Wisconsin Administrative Code › Department of Natural Resources › NR 100-199 - Environmental Protection - General › Chapter NR 106 - Procedures For Calculating Water Quality Based Effluent Limitations For Point Source Discharges To Surface Waters › Subchapter I - Applicability › Section NR 106.03 - Definitions

Current through June 24, 2024
The following definitions are applicable to terms used in
					 this chapter.
(1g) "AMZ" means acute
				  mixing zone concentration based on presence of a zone of initial dilution under
				  s.
				  NR
				  106.06(3) (c).
(1r) "Bioaccumulative chemical of concern" or
				  "BCC" means any substance that has the potential to cause adverse effects
				  which, upon entering the surface waters, accumulates in aquatic organisms by a
				  human health or wildlife bioaccumulation factor greater than 1000.
(2) "Biologically based design flow" means a
				  receiving water design flow to protect fish and aquatic life for which both the
				  duration of exposure is expressed in days and the allowable frequency of
				  excursion is expressed in years. An example of a biologically based design flow
				  is a 4-day 3-year design flow which corresponds to the lowest 4-day average
				  flow that will limit excursions from any water quality criteria or secondary
				  values to no more than once in 3 years.
(2m) "Deficiency toxicity" means a condition
				  that exists when adverse effects occur to aquatic organisms because
				  concentrations of common ions are too low.
Note:
Changes in the concentration of ions in
					 surrounding waters can cause organisms to expend too much energy trying to
					 regulate the balance of water and dissolved materials in bodily fluids, and may
					 result in death.
Note:
Examples of common ions are sodium,
					 calcium, magnesium, potassium, etc.
(3) "Dynamic models" means computer
				  simulation models which use real or derived time series data to predict a time
				  series of observed or derived receiving water concentrations. Methods include
				  continuous simulation, Monte Carlo simulations, or other similar statistical or
				  deterministic techniques.
(4)
				  "EC50" means the point estimate of the concentration of
				  a toxic substance, wastewater effluent or other aqueous mixture which causes an
				  adverse effect including mortality to 50% of the exposed organisms in a given
				  time period, when compared to an appropriate control.
(4g) "Great Lakes" means the open Wisconsin
				  waters of Lake Superior, Lake Michigan, Green Bay, and Chequamegon Bay, as well
				  as adjoining open waters that exhibit characteristics of Lake Superior, Lake
				  Michigan, Green Bay, and Chequamegon Bay, or in other ways are determined by
				  the department to be equivalent to these waters.
(4r) "Great Lakes system" means all the
				  surface waters within the drainage basin of the Great Lakes.
(5) "IC25" means the point estimate of the
				  concentration of a toxic substance, wastewater effluent or other aqueous
				  mixture that would cause a 25% reduction in a nonlethal biological measurement,
				  such as reproduction or growth, of the exposed test organisms in a given time
				  period.
(5m) "IC50" means the point
				  estimate of the concentration of a toxic substance, wastewater effluent or
				  other aqueous mixture that would cause a 50% reduction in a nonlethal
				  biological measurement, such as reproduction or growth, of the exposed test
				  organisms in a given time period.
(6) "IWC" or "Instream waste concentration"
				  means an estimate of the proportion of effluent to total volume of water
				  (receiving water + effluent). The IWC is calculated according to the following
				  equation:
Qe
IWC (as %) = 100 x ---------------
(1 f) Qe +
					 Qs
where:
Qe = effluent flow
f = fraction of the Qe withdrawn
					 from the receiving water
Qs = receiving water flow (in most
					 cases ¼ of a low flow value, such as the Q7,10,
					 is used in order to allow a free zone of passage for aquatic
					 organisms).
(7)
				  "LC50" means the point estimate of the concentration of
				  a toxic substance, wastewater effluent or other aqueous mixture which is lethal
				  to 50% of the exposed organisms in a given time period, when compared to an
				  appropriate control.
(8) "Limit of
				  detection" or "LOD" means the lowest concentration level that can be determined
				  to be significantly different from a blank for that analytical test method and
				  sample matrix.
(9) "Limit of
				  quantitation" or "LOQ" means the concentration of an analyte at which one can
				  state with a degree of confidence for that analytical test method and sample
				  matrix that an analyte is present at a specific concentration on the sample
				  tested.
(11m) "Same waterbody"
				  means hydrologically connected waters of the State with similar water quality
				  characteristics in which a pollutant can travel between in a reasonable period
				  of time without significantly changing chemically or physically. Hydrological
				  connections can include surface and groundwater connections.
(12) "Toxicity test" means a test which
				  determines the toxicity of a chemical substance, wastewater effluent or other
				  aqueous mixture using living organisms. A toxicity test measures the degree of
				  response of exposed test organisms to a chemical substance, wastewater effluent
				  or other aqueous mixture.
(13)
				  "TUa" or "toxic unit acute" means a value that is equal to 100 divided by the
				  LC50 except as provided in s.
				  NR
				  106.08(6) (d).
(13m) "TUc" or "toxic unit chronic" means a
				  value that is equal to 100 divided by the IC25 or the IC50 except as provided
				  in s.
				  NR
				  106.08(6) (d).
(14) "Whole effluent toxicity" or "WET" means
				  the aggregate toxic effect of an effluent as measured directly by a toxicity
				  test.