Glossary of Terms
This page provides brief definitions of terms that are frequently used in discussions of watershed challenges and solutions.
Anadromous Fish: Migratory species that are born in freshwater, live mostly in estuaries and ocean water, and return to freshwater to spawn.
Atmospheric Deposition: The transfer of substances from the air to the surface of the Earth, either in wet form (rain, fog, snow, dew, frost, hail) or in dry form (gases, aerosols, particles).
Bacteria: (Singular: bacterium) 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.
Bathymetry: the measurement of water depth at various places in a body of water
Bedrock: Rock at or near (beneath soil and regolith) the Earth's surface that is solid and relatively unweathered.
Benthic: Term denoting the lower section of a surface or bottom dwelling.
BTEX: Benzene, toluene, ethyl benzene, and xylene – group of volatile organic compounds (VOC’s) found in petroleum hydrocarbons such as gasoline and other common environmental contaminants
Cryptosporidium: A protozoan microbe associated with the disease cryptosporidiosis in man. The disease can be transmitted through ingestion of drinking water, person-to-person contact, or other pathways, and can cause acute diarrhea, abdominal pain, vomiting, fever, and can be fatal as it was in the Milwaukee episode.
Detritus: Small pieces of dead and decomposing plants and animals; detached and broken-down fragments of structure; Pertains to small organic particles like leaves, twigs, etc.
Dissolved Oxygen (DO): The oxygen freely available in water, vital to fish and other aquatic life and for the prevention of odors. DO levels are considered a most important indicator of a water body's ability to support desirable aquatic life. Secondary and advanced waste treatment are generally designed to ensure adequate DO in waste-receiving waters.
Drainage Basin: The area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel.
Drawdown: The lowering of water levels stored behind a dam or other control structure. Change in reservoir elevation during a specified time interval.
Effluent: Wastewater--treated or untreated--that flows out of a treatment plant, sewer, or industrial outfall. Generally refers to wastes discharged into surface waters.
Emergent Vegetation: A plant that grows in shallow water with the root system submerged under the water and the upper vegetation rising above the water surface.
Epilimnion: The upper water layer in a stratified lake that is more or less uniformly warm in the summer
Erosion: The wearing away of land surface by wind or water, intensified by land-clearing practices related to farming, residential or industrial development, road building, or logging
Eutrophic Lakes: Shallow, murky bodies of water with concentrations of plant nutrients causing excessive production of algae.
Eutrophication: The slow aging process during which a lake, estuary, or bay evolves into a bog or marsh and eventually disappears. During the later stages of eutrophication the water body is choked by abundant plant life due to higher levels of nutritive compounds such as nitrogen and phosphorus. Human activities can accelerate the process.
Filter Strip: Strip or area of vegetation used for removing sediment, organic matter, and other pollutants from runoff and wastewater.
Gray Water: Domestic wastewater composed of wash water from kitchen, bathroom, and laundry sinks, tubs, and washers.
Ground Water: the supply of fresh water found beneath the Earth's surface, usually in aquifers, which supply wells and springs.
Herbicide: A chemical pesticide designed to control or destroy plants, weeds, or grasses.
Hydrologic cycle: The circulation of water from the sea, through the atmosphere, to the land, and thence back to the sea by overland and subterranean routes.
Hydrology: the science dealing with the properties, distribution, and circulation of water.
Hypolimnion: bottom waters of a thermally stratified lake.
Integrated Pest Management (IPM): A mixture of chemical and other, non-pesticide, methods to control pests.
Littoral Zone: 1. That portion of a body of fresh water extending from the shoreline lakeward to the limit of occupancy of rooted plants. 2. A strip of land along the shoreline between the high and low water levels
Metalimnion: The water layer of a stratified lake between the epilimnion and the hypolimnion characterized by a steep thermal gradient
Metamorphic rock: A rock that forms from the recrystallization of igneous, sedimentary, or other metamorphic rocks through pressure increase, temperature rise, or chemical alteration.
MTBE: Methyl tertiary butyl ether; a fuel oxygenate used in areas of poor air quality to allow gasoline to burn cleaner. Possible carcinogen and groundwater contaminant.
Microorganism: Extremely small organism that can only be seen using a microscope.
Non-Point Sources: Diffuse pollution sources (i.e. without a single point of origin or not introduced into a receiving stream from a specific outlet). The pollutants are generally carried off the land by storm water. Common non-point sources are agriculture, forestry, urban, mining, construction, dams, channels, land disposal, saltwater intrusion, and city streets.
Nutrient: Any substance assimilated by living things that promotes growth. The term is generally applied to nitrogen and phosphorus in wastewater, but is also applied to other essential and trace elements.
Nutrient cycling: The exchange of elements between the living and non-living components of an ecosystem.
Nutrient Pollution: Contamination of water resources by excessive inputs of nutrients. In surface waters, excess algal production is a major concern.
Organic Matter: Carbonaceous waste contained in plant or animal matter and originating from domestic or industrial sources.
Organism: Any form of animal or plant life.
Particulates: 1. Fine liquid or solid particles such as dust, smoke, mist, fumes, or smog, found in air or emissions. 2. Very small solids suspended in water; they can vary in size, shape, density and electrical charge and can be gathered together by coagulation and flocculation
Pathogens: Microorganisms (e.g., bacteria, viruses, or parasites) that can cause disease in humans, animals and plants.
Pesticide: Substances or mixture there of intended for preventing, destroying, repelling, or mitigating any pest. Also, any substance or mixture intended for use as a plant regulator, defoliant, or desiccant.
Petroleum: Crude oil or any fraction thereof that is liquid under normal conditions of temperature and pressure. The term includes petroleum-based substances comprising a complex blend of hydrocarbons derived from crude oil through the process of separation, conversion, upgrading, and finishing, such as motor fuel, jet oil, lubricants, petroleum solvents, and used oil.
Permeability: A measure of the ability of soil, sediments, and rock to transport water horizontally and vertically. Permeability is dependent on the porosity of the medium the water is flowing through. Some rocks like granite have very poor permeability, while rocks like shale are actually quite pervious. As for soil, sand is the most pervious, while clay has the lowest permeability. Silt is usually somewhere in the middle.
pH: An expression of the intensity of the basic or acid condition of a liquid; may range from 0 to 14, where 0 is the most acid and 7 is neutral. Natural waters usually have a pH between 6.5 and 8.5.
Phosphorus: An essential chemical food element that can contribute to the eutrophication of lakes and other water bodies.
Photosynthesis: the chemical process where plants and bacteria utilize atmospheric carbon dioxide and water plus light energy from the sun to create usable energy.
Plankton: Microorganisms suspended in the water having little or not power of locomotion carried by waves, currents and other movements of water.
Point Source: A stationary location or fixed facility from which pollutants are discharged; any single identifiable source of pollution; e.g. a pipe, ditch, ship, ore pit, factory smokestack.
Pollutant: Generally, any substance introduced into the environment that adversely affects the usefulness of a resource or the health of humans, animals, or ecosystems..
Protozoa: One-celled animals that are larger and more complex than bacteria. May cause disease.
Suspended Solids: Small particles of solid pollutants that float on the surface of, or are suspended in, sewage or other liquids. They resist removal by conventional means.
Topography: The physical features of a surface area including relative elevations and the position of natural and man-made (anthropogenic) features.
TMDL: Total Maximum Daily Load (TMDL) is the amount of a particular pollutant that a particular stream, lake, estuary or other waterbody can 'handle' without violating state water quality standards.
Transpiration: The process by which water vapor is lost to the atmosphere from living plants. The term can also be applied to the quantity of water thus dissipated.
Turbidity: A cloudy condition in water due to suspended silt or organic matter
Watershed: The land area that drains into a stream; the watershed for a major river may encompass a number of smaller watersheds that ultimately combine at a common point.
Wetlands: An area that is saturated by surface or ground water with vegetation adapted for life under those soil conditions, as swamps, bogs, fens, marshes, and estuaries.