Current through Register Vol. XLI, No. 40, October 4, 2024
Section 60-5-6 - Tier 3 Protection Review Procedures (Outstanding National Resource Waters). See 47 CSR 2-4.1.c and 47 CSR 2-2.10 for a Description of Outstanding National Resource Waters (ONRW)6.1. Tier 3 waters. ONRWs are to be maintained, protected and improved where necessary. Any proposed new or expanded regulated activity that would degrade (result in a lowering of water quality) a water body that has been designated an ONRW, other than temporary lowering of water quality, is prohibited.6.2. Tier 3 antidegradation review. The agency shall use the following antidegradation implementation procedures for evaluating new or expanded regulated activities that have the potential to affect Outstanding National Resource Waters (ONRWs), as described in 47 CSR 2 - 4.1.c. and as listed in accordance with subsection 7.1. 6.2.a. Determine whether the proposed activity is short term in nature and the resulting changes in water quality will be temporary. Such determination will be made on a case-by-case basis and shall be made after consideration of the following factors: 6.2.a.1. The length of time during which the water quality will be lowered;6.2.a.2. The percent change in ambient concentrations;6.2.a.3. The parameters affected;6.2.a.4. The likelihood for long-term water quality benefits to the segment (e.g., as may result from dredging of contaminated sediments);6.2.a.5. The degree to which achieving applicable water quality standards during the proposed activity may be at risk; and6.2.a.6. The potential for any residual long-term influences on existing uses.6.2.b. If after review of the factors in paragraphs 6.2.a.1 through 6.2.a.6, the agency determines that the proposed activity will be short term in nature and the changes in water quality will be temporary and limited, the proposed activity may be authorized. In such case the antidegradation review findings shall be documented and public notice activities shall be initiated. If after review of the factors in paragraphs 6.2.a.1 through 6.2.a.6. the agency determines that the proposed activity will not be short term in nature or that changes in water quality will not be temporary and limited, the proposed activity shall be denied.6.3. Sources upstream from an ONRW. Any proposed activity that would result in a permanent new or expanded discharge upstream of an ONRW segment is prohibited except where such source would improve or not degrade the existing water quality of the downstream ONRW segment.6.3.a. To determine whether the proposed activity will result in the lowering of water quality in the downstream ONRW segment, the following factors, when applicable, shall be considered:6.3.a.1. Change in ambient concentrations predicted at the appropriate critical condition(s);6.3.a.2. Change in loadings (i.e., the new or expanded loadings compared to total existing loadings to the segment);6.3.a.3. Reduction in available assimilative capacity;6.3.a.4. Nature, persistence and potential effects of the parameter;6.3.a.5. Potential for cumulative effects;6.3.a.6. Degree of confidence in the various components of any modeling technique utilized (e.g., degree of confidence associated with the predicted effluent variability); and6.3.a.7. Other factors determined by the Secretary, when appropriate.6.3.b. If a preliminary determination is made that the applicable criteria in paragraphs 6.3.a.1. through 6.3.a.7. will be met, the antidegradation review findings shall be documented and the applicable public notice activities shall be initiated. If after review of the factors in paragraphs 6.3.a.1. through 6.3.a.7., the Secretary determines that the proposed activity will result in the lowering of water quality in the downstream ONRW stream segment, the proposed activity shall be denied.6.4. For ONRWs in areas designated as federal Wilderness, nothing in this rule is intended to authorize activities not authorized by the Wilderness Act.6.5. A proposed activity that will result in a new or expanded discharge in a water subject to Tier 3 protection may be allowed where the applicant agrees to implement or finance upstream controls of point or nonpoint sources sufficient to offset the water quality effects of the proposed activity from the same parameters and insure an improvement in water quality as a result of the trade. The basis of the trade will be documented and will be consistent with the trading assessment procedure that has been approved by the Secretary. A trade may be made between more than one stream segment where removing a discharge in one stream segment directly results in improved water quality in another stream segment. In addition, (1) the effluent trade must be for the same parameter; (2) where uncertainty exists regarding the effluent trade, an adequate margin of safety will be required; (3) dischargers cannot claim offsets for water quality improvements that are required or will occur irrespective of the proposed new or expanded discharge; and (4) the trade must be enforceable.