Day-night average noise levelTwenty-four-hour average noise level, obtained after the addition of a 10-dB penalty for environmental noise occurring from 10 p.m. to 7 a.m.
Daytime mean rural background levelDaytime (7 a.m. to 10 p.m.) average sound level in the rural environment, from all sources other than a particular noise that is of interest.
Debris flowA mixture of water-saturated rock debris that flows downslope under the force of gravity (also called lahar or mudflow).
Debris flow fansAlluvial fans prone to debris flows; a mixture of water and debris, such as mudslides, mudflows, or debris avalanches.
Decibel (dB)A standard unit for measuring the loudness or intensity of sound. In general, a sound doubles in loudness with every increase of 10 decibels.
Decibel, A-weighted (dBA)A measurement of sound approximating the sensitivity of the human ear and used to characterize the intensity or loudness of a sound.
DeciduousPlants that shed their leaves annually. Not evergreen.
Decision noticeThe written record of a federal agency decision after an environmental assessment.
DecommissioningThe process of removing a power plant, apparatus, equipment, building, or facility from operation.
DecouplingA regulatory design that breaks the link between utility revenues and energy sales to encourage utility investment in conservation.
Deep-cycle batteryA battery with large plates that can withstand many discharges to a low state of charge.
dehydrationA condition caused by the loss of too much water from the body. Severe diarrhea or vomiting can cause dehydration.
dehydrogenationA chemical reaction in which hydrogen is removed from a compound.
DeltaThe relationship between an option's price and the price of the underlying stock or futures contract is called its delta.
Demand-side managementSpecific actions taken by utility companies, their regulators, and other entities to induce, influence, or compel consumers to reduce their energy…
DemographicRelated to the vital statistics of human populations (size, density, growth, distribution, etc.) and the effect of these on social and economic conditions.
denaturantA substance that makes ethanol unfit for consumption.
DenaturedEthanol that has had a substance added to make it unfit for human consumption.
DensificationA mechanical process to compress biomass (usually wood waste) into pellets, briquettes, cubes, or densified logs.
DepletionNet loss of water through consumption, export, and other uses to a given area, river system, or basin.
DepositAn amount of money paid to the court. Hennepin County Housing Court can only accept cash and certified checks; personal checks, third-party checks, and…
DesertArid region receiving less than 10 inches of precipitation annually.
Desert benchA relatively flat terrace elevated above the surface of a desert alluvial feature, such as an ephemeral stream or wash.
Desert duneA wind-created ridge or mound of sand that is found in deserts or near oceans and lakes.
Desert focal bird speciesBird species whose requirements define spatial attributes, habitat characteristics, and management regimes representative of a healthy desert system.
Desert pavementA surface layer of closely packed, loosely cemented pebbles. See also Pediment
Desert riparian habitatHabitats characterized as dense groves of low shrublike trees, or tall shrubs to woodlands of small to medium-sized trees.
Desert scrubThe desert scrub community is characterized by plants adapted to seasonally dry climate.
Desert varnishThe thin red to black coating found on exposed rock surfaces in arid regions. Varnish is composed of clay minerals, oxides, and hydroxides of manganese…
Desert washA usually dry desert streambed that flows only after periods of heavy rain.
DesiccationThe process of removing moisture; involves evaporation.
Design basisThe set of conditions, dimensions, needs, and requirements used to design a solar energy facility.
Design featuresMeasures or procedures incorporated into the proposed action or alternatives which could avoid or reduce adverse impacts.
Designated Roads and TrailsSpecific roads and trails identified by the agencies where some type of motorized vehicle use is appropriate and allowed, either seasonally or yearlong.
Desired future conditionA vision of the desired future state of a specific area. A description of land and resource conditions expected to result if management goals and…
DetritusLoose natural materials, such as rock fragments or organic particles, that result directly from disintegration of rocks or organisms.
DewateringThe separation of free water from the solids portion of spent mash, sludge, or whole stillage by screening, centrifuging, filter pressing, or other means.
DiagnosticAn item that is indicative of a particular time and/or cultural group.
Diesel engineA compression-ignition piston engine in which fuel is ignited by injecting it into air that has been heated (unlike a spark-ignition engine).
Differential compactionMay occur over a large area when the compaction of soil or deeper sediments occurs at different rates and degrees.
DigesterAn airtight vessel or enclosure in which bacteria decomposes biomass in water to produce biogas.
DioriteA coarse-grained intrusive (or plutonic) igneous rock, less mafic than gabbro, but more mafic than granite and granodiorite; the plutonic equivalent of…
DioxinA family of compounds, some of which are hazardous, that result from combustion of carbon materials.
DipThe angle that a planar geologic surface, for example, a fault, is inclined from the horizontal.
Direct current (DC)A steady current that flows in one direction only. The current from batteries is an example of direct current.
Direct effectsEffects on the environment which occur at the same time and place as the initial cause or action.
Direct impactsImpacts occurring at the place of origin and at the time of the proposed activity.
Direct Normal Insolation (DNI)Sunlight that directly strikes a surface. DNI does not include refracted sunlight that strikes clouds, dust, or the ground first.
Directional drillingThe practice of drilling non-vertical wells. Also called slant drilling.
disaccharidesThe class of compound sugars that yields two monosaccharide units upon hydrolysis; examples are sucrose, maltose, and lactose.
Discharge(DIS-charj) In medicine, a fluid that comes out of the body. Discharge can be normal or a sign of disease.
Discount rateThe discount rate is the interest rate the Federal Reserve charges on loans it makes to banks and other financial institutions.
DiscountingA method of financial and economic analysis used to determine present and future values of investments or expenses.
Dish engineThe dish engine is a concentrating solar power (CSP) technology that produces electricity, typically in the range of 3 to 25 kilowatts, by using a…
Dispatchable power (dispatchability)The ability of a power-producing facility to provide required amounts of power (at or below the facility's nameplate rating) on demand of the grid…
DisposalA term used in some countries, including the U.S., to mean that an application has been abandoned, denied (rejected) or allowed (granted).
Distance zonesA subdivision of the landscape as viewed from an observer position. The BLM defined zones include foreground, middleground, background, and seldom seen.
distillateThe portion of a liquid that is removed as vapor and condensed during a distillation process.
Distillate oilAny distilled product of crude oil. A light petroleum product used for home heating and most machinery.
distillationThe process of heating a mixture to separate the more volatile from the less volatile parts, and then condensing fractions of the resulting vapour so as…
distillers dried grains (DDG)The dried grain byproduct of the grain fermentation process, which may be used as a high-protein animal feed.
Distillers´ dried grains (DDG)The dried byproduct of the grain fermentation process. Typically used as a high-protein animal feed.
Distributed GenerationA term used by the power industry to describe localized or on-site power generation.
DistributionThe sale of securities. Also refers to a sum payable to shareholders representing their share of profits.
District heating or coolingA system that involves the central production of hot water, steam, or chilled water and the distribution of these transfer media to heat or cool buildings.
DiversionThe process of removing some minor criminal, traffic or juvenile cases from the full judicial process, on the condition that the accused undergo some sort…
DiversityThe distribution and abundance of different plants and animals within an area.
Domestic water useWater used for household purposes such as drinking; food preparation; bathing; washing clothes, dishes, and dogs; flushing toilets; and watering lawns and…
Downdraft gasifierA gasifier in which the product gases pass through a combustion zone at the bottom of the gasifier.
Draft environmental impact statement (DEIS)A draft statement of environmental effects. Section 102 of the National Environmental Policy Act requires a DEIS for all major federal actions.
Dry cooling systemAlso known as dry closed-loop cooling; a technology for rejecting heat from the steam condensate of a thermoelectric plant.
Dry lakeAn ephemeral lake of an arid or semiarid region, typically found at low elevation points in desert valleys.
Dry Ton2,000 pounds of material dried to a constant weight.
Dry washA natural drainage channel that is typically dry, but conveys water following significant rainfall events and is subject to rapid flow during flash…
dryingMoisture removal from biomass to improve serviceability and utility.