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increasing trend. The Seneca II -W PHC predicts an average irrigation season TDS <br />value of 2451 mg /1 at this site, while a value of 1860 mg /1 was observed in 2009. <br />The ephemeral drainage tributary to Dry Creek, which drains the "D" Pit <br />reclamation area in the northern portion of the original permit area, is monitored at <br />the Pond 005 outfall NPDES site. <br />Sage Creek <br />SCC monitors one NPDES site on Sage Creek, at the Pond 009 outfall. Flow and <br />field parameters are recorded monthly upstream and monthly samples are taken for <br />the parameters listed in Appendix 15 -1. In addition, SCC monitors an NPDES site <br />at the Pond 015 outfall, located on a south tributary of Sage Creek. <br />Seneca Coal Company has installed a sediment control system to divert, convey <br />and /or treat surface water runoff in and around the mine site. The sediment control <br />system includes six sedimentation ponds (Ponds 005, 006, 009, 015, 016, and 017). <br />A more complete discussion of this system is contained in Section III.C. of this <br />document. <br />Flow and water quality measurements are taken at all sedimentation ponds, in <br />accordance with the Colorado Discharge Permit System permit issued by the <br />Colorado Department of Public Health and Environment, Water Quality Control <br />Division. <br />The permit application contains provisions for ongoing surface water monitoring. <br />The water monitoring plan is detailed in Tab 15. <br />Seneca Coal Company has included a plan for an alternative water supply in the <br />event that local water rights are adversely impacted by mining. The plan is included <br />in Tab 16 of the permit. <br />F. Probable Hydrologic Consequences <br />A determination of the probable hydrologic consequences of the mining and <br />reclamation activities at the Seneca II -W Mine site has been made by the applicant <br />and is found in Tab 17 of the permit application. Pages 1 -85 of Tab 17 narrative <br />focus on hydrologic impacts of mining within the original permit area. Pages 86- <br />143 address impacts of mining within the south extension area. This section <br />includes an evaluation of quantity and quality effects on ground and surface water <br />systems and mitigative measures to be taken both during and after mining. <br />The Probable Hydrologic Consequences section of this document is divided into two <br />subsections (Ground Water Effects and Surface Water Effects). The ground water <br />effects section has been updated by inclusion of a II -W South Extension addendum. <br />Seneca II -W Findings Document 34 C- 1982 -057 <br />Permit Revision No. 6 January 6, 2012 <br />