arabinoseA five-carbon sugar - C5H1005. A product of hydrolysis of arabinan found in the hemicellulose fraction of biomass.
Arable landsRefers to all lands generally under rotation whether it is under temporary crops, temporarily fallowed, or used as temporary meadows.
Archaeological siteAny location where humans have altered the terrain or discarded artifacts during prehistoric or historic times.
Arctic tundraA treeless area between the icecap and the tree line of Arctic regions that has permanently frozen subsoil and supports low-growing vegetation such as…
Area of Potential Effect (APE)The geographic area or areas within which an undertaking (project, activity, program, or practice) may cause changes in the character or use of any…
Area sources (emissions)Any source of air pollution that is released over a relatively small area but which cannot be classified as a point source.
Areas of Critical Environmental Concern (ACEC)These areas are managed by the Bureau of Land Management and are defined by the Federal Land Policy and Management Act of 1976 as having significant…
AridA region that receives too little water to support agriculture without irrigation. Less than ten inches of rainfall a year is typically considered arid.
Arizona Water Banking Authority (AWBA)The AWBA was established in 1996 to increase utilization of the state's Colorado River entitlement and to develop long-term storage credits for the state.
aromatic(A-ruh-MA-tik) Having an odor, which often is pleasant or spicy.
ArroyoA Spanish word for brook that refers to a dry river, creek, or stream bed that temporarily or seasonally fills and flows after sufficient rain.
Artesian water (artesian pressure)Groundwater that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered.
ArtifactAn object produced or shaped by human beings and of archaeological or historical interest.
AshThe non-combustible residue of a combusted substance composed primarily of alkali and metal oxides.
AtlatlA wood or bone shaft implement, held in one hand, and used to throw a spear. The tool functions as a lever, giving greater thrust and distance.
AtmosphereThe gaseous envelope surrounding the Earth, which consists almost entirely of nitrogen (78.1% volume mixing ratio) and oxygen (20.
Atmospheric absorptionAttenuation of sound during its passage through air, during which its sound energy is gradually converted into heat by a number of molecular processes in…
AttainmentAn area considered to have air quality as good as or better than the National Ambient Air Quality Standards for a given pollutant.
Attainment areaA geographic region where the concentration of a specific air pollutant does not exceed federal standards.
AttenuationA mechanism for controlling gene expression in prokaryotes that involves premature termination of transcription.
AugerA rotating, screw-type device that moves material through a cylinder. In alcohol production, it is used to transfer grains from storage to the grinding…
Augmentation PlanA court-approved plan that allows a junior water user to divert water out of priority so long as adequate replacement is made to the affected stream…
Augmentation waterWater used for the replacement of out of priority depletions.
Average Annual Daily Traffic (AADT)A measurement representing the total number of vehicles passing a given location, based upon 24-hour counts taken over an entire year.
Average megawatt (MWa, aMW)One megawatt of capacity produced continuously over a period of one year. 1 aMW = 1 MW x 8760 hours/year = 8,760 MWh = 8,760,000 kWh.
Avoided costsAn investment guideline describing the value of a conservation or generation resource investment by the cost of more expensive resources that a utility…