. Scale: Hard residues that coat the inside of water pipes and appliances and is the result of the precipitation of minerals composed of calcium and magnesium carbonates. Hot water helps form scale. SDWA: Safe Water Drinking Act Sedimentary rock: A layered rock resulting from the consolidation of sediment, such as sandstone or limestone. Shock-chlorination: The circulation of strong chlorine-based (bleach) solution through the well casing and house plumbing. Soft water: Contains mostly sodium or potassium ions. Hard water can be “softened” by replacing calcium and magnesium for sodium or potassium ions using a water softener system. Water naturally low in TDS is also called soft water. Solubility: Describes the amount of a chemical or mineral that can be dissolved in water. Subsidence: The sinking or downward settling of the land surface that can be associated with ground water pumping. It causes damage to roads, buildings, utility infrastructure, and other underground infrastructure. Superfund: Superfund is the common name for the federal environmental law officially known as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, 42 U.S.C. § 9601-9675), enacted on December 11, 1980. The Superfund law paid for toxic waste cleanups at sites where no other responsible parties could pay for a cleanup by assessing a tax on petroleum and chemical industries. Table salt: A mineral composed of sodium and chloride ions. TCE: The abbreviation for the volatile industrial solvent trichloroethylene notorious for industrial ground water contamination. TDS: Total dissolved solids in milligrams per liter. Turbidity: A measure of the amount of suspended solids (particles) in water. EPA: The U.S. Environmental Protection Agency. USGS: The U.S. Geological Survey VOCs: Volatile organic chemicals such as chloroform, TEC and benzene. Volatile: A characteristic of organic chemicals that have boiling points lower than water. These include gasoline products, industrial solvents, and water disinfection by-products. Volatile organic chemicals are commonly abbreviated as VOCs. Well yield: The maximum pumping rate that can be supplied by a well without lowering the water level in the well below the pump intake or causing the well to go dry. WHO: The World Health Organization
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