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ended probably reflect the gradual recession of tail waterdischarge (hence, higherconcentrations) <br />after irrigation ceases. <br />Surface water Site SW-N103 was situated in Calamity Draw about .6 miles downstream of <br />SW-N101. It was the furthest downstream monitoring site Peabody routinely monitored for water <br />quality in Calamity Draw. Monitoring for water quality at SW-N103 began in July of 1986 (see <br />Peabody Appendix 7-9) <br />The water type at Site SW-N103 for both seasons was a calcium magnesium sulfate (see Peabody <br />Appendix 7-8). This water type was very similar to waters sampled upstream in Calamity Draw at <br />Site SW-N101. During periods of irrigation, the major ions at SW-N103 were slightly lower than <br />shown at SW-N101. This suggested that contributions to flow in Calamity Draw between these <br />sites due to irrigation tail water provided a dilution effect. <br />Little variability between the seasons for pH was detected at SW-N103. During irrigation, pH <br />averages 7.84 and ranges from 6.84 up to 8.10 units. Afterthe irrigation season, pH averages 7.88 <br />and ranges between 7.50 and 8.06 units. <br />Similar to previously discussed surface water monitoring sites, the mean of TDS during the <br />non-irrigation season was more than double (3,135 mg/I) the mean for this constituent during the <br />irrigation period (1,371 mg/I). Again, the higher levels of the major ions in Calamity Draw at this <br />site after irrigation stops explains this trend. <br />At Site SW-N103, both TSS and Fe, averaged higher during the irrigation period (57.0 mg/1 and <br />1.46 mg/I, respectively) than after irrigation has ceased (39.4 mg/I, TSS and 1.05 mg/I FeT). The <br />mean value of Feo was slightly higher (.04 mg/1) during the non-irrigation period compared to the <br />average Fep (.02 mg/I) determined for the irrigation season. As seen for all previously discussed <br />sites, MnT averaged consistently higher (1.24 mg/I) after the irrigation season ended than during <br />the irrigation period (.33 mg/I). _ <br />West Lateral Irrigation Ditch -Flow and Water Quality. The West Lateral irrigation ditch is part <br />of the Colorado Co-operative Company's main ditch system that originates on the San Miguel River <br />(Revised 25 Jul 2002) 2.04.7-29 <br />