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POWDERHORN COAL COMPANY 2001 ANNUAL HYDROLOGIC REPORT OCTOBER 1, 2000 THROUGH SEPTEMBER 30, 2001 Introduction During the 2001 Water Year, the Year, the mines were idle. Mining ceased at the Roadside Portals on December 2, 1999. The North Mine was sealed on February 10, 2000. The Roadside South Mine was sealed on April 12, 2000. The South Fan was sealed May 22, 2000. The 2 West Portals were sealed on April 24, 2000. Production at the Roadside North utilized room and pillar mining with a continuous miner and shuttle cars. The general format of this report is the same as in previous years. Surface Water Water flow and quality on the Colorado River is monitored by the U.S. Geologic Survey (USGS) at various locations. The closest location is Station No. 09095500 which is located upstream approximately 7 miles north east of the mine site. Water quality and flow from • this site are used as a general representation of the Colorado River up gradient of the mining operation. There is a diversion to the Government Highline Canal, the addition of Plateau Creek and the addition of other minor drainages between the monitoring site and the mine site. Data Pages SQ-26 and 27 include information supplied by USGS on this site in 2001. The total flow at this site for the Year was 1,939,000 acre-feet which is 67% of the normal average flow for the period 1934 -2001 (2,882,200). The estimated TDS load for the Year was 1.2 million tons. This estimate is made using the values for dissolved solids reported on page SQ-27 times the monthly flow in acre feet. The low flow for the Year was recorded as 1,340 CFS on February 2, 2001 and again on March 17,2001. The river was carrying approximately 1.0 tons of TDS per acre-foot on March 17~". This flow and TDS load equates to approximately 2,658 tons of Total Dissolved Solids, TDS, being carried by the river past the mine that day. Worst case mine discharges occurring on March 14, 2001 (the closest monthly analysis), were: 001 - 85 GPM @ 790 mg/I TDS; 002 -110 GPM @ 100 mg/I TDS; resulting in approximately 1.39 tons of TDS being discharged. Comparing the calculated TDS load in the River at low flow and the mine discharge near the same date, the maximum increase in the River's TDS as a result of mine discharge would have been 0.05%. • This Year's mean daily flow values for the Cottonwood and Rapid Creek flumes are included on data pages SG-31, SH-25, and SI-25. Flow at SWGS-001 is presented