Watershed Glossary
More detailed glossaries can be found at the United States Geological Survey and at the Water on the Web.
AB
Acid rain - natural rainfall which contains nitric and sulfuric acids due to oxides of nitrogen and sulfur dioxide discharged into the air by industries, power plants, and automobiles.
Algae - a nontaxonomic term that characterizes a group of simple aquatic plants. They may occur as single cells, colonies, or filaments. Through photosynthesis they produce most of the food and oxygen available in an aquatic environment and their growth is dependent on the amount of nutrients (e.g. nitrogen and phosphorus) available in the water. Algae range from phytoplankton (microscopic plants that float in water bodies) to large kelps.
Amphibian - a cold-blooded vertebrate that spends some time on land but must breed and develop into an adult in water -- frogs, salamanders, and toads are amphibians.
Anaerobic - not containing oxygen or not requiring oxygen.
Anoxic - a condition where no oxygen is present.
Aquatic - living in water.
Backwater - a still body of water or a still portion of a larger body of water, unaffected by the flow of the larger body of water. An example would be a small stagnant branch of a river.
Baseflow - stream or river flows consisting entirely of groundwater contributions.
Baseline - the numeric level of nutrient load at a particular point in time that serves to establish nutrient reduction goals and allowances.
Best Management Practices (BMPs) - a practice or combination of practices that provide the most effective and practicable means of controlling point and nonpoint pollutants at levels compatible with environmental quality goals.
Bedload - sediment or other material that slides, rolls or bounces along a stream or channel bed of flowing water.
Bioaccumulation - a process of accumulation of contaminants in the tissue of an organism through the the organism's interaction with the surrounding environment. This process is magnified through the food chain. For example, in aquatic environments plankton are the base of the food chain. The relative concentration of a pollutant in the plankton or aquatic insects may be small, however a fish might consume a large quantity of plankton or aquatic insects over the course of its lifetime. By doing so, the fish is continually adding to the concentration of pollution in its tissue such that eventually the fish might be unsafe for human consumption.
Biological Diversity - the variety of life in all its forms, levels and combinations including ecosystem diversity, species diversity and genetic diversity.
Bioretention - bioretention sites, also called "rain gardens," are an innovative method for stormwater management that retains stormwater on site and uses plants and layers of soil, sand, and mulch to reduce the amount of nutrients and other pollutants that enter local waterways.
Bioswales - shallow, wide grassed channels that both transport and absorb stormwater
Biota - the flora and fauna of a region.
Bloom - a population burst of algae, or phytoplankton, usually caused by an excess of nutrients (Nitrogen and Phosphorus) that remains within a defined part of the water column. These large quantities of algae eventually die off and in the process deoxygenate the water. This often results in the death of other aquatic plants or animals.
Bog - a wetland that has poorly drained acidic peat-soil dominated by sedges and sphagnum moss.
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CD
Chlorophyll a - a pigment contained in plants that is used to turn light energy into food. Chlorophyll also gives plants their green color.
Coliform bacteria - a group of bacteria primarily found in human and animal intestines and wastes. These bacteria are widely used as indicator organisms to show the presence of such wastes in water and the possible presence of pathogenic (disease-producing) bacteria. Escherichia coli (E. coli) is one of the fecal coliform bacteria widely used for this purpose.
Constructed wetlands - are stormwater management structures that use natural processes to detain and treat runoff from developed areas.
Contaminant - anything that to make something impure, unclean, or polluted, especially by mixing harmful impurities into it or by putting it in contact with something harmful.
Decreased drought flow - inadequate groundwater recharge causes diminished or loss of flow in watercourses.
Denitrification - the conversion of nitrite and nitrate nitrogen (after nitrification) to inert nitrogen gas. This treatment process requires that little or no oxygen be present in the system and that an organic food source be provided to foster growth of another type of bacteria. The organic food source can be either recycled waste activated sludge or methanol. The resultant nitrogen gas is released to the atmosphere.
Detritus - accumulated organic debris from dead organisms, often an important source of nutrients in a food web.
Dischargers – the sources that emit, give off, or dispose of a gas or liquid.
Dissolved Inorganic Nitrogen (DIN) - an important nutrient for the growth of plants. DIN is nitrogen that is readily usable by plants.
Dissolved Oxygen (DO) - microscopic bubbles of oxygen that are mixed in the water and occur between water molecules. Dissolved oxygen is necessary for healthy lakes, rivers, and estuaries. Most aquatic plants and animals need oxygen to survive. Fish will drown in water when the dissolved oxygen levels get too low. The absence of dissolved oxygen in water is a sign of possible pollution.
Diurnal - active during daylight.
Diversity - an ecological measure of the variety of organisms present in a habitat.
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EF
Easement - a limited right to make use of a property owned by another, for example, a right of way across the property.
Ecology - the study of interrelationships between living things and to their environment
Ecosystem - all the organisms in a particular region and the environment in which they live. The elements of an ecosystem interact with each other in some way, and so depend on each other either directly or indirectly.
Effluent - the discharge to a body of water from a defined source, generally consisting of a mixture of waste and water from industrial or municipal facilities.
Emissions - refers to pollution being released or discharged into the air from natural or man-made sources. Pollutants may be released directly into the air from a structural device (i.e., smokestack, chimney, exhaust pipe) or indirectly via volatilization or dispersal (i.e., aerosol spraying).
Endangered - a species that is in immediate danger of becoming extinct and needs protection to survive.
Endemic species - a species that is restricted in its distribution to a particular locality or region.
Environment - the place in which an organism lives, and the circumstances under which it lives. Environment includes measures like moisture and temperature, as much as it refers to the actual physical place where an organism is found.
Erosion - the disruption and movement of soil particles by wind, water, or ice, either occurring naturally or as a result of land use.
Eutrophic - describes an aquatic system with high nutrient concentrations. These nutrient concentrations fuel algal growth. This algae eventually dies and decomposes, with reduces the amount of dissolved oxygen in the water.
Eutrophication - the process of excess nutrients accelerating the growth of algae, oftentimes ultimately depleting the water of oxygen.
Exotic species - any introduced plant or animal species that is not native to the area and that may be considered a nuisance.
Extinct species - a species which has disappeared from existence due to either natural or human-induced means.
Floodplain - area around a river or creek that is periodically flooded when the main channel of a river exceeds its carrying capacity.
Food chain / food web - the network of feeding relationships in a community as a series of links of trophic levels, such as primary producers, herbivores, and primary carnivores. Includes all interactions of predator and prey, along with the exchange of nutrients into and out of the soil. These interactions connect the various members of an ecosystem, and describe how energy passes from one organism to another.
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GHI
Grey water - wastewater other than sewage, such as sink or washing machine drainage.
Groundwater - subsurface water that accumulates and returns to the surface in wells springs and watercourses.
Habitat - the place and conditions in which an organism lives.
Heavy metals - any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations.
Hydrologic - the cyclic phenomena of waters of the earth - precipitation, runoff, storage and evaporation
Hydrological - the scientific study of the properties, distribution, and effects of water on the earth's surface, in the soil and underlying rocks, and in the atmosphere.
Hypoxic - a condition where only very low levels of oxygen are present.
Indigenous species - a species which evolved on the North American continent, was present at the time of European Colonization, and is resident within the Upstate of South Carolina without human manipulation.
Integrated Pest Management (IPM) - a sustainable pest management approach which combines the use of biological, cultural, physical, and chemical tactics in a way that minimizes economic, health and environmental risks. One aspect of IPM involves regular monitoring (scouting) to determine if and when treatments are needed based on biological and/or aesthetic thresholds to keep pest numbers low enough to prevent intolerable damage or annoyance (economic threshold).
Impaired waters list (or impairments) - impaired waters are waters that do not meet State water quality standards. Under the Clean Water Act, section 303(d), States, territories and authorized tribes are required to develop lists of impaired waters. The law requires that these jurisdictions establish priority rankings for waters on the lists and develop TMDLs for these waters.
Impervious - surfaces that will not allow things to pass through. Paved roads, sidewalks and driveways are examples because water does pass through them and instead runs off.
Infrastructure - the physical systems that support community function (roads, sewers, water lines).
Introduced species - species which have been intentionally or inadvertently brought into a region or area. Also called exotic species.
Invertebrate - animals which lack a backbone and include such as squids, octopuses, lobsters, or shrimps, crabs, shellfishes, sea urchins and starfishes.
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JKL
Juvenile - strictly speaking, a juvenile is any of a species which is not yet sexually mature. In the context of many surveys, however, it is most often used interchangeably with young-of-year (YOY).
Keystone species - a predator at the top of a food web, or discrete subweb, capable of consuming organisms of more than one trophic level beneath it.
Land cover - anything that exists on, and is visible from above, the earth's surface. Examples include vegetation, exposed or barren land, water, snow, and ice.
Land use - the way land is developed and used in terms of the kinds of anthropogenic activities that occur (e.g. agriculture, residential areas, industrial areas).
Legacy contaminants - residual chemicals, heavy metals and other pollutants imbedded within the sediment of river and lake bottoms as a result of past water pollution.
Low Impact Development (LID) - a comprehensive land planning and engineering design approach with a goal of maintaining and enhancing the pre-development hydrologic regime of urban and developing watersheds. This design approach incorporates strategic planning with micro-management techniques to achieve superior environmental protection, while allowing for development or infrastructure rehabilitation to occur.
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MN
Marsh - an emergent wetland that is usually seasonally flooded or wet, and often dominated by one or a few plant species.
Migratory - describing groups of organisms which move from one habitat to another on a regular or seasonal basis.
Native species - species which have lived in a particular region or area for an extended period of time.
Niche - a general term referring to the range of environmental space occupied by a species.
Nitrification – the process to which bacterial populations under aerobic conditions, gradually oxidize ammonium to nitrate with the intermediate formation of nitrite. Biological nitrification is a key step in nitrogen removal in wastewater treatment systems.
Nitrogen - (N) is used primarily by plants and animals to synthesize protein. Nitrogen enters the ecosystem in several chemical forms and also occurs in other dissolved or particulate forms, such as tissues of living and dead organisms.
Nocturnal - active only at night.
Nonpoint source - a diffuse source of pollution that cannot be attributed to a clearly identifiable, specific physical location or a defined discharge channel. This includes the nutrients that runoff the ground from any land use - croplands, feedlots, lawns, parking lots, streets, forests, etc. - and enter waterways. It also includes nutrients that enter through air pollution, through the groundwater, or from septic systems.
Nutrients - compounds of nitrogen and phosphorus dissolved in water which are essential to both plants and animals. Too much nitrogen and phosphorus act as pollutants and can lead to unwanted consequences - primarily algae blooms that cloud the water and rob it of oxygen critical to most forms of aquatic life. Sewage treatment plants, industries, vehicle exhaust, acid rain, and runoff from agricultural, residential and urban areas are sources of nutrients entering the Bay.
Nutrient Removal Technology (NRT) - also known as biological nutrient removal (BNR). The process whereby nutrients are removed from wastewater in addition to the organic content.
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OPQ
Oligotrophic - refers to water bodies or habitats with low concentrations of nutrients.
Open space - an area of land that is valued for natural processes and wildlife, for agricultural and sylvan production, for active and passive recreation, and providing other public benefits.
Pervious - porous, able to be penetrated by water.
Pesticides - a general term used to describe chemical substances that are used to destroy or control insect or plant pests. Many of these substances are manufactured and do not occur naturally in the environment. Others are natural toxics that are extracted from plants and animals.
pH - measure of the acidity or basicity of water (-log10 of the activity of hydrogen ions in water).
Phosphorus - ((P) a key nutrient in the many ecosystems, phosphorus occurs in dissolved organic and inorganic forms, often attached to particles of sediment. This nutrient is a vital component in the process of converting sunlight into usable energy forms for the production of food and fiber. It is also essential to cellular growth and reproduction for organisms such as phytoplankton and bacteria. Phosphates, the inorganic form are preferred, but organisms will use other forms of phosphorus when phosphates are unavailable.
Piedmont - the Piedmont Ecoregion occupies an area between the Southern Blue Ridge Escarpment and the Sandhills Ecoregion. The northwestern boundary is generally considered to be the base of the Blue Ridge Escarpment; the division between the crystalline rocks of the piedmont and the sedimentary rocks of the sandhills represents the southeastern boundary of this ecoregion. The piedmont-sandhill contact zone is marked in many river channels by shoals and rock ledges that collectively form the fall line. Gently rolling hills with many stream-cut valleys characterize the region with only a few level floodplains. In the lower piedmont, there are relatively few sharp breaks in topography except along major river valleys.
Point source - a source of pollution that can be attributed to a specific physical location; an identifiable, end of pipe "point". The vast majority of point source discharges for nutrients are from wastewater treatment plants, although some come from industries.
Polycyclic Aromatic Hydrocarbon (PAH) - a chemical compound composed of fused six carbon rings.
Polychlorinated Biphenyl (PCB) - a chemical compound composed of a bi-phenyl group and chlorine atoms.
ppt - parts per thousand (used as a measurement of salinity).
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RS
Rain garden - a garden bed that is sunken into the ground and prepared to encourage the capture, storage, and treatment of rain water.
Riparian area - riparian refers to the area of land adjacent to a body of water, stream, river, marsh, or shoreline. Riparian areas form the transition between the aquatic and the terrestrial environment.
Riparian forest buffers - an area of trees, usually accompanied by shrubs and other vegetation, that is adjacent to a body of water which is managed to maintain the integrity of stream channels and shorelines, to reduce the impact of upland sources of pollution by trapping, filtering, and converting sediments, nutrients, and other chemicals, and to supply food, cover, and thermal protection to fish and other wildlife.
Riverine - of a river or relating to or produced by a river
Sediment - matter that settles and accumulates on the bottom of a body of water or waterway.
Sedimentation - the separation of suspended particles from water by gravity Decreased drought flow – inadequate groundwater recharge causes diminished or loss of flow in watercourses.
Septic tank (septic systems) - an underground sewage disposal tank, generally installed to treat the wastewaters from an individual home, in which a continuous flow of waste material is decomposed by anaerobic (in the absence of oxygen) bacteria.
Siltation - the process by which sedimentary material, or silt, is suspended and deposited in a body of water.
Species - a population or group of populations that are in reproductive contact but are reproductively isolated from all other populations.
Sprawl - a form of land development that moves outward from urban areas in a manner which creates large areas of relatively low density.
Stormwater - water that accumulates on land as a result of storms, and can include runoff from urban areas such as roads and roofs.
Submerged Aquatic Vegetation (SAV) - rooted vegetation that grows under water in shallow zones where light penetrates. Also known as "Bay grasses".
Suspended sediments - particles of soil, sediment, living material, or detritus suspended in the water column.
Sustainability - the ability to continue existing.
Stream bank erosion - loss of bank material along a watercourse .
Storm flow - rainfall runoff that reaches a stream channel during, or soon after a rainfall event that causes high rates of discharge.
Swamp - a wetland dominated by woodsy vegetation.
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TUV
Terrestrial - living on land, as opposed to marine or aquatic.
Thermocline - a specific depth at which there is a layer of water where the temperature changes dramatically. Warmer surface water is separated from the cooler deep water. This temperature gradient results in the formation of a density barrier.
Threatened - a species that is likely to become endangered if not protected.
Total Maximum Daily Load (TMDL) - a TMDL defines the pollutant load that a water body can assimilate without causing violations of water quality standards, and allocates the loading between contributing point sources and non-point source categories.
Toxicant - a poisonous or toxic agent which is harmful to living resources either terrestrial or aquatic.
Tree canopy - refers to the layer of leaves, branches and stems of trees that cover the ground when viewed from above. This serves as an overall indicator of urban forest quality and quantity.
Tributary - a body of water flowing into a larger body of water. For example, the Saluda River is a tributary of Lake Greenwood.
Turbidity - the decreased clarity in a body of water due to the suspension of silt or sedimentary material.
Understory - just beneath the canopy, this layer of the forest is composed of small trees and shrubs. As older trees die, they leave a gap in the canopy, which younger trees quickly grow to fill.
Urban forest - is the system of trees and associated plants that grow individually, in small groups or under forest conditions on public and private lands in our cities, their suburbs and towns. This includes approximately 74.4 billion trees across the U.S. that surround us in parks, along streets and around private homes and businesses.
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.
Vertebrate - animals with a backbone including fish, amphibians, reptiles, birds, and mammals.
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WXYZ
Wastewater - water that has been used in homes, industries, and businesses that is not for reuse unless treated by a wastewater facility.
Waterfowl - any of various birds that swim on water, such as ducks, geese and swan or any bird species that is ecologically dependent on aquatic environments such as wetlands.
Water-quality criteria - criteria are part of a water quality standard, and may be numeric or narrative. Criteria represent a quality of water that supports a particular designated use. When criteria are met, water quality will generally protect the use.
Water quality standards - a provision of State or Federal law consisting of a designated use or uses for a water body and the quantifiable criteria protective of the use(s). Standards may be annual or seasonal, depending on the designated use.
Watershed - a region bounded at the periphery by physical barriers that cause water to part and ultimately drain to a particular body of water.
Wetlands - low areas such as swamps, tidal flats, and marshes which retain moisture.
Zooplankton - a community of floating, often microscopic animals that inhabit aquatic environments. Unlike phytoplankton, zooplankton cannot produce their own food, and so are consumers.
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