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areas enters the creek in two discharge points in the final 3/ mile above the LGSC <br />station. Please refer to Map 10A, Hydrologic Features and Monitoring Locations in <br />Volume 14 of the Permit application for the locations of these monitoring sites. <br />The complete data records of these two stations are included in Exhibit 2A of the annual <br />Reclamation and Hydrology Report, and are reproduced herewith as Tables 4-2 and 4- <br />3, respectively, for the upstream (NUGSC) and downstream (LGSC) stations. Three key <br />parameters, namely stream flow, TSS and TDS data have been extracted from those <br />records and presented here as Table 4-1, which is a side-by-side comparison of those <br />parameters for each common sampling date. Graphical plots of those parameters are <br />presented here as Figures 4-1, 4-2 and 4-3 respectively for stream flow rate, TSS and <br />TDS. <br />It should be noted that the stream flow rates are very dependent on local climatic <br />conditions and withdrawals for irrigation use, and that the mine permit area <br />encompasses only a few percent of the entire tributary watershed. In that regard, the <br />bottom lands in Good Spring Creek between these two sampling stations are actively <br />irrigated for about half of the distance between the stations. <br />Notwithstanding the above, the comparison of total flow over the years of record for the <br />stream flow above and below the mine area presented as Figure 4-1 shows that the <br />flow is characterized by base flows on the order of 1 to 5 cfs, with peaks as high as 50 <br />cfs during large spring melt events or large Summer and Fall rainy periods or <br />thunderstorms. As would be expected, the flows in the lower site, immediately below <br />Colowyo's outfall at Streeter Pond, are generally larger than those at NUGSC, but the <br />large watershed of Elkhorn Creek reports between these two stations and probably <br />accounts for a good part of that difference. <br />It can also be observed on Figure 4-1 that the magnitude of the peak flows downstream <br />of the mine (Station LGSC) has attenuated somewhat since the mine has been in <br />operation. This is likely due to the operation of the mines' surface water management <br />system, including sedimentation ponds, and the 100% capture of precipitation falling on <br />the currently active pit. <br />With respect to water quality, the parameters TDS and TSS are viewed as the most <br />relevant to assessing the hydrologic impacts of the mine. <br />In Figure 4-2, peak TSS concentration appears to be essentially flat at the upper station <br />when evaluated with respect to time, but shows a significant reduction in peak <br />concentration since 1984 in the station immediately below the mine. This also is <br />probably a consequence of the mine's surface runoff control system of stabilized <br />diversion ditches and sedimentation ponds. In most cases the TSS concentration in the <br />uncontrolled natural watershed reporting to the upstream station NUGSC is now higher <br />than the corresponding value at the downstream station immediately below the mine. <br />TDS at the station below the mine appears slightly higher on all corresponding sampling <br />dates than its corresponding value upstream of the mine. As mentioned previously, <br />irrigation water diversions in the areas between the two stations and in the Elkhorn <br />Phase 111 Bond Release Application 14