C. Waterbody Classifications,
Designated Uses, and Attainment: Water quality
standards define the water quality goals of each waterbody or portion thereof,
in part, by designating the use or uses to be made of the water. States adopt
water quality standards to protect public health or welfare, to enhance water
quality, and to serve the purposes of the Clean Water Act: (1) provide,
wherever attainable, water quality for the protection and propagation of fish,
shellfish, and wildlife, as well as, recreation in and on the water and (2)
consider the use and value of State waters for public water supplies,
protection and propagation of fish, shellfish and wildlife, recreation in and
on the water, agriculture and industrial purposes, and navigation.
The State of Mississippi assigns one or more waterbody
classifications to all Surface Waters of the State. Each waterbody
classification has one or more corresponding designated uses. A waterbody, or a
specific waterbody segment, may be assigned multiple waterbody classifications.
When multiple classifications are assigned to a waterbody, the State must
ensure protection of the most sensitive use. The State must also consider the
water quality standards of downstream waters and ensure that its water quality
standards provide for the attainment and maintenance of the water quality
standards of downstream waters. In no case shall it be permissible to deposit
or introduce materials into Surface Waters of the State that will cause
impairment of the designated use(s) of said waters.
Certain Surface Waters of the State may not fall within
desired or prescribed limitations as outlined within these water quality
standards. In such instances, the Commission may authorize exceptions or
alternatives to these criteria as described in more detail within Rule 2.5
Implementation of Water Quality Standards.
H.
Definitions:
(1)
Acute criterion or Criteria Maximum Concentration
(CMC) is the highest concentration of a pollutant to which aquatic
life can be exposed for a short period of time (1-hour average) without
deleterious effects. (
40
CFR
131.36)
(2)
Best management practice
(BMP) means a structural or non-structural management-based
practice used singularly or in combination to reduce nonpoint source inputs to
receiving waters in order to achieve water quality protection goals.
(3)
Bioconcentration factor
(BCF) is defined as the ratio (in L/kg-tissue) of the
concentration of a substance in tissue of an aquatic organism to its
concentration in the ambient water, in situations where the organism is exposed
through the water only and the ratio does not change substantially over time.
(U.S. EPA-822-B-00-004)
(4)
Biological integrity is defined as the ability of a
system to support and maintain a balanced, integrated, and adaptive community
of organisms having a composition, diversity, and functional organization
comparable to that of natural habitats of the region.
(5)
Cancer Potency Factor
(CPF) is a measure of the cancer-causing potency of a substance
estimated by the upper 95 percent confidence limit of the slope of a straight
line calculated by the Linearized Multistage Model according to the U.S. EPA
Guidelines (FR 51(185): 339992-34003, and FR 45(231 Part V);
7931879379).
(6)
Chronic criterion or Criteria Continuous Concentration
(CCC) is the highest concentration of a pollutant to which aquatic
life can be exposed for an extended period of time (4 days) without deleterious
effects. (
40
CFR
131.36)
(7)
Clean techniques
refers to an integrated system of sample collection and laboratory analytical
procedures designed to detect concentrations of trace metals below criteria
levels and eliminate or minimize inadvertent sample contamination that can
occur during traditional sampling practices.
(8)
Composite
sampling is a technique whereby multiple temporally or spatially
discrete media or tissue samples are combined, thoroughly homogenized, and
treated as a single sample.
(9)
E. coli (Escherichia coli) is a
common inhabitant of the intestinal tract of warmblooded animals, and its
presence in water samples is an indication of fecal pollution and the possible
presence of enteric pathogens.
(10)
Enteric
pathogens are a species of bacteria can be highly pathogenic when
they enter and colonize the human digestive tract.
(11)
Existing uses are those uses
actually attained in the waterbody on or after November 28, 1975, whether or
not they are included in the water quality standards.
(12)
Grab samples
are samples where the entire sample is collected in one uninterrupted
interval.
(13) Highest attainable
use is the modified aquatic life, wildlife, or recreation use that is both
closest to the uses specified in section 101(a)(2) of the Clean Water Act and
attainable, based on the evaluation of the factor(s) in § 131.10(g) that
preclude(s) attainment of the use and any other information or analyses that
were used to evaluate attainability. There is no required highest attainable
use where the State demonstrates the relevant use specified in section
101(a)(2) of the Clean Water Act and sub-categories of such a use are not
attainable.
(14)
Mean
Annual Flow is the total of daily mean flows for the full period
of record divided by the total days for the full period of record.
(15)
Membrane Filtration
(MF) is a method of quantitative or qualitative analysis of
bacterial or particulate matter in a water sample filtered through a membrane
capable of retaining bacteria.
(16)
Modified criterion is a waterbody-specific criterion adopted to protect either
the Modified Fish and Wildlife or Drainage Waters classifications. The
criterion should be supported by the findings of the respective waterbody's use
attainability analysis in support of the designated use change and reflect the
use of scientifically defensible methods. Following adoption of modified
criteria into Rule
2.4, the state will submit the modified
criteria for review and require action by the U.S. EPA before the modified
criteria supersede the previously applicable criterion.
(17)
Most probable number
(MPN) is the most probable number of coliform-group organisms per
unit volume of sample water.
(18)
Pollutant minimization program in the context of
40 CFR
131.14, is a structured set of activities to
improve processes and pollutant controls that will prevent and reduce pollutant
loadings.
(19)
Point
source is a stationary location or fixed facility from which
pollutants are discharged or emitted. Also, any single identifiable source of
pollution, e.g., a pipe, ditch, or ship.
(20)
7Q10 is the
average streamflow rate over seven consecutive days that may be expected to be
reached as an annual minimum no more frequently than one year in ten
years.
(21)
7Q2 is the average streamflow rate over seven
consecutive days that may be expected to be reached as an annual minimum no
more frequently than one year in two years.
(22)
Stratification
is the formation of layers of water within a waterbody that are of different
densities. The density difference may be caused by variations of temperature,
salinity, or concentrations of other dissolved substances within the water at
different depths.
(23) Surface
Waters of the State means all waters within the jurisdiction of this state,
including all streams, lakes, ponds, impounding reservoirs, marshes,
watercourses, waterways, wells, springs, irrigation systems, drainage systems,
and all other bodies or accumulations of water, natural or artificial, situated
wholly or partly within or bordering upon the state, and such coastal waters as
are within the jurisdiction of the state, except lakes, ponds or other surface
waters which are wholly landlocked and privately owned, and which are not
regulated under the Clean Water Act (
33 U.S.C.
1251 et seq).
(24)
Threshold odor
number is the number of times a sample needs to be diluted with
clean water in order to reach the level that smell is not detectable.
(25)
Toxic substance
means any substance or combination of substances (including disease-causing
agents), which after discharge and upon exposure, ingestion, inhalation, or
assimilation into any organism, whether directly from the environment or
indirectly by ingestion through food chains, has the potential to cause death,
disease, behavioral abnormalities, cancer, genetic mutations, physiological
malfunctions (including malfunctions or suppression in reproduction or growth)
or physical deformities in such organisms or their offspring.
(26) Use attainability analysis is a
structured scientific assessment of the factors affecting the attainment of a
designated use. This assessment may include physical, chemical, biological, and
economic factors as described in
40 CFR
131.10(g).
(27)
Toxic substance
means any substance or combination of substances (including disease-causing
agents), which after discharge and upon exposure, ingestion, inhalation, or
assimilation into any organism, whether directly from the environment or
indirectly by ingestion through food chains, has the potential to cause death,
disease, behavioral abnormalities, cancer, genetic mutations, physiological
malfunctions (including malfunctions or suppression in reproduction or growth)
or physical deformities in such organisms or their offspring.
(28) Waters of the State means all waters
within the jurisdiction of this state, including all streams, lakes, ponds,
impounding reservoirs, marshes, watercourses, waterways, wells, springs,
irrigation systems, drainage systems, and all other bodies or accumulations of
water, surface and underground, natural or artificial, situated wholly or
partly within or bordering upon the state, and such coastal waters as are
within the jurisdiction of the state, except lakes, ponds or other surface
waters which are wholly landlocked and privately owned, and which are not
regulated under the Clean Water Act (
33 U.S.C.
1251 et seq). Source: Miss. Code Ann. §
49-17-5(1)(f)
(29) Water quality standards variance is a
time-limited designated use and criterion for a specific pollutant(s) or water
quality parameter(s) that reflect the highest attainable condition during the
term of the water quality standards variance.
