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the list of parameters that were analyzed for at all surface and ground water monitoring sites. The <br />revised list included analyses for silver (total recoverable) and hexavalent chromium (total <br />recoverable). The list was temporarily revised in order to determine whether silver and chromium <br />were present in monitored water in sufficient and frequent enough concentrations to warrant further <br />sampling for each, based on stream standards for the San Miguel River. During 1987, Peabody <br />had its contract laboratory (ACZ Laboratories, Steamboat Springs, Colorado) perform total <br />recoverable analyses for silver and hexavalent chromium on two sample sets collected at each <br />surface water site. In addition, Peabody collected water quality samples in April and October of <br />1987 at two points on the San Miguel River; 1) upstream of the confluence with Calamity Draw (San <br />Miguel #2); and 2) downstream of the confluence with Tuttle Draw (San Miguel #1). The results of <br />each silver and chromium analyses performed at each surface water monitoring site can be found <br />in Attachment 2.04.7-11 (Peabody Appendix 7-9). The results of the additional analyses for silver <br />and chromium showed that total recoverable chromium never exceeded 10 ug/l; and that silver <br />exceeded 10 ug/I once each (20 ug/I at sites SW-N3, SW-N7 and SW-N102). Compared to <br />standards adopted for the nearest applicable reach of the San Miguel River (Segment 5), all <br />analyses for chromium (total recoverable) were well below the standard (25 ug/1). Unfortunately, <br />the detection limit used by the laboratory for silver (total recoverable) was 10 ug/I, significantly <br />higher than the standard (.1 ug/1). <br />With respect to Colorado Department of Health (CDOH) receiving stream standards (CDOH, 1983, <br />revised 1986), Tuttle and Calamity Draws lie within the Stream Segment 12 of Region 10 of the San <br />Miguel River. Because the listed parameters (physical and biological, only) are not applicable to <br />both Tuttle and Calamity Draws, the nearest segment (downstream) in which applicable standards <br />have been promulgated (Segment 5) are used to compare surface water quality of Calamity <br />(SW-N103) and Tuttle Draws (SW-N3, NPDES 001 and NPDES 006). <br />Exceedences were observed at three sites: 1) iron at San Miguel #1 (downstream of Turtle Draw); <br />2) zinc and manganese at SW-N103; and 3) nickel at NPDES 006. <br />Based on the rigorous comparisons made, it is evident that water delivered by the West Lateral <br />Irrigation Ditch is of sufficient quality for drinking water, agricultural use and livestock drinking water. <br />This water originates from the San Miguel River upstream of Naturita, and is currently the primary <br />2.04.7-47