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presented in Appendix C. The discussion of water quality will be limited <br />to a description of total dissolved solids (TDS) concentrations. A <br />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 this <br />plot is generated by a method known as LOWESS (Locally WEighted <br />Scatterplot Smoothing). Unless otherwise noted, a smoothness factor (SF) <br />of 1.0 (on a scale of 0 to 1) was used, which results in maximum <br />"smoothing ". <br />- Alluvium. Well 68, completed in the Bond Creek alluvium (below NPDES <br />Pond 008), was drilled in 1988. Recently, it displays a decreasing TDS <br />trend, with the peak value occurring in May 2005. <br />Well 72 is located in the Fish Creek alluvium below all Seneca II and <br />PSCM discharges. This well was drilled and completed by Twentymile Coal <br />Company as part of their monitoring program. The first sample collected <br />by Seneca at this GWPOC well was in May 2009. <br />Comparison of Ground Water Quality to Water Use Standards. SCC has <br />compiled a list of ground water standards for agricultural uses (Table <br />5). This list is composed of Colorado Department of Public Health and <br />Environment ground water standards (CDPHE, Reg. 41, May 2008). <br />Table 6 provides a comparison of ground water quality data this year to <br />agricultural standards. This Paradox database generated table does not <br />include the units of concentration (mg /l or ug /l) for each parameter. <br />The units used for each parameter are the same as those listed on the <br />standards table (Table 5) and are also the same as those used in the <br />water quality reports. The frequency column on Table 6 indicates, in <br />this order: uncensored, that is, the number of exceedances above the <br />Method Detection Limit (MDL) / the number of exceedances between the MDL <br />4 <br />