Glossary of Frequently Used Water Terms

Terms used in the water industry are often not employed in everyday conversation. With this in mind, a handy reference such as this might be useful for those who wish to gain a better understanding of the nomenclature.

Abandonment: Nonuse and the demonstrated intent to legally give up the right to use water for any purpose.
Acre Foot: A volume of water equal to one foot in depth covering an one acre; approximately 325,851 gallons. Roughly two-thirds of an acre foot serves the needs of a typical family of four for a year.
Adjudicate: To determine rights by a lawsuit in court.
Alluvial Water: Groundwater that is hydrologically part of a natural surface stream system.
Appropriate (or appropriation): To take the legal actions necessary to create a right to take water from a natural stream or aquifer and put it to 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.
Aquifer: An underground layer of sand, gravel or rock through which water can pass and is stored. Aquifers supply water for wells and spring.
Artesian: Groundwater, well or an underground basin in which water is under pressure greater than atmospheric and will rise above the level of its upper confining surface if given the opportunity to do so.
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 others.
Basin: The drainage or catchment area of a stream of lake.
Beneficial Use: Lawful and prudent use of water that has been diverted from a stream or aquifer for human or natural benefit.
Call: The exercise by an historically senior water right holder of “calling” for his water rights, requiring junior water right holders to allow water to pass to the senior right holder; a demand that upstream water rights with more recent (junior) priority dates than the calling right cease diverting.
Clean Water Act: The federal law that established how the United States will restore and maintain the chemical, physical and biological integrity of the country’s waters.
Colorado Doctrine: “First in time, first in right.” (see Prior Appropriation)
Colorado Water Conservation Board (CWCB): The state water policy board made up of appointed members authorized to appropriate water in streams and lakes in amounts determined necessary to preserve the natural environment to a reasonable degree. The CWCB also finances water projects and oversees statewide water conservation.
Compact: A contract between states and ratified by Congress that controls the division of water from a river or stream that flows across the states’ 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.
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 when water is actually put to beneficial use.
Consumptive Use: Any use of water that permanently removes it from a natural stream system.
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.
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.
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.
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.
Firm Annual Yield: The yearly amount of water that can be dependably supplied from the raw water sources of a given water supply system.
Free River: An occasion when there are no calls upon a river; any legal water rights holder can draw as much as decreed under that right.
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 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.
Instream Flow: Water flowing in a natural stream bed; water required for maintaining stream flow or for fish.
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 action had not occured. Injury is a significant issue in any water court proceeding and in determinations of the state and dicision engineers.
Junior Rights: Water rights that were obtained more recently and therefore are junior in priority to older or more senior rights.
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.
Nonconsumptive 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.
Nonpoint Source: The source of pollution discharged over a wide land area, not from one specific point, 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.
Nontributary Water: Underground water in an aquifer that neither draws from nor contributes to a natural surface stream in any measurable degree.
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 agens and is considered safe for human consumption; drinkable.
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 historically senior rights have first claim to withdraw water over holders who have filed later claims.
Priority: The right of a senior water rights holder to divert from a natural stream before a junior holder.
Priority Date: The date a water right is established.
Raw Water: Untreated water.
Reservoir: An impoundment to collect and store water. Raw water reservoirs impound water in a watershed; terminal reservoirs collect water where it leaves a watershed to enter the treatment process, and treated-water reservoirs are tanks or cisterns used to store potable water.
Return Flow: Water that returns to a stream after it has been used.
Riparian: Referring to land or haitat immediately adjacent to the stream channel.               
Runoff: Water that flow on the surface of the Earth into streams, rivers, lakes, and oceans.
Safety Factor: An amount of water added to demand projections to protect against unforeseen changes in water supply and demand.
Senior Rights: Water rights that are staked the earliest with the water court.
Tap: A physical connection made to a public water distribution system that provides service to an individual customer.
Trans-Basin Diversion: The conveyance of water from its natural basin or origin into another basin.
Treated Water: Water that has been filtered and disinfected. The term is sometimes used interchangeably with potable water.
Tributary: A stream or river that flow into a large one.
Wastewater: The used water and watereborne solids that flow to a wastewater treatment plant. Storm water, surface water and groundwater infiltration also may be included in wastewater that enters a plant.
Water Right: A property right to make beneficial use of a particular amount of water with a specified, historical priority date.
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.

For more water-related information contact the Water Information Program (WIP) at (970) 247-1302 or visit www.waterinfo.org.