Glossary

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

algae

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

aquatic

relating to water, particularly freshwater

aquifer

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.

bankfull

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

baseflow

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

benthic

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

bioretention

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

BMP

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)

buffer

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

catchment

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

CCR

Comprehensive Characterization Report

channelization

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

cistern

an underground reservoir or tank for storing rainwater

coliform

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

conveyance

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

CSO

combined sewer overflow

CSS

combined sewer system

culvert

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

CWA

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)

dam

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

DCNR

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

detention

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

development

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

discharge

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

ecosystem

a collection of living things and their environment

effluent

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

encapsulated

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

encroachment

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

EPA

United States Environmental Protection Agency

erosion

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

estuary

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

FEMA

Federal Emergency Management Agency

FGM

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

floatables

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

flood

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

floodplain

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

fluvial

of or relating to flowing waters, especially rivers

GIS

Geographic Information Systems

grade

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

groundwater

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

hydraulic

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

impairment

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

impervious

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

infill

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

infiltration

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

infrastructure

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

inlet

the upstream end of any structure through which water may flow

insoluble

unable to pass into solution

invertebrates

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

IWMP

Ingetrated Watershed Management Plan

LID

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

LTCP

Long-Term Control Plan

macroinvertebrates

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

mainstem

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

MS4

Municipal Separate Sewer System

NOAA

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

NPDES

National Pollutant Discharge Elimination System

nutrient

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

O&M

Operations and Maintenance

OOW

Philadelphia Water Department’s Office of Watersheds

outfall

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

PA Act 167

Stormwater Management Act

PADCNR

Pennsylvania Department of Conservation and Natural Resources

PADEP

Pennsylvania Department of Environmental Protection

peak discharge

the maximum rate of stormwater runoff from a specific storm event

PEC

Pennsylvania Environmental Council

PFBC

Pennsylvania Fish and Boat Commission

phosphate

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

pipe

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.”

post-construction

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

pre-construction

prior to commencing construction activities

pretreatment

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

PWD

Philadelphia Water Department

RCP

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.

recharge

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

redevelopment

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

regulator

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

riffle

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

riparian

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

RTC

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

run

a reach of stream that is characterized by smooth flowing water

runoff

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

sediment

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

Silt

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

sinuosity

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

species

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

SSO

Sanitary Sewer Overflow

substrate

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

SWMM

Storm Water Management Model

toxic

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

transpiration

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

turbidity

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

unimpaired

natural, unmolested; destribing an unaltered or undisturbed state

USDA

United States Department of Agriculture

USGS

United States Geological Survey

vertebrate

a complex living thing having a backbone (vertebrae)

watercourse

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

watershed

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.