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provided in Report 82-874, plus additional data. In addition, most of the ground water level and <br />• quality data collected by the USGS has been incorporated into PWCC's database and is provided in <br />this PAP in Tab 7, Hydrologic Description. Table 15-2, Summary of Surface Water Monitoring Sites, <br />Yoast Mine, provides a summary of all surface water and spring monitoring sites at Yoast. Table 15- <br />3, Summary of Ground Water Monitoring Sites, Yoast Mine, provides a summary of all ground water <br />monitoring sites at Yoast. Locations for all monitoring sites may be found on Exhibit 7-1, Hydrological <br />Monitoring Sites - Yoast Mine ITab 1 5.7, Hydrologic Description). <br />The 1980 to 1983 USGS study involved the drilling and monitoring of 13 alluvial wells on Sage Creek <br />Isee Table 15-3, Summary of Ground Water Monitoring Sites, Yoast Mine, USGS numbers Al to A131 <br />and 27 bedrock wells Isee Table 15-3, Summary of Ground Water Monitoring Sites, Yoast Mine, USGS <br />numbers 1 to 271 In addition, one stream site (with flume) on Sage Creek, YSSF1 Isee Table 15-2, <br />Summary of Surface Water Monitoring Sites, Yoast Mine) was monitored. Precipitation data was also <br />collected by the USGS at Yoast from July 1980 to June 1983 (see USGS Open-File Report 90-708, <br />Table 15-9, Surface Water Monitoring Frequencies, Yoast Minel. <br />USGS monitoring frequencies and parameter lists are given in USGS Open-File Report 90-708. Table <br />and figure numbers referenced below Ithis paragraph only) are for that report. Water level <br />measurements for bedrock and alluvial wells were normally performed monthly and are presented in <br />Table 2 and Table 3, respectively. That same data is presented in hydrograph form in Figures 4 and 5. <br />• Water quality sampling from bedrock and alluvial wells were performed two to four times a year and <br />are presented in Tables 6 and 7, respectively. Water quality sampling of Sage Creek were normally <br />performed two to four times a month (during spring snowmelt runoff) and monthly (remainder of year) <br />and are presented in Table 8. A continuous flow record for Sage Creek (April 1981 to September <br />1983) is presented in Table 9 and presented in hydrograph form in Figure 6. <br />PWCC reinstituted hydrologic monitoring at Yoast in 1990. Since most of the original USGS bedrock <br />wells were to be eventually mined out, PWCC drilled eleven new bedrock wells Isee Table 15-3, Wells <br />YOV28 to YWCU311 that exist in areas downgradient of the proposed mining areas. Additional alluvial <br />wells were also drilled on Sage Creek (WSAL12, also used for Seneca II-W monitoring), Grassy Creek <br />IYGALI5), Grassy Creek tnbutar~es IYGAL76-181, and Annand Draw IYAALI4). <br />PWCC generally monitored ground water levels monthly, except during the winter months Isee <br />Appendix 7-2 for ground water level data). Ground water sampling for all bedrock and some alluvial <br />wells were performed semiannually in 1991 and 1993, and triannually in 1992. In addition, select <br />alluvial wells were sampled quarterly in 1992 and 1993. All wells drilled by PWCC Isee preceding <br />paragraph) were also sampled once in 1990 Isee Appendix 7-4 <br />• <br />3 <br />