Denver Water GlossaryFrequently Used Water Terms and Definitions Click on letter of alphabet to go to area of definition:
AWWA American Water Works Association. The drinking water industry's trade association; headquarters are in Denver. 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 of four for a year. Alluvial Water Ground water that is hydrologically part of a natural surface stream system. 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. Appropriation The right to take water from a natural stream or aquifer for beneficial use at a specified rate of flow, either for immediate use or to store for later use. Usually confirmed by a water court decree. (See also Prior Appropriation, Riparian Rights and Water Right.) 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. They may be alluvial or nontributary in nature. Ascending Block Rates (or Increasing Block Rates) A rate structure that divides a customer's water use into blocks, or consumption amounts, with the rate for each subsequent block priced higher than the previous block. Augmentation Plan A court-approved plan that allows a water user to divert water out of priority so long as adequate replacement is made to the affected stream system and water right in quantities and at times so as to prevent injury to the water rights of other users. Augmentation Source The supply of water used to replace depletions in an augmentation plan. Average Winter Consumption (AWC) The amount of water used on average by a customer during the winter; provides a good indication of indoor water use. Backflow Prevention Prevention of the flow of any foreign liquids, gases or substances into the distribution pipelines of a potable water supply; accomplished by an air gap or mechanical backflow obstacle. Beneficial Use Lawful and prudent use of water that has been diverted from a stream or aquifer for human or natural benefit. Block A volume of water used in setting water rates; a quantity or volume of water sold at a particular rate. Build Out The ultimate development of undeveloped areas within the Denver Water Combined Service Area. Bypass Flow Water that is allowed to flow past a diversion structure or storage facility. Call A demand that upstream water rights with more recent (junior) priority dates than the calling right cease diverting; the exercise of a senior water right holder in "calling" for his or her water rights, requiring junior water right holders to allow water to pass to the senior right holder. Citizen's Advisory Committee (CAC) A nine-member public standing committee that advises the Denver Board of Water Commissioners on policies and programs and facilitates public involvement in the review of the agency's activities. Members are appointed by the Board of Water Commissioners. Clean Water Act The federal law that establishes 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 for the country's waters from both point and non-point sources of pollution. Coliform A bacteria that originates in the digestive system of mammals. If found in water, it alerts lab technicians that pathogens might be present. Combined Service Area The area in which water service is provided by Denver Water, including the City and County of Denver and suburban areas served via contracts with Total Service, Read and Bill and Master Meter (wholesale) distributors. Includes both "in fill" and expansion areas that would logically be served by Denver Water in the future. Compact A formal agreement between states concerning the use of water in a river or stream that flows across state boundaries. Compact Call The requirement that an upstream state cease or curtail diversions of water from the river system that is the subject of the compact to satisfy the downstream state's compact entitlements. Conduit A 24-inch or larger diameter pipe carrying raw or potable water from or to treatment facilities, reservoirs and delivery points feeding a distribution system. 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." Consumption Pattern The variation in the amount of water a customer uses over time. Continental Divide An imaginary boundary line that runs north to south through the Rocky Mountains, separating rivers that flow west to the Pacific Ocean from those that flow south and east toward the Gulf of Mexico and the Atlantic Ocean. 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. Cumulative Impact Analysis A review of the cumulative environmental, social and economic impacts of proposed water projects and activities associated with development within an ecosystem or drainage area. Demand Forecast A prediction of future water use. Most water demand forecasting models are either directly or indirectly based upon projected changes in demographic data, such as population, etc. Demand Management Reductions of water usage accomplished either through temporary measures such as restrictions during a drought, or through long-term conservation programs. These include replacement of inefficient fixtures with more efficient fixtures such as 1.6 gallon toilets, installation and maintenance of landscapes that have low water requirements, or through changes in customer attitudes toward water conservation, leading to reduction in water use. Descending Block Rates (or Decreasing Block Rates) A rate structure that divides a customer's water use into blocks, or consumption amounts, with the rate for each subsequent block priced lower than the previous block. Designated Basin An area in which the use of ground water is assumed not to impact the major surface river basin to which the designated basin would otherwise be tributary. Much of eastern Colorado is in designated basins. Direct Flow (or Direct Right) Water diverted from a river or stream for use without interruption between diversion and use except for incidental purposes, such as settling or filtration. Distribution Main see Water Main. Distributor A suburban entity, generally quasi-municipal or municipal, with which Denver Water has contracted to provide water service outside of Denver. 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. Due Diligence The efforts necessary to bring an intent to appropriate water to fruition; actions that demonstrate a good faith intention to complete a diversion of water within reasonable time. Duty of Water The amount of water that through careful management and use, without wastage, is reasonably required to be applied to a tract of land for a length of time that is adequate to produce the maximum amount of the crops that are ordinarily grown there. Effluent The water leaving a water or wastewater treatment plant. Effluent Exchange The practice of using wastewater effluent as a replacement source for diversion of water upstream. Endangered Species Act The federal law that sets forth how the United States will protect and recover animal and plant species whose populations are in dangerous decline or close to extinction. The law protects not only threatened and endangered species but also the habitat upon which species depend. Energy Policy Act (EPACT) The 1992 federal law that states, among other things, that no toilet manufactured after January 1, 1994, shall use more than 1.6 gallons per flush (except "blowout" toilets and commercial toilets), and that showerheads and faucets manufactured after January 1, 1994, may not use more than 2.5 gallons per minute. Environmental Impact Statement (EIS) Detailed analysis of the impacts of a project on all aspects of the natural environment required by federal National Environmental Policy Act for federal permitting or use of federal funds. Exchange A process by which water, under certain conditions, may be diverted out of priority at one point by replacing a like amount of water at a downstream location. Expansion Undeveloped areas adjacent to the boundaries of existing distributor contract areas that those distributors would logically be expected to serve in the future and that have been included in the Combined Service Area. FERC Federal Energy Regulatory Commission; formerly the Federal Power Commission. 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 that the lands be managed in a manner to protect the quality of scientific, scenic, historical, ecological, environmental, water resource and archaeological values. Finished Water Treated potable water that is considered safe and suitable for delivery to consumers. Firm Annual Yield The yearly amount of water that can be dependably supplied from the raw water sources of a given water supply system. Flat Rates The rate when customers are charged the same amount per bill based on a pre-determined formula (square footage, irrigable area and water-using devices) rather than being charged for actual consumption. Flume A sloped channel that is utilized to convey water and is commonly constructed of wood or concrete. Some specialized flumes are used to measure flow (e.g. Parshall flume) by means of a calibrated throat or cross section (See also Weir.) Futile Call A situation in which a junior (more recent) priority is allowed to continue to divert in spite of a downstream senior call when curtailing the junior would not produce any additional water for the senior. Gallons Per Account Per Day (GAD) A term generally used to approximate the average amount of water used by a customer account on a daily basis. The formula used to determine GAD is: Total Treated Water Delivered (over a year)
Gallons Per Capita Per Day (GCD) A term generally used to approximate the average amount of water used per day, per person, over a period of one year. It is generally compiled only on a system wide basis. The formula used to determine GCD is: Total Treated Water Delivered (over a year)
Ground Water Water found below the surface of the Earth. 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. In Fil Undeveloped areas within the combined service area that Denver Water would be expected to serve in the future. Integrated Resource Planning (IRP) A method for looking ahead using environmental, engineering, social, financial and economic considerations; includes using the same criteria to evaluate both supply and demand options while involving customers and other stakeholders in the process. Junior Rights Water rights that were obtained more recently and therefore are junior in priority to older or more senior rights. (See Priority) KAF One thousand acre feet. 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. Master Meter Distributors outside the city limits of the City and County of Denver who receive water service from Denver Water under agreements whereby the distributor operates and maintains the water distribution systems to supply individual customers. Denver Water bills only the distributor for water delivered through large master meters, and the distributors establish the rates for and bill the customer. Maximum Contaminant Level The highest allowable amount of a constituent in water. Drinking water quality criteria are established by the U.S. Environmental Protection Agency as regulatory standards. Miner's Inch (or Statutory Inch) A measurement of water flow. In Colorado, 38.4 miner's inches is considered equivalent to one cubic foot per second. Multi-Family Residential A planning term used to describe a building in which two or more families live in separate but attached dwellings, e.g., apartment houses, townhomes and condominiums. National Pollution Discharge Elimination System (NPDES) Permit A permit required under Section 401 of the Clean Water Act regulating discharge of pollutants into the nation's waterways. 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. Natural Replacement The ordinary replacement of older, less efficient water fixtures (toilets, faucets, etc.) with new, more efficient fixtures as the older fixtures wear out, break or are replaced. Net Demand The water demand that is expected to occur in the future after reductions for natural replacement and conservation. It represents the actual demand that should be experienced in the future at customers' premises. Usually expressed in thousand acre feet (KAF). Non-Consumptive Use Water drawn for use that is not consumed, such as water diverted for hydroelectric generation. It also includes such uses as boating and fishing, where water is still available for other uses at the same site. Non-Point Source The source of pollution discharged over a wide land area, not from one specific area, that finds its way into streams, lakes and oceans, such as runoff from streets, parking lots, lawns, agricultural land, individual septic systems and construction sites. Nonpotable Water not suitable for drinking. (See also Potable, Reuse.) Non-Tributary Ground Water Underground water in an aquifer that neither draws from nor contributes to a natural surface stream in any measurable degree. Participation Agreement An agreement in which a distributor or developer pays for the cost of the distribution facilities such as conduits, treated water reservoirs or pump stations required to provide service within that district from the nearest existing available source. 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.) Point Source The source of pollution discharged from any identifiable point, including ditches, channels, sewers, tunnels and containers of various types. Potable Water that does not contain pollution, contamination, objectionable minerals or infective agents and is considered safe for domestic consumption; drinkable. (See also Nonpotable, Reuse.) Pressure Pipe Pipe used to distribute potable water throughout the city for fire fighting and domestic purposes. 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. Pressure Zone Geographical area within a water distribution system defined by a number of valves with at least two feeds. Prior Appropriation The water law doctrine that confers priority to use water from natural streams based upon when the water rights were acquired. Water rights in Colorado and other western states are confirmed by court decree; holders of senior rights have first claim to withdraw water over holders who have filed later claims. (See also Water Right, Riparian Rights, Priority and Appropriation) Priority The right of a senior water rights holder to divert from a natural stream before a Projected Savings An estimate of the amount of water that will not be used because both suppliers and customers are implementing certain efficiency practices. Ramping Controlling streamflow so that flow changes are gradual and do not adversely impact safety and property downstream. Rated Capacity The volume of water a treatment plant is capable of producing under normal operating conditions. Raw Water Untreated water. Read and Bill Distributor Distributors outside the city limits of Denver who receive water service from Denver Water under agreements in which the distributor operates and maintains portions of the system used to supply individual customers, and Denver Water is responsible for billing each customer on an individual basis. Reservoir A body of water used to collect and store water, or a tank or cistern used to store potable water. Reservoir Surcharge Water in a reservoir that resides above the spillway. Retrofit An umbrella term that refers to the modification of something for more efficiency. In the case of water conservation, retrofit refers to modifications to plumbing fixtures to increase efficiency. Return Flows Water that returns to a stream after it has been used. Reuse To use again; recycle; to intercept, either directly or by exchange, water that would otherwise return to the stream system, for subsequent beneficial use. (See also Potable, Nonpotable.) Reverse Osmosis A water treatment technique that forces water through a dense membrane to remove impurities. Riparian Rights Water rights that are acquired together with title to the land bordering a source of surface water; the right to put to beneficial use surface water adjacent to one's land. Riparian rights are most common in states east of the Mississippi River and do not exist in Colorado. (See Appropriation, Prior Appropriation and Water Right.) Run-off Water that flows on the surface of the Earth into streams, rivers, lakes and oceans. 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. Safety Factor An amount of water added to demand projections to protect against unforeseen changes in water supply and demand. Secondary Treatment Treatment of wastewater to a nonpotable level so that it may be returned to the stream. (See also Tertiary Treatment, Nonpotable.) Sludge A semi-liquid mass of accumulated settled solids deposited from the treatment plant process. Most water treatment plant sludge is inert and can be used as components in some manufactured products and as a base for fertilizer. Also called "residual solids." Spill Water Water released from a reservoir because the reservoir lacks sufficient storage capacity. Statutory Inch See Miner's Inch. Storage Water held in a reservoir for later use. Supply Management Methods by which a utility maximizes use of available untreated water. Surface Water Water located on the Earth's surface. Sustainability A decision-making concept describing development that meets the needs of the present without compromising the ability of future generations to meet their own needs. System Development Charge (SDC) A one-time connection charge that provides a means for financing a portion of the source of supply, raw water transmission facilities, treatment plants and backbone treated water transmission facilities required to provide service to a new customer. Sometimes called a tap fee. System Loss An amount of water, expressed as a percentage, lost to leaks, seepage and unauthorized use. Systemwide Environmental Impact Statement (SEIS) The result of a Foothills Agreement requirement that federal agencies conduct an Environmental Impact Statement analysis to determine the cumulative effects of the entire Denver Water system prior to the permitting of new water supply projects. The SEIS was initiated in 1981. When Denver requested permits for the Two Forks Dam and the Williams Fork Extension Project in 1984, all three studies were combined into one document, the Metropolitan Denver Water Supply EIS. Tap A physical connection made to a public water distribution system that provides service to an individual customer. Tap Allocation The process used for distributing 3/4-inch taps among applicants when shortages of treatment, transmission or distribution facilities and/or water supplies require a method of rationing taps. Tap Fee See System Development Charge. Ten-Acre Rule A policy implemented by Denver Water that requires Board approval for the use of potable water to irrigate tracts of land of ten acres or larger. Requires that any new development or renovation of ten acres or more be reviewed and approved for landscaping by the Board of Water Commissioners. Approval is contingent on demonstrating that an alternative source to irrigation with potable water is not reasonably or practically available and that the irrigation is designed to maximize efficiency. Tertiary Treatment Treatment of wastewater to a level beyond Secondary Treatment but below Potable. (See also Secondary Treatment, Nonpotable, Potable.) Total Service Distributor Distributors outside the city limits of Denver who receive water service from Denver Water under agreements in which Denver Water operates and maintains all of the systems used to supply the distributor in a manner to provide complete and total service, just like that furnished inside Denver. Trans-Basin Diversion The conveyance of water from its natural basin into another basin. Trans-Mountain Diversion The conveyance of water from one watershed to another, usually from the Western Slope to the Front Range. 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. Turbidity A measure of suspended solids in water; cloudiness. Unaccounted-For Water The difference between the total amount of water leaving treatment facilities and the total amount of water measured at customers' meters. Besides system losses, it also includes beneficial uses such as unmetered fire fighting and water used in system maintenance, along with meter under-registration. Unconstrained Demand The demand that would be experienced were it not for conservation and natural replacement. Usually expressed in thousand acre feet (KAF). Uniform Block Rates A rate structure that charges the same rate for all blocks of water consumption. Urban Runoff Water from an urban area that neither infiltrates the soil nor is consumed, but flows into a storm sewer or open waterway. Valve Mechanical device for controlling or stopping flow of water in a pipe. Water Audit A service provided by Denver Water to its customers that identifies water waste and leaks and offers ways to conserve water. Water Balance Allocation of water uses by specific sites to compare with meter records. Water Main (or Distribution Main) A 12-inch or smaller diameter pipe along public streets or appropriate rights-of-way used for distributing water to individual customers. Water Right A property right to make beneficial use of a particular amount of water with a specified priority date. (See also Appropriation, Prior Appropriation and Riparian Rights ) Watershed An area from which water drains and contributes to a given point on a stream or river. WaterWiser The Water Efficiency Clearinghouse. A source of information in print and/or electronic media accessible by phone, fax or Internet, sponsored by the American Water Works Association and the U.S. Environmental Protection Agency. (1-800-559-9855) Weir A vertical structure in an open channel with a calibrated opening that measures water's rate of flow. (See also Flume.) Wetlands Areas with standing water or a high water table that under normal circumstances support vegetation typically adapted to saturated soil conditions; generally includes swamps, marshes, bogs and areas with vegetation that grows in or around water. Xeriscape Landscaping concept that requires less water on vegetation that is suited to soils and climate. The term was developed by Denver Water in 1981. It is derived from the Greek word Xeros, meaning dry. 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. |