Pennsylvania Code › Title 25 - ENVIRONMENTAL PROTECTION › Part I - Department of Environmental Protection › Subpart C - Protection of Natural Resources › Article II - Water Resources › Chapter 96 - WATER QUALITY STANDARDS IMPLEMENTATION › Section 96.1 - Definitions

Current through Register Vol. 54, No. 28, July 13, 2024
The following words and terms, when used in this chapter,
						have the following meanings, unless the context clearly indicates
						otherwise:
Concentration
-The amount of a substance,
						expressed in mass units, in a unit volume of water or wastewater.
Conservative substance
-A pollutant that
						undergoes no or minimal transformation or decay in a water system, except by
						dilution.
Cumulative loading
-The sum of pollutant
						loadings from individual pollutant sources.
Factor of safety
-A margin to take into
						account uncertainty concerning the relationships between effluent limitations
						and water quality.
Harmonic mean flow
-The flow that is
						determined by taking the reciprocal of the arithmetic mean of reciprocals of
						daily flow values.
LA-Load allocation
-The portion of a
						surface water's loading capacity that is assigned or allocated to existing and
						future nonpoint sources and natural quality.
Lake, pond or impoundment
-A surface
						water with a hydraulic residence time of 14 days or more based on average
						annual daily stream flow. Residence time shall be determined at average annual
						daily stream flow and normal pool volume. In the absence of actual records, an
						average annual daily discharge rate of 1.5 CFS per square mile shall be
						used.
Loading capacity
-The greatest amount of
						loading that a surface water can receive without violating a water quality
						standard.
Margin of safety
-The portion of a
						surface water's loading capacity that is set aside to account for uncertainty
						about the relationship between pollutant loadings and resulting surface water
						quality, including any uncertainty or imprecision in mathematical models used
						to determine these relationships. For nonconservative substances, any
						imprecision or uncertainty concerning the mechanisms by which the substance
						decays or is transformed shall be considered.
Mass load
-The pollutant loading
						expressed in units of mass per unit time.
NPDES
or
National Pollutant
						Discharge Elimination System Permit
-A permit issued under Chapter 92
						(relating to National Pollutant Discharge Elimination System permitting,
						monitoring and compliance) for the discharge or potential discharge of
						pollutants from a point source to surface waters.
Natural quality
-The water quality
						conditions that exist or that would reasonably be expected to exist in the
						absence of human related activity.
Nonconservative substance
-A pollutant
						whose concentration in the water column changes as a result of volatilization,
						photolysis, hydrolysis, biodegradation, transformation, or other processes,
						except dilution.
Nonpoint source
-A pollutant source which
						is not a point source discharge.
Nonpoint source restoration plan
-A
						nonpoint source management plan which describes needed actions to restore and
						improve water quality in a watershed or stream.
Point source discharge
-A pollutant
						source regulated under the NPDES permit system as defined in §
											92.1 (relating to
						definitions).
Pollutant
-Any contaminant or other
						alteration of the physical, chemical, biological, or radiological integrity of
						surface water which causes or has the potential to cause pollution as defined
						in section 1 of The Clean Streams Law (35 P. S. §
												691.1).
Potable water supply
-A water source that
						is used by humans after conventional treatment for drinking, culinary and other
						purposes such as inclusion in food products.
Q7-10 flow
-The actual or estimated
						lowest 7 consecutive-day average flow that occurs once in 10 years for a stream
						with unregulated flow, or the estimated minimum flow for a stream with
						regulated flow.
Q30-10 flow
-The actual or estimated
						lowest 30 consecutive-day average flow that occurs once in 10 years for a
						stream with unregulated flow, or the estimated 30 day average minimum flow for
						a stream with regulated flow.
Reserve factor
-A portion of the effluent
						flow held to provide for projected future wasteloads.
Surface waters
-Perennial and
						intermittent streams, rivers, lakes, reservoirs, ponds, wetlands, springs,
						natural seeps and estuaries, excluding water at facilities approved for
						wastewater treatment such as wastewater treatment impoundments, cooling water
						ponds, and constructed wetlands used as part of a wastewater treatment
						process.
TMDL-Total maximum daily load
-The sum of
						individual waste load allocations for point sources, load allocations for
						nonpoint sources and natural quality and a margin of safety expressed in terms
						of mass per time, toxicity or other appropriate measures.
WLA-Wasteload allocation
-The portion of
						a surface water's loading capacity that is allocated to existing and future
						point source discharges.
WQBEL-Water quality based effluent
						limitation
-An effluent limitation based on the need to attain or
						maintain the water quality criteria and to assure protection of existing and
						designated uses.
Water quality criteria duration
-The
						averaging period associated with a water quality criterion.
Water quality standards
-The combination
						of water uses to be protected and the water quality criteria necessary to
						protect those uses.
Wetlands
-Areas that are inundated or
						saturated by surface or groundwater at a frequency and duration sufficient to
						support, and that under normal circumstances do support, a prevalence of
						vegetation typically adapted for life in saturated soil conditions, including
						swamps, marshes, bogs and similar areas.