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Surface Water Quality <br />• Applicable standards for the Lorencito Canyon Mine are set forth by the Colorado <br />Department of Public Health and Environment, Water Quality Control Commission <br />document Classifications and Numeric Standards for Arkansas River Basin (3.2.0), <br />effective August 30, 1995. Receiving stream standards from Region 7, Lower Arkansas <br />River Basin- Stream Segment 5a were utilized. These standards refer to the Mainstream <br />of the Purgatoire River and the Middle Fork of the Purgatoire from the USGS gage at <br />Stonewall to Interstate 25. Standards included physical, biological, inorganic, and metals. <br />Surface Water Stations <br />Data was collected from each of the surface water stations during the 1996 to 2006 <br />monitoring period. Each of the stations was monitored for field parameters and samples <br />were obtained from the site for laboratory analyses in accordance with Table 1-1. <br />Summary tables showing the results from all the surface water locations are included in <br />Appendix 2. Stations LC-1 and LC-2 continued to show signs of increased levels of TDS, <br />sodium and SAR likely related to coalbed methane development. <br />The principal water type in the surface waters is a calcium-sodium bicarbonate type. This <br />water is typically neutral to partially alkaline, with low hardness, and low to moderate <br />. salinity, pH ranges from 7.4 to 8.7, and hardness ranges from 107 mg/L to 435 mg/L. <br />Total dissolved solids in the samples ranged from 210 -980 mg/L (filterable residue). An <br />increase in TDS of 10 mg/L has been noted between the upstream and downstream <br />stations on the Purgatoire River, likely due to higher TDS discharges from coalbed methane <br />activities in Lorencito Canyon. <br />Spring and Seep Stations <br />During 2006, one spring was monitored semi-annually for flow and field parameters <br />(SPJC-1). Flow data and hydrographs are included in Appendix V. Spring SPJC-1 had no <br />observed flow throughout the year. <br />Conclusions <br />Coal mining operations began at Lorencito during the fourth quarter of 2001 and coal <br />extraction terminated in July 2002. The mine is currently completing final reclamation <br />activities and Phase I release has been granted for the area of active mining. Monitoring <br />to date does not indicate any impacts to local or regional water resources from mining; <br />however, changes in water quality over the past two years may be caused by increased <br />coalbed methane development in lower Lorencito Canyon and side canyon tributaries. <br />• <br />8