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Streams - Water Quality. This section presents discussions of water quality data collected at <br />surface water monitoring sites established at the New Horizon 2 mining area. All historic data (prior <br />to January, 1988) for each site were compiled and are presented as water quality reports in <br />Attachment 2.04.7-11 (Peabody Appendix 7-9) and Attachment 2.04.7-9 (Peabody Appendix 7-7). <br />Specific Tuttle Draw water monitoring data is included by reference to Tab 7 (Section 7) in Volume <br />B, pages 7-123 to 7-132, of New Horizon 1 Reclamation Plan. <br />Surface water monitoring Site SW-N101 was located in Calamity Draw upstream of the eastern <br />boundary of the New Horizon 2 mining area (see Map 2.04.7-1A). Monitoring of water quality at <br />this site was initiated in July of 1986 for purposes of collecting baseline information for the New <br />Horizon 2 mining area. See Attachment 2.04.7-11 (Peabody Appendix 7-9). <br />For both seasons, the water type at Site SW-N101 was a calcium magnesium sulfate. The mean <br />milliequivalent values for each major ion increased during periods of non-irrigation. <br />Average pH measured at SW-N101 was less during periods of no irrigation (7.64) compared to the <br />mean pH representative of the irrigation season (7.82). However, the pH range was larger (7.23 <br />- 8.05) during the non-irrigation months than when irrigation was occurring (7.44 - 7.98). <br />Average TDS dramatically increased at SW-N101 when irrigation shut down, being almost three <br />times the mean (2,942 mg/1) determined at this site when irrigation occurred (1,026 mg/1). <br />Increases in the major ions occurred after irrigation stops greatly influenced increase in TDS, while <br />the relative proportions (percent mill iequivalents) of each ion remained fairly constant. <br />Based on the period of record, TSS, FeT and Fep all averaged greater (71.3 mg/I, 1.79 mg/I and .48 <br />mg/I, respectively) during the irrigation season than the non-irrigation period (28.3 mg/I, 1.12 mg/I, <br />and .15 mg/I, respectively). The opposite was true for MnT, averaging 1.43 mg/l when irrigation <br />ceased (mid-October through mid-April) compared to a mean of .40 mg/1 during irrigation. <br />Site SW-N102 was located on the lower end of a small return ditch that flows into Calamity Draw <br />approximately one quarter mile downstream of Site SW-N101. When flowing, water quality samples <br />were collected at this site since July of 1986 (Attachment 2.04.7-11 (Peabody Appendix 7_9)) <br />2.04.7-38 <br />i