Rule 11-6-2.5 - Implementation of Water Quality CriteriaAccording to 40 CFR 131.13, States may, at their discretion, include in their State standards, policies generally affecting their application and implementation, such as mixing zones, low flows and variances. Such policies are subject to U.S. EPA review and approval. If the State adopts a policy applicable only to Surface Waters of the State that are not also Waters of the United States, such policy is not subject to U.S. EPA review and approval.
A.Natural Conditions: Natural conditions are defined as background water quality conditions due only to non-anthropogenic sources. The criteria herein apply specifically with regard to substances attributed to sources (permitted discharges, nonpoint sources, or in-stream activities) as opposed to natural phenomena. Some waterbodies may have characteristics that are naturally outside the limits established herein. Therefore, naturally occurring conditions that preclude attainment of these criteria should not be interpreted as violations of the criteria.B.Applicable Flow: All criteria contained herein shall apply to all stages of stream flow greater than or equal to the 7-day, 10-year minimum flow (7Q10) in unregulated, natural streams, and the legally guaranteed minimum flow in regulated streams, unless otherwise provided in these regulations. This requirement shall not be interpreted to permit any unusual waste discharges during periods of lower flow. Notwithstanding the above, a stream flow equal to the 7-day, 2-year minimum flow (7Q2) in unregulated, natural streams shall be utilized in establishing permit limitations for stormwater permits. In cases in which either (1) the data are indefinite or inconclusive, or (2) the 7-day, 2-year minimum flow and/or the 7-day, 10-year minimum flow are inappropriate because of the hydrology of the area, other appropriate State and federal agencies will be consulted in order to establishing the appropriate and applicable stream flow.
C.Mixing Zones: It is recognized that limited areas of mixing are sometimes unavoidable; however, mixing zones shall not be used as a substitute for waste treatment. Mixing zones constitute an area whereby physical mixing of a wastewater effluent with a receiving waterbody occurs. Application of mixing zones shall be made on a case-by-case basis and shall only occur in cases involving large surface waterbodies in which a long distance or large area is required for the wastewater to completely mix with the receiving waterbody. The location of a mixing zone shall not significantly alter the designated uses of the receiving water outside its established boundary. Adequate zones of passage for the migration and free movement of fish and other aquatic biota shall be maintained. Toxicity and human health concerns within the mixing zone shall be addressed as specified in the U.S. EPA Technical Support Document for Water Quality-Based Toxics Control (U.S. EPA-505/2-90-001, March 1991) and amendments thereof. Under no circumstances shall mixing zones overlap or cover tributaries, nursery locations, locations of threatened or endangered species, or other ecologically sensitive areas.
D. Schedules of Compliance: When appropriate, the State, UIC, or NPDES permit issued by the Permit Board pursuant to Rule 1.1.3.H may contain a schedule of compliance leading to compliance with the Federal Water Pollution Control Act and the Mississippi Air and Water Pollution Control Law. Additional information and requirements regarding schedules of compliance can be found within 11 Miss. Admin. Code Pt. 6, R. 1.1.4.A(9).
E. Water Quality Standards Variances: As defined in 40 CFR 131.3(o), a 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 variance. A water quality standards variance must meet certain provisions according to 40 CFR 131.14 and must meet certain public participation requirements within 40 CFR 131.20(b). A WQS variance is a water quality standard subject to U.S. EPA review and approval or disapproval. MDEQ will apply the same provisions of 40 C.F.R. § 131.14 in considering a WQS variance for State waters that do not meet the definition of Waters of the United States and will use the same public participation requirements within § 131.20(b) for such waters. A WQS variance to Surface Waters of the State which do not meet the definition of "Waters of the United States" will not be subject to U.S. EPA review and approval or disapproval.
(1) Applicability: (a) A WQS variance may be adopted for a permittee(s) or waterbody/waterbody segment(s), but only applies to the permittee(s) or waterbody/waterbody segment(s) specified in the WQS variance.(b) Where the State adopts a WQS variance, the State must retain, in its standards, the underlying designated use and criterion addressed by the WQS variance, unless the State adopts and U.S. EPA approves a revision to the underlying designated use and criterion consistent with 40 CFR 131.10 and 131.11. All other applicable standards not specifically addressed by the WQS variance remain applicable. U.S. EPA approval is not required for State waters that are not waters of the United States.(c) A WQS variance, once adopted by the State and approved by U.S. EPA, shall be the applicable standard for purposes of the Clean Water Act under 40 CFR 131.21(d) through (e), for the following limited purposes. An approved WQS variance applies for the purposes of developing NPDES permit limits and requirements under 301(b)(1)(C), where appropriate, consistent with paragraph (1)(a) of this section. States and other certifying entities may also use an approved WQS variance when issuing certifications under section 401 of the Clean Water Act. U.S. EPA approval is not required for Surface Waters of the State that are not Waters of the United States.(d) The State may not adopt WQS variances if the designated use and criterion addressed by the WQS variance can be achieved by implementing technology-based effluent limits required under sections 301(b) and 306 of the Clean Water Act.(2) Requirements for Submission to the Commission and/or to U.S EPA: (a) A WQS variance must include: (i) Identification of the pollutant(s) or water quality parameter(s), and the waterbody or waterbody segment(s) to which the WQS variance applies. Discharger(s)-specific WQS variances must also identify the permittee(s) subject to the WQS variance.(ii) The requirements that apply throughout the term of the WQS variance. The requirements shall represent the highest attainable condition of the waterbody or waterbody segment applicable throughout the term of the WQS variance based on the documentation required in (2)(b) of this section. The requirements shall not result in any lowering of the currently attained ambient water quality, unless a WQS variance is necessary for restoration activities, consistent with paragraph (2)(b)(i)(1) of this section. The State must specify the highest attainable condition of the waterbody or waterbody segment as a quantifiable expression that is one of the following:(1) For discharger(s)-specific WQS variances: The highest attainable interim criterion; or
The interim effluent condition that reflects the greatest pollutant reduction achievable; or
If no additional feasible pollutant control technology can be identified, the interim criterion or interim effluent condition that reflects the greatest pollutant reduction achievable with the pollutant control technologies installed at the time the State adopts the WQS variance, and the adoption and implementation of a pollutant minimization program.
(2) For WQS variances applicable to a waterbody or waterbody segment: The highest attainable interim use and interim criterion; or
If no additional feasible pollutant control technology can be identified, the interim use and interim criterion that reflect the greatest pollutant reduction achievable with the pollutant control technologies installed at the time the State adopts the WQS variance, and the adoption and implementation of a pollutant minimization program.
(iii) A statement providing that the requirements of the WQS variance are either the highest attainable condition identified at the time of the adoption of the WQS variance, or the highest attainable condition later identified during any re-evaluation consistent with paragraph (2)(a)(v) of this section, whichever is more stringent.(iv) The term of the WQS variance, expressed as an interval of time from the date of Commission and/or U.S. EPA approval or a specific date. The term of the WQS variance must only be as long as necessary to achieve the highest attainable condition and consistent with the demonstration provided in paragraph (2)(b) of this section. The State may adopt a subsequent WQS variance consistent with this section.(v) For a WQS variance with a term greater than five years, a specified frequency to re-evaluate the highest attainable condition using all existing and readily available information and a provision specifying how the State intends to obtain public input on the re-evaluation. Such re-evaluations must occur no less frequently than every five years after Commission and/or U.S. EPA approval of the WQS variance and the results of such re-evaluation must be submitted to the Commission and/or U.S EPA within 30 days of completion of the re-evaluation.(vi) A provision that the WQS variance will no longer be the applicable water quality standard for purposes of the Clean Water Act if the State does not conduct a re-evaluation consistent with the frequency specified in the WQS variance or the results are not submitted to the Commission and/or U.S. EPA as required by (2)(a)(v) of this section.(b) The supporting documentation must include:(i) Documentation demonstrating the need for a WQS variance. (1) For a WQS variance to a use specified in section 101(a)(2) of the Clean Water Act or a sub-category of such a use, the State must demonstrate that attaining the designated use and criterion is not feasible throughout the term of the WQS variance because: One of the factors listed in 40 CFR 131.10(g) is met, or
Actions necessary to facilitate lake, wetland, or stream restoration through dam removal or other significant reconfiguration activities preclude attainment of the designated use and criterion while the actions are being implemented.
(2) For a WQS variance to a non-101(a)(2) use, the State must submit documentation justifying how its consideration of the use and value of the water for those uses listed in 40 CFR 131.10(a) appropriately supports the WQS variance and term. A demonstration consistent with paragraph (2)(b)(i)(1) of this section may be used to satisfy this requirement.(ii) Documentation demonstrating that the term of the WQS variance is only as long as necessary to achieve the highest attainable condition. Such documentation must justify the term of the WQS variance by describing the pollutant control activities to achieve the highest attainable condition, including those activities identified through a Pollutant Minimization Program, which serve as milestones for the WQS variance.(iii) In addition, for a WQS variance that applies to a waterbody or waterbody segment: Identification and documentation of any cost-effective and reasonable best management practices for nonpoint source controls related to the pollutant(s) or water quality parameter(s) and waterbody or waterbody segment(s) specified in the WQS variance that could be implemented to make progress towards attaining the underlying designated use and criterion. The State must provide public notice and comment for any such documentation.
Any subsequent WQS variance for a waterbody or waterbody segment must include documentation of whether and to what extent best management practices for nonpoint source controls were implemented to address the pollutant(s) or water quality parameter(s) subject to the WQS variance and the water quality progress achieved.
(3) Implementing WQS variances in NPDES permits. A WQS variance serves as the applicable water quality standard for implementing NPDES permitting requirements for the term of the WQS variance. Any limitations and requirements necessary to implement the WQS variance shall be included as enforceable conditions of the NPDES permit for the permittee(s) subject to the WQS variance.
F. Designation of Uses and Use Attainability Analyses:(1)According to 40 CFR 131.10(a), the Commission will specify appropriate water uses to be achieved and protected. The classification of Surface Waters of the State must take into consideration the use and value of water for public water supplies, protection and propagation of fish, shellfish and wildlife, recreation in and on the water, agricultural, industrial, and other purposes including navigation. If adopting new or revised designated uses other than the uses specified in section 101(a)(2) of the Clean Water Act, or removing designated uses, the State must submit documentation justifying how its consideration of the use and value of water for those uses listed in this paragraph appropriately supports the State's action. A use attainability analysis may be used to satisfy this requirement. In no case shall the State adopt waste transport or waste assimilation as a designated use. The State shall also re-examine any waterbody segment with water quality standards that do not include the uses specified in section 101(a)(2) of the Clean Water Act every 3 years to determine if any new information has become available. If such new information indicates that the uses specified in section 101(a)(2) of the Clean Water Act are attainable, the State shall revise its standards accordingly.(2) In designating uses of a waterbody and the appropriate criteria for those uses, the State shall take into consideration the water quality standards of downstream waters and shall ensure that its water quality standards provide for the attainment and maintenance of the water quality standards of downstream waters.(3) The State may adopt sub-categories of a use and set the appropriate criteria to reflect varying needs of such sub-categories of uses, for instance, to differentiate between cold water and warm water fisheries.(4) At a minimum, uses are deemed attainable if they can be achieved by the imposition of effluent limits required under sections 301(b) and 306 of the Clean Water Act and costeffective and reasonable best management practices for nonpoint source control.(5) The State may adopt seasonal uses as an alternative to reclassifying a waterbody or segment thereof to uses requiring less stringent water quality criteria. If seasonal uses are adopted, water quality criteria should be adjusted to reflect the seasonal uses, however, such criteria shall not preclude the attainment and maintenance of a more protective use in another season.(6) The State may designate a use, or remove a use that is not an existing use, if the State conducts a use attainability analysis that demonstrates attaining the use is not feasible because of one of the six factors in this paragraph. If the State adopts a new or revised water quality standard based on a required use attainability analysis, the State shall also adopt the highest attainable use. (a) Naturally occurring pollutant concentrations prevent the attainment of the use; or(b) Natural, ephemeral, intermittent or low flow conditions or water levels prevent the attainment of the use, unless these conditions may be compensated for by the discharge of sufficient volume of effluent discharges without violating State water conservation requirements to enable uses to be met; or(c) Human caused conditions or sources of pollution prevent the attainment of the use and cannot be remedied or would cause more environmental damage to correct than to leave in place; or(d) Dams, diversions or other types of hydrologic modifications preclude the attainment of the use, and it is not feasible to restore the waterbody to its original condition or to operate such modification in a way that would result in the attainment of the use; or(e) Physical conditions related to the natural features of the waterbody, such as the lack of a proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water quality, preclude attainment of aquatic life protection uses; or(f) Controls more stringent than those required by sections 301(b) and 306 of the Clean Water Act would result in substantial and widespread economic and social impact.(7) The State may not remove designated uses if:(a) They are existing uses, as defined in 40 CFR 131.3, unless a use requiring more stringent criteria is added; or(b) Such uses will be attained by implementing effluent limits required under sections 301(b) and 306 of the Clean Water Act and by implementing cost-effective and reasonable best management practices for nonpoint source control.(8) Where existing water quality standards specify designated uses less than those which are presently being attained, the State shall revise its standards to reflect the uses actually being attained.(9) The State must conduct a use attainability analysis as described in 40 CFR 131.3(g), and paragraph (F)(5) of this section, whenever:(a) The State designates for the first time, or has previously designated for a waterbody, uses that do not include the uses specified in section 101(a)(2) of the Clean Water Act; or(b) The State wishes to remove a designated use that is specified in section 101(a)(2) of the Clean Water Act, to remove a sub-category of such a use, or to designate a sub-category of such a use that requires criteria less stringent than previously applicable.(10) The State is not required to conduct a use attainability analysis whenever:(a) The State designates for the first time, or has previously designated for a waterbody, uses that include the uses specified in section 101(a)(2) of the Clean Water Act; or(b) The State designates a sub-category of a use specified in section 101(a)(2) of the Clean Water Act that requires criteria at least as stringent as previously applicable; or(c) The State wishes to remove or revise a designated use that is a non-101(a)(2) use. In this instance, as required by paragraph (1) of this section, the State must submit documentation justifying how its consideration of the use and value of water for those uses listed in paragraph (1) appropriately supports the State's action, which may be satisfied through a use attainability analysis.
Miss. Code Ann. §§ 49-2-9, 49-2-1, et seq., and 49-17-1, et seq.