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Lorencito Canyon Mine Annual HvdrafaRic Monitoring ReOOrt - 2001 pH/temperature meter and an Orion conductivity/temperature meter immediately at each monitoring station in accordance with 40CFR 136. Each of the sampled parameters was determined by obtaining a sample of the water with a decontaminated beaker, and placing the probes in this sample for measurement. Samples were obtained from flowing water where possible. Decontamination of all equipment was performed by first rinsing the equipment with tap water, then washing with aphosphate-free detergent, then rinsing the equipment with deionized water. Samples were obtained using the laboratory provided sampling containers, where possible. Each container was lowered into the water and filled gently, without rinsing out the preservative. For samples requiring field filtration, filtration was accomplished by use of a barrel filter with a 0.45 micron filter. Statistical Data Reduction Methodology The analytical results and field parameters were plotted to determine water types. Mean, median, and standard deviation values were generated to determine the accuracy and precision of the data. Major cations and anions were plotted on trilinear (Piper, 1944) and Stiff diagrams for comparative analyses of water types. SECTION 3 -RESULTS AND DISCUSSION The Lorencito Canyon Mine is located on tributaries south of the Purgatoire River, 2.7 miles east of Weston, Colorado. The headwaters of the Purgatoire are located eighteen miles west of the permit area, and the river is draining 403.7 square miles of watershed at its confluence with Lorencito Canyon. The Purgatoire is a tributary of the Arkansas River. Precipitation in the 2001 calendar year was drier than average throughout the year. Groundwater Quantity Water levels in al] of the alluvia] wells varied seasonally showing increases in [he spring to early summer. Generally, these water levels were consistent with 1997 through 2000 measurements. Increases noted in March and May can be attributed to spring moisture and runoff events causing flows in the stream drainage (see surface water discussion below). Also, recent coalbed methane development and associated dewatering to surface streams has increased water levels in alluvial wells in those drainages where discharge occurs. Monitoring results of water levels in these wells are contained in Appendix 1 and hydrographs of well data are also contained in Appendix 1. Groundwater Quality Data was collected from each of the alluvial wells (MWJC-1, MWLC-1, MWLC-2, and AHR-00.075\AOri136, 2002