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1.0 -INTRODUCTION - _ __ __r ~~m ,_-- ,- -_ _.. _~-z_ Basin Resources, Inc. (Basin) owns and operates the Golden Eagle underground coal mine in southern Colorado. Mining of the Golden Eagle Mine ceased on December 31, 1995. The Golden Eagle Mine facilities azea was reclaimed throughout 1996 and early 1997 with the sediment control system being reclaimed in November 1998. This report presents the hydrologic monitoring activities conducted at the Golden Eagle mine during 2002 and analysis of trends over anineteen-year monitoring period. The remainder of this section describes the mine site area and the current hydrologic monitoring program. Section 2.0 describes the monitoring methods used for the program while Section 3.0 provides the monitoring results and hydrologic consequences. Also included in this report is a discussion of mitigative measures taken to minimize disturbance to area hydrologic functions (Section 4.0) and plans for future hydrology monitoring activities (Section 5.0). Data and information related to this assessment are presented in the Appendices of this report. 1.1 SITE DESCRIPTION The Golden Eagle portal area is located approximately three and one- half miles west of Weston (T33S, R67W) in Las Animas County, Colorado. The mine is situated in mountainous terrain with numerous canyons contributing runoff to the drainages of ephemeral, intermittent, and perennial streams of the area (Permit Document, Map 7A and 7B, Regional Hydrology). The mine is also located on the Middle Fork of the Purgatoire River, about 3.5 miles downstream of the confluence of the North Fork. The confluence of the South Fork ofthe Purgatoire River is at Weston, approximately four miles downstream from the mine. Most surface facilities were adjacent to, and underground mining occurred under and to the north and south of, the Purgatoire River in an area known as the Pickettvire Valley. These surface facilities were the most visual indicators of a coal mining activity in the area. The Purgatoire River is the primary stream drainage in the azea. The headwaters of the Purgatoire are located on the eastern slope of the Sangre de Cristo Mou~ttain Range west of the mine area. The general direction of stream flow is easterly to the confluence with the Arkansas River, also in Las Animas County. Principal tributaries of the Purgatoire River in the immediate vicinity of the mine are Apache Canyon, Ciruela Canyon, and Santistevan Canyon. Apache Canyon drains a watershed ofapproximatety 7,264 acres. Cover in the canyon is primarilywoodland with a herbaceous valley bottom. Primary land use is grazing and wildlife habitat. Surface mine features within the Apache Canyon watershed (on the Left Fork) include two ventilation shafts for the now inactive New Elk Mine. Portions of Apache Canyon have been (room and pillar) undermined. Apache Canyon discharges into the Purgatoire River above the Golden Eagle Mine surface facilities. Apache Canyon was determined not to meet alluvial valley floor criteria. Ciruela Canyon has a drainage area of 1745 acres with primary land uses of grazing and wildlife habitat. Cover in the canyon is primarily woodland with a herbaceous valley bottom. There are two on-stream impoundments in the upper headwaters which retain surface flow for livestock watering. Two mine ventilation shafts, a development waste pile, and a mine water discharge treatment pond (Pond 002) for the Golden Eagle Mine were located in Ciruela Canyon. Pond 002 was reclaimed in September 1996, and other Golden Eagle facilities were reclaimed over the course o£ 1996. The lower reach of the canyon is undermined by development mining. Ciruela Canyon was determined not to meet alluvial valley floor criteria. The Santistevan Canyon drains a watershed of approximately 7566 acres. A majority ofthe upper drainage has been subdivided into ranchettes. There are currently several houses and a lodge with a swimming pool. These structures utilize water from wells and in addition, the lodge is served by Trinidad City water. Waste disposal 29Z-2002 AH Report (Mar.03.03}_rev2