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EFCI Southfield Mine -Year 2007 Annual Hydrology Report April 21, 2008 <br />Oak Creek flow measurements made after 1998 aze presented for all stream monitoring locations <br />on Table 9. Earlier steam flow data are documented in previous Annual Hydrology Reports on file <br />at the Division. Total precipitation during the year was below normal, with most of the measurable <br />precipitation falling during the late winter through early spring. Runoff from melting snow and <br />later rain events caused Oak Creek to flow during most of the year. <br />Water samples from Oak Creek were submitted to the lab with a parameter list inadvertently <br />copied from an EFCI's hydrology monitoring files that omits numerous parameters or specifies <br />dissolved rather than total species concentrations. The resulting lab analysis therefor provided <br />limited data for the 2007 monitoring results as shown on Tables 12 and 13 for Oak Creek. In <br />addition, the required monitoring frequency was misinterpreted as sampling the downstream <br />location twice per yeaz and the upstream location one time (rather than twice) annually. EFCI has <br />subsequently reviewed the approved permit requirements for surface water sampling frequency <br />and laboratory testing and will conduct future monitoring in accordance with these specifications. <br />Review of historic stream flow data for Oak Creek indicates little variance between up stream and <br />down stream monitoring stations but significant reductions in flows for the past 5 years reflect <br />continuing drought conditions. <br />Historic field and laboratory water quality data for surface water monitoring stations on Oak, <br />Creek are summarized in Tables 12 and 13, Water Quality Data, Oak Creek. Raw field and <br />laboratory data for 2007 aze provided in Appendix B. <br />Historically the two sedimentation ponds have not held water or dischazged to the stream system. <br />Similar to previous years, both ponds remained dry so there was no pond dischazge during 2007. <br />2007 AHR.doc WP Page 20 <br />