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required for these sites. Prior to mining, SW2 typically flowed throughout the year, and SW1 flows were <br />sporadic In recent years flows at SWl have been minor(limited, and in the case of SW2, non-existent. Brief <br />flow was observed at site S W2 in 2003 (Table 64), while no flow was observed at S W 1 during 2003. As no flow <br />was observed at SW-1, no data Table is provided in this AHR. POR data may be found in previous AHRs. <br />In 2003, a spring and seep survey was also conducted in the northern mining district to identify potential <br />discharges to Fish Creek. The locations of these discharges and other historical discharges can be found on Map <br />37A, 2003 Spring Survey. Discharge locations were measured for temperature, pH, conductivity, and estimated <br />flaw, when adequate pooled water was available. The field data collected during the survey is contained in <br />PR03-06 Table 60.1, Northern Mining District Spring and Seep Survey. Flows were measured using a portable <br />cutthroat flume, or bucket with a stopwatch. In cases where a quantified flow could not be obtained, a best <br />estimate was made. Few springs were observed. Minor seeps were noted. <br />The northern mining district is ]oeated within the Twentymile Park Syncline. The predominant lithologic unit <br />nearest the surface and occupying most of the basin is the Lewis Shale, which can be upwards of 700 feet thick. <br />The lack of significant bedding planes, faulting, or fracture zones in this area may account for the lack of springs <br />in the central portion of this basin. The few seeps observed in the basin may be the result from surface <br />weathering of the Lewis Shale, which may allow some accumulation of water beneath overburden. This may <br />result in a short period of seepage immediately following spring mnoff. <br />. 3.6 Mine Water Discharee Sites <br />Two mine water discharge sites associated with [he TCC operations are monitored. Site 109 requires quarterly <br />monitoring for flows, field parameters, and water quality samples, and site 115 is monitored as a CDPS discharge <br />point in accordance with the requirements set forth under CDPS Permit No. CO-0042161. Monitoring <br />requirements at both sites were fulfilled during 2003. <br />When pumping mine water from the Fish Creek Borehole (mine discharge site 115) the flow becomes a <br />contributor to sulfate levels in Fish Creek. When pumping mine water from the EMD Dewatering Well (mine <br />discharge site 109) the flow becomes a contributor to sulfate levels in Foidel Creek. Fish Creek and Foidel <br />Creek, in turn, contribute to the sulfate levels in Trout Creek. Trout Creek currently has a secondary drinking <br />water standard limiting sulfate to 250 mg/1. <br />No direct discharge to Foidel Creek occurred from site 104 in 2003 (Table 65). Table 65A provides a period of <br />record statistical summary of collected data at the site. Figure 125 provides a graphical representation of POR <br />field conductivity for mine water discharged at site 109. <br />Dewatering of the Southwest Mining District through site 115, suspended in Febmary 1996, was resumed in <br />August of 1998. The 2003 Water Year data for mine water discharge site 115 is presented on Table 66. Table <br />• 66a and 666 provides the POR statistical summary. Table 66c presents water pumping records at site 115 for the <br />2003 Water Year. Figures 114 and 115 present graphical data for this site. <br />14 <br />