Acre-Foot – a measurement of water. It is the amount of water that will cover an acre of land (slightly smaller than a football field) at a depth of one foot, or 325,851 gallons. An acre-foot typically serves the needs for a family of four for a year.

Allocation – the amount of pumping allotted to each contract annually.

Alluvium – a general term for clay, silt, sand, gravel, etc. deposited by a stream or other body of water.

Annual Assessments – fees paid by well users to CCWCD subdistricts to allow them to pump wells out-of-priority and have Central manage the augmentation plan, purchase water rights and leases and build projects and infrastructure.

Appropriation – the right to take water from a stream or aquifer for beneficial use, at a specific rate or flow. Water courts must issue a decree for the appropriated water.

Aquifer – a water-bearing layer of rock or sediment capable of yielding supplies of water.

Augmentation – Method used to allow wells to pump out-of-priority without injuring senior water rights downstream. Augmentation plans must be court approved.

Basin – the drainage area of a river or lake.

Basin Roundtables – Nine separate basin roundtables were established by the Colorado Water for the 21st Century Act for each of the state’s eight major river basins and the Denver metropolitan area. These basin roundtables facilitate discussions on water issues and encourage locally driven collaborative solutions.

Call – the right of a senior water rights holder to “call” for his water. Junior water rights holders must pass the water on to the senior holder and not divert until the right is satisfied. Administered by the Division of Water Resources.

Change of Use – legal requirement that water rights be changed from agriculture to augmentation (or other) uses.

Colorado Water Congress (CWC) – water-lobbying organization located in Denver.

Colorado Water Conservation Board (CWCB) – represents each major water basin in a joint effort to use water wisely and protect water for future generations.

Consumptive Use – that portion of a water right totally consumed by a crop or other vegetation.

Cubic Feet Per Second (CFS) – a rate of flow for water in a moving stream or diversion. Water flowing at 1cfs will deliver 448.8 gallons per minute.

Designated Basin – an area in which it has been determined that use of groundwater does not impact the surface river basin to which a designated basin would otherwise be tributary. Much of eastern Colorado is in designated basins.

Diversion – Removing water from its natural course or location by means of a water structure such as ditch, pipeline, flume, reservoir, bypass, well or other device.

Effluent and Influent – water leaving a reservoir or process, such as a water or wastewater treatment plant. Influent is the water entering a reservoir or process.

ET (Evapotranspiration) – the process by which water is transmitted as a vapor to the atmosphere as the result of evaporation from any surface and transpiration from plants.

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 location downstream.

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.

GIS (Geographic Information System) – a computerized mapping system.

IBCC (Interbasin Compact Committee) – The Interbasin Compact Committee (IBCC) was established by the Colorado Water for the 21st Century Act to facilitate conversations among Colorado’s river basins and to address statewide water issues. Composed of 27 members.

Instream Flow – water flowing in a natural stream bed; water required for maintaining stream flow or for fish.

Integrated Decision Support Consumptive Use (IDSCU) – an efficient model for computing field & farm consumptive use.

Interruptible Water Leasing – authorized by state statute in 2003, a method by which farmers are allowed to lease water to cities during drought emergencies.

Irrigation Allotment Contracts – legal documents used to provide augmentation to member wells. Also known as Class B, C and D contracts.

Leaching – the downward transport by percolating water of minerals into a soil.

MOU (Memorandum of Understanding) – Document signed between government entities to formally state a position or plan of action.

Nontributary Groundwater – groundwater outside of the boundaries of any designated groundwater basin, the withdrawal of which will not, within one hundred 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.

Not Nontributary Groundwater – Denver Basin groundwater, the withdrawal of which will deplete the flow of a natural stream at an annual rate of greater than one-tenth of one percent of the annual rate of withdrawal.

NWRA (National Water Resources Association) – National water lobbying organization located in Washington, DC.

Priority – the ranking of a water right in relation to all other water rights drawing on the same stream system. Priority is determined by the year in which the application for the water right was filed.

Prior Appropriation – the water law doctrine that confers priority to use water from natural streams based upon when the water rights were acquired. Also referred to as “First in time, first in right”.

Quota – defines the percentage of well usage on each member contract. This amount is determined annually by the Board of Directors.

Recharge – the process of adding water to an aquifer by injection or infiltration. Dug basins, injection wells, or the simple spreading of water across a land surface all are means of artificial recharge.

Return Flow – water that returns to streams and rivers after it has been applied to beneficial use. It may return as a surface flow, or as in in-flow of tributary groundwater.

Riparian – referring to land or habitat immediately adjacent to the stream channel.

SPWRAP (South Platte Water Related Activities Program) – an organization created to help expedite the process of obtaining permits.

Substitute Supply Plan – a State Engineer approved temporary plan of replacement supply allowing an out-of-priority diversion while a plan for augmentation is proceeding through the water court.

Three-States-Agreement – documents signed by the governors of Nebraska, Wyoming, and Colorado to use a basin-wide approach to protect endangered species in central Nebraska.

Transmissivity – a measure of the ability of an aquifer to transmit water.

Tributary Groundwater – all subsurface water hydraulically connected to a surface stream, the pumping of which would have a measurable effect on the surface stream within one hundred years.

Water Right – a property right to the use of a portion of the public’s surface or tributary groundwater resource obtained under applicable legal procedures.

Glossary Definitions taken from the Denver Water Community Relations publication “Denver Water Glossary of Frequently Used Water Terms”, published 2001 and the Colorado Foundation for Water Education’s Citizen Guide “Colorado Water Law”, 2nd edition, published 2004.

A more comprehensive glossary can be found at: The Groundwater Foundation