Current through Register Vol. 48, No. 9, September 27, 2024
1. The
water quality standards are applicable to both surface waters and ground
waters.
2. Any exception specified
in this regulation is to be applied exclusively to the situation for which it
was incorporated and not as a general rule applicable to all situations or
waters of the State.
3. Uses in all
waters shall be protected, wherever attainable, regardless of flow and
classification of waters.
4.
Critical flows for determining permit effluent limitations and/or permit
conditions or requirements, including permit development such as wasteload
allocations or load allocations in total maximum daily loads (TMDLs), will be
calculated in accordance with the following:
a. Aquatic life numeric criteria.
(1) The applicable critical flow conditions
for aquatic life criteria shall be defined as 7Q10 or tidal conditions as
determined by the Department. The numeric criteria of this regulation are not
applicable to waters of the State when the flow rate is less than 7Q10 except
as prescribed below.
(2) The
Department shall consider conditions that are comparable to or more stringent
than 7Q10 where appropriate to protect classified and existing uses, such as
below dams and in tidal situations. Only those situations where the use of 7Q10
flows are determined to be impracticable, inappropriate, or insufficiently
protective of aquatic life uses shall be considered as a situation in which the
Department may consider other flow conditions.
(3) NPDES permit conditions shall be based on
a critical condition analysis (e.g., critical flow, temperature or pH, or a
combination of factors which would represent a critical condition). The
Department may consider less stringent limits based on a critical ambient water
temperature during November through February.
b. Human health and organoleptic numeric
criteria.
(1) The applicable critical flow
conditions for human health shall be defined as annual average flow for
carcinogens, 7Q10 (or 30Q5 if provided by the applicant) for noncarcinogens, or
tidal conditions as determined by the Department. The applicable critical flow
conditions for organoleptic criteria shall be defined as annual average flow or
tidal conditions as determined by the Department. The numeric criteria of this
regulation are not applicable to waters of the State when the flow rate is less
than the annual average flow for carcinogens or 7Q10 (or 30Q5 if provided by
the applicant) for noncarcinogens, except as prescribed below.
(2) The Department shall consider conditions
that are comparable to or more stringent than annual average flow, 7Q10, or
30Q5 (if provided by the applicant) where appropriate to protect the classified
and existing uses, such as below dams and in tidal situations. Only those
situations where the use of annual average flow, 7Q10, or 30Q5 (if provided by
the applicant) are determined to be impracticable, inappropriate, or
insufficiently protective of human health uses shall be considered as a
situation in which the Department may consider other flow conditions.
c. As described below,
the Department may also consider conditions other than 7Q10 for use with an
HCR.
(1) After a complete antidegradation
review in compliance with Section D.2., an HCR for oxygen-demanding substances
may be permitted by the Department for the following situations:
i. If other flow-related effluent conditions
are allowed by federal effluent guidelines as specified in
40 CFR Parts
400-499 (Chapter I, Subchapter N) and
when used the numeric criteria shall not be exceeded and all water quality
standards are maintained and protected;
ii. For industrial discharges, after
application of advanced wastewater treatment, as determined by the Department,
for the type of wastewater discharged;
iii. For other discharges, after application
of advanced wastewater treatment which will be defined, for this purpose, at or
below the following permit effluent limitations of BOD5
= 10 mg/L, NH3-N = 1 mg/L, and DO = 6 mg/L.
(2) In cases where an HCR may be
allowed, the permit effluent limitations for toxics will not be variable and
will be based on the critical flow conditions (chemical-specific or
WET).
(3) In cases where an HCR may
be allowed, new or proposed expansions of existing permits shall require
instream biological assessments and existing permits may require instream
biological assessments.
5. Intermittent streams and ephemeral streams
shall be considered waters of the State. The water quality standards of the
class of the stream to which intermittent and ephemeral streams are tributary
shall apply, disregarding any site-specific numeric criteria for the named
waterbody. This does not preclude the development of site-specific numeric
criteria for intermittent and ephemeral streams.
6. The standards of adjacent waters must be
maintained in basins excavated from high ground and constructed solely for
berthing vessels. The standards of the adjacent waters must also be maintained
with regard to impacts from created marina basins.
7. The existing and classified uses of
downstream waters shall be maintained and protected and existing uses shall be
protected regardless of the classification of the downstream waters. In
tidally-influenced waters, the existing and classified uses of both upstream
and downstream waters shall be maintained and protected and the existing uses
shall be protected regardless of the classification of the upstream and
downstream waters.
8. Where surface
waters are not classified by name (unlisted) in R.61-69, Classified Waters, the
water quality standards of the class of the stream to which they are tributary
shall apply, disregarding any site-specific numeric criteria for the named
waterbody. In tidal areas where an unlisted tributary may affect or flows
between two (2) differently classified waterbodies, regardless of whether the
location is upstream or downstream, the more stringent numeric criteria of the
classified waters apply to the unlisted tributary, disregarding any
site-specific numeric criteria for those waterbodies. This does not preclude
the development of site-specific numeric criteria for unlisted
tributaries.
9. Because of natural
conditions some surface and ground waters may have characteristics outside the
standards established by this regulation. Such natural conditions do not
constitute a violation of the water quality standards; however, degradation of
existing water quality is prohibited unless consistent with Section D.4. of
this regulation.
10. A mixing zone
for surface waters may be allowed by the Department. All water quality
standards of the classification of the surface waters, including affected
downstream waters, are applicable unless a mixing zone, setting forth certain
conditions, is granted by the Department. When the Department grants a mixing
zone, the mixing zone shall not be an area of waste treatment, nor shall it
interfere with or impair the existing uses of the waterbody. The size of the
mixing zone shall be minimized, as determined by the Department, and shall be
based upon applicable critical flow conditions. Since mixing zones are
allocated impact zones where human health and aquatic life numeric criteria can
be exceeded, the Department shall restrict their use. The following
prohibitions and restrictions are established in order to support these
important uses of the waters of the State.
a.
In order to protect human health, mixing zones are not allowed when: they would
endanger public health and welfare, the mixing zone would adversely affect
shellfish harvesting, or the mixing zone would be for bacteria (e.g., fecal
coliform).
b. In order to protect
aquatic life, mixing zones are not allowed when: a pollutant, excluding
temperature or thermal, in a discharge would attract biota; the mixing zone
would result in undesirable aquatic organisms or a dominance of nuisance
species outside of the mixing zone; there is a reasonable expectation that a
discharge would adversely affect a federally-listed endangered or threatened
aquatic species, its habitat, or a proposed or designated critical habitat; the
mixing zone would not allow safe passage of aquatic organisms when passage
would otherwise be unobstructed; or the mixing zone would not allow for the
protection and propagation of a balanced indigenous aquatic community in and on
the water body.
c. In order to
protect both human health and aquatic life, mixing zones are not allowed when:
a discharge would not be predicted to or does not produce adequate mixing at
the point of discharge; or a discharge would be to a waterbody where multiple
discharges interact if the combined mixing zone would impair the waterbody
outside the mixing zone. The Department may prohibit or limit mixing zones in
waters of the State that may be considered a significant estuarine nursery
habitat for resident species.
d.
The size of the mixing zone shall be kept to a minimum and may be determined on
an individual project basis considering biological, chemical, engineering,
hydrological, and physical factors.
11. Mixing zones for ground waters may be
allowed by the Department. In order to ensure the maintenance and protection of
the uses of the waters of the State and in compliance with Section D of this
regulation, any mixing zone granted by the Department shall be determined on an
individual basis by the Department as prescribed below.
a. The numeric standards for Class GB ground
water, Section H.9., are applicable unless a mixing zone solely within the
bounds of the property, setting forth certain conditions, is granted by the
Department. Such a mixing zone shall be granted upon satisfactory demonstration
to the Department that:
(1) Reasonable
measures have been taken or binding commitments are made to minimize the
addition of contaminants to ground water and/or control the migration of
contaminants in ground water;
(2)
The ground water in question is confined to a shallow geologic unit which has
little or no potential of being an Underground Source of Drinking Water, and
discharges or will discharge to surface waters without contravening the surface
water standards set forth in this regulation;
(3) The contaminant(s) in question occurs
within the bounds of the property, and there is minimum possibility for ground
water withdrawals (present or future) to create drawdown such that contaminants
would flow off-site; and
(4) The
contaminants or combination of contaminants in question are not dangerously
toxic, mobile, or persistent.
b. [Reserved].
12. Site-specific numeric criteria for
surface waters may be established by the Department to replace the numeric
criteria of Sections E, G, and the appendix of this regulation or to add new
numeric criteria not contained in this regulation. Establishment of such
numeric criteria shall be subject to public participation and administrative
procedures for adopting regulations. In addition, such site-specific numeric
criteria shall not apply to tributary or downstream waters unless specifically
described in the water classification listing in R.61-69, Classified
Waters.
13. In classifying and
adopting standards for the waters of the State, the Department considers:
a. The size, depth, surface area covered,
volume, flow direction, rate of flow, stream gradient, and temperature of the
water;
b. The character of the
district bordering such water and its suitability for the uses and with a view
to conserving it and encouraging the most appropriate use of the lands
bordering on such water for residential, agricultural, industrial, or
recreational purposes;
c. The uses
which have been made, are being made, may be made or are desired to be made of
such waters for transportation, domestic, and industrial consumption,
irrigation, swimming, fishing, fish culture, fire prevention, sewage disposal,
or other uses;
d. The present
quality of such waters; and e. Information, about the four (4) items above,
from government agencies, interested groups, and the public.
