absolute water right: A property right to put water to beneficial use with a specified priority date.

acre-foot: Volumetric measurement of water used for quantifying reservoir storage capacity and historical consumptive use. This is the amount of water that will cover an acre of land at a depth of 1 foot (43,560 cubic feet), or 325,851 gallons of water.

adjudication: To hear and settle a case by judicial procedure.

algae: Chlorophyll-bearing nonvascular, primarily aquatic species that have no true roots, stems, or leaves; most algae are miroscopic, but some species can be as large as vascular plants.

alkali: a soluble salt or a mixture of soluble salts present in some soils of arid regions in quantity detrimental to agriculture.

alkalinity: Generally, refers to the sum of the concentration of bicarbonate and carbonate of an aqueous solution.

alluvial aquifer: A water-bearing deposit of unconsolidated material (sand and gravel) left behind by a river or other flowing water.

alluvial water: Ground water that is hydrologically part of a surface stream that is present in permeable soil material, usually small rock and gravel.

alluvium: Deposits of clay, slit, sand, gravel or other particulate rock material left by a river in a streambed, on a flood plain, delta, or at the base of a mountain.

amalgamation: The dissolving or blending of a metal (commonly gold and silver) in mercury to separate it from its parent material.

ambient: Natural concentration of water quality constituents prior to mixing of either point or non point source load of contaminants or completely enveloping. From a time series of measurements of a parameter at a given location the ambient value is the 85th percentile.

ammonia: A compound of nitrogen and hydrogen (NH3) that is a common by-product of animal waste. Ammonia readily converts to nitrate in soils and streams.

anomalies: As related to fish, externally visible skin or subcutaneous disorders, including deformities, eroded fins, lesions and tumors.

Anthropogenic: Occurring because of, or influenced by, human activity.

Appropriate: (verb) To take the legal actions necessary to create a right to take water from a stream, tributary or aquifer for application to beneficial use.

appropriation: Placement of a specified portion of the waters of the state to a beneficial use pursuant to the procedures prescribed by law. Speculation is prohibited. The appropriator must have its own use for the water or have a contract to serve the customers that the water will benefit. Only previously unappropriated surface or tributary goundwater can be appropriated. The appropriator must have a plan to divert; store; or otherwise capture, possess and control the water for beneficial use.

Aquatic guidelines: Specific levels of water quality which, if reached, may adversely affect aquatic life. These are non-enforceable guidelines issued by a governmental agency or other institution.

Aquatic-life criteria: Water-quality guidelines for protection of aquatic life. Often refers to U.S. Environmental Protection Agency water-quality criteria for protection of aquatic organisms. See also Water-quality guidelines, Water-quality criteria, and Freshwater chronic criteria.
aquatic guidelines: Specific levels of water quality which, if reached, may adversely affect aquatic life. These are non-enforceable guidelines issued by a governmental agency or other institution.

aquifer: An underground deposit of sand, gravel or rock through which water can pass or is stored. Aquifers supply the water for wells and springs.

artificial recharge: Augmentation of natural replenishment of ground-water storage by some method of construction, spreading of water, or by pumping water directly into an aquifer.

atmospheric deposition: The transfer of substances from the air to the surface of the Earth, either in wet form (rain, fog, snow, dew, frost, hail) or in dry form (gases, aerosols, particles).

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 preventing injury to the water rights of senior users.

augmentation source: The supply of water used to replace out-of-priority depletions.

Back to Top


Background concentration: A concentration of a substance in a particular environment that is indicative of minimal influence by human (anthropogenic) sources.

bank: The sloping ground that borders a stream and confines the water in the natural channel when the water level, or flow, is normal.

base flow: Sustained, low flow in a stream; ground-water discharge is the source of base flow in most places.

basic fixed sites: Sites on streams at which stream flow is measured and samples are collected for temperature, salinity, suspended sediment, major ions and metal, nutrients, and organic carbon to assess the broad-scale spatial and temporal character and transport of inorganic constituents of stream water in relation to hydrologic conditions and environmental settings.

basin: See drainage basin.

basin and range physiography: A region characterized by a series of generally north-trending mountain ranges separated by alluvial valleys.

bed load: Sediment that moves on or near the streambed and is in almost continuous contact with the bed.

bedrock: General term for consolidated (solid) rock that underlies soils or other unconsolidated material.

Bed sediment: The material that temporarily is stationary in the bottom of a stream or other watercourse.

beneficial use: Beneficial use is the basis, measure and limit of a water right. Colorado law broadly defines beneficial use of water as a lawful appropriation that uses reasonably efficient practices to put water to use without waste.

Best management practice (BMP): An agricultural practice that has been determined to a an effective practical means of preventing or reducing non point source pollution.

Bioaccumulation: The biological sequestering of a substance at a higher concentration than that at which it occurs in the surrounding environment or medium. Also, the process whereby a substance enters organisms through the gills, epithelial tissues, dietary, or other sources.

Bioavailability: The capacity of a chemical constituent to be taken up by living organisms either through physical contact or by ingestion.

biomass: The amount of living matter, in the form of organisms, present in a particular habitat, usually expressed as weight per unit area.

biota: Living organisms.

Blue-baby syndrome: methemoglobinemia, A condition that can be caused by ingestion of high amounts of nitrate resulting in the blood losing its ability to effectively carry oxygen. It is most common in young infants and certain elderly people.

Breakdown product: A compound derived by chemical, biological, or physical action upon a pesticide. The breakdown is a natural process which may result in a more toxic or a less toxic compound and a more persistent or less persistent compound.

Bureau of Land Management (BLM): Federal agency within the U. S. Department of Interior that manages most public lands in Colorado that are not national forest.

Bureau of Reclamation (USBR/BOR/BurRec.): Federal water development agency within the U.S. Department of Interior.

bypass Flow: Water that is allowed to flow past a diversion structure or storage facility.

Back to Top


call: Demand for administration of water rights. In times of water shortage, the owner of a decreed water right will make a “call” for water. The call results in shut down orders against undecreed water uses and decreed junior water rights as necessary to fill the beneficial use need of the decreed senior calling right.

canopy angle: Generally, a measure of the openness of a stream to sunlight. Specifically, the angle formed by an imaginary line from the the highest structure (for example: tree, shrub, or bluff) on one bank to eye level at mid-channel to the highest structure on the other bank.

carbonate rocks: Rocks (such as limestone or dolostone) that are composed primarily of minerals (such as calcite and dolomite) containing the carbonate ion.

center pivot irrigation: An automated sprinkler system involving a rotating pipe or boom that supplies water to a circular area of an agricultural field through sprinkler heads or nozzles.

channelization: Modification of a stream, typically by straightening the channel, to provide more uniform flow; often done for flood control or for improved agricultural drainage or irrigation.

Chlordane: Octachloro-4,7-methanotetrahydroindane. An organochlorine insecticde no longer registered for us in the U.S. Technical chlordane is a mixture in which the primary components are cis- and trans-chlordane, cis- and trans-nonachlor, and heptachlor.

Chlorinated solvent – A volatile organic compound containing chlorine.  Some common solvents are trichloroethylene, tetrachloroethylene, and carbon tetrachloride.

Chlorofluorocarbons – A class of volatile compounds consisting of carbon, chlorine, and fluorine.  Commonly called freons, which have been used in refrigeration mechanisms, as blowing agents in the fabrication of flexible and rigid foams, and , until several years ago, as propellants in spray cans.

clastic: Rock or sediment composed principally of broken fragments that are derived from preexisting rocks which have been transported from their place of origin, as in sandstone.

Clean Water Act: The federal 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 surface waters from both point and non-point sources of pollution.

climate: The sum total of the meteorological elements that characterize the average and extreme conditions of the atmosphere over a long period of time at any one place or region of the Earth’s surface.

Colorado Department of Natural Resources (DNR): State department with overall responsibility for water resources development and administration.

Colorado Department of Public Health and Environment (CDPHE): State department with overall responsibility for water quality, including drinking water and wastewater.

Colorado Revised Statutes (C.R.S.) The annual compilation of Colorado statutes and court rules published by the Colorado General Assembly.

Colorado Doctrine: see appropriation.

Colorado Water Conservation Board: The state agency vested with the authority to appropriate water of streams and lakes in amounts that are determined to be necessary to preserve the natural environment to a reasonable degree.

Colorado Water and Power Development Authority (CWPDA): State agency created to fund water developement, including water projects, drinking water treatment plants, and wastewater treatment plants.

combined sewer overflow: A discharge of untreated sewerage and storm water to a stream when the capacity of a combined storm/sanitary sewer system is exceeded by storm runoff.

community: In ecology, the species that interact in a common area.

compact: An agreement between two or more states approved by their state legislatures and the U.S. Congress. Compacts are akin to treaties between states. A water compact is a contract between two or more states setting the terms for sharing the waters of an interstate stream.

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.

concentration: The amount or mass of a substance present in a given volume or mass of sample. Usually expressed as microgram per liter (water sample) or micrograms per kilogram (sediment or tissue sample).

conditional water right: The legal preservation of a priority date that provides a water user time to develop his or her water right, but reserves a more senior date. A conditional right becomes an absolute right when water is actually put to beneficial use.

Confined aquifer (artesian aquifer): An aquifer that is completely filled with water under pressure and that is overlain by material that restricts the movement of water.

Confining layer: A layer of sediment or lithologic unit of low permeability that bounds an aquifer.

confluence: The flowing together of two or more streams; the place where a tributary joins the main stream.

conjuctive 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.”

Conservancy district: Established by decree of a court under the Water Conservancy District Act of 1937. A conservancy district can obtain rights-of-way for works; contract with the United States or otherwise provide for construction of facilities; assume contractual or bonded indebtedness; administer, operate, and maintain physical works; have authority to conserve, control, allocate, and distribute water supplies; and have contracting and limited taxing authority to derive the revenues necessary to accomplish its purposes. There are currently 45 conservancy districts in Colorado.

conservation: Obtaining the benefits of water more efficiently, resulting in reduced demand for water. Sometimes called “end-use efficiency” or “demand management.”

conservation district: Established under specific statues by the Colorado General Assembly. There are currently three conservation districts in Colorado; the Colorado River Water Conservation District, the Southwestern Water Conservation District, and the Rio Grande Water Conservation District. The mission is to oversee the conservation, use, and development of water in large geographical areas of the state.

constituent: A chemical or biological substance in water, sediment, or biota that can be measured by an analytical method.

consumptive use: Water use that permanently withdraws water from its source and is no longer available because it has evaporated, been transpired by plants, incorporated into products or crops, consumed by people or livestock, or otherwise removed from the immediate water environment.

contamination: Degradation of water quality compared to original or natural conditions due to human activity.

Continental Divide: An imaginary boundary line that runs north-south along the crest of the Rocky Mountains, separating river and drainages that flow west to the Pacific Ocean from those that flow south and east toward the Gulf of Mexico and the Atlantic Ocean.

contributing area: The area in a drainage basin that contributes water to streamflow or recharge to an aquifer.

criterion: A standard rule or test on which a judgement or decision can be based.

cubic feet per second (cfs): Measurement of flow rate of water in a running stream or taken as direct diversion from the stream. Water flowing at 1 cubic feet per second will deliver 448.8 gallons per minute or 648,000 gallons per day or approximately 2 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.

Back to Top


decree: A court decision about a water right that is then administered by Colorado’s Water Resources Department.

degradation products: Compounds resulting from transformation of an organic substance through chemical, photochemical, and/or biochemical reactions.

deligence: Reasonable progress toward making a conditional water right absolute by putting unappropriated water to a beneficial use. Must be proved in a water court proceeding through an application initiated every six years after entry of the conditional decree or most recent diligence decree. Acts demonstrating diligence include engineering, permitting, financing, and construction of water facilities needed to complete water diversion and delivery to the place of use.

denitrification: A process by which oxidized forms of nitrogen such as nitrate are reduced to form nitrites, nitrogen oxides, ammonia, or free nitrogen: commonly brought about by the action of denitrifying bacteria and usually resulting in the escape of nitrogen to the air.

designated ground water: Ground water which in its natural course would not be available to and required for the fulfillment of decreed surface rights, or ground water in areas not adjacent to a continuously flowing natural stream wherein ground water withdrawals have constituted the principal water usage for at least 15 years preceding the date of the first hearing on the proposed designation of the basin, and which in both cases is within the geographic boundaries of a designated ground water basin.

designated ground water basin: An area established by the Colorado Ground Water Commission as containing designated ground water, which is assumed not to affect the major surface river basin to which the designated basin would otherwise be tributary. Much of eastern Colorado is located within designated basins.

developed or imported water: Water brought into a stream system from another unconnected source, for example, transmountain diversion water or non-tributary well water. This type of water can be reused and successively used to extinction, and is often used in augmentation or exchange plans. In contrast, native basin water is subject to one use, and the return flow belongs to the stream system to fill other appropriations, unless a decree was obtained for the right to reuse and successively use return flows.

detect: To determine the presence of a compound.

direct flow (also 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.

discharge: Rate of fluid flow passing a given point at a given moment in time, expressed as volume per unit of time.

dissolved constituent: Operationally defined as a constituent that passes through a 0.45 micrometer filter.

dissolved solids: Amount of minerals, such as salt, that are dissolved in water; amount of dissolved solids is an indicator or salinity of hardness.

diversion or divert: Removing water from its natural course or location, or controlling water in its natural course or location, by means of a water structure such as a canal, flume, ditch pipeline, pump, reservoir, conduit, or well. The Colorado Water Conservation Board may appropriate instream flows without diversion, and local governmental agencies may make recreational in-channel diversions, under specified statutory procedures.

division engineer: Official appointed by the State Engineer to administer water rights within one of the state’s seven water divisions, which generally correspond to major river basins.

drainage area: The drainage area of a stream at a specified location is that area, measured in a horizontal plane, which is enclosed by a drainage divide.

drainage basin: The portion of the surface of the Earth that contributes water to a stream through overland run-off, including tributaries and impoundments.

drawdown: The difference between the water level in a well before pumping and the water level in the well during pumping. Also, for flowing wells, the reduction of the pressure head as a result of the discharge of water.

drinking water standard or guideline: A threshold concentration in a public drinking-water supply, designed to protect human health. As defined here, standards are U.S. Environmental Protection Agency regulations that specify the maximum contamination levels for public water systems required to protect the public welfare; guidelines have no regulatory status and are issued in an advisory capacity.

drip irrigation: An irrigation system in which water is applied directly to the root zone of plants by means of applicators (orifices, emmitters, porous tubing, perforated pipe, and so forth) operated under low pressure. The applicators can be placed on or below the surface of the ground or can suspended from supports.

drought: A long period of below-average precipitation.

due diligence: The efforts necessary to complete a water appropriation action that demonstrates a good faith action to complete a diversion of water within a reasonable time period.

duty of water: The amount of water that through careful management and use, without wasteage, 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.

Back to Top


ecological studies: Studies of biological communities and habitat characteristics to evaluate the effects of physical and chemical characteristics of water and hydrologic conditions on aquatic biota and to determine how biological and habitat characteristics differ among environmental settings.

ecoregion: An area of similar climate, landform, soil, potential natural vegetation, hydrology, or other ecologically relevant variables.

ecosystem: The interacting populations of plants, animals, and microorganisms occupying an area, plus their physical environment.

effluent: Outflow from a particular source, such as a stream that flows from a lake or liquid waste that flows from a factory or sewage-treatment plant.

effluent limits: Limitations on the concentration and/or mass of specific pollutants that a facility is allowed to discharge.

effluent exchange: The practice of using wastewater effluent from transbasin water, non-tributary water sources, or other sources without causing injury to other water rights as a replacement source of water for diversion of water farther upstream that would otherwise have been out of priority.

Endangered Species Act: The federal law that governs how animal and plant species whose populations are dangerously in decline or close to extinction will be protected and recovered. The law protects not only threatened and endangered species, but also the ecosystems upon which they depend.

Energy Policy Act (EPACT): A 1992 federal law that states, among other things, that no toilet for household use manufactured after Jan. 1, 1994, shall use more than 1.6 gallons per flush and that shower heads and faucets manufactured after Jan. 1, 1994, may not use more than 2.5 gallons per minute.

Environmental framework: Natural and human-related features of the land and hydrologic system, such as geology, land use, and habitat, that provide a unifying framework for make comparative assessments of the factors that govern water-quality conditions within and among Study Units.

environmental sample: A water sample collected from an aquifer or stream for the purpose of chemical, physical, or biological characterization of the sampled resource.

environmental setting: Land area characterized by a unique combination of natural and human-related factors such as row crop cultivation or glacial-till soils.

ephemeral stream: A stream or part of a stream that flows only in direct response to precipitation or snowmelt.

equal-width increment (EWI) sample: A composite sample across a section of stream with equal spacing between verticals and equal transit rates within each vertical that yields a representative sample of stream conditions.

equitable apportionment: A division of the waters of an interstate stream between two or more states made either by the U.S. Supreme Court or the U.S. Congress.

erosion: The process whereby materials of the Earth’s crust are loosened, dissolved, or worn away and simultaneously moved from one place to another.

eutrophication: The process by which water becomes enriched with plant nutrients, most commonly phosphorus and nitrogen.

evaporite minerals (deposits): Minerals or deposits of minerals formed by evaporation of water containing salts. These deposits are common in arid climates.

Evaportranspiration: A collective term that includes water lost through evaporation from the soil and surface-water bodies and by plant transpiration.

exchange: A process by which water, under certain conditions, may be diverted out of priority at one point by replacing it with a like amount of water at another point.

exempt wells: those wells that are exempt from water rights administration under a priority system (examples of exempt wells are household use only, domestic and livestock wells, and pre 1972 unregistered wells).

Back to Top


FDA action level: A regulatory level recommended by the U.S. Environmental Protection Agency for enforcement by the FDA when pesticide residues occur in food commodities for reasons other than the direct application of the pesticide. Action levels are set for inadvertent pesticide residues resulting from previous legal use or accidental contamination. Applies to edible portions of fish and shellfish in interstate commerce.

fertilizer: Any of a large number of natural or synthetic materials, including manure and nitrogen, phosphorus, and potassium compounds, spread on or worked into soil to increase its fertility.

firm annual yield: The yearly amount of water that can be dependably supplied from the raw water sources of a given water supply system.

flood: Any relatively high streamflow that overtops the natural or artificial banks of a stream.

flood irrigation: The application of irrigation water where the entire surface of the soil is covered by pond water.

flood plain: The relatively level area of land bordering a stream channel and inundated during moderate to severe floods.

flowpath: An underground route for ground-water movement, extending from a recharge (intake) zone to a discharge (output) zone such as a shallow stream.

flowpath study: Network of clustered wells located along a flowpath extending from a recharge zone to a discharge zone, preferably a shallow stream. The studies examine the relations of land-use practices, ground-water flow, and contaminant occurrence and transport. These studies are located in the area of one of the land-use studies.

fluvial deposit: A sedimentary deposit consisting of material transported by suspension or laid down by a river or stream.

freshwater chronic criteria: The highest concentration of a contaminant that freshwater aquatic organisms can be exposed to for an extended period of time (4 days) without adverse effects. See also Water -quality criteria.

furrow irrigation: A type of surface irrigation where water is applied at the upper end of a field and flows in furrows to the lower end.

futile call: Determination made by the state or division engineer to lift a shutdown order if cessation of diversions by junior decreed water rights will not result in making water available to the senior calling right.

Back to Top


Gaging station:A particular site on a stream, canal, lake, or reservoir where systematic observations of hydrologic data are obtained.

Geothermal: Relating to the Earth’s internal heat; commonly applied to springs or vents discharging hot water or steam.

ground water: Water located beneath the surface of the earth, typically withdrawn for use through wells.

Back to Top


Habitat:  The part of the physical environment where plants and animals live.

hardness: The sum of the concentration of calcium and magnesium expressed on a calcium carbonate basis.

headwaters: The small streams, generally in the mountains, that are the sources of a river; the first and smallest tributaries of a river.

Health advisory:  Non-regulatory levels of contaminants in drinking water that may be used as guidance in the absence of regulatory limits.  Advisories consist of estimates of concentrations that would result in no known or anticipated health effects (for carcinogens, a specified cancer risk) determined for a child or for an adult for various exposure periods.

Hydrograph:  Graph showing variation of water elevation, velocity, streamflow, or other property of water with respect to time.

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.

Back to Top


Infiltration: Movement of water, typically downward, into soil or porous rock.

injury: The action of another that causes or may cause the holders of decreed water rights to suffer loss of water at the time, place, and amount they would be entitled to use under their water rights if the actions had not occurred. Injury is a significant issue in any water court proceeding and in determinations of the State and Division Engineer.

Instantaneous discharge: The volume of water that passes a point at a particular instant of time.

Instream use: Water use taking place within the stream channel for such purposes as hydroelectric power generation, navigation, water-quality improvement, fish propagation, and recreation.  Sometimes call non withdrawal use or in channel use.

instream flows: Water flowing in its natural stream bed, such as water required for maintaining flowing streams, or for fish.

Integrator or Mixed-used site: Stream sampling site located at an outlet of a drainage basin that contains multiple environmental settings.  Most integrator sites are on major streams with relatively large drainage areas.

Intensive Fixed Sites: Basic Fixed Sties with increased sampling frequency during selected seasonal periods and analysis of dissolved pesticides for 1 year.  Most NAWQA Study Units have one to two integrator intensive fixed sites and one to four indicator intensive fixed sites.

Intermittent stream: A stream that flows only when it receives water from rainfall runoff or springs, or from some surface source such as melting snow.

interstate compacts: see compacts

Irrigation return flow: The part of irrigation applied to the surface that is not consumed by evaportranspiration or uptake by plants and that migrates to an aquifer or surface-water body.

Back to Top


junior rights: Water rights that are more recently and therefore are junior in priority to older or more senior rights.

Back to Top


Karst: A type of topography that results from dissolution and collapse of carbonate rocks such as limestone and dolomite, and characterized by closed depressions or sinkholes, caves, and underground drainage.

Kill:  Dutch term for stream or creek.

Back to Top


Land-use study:  A network of existing shallow wells in an area having a relatively uniform land use. These studies are a subset of the Study-Unit Survey and have the goal of relating the quality of shallow ground water to land use.

Leaching: The removal of materials in solution from soil or rock to ground water; refers to movement of pesticides or nutrients from land surface to ground water.

Load:  General term that refers to a material or constituent in solution, in suspension, or in transport; usually expressed in terms of mass or volume.

Loess:  Homogeneous, fine-grained sediment made up primarily of silt and clay, and deposited over a wide area (probably by wind).

Long-term monitoring: Data collection over a period of years or decades to assess changes in selected hydrologic conditions.

Back to Top


Main stem:  The principal course of a river or a stream.

mean discharge (MEAN): The arithmetic mean of individual daily mean discharges during a specific period, usually daily, monthly, or annually.

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.

Monitoring: Repeated observation or sampling at a site, on a scheduled or event basis, for a particular purpose.

monitoring well: A well designed for measuring water levels and testing ground-water quality.

Mouth: The place where a stream discharges to a larger stream, a lake, or the sea.

Back to Top


National Pollution Discharge Elimination System (NPDES) Permit: A permit required under Section 401 of the Clean Water Act regulating discharge of pollutants to the nation’s waterways.

National Environmental Policy Act (NEPA): The federal law enacted in 1969 to ensure federal agencies consider environmental impacts in their decision making.

Nitrate: An ion consisting of nitrogen and oxygen (NO3). Nitrate is a plant nutrient and is very mobile in soils.

Noncontact water recreation:  Recreational activities, such as fishing or boating, that do not include direct contact with the water.

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-exempt wells: those that are governed by the priority system and may be curtailed (included any other type of well not considered exempt).

non-point source: A diffuse source of water pollution, such as general runoff over the land surface; a pollution source that does not meet the definition of a “point source”.

nonpoint source contaminant:  A substance that pollutes or degrades water that comes from lawn or cropland runoff, the atmosphere, rodeways, and other diffuse sources.

nonpoint-source water pollution: Water contamination that originates from a broad area (such as leaching of agricultural chemicals from crop land) and enters the water resource diffusely over a large area.

non-tributary ground water: Ground water outside of the boundaries of any designated ground water basin, the withdrawal of which will not, within 100 years, deplete the flow of a natural stream at an annual rate greater than one-one-tenth of a one percent of the annual rate of withdrawal.

Back to Top

Occurrence and distribution assessment:  Characterization of the broad-scale spatial and temporal distributions of water-quality conditions in relation to major contaminant sources and background conditions for surface water and ground water.

Outwash: Soil material washed down a hillside by rainwater and deposited upon more gently sloping land.

Overland flow:  The part of surface runoff flowing over land surfaces toward stream channels.

Back to Top

parshall flume: A specially shaped structure that can be installed in a channel to measure the water flow rate. The flume was developed by Ralph Parshall at Colorado State University early in the last century.

Perennial stream: A stream that normally has water in its channel at all times.

Pesticide: A chemical applied to crops, rights of way, lawns, or residences to control weeds, insects, fungi, nematodes, rodents or other “pests.”

pH: The logarithm of the reciperocal of the hydrogen ion concentration (activity) of a solution; a measure of the acidity (pH less than &) or alkalinity (pH greater than 7) of a solution;  a pH of 7 is neutral.

Phosphorus: A nutrient essential for growth that can play a key role in stimulating aquatic growth in lakes and streams.

Photosynthesis: Synthesis of chemical compounds by organisms with the aid of light.  Carbon dioxide is used as raw material for photosynthesis and oxygen is a product.

Phthalates: A class of organic compounds containing phthalic acid esters[(C6H4(COOR)2] and derivatives.  Used as plasticizers in plastics.  also, used in many other products (such as detergents, cosmetics) and industrial processes (such as defoaming agents during paper and paperboard manufacture, and dielectrics in capacitors).

Physiography: A description of the surface features of the Earth, with an emphasis on the origin of landforms.

point source: A pipe, channel, conduit, or other discrete conveyance from which pollutants are discharged of various types.

pollutant: Any waste or other contaminant that adversely affects water quality.

pollution: The man-made or man-induced alteration of the chemical, physical, biological, and radiological integrity of water.

Pool: A small part of the stream reach with little velocity, commonly with water deeper than surrounding areas.

potable: Water that does not contain pollution, contamination, objectionable minerals, or ineffective agents and is considered safe for domestic consumption; drinkable.

precipitation: Any or all forms of water particles that fall from the atmosphere, such as rain, snow, hail and sleet.

prior appropriation doctrine: 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.

priority: The ranking of a water right vise-a-vs all other water rights drawing on the surface stream and tributary ground water system. Priority is determined by the year in which the application for the water right was filed. The date the appropriation was initiated determines the regulartivepriority of water rights for which the applications were filed in the same year. Priority is the most valuable aspect of a water right because priorities determine who may divert and use water in time of short water supply.

priority date: The date of establishment of a water right. The rights established by application have the application date as the date of priority.

Public-supply withdrawals: Water withdrawn by public and private water suppliers for use within a general community.  Water is used for a variety of purposes such as domestic, commercial, industrial, and public water use.

Back to Top


Radon: A naturally occurring, colorless, odorless, radioactive gas formed by the disintegration of the element radium; damaging to human lungs when inhaled.

raw water: Untreated water.

reasonable 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.

recharge: Water that infiltrates the ground and reaches the saturated zone.

reservoir: A structure used to collect and store water, or a tank or cistern used to store potable water.

return flows: Water that returns to streams and rivers after it has been applied to beneficial use. It may return as a surface flow, or as an inflow of tributary ground water.

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.

revegetate: To provide barren land with a new vegetative cover.

reviewable waters: Colorado surface waters that have not been designated “outstanding water” or “use-protected,” and which are subject to an antidegradation review before new or increased contamination is allowed.

Riffle: A shallow part of the stream where water flows swiftly over completely or partially submerged obstructions to produce surface agitation.

riparian: Referring to land or habitat immediately adjacent to the stream channel.

riparian rights: Water rights that are acquired based on ownership of 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.

riparian water law: A legal system that permits water use only by those who own land along the banks of a stream or lake. The right is for reasonable use and is correlative with the right of every other property owner to prohibit unreasonable use that diminishes the instream quantity or quality of water. Colorado law does not recognize riparian rights.

runoff: Water that flows on the earth’s surface into streams, rivers, lakes, and oceans.

Back to Top


Safe Drinking Water Act (SDWA): Federal legislation that regulates the treatment of water for human consumption. Requires testing for and elimination of contaminants to levels for the protection of human health.

sediment: Particles, derived from rocks or biological materials, that have been transported by a fluid or other natural process, suspended or settle in water.

Sediment guideline:  Threshold concentration above which there is a high probability of adverse effects on aquatic life from sediment contamination, determined using modified USEPA (1996) procedures.

senior rights: Water rights that are staked the earliest with the water court.

Sinuosity:  The ratio of the channel length between two points on a channel to the straight-line distance between the same two points; a measure of meandering.

sole source aquifer: A ground water system that supplies at least 50 percent of the drinking water to a particular human population: the term is used to denote special protection requirements under the Safe Drinking Water Act and may be used by approval of the U.S. Environmental Protection Agency.

specific conductance A measure of the ability of a liquid to conduct an electrical current.

spill water: Water released from a reservoir because the reservoir lacks sufficient storage capacity.

State Engineer’s Office (SEO): Agency that administers water rights within the Division of Water Resources, Colorado Department of Natural Resources.

Stream-aquifer interactions:  Relations of water flow and chemistry between streams and aquifers that are hydraulically connected.

stream flow: A type of channel flow, applied to that part of surface runoff in a stream whether or not it is affected by diversion or regulation.

Stream mile:  A distance of 1 mile along a line connecting the midpoints of the channel of a stream.

Stream order:  A ranking of the relative sizes of streams within a watershed based on the nature of their tributaries.  The smallest unbranched tributary is called first order, the stream receiving the tributary is called second order, and so on.

Stream reach:  A continuous part of a stream between two specified points.

Study Unit: A major hydrologic system of the United States in which NAWQA studies are focused.  Study Units are geographically defined by a combination of ground- and surface-water features and generally encompass more than 4,000 square miles of land area.

Study-Unit Survey:  Broad assessment of the water-quality conditions of the major aquifer systems of each Study Unit.  The Study-Unit Survey relies primarily on sampling existing wells and, wherever possible, on existing data collected by other agencies and programs.  Typically, 20 to 30 wells are sampled in each of three to five aquifer subunits.

storage: Water held in a reservoir for later use.

stormwater runoff: Rainfall or snowmelt that runs off over the land surface, potentially carrying pollutants to streams, lakes, or reservoirs.

Subsidence:  Compression of soft aquifer materials in a confined aquifer due to pumping of water from the aquifer.

substitute supply plan: A State Engineer approved temporary plan of replacement supply allowing an out of priority diversion. The State Engineer may approve substitute water supply plans while a plan for augmentation is pending in water court, for water exchanges, water uses that will not exceed five years, and in limited emergency situations affecting public health or safety.

Substrate size:  The diameter of streambed particles such as clay, silt, sand, gravel, cobble and boulders.

subsurface drainage: A shallow drain installed in an irrigated filed to intercept the rising ground water level and maintain the water table at an acceptable depth below the land surface.

Suspended sediment:  Particles of rock, sand, soil, and organic detritus carried in suspension in the water column, in contrast to sediment that moves on or near the streambed.

surface water: An open body of water, such as a lake, river, or stream.

system loss: An amount of water, expressed as a percentage, lost from a water storage or distribution system due to leaks, evaporation, seepage and unauthorized use.

Back to Top


temporary modification: A temporary relaxation of numerical water quality standards, allowing time for actions to improve water quality and achieve a long term standard.

Tile drain: A buried perforated pipe designed to remove excess water from soils.

total maximum daily load (TMDL): A calculation of the total amount of pollutants that can be added to a water body from all sources while still meeting water quality standards.

transbasin diversion: The conveyance of water from its natural drainage basin into another basin for beneficial use.

transmountain diversion: The conveyance of water from one drainage basin to another across the Continental Divide.

treated water: Water that has been filtered and/or disinfected; sometimes used interchangeably with “potable” water.

tributary: A stream or river flowing into a larger river, stream or lake.

tributary drainage: The area from which water naturally drains by gravity into a water course.

tributary ground water: Water present below the earth’s surface that is hydrologically connected to a natural surface stream.

Tritium:  A radioactive form of hydrogen with atoms of three times the mass of ordinary hydrogen; used to determine the age of water.

Turbidity: Reduced clarity of surface water because of suspended particles, usually sediment.

Back to Top


Unconfined aquifer: An aquifer whose upper surface is a water table; an aquifer containing unconfined ground water.

Unconsolidated deposit:  Deposit of loosely bound sediment that typically fills topographically low areas.

Upgradient:  Of or pertaining to the places(s) from which ground water originated or traveled through before reaching a given point in an aquifer in an aquifer.

Upland:  Elevated land above low areas along a stream or between hills; elevated region from which rivers gather drainage.

urban runoff: Excess water that doesn’t infiltrate the soil, but flows to a storm sewer or open waterway.

use attainability analysis (UAA): A structured, scientific assessment of factors that may affect the ability to achieve a particular use of water. The analysis may consider physical, chemical, biological, and economic factors that affect whether a use can be attained.

use classification: A formal designation of the uses (aquatic life, recreation, water supply, and agriculture) for which the water quality in a stream, lake, or reservoir will be protected.

use protected waters: Water bodies that are not subject to antidegradation review, but rather are protected only for their classified uses.

Back to Top


Wasteway:  A waterway used to drain excess irrigation water dumped from the irrigation delivery system.

water bank: A pilot program operating under rules of the State Engineer in the Arkansas River Basin to facilitate the lease, exchange, or loan of legally stored water as an alternative to sale of water rights, while protecting against injury to other water rights.

Water budget:  An accounting of the inflow, outflow, and storage changes of water in a hydrologic unit.

Water column studies:  Investigations of physical and chemical characteristics of surface water, which include suspended sediment, dissolved solids, major ions, and metals, nutrients, organic carbon, and dissolved pesticides,d in relation to hydrologic conditions, sources, and transport.

water commissioner: Official appointed by the Division Engineer to administer water rights in a water district, which generally coincides with a significant watershed, sub-basin, or tributary.

Water Quality Control Commission (WQCC): Appointed board within the Colorado Department of Public Health and Environment that establishes rules and regulations for the protection of water quality within the state.

Water Quality Control Division (WQCD): State agency within the Colorado Department of Public Health and Environment that administers the state’s water quality and drinking water programs.

Water quality criteria: Specific levels of water quality which, if reached, are expected to render a body of water unsuitable for its designated use.  Commonly refers to water quality criteria established by the U.S. Environmental Protection Agency.  Water-quality criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.

Water quality guidelines:  Specific levels of water quality which, if reached, may adversely affect human health or aquatic life.  These are non-enforceable guidelines issued by a governmental agency or other institution.

Water quality standards:  State adopted and U.S. Environmental Protection Agency-approved ambient standards for water bodies.  Standards include the use of the water body and the water-quality criteria that must be met to protect the designated use or uses.

water and sanitation districts: A special taxing district formed by the residents of the district for the combined purpose of providing potable water and sanitary wastewater services.

Water table:  The point below the land surface where ground water is first encountered and below which the earth is saturated.  Depth to the water table varies widely across the country.

water right: A right to use, in accordance with its priority, a portion of the waters of the state by reason of the appropriation of the same.

waters of the state: All surface and underground water in or tributary to all natural streams within the state of Colorado, except for designated ground water.

watershed: An area from which water drains and contributes to a given point on a stream or river.

Water year:  The continuous 12 month period, October 1 through September 30, in U.S. Geological Survey reports dealing with the surface-water supply.  The water year is designated by the calendar year in which it ends and which includes 9 of the 12 months.  Thus, the year ending September 30, 1980, is referred to as the “1980” water year.

Weather:  The state of the atmosphere at any particular time and place.

well: Any structure or device used for the purpose or wit the effect of obtaining ground water for beneficial use from an aquifer. Ever well requires a State Engineer-issued permit.

Wellhead Protection Program: An amendment to the federal Safe Drinking Water Act in 1986. Initiated to minimize the potential for contamination of public ground water supplies.

wetlands: Areas near the margin between water and land (such as swamps and marshes) that are wet enough to support plant growth typically found in saturated soil conditions.

Withdrawal:  The act or process of removing; such as removing water from a stream for irrigation or public water supply.

Back to Top


Yield:  The mass of material or constituent transported by a river in a specified period of time divided by the drainage area of the river basin.

Back to Top


Xeriscape: A landscape concept to describe beautiful landscaping that has low water needs. The term was developed by Denver Water in 1981. It is derived from the Greek word xeros, meaning dry.

Back to Top

Leave a Reply

Your email address will not be published. Required fields are marked *