Laserfiche WebLink
d) An additional mass balance analysis is requested, and should be <br />included in Section 4.1.2,5. The analysis is necessary to assess the <br />projected effect of minewater discharge on average irrigation <br />season salinity (conductivity} on East Salt Creek waters diverted <br />for irrigation of the AVF downstream of the confluence of <br />McClane Creek and East Salt Creek. The analysis requested <br />would be a refinement of the table presented on amended page 3 of <br />Appendix N. The Appendix 3 table uses worst case assumptions <br />for minewater discharge (flow and TDS); East Salt Creek data is <br />presented for specific sampling events. Utilizing these worst case <br />assumptions in the analysis may result in a conclusion of material <br />damage. Use of actual data from DMRs for mine discharge flow <br />and TDS/EC combined with average irrigation season streamflow <br />and salinity levels will provide a more realistic and useful analysis. <br />Several modifications are requested to provide an analysis that will <br />address whether mine discharge salinity may have the potential to <br />materially damage the quality of East Salt Creek water used to irrigate <br />downstream alluvial valley floors. First, salinity data should be <br />presented as conductivity values, to al]ow for comparison with suspect <br />levels as presented in the Division's 1987 Material Damage Guideline. <br />Second, for East Salt Creek, a flow rate and salinity level that reflects <br />avera a imgation season values will need to be used in the analysis. A <br />corresponding average discharge water conductivity value (based on <br />DMR documentation) should also be used in the evaluation. If initial <br />analysis based on these factors indicates that mine discharge <br />would increase the average irrigation season conductivity on East <br />Salt Creek (and the conductivity would exceed I.0 millimhos/cm}, <br />further site specific investigations maybe warranted, as described <br />in the Guidelines. <br />20. Updated text regarding water depletion projections and USFWS Biological <br />Opinion documentation (Appendix P) was provided as requested. Item <br />Resolved. <br />21. Amended threatened and endangered species documentation was provided as <br />requested. Item Resolved. The information has been forwarded to OSM, and <br />OSM has prepared a Biological Opinion and submitted a request to USFWS to <br />initiate formal Section 7 consultation (Enclosure B). The information was <br />also forwarded to CDOW (see response in Enclosure D). The Division will <br />contact appropriate personnel at USFWS and CDOW regarding a minesite <br />visit in the near future, which maybe of some assistance in addressing any <br />remaining questions or concerns of these agencies. <br />6 <br />