2016-08-03_REPORT - C1982056 - Laserfiche WebLink

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relatively rapid increases and declines associated with spring runoff. The longer-term trends in water levels at these sites generally parallel the fluctuations observed in annual stream flows. Field conductivity measurements in general at well 001-S-5 were noted to be slightly lower than the up gradient site, 009-S-10. There appears to be a general increasing field conductivity trend for well 001-S-5 through 2010 (Figure 32). Conductivity values dropped in 2014 and 2015, but are still within historic levels. Down gradient, field conductivities at well 008 -AV -2 ranged between 1480 and 1830 for 2015. Field conductivity measurements at wells 008 -AV -1 and 008 -AV -2 are comparable and occurred within previously established ranges for these sites. Fish Creek Alluvial Groundwater: Monitored water quality parameters exhibited values at the Fish Creek alluvial wells which were typically within previously established ranges. There are four older Fish Creek alluvial wells (006 -AY -1, 006 -AZ -3, 008 -AU -3 and 008 -AW -3). Tables 23 through 26 provide summaries of the 2015 Water Year data collected at each site. Tables 23a through 26a provide POR statistical summaries of collected data at each site. Figures 34 through 37 provide graphical representations of water levels and selected water quality parameters recorded at each site. In addition to the four wells discussed above, three additional alluvial wells, AVF-13 and AVF-14 (installed in August 2001), and AVF-15 (installed June 2002) were added per PR99-05, 4e-7. Monitoring frequencies for these wells are different than that for the four older wells above (see Table 18). Water levels at well 006 -AY -1, located on Fish Creek upstream of the Southwest Mining District and Mine 2, had exhibited a relatively steady increase in water level from approximately 1990 through 1994 (see Figure 34). From 1994 through 1997, that trend has reversed and is generally decreasing from 1994 through 2000, and appears to have subsequently stabilized. POR conductivity data has been relatively consistent the last several years (Figure 35). Well 006 -AZ -3 is situated downstream of 006 -AY -1 and below the Fish Creek Borehole. Well 006 -AZ -3 is monitored in conjunction with surface water site 307. Several water years are presented to show relative seasonal fluctuations (Figure 36). POR conductivity data has exhibited a general increase since the late 1980's, but appears to have stabilized since 2000 (Figure 37). Downstream of 006 -AZ -3 are relatively new alluvial wells, AVF-13, AVF-14, and AVF-15. Data for sites AVF- 13, AVF-14, and AVF-15 are provided in Tables 29, 30, and 31, respectively. Figures 38 through 43 provide graphical representations of water levels and selected water quality parameters recorded at each new site. Note that localized mining subsidence along Fish Creek occurred in the area of well AVF-15 during the summer of 2004. The general location area of AVF-15 has subsequently been permanent ponded. Note that per our subsidence plan, alluvial 008-AU3 replaced AVF-15 as the downstream monitoring well for subsidence evaluation in 2006. Note that Well AVF-15 was replaced in 2014, and is located in the same general vicinity. Well 008 -AU -3 and surface water site 305 monitor water levels upstream from the Fish Creek Tipple area with data presented on Figure 44. The furthest downgradient Fish Creek alluvial monitoring well is 008 -AW -3 (Figure 46) located near the Fish Creek Tipple. No unusual water level fluctuations were noted at any of these sites during 2015. Similarly, conductivity values for these two sites were within historical ranges. 01