Acre-foot: The volume of water required to cover one acre to a depth of one foot. Equal to 43,560 cubic feet or 325,851 gallons, or 1,233 cubic meters.
 
Adjudication: Judicial process to determine the extent and priority of the rights of persons to use water in a river or aquifer system.
 
Alluvial aquifer: An aquifer formed by material laid down by physical processes in a stream channel or on a floodplain.
 
Alluvium: Unconsolidated clay, silt, sand, or gravel deposited during recent geologic time by running water in the bed of a stream or on its floodplain.
 
Appropriation: The right to use water for a beneficial use or the acquisition of such a right gained through the process of diverting water and putting it to a beneficial use.
 
Appropriative rights: Appropriative water rights, generally found in western states, are created by diversion of water and putting it to beneficial use. Appropriative water rights have a priority based on the date of first usage. In times of shortage, junior appropriators are cut off while senior appropriators receive their full allotment.
 
Aquifer: A saturated water-bearing formation, or group of formations, which yield water in sufficient quantity to be of consequence as a source of supply.
 
Aquifer system: Heterogeneous body of interbedded permeable and poorly permeable material that functions regionally as a water-yielding unit. It consists of two or more permeable beds separated at least locally by confining beds that impede vertical groundwater movement, but do not greatly affect the regional hydraulic continuity of the system; includes both saturated and unsaturated parts of permeable materials.
 
Aquifer yield: Maximum rate of withdrawal that can be sustained by an aquifer. See Yield.
 
Artesian well or artesian spring: A well or spring that taps groundwater under pressure beneath an aquiclude so that water rises (though not necessarily to the surface) without pumping. If the water rises above the surface, it is known as a flowing artesian well.
 
Artificial recharge: Deliberate act of adding water to a groundwater aquifer by means of a recharge project. Artificial recharge can be accomplished via injection wells, spreading basins, or in-stream projects.
 
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.
 
Basin yield: Maximum rate of withdrawal that can be sustained by the complete hydrogeologic system in a basin without causing unacceptable declines in hydraulic head anywhere in the system or causing unacceptable changes to any other component of the hydrologic cycle in the basin. See Yield.
 
Bed: A layer of rock in the earth. Also the bottom of a body of water such as a river, lake, or sea.
 
Bedrock: The solid rock that underlies any unconsolidated sediment or soil. Shale and granites are common types of bedrock in Colorado.
 
Beneficial use: Use of water, such as domestic, municipal, agricultural, mining, industrial, stock watering, recreation, wildlife, artificial recharge, power generation, or contamination remediation, that provides a benefit. Water rights not put to beneficial use are subject to forfeiture. Historically, very few uses of water have been declared non-beneficial by courts.
 
Capture:  Water withdrawn artificially from an aquifer derived from a decrease in storage in the aquifer, a reduction in the previous discharge from the aquifer, an increase in the recharge, or a combination of these changes. The decrease in discharge plus the increase in recharge is termed capture. Capture results in reduced surface flows.
 
Certification: The process whereby a permit to appropriate water is finalized based on the completion of the diversion work and past application of water to the proposed use in accordance with the approved water-right application. A certified water right has a legal, state-issued document that establishes a priority date, type of beneficial use, and the maximum amount of water that can be used annually.
 
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 water (oceans, lakes, streams and rivers, groundwater, and wetlands). The law provides protection for the country’s water for both point and non-point sources of pollution.
 
Colorado Water Quality Control Act: Legislation to prevent injury to beneficial uses made of state waters, to maximize the beneficial uses of water, and to achieve the maximum practical degree of water quality in Colorado.
 
Commercial water use: Water for motels, hotels, restaurants, office buildings, other commercial facilities, and institutions. The water may be obtained from a public supply or may be self-supplied.
 
Community water system: A public system that serves a year-round residential population such as a group of homes receiving water from the same source.
 
Conditional water right: Legal preservation of a priority date that provides a water user time to develop a water right while reserving a more senior date. A conditional water right becomes an absolute right water is actually put to beneficial use.
 
Cone of depression:  A cone-shaped depression in the water table around a well or a group of wells. The cone is created by withdrawing groundwater more quickly than it can be replaced.
 
Confined aquifer: An aquifer that is bounded above and below by confining layers. Because of the pressure created in a confined aquifer, the water level in a well drilled into a confined aquifer will rise above the top of the aquifer and, in some instances, above the land’s surface.
 
Conjunctive use: Coordinated use of surface and groundwater supplies to meet demand so that both sources are used more efficiently.
 
Conservation: Management of water resources to eliminate waste or maximize efficiency of use.
 
Conservation storage: Storage of water in a reservoir for later release for useful purposes such as municipal and industrial water supply, water quality, or irrigation.
 
Consumptive use: That portion of water withdrawn from and lost to the immediate surface or groundwater storage environment. Typical withdrawals or uses included evaporation, transpiration, incorporation into products or crops, consumption by humans or livestock, or other removals.

Contaminant: A substance not naturally occurring in water or occurring in an amount that presents a health risk.

Cubic foot per second (cfs): Rate of discharge representing a volume of cubic foot (28.317 x 10-3 m3) passing a given point during one second. This rate is equivalent to approximately 7.48 gallons (0.0283 m3) per second.

Decree: An official document issued by the court defining the priority, amount, use, and location of water right (see Adjudication).

Depletion: Use of water in a manner that makes it no longer available to other users in the same system.

Depletion time: Time indicating how long it would take the watershed or the ground0water system to dry out if surface runoff or ground0water replenishment (recharge) were stopped from an instant onward, and if outflow water maintained at the rate it had at that instant. Depletion times of surficial waters usually are on the order of hours to weeks. They may run into month or years if the river basin includes large lakes. Depletion times of aquifers are usually on the order of tens to hundreds, and often thousands of years. As a consequence, rivers react quickly to precipitation and to abstraction of water, whereas groundwater systems react very sluggishly to these events.

Depth to water: The depth of the water table below the Earth’s surface.

Designated basin: An area in which the use of groundwater 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.

Development permit: An application to use, alter, construct upon, or otherwise change the use of land, including rezoning, special exception use, building, clearing, grading, or other approval that allows the alteration of land or a structure.

Discharge: The volume of water passing a particular point in a unit of time. Units of discharge commonly used include cubic feet per second (cfs) or gallons per minute (gpm).

Disinfection by-products: Chemicals, such as total trihalomethanes, formed from naturally occurring humic or fulvic acids and the disinfectant used to treating water.

Diversion: Physical removal of surface water from a channel. Also, the act of bringing water under control by means of a well, pump, or other device for delivery and distribution for a proposed use.

Domestic well use: Water used for drinking and other purposes by a household, such as from a rural well. Domestic use permits allow limited irrigation and outside watering uses.

Drainage basin: Hydrologic unit consisting of a part of the surface of the earth covered by a drainage system made up of a surface stream of body of impounded surface water plus all tributaries. The runoff in a drainage basin is distinct from that of adjacent areas. A river basin is similarly defined.

Effluent: Any substance, particularly a liquid, that enters the environment from a point source. Generally, refers to waste- water from a sewage-treatment or industrial plant.

Evaporation: Process of liquid water becoming water vapor, including vaporization from water surfaces, land surfaces, and snowfields, but not through leaf surfaces. Compare with transpiration.

Evapotranspiration: A collective term for water that moves.

Flow: The volume of water moving past a point during a specified time. Also known as discharge.

Freshwater: Water containing only small quantities (generally less than 1,000 milligrams per liter) of dissolved materials.

Goal: Brief, clear statement of an outcome to be reached.

Gravel pack: Coarse sand and gravel placed in the annular space between the borehole and the well casing in the vicinity of the well screen. The purpose of the gravel pack is to minimize the entry of fine sediment into the well, stabilize the borehole, and allow the flow of groundwater into the well.

Groundwater: Underground water that is generally found in the pore space of rocks or sediments and that can be collected with wells, tunnels, or drainage galleries, or that flows naturally to the Earth’s surface via seeps or springs.

Groundwater basin: Geologically and hydrologically defined area that contains one or more aquifers that store and transmit water and will yield significant quantities of water to wells.

Groundwater mining: Pumping groundwater from a basin at a rate that exceeds safe yield, thereby extracting groundwater that had accumulated over a long period of time.

Groundwater storage: 1) Quantity of water in the saturated zone, or 2) water available only from the storage as opposed to capture.

Hydraulic head of (static) head: Height that water in an aquifer can raise itself above an arbitrary reference level (or datum), generally measured in feet or meters. When a borehole is drilled into an aquifer, the level at which the water stands in the borehole (measured with reference to a horizontal datum such as sea level) is, for most purposes, the hydraulic head of water in the aquifer at that location. Groundwater possesses energy mainly by virtue of its elevation (elevation head) and of its pressure (pressure head). When groundwater moves, some energy is dissipated and therefore a head loss occurs.

Hydraulically connected: A condition in which groundwater moves easily between aquifers that are in direct contact. An indication of this condition is that the water levels in both aquifers are approximately equal.

Hydrologic budget or balance: Accounting of the inflow to, outflow from, and storage in a hydrologic unit such as a drainage basin, aquifer, soil zone, lake, or reservoir; the relationship between evaporation, precipitation, runoff, and the change in water storage, expressed by the hydrologic equation.

Hydrologic cycle: The complete cycle that water can pass through, beginning as atmospheric water vapor, turning into precipitation and falling to the earth’s surface, moving into aquifers or surface water, and then returning to the atmosphere via evapotranspiration.

Hydrology: The study of the characteristics and occurrence of water, and the hydrologic cycle. Hydrology concerns the science of surface water and groundwater, whereas hydrogeology principally focuses on groundwater.

Hydrostatic pressure: The pressure exerted by the water at any given point in a body of water or aquifer.

Impervious: Resistant to penetration by water or plant root.

Industrial uses: Water used for a wide range of purposes by industries, including cooling water for electrical power generation, manufacturing, food preparation, washing of wastes, etc. The quality needed ranges substantially depending on the use.

Infiltration (soil): Movement of water from the ground surface into the soil.

Injection well: Well used for injecting water or other fluid into a groundwater aquifer. See Artificial recharge.

Inorganic: Not made of or derived from living matter. Minerals are inorganic.

Instream use: Use of water that does not require withdrawal or diversion from its natural watercourse; for example, the use of water for navigation, recreation, and support of fish and wildlife.

Intermittent flow: Surface water flowing only during periods of seasonal runoff.

Irrigation use: Water applied to the soil surface by center pivots, ditches, or other means or to the soil subsurface by tubes to add to the water available for plant growth.

Livestock water use: Water for livestock watering, feed lots, dairy operations, fish farming, and other on-farm needs. Livestock as used here includes cattle, sheep, goats, hogs, and poultry.

Master plan: A plan and any functional element to the plan as adopted and amended, for the physical development of the unincorporated territory of the County. Also known as the El Paso County Comprehensive Plan, El Paso County Master Plan, the Master Plan for El Paso County, and the El Paso County Land Use Plan.

Monitoring well: Non-pumping well used primarily for taking water-quality samples and measuring groundwater levels. See Observation well.

Nonconsumptive use: Use that leaves the water available for other uses. Examples are hydroelectric power generation and recreational uses.
Non-potable: Water not suitable for drinking.

Nontributary groundwater: Underground water in an aquifer that neither draws from nor contributes to a natural surface stream in any measurable degree.

Not-nontributary groundwater: Ground water located within those portions of the Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers that are outside of any designated ground water basin in existence on January 1, 1985, the withdrawal of which will, within 100 years, deplete the flow of a natural stream at an annual rate greater than one-tenth of one percent of the annual rate of withdrawal.

Objective: Specific, measurable, realistic, and timebound condition that must be attained in order to accomplish a particular goal. Objectives define the actions must be taken within a year to reach the strategic goals.
 
Observation well: Non-pumping well used primarily for observing the elevation of the water table or the piezometric pressure; also to obtain water-quality samples.
 
Organic: Pertaining to or relating to a compound containing carbon. For example, petroleum products contain organic compounds derived from plant and animal remains.
 
Percolation: Laminar-gravity flow through unsaturated and saturated earth material.
 
Permeability: 1) Ability of a material (generally an earth material) to transmit fluids (water) through its pores when subjected to pressure of a difference in head. Expressed in units of volume of fluid (water) per unit time per cross section area of material for a given hydraulic head; 2) description of the ease with which a fluid may move through a porous medium; abbreviation of intrinsic permeability. It is a property of the porous medium only, in contrast to hydraulic conductivity, which is a property of both the porous medium and the fluid content of the medium.
 
Point source: Source of pollution that originates from a single point, such as an outflow pipe from a factory.
 
Policy: Deliberate system of principles to guide decisions and achieve rational outcomes.
 
Pollution: Contamination from human activities that restricts the uses of water.
 
Porosity: Fraction of bulk volume of a material consisting of pore space. Porosity determines the capacity of a rock formation to absorb and store groundwater.
 
Porous: Geologically, this term describes rock that permits movement of fluids through small, often microscopic openings, much as water moving through a sponge. Porous rocks may contain gas, oil, or water.
 
Precipitation: Water in some form that falls from the atmosphere. It can be in the form of liquid (rain or drizzle) or solid (snow, hail, sleet).
 
Prior appropriation: Doctrine for prioritizing water rights based upon dates of appropriation (“first in time, first in right”). Common method for allocating water rights in the western United States.
 
Priority: Seniority date of a water right or conditional water right to determine their relative standing to other mater rights and conditional water rights and conditional water rights deriving water from a common source. Priority is a function of both the appropriation date and the relevant adjudication date to the right.
 
Priority date: The date a water right is established.
 
Raw water: Untreated water.
 
Recharge: The replenishment of groundwater in an aquifer. It can be either natural, through the movement of precipitation into an aquifer, or artificial in the pumping of water into an aquifer.
 
Recharge area: A geographic area where water enters (recharges) an aquifer. Recharge areas usually coincide with topographically elevated regions where aquifer units crop out at the surface. In these areas infiltrated precipitation is the primary source of recharge. The recharge area also may coincide with the area of hydraulic connection where one aquifer receives flow from another adjacent aquifer.

Reclaimed wastewater: Wastewater treatment plant effluent that has been diverted for beneficial use before it reaches a natural waterway or aquifer.

Recycled water: Water that is used more than one time before it passes back into the natural hydrologic system.

Return flow: Part of water that is not consumed and returns to its source or another body of water.

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.

Saturated thickness: The vertical thickness of an aquifer that is full of water. The upper surface is the water table. The height of the hydrogeologically defined aquifer unit in which the pore spaces are filled (saturated) with water. For the High Plains aquifer and similar unconfined, unconsolidated aquifers, the saturated thickness is equal to the difference in elevation between the base of the aquifer and the water table. The predevelopment saturated thickness is based on the best available estimate of the elevation of the water table prior to human altercation by groundwater pumping.

Saturated zone: A subsurface zone in which all the interstices are filled with water under pressure greater than atmospheric. The upper surface of the saturation zone is the water table.

Specific storage: Volume of water released from or taken into storage per unit volume of the porous medium per unit change in head. It is the three-dimensional equivalent of storage coefficient or storativity, and is equal to storativity divided by aquifer saturated thickness.

State Engineer: The person charged by state law with the supervision and administration of water and the enforcement of decreed priority and legislative enactments. The State Engineer discharges the obligations of the state of Colorado imposed by compact or judicial orders and coordinates the work of the Division of Water Resources with other departments of state government. The State Engineer has rule-making obligations and supervisory control over measurements, record keeping, and distribution of the public water of the state and all employees under his direction and any other such acts as may be reasonable necessary to enable the performance of his duties.

Strategy: The art of devising or employing plans or stratagems toward a goal.

Static level: Refers to the level of water in a well under normal, undisturbed, no-pumping conditions. Static level is best determined when the well has not been pumped for several hours prior to measuring. You may get a false reading if the well was pumped just before the static level is measured.

Streamflow: Discharge that occurs in a natural channel. A more general term than runoff, streamflow may be applied to discharge whether or not it is affected by diversion or regulation.

Surface water: Water found at the Earth’s surface, usually in streams or lakes.

Sustainability: Meets the needs of the present without compromising the ability of future generations to meet their own needs.

Transmissivity: Flow capacity of an aquifer measured in volume per unit time per unit width. Equal to the product of hydraulic conductivity times the saturated thickness of the aquifer.

Treated water: Water that has been filtered and disinfected.

Tributary: A tributary is generally regarded as a surface water drainage system which is interconnected with a river system. Under Colorado law, all surface and groundwater, the withdrawals of which would affect the rate or direction of flow of a surface stream within 100 years, is considered to be tributary to a natural stream.

Unconfined aquifer: An aquifer that is not bounded above by a confining bed; water levels in wells screened in an unconfined aquifer coincide with the elevation of the water table.

Unsaturated zone: Also known as the vadose zone, this is the area of soil or rock just above the water table.

Void: Pore space or other openings in rock. The openings can be very small to cave-size and are filled with water below the water table.

Wastewater: Water that carries wastes from homes, businesses, and industries.

Water court: A specific district court that has exclusive jurisdiction to hear and adjudicate water matters. There are seven water courts in Colorado, a judge, who is also district court judge, presides over each court.

Water level: The level of water in a well or aquifer. It can be measured as depth below the ground surface or as an elevation related to a datum, such as sea level.

Water quality: Physical, chemical, and biological characteristics of water and how they relate to it for a particular use.

Water Quality Control Act: Colorado statute enacted in 1981 to protect, maintain, and improve the quality of state waters through prevention, abatement, and control of water pollution. This act created the nine member Water Quality Control Commission that is responsible for developing specific water quality policy.

Water right: Any vested or appropriation right under which a person may lawfully divert and use water. It is a real property right appurtenant to and severable from the land on or in connection with which the water is used. Water rights pass as an appurtenance with a conveyance of the land by deed, lease, mortgage, will, or inheritance.

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

Water table: A fluctuating demarcation line between the unsaturated (vadose) zone and the saturated (phreatic) zone that forms an aquifer. It may rise or fall depending on precipitation (rainfall) trends. The water table is semi-parallel to the land surface above but is not always a consistent straight line. Because of impervious beds of shale, etc., local water tables can be perched above the area’s average water table.

Water year: Twelve-month period in which the U.S. Geological Survey reports surface water supplies. Water years begin October 1 and end the following September 30, and are designated by the calendar year in which the water year ends.

Well: A vertical excavation into an underground rock formation.

Well permit: The granting of permission by the State Engineer allowing the digging of a hole in search of groundwater to apply to a beneficial use. A written permit obtained from the State giving permission to dig a hole to find groundwater.

Well yield: Pumping rate that can be supplied by a well without drawing the water level in the well below the pump intake. See Yield.
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Yield: Amount of water that can be supplied from a reservoir, aquifer, basin, or other system during a specified interval of time. This time period may vary from a day to several years depending upon the size of the system involved.