Abiotic – Nonliving.

Acid deposition – The falling of human-produced acid from the atmosphere via all forms of precipitation.

Acid mine drainage – Drainage of water from areas that have been mined for coal or other mineral ores. Because of its contact with sulfur-bearing material, the water may have a very low pH and be harmful to aquatic organisms.

Acid rain – precipitation (rain, snow, sleet, etc.) that is more acidic than normal.

Acid soil – soil with an acid reaction and a pH below 6.6

Adaptation – A trait that contributes to the reproductive success of an individual organism.

Advanced wastewater treatment – Any treatment of sewage that goes beyond the secondary or biological water treatment stage and includes the removal of nutrients such as phosphorus and nitrogen and a high percentage of suspended solids.

Aeration – exposing water to the air; often results in the release into the atmosphere of gaseous impurities found in polluted water.

Aerobic – Refers to life or a process occurring only in the presence of free oxygen.

Agricultural Pollution – Farming wastes, including runoff and leaching of pesticides and fertilizers; erosion and dust from plowing; improper disposal of animal manure.

Agriculture – the cultivation or raising of plant crops and livestock.

Aggregate – Rock composed of fragments of several kinds of rock.

Air Pollution Control Act (1965) – A federal act establishing national standards for stationary and mobile exhausts to be sources of our pollution.

Algae – Microscopic plants which contain chlorophyll and live floating or suspended in water. They also may be attached to structures, rocks or other submerged surfaces. They are food for fish and small aquatic animals. Excess algal growths can impart tastes and odors to potable water. Algae produce oxygen during sunlight hours and use oxygen during the night hours. Their biological activities appreciably affect the pH and dissolved oxygen of the water.

Alkaline – the opposite of acidic; basic.

Alluvial soil – Soil that developed from transported and relatively recently deposited material, characterized by little or no modification of the original material by soil-forming processes.

Alluvium – Sediments, usually fine materials, deposited on land by a stream.

Anadromous – Fish that migrate to rivers from the sea for breeding.

Anaerobic – Refers to life or activity in the absence of free oxygen.

Antidegradation – Part of federal water quality requirements. Calls for all existing uses to be protected, for deterioration to be avoided or at least minimized when water quality meets or exceeds standards, and for outstanding waters to be strictly protected.

Appalachian Plateau – Westernmost physiographic province of the Appalachian Mountains, located west of the Allegheny Front, characterized by mild deformation.

Aquaculture – refers to aquatic organism farming in general and sometimes to freshwater organism farming in particular.

Aquifer – a relatively permeable rock layer below the water table that contains a significant amount of water.

Assessed waters – Waters that States, Tribes, and other jurisdictions have assessed according to physical, chemical, and biological parameters to determine whether or not the waters meet water quality standards and support designated beneficial uses.

Atmosphere – the sphere or “layer” of gases that surrounds the Earth.

Assimilative capacity – The capacity of a natural body of water to receive wastewaters or toxic materials without deleterious effects and without damage to aquatic life or humans who consume the water.


Bacteria – Microscopic living organisms that can aid in pollution control by metabolizing organic matter in sewage, oil spills or other pollutants. However, bacteria in soil, water or air can also cause human, animal and plant health problems.

Ballast water – Water carried by ocean going vessels. Ballast tanks may hold exotic species that are subsequently dumped into lakes causing the spread of exotic species.

Benthic – refers to the bottom-dwelling zone of the aquatic (specifically marine) biome.

Best Management Practices (BMP) – Methods that have been determined to be effective, practical means of preventing or reducing pollution from nonpoint sources.

Bioaccumulation – The retention and concentration of a substance by an organism.

Bioconcentration (Biomagnification) – the tendency for a substance to accumulate in living tissue.

Biocriteria – A combination of numerical measures, such as the number and kind of benthic, or bottom-dwelling, insects living in a stream, that are part of a state’s water quality standards.

Biodiversity – Refers to the variety and variability among living organisms and the ecological complexes in which they occur.

Biological oxygen demand (BOD) – the amount of oxygen used by organisms in a particular stream, lake, or other body of water to carry out decomposition.

Biomass – the total weight of living tissue in a community.

Biome – A major terrestrial ecosystem occurring on a major regional or subcontinental level.Bald. A naturally treeless area surrounded by forest.

Bioremediation – the use of bacteria and other small organisms to clean up or reduce unwanted concentrations of certain substances; also known as biotreatment.

Biosphere – the sphere or “layer” of living organisms on Earth.

Biotic – Living.

Bituminous Coal – Coal that yields pitch or tar when it is burned; soft coal.

Bottom sediments – Particles that settle to lake or bay floors. These particles often contain harmful chemicals, including toxic metals, that may contaminate aquatic wildlife.

Brownfields – Abandoned, idled or under-used industrial and commercial sites. Reuse of these sites may be complicated by real or perceived environmental contamination. Sites can be urban, suburban, or rural areas. Health risks in these areas can be reduced or eliminated and economic life can be restored.

Buffering – The modification of environmental conditions by vegetation or topographic features.

Buffer species – A plant or animal which may provide an alternative food for another animal and thus reduce the demand for certain food items.

Buffer strip – A strip of grassland or other erosion-resistant vegetation planted on the contour between or below cultivated strips or fields.

Buffer zone – an area of moderately utilized land that provides a transition into the unmodified natural habitat in the core preserve where no human disturbance is allowed.


Canopy – The nearly continuous layer of leaves along the top of a forest.

Carbon cycle – The circulation of carbon from carbon dioxide in the atmosphere into sugar by photosynthesis in plants, synthesis of more complex organic compounds in plants and animals, and the return by respiration or death and decay of plant and animal tissues to carbon dioxide.

Carrying capacity – the maximum population size that can be sustained by a certain environment for a long period of time; often represented by the symbol K.

Channelization – Straightening and deeping streams so water will move faster – a tactic that can interfere with waste assimilation capcity, disturb fish and wildlife habitats, and aggravate flooding.

Charismatic species – a high-profile endangered or threatened species that attracts broad public concern.

Chronic toxicity – The capacity of a substance to cause long-term poisonous health effects in humans, animals, fish and other organisms.

Clean Air Act – a federal statute enacted in 1963 that was the first of a series of acts and amendments that exerted increasing federal pressure on air polluters to clean up their emissions.

Clean Water Act (CWA) – a federal statute enacted in 1972 that has been very successful in improving the water quality of lakes and rivers.

Clear-cutting – the harvesting of trees such that an entire stand of trees is completely removed; also known as even-aged management.

Climate – the average weather in a certain area over time ranges of decades to millennia to hundreds of millions of years.

Closed-loop reclamation – treating wastewater to the level needed before direct reuse.

Closed system – An isolated system that exchanges nothing with other systems.

Combined sewer – A sewer system that carries both sewage and stormwater runoff.

Commensalisms – A form of symbiosis where one species benefits and the other is not affected.

Community – All of the populations of different species that inhabit a certain area.

Community succession – The sequential replacement of species in a community by immigration of new species and the local extinction of old species.

Competition – Organisms competing for the same limited resource.

Compliance monitoring – Collection and evaluation of data, including self-monitoring reports, and verification to show whether pollutant concentrations and loads contained in permitted discharges are in compliance with the limits and conditions specified in the permit.

Composting – The decomposition of organic materials by microorganisms; produces various forms of “soils.”

Concentrated animal feeding operation (CAFO) – large-scale poultry, hog or cattle operations that may create significant water quality problems.

Cone of depression – The localized lowering of the water table around a well from which water is being withdrawn faster than it is replenished.

Confined aquifer – An aquifer bounded above and below by aquicludes.

Conservation – Protection from loss, waste; the official care and protection of forests, rivers, etc.

Conservationism – The classical view that forests and other natural resources should be managed to provide the most benefit for the greatest number of people.

Consumed water – Water that is withdrawn and not returned to its original source.

Consumer – Organisms that feed on other organisms for their nutritional needs (heterotroph).

Contaminated water – Water that is rendered unusable for drinking.

Contamination – The introduction into water of microorganisms, chemicals, toxic substances, wastes, or wastewater in a concentration that makes the water unfit for its next intended use.

Contour – (1) An imaginary line on the surface of the land that connects points of the same altitude. (2) A line on a map to show the location of points of the same altitude.

Contour farming – The performance of farming operations such as plowing, seeding, and cultivating along contour lines.

Conventional pollutants – Statutorily listed pollutants understood well by scientists.

Creek – A stream that is intermediate between a river and a brook.

Creep – The slow, downward, mass movement of soil on a slope.

Criteria pollutants – With reference to air pollution, the five basic criteria pollutants are particulates, sulfur oxides, nitrogen oxides, volatile organic compounds, and carbon monoxide.

Cumulative exposure – The summation of exposures of an organism to a chemical over a period of time.


Dams – Structures that obstruct river or stream flow to form artificial lakes or reservoirs.

Dead zone – The area around a mine in which no vegetation or animal life can survive.

Deciduous – Having leaves that are shed in autumn.

Deep-well injection – A method of disposing of liquid wates, such as industrial or hazardous wastes, wherein they are pumped or injected down wells deep below the Earth’s surface.

Deficit areas – Areas that receive less precipitation than is needed by well-established vegetation.

Deforestation – The removal of forest cover from an area.

Dendritic drainage – Pattern of watercourses characterized by randomly branching tributaries.

Depression storage – Water temporarily detained on the surface of the Earth in puddles and cavities that have little or no surface outlet.

Depth diversity gradient – The concept that among aquatic communities species richness generally increases with water depth down to about 6560 feet and then declines with further depth.

Designated uses – Those water uses identified in state water quality standards that must be achieved and maintained as required under the Clean Water Act.

Detritus – Loose organic material resulting from breakdown of plant or animal bodies.

Dilution – The reduction in concentration of a pollutant when it is discharged into water.

Discharge – The volume of water carried by a channel.

Distillation – A method of desalination whereby salt water is evaporated so as to remove the dissolved salts.

Drainage basin – The region drained by a particular network of rivers and streams.

Dredging – Removal of mud from the bottom of water bodies.


Ecological community – Assemblage of populations of different organisms in a particular environment.

Ecological extinction – Occurs when a species, although not totally extinct in an area, has become so rare that it has essentially no role or impact on its ecosystem.

Ecological release – The population of a particular species increases greatly in size when a competitor is removed.

Ecological succession – The successive groups of plants and animals that will colonize a newly cleared patch of land or uncolonized body of water.

Ecology – The study of how organisms interact with each other and their environment.

Ecosystem – A biological community plus the surrounding physical environment.

Edge effects – Disturbances from the surrounding area penetrate along the edges of a preserved area, resulting in habitat loss.

Effluent – Wastewater, treated or untreated, that flows out of a treatment plant, sewer, or industrial outfall.

Endemic species – A very localized species that inhabits only a relatively small area.

Environment – All aspects of the natural environment plus human manipulations and additions to the natural environment.

Environmental Impact Statement (EIS) – A document required of federal agencies by the National Environmental Policy Act for major projects or legislative proposals significantly affecting the environment. A tool for decision making, it describes the positive and negative effects of the undertaking and cites alternative actions.

Environmental science – The systematic study of all aspects of the environment and their interactions.

Erosion – The detachment and movement of particles of the land surface by wind, water, ice, or earth movements such as landslides and creep.

Estuary – Region of interaction between rivers and near-shore ocean waters, where tidal action and river flow mix fresh and salt water. Such areas include bays, mouths of rivers, salt marshes, and lagoons

Eutrophication – A rapid increase in algae or plant growth in an aquatic system that chokes a body of water out of existence.

Evapotranspiration – The transfer of water into the atmosphere by evaporation and transpiration.

Transpiration – The release of water vapor by plants.

Exotic species – A nonnative species that is artificially introduced to an area.

Extinction – The loss or death of a group of organisms.

Extirpation – The extinction of a species or other group of organisms in a particular local area.


Fertilizer – A substance, often an artificial chemical mixture that is spread on or through the soil to make it more fertile.

Filter strip – A strip of permanent vegetation sufficiently wide and dense above a body of water so it will retard run-off and cause deposition, thus preventing silting in the water or structure below.

Filtration – The percolation of water through sand and other settled sediment to remove suspended particles.

Flood – A high flow of water that overruns its normal confinement area and covers land that is usually dry.

Food chain – A simple version of an energy sequence of links or trophic levels.

Food web – A graphic depiction of the interrelationships by which organisms consume other organisms.

Fossil fuel – Materials that consist of the remains of plants or animals that lived long ago and that are burned to produce energy (coal, oil, gas).


Grassed waterway – A natural or artificially made course for the flow of water, usually shallow, on which erosion-resistant grasses are grown, to permit water to run off fields thus reducing erosion where the crops are growing.

Grassroots organization – A group that is originated among or carried on by the common people.

Gray water – Untreated or partially treated wastewater that is used for such purposes as watering golf courses and lawns.

Greenhouse effect – The warming up of the lower atmosphere due to the accumulation of greenhouse gases that trap heat near the surface of the Earth.

Groundwater – A general term for the water beneath the Earth’s surface.

Growth rate – The rate at which a population is increasing in size.

Ground cover – Short plants, such as grasses, ferns, wildflowers, that form a layer on the ground in a forest.

Gully erosion – Removal of stones, gravel, and finer material by running water with the formation of channels that cannot be smoothed out completely by ordinary cultivation.


Habitat – The general place or physical environment in which a population lives.

Habitat Conservation Plans (HCPs) – As part of the Endangered Species Act, Habitat Conservation Plans are designed to protect a species while allowing development. HCPs give the U.S. Fish and Wildlife Service authority to permit “taking” of endangered or threatened species as long as the impact is reduced by conservation measures.

Habitat fragmentation – Habitat disruption where natural habitat is broken into small, relatively isolated fragments.

Hard water – Water that, because of its high level of dissolved solids, can dissolve little solute.

Hazardous wastes – Wastes that are particularly dangerous or destructive; specifically characterized by one or more of the following properties: ignitable, corrosive, reactive, or toxic.

Heavy metals – Metallic elements with high atomic weights; can damage living things at low concentrations and tend to accumulate in the food chain.

Herbicide – A chemical substance used to kill plant weeds.

Historic preservation – Protecting the irreplaceable; saving historic buildings and the neighborhoods and landscapes they anchor.

Horizon – A layer of soil with unique, distinguishable features.

Humus – Organic matter in soil.

Hydrologic cycle – Movement of water about the surface of the Earth, driven by energy from the sun.

Hydropower – The use of artificial or natural waterfalls to generate electricity.

Hydrosphere – The liquid water sphere or “layer” on Earth; it includes the oceans, rivers, lakes, streams, etc.


Impaired waters – Water bodies not fully supporting their uses.

Indicator species – A species in a community or ecosystem that is more susceptible to disturbances than most other species.

Indigenous – Species living naturally in a given area.

Industrial pollution – Unwanted materials from an industrial operation; may be liquid, sludge, or solid.

Infiltration – The rate of movement of water from the atmosphere into the soil.

Instream flow – The amount of flow required to sustain stream values, including fish, wildlife and recreation.

Integrated Pest Management (IPM) – Integrated Pest Management and the concept of biological control follow the basic philosophy that the farmer should not try to totally eliminate pests, but should simply attempt to control them so that they do not cause serious damage. IPM and biological control often use “natural” controls, such as the pests’ natural biological predators.

In situ – In its natural place.

Irrigation – The artificial watering of land.


Keystone species – A certain species that one or more other species are dependent upon for food, reproduction, or some other basic need.


Landfill – A place where solid waste is stored.

Land-use planning – The process of deciding appropriate uses of land.

Leachate – A liquid solution that forms as water percolates through waste, such as refuse in a landfill or old mining tailings.

Leaching – The removal by percolating water of soluble constituents from the soil or other material.

Lentic ecosystem – Vary considerably in physical, chemical, and biological characteristics (ponds, pools, swamps, bogs, lakes, etc.).

Lichen – A symbiotic association or relationship of an alga and a fungus, which forms crustose, foliose, or fruticose bodies.

Life cycle – The phases, changes, or stages an organism passes through from a fertilized egg to death of the mature plant or animal.

Limnetic zone – Zone of a lentic ecosystem from the open water down to the depth of light penetration.

Lithosphere – The rock sphere or layer that forms the surface of the Earth; composed of the crust and uppermost portion of the mantle.

Littoral zone – Zone of a lentic ecosystem (pond, lake) that extends from the shoreline to the innermost rooted plants, successively passing from rooted emergent forms, rooted species with floating leaves, and in deeper waters to various submerged but rooted species.


Managed growth – Management in which trees in a given stand are maintained at all ages and all sizes to permit continuous natural regeneration of the stand.

Maximum contaminant level (MCL) – The highest concentrations allowed by the EPA in water designated for certain uses.

Microhabitat – The specific parts of a habitat actually encountered by an individual.

Microirrigation – Method of irrigation in which water is transported to crops through pipes and then dripped onto the plants through tiny holes in the pipes, which are installed on or below the surface of the soil; sometimes called drip irrigation.

Minerals – Naturally occurring, inorganic, abiotic material made up of one or more elements.

Mixed deciduous forest – General name for a large, complex vegetational unit dominated by deciduous trees.

Mixing zone – A portion of a waterbody where water quality criteria or rules are waived in order to allow for dilution of pollution.

Monoculture – A form of agriculture where only a single species is grown in a particular field.

Multiple-use principle – When land is put to many uses at the same time, such as logging, mining, grazing, farming, oil exploration, hunting, fishing, and so forth.

Municipal sewage – Wastes originating from a community; may be composed of domestic wastewaters and/or industrial wastewaters.


National Estuary Program – A program established under the Clean Water Act Amendments of 1987 to develop and implement conservation and management plans for protecting estuaries and restoring and maintaining their chemical, physical, and biological integrity, as well as controlling point and nonpoint pollution sources.

National Pollutant Discharge Elimination System (NPDES) – A provision of the Clean Water Act which prohibits discharge of pollutants into waters of the United States unless special permit is issued by EPA, a state, or where delegated, a tribal government.

Native species – A species which is a natural member of a biotic community; humans were not involved in the colonization of the species.

Natural environment – The physical and biological environments independent of human technological intervention.

Natural selection – The basic mechanism of evolutionary change, first formulated by Charles

Navigable waters – Traditionally, waters sufficiently deep and wide for navigation; such waters in the United States come under federal jurisdiction and are protected by the Clean Water Act.

Net yield – The concept of net yield for nonrenewable resources holds that a resource can continue to be extracted as long as the resources used in extraction do not exceed the resources gained.

Niche – Ecological role of a species in an environment, or the conditions within which the organism persists.

Nonpoint source – Diffuse pollution sources (i.e. without a single point of origin or not introduced into receiving stream from a specific outlet).

Nonrenewable resource – A resource, such as fossil fuels, that does not significantly regenerate itself on a human time scale.

Nutrient cycling – Recycling of elemental atoms, such as nitrogen and phosphorous, through an ecosystem.

Nutrient pollution – Contamination of water resources by excessive inputs of nutrients. In surface waters, excess algal production as a result of nutrient pollution is a major concern.


Old Growth Forest – An ancient forest; a forest that has reached the final stage of succession. The forest has tall conifers; smaller trees living below the big trees can survive in the shade of these conifers, and many snags and logs.

Oligotrophic – Nutrient-poor (lakes).

Open system – A system that is not isolated in that it exchanges matter and/or energy with other systems.

Organic pollution – Occurs when carbonous waste contained in plant or animal matter is released from domestic or industrial sources.

Organophosphates – A group of synthetic organic pesticides that are less persistent, but more toxic to humans, than chlorinated hydrocarbons; includes malathion and parathion.

Outfall – The place where effluent is discharged into receiving waters.

Ozone – An O3 molecule. Ozone contributes to air pollution in the troposphere, but is an important natural component of the stratosphere. The stratospheric ozone layer protects the Earth’s surface from excessive levels of ultraviolet radiation.

Ozone layer – A layer of ozone in the stratosphere most concentrated at an altitude between about 12 and 16 miles.


Parasitism – Occurs where one species (the parasite) lives off another species (the host) and may actively harm the host; often considered a form of symbiosis.

Parent stream – The stream yielding a tributary during stream capture.

Pelagic – Refers to the water column zone of the aquatic (specifically, marine) biome.

Percent annual growth – The rate of natural increase expressed as a percentage of the given population.

Persistence – The amount of time a pollutant stays in the environment in an unmodified form.

Pesticide – A chemical substance used to destroy animal pests, such as insects, that might attack a crop.

pH – An expression of the intensity of the basic or acid condition of a liquid with a range from 0 – 14, where 0 is most acidic and 14 is most basic.

Phosphorus – A chemical commonly used in fertilizers that can be harmful to the aquatic life of lakes and other bodies of water.

Photochemical pollutant – A pollutant produced when sunlight initiates chemical reactions among NOx, volatile organic compounds, and other substances found in the air.

Photosynthesis – The process by which organisms such as green plants convert light energy to chemical energy and synthesize organic compounds from water and carbon dioxide.

Physical environment – The natural physical nonliving world, including the lithosphere, hydrosphere, and atmosphere.

Pioneer species – A plant or animal capable of establishing itself in a barren area and starting succession.

Point source – A stationary location or fixed facility from which pollutants are discharged or emitted.

Polluted water – Water that is rendered unusable for its intended purpose.

Pollution – A term often used to refer to excess outputs by society into the environment.

Population – A group of organisms, all of the same species that occupies a particular area.

Precipitation – Removal of water from the atmosphere as rain, snow, sleet, or hail.

Predation – The process in which certain organisms kill and consume other organisms.

Preservation – Refers to nonuse, such as a “preserve” that is set aside and protected in its pristine natural state.

Preservationism – The classical view that nature should be preserved for its own sake.

Primary pollutants – Pollutants that are directly emitted by coal-burning power plants.

Primary standards – Under the drinking water standards of the Safe Drinking Water Act, primary standards specify contaminant levels based on health-related criteria.

Primary treatment – The use of physical processes, especially screening and settling, to remove materials from water.

Pristine – Characteristic of the earliest period or condition; original, uncorrupted, unspoiled.

Producer – Organisms that use the photosynthetic process to assimilate carbon dioxide into energy-rich carbon compounds.

Profundal zone – Zone of a lentic ecosystem that occurs below the limnetic zone and in deep lakes it may constitute the largest water volume of a lake.


Raw materials – Materials before being processed or manufactured into a final form.

Receiving waters – All distinct bodies of water that receive runoff or wastewater discharges, such as streams, rivers, ponds, lakes, and estuaries.

Recharge area – An area where rainfall can infiltrate into an aquifer.

Reclamation – Beneficially using materials found in the waste stream. Restoring land to pre-disturbance conditions.

Recovery rate – The amount of the original material that can actually be recovered and recycled.

Recycling – Minimizing waste generation by using the same resource over and over, but in a modified form.

Redd – Nest of a fish, especially trout and salmon.

Reforestation – Measure taken to return a site to its original conditions.

Regulatory agencies – Agencies that are part of the executive branch of the government and are responsible for administering and enforcing laws enacted by Congress.

Reintroduction – Release of plants and animals back into habitat that they formerly occupied, but in which they may have become locally scarce or extinct.

Remediation – Efforts to counteract some or all of the effects of pollution after it has been released into the environment.

Renewable energy – An energy source that, from an Earth perspective, is continually renewed.

Renewable resource – A resource that will regenerate within a human time scale; for example, crops and energy received from the Sun.

Reproductive success – Relative to other individuals in the population, the number of offspring that reproduce.

Residence time – The time it takes for a pollutant to move through the environment.

Resource – A source of raw materials used by society.

Restoration – The process of returning a degraded resource to its natural state.

Reuse – Using the same resource over and over again in the same form.

Rill erosion – The removal of soil by running water resulting in the formation of shallow channels that can be smoothed completely by cultivation in the normal manner.

Riparian – Terrestrial community alongside a watercourse.

Riparian law – A law under which the owner of land has the right to withdraw water that is adjacent to the land, such as from a river or lake.


Safe Drinking Water Act (SDWA) – A federal statute enacted in 1974 that aimed explicitly at improving the quality of drinking water by establishing primary and secondary standards for contaminant levels in water.

Salinization – An increase in soil salt content that sometimes occurs due to prolonged irrigation, e Sanitary sewer. A sewer that transports only wastewaters (from domestic residences and/or industries) to a wastewater treatment plant.specially in poorly drained arid regions.

Sapling – A young tree.

Saturation, zone of – The region below the water table where all voids in the soil and rock are fully filled with water.

Second growth forest – Forest in which the trees have grown up naturally following a drastic interference such as logging, fire, or insect epidemic.

Secondary pollutants – Pollutants produced as a result of reactions among other air pollutants, such as photochemical pollutants.

Secondary standards – Under the drinking water standards of the Safe Drinking Water Act, secondary standards specify contaminant levels based on nonhealth-related criteria.

Secondary treatment – The use of biological processes to remove materials from polluted water.

Sediment – Soil, sand, and minerals washed from land into water, usually after rain.

Sedimentary processes – Natural processes that may concentrate minerals through precipitation from a solution or by differential settling of grains in moving or still water.

Sedimentary rock – Rock formed from fragments of other rock transported from its source, typically by water or wind, and deposited elsewhere.

Sedimentation – The settling out of suspended particles from a body of water.

Seedling – A plant grown from a seed rather than a cutting or by grafting; young tree less than three feet tall.

Selective cutting – The harvesting of trees such that only certain trees are cut down and the land is not stripped bare; also known as uneven-aged management.

Septic system – An on-site system designed to treat and dispose of domestic sewage. A typical septic system consists of a tank that receives waste from a residence or business and a system of tile lines or a pit for disposal of the liquid effluent that remains after decomposition of the solids by bacteria in the tank and must be pumped out periodically.

Sewage – The waste matter and wastewater produced by residential and commercial sources.

Sheet erosion –The erosion or removal of a rather uniform layer of soil from the surface of the land by rainfall.

Sinkhole – A type of land subsidence, taking the form of a large depression in the gound, caused by water withdrawal. A sinkhole occurs when a thin layer of rock overlying an underground cavern collapses.

Slash and burn agriculture – A form of agriculture where trees and other vegetation are cut down and burned in order to clear the land and release nutrients into the soil.

Smog – Originally referred to a mixture of smoke and fog, but now generally refers to the brown haze of photochemical pollutants found in some urban areas.

Soft water – Water with low level of dissolved salts.

Soil – A mixture of weathered rocks and minerals, decayed organic matter, living organisms, air, and water that can sustain life.

Soil degradation – The damaging or destruction of natural soil; often due to overuse, abuse, and neglect by humans.

Soil fertility – The ability of the soil to support plant life and associated fauna.

Soil horizons – Layers of soil that form approximately parallel to the surface of the land; may include the topsoil, subsoil, a layer of partially disintegrated rock, and finally the underlying bedrock.

Sojourns – Multi-day paddling trips

Species – Often defined, at least for sexual organisms, as all of the organisms that can interbreed ( or potentially interbreed) to produce fertile offspring.

Species richness – The number of different species that occur in a given area.

Stewardship – The act of and desire to be in charge of and care for the planet; its natural resources and habitats.

Stream – A general term for water flowing in one direction such as a rill, creek, brook, and river.

Storm sewer – A system of pipes that carries water runoff from buildings and land surfaces.

Strip-mining – A form of surface mining, especially for coal, that is very destructive to the landscape.

Succession – Replacement of populations in a habitat through a regular progression.

Superfund – The common name for the federal Hazardous Substance Response Fund that is used to cleanup and related expenses associated with hazardous waste sites on the EPA’s National Priorities List.

Surface runoff – Water that runs across the top of the soil without infiltrating the soil.

Surface water – All water naturally open to the atmosphere.

Sustainable development – Development that focuses on making social, economic, and political progress to satisfy global human needs, desires, aspirations, and potential without damaging the environment; sometimes known as sustainable growth.

Sustainable harvesting – The sustainable us/harvesting of nuts, fruits, and other products that can be extracted from an ecosystem without causing damage; sometimes known as extractive forestry.

Sustainable technology – Technology that permits humans to meet their needs with minimum impact on the environment.

Sustainability – Meeting the needs of today without reducing the quality of life for future generations.

System – A set of components functioning together as a whole.


Technology-based standards – Minimum pollutant control standards for numerous categories of industrial discharges, sewage discharges and other types of discharges.

Thermal inversion – Occurs when a layer of warm air overlies cooler air in the troposphere (lower atmosphere), thus inverting the usual condition in which air becomes cooler as altitude increases.

Thermal stratification – The condition of a body of water in which the successive horizontal layers have different temperatures, each layer more or less sharply differentiated from the adjacent ones, warmest at top.

Threatened waters – Water whose quality supports beneficial uses now but may not in the future unless action is taken.

Threshold of exposure – The smallest amount of a poison or other toxic substance that is necessary to cause harm.

Topsoil – An upper layer of soil, composed primarily of a mixture of organic matter and mineral matter; it is alive with microscopic and small macroscopic organisms.

Total Maximum daily load (TMDL) – The sum of the individual wasteload allocations (WLAs) for point sources, load allocations (Las) for nonpoint sources and natural background, and margin of safety (MOS).

Toxicity The degree to which a substance or mixture of substances can harm humans or animals.

Toxicology – The study of the effects of chemicals that are harmful or fatal when consumed by organisms in relatively small amounts.

Toxics Release Inventory (TRI) – A report compiled annually by the Environmental Protection Agency on toxics released by U.S. industries based on data reported to the EPA by those industries under the Emergency Planning and Community Right-to-Know Act of 1986.

Toxin – A poisonous substance produced by an organism; the term is sometimes used to refer to any toxic substance in general.

Transgenic crops – Genetically transformed crops; crops that have been artificially engineered using bioengineering.

Trophic species – Collection of organisms that feed on a common set of organisms and are fed on by another common set of organisms.

Troposphere – The lowermost thermal layer of the atmosphere, wherein temperatures normally decline with increasing altitude; the layer of the atmosphere in which most weather phenomena take place.

Turnover – (1) The mixing of layers of water in lakes in the spring and autumn. (2) The period of time required for an organism to grow, mature, die and undergo decomposition.


Ultimate cause – Aspect of the environment that influences direction of natural selection.

Umbrella species – A large, charismatic species. When the habitat for such a species is protected, many other species will be protected as well.

Understory – Set of plants deploying leaves at 5 to 15 feet high that form a forest’s middle layer.

Unique species – Species that are not closely related to any other living species.

Urbanization – The trend toward increasing numbers of people living in cities.

Urban runoff – Stormwater from city streets and adjacent domestic or commercial properties that may carry pollutants of various kinds into the sewer systems and/or receiving waters.


Variable source area – The flexible zone adjacent to and extending the stream that contributes runoff to the channel during a runoff-producing event.


Wastewater – The used water and solids from a community (including used water from industrial processes) that flow to a treatment plant.

Wastwater treatment plant – A facility that receives wastewaters (and sometimes runoff) from domestic and/or industrial sources, and by a combination of physical, chemical, and biological processes reduces the wastewaters to less harmful byproducts. Also known as sewage treatment plant (STP) and publicly owned treatment works (POTW).

Water quality-based limitations – Effluent limitations applied to discharges when mere technology-based limitations would cause violations of water quality standards.

Water quality-based permit – A permit with an effluent limit more stringent than technology-based standards.

Water quality criteria – Levels of water quality considered necessary to protect a designated use.

Water quality standards – State-adopted and EPA approved standards for water bodies, including designated uses, water quality criteria and antidegradation requirements.

Water table – The boundary between the zones of aeration and saturation.

Waterlogging – The rising of the water table over time, and the soaking of soils, in areas where irrigated land is poorly drained. Waterlogging is often associated with salinization.

Watershed – The land area that drains into a stream. An area of land that contributes runoff to one specific delivery point; large watersheds may be composed of several smaller “subsheds,” each of which contributes runoff to different locations that ultimately combine at a common point.

Watershed management – The planned manipulation of one or more factors of the natural or disturbed drainage so as to effect a desired change in or maintain a desired condition of the water resource.

Weathering – The expansion and contraction in parent rock caused by shifts in temperature contribute to fragmenting and even pulverizing the rock.

Wetlands – Areas characterized by saturated or nearly saturated soils most of the year that form an interface between terrestrial and aquatic environments; include freshwater marshes around ponds and channels, brackish and salt marshes.

Wilderness Act of 1964 – A federal statute that allowed for the designation of wilderness area on federal lands that are to be managed so as to retain their primeval character.

Wind farm – A vast tract of land covered with wind-powered turbines that are used to drive generators that produce electricity.

Wind power – The harnessing of the wind’s energy for human applications.

Windbreak – A planting of trees and shrubs, usually in three or more rows to serve as a barrier to reduce or check the velocity of the wind.

Withdrawn water Water that is taken from its source; it may be returned to its source after use.


Xeric – Dry.

Xeriscaping – Landscaping designed to save water.

Acronyms and their Meanings


ACB – Alliance for the Chesapeake Bay
ALLARM – Alliance for Aquatic Resource Monitoring
AMD – Abandoned Mine Drainage
AML – Abandoned Mine Lands
AMR – Abandoned Mine Reclemation


BAMR – Bureau of Abandoned Mine Reclemation (DEP)
BOD – Biological Oxygen Demand
BMP – Best Management Practices


CBF – Chesapeake Bay Foundation
CSAW – Consortium for Scientific Assistance to Watersheds
CVI – Canaan Valley Institute
CVMP – Citizens’ Volunteer Monitoring Program


DCNR – Department of Conservation and Natural Resources
DEP – Department of Environmental Protection
DO – Dissolved Oxygen
DOC – Dissolved Organic Compounds
DRBC – Delaware River Basin Commission
DRKN – Delaware Riverkeeper Network


EAC – Environmental Advisory Council
EASI – Environmental Alliance for Senior Involvement
EMAP – Environmental Monitoring and Assessment Protocol (EPA)
EPCAMR – Eastern Pennsylvania Coalition for Abandoned Mine Reclamation
EPA – United States Environmental Protection Agency
EPT – Ephemeroptera (mayflies), Plecoptera (stoneflies), Trichoptera (caddis flies)


FBC – Pennsylvania Fish & Boat Commission (also seen as PA FBC)
FSN – Fixed Station Network (DEP)
FWS – United States Fish and Wildlife Serve


GG – Growing Greener (DEP Grants)
GWN – Ground Water Network (DEP)



IWLA – Izaak Walton League of America



KWN – Keystone Watershed Network


LWV – League of Women Voters


MOS – Margin of Safety
MTEC – Membrane Filtration Thermotolerant


NOAA – National Oceanic and Atmospheric Administration
NPDES – National Pollution Discharge Elimination System
NPS – Non Point Source
NWS – National Weather Service


OSM – Office of Surface Mining (EPA)


PACD – Pennsylvania Association of Conservation Districts
PALMS – Pennsylvania Lake Management Society
PANO – Pennsylvania Association of Non-Profit Organizations
PASDA – Pennsylvania Spatial Data Access
PASEC – Pennsylvania Senior Environment Corps
PEC – Pennsylvania Environmental Council
PGC – Pennsylvania Game Commission
POWR – Pennsylvania Organization for Watersheds and Rivers
PRWA – Pennsylvania Rural Water Association
PSATS – Pennsylvania State Association of Township Supervisors


QA/QC – Quality Assurance/Quality Control
QAPP – Quality Assurance Project Plan


RBP – Rapid Bioassessment Protocols (EPA program)
RPD – Relative Percent Difference
RN – River Network
RC&D – Resources Conservation & Development


SM – Standard Methods
SAC – Standard Analysis Codes
SOC – Synthetic Organic Compound
SRBC – Susquehanna River Basin Commission
SWAP – Source Water Assessment Program (DEP)
SWRC – Stroud Water Research Center


TMDL – Total Maximum Daily Load
TSI – Trophic State Index


USFS – United States Forest Service
USGS – United States Geological Survey


VOC – Volatile Organic Compound


WPAWPP – Western Pennsylvania Watershed Protection Program
WPC – Western Pennsylvania Conservancy
WPCAMR – Western Pennsylvania Coalition for Abandoned Mine Reclamation
WQN – Water Quality Network (DEP)
WREN – Water Resources Education Network