Glossary of Stormwater Terms

Dictionary

Aquifer: An underground geological formation or group of formations containing usable amounts of groundwater that can supply wells and springs.

Berm: A mound or wall of earth.

BMPs (Best Management Practices): Activities or structural improvements that help reduce the quantity and improve the quality of stormwater runoff. BMP’s include treatment requirements, operating procedures, and practices to control site runoff, spillage or leaks, or drainage from raw materials.

Buffer: A natural or vegetated area through which storm water runoff flows A buffer provides for infiltration of the runoff and filtering of pollutants.

Clean Water Act (CWA): The cornerstone of surface water protection. Legislation that provides statutory authority for the NPDES program. Also known as the Federal Water Pollution Control Act, passed in 1972.

Conservation: The use of water saving methods to reduce the amount of water needed for homes, lawns, farming, and industry, and thus increasing water supplies for optimum long term economic and social benefits.

Conservation Easement: Voluntary legal agreement between a landowner and conservation organization (government agency or land trust) that permanently limits some of the land's uses (primarily development rights).

Contaminant: Any physical, chemical, biological, or radiological substance causing an impurity in the environment.

Discharge: An outflow of water from a stream, pipe, groundwater aquifer, or watershed.

Drainage Basin: The area of land that drains to a given point on a body of water.  A drainage basin might also be referred to as a watershed or river basin.

Ecosystem: A community of animals and plants and the physical environment in which they live.

Effluent: Wastewater, treated or untreated, that flows out of a treatment plant, sewer, or industrial outfall. Generally refers to wastes discharged into surface waters.

Environment: The sum of all the external conditions that may act upon a living organism or community to influence its development or existence.

Erosion: A natural process of breaking away and moving soil or rock fragments by the action of water, wind, ice, or gravity.

Fecal Coliform: Bacteria found in the intestinal tracts of warm blooded animals. The presence of high numbers of fecal coliform bacteria in a water body can indicate the recent release of untreated sewage and/or the presence of animal feces. These organisms may also indicate the presence of pathogens that are harmful to humans.

Floodplain: The low land area adjacent to streams susceptible to being inundated by floodwaters and has a history of flooding during big storms.

Greenway: A corridor of natural floodplain that generally contain multi-use recreational trails.

Habitat: The place where a plant or animal species naturally lives and grows.

Hydrologic cycle: Also known as the water cycle. The paths water takes through its various states - vapor, liquid, solid - as it moves throughout the ocean, atmosphere, groundwater, streams, etc.

Illicit Discharge: Any discharge to a Municipal Separate Storm Sewer System (MS4) that is not entirely composed of stormwater. Sources of illicit discharges include sanitary wastewater, effluent from septic tanks, improper oil disposal, laundry wastewater, car wash wastewater (does not include private individuals or charity events), radiator flushing disposal, spills from roadway accidents, and improper disposal of auto and household toxins. Exceptions include NPDES permitted industrial sources and discharges from fire fighting activities.

Impervious area: The amount of hard surfaces like rooftops, parking lots, and roads.

Infiltration:  Entry of water from precipitation, irrigation, or runoff into the soil profile.

Nonpoint pollution: Contamination that does not originate from one specific location. Contamination that occurs when rainwater, snowmelt or irrigation runoff picks up soil particles and pollutants, such as nutrients, motor oil, pet waste and pesticides.

100-year flood: More accurately referred to as a "one percent chance flood," a flood of a magnitude that statistically has one chance in 100 of occurring in any given year.

Outfall: The place where a sewer, drain or stream discharges. 

Point Source Pollution: A type of pollution that can be traces to a specific source, such as a factory discharge pipe, ditches, channels, and sewers.

Pollution: Presence of a contaminant to such a degree that the environment (land, water, or air) is not suitable for a particular use.

Receiving Waters: Bodies of water that receive runoff or wastewater discharges, such as rivers, streams, lakes, estuaries, and ground water.

Riparian: Typically, lush, native vegetation along a stream or river.

Runoff: Rainwater, snowmelt and other water that is not absorbed into the ground but instead flows across the land picking up pollutants and eventually runs into streams and rivers.

Sediment: Eroded soil and rock material, and organic matter, transported and deposited by water. Sediment is the number one pollutant in streams in North Carolina.

Storm drain: Constructed opening in a road system through which runoff from the road surface flows into the closest receiving body of water.

Stream restoration: A program to reestablish the structure and function of an ecosystem, including its natural diversity and aquatic habitats, to a close approximation of the condition prior to human disturbance .

Surface water: Water above the surface of the land, including lakes, rivers, streams, ponds, floodwater, and runoff.

Watershed: Also called a drainage basin or river basin. An area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel. Everyone lives in a watershed.

Wetland: Areas that are regularly wet or flooded and have a water table that stands at or above the land surface for at least part of the year. Coastal wetlands extend back from estuaries and include salt marshes, tidal basins, marshes, and mangrove swamps. Inland freshwater wetlands consist of swamps, marshes, and bogs. Wetlands provide a habitat for aquatic life, terrestrial plants and animals. In addition, wetlands absorb floodwaters, excess nutrients, sediment and other pollutants.

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