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precipitation recharge or the lack of precipitation. Overburden and <br />coal well water levels are fluctuating in response to the precipitation <br />recharge, induced ground water flow to the mine pits, and in some cases, <br />changes in reservoir water levels. Spoil well water levels still <br />indicate that only the furthest downslope highwall portions of the spoil <br />exhibit significant amounts of saturation. <br />Ground Water Quality. Ground water samples were collected from 19 wells <br />on a biannual basis. In addition, two wells (SOV42 and SSP25) that are <br />required to be sampled did not have enough water to sample. The <br />parameter list used for all wells sampled this year is given on Table. 4. <br />Analyses have been performed by ACZ Laboratory in Steamboat Springs, <br />Colorado since May 31, 1983. ACZ Laboratory performs all analyses by <br />EPA-or equivalent methods. Samples are delivered the day of collection <br />to the lab in an iced cooler. A complete description of the ground <br />water monitoring program may be found on pages 7-336 to 7-355 of the <br />Seneca II PAP, and is summarized on pages 7-341/342. <br /> • <br />The following discussion of the analytical data collected during the <br />reporting period is arranged by strata being monitored and coincides <br />with the format (by aquifer type) in which the analytical data are <br />presented in Appendix C. The discussion of water quality will be <br />limited to a description of total dissolved solids (TDS) concentrations. <br />A separate section, Comparison of Ground Water Quality to Water Use <br />Standards, will discuss any samples that exceed water use standards. <br />Data for each well in this appendix begins with a listing of the water <br />quality data collected during the past two years, followed by remarks <br />explaining the sampling procedure. This is followed by a plot of TDS <br />versus time for the entire period of record. The regression line on <br />this plot is generated by a method known as LOWESS (LOcally WEighted <br />Scatterplot Smoothing). Unless otherwise noted, a smoothness factor <br />(SF) of 1.0 (on a scale of 0 to 1) was used, which results in maximum <br />"smoothing°. Finally, this plot is followed by a table listing historic <br />TDS values and percent milliequivalents for major ions. <br />6 <br />