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elevation during 1995. In the fall of 1995, well 95M001 was established in part to address the apparent <br />discrepancy in water levels between wells 006-8348C and FCM#2. Water levels from well 95M001 confirm <br />that levels recorded from well FCM #2 were accurate (Figure 20). Mining in the northern mining district began in <br />1995, which is down dip of this well. Water levels in well 95M001 declined since 1994, appeared to stabilize <br />since 2002, and again declined in 2007 through 2008 (Figure 20). The declines may have been influenced by the <br />underground mining operation Since 2009 levels appear stable with a small drop in 2017 & 2018. <br />Significant inflows from the Trout Creek Sandstone into the mine workings have not been encountered to date to <br />account for the apparent lowering of the potentiometric surface in the Trout Creek formation, as indicated by the <br />water level data previously recorded for well 006-83-48C. Some dewatering of the aquifer does occur from the <br />pumping of well 001-83-106 to supply the mine with domestic water. <br />The southernmost Trout Creek well, 001-83-107 (Figure 19), water levels continued to decline from the early <br />1990s through 2012, and have appear stable since, with a small rise in 2015 and 2016. Located down dip of the <br />TC facility water well 001-83-106 (Figure 18), had appeared stable since 2000. Declines in water level at that <br />well in the late 1980's into the 1990s reflect effects from longwall mining that began in the western mining <br />district in 1990, in addition to water well use. <br />Well FBR-2-E (Figure 22), located along the eastern permit boundary exhibited consistent water levels until early <br />1999, then dropped about 50 feet and immediately stabilized with consistent water levels at the lower depth to <br />date. The specific reason for this drop was not apparent, although many historical boreholes and some faulting <br />exists in this vicinity. Unfortunately, to due contractor error, well FBR-2-E was not monitored as indicated by <br />the schedule for 2018 and therefore no data for 2018 is available. Water levels in 2017 were similar to the <br />previous water years. TDS values for FBR-2-E (Figure 23) dropped in 2001, rebounded back to historical values, <br />and began dropping again in 2003 through 2011. 2017 exhibited an historic low TDS of 224 mg/l. The exact <br />reason for this decline is unknown, and does not appear to correspond with stable water levels. The reason for <br />these jumps is unknown, but TC will continue to monitor and assess it. <br />Well 97013TC (Figure 24) water levels remained consistent from 2004 through 2010. A drop in water level <br />occurred in mid 2010, which is the result of being mined through. The water level continued to drop slightly <br />during 2018. TDS values for well 97013TC (Figure 25) were within historic values from 1997 through 2012, <br />with drops in 2013 and 2014. This also appears to be related to the well having been mined through. In 2015 <br />TDS concentrations rose. <br />Fish Creek Sandstone: Two Fish Creek Sandstone wells (91 M001 and 91 M004) require monitoring on a <br />semiannual basis for water level only. An additional well (Ashley) requires semi-annual monitoring for water <br />levels and field parameters, and annual water quality sampling. Tables 15 through 17 provide summaries of the <br />2006 Water Year data collected at each site. Tables 15a through l7a provide historical statistical summaries of <br />collected data at each site. Figure 26 provides graphical representation of the period of record water levels <br />measured at sites 91 M001 and 91 M004. 91 M004 was dry 2012 through 2015 and in 2017. <br />7 <br />