Where Your Water Comes From		Glossary of Water Terms		The Path Our Water Takes		About Groundwater

GLOSSARY OF WATER TERMS

A

• Abandoned well - A well that has been permanently discontinued or which is in a state of disrepair such that it cannot be used for its intended purpose.
• Abatement - Reducing the degree, intensity of, or eliminating pollution.
• Acid - A substance that has the ability to react with bases to form salt. The pH of an acidic solution is less than 7. pH 7 is neutral (e.g., pure water). Acids are pH 0 to less than 7. Similarly, bases are greater than 7 to 14. The usual definition of an acid is “any substance that can donate a hydrogen ion.”
• Acid Deposition ("acid rain") - Water that falls to or condenses on the Earth's surface as rain, drizzle, snow, sleet, hail, dew, frost, or fog with a pH of less than 5.6.
• Acidic -The condition of water or soil which contains a sufficient amount of acid substances to lower the pH below 7.0.
• Acre-foot (AF) - A common water industry unit of measurement. An acre-foot is 325,851 gallons, or the amount of water needed to cover one acre with water one foot deep. An acre-foot serves annual needs of two typical California families.
• Active Ingredient - The component which targets, kills or otherwise controls pests in any pesticide product. Pesticides are regulated primarily on the basis of active ingredients.
• Aeration - The addition of air to water or to the pores in soil.
• Age Tank - A tank used to store a known concentration of a chemical solution for feed to a chemical feeder. Also known as a day tank.
• Agricultural Pollution - The liquid and solid wastes from farming, including: runoff and leaching of pesticides and fertilizers; erosion and dust from plowing; animal manure and carcasses; crop residue; and debris.
• Algae - Microscopic plants which contain chlorophyll and float or suspend in water. Excess algae growths can impact taste and odor of potable water. Their biological activities affect the pH of and dissolved oxygen in the water.
• Alkali - Any of certain soluble salts, principally of sodium, potassium, magnesium, and calcium, which have the property of combining with acids from neutral salts and may be used in chemical water treatment processes.
• Alkaline - The quality of being bitter due to alkaline content (pH is greater than 7).
• Alum (Al2(SO4)3•14 H2O) - The common name for aluminum sulfate, a chemical used in the coagulation process to remove particles from water.
• Aqueduct - Man-made canal or pipeline used to transport water.
• Aquifer - An underground geologic formation of rock, soil or sediment that is naturally saturated with water; an aquifer stores groundwater.
• Arsenic - A naturally occurring element in the environment. Arsenic in drinking water commonly comes from natural sources in the ground, but some can come from industrial pollution. At high concentrations it can cause cancer.

B

• Bacterium - A microscopic unicellular organism that lacks a nuclear membrane. Some can cause disease.
• Bacteria - Plural of bacterium.
• Base - A substance that has a pH value between 7 and 14.
• Bedrock - The solid rock that underlies all soil, sand, clay, gravel and other loose materials on the earth's surface. Unfractured bedrock is impermeable while fractured bedrock may store and transmit groundwater.
• Blackwater - Water that contains animal, human or food wastes.
• BMPs - Best Management Practices. Generally, a set of standardized efficiencies or measures. At CLWA and other urban water suppliers, refers to a set of water conservation measures agreed to by participants in the California Urban Water Conservation Council.
• Brackish - A mixture of freshwater and saltwater.
• Buffer - A solution or liquid whose chemical makeup neutralizes acids or bases without a great change in pH.

C

• California Environmental Quality Act (CEQA) - Requires an assessment of the possible environmental impacts of projects.
• California Plan - Officially "California’s draft Colorado River Water Use Plan," also sometimes called the "4.4 Plan." A 2003 planning document designed to reduce California’s reliance on surplus Colorado River water over the next 15 years through conservation, water transfers, and conjunctive use measures.
• Capillarity - The process by which water rises through rock, sediment or soil caused by the cohesion between water molecules and an adhesion between water and other materials that "pulls" the water upward.
• CUWCC - California Urban Water Conservation Council. Created to increase efficient water use statewide through partnerships between urban water agencies, public interest organizations and private entities. The Council's goal is to integrate urban water conservation Best Management Practices into the planning and management of California's water resources.
• Centrifuge - A mechanical device that uses centrifugal or rotational forces to separate substances of different densities, such as solids from liquids or liquids from other liquids.
• CFS - Cubic Feet per Second.
• Chloramination - The treatment of a substance, such as drinking water, with chlorine and ammonia (chloramines) in order to kill disease-causing organisms.
• Chloride (Cl–) - One of the major anions commonly found in water and wastewater. Its presence is often determined by ion chromatographic or volumetric analysis. Consumers who drink water with concentrations of chloride exceeding a secondary maximum contaminant level of 250 milligrams per liter may notice a salty taste.
• Chlorination - The treatment of a substance, such as drinking water, with chlorine in order to kill disease-causing organisms.
• Chromium - A naturally occurring element found in air, soil, water and food.
• Chromium VI - AKA "chrome 6." One of the most common species of chromium. Exposure to airborne chromium VI compounds in industrial settings is known to cause cancer. The evidence of its carcinogenicity by ingestion is not compelling. The U.S. Environmental Protection Agency determined that chromium VI was not carcinogenic by ingestion of food or drinking water.
• Clarity - Clearness of liquid, as measured by a variety of methods.
• Coagulation - The process, such as in treatment of drinking water, by which dirt and other suspended particles become chemically “stuck together” so they can be removed from water.
• Coliform bacteria - Bacteria of the family Enterobacteriaceae, commonly found in the intestinal tracts of warm-blooded animals. In sanitary bacteriology, these organisms are defined as all aerobic and facultative anaerobic, gram-negative, nonspore-forming, rod-shaped bacteria that ferment lactose with gas and acid formation within 48 hours at 95° Fahrenheit (35° Celsius).
• Color - A physical characteristic describing the appearance of water (different from turbidity, which is the cloudiness of water). Color is frequently caused by fulvic and humic acids.
• Condensation - Water vapor changing back into liquid.
• Condensation Surfaces - Small particles of matter, such as dust and salt suspended in the atmosphere, which aid the condensation of water vapor in forming clouds.
• Confined Aquifer - An aquifer that is bound above and below by dense layers of rock and contains water under pressure.
• Conjunctive Use – Use or storage of runoff or imported water, in conjunction with groundwater in a local aquifer, to offset use of groundwater or to store groundwater for later retrieval and use.
• Contour Plowing - Plowing done in accordance with the natural outline or shape of the land by keeping the furrows or ditches at the same elevation as much as possible to reduce runoff and erosion.
• Corrosivity - An indication of the corrosiveness of water. The corrosiveness of water is described by the water’s pH, alkalinity, hardness, temperature, total dissolved solids, dissolved oxygen concentration, and Langelier saturation index.
• Cryptosporidium - A group of widespread intestinal coccidian protozoan parasites about 5 micrometers in diameter, causing diarrhea and capable of infecting humans, birds, fish, and snakes. It is responsible for waterborne disease outbreaks.
• CT – Contact Time. The product of disinfectant concentration (in milligrams per liter) determined before or at the first customer and the corresponding disinfectant contact time (in minutes). It is also called the CT value. Units are milligram minutes per liter.
• Cubic foot - A frequent water industry term of measurement, as in cubic feet per second. One cubic foot (CF) equals 7.48 gallons. A cubic foot per second is 450 gallons per minute.
• CUWA - California Urban Water Agencies. Group of 11 member agencies serving two-thirds of state's population.
• CVP - Central Valley Project. A series of dams, reservoirs and canals in the San Joaquin Valley of California.
• Cyst - The infectious stage for Giardia, 7 to 10 micrometers long and refractile to light when viewed with a brightfield microscope.

D

• Delta - Fan-shaped area at the mouth of a river. A California example is the Sacramento-San Joaquin Delta east of San Francisco Bay.
• Deposition - The process of dropping or getting rid of sediments by an erosional agent such as a river or glacier; also called sedimentation.
• Desalination - The process of removing salt from seawater or brackish water.
• Discharge - The amount of water flowing past a location in a stream/river in a certain amount of time - usually expressed in liters per second or gallons per minute.
• Disinfectant - An agent that destroys or inactivates harmful microorganisms.
• Disinfection By-Product (DBP) - A chemical by-product of the disinfection process. Disinfection by-products are formed by the reaction of the disinfectant, natural organic matter, and the bromide ion (Br–). Some disinfection by-products are formed through halogen (e.g., chlorine or bromine) substitution reactions; i.e., halogen-substituted by-products are produced. Other disinfection by-products are oxidation by-products of natural organic matter (e.g., aldehydes—RCHO). Concentrations are typically in the microgram-per-liter or nanogram per-liter range.
• Disinfection By-Product Precursor (DBPP) - A substance that can be converted into a disinfection by-product during disinfection. Typically, most of these precursors are constituents of natural organic matter. In addition, the bromide ion (Br–) is a precursor material. See also bromide; disinfection by-product; natural organic matter.
• Drought - A prolonged period of below-average precipitation.
• DWR - California Department of Water Resources. Guides development and management of California’s water resources; owns and operates the State Water Project.

E

• Ecosystem - An interacting network of groups of organisms together with their nonliving or physical environment.
• EIR - Environmental Impact Report; a state-mandated written summary of the positive and negative effects on the environment caused by the construction and operation of a project.
• Endangered Species - A species of animal or plant threatened with extinction.
• Erosion - The processes of picking up, moving, shaping and depositing sediments by various agents; agents of erosion include streams, glaciers, wind and gravity.
• Escherichia coli (E. coli) - A gram-negative, facultatively anaerobic, non-spore-forming bacillus commonly found in the intestinal tracts of humans and other warm-blooded animals. In sanitary bacteriology, Escherichia coli is considered the primary indicator of recent fecal pollution.
• Evaporation - Water changing into vapor and rising into the air.

F

• Fallowing - A program to generate water by paying farmers to fallow land, i.e., not grow crops. The water not used for irrigation is then transferred to urban areas or stored for future use.
• FERC - Federal Energy Regulatory Commission. An independent regulatory agency within the Department of Energy.
• Ferric Chloride (FeCl3) - An iron salt used as a coagulant in water treatment. The iron has a valence of +3.1.
• Filtration - Passing water through coal, sand and gravel to remove particles.
• Floc - Clumps of impurities removed from water during the purification process; formed when alum is added to impure water.
• Flocculation - A step in water filtration in which alum is added to cause particles to clump together.
• Floodplain - Area formed by fine sediments spreading out in the drainage basin on either side of the channel of a river as a result of the river’s fluctuating water volume and velocity.

G

• Giardia - The genus name for a group of single-celled, flagellated, pathogenic protozoas found in a variety of vertebrates, including mammals, birds, and reptiles. These organisms exist either as trophozoites or as cysts, depending on the stage of the life cycle.
• Groundwater - Water that has percolated into natural, underground aquifers; water in the ground, not a puddle of water on the ground.
• Groundwater Recharge or Replenishment - Pumping or percolating storm water runoff or imported water into an aquifer to replenish its supplies.

H

• Haloacetic Acid (HAA) - (CX3COOH, where X = Cl, Br, H in various combinations). A class of disinfection by-products formed primarily during the chlorination of water containing natural organic matter. When bromide (Br–) is present, a total of nine chlorine-, bromine-and-chlorine-, or bromine-substituted species may be formed. Trihalomethanes and haloacetic acids are the two most prevalent classes of by-products formed during chlorination and are subject to regulation under the Disinfectant/Disinfection by-products rule.
• Hardness - A characteristic of water determined by the levels of calcium and magnesium. The scaling or white deposits that accumulate on coffee pots, water heaters and plumbing fixtures resulting from such mineral salts dissolved in water.
• Heterotrophic Plate Count (HPC) - A bacterial enumeration procedure used to estimate bacterial density in an environmental sample, generally water. Other names for the procedure [within the water industry] include total plate count, standard plate count, plate count, and aerobic plate count.
• Hydroelectric Plant - A power plant that produces electricity from the power of rushing water turning turbine generators.
• Hydrology - The scientific study of the behavior of water in the atmosphere, on the Earth's surface and underground.

I

• Immunofluorescence - The emission of visible light by a compound that has been irradiated with ultraviolet light. For example, a fluorescent compound (i.e., a fluorescein) can be attached to an antibody. Bacterial, viral, or other antigens that react with the antibody can then be observed by illuminating the sample with ultraviolet light.
• I/O - Inlet-outlet facility at a reservoir.
• Inorganic - Pertaining to material such as sand, salt, iron, calcium salts, and other mineral materials. Inorganic substances are of mineral origin, whereas organic substances are usually of animal or plant origin and contain carbon.
• Irrigation - Supplying water to agriculture by artificial means; for example, pumping water onto crops in an area where rainfall is insufficient.

L

• Leach - To remove components from the soil by trickling water through it.
• Legionella - A genus of bacteria of the family Legionellaceae. It currently consists of at least 51 serogroups comprising 34 species. It has the ability to colonize water in distribution systems (heating tanks, cooling towers, air conditioning lines, etc). It can cause disease in humans (e.g., Legionnaires’ disease or Legionellosis) that is progressive and sometimes fatal, or a milder form of pneumonic illness (Pontiac fever) that is self-limited (i.e., heals on its own) with respiratory symptoms similar to influenza.

M

• MAF - Million acre-feet.
• Marginal Land - Land which, in its natural state, is not well suited for a particular purpose, such as raising crops.
• MCL - Maximum Contaminant Level. According to health agencies, the maximum amount of a substance that can be present in water that's safe to drink and which looks, tastes and smells good.
• MGD - Million gallons per day; a measure used for water treatment plants and other facilities.
• Microbiological - Relating to microorganisms and their life processes.
• Microorganism - An organism of microscopic size, such as a bacterium.
• Mitigation - A way in which an agency may offset negative environmental impacts of a project or make the impacts less serious.
• Monterey Agreement - A December 1994 statement of principles to settle disputes over water allocations and operational aspects of the State Water Project, providing greater water management flexibility and financial stability.
• MTBE - Methyl tertiary butyl ether. An oxygenate used in California gasoline to help prevent air pollution. The chemical has a long life and has been determined to have polluted lakes, reservoirs and groundwater after leaking from watercraft, underground tanks and pipelines. Required to be phased out by Dec. 31, 2002.
• Mulch - Material spread on the ground to reduce soil erosion and evaporation of water; includes hay, plastic sheeting and wood chips.
• MWQI - Municipal Water Quality Investigation. Government agencies conduct water quality studies in the Sacramento River watershed, the Sacramento-San Joaquin Delta, and the San Francisco Bay Area.

N

• Natural Environment - All living and nonliving things that occur naturally on the earth.
• Nitrate (NO3–) - An oxidized ion of nitrogen. Nitrifying bacteria can convert nitrite (NO2–) to nitrate in the nitrogen cycle. Sodium nitrate (NaNO3) and potassium nitrate (KNO3) are used as fertilizer. Thenitrate ion is regulated by the US Environmental Protection Agency.
• Nitrite (NO2–) - An intermediate oxidized ion of nitrogen. Nitrifying bacteria can convert ammonia (NH3) to nitrite (NO2–) to nitrate (NO3–) in the nitrogen cycle. Sodium nitrite (NaNO2) is used in curing meats. The nitrite ion is regulated by the US Environmental Protection Agency.
• Nonpoint Source Pollution - Pollution which comes from diffuse sources such as urban and agricultural runoff.

O

• Odor Threshold - The minimum odor of a water sample that can just be detected after successive dilutions with odorless water. The odor threshold is reported as the threshold odor number.
• Oocyst - A structure that is produced by [some] coccidian protozoa (i.e., Cryptosporidium) as a result of sexual reproduction during the life cycle. The oocyst is usually the infectious and environmental stage, and it contains sporozoites. For the enteric protozoa, the oocyst is excreted in the feces.
• Organic Chemical - A chemical having a carbon–hydrogen structure.
• Ozone - A gas derived from oxygen that is bubbled through water during the treatment processes to kill microorganisms.

P

• Parameter - A water quality attribute. For example, the presence of certain bacteria, the hardness, and the level of sodium are all parameters.
• Pathogen - An infectious agent. An organism capable of causing infection or infectious disease.
• Perchlorate - A chemical used in manufacturing rocket fuel that has contaminated some California groundwater basins. Perchlorate interferes with iodide uptake into the thyroid gland. The disruption of thyroid functions leads to changes in metabolism in adults and normal growth and development in children.
• pH - A relative scale of how acidic or basic (alkaline) a material is; the scale goes from 0 to 14; 7 is neutral, acids have pH values less than 7 and bases have pH values higher than 7.
• Pipeline - Carries water above or underground to homes and businesses.
• Potable - Drinkable. Non-potable means non-drinkable.
• Precipitation – Water that has condensed as water vapor in the atmosphere and then falls to the earth in the form of rain or snow.
• Protozoan - Single-celled, animal-like, eukaryotic organisms of the kingdom Protista. Protozoans can occur wherever moisture exists. There are many parasites and commensals of plants and animals, as well as free-living species. They cause a number of diseases, such as African sleeping sickness, malaria, and dysentery. They are an economically and scientifically important group. It is thought that the organisms of the kingdom Animalia evolved from ancestors which were protozoans.
• Pumping Lift - Distance water must be lifted in a well from the pumping level to the ground surface.
• Pumping Plant - Facility that lifts water up and over hills or up a gradient against gravity.

R

• Recharge - Replenishing an aquifer with stormwater or imported water.
• Recycled Water - Wastewater that has been cleaned so that it can be reused for most purposes except drinking.
• Recycled - Wastewater cleaned for re-use, usually for nonpotable purposes such as irrigating landscape and refilling aquifers.
• Reservoirs - A pond or lake where water is collected and stored until it is needed.
• Residuals - Any gaseous, liquid, or solid by-product of a treatment process that ultimately must be disposed of. For example, in a fixed-bed filter for removing particles from water, both the filter backwash water and the solids in the backwash water are residuals.
• Rills - Small grooves, furrows, or channels in soil made by water flowing down over its surface; also another name for a stream - usually a small stream.
• Runoff - Liquid water that travels over the surface of the Earth, moving downward due to the law of gravity; runoff is one way in which water that falls as precipitation returns to the ocean.

S

• SCAG - Southern California Association of Governments. It has evolved as the largest of nearly 700 councils of government in the United States, functioning as the Metropolitan Planning Organization for six counties. As the designated Metropolitan Planning Organization, the Association of Governments is mandated by the federal government to research and draw up plans for transportation, growth management, hazardous waste management and air quality. Additional mandates exist at the state level.
• Salinity - Refers to the amount of salt in the water.
• Source water - The supply of water for a water utility. Source water is usually treated before distribution to consumers, but some groundwater is of such a quality that it can be distributed untreated.
• Standard - (1) A recommended practice in the manufacturing of products or materials or in the conduct of a business, art, or profession. Such standards may or may not be used as (or called) specifications. (2) A document that specifies the minimum acceptable characteristics of a product or material, issued by an organization that develops such documents (e.g., an American Water Works Association standard). (3) A numerical contaminant limit set by a regulatory agency (e.g., a US Environmental Protection Agency maximum contaminant level).
• Strategic Plan - The product of a strategic planning process; a comprehensive approach to how CLWA does business. The strategic plan relates the mission statement of CLWA to goals and objectives to be achieved during each fiscal year.
• Sulfate (SO42–) - An inorganic ion that is widely distributed in nature. It may be present in natural waters in concentrations ranging from a few to several thousand milligrams per liter.
• Surface Runoff - Water flowing along the ground into rivers, lakes and oceans.
• Surface Water - All water, fresh and salty, on the Earth's surface.
• SWP - State Water Project which is owned and operated by the California Department of Water Resources.
• SWRCB - State Water Resources Control Board. Regulates water quality and water rights to protect beneficial water use in the Bay/Delta estuary.

T

• THMLs - Total trihalomethanes. By-products of chlorination.
• Topsoil - The top layer of soil; topsoil can grow better crops partly because it has more organic matter (humus), allowing it to hold more water than lower soil layers.
• Total Chlorine Residual - The total amount of chlorine residual present after a given contact time in a water sample, regardless of the type of chlorine. See also residual chlorine; total chlorine.
• Total Coliform Rule (TCR) - A rulemaking of the US Environmental Protection Agency that sets National Primary Drinking Water Regulations for total coliforms, fecal coliforms, and Escherichia coli. The rule was promulgated June 29, 1989 (54 Federal Register 27544–27568) and amended Jan. 15, 1991 (56 Federal Register 1556–1557).
• Total Coliforms (TC) - The group of bacteria used as warm-blooded animal fecal pollution indicator organisms of drinking water quality. Total coliforms are regulated by the US Environmental Protection Agency.
• Total Dissolved Solids (TDS) - Refers to the amount of minerals in water that will not settle out but remain in the water indefinitely.
• Total Organic Carbon (TOC) - A measure of the concentration of organic carbon in water, determined by oxidation of the organic matter into carbon dioxide (CO2). TOC includes all the carbon atoms covalently bonded in organic molecules. Most of the organic carbon in drinking water supplies is dissolved organic carbon, with the remainder referred to as particulate organic carbon. In natural waters, total organic carbon is composed primarily of nonspecific humic materials. Total organic carbon is used as a surrogate measurement for disinfection by-product precursors, although only a small fraction of the organic carbon will react to form these by-products. Quantitatively, total organic carbon is determined by removing interfering inorganic carbon, such as bicarbonate (HCO3–), and oxidizing the organic carbon to carbon dioxide. Typically, the carbon dioxide is then measured with a nondispersive infrared detector.
• Total Trihalomethanes (TTHM) - The sum of the four chlorine and bromine-containing trihalomethanes (i.e., chloroform, bromodichloromethane, dibromochloromethane, and bromoform). The US Environmental Protection Agency regulates the sum of these four species on a weight concentration basis.
• Transpiration - Evaporation of water through the leaves of plants.
• Trihalomethanes - Organic compounds which may be harmful to health at certain levels in drinking water.
• Turbidity - The state of having sediment or foreign particles suspended or stirred up in water.

U

• ULF - Ultra-low-flow, as in water-saving toilet fixtures. Currently ULF toilets use 1.6 gallons per flush.
• Unconfined Aquifer - An aquifer that discharges and recharges with an upper surface that is the water table.
• UWMP - Urban Water Management Plan. State law requires that every urban water supplier of a certain size prepare and adopt a water management plan every five years.

V

• Virus - (1) A minute organism not visible by light microscopy. A virus is an obligate parasite dependent on nutrients inside cells for its metabolic and reproductive needs. It consists of a strand of either deoxyribonucleic acid or ribonucleic acid, but not both, [inside] a protein covering called a capsid.

W

• Wash Water - Water that is used to clean a process unit. Wash water is typically identified as backwash water and is associated with the wastewater resulting from the cleaning of filter media to remove attached particles.
• Wastewater - Water that has waste material in it.
• Water Cycle - The movement of water from the air to and below the Earth's surface and back into the air.
• Water Reclamation - Treating wastewater so that it can be used again.
• Watershed - A geographical portion of the Earth's surface from which water drains or runs off to a single place like a river; also called a drainage area.

X

• Xeriscape - Landscaping that requires little water from irrigation.

Z

• Zone of Aeration - The portion of the ground from the Earth’s surface down to the water table - the zone of aeration is not saturated with water because its pores are filled partly by air and partly by water.
• Zone of Saturation - The portion of the ground below the water table where all the pores in rock, sediment, and soil are filled with water.