Acre-foot (alternately, acre foot): One acre-foot is equivalent to approximately 325,851 gallons or about 1,233 cubic meters. This unit is often used to quantify water usage, especially in agricultural and water supply planning 

Adjudication: A legal process used to determine and allocate water rights among competing users or entities. Water adjudication is often employed in areas where water resources are scarce or multiple parties claim the same water source. 

Agricultural Conservation Easement Program (ACEP): A Natural Resources Conservation Service (NRCS) program that helps landowners, land trusts, and other entities protect, restore, and enhance wetlands or protect working farms and ranches through conservation easements. 

Agricultural Land Easement (ALE): A component of ACEP that helps private and tribal landowners, land trusts, and other entities such as state and local governments protect croplands and grasslands on working farms and ranches by limiting non-agricultural uses of the land through conservation easements. 

Aquifer: A permeable underground geological formation that stores and transmits water, often serving as a source of well water. 

Basin: A low-lying area on the Earth's surface in which water collects and drains into a common outlet, often forming a watershed. Examples include the Upper and Lower Colorado River basins, the Great Basin, the Rio Grande River Basin, and many others.  

Beneficial use: The appropriate and careful utilization of water diverted from a stream or aquifer to serve human or natural needs within the bounds of the law.  

Clean Water Act (CWA): The CWA establishes the basic structure for regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters. 

Consumptive use: Any utilization of water that permanently withdraws it from a natural stream system. 

Demand management: The concept of temporary, voluntary, and compensated reductions in the consumptive use of water 

Drought: A prolonged period of abnormally low precipitation, leading to water shortages and potentially impacting agriculture and ecosystems. 

Erosion: The process by which soil and rock are worn away by natural forces such as wind, water, or ice. 

Floodplain: The flat or nearly flat land adjacent to a river or stream that is subject to flooding during periods of high water. 

Groundwater: Water that is stored beneath the Earth's surface in soil and rock formations, often accessed through wells. 

Groundwater conservation easement: A new type of conservation easement that applies specifically to groundwater with the intention of compensating water users for keeping more water in the ground. 

Hydrology: The scientific study of water, including its distribution, movement, and properties in the atmosphere, on the Earth's surface, and underground. 

In-stream (alternately, instream) flow: Water coursing through a natural stream channel; water necessary to sustain the continuous flow of the stream or to support fish habitat. 

Irrigation: The artificial application of water to land to assist in the growth of crops, often through the use of canals, pipes, or other infrastructure. 

Junior water right: Water rights that were obtained more recently and therefore are junior in priority to older or more senior rights. 

Non-point source: The origin of pollution released across an extensive land area, not emanating from a singular point, which enters streams, lakes, and oceans. This includes runoff from streets, parking lots, lawns, agricultural land, individual septic systems, and construction sites. 

Overallocation: The condition in which the demand for water exceeds the available supply, leading to potential resource depletion. 

Point source: The origin of pollution released from any discernible point, encompassing ditches, channels, sewers, tunnels, and various types of containers. 

Prior appropriation, doctrine of: The water law principle granting priority to the utilization of water from natural streams according to the acquisition date of water rights. In Colorado and other western states, water rights are validated through court decrees, with those holding historically senior rights having precedence in withdrawing water compared to holders with later claims. 

Riparian: Describing land or habitat directly bordering the stream channel. 

Senior water right: Water rights that are filed first with the water court. 

Trans-basin diversion: The transfer of water from its natural basin or source to a different basin. 

Tributary: A smaller stream or river that flows into a larger one. 

Watershed: An area or ridge of land that separates waters flowing to different rivers, basins, or seas. 

Wetland reserve easement (WRE): A component of ACEP that helps private and tribal landowners protect, restore and enhance wetlands that have been previously degraded due to agricultural uses. 

Zeedyk structures: Zeedyk structures (named after habitat manager Bill Zeedyk) are manually constructed, low-profile interventions composed of rock or wood designed to rehabilitate the hydrological and ecological functions of wet meadows and small streams affected by issues such as head-cutting, gully erosion, and channel incision.