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This assessment is based primarily upon data and analysis contained in the New Elk and Golden Eagle Mines permit applications, and upon the observations of Division personnel during inspections of the mine site. Some additional analysis was performed by the Division to complete the finding. This discussion is divided into four major subsections. Description of the Existing Environment, the Probable Hydrologic Consequences of Mining, the Cumulative Hydrologic Impacts of Mining, and Continued Monitoring Requirements. Surface and ground water are discussed separately in each subsection. DESCRIPTION OF THE EXISTING ENVIRONt4ENT The study area is situated in the Park Plateau, a subdivision of the Great Plains physiographic province, which consists of the dissected highlands that separate the High Plains to the east from the Rocky Mountains to the west. The Purgatoire River flows through the study area and is one of the major streams that drains the region. It farms in the Sangre de Cristo Range south of the Spanish Peaks and has three major headwater tributaries; the North Fork, Middle Fork and South Fork which converge near the study area. The study area ranges in elevation from 7,000 to 9,000 feet. Cottonwood is common on the floodplain of the Purgatoire River, whereas pinyon, juniper, scrub oak and mountain mahogany are common to the upland slopes. A. Geology The principal structural feature of the region is the Raton Basin, a broad, asymmetric synclinal basin with an axis trending north-south. The western limb is gently dipping in the study area. Steeper eastern dips are found west of the mine, outside the study area. The Raton Basin was formed during the latter phases of the Laramide Revolution when the Sangre de Cristo Range was thrust eastward. The applicant has submitted geologic maps (Map 5) and geologic cross-sections (Map 7) with the renewal application. The Golden Eagle and New Elk Mines are located on the western limb of the Raton Basin. The dip of the strata is 20 to the northeast in the general area of the mines. The coal seam at the western limit of the New Elk Mine has a dip which increases to 14 to 16 degrees. Several steep, normal faults, trending east-northeast have been mapped between Weston and Starkville (Wood. et al., 1957). Numerous faults have been mapped in the New Elk tdine workings. These faults are all high angle faults (almost vertical) and have low displacements. The maximum measured displacement of faults in the New Elk tdine workings is between 15 and 17 feet. Most faults pinch out within a very short distance. There are two major faults in the area which are extensive. They strike N80oE. One significant fracture zone has been encountered in the Golden Eagle Cline in the area of the Second Right entries. Displacement of the apparent fault associated with this zone may be approximately 30 feet. (See pages 2.04-7 thru 21 of renewal application) -11-