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Sage Creek basin. Due to the low aquifer transmissivities, seasonal • <br />water level fluctuations are much less pronounced than the alluvium and <br />overburden, and are often masked by water sampling effects. Well YW28 <br />(downgradient of the 1996/99 mine pit in Annand Draw) had experienced <br />decreasing water levels from October 1996 to August 2003. However, water <br />levels since October 2003 show an increase. In the Sage Creek basin, <br />water levels at Wells YW29 were decreasing, but have been increasing <br />since May 2003. Water levels at Wells 28 and 29 fall within their <br />historic ranges. Water levels at Wells YW7 and 30 are the lowest on . <br />record. <br />- Wadge Underburden. Four wells; YWU16, 28, 29, and 30; monitor the <br />Wadge underburden. Well YWU28 exists in the Annand Draw basin, all <br />others exist in the Sage Creek basin. Most of these wells do not exhibit <br />any significant seasonal variation, although some variation from year- <br />to-year is evident. Wells YWU16 and 28 exhibited water levels this year <br />within their historic ranges. Well YW[J28 (downgradient of the 1996/99 <br />mine pit in Annand Draw) has experienced a significant increase (68 . <br />feet) in October 2002, followed by a significant drop (67 feet) in <br />October 2003. In the Sage Creek basin, Wells YWU29 and 30 have <br />experienced decreases in water levels since May 1999. <br />- Wolf Creek Coal and Underburden. Wells YWC31 and YWCU31 were abandoned <br />on October 26, 2001. They were about to be buried in spoils. Wells YWC33 <br />and YWCU33 were completed in August 2002 to replace those wells. More <br />data will be needed before trends can be discussed. <br />Ground Water Quality. Table 4 shows. the ground water parameter list <br />used for all well water samples. Appendix C provides all ground water <br />quality data collected during the past two years, along with sampling <br />remarks. This is followed by a plot of TDS versus time for the entire <br />period of record. The regression line on this plot is generated by a <br />method known as LOWESS (Locally Weighted Scatter plot Smoothing). Unless <br />otherwise noted, smoothness factor (SF) of 1 (on a scale of 0 to 1) was <br />used, which gives maximum smoothing. This plot is followed by a table • <br />listing historic TDS values and percent milliequivalents for major ions. <br />4 <br />