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terms for which definitions are available

agricultural activities

the work of producing crops and raising livestock including tillage, plowing, disking, harrowing, pasturing, mushroom growing, nursery, and sod operations and installation of conservation measures; construction of new buildings or impervious area is not considered an agricultural activity


any of a number of several groups of single-celled or multi-cellular organisms, all of which lack leaves, roots, flowers, and other organ structures that characterize higher plants


relating to water, particularly freshwater


an underground geologic feature containing water

asset management

Ability to manage infrastructure and other capital assets to minimize the total cost of owning and operating them, while delivering the service levels customer's desire.


the channel at the top-of-bank or point from where water begins to overflow onto a floodplain


flow in a stream that is not directly influenced by precipitation and is derived from groundwater; the sustained discharge that does not result from direct runoff or from water diversions, reservoir releases, piped discharges, or other human activities


used to describe aquatic organisms living at the bottom of a body of water

benthic macroinvertebrates

aquatic insect larvae that live on stream bottom; because of a short lifespan and relative immobility, they reflect the chemical and physical characteristics of a stream and chronic sources of pollution


a stormwater retention area that utilizes woody and herbaceous plants and soils to remove pollutants before infiltration occurs


Best Management Practice; a technique, measure, or structural control that addresses one or more objectives (e.g., a detention basin that gets built, an ordinance that gets passed, and an educational program that gets implemented)


the area of land immediately adjacent to any stream, measured perpendicular to and horizontally from the top-of-bank on both sides of a stream


the area of land that drains to a particular body of water or site on a waterbody; also see 'drainage area'


Comprehensive Characterization Report


the process of modifying the natural course of a stream in order to make it flow into or along a restricted path


an underground reservoir or tank for storing rainwater


of or relating to the bacilli (bacteria) that inhabit the intestines of warm-blooded animals


a facility or structure used for the transportation or transmission of something from one place to another


combined sewer overflow


combined sewer system


a metal, concrete, or plastic pipe that allows water to flow under a road or any other obstruction


Clean Water Act; a federal amendment that authorizes EPA to implement pollution control programs and set water quality standards for all contaminants in surface waters
“The Act made it unlawful for any person to discharge any pollutant from a point source into navigable waters, unless a permit was obtained under its provisions. It also funded the construction of sewage treatment plants under the construction grants program and recognized the need for planning to address the critical problems posed by nonpoint source pollution.” (Envoronmental Protection Agency website)


a man-made barrier, together with its appurtenant works, constructed for the purpose of impounding or storing water or another fluid or semifluid


Pennsylvania Department of Conservation and Natural Resources

defective lateral

a plumbing problem in which a lateral pipe is damaged, potentially leading to sanitary waste in a storm sewer and the receiving water body


the volume of runoff that is captured and released into the waters of this Commonwealth at a controlled rate

detention basin

an impoundment designed to collect and retard stormwater runoff by temporarily storing the runoff and releasing it at a predetermined rate; designed to drain completely soon after a rainfall event and become dry until the next rainfall event


any human-induced change to improved or unimproved real estate, whether public or private, including, but not limited to, land development, construction, installation, or expansion of a building or other structure, land division, street construction, and site alteration such as embankments, dredging, grubbing, grading, paving, parking or storage facilities, excavation, filling, stockpiling, or clearing


flow; a measure of the volume of water flowing through a defined area in a given time. Discharge is often abbreviated as Q, and measured in cubic feet per second (cfs)

drainage area

the area of land that drains to a particular body of water or site on a waterbody; also see 'catchment'

E. coli

Escherichia coli; a common rod-shaped bacterium that is found in the intestinal tract of warm blooded animals; used as an indicator of contamination by feces/sewage


a collection of living things and their environment


outflow of liquid waste, such as discharge from a sewer treatment plant


enclosed or covered, such a stream that has been built into a sewer


a structure or activity that changes, expands, or diminishes the course, current, or cross-section of a watercourse, floodway, or body of water


United States Environmental Protection Agency


the process by which soil particles are removed or displaced, usually by wind or water


a body of water intermediate between an ocean and river, usually tidal and highly productive


Federal Emergency Management Agency


Fluvial Geomorphology; the study of a stream’s interactions with the local climate, geology, topography, vegetation, and land use; the study of how a river carves its channel within its landscape


waterborne waste material and debris (e.g., plastics, polystyrene, paper) that float at or below the water surface


a temporary condition of partial or complete inundation of land areas from the overflow of streams, rivers, and other waters


any land area susceptible to inundation by water from any natural source or delineated by applicable Federal Emergency Management Agency maps and studies as being a special flood hazard area


of or relating to flowing waters, especially rivers


Geographic Information Systems


a slope, usually of a road, channel, or natural ground specified in percent


water beneath the earth’s surface that supplies wells and springs and is often between saturated soil and rock

groundwater recharge

the replenishment of existing natural underground water supplies from rain or overland flow


of or relating to forces exerted by a fluid, often water, under pressure


weakening, damage, or instability, such as the effects caused by pollution


incapable of being penetrated, such as a surface that does not absorb water


development that occurs on smaller parcels that remains undeveloped but is within or in very close proximity to urban or densely developed areas; usually relies on existing infrastructure and does not require an extension of water, sewer, or other public utilities


movement of surface water into the soil, where it is absorbed by plant roots, evaporated into the atmosphere, or percolated downward to recharge groundwater


the basic system of utilities and services needed to support a society; structures such as culverts, pipes, bridges, dams, and flood control measures can cause instability of streams and affect aquatic habitats


the upstream end of any structure through which water may flow


unable to pass into solution


animals, such as insects and crustaceans, that lack backbones (vertebrae)


Ingetrated Watershed Management Plan


Low-Impact Development; similar to “better site design” and “conservation site design”


Long-Term Control Plan


invertebrate animals that can be seen without the aid of a microscope


the main flow or central channel of a stream drainage network into which tributaries flow


Municipal Separate Sewer System


National Oceanic and Atmospheric Administration

non-point source pollution

pollution that comes from a diffuse source such as atmospheric deposition, stormwater runoff from pasture and cro pland, or individual on-lot domestic sewage systems discharging through shallow groundwater


National Pollutant Discharge Elimination System


an element or molecule needed for biological growth; when nutrients such as phosphorus are present in great concentrations, biological growth (algae in particular) can become overabundant, causing problems for aquatic ecosystems


Operations and Maintenance


Philadelphia Water Department’s Office of Watersheds


a pipe or other structure that discharges flow, such as treated sewage effluent or stormwater, to receiving waters

PA Act 167

Stormwater Management Act


Pennsylvania Department of Conservation and Natural Resources


Pennsylvania Department of Environmental Protection

peak discharge

the maximum rate of stormwater runoff from a specific storm event


Pennsylvania Environmental Council


Pennsylvania Fish and Boat Commission


an oxidized form of phosphorus, which may be organic or inorganic; inorganic phosphates are generally more likely to be available as nutrients for biological growth


a culvert, closed conduit, or similar structure (including appurtenances) that conveys stormwater

point source

pollution discharged from a single point, defined in the Clean Water Act as “any discernable, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, vessel, or other floating craft from which pollutants are or may be discharged.”


period after construction during which disturbed areas are stabilized, stormwater controls are in place and functioning, and all proposed improvements in the approved land development plan are completed


prior to commencing construction activities


techniques employed in stormwater Best Management Practices to provide storage or filtering to trap coarse materials and other pollutants before they enter the system


Philadelphia Water Department


River Conservation Plan; part of the PA Department of Conservation and Natural Resources’s Rivers Conservation Planning Program

receiving waters

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


the replenishment of groundwater through the infiltration of rainfall, other surface waters, or land application of water or treated wastewater


any development that requires demolition or removal of existing structures or impervious surfaces at a site and replacement with new impervious surfaces


in sewer infrastructure, a physical gate, valve, or other control structure that routes flow between two or more receiving pipes, usually one of which terminates in a combined sewer outfall


a reach of stream that is characterized by shallow, fast moving water broken by the presence of rocks and boulders


a vegetated area related to, within, or near a river or its that protects it from pollution and erosion

riparian corridor

the area of land along the bank or shoreline of a body of water (US Environmental Protection Agency's website)

roof drain

a drainage conduit or pipe that collects water runoff from a roof and leads it away from the structure


Real Time Control; a dynamic system of hydraulic controls to provide additional storage and reduce overflows from a combined sewer system


a reach of stream that is characterized by smooth flowing water


generally, precipitation that is not absorbed by surfaces or evaporated, but allowed to flow over the surface to a receiving body of water


particles, especially inorganic soil particles, that settle upon stream surfaces

sheet flow

a flow process associated with broad, shallow water movement on sloping ground surfaces that is not channelized or concentrated


inorganic sediment particles between 3.9 and 62.5 μm in diameter; 'siltation' is the process of being covered by or embedded in silt


a measure of the degree to which a stream, viewed from above, deviates from a linear path, expressed as the ratio of stream length between two points divided by the valley length, or point-to-point distance between the same two points


the level of biological taxonomic classification at which living things are separated from one another by the ability to reproduce yielding fertile offspring


Sanitary Sewer Overflow


a surface upon which living things grow; commonly, the bottom of a stream or river


Storm Water Management Model


describing a substance that is harmful, able to cause injury or death; toxicity is the concentration at which a substance may cause injury or death


the process by which water vapor passes through the membrane or pores of plants to the atmosphere


a measure of the cloudiness of water related to its particle content; often used as a proxy for water purity


natural, unmolested; destribing an unaltered or undisturbed state


United States Department of Agriculture


United States Geological Survey


a complex living thing having a backbone (vertebrae)


a channel or conveyance of surface water having a defined bed and banks, whether natural or artificial, with perennial or intermittent flow


The area of land draining to a stream, river, or other water body. Watershed boundaries are established where any precipitation falling within the boundary will drain to a single water body. Precipitation falling outside the boundary will drain to a different watershed. These boundaries are typically formed on high elevation ridges. The water bodies formed from the watershed drainage are usually at the lowest elevation in the watershed. Watersheds can also be called drainage basins.