In addition to the meanings provided in the Water Quality
Control Act (T.C.A. §
terms used in these rules shall mean the following:
(1) Atypical consumers - Those persons in the
vicinity of a stream or lake who due to physiological factors or previous
exposure are more sensitive to specific pollutants than is the population in
general. Examples of atypical consumers may include, but are not limited to:
children; pregnant or nursing women; subsistence fishermen; frequent purchasers
of commercially harvested fish; and agricultural, industrial, or military
personnel who may have had previous occupational exposure to the contaminant of
(2) Conventional water
treatment - Conventional water treatment as referred to in the criteria denotes
coagulation, sedimentation, filtration, and chlorination or
(3) Degradation - The
alteration of the properties of waters by the addition of pollutants,
withdrawal of water, or removal of habitat, except those alterations of a short
degradation - Degradation of a small magnitude, as provided in this paragraph.
Discharges and withdrawals
Subject to the limitation in part 3. of
this subparagraph, a single discharge will be considered de minimis if it uses
less than five percent of the available assimilative capacity for the substance
(Note: Consistent with T.C.A. §
special consideration will be given to bioaccumulative substances to confirm
the effect is de minimis, even if they are less than five percent of the
available assimilative capacity.)
2. Subject to the limitation in part 3. of
this subparagraph, a single water withdrawal will be considered de minimis if
it removes less than five percent of the 7Q10 flow of the stream.
3. If more than one activity described in
part 1. or 2. of this subparagraph has been authorized in a segment and the
total of the authorized and proposed impacts uses no more than 10% of the
assimilative capacity, or 7Q10 low flow, they are presumed to be de minimis.
Where the total of the authorized and proposed impacts uses 10% of the
assimilative capacity, or 7Q10 low flow, additional degradation may only be
treated as de minimis if the Division finds on a scientific basis that the
additional degradation has an insignificant effect on the resource.
(b) Habitat alterations authorized
by an Aquatic Resource Alteration Permit (ARAP) are de minimis if the Division
finds that the impacts, individually and cumulatively are offset by impact
minimization and/or in-system mitigation, provided however, in ONRWs the
mitigation must occur within the ONRW.
(5) Domestic wastewater discharge - A
discharge of sanitary and other non-process wastewater from a treatment
facility other than a publicly-owned treatment works (POTW) treating municipal
sewage and/or industrial waste. Examples of domestic wastewater discharges
include, but are not limited to, homes, subdivisions, campgrounds, hotels,
travel centers, parks, and schools.
(6) Ecoregion - A relatively homogeneous area
defined by similarity of climate, landform, soil, potential natural vegetation,
hydrology, or other ecologically relevant variables.
(7) Epilimnion - The upper layer of water in
a thermally stratified lake or reservoir. This layer consists of the warmest
water and has a fairly uniform (constant) temperature.
(8) Groundwater - Water beneath the surface
of the ground within the zone of saturation, whether or not flowing through
known and definite channels.
Groundwater table - The upper surface of the zone of saturation by ground
(10) Hypolimnion - The
lowest layer in a thermally stratified lake or reservoir. This layer consists
of colder, more dense water, has a constant temperature and no mixing occurs.
The hypolimnion of a eutrophic lake is usually low or lacking in
(11) Interflow - The runoff
infiltrating into the surface soil and moving toward streams as shallow,
perched water above the main groundwater level.
(12) In-system mitigation - Mitigation for
habitat alterations sufficient to result in no overall net loss of resource
values, if provided in the same eight-digit hydrologic unit code as the
alteration, or in another area proximate to the alteration as approved by the
Division to offset the loss of resource values in the area. In-system
mitigation may not occur within a different major river drainage basin as the
alteration (i.e., Tennessee River, Cumberland River,
(13) Lentic -
Still water aquatic ecosystems such as ponds, lakes, or reservoirs.
(14) Lotic - Flowing water aquatic ecosystems
such as streams and rivers.
Measurable degradation, as used in the context of discharges or withdrawals -
Changes in parameters of waters that are of sufficient magnitude to be
detectable by the best available instrumentation or laboratory analyses.
(Note: Because analytical techniques change, the Department may consider
either the most sensitive detection method needed to comply with State
standards or any biological, chemical, physical, or analytical method,
conducted in accordance with EPA approved methods as identified in 40 C.F.R.
part 136. Consistent with T.C.A. §
scenarios involving cumulative, non-measurable activities or parameters that
are managed by a narrative criterion, the Department will use mathematical
models and ecological indices to ensure no degradation will result from the
authorization of such activities, consistent with the State's mixing zone
(ML) - A term referring to the lowest sample concentration at which reliable
quantitative measurements can be made as defined in Appendix A of 40 C.F.R.
(17) Mixing zone -
That section of a flowing stream or impounded waters in the immediate vicinity
of an outfall where an effluent becomes dispersed and mixed.
(18) Multiple populations - Two or more
individuals from each of two or more distinct taxa, in the context of obligate
lotic aquatic organisms.
or increased discharge - A new discharge of pollutants to waters of the state
or an increase in the authorized loading of a pollutant above either (1)
numeric effluent limitations established in a National Pollutant Discharge
Elimination System permit for that discharge, or (2) if no such limitations
exist, the actual discharges of that pollutant.
(20) Normal weather conditions - Those within
one standard deviation of the cumulative monthly precipitation means for at
least the three months prior to the hydrologic determination investigation,
based on a 30-year average computed at the end of each decade. Precipitation
data shall come from National Oceanographic and Atmospheric Agency's National
Climatic Data Center, National Resources Conservation Service's National
Climatic Data Center, Natural Resources Conservation Service's National Water
and Climate Center, or other well-established weather station.
(21) Obligate lotic aquatic organisms -
Organisms that require flowing water for all or almost all of the aquatic phase
of their life cycles.
Parameter - A biological, chemical, radiological, bacteriological, or physical
property of water that can be directly measured. Some criteria are expressed in
terms of a single parameter; others, such as habitat, nutrients, and biological
integrity are not directly measured, but are derived from measurements of
(23) Perched water -
Water that accumulates above an aquitard that limits downward migration where
there is an unsaturated interval below it, between the aquitard and the zone of
(24) Photic zone - The
region of water through which light penetrates and where photosynthetic
condition - A parameter-specific set of data from regional reference sites that
establish the statistical range of values for that particular substance at
Reference site - Least impacted waters within an ecoregion that have been
monitored to establish a baseline to which alterations of other waters can be
Resource values -
The physical, chemical, and biological properties of the water resource that
help maintain classified uses. These properties may include, but are not
limited to, the ability of the water resource to:
(a) Filter, settle, and/or eliminate
(b) Prevent the entry
of pollutants into downstream waters;
(c) Assist in flood prevention;
(d) Provide habitat for fish, aquatic life,
(e) Provide drinking
water for wildlife and livestock;
(f) Provide and support recreational and
navigational uses; and
both safe quality and adequate quantity of water for domestic water supply and
other applicable classified uses.
(28) Response variable - A characteristic of
water quality that can be measured and changes as a result of an alteration of
habitat, water withdrawal, or discharge of pollutants, as distinguished from
agents that cause changes in aquatic systems.
(29) Significant degradation - An appreciable
permanent loss of resource values resulting from a habitat alteration in a
waterbody with unavailable parameters for habitat, unless mitigation sufficient
to ensure no overall net loss of resource values is provided.
(30) Stratification - The tendency in lakes
and reservoirs for distinct layers of water to form as a result of vertical
change in temperature and, therefore, in the density of water. During
stratification, dissolved oxygen, nutrients, and other parameters of water
chemistry do not mix well between layers, establishing chemical as well as
(31) Stream - A
surface water that is not a wet weather conveyance.
(32) Subecoregion - A smaller, more
homogenous area that has been delineated within an ecoregion.
(33) Thermocline - The middle layer in a
thermally stratified lake or reservoir. In this layer there is a rapid decrease
in temperature with depth. Also called the metalimnion.
(34) Wadeable streams - Streams that can be
sampled using a hand held, one meter square or smaller kick net without water
and materials escaping over the top of the net.
(35) Watercourse - A man-made or natural
hydrologic feature with a defined linear channel which discretely conveys
flowing water, as opposed to sheet-flow.
Wet weather conveyance - Man-made or
natural watercourses, including natural watercourses that have been modified by
(a) That flow only in direct
response to precipitation runoff in their immediate locality;
(b) Whose channels are at all times above the
(c) That are not
suitable for drinking water supplies; and
(d) In which hydrological and biological
analyses indicate that, under normal weather conditions, due to naturally
occurring ephemeral or low flow there is not sufficient water to support fish,
or multiple populations of obligate lotic aquatic organisms whose life cycle
includes an aquatic phase of at least two months.
(37) Wet weather conveyance determination -
The decision based on site specific information of whether a particular
watercourse is a stream or a wet weather conveyance. It is synonymous with
"stream determination" and "hydrologic determination."
(38) Zone of saturation - A subsurface zone
below the groundwater table in which all of the interconnected voids and pore
spaces are filled with water.