Pueblo rightsA water right possessed by a municipality which, as a successor of a Spanish or Mexican pueblo, entitled to the beneficial use of all needed…
Pulp chipsTimber or residues processed into small pieces of wood of more or less uniform dimensions with minimal amounts of bark.
Pyroclastic flowHigh-speed avalanches of hot ash, rock fragments, and gas that move down the sides of a volcano during explosive eruptions or when the steep edge of a…
Pyroclastic surgeSimilar to a pyroclastic flow, but contains a higher proportion of gas to rock and is more turbulent and faster moving.
PyrolysisThe transformation on a compound or material into one or more substances by heat alone (without oxidation). Often called destructive distillation.
Quad-level occurrenceThe recorded occurrence of a species in the area represented by a specific, named U.S. Geological Survey 7.5-minute topographic quadrangle map (quad map).
Qualifying FacilityA category of electric power producer established under the Public Utility Regulatory Policy Act (PURPA) of 1978, that includes small-power producers…
QuartziteA hard, metamorphic rock that was originally sandstone.
QuaternaryThe present period, forming the latter part of the Cenozoic Era, originating about 1 million years ago and including the Recent and Pleistocene epochs.
Rain shadow effectThe region on the lee (sheltered) side of a mountain or mountain range where the precipitation is noticeably less than on the windward side, because the…
RangelandLand on which the native vegetation, climax, or natural potential consists predominately of grasses, grasslike plants, forbs, or shrubs.
Rankine steam cycleThe thermodynamic cycle of temperature and pressure changes of water as it is converted from a liquid to a gaseous state by heating, and returns back to…
RAPTORA bird of prey such as a falcon, hawk, or eagle.
Rate ScheduleA mechanism used by electric utilities to determine prices for electricity; typically defines rates according to amounts of power demanded/consumed during…
Rated battery capacityThe term used by battery manufacturers to indicate the maximum amount of energy that can be withdrawn from a battery under specified discharge rate and…
reactionA chemical reaction is a dissociation, recombination, or rearrangement of atoms.
Rebound (of water levels)The recovery/rise of the water level in a groundwater aquifer after groundwater pumping has ceased.
ReceiverThe component of a central receiver solar thermal system where reflected solar energy is absorbed and converted to thermal energy.
receptor(reh-SEP-ter) A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific physiologic effect in the cell.
RechargeWater that infiltrates into the ground, usually from above, that replenishes groundwater reserves, provides soil moisture, and affords evapotranspiration.
RecirculationReturning a fraction of the effluent outflow to the inlet to dilute incoming wastewater.
ReclamationThe process of restoring surface environment to acceptable pre-existing conditions.
Reclamation withdrawalWithholding an area of public land from the operation of the public land laws for the purpose of reserving the land for the use of the Bureau of…
recombinant DNAThe process of cutting and recombining DNA fragments from different sources as a means to isolate genes or to alter their structure and function.
Record of Decision (ROD)(ROD)The Record of Decision (ROD) is a public document that explains which cleanup alternatives will be used to clean up a Superfund site.
Recovery boilerA pulp mill boiler in which lignin and spent cooking liquor (black liquor) is burned to generate steam.
ReflectorA component of a solar energy facility that reflects incident sunlight to a desired location or component within the facility, allowing it to be converted…
Reformulated gasoline (RFG)(RFG)Gasoline that has altered composition or characteristics to reduce emissions of pollutants from vehicles in accordance with the Clean Air Act.
Refractory LiningA lining, usually of ceramic, capable of resisting and maintaining high temperatures.
Refuse-Derived Fuel (RDF)(RDF)A solid fuel produced by shredding municipal solid waste (MSW). Noncombustible materials such as glass and metals are generally removed prior to making…
Regeneration harvestA timber harvest method that removes selected trees in the existing stand to a density that allows for the establishment of a new even-aged stand below.
Regeneration with reservesSimilar to a regeneration harvest, except that a number of green trees are left standing to meet other resource needs such as wildlife habitat.
Region of Influence (ROI)(ROI)Area occupied by affected resources and the distances at which impacts associated with license renewal may occur.
Regular-track proposalsProposals on public land with pending applications considered as potential future projects, but not necessarily foreseeable projects, since not all…
Reid vapor pressure (RVP)(RVP)A standard measurement of a liquid´s vapor pressure at 100 degrees Fahrenheit. An indication of the propensity of the liquid to evaporate.
ReinjectionThe feeding of unburned char and fly ash obtained from mechanical collectors into the furnace for further combustion.
RelictA land surface that was once a basin (valley) floor.
renewable energy resourceAn energy resource that can be replaced as it is used. Renewable energy resources include solar, wind, geothermal, hydro, and biomass.
Renewable energy sourceAn energy source that is replenished continuously in nature or that is replaced after use through natural means. Sustainable energy source.
Repetition/replicationThere are four plots in a repetition/replication, the early, mid and late seral treatment plots and a control plot.
ReptileCold-blooded vertebrate of the class Reptilia whose skin is usually covered in scales or scutes.
Reserve marginThe percentage of installed capacity exceeding the expected peak demand during a specified period.
Reserved Water RightA special water right accompanying federal lands (military reservations, national parks, forests, or monuments) or Indian reservations.
ReservoirA reservoir of an infectious agent, such as a virus, is any animal, person, plant, soil, substance—or combination of any of these — in which the…
Resident fishFish species that complete their entire life cycle in freshwater. Non-anadromous fish. An example is rainbow trout.
residues, biomassByproducts from processing all forms of biomass that have significant energy potential.
ResiduumUnconsolidated, weathered, or partly weathered mineral material that accumulates by disintegration of bedrock in place.
Resource Conservation and Recovery Act (RCRA)(RCRA)The primary goals of the Resource Conservation and Recovery Act (RCRA) are to protect human health and the environment from the potential hazards of waste…
Resource Management Plan (RMP)(RMP)A land use plan that establishes land use allocations, multiple use guidelines, and management objectives for a given planning area.
Resource valuesA resource, natural or social, that is found in an area. Resource values may have varying levels of significance.
Retinal damageDamage to photoreceptor cells of the retina. One mechanism for such damage is exposure to bright light that triggers chemical reactions in the tissues…
RetrofittingThe application of conservation, efficiency, or renewable energy technologies to existing structures.
Return on investment (ROI)(ROI)The interest rate at which the net present value of a project is zero. Multiple values are possible.
ReuseThe reclamation of water diverted from a municipal or industrial wastewater conveyance system.
RhyoliteVolcanic rock (or lava), characteristically light in color and containing 69% silica or more and generally rich in potassium and sodium (felsic…
Richter Magnitude ScaleDeveloped in 1935 by Charles Richter to measure and compare the size of earthquakes.
RiftAn area where the Earth's crust and lithosphere is being pulled apart by extensional tectonic forces.
Rift zoneA tectonic feature characterized by a central linear downfaulted segment (graben) with parallel normal faulting and flanking uplifts (horsts).
Right-of-way (ROW)(ROW)The legal right to cross the lands of another. Also used to indicate the strip of land for a road, railroad, or power line.
RillA small and shallow incision into topsoil layers resulting from erosion by overland flow or surface runoff that is common on slopes of unvegetated ground…
RinsateWater that is used to rinse or clean equipment or reaction vessels and that may, as a result, become contaminated and require special handling and…
RiparianRelating to, living in, or located on the bank of a river, lake, or tidewater.
Riparian AreaVegetated ecosystems along a waterbody through which energy, materials, and water pass.
Riparian bufferRiparian areas that are managed to protect the aquatic and riparian ecosystem. A riparian buffer protects water quality and temperature, habitat along the…
RiskThe possibility of loss; the uncertainty of future returns.
River BasinThe land area surrounding one river from its headwaters to its mouth. The area drained by a river and its tributaries.
Riverine wetlandWetlands within river and stream channels, generally characterized by flowing water. Ocean-derived salinity is less than 0.5 part per thousand.
Rock artImages on rock surfaces. There are two types of rock art: pictographs, which are drawn or painted onto the surface, and petroglyphs, which are pecked…
Rock outcropThe part of a rock formation that appears above the surface of the surrounding land.
RoostAn area where birds or bats rest or sleep. Birds often use branches or tree cavities for roosts while bats use tree bark, tree hollows, caves, mines…
RotationThe number of years allotted to establish and grow a forest stand to maturity.
Rough treesLive trees of commercial species which do not contain a sawlog because of roughness, poor form, splits, or cracks.
RoundwoodLogs, bolts, or other round sections cut from trees.
saccharideA simple sugar or a more complex compound that can be hydrolyzed to simple sugar units.
saccharificationA conversion process using acids, bases, or enzymes in which long-chain carbohydrates are broken down into their component fermentable sugars.
Sacred landscapesNatural places recognized by a cultural group as having spiritual or religious significance.
Sacred siteAny specific, discrete, narrowly delineated location on federal land that is identified by an Indian tribe, or Indian individual determined to be an…
Safe Drinking Water Act (SWDA)(SWDA)Act authorizing development of maximum contaminant levels for drinking water applicable to public water systems (i.e.
Safe yieldThe amount of groundwater that can be withdrawn from a groundwater basin over a period of time without exceeding the long-term recharge of the basin or…
SalinityA measure of the amount of salt and other mineral substances dissolved in water.
Salt flatLow-lying ground where salts collect in the soil because of the evaporation of standing water.
Salvage loggingThe harvest of dead, dying, damaged or weak trees after a forest fire to prevent the spread of disease or insects and to reduce the risk of high intensity…
SandA rock or mineral fragment of any composition that has a diameter ranging from 0.5 to 2.0 mm. Sand has a gritty feel.
Sand boilA sand boil is sand and water that come out onto the ground surface during an earthquake as a result of liquefaction at shallow depth.
Sand duneAn elongated mound (hill or ridge) of sand accumulated and sorted by the action of wind or water.
Sanitary wasteNonhazardous, nonradioactive liquid and solid waste generated by normal housekeeping activities.
Sanitary wastewaterWastewater (includes toilet, sink, shower, and kitchen flows) generated by normal housekeeping activities.
Saturated steamSteam at the temperature that corresponds to its boiling temperature at the same pressure.
SavannaA flat grassland of tropical and subtropical regions usually having distinct periods of dry and wet weather.
SawlogA log meeting minimum commercial requirements of diameter, length, and defect. The usual commercial requirements are a minimum of 8´ long with an inside…
SawtimberLive trees of commercial species containing at least one 12´ sawlog or two noncontiguous 8´ logs.
Scaled saleA type of timber sale contract that specifies measuring or scaling of the included timber after removal.
ScarifyLoosening topsoil or breaking up the forest floor to improve conditions for seed germination or tree planting.