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011 - <br />November 1, 2018 <br />Page 2 <br />The Division explains (page three, Table 2, and first full paragraph) that total dissolved solids <br />(TDS) values used for this review of the 2017 AHR are a guideline, and the Division cites academic <br />literature sources to support this guideline. Academic literature cited and the guidelines described are not <br />an applicable regulatory mechanism to evaluate TDS values. Rather, the Water Quality Control <br />Commission's statewide and site-specific surface and ground water standards in Regulations 37 (surface <br />water), 41 (statewide groundwater) and 42 (site-specific groundwater) are the appropriate standards to <br />use. Pursuant to statute and the Memorandum of Agreement for the Implementation of SB 181 <br />Amendments to the Colorado Water Quality Control Act (25-8-101, et seq) Pertaining to the Regulation <br />of Mineral Mines, the Water Quality Control Commission is solely responsible for the adoption of water <br />quality standards and classifications for surface water and ground water. <br />Further, the Division used recent discharge monitoring reports (DMR) to assess sources of TDS <br />(page four, second full paragraph). Mine discharges to surface waters are regulated under the Clean Water <br />Act, with discharge permits issued and enforced by the Colorado Department of Public Health and <br />Environment, Water Quality Control Division (WQCD). The MOA pertaining to the Regulation of <br />Mineral Mines recognized that the WQCD is solely responsible for issuance and enforcement of permits <br />authorizing point source discharges to surface waters. These WQCD permits implement Colorado's <br />surface water use classifications and standards, including the Colorado River Salinity (TDS) Standards in <br />Regulation 39. <br />Finally, the Division noted a typographical error on Exhibit 1A, which will be corrected on <br />further AHR submittals. <br />Surface Water <br />The Division remarks that discharges from Colowyo are a source of TDS for Taylor and Good <br />Spring Creeks. As described above, discharges from the Colowyo Mine are regulated under Colowyo's <br />CDPS Permit No. CO -0045161. Discharges that have occurred under the discharge permit are compliant <br />with all effluent limitations and conditions, including all salinity -related limits. <br />Groundwater <br />Tri-State refers the Division to "Points of Compliance Evaluation For Alluvial Groundwater in <br />the Taylor, Wilson, and Good Springs Creek Drainages at the Colowyo Mine, Meeker, Colorado" <br />(Peterson 2015), and "Colowyo Mine Points of Compliance Evaluation " (AECOM 2018) submitted to the <br />Division under TR -125. Both reports provide a detailed analysis of groundwater monitoring results, a <br />thorough discussion of the data, and the projected impacts in relation to the PHC within the mining permit <br />for Colowyo. <br />If you should have any additional questions or concerns, please feel free to contact Tony <br />Tennyson at (970) 824-1232 at your convenience. <br />AN EQUAL OPPORTUNITY/AFFIRMATIVE ACTION EMPLOYER <br />A Touchstone Energy'Cooperative t <br />