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Colowyo Coal Company <br />2008 Annual Reclamation and Hydrology Report <br />GENERAL TRENDS <br />Colowyo currently samples each surface water site for a variety of quality parameters. <br />Of all the parameters that are analyzed for, several key indicator parameters are <br />identified. These are lab pH, lab conductivity, TDS, sulfate, calcium, iron, magnesium, <br />sodium and flow rate. Statistical analysis is completed and illustrates historical trends <br />for each parameter. See graphs for the trend lines in Exhibit 2A. <br />Surface Water Data - The Rz value for linear regression is indicated below. <br />Site Id Lab <br />pH Lab <br />Conductivity TDS Sulfate Calcium Iron Magnesium Sodium Flow rate <br />(cfs) <br />NUGSC 0.0353 0.0051 0.04 0.0201 0.0151 0.0052 0.0065 0.1102 0.0139 <br />LGSC 0.0545 0.0717 0.01185 0.0089 0.00005 0.0145 0.000006 0.09767 0.0381 <br />UWFGSC 0.0167 0.1577 0.211 0.2782 0.1986 0.213 0.2409 0.2034 0.1312 <br />LTC 0.0191 0.0972 0.0489 0.0006 0.0147 0.0001 0.0011 0.0436 0.1028 <br />Summary of the indicator parameters for each surface water site is provided in the <br />following tables. <br />0 NUGSC: <br />Parameter Mean Sdted Range Max Min. Max at Min at Trend <br />Lab pH 8.12 777.97 1.1 8.6 7.5 04/27/98 10/24/02 Increasing <br />Lab Cond. 1510.98 315.23 2842 3600 758 03/06/98 05/27/93 Increasing <br />TDS 1149.31 512.87 1250 1610 360 08/06/01 05/08/02 Increasing <br />Sulfate 518.05 224.71 760 930 170 07/08/02 05/20/97 Increasing <br />Calcium 126.89 64.35 165.6 169 3.4 08/02/02 06/01/93 Increasing <br />Iron 0.78 64.80 8.53 8.54 0.01 05/17/99 02/11/02 Decreasing <br />Magnesium 123.57 65.02 226.9 228 1.1 08/02/02 04/27/98 Increasing <br />Sodium 47.90 26.83 121.1 138 16.9 11/10/08 04/27/98 Increasing <br />Flow rate 3.03 3.65 19.8 20 0.2 04/27/98 03/18/96 Increasing <br />• <br />Page 2-3