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2001 HydroloR+c Report <br />in September 1996, and other Golden Eagle facilities were reclaimed over the course of 1996. The <br />lower reach of the canyon is undermined by development mining. Ciruela Canyon was determined <br />not to meet alluvial valley floor criteria. <br />The Santistevan Canyon drains a watershed of approximately 7566 acres. A majority of the upper <br />drainage has been subdivided into ranchettes. There are currently several houses and a lodge with <br />a swimming pool. These structures utilize water from wells and in addition, the lodge is served by <br />Trinidad City water. Waste disposal is by means of septic systems and drain fields which may <br />supply additional water to the surface drainage system. Three USGS springs have been identified <br />in the canyon and appear out of fractures between sandstones and shales which outcrop on the <br />surface. Cover is comprised mostly of woodland. Grazing and wildlife are the major land uses. <br />Mining was also a land use with an exhaust shaft and a power substation located in the canyon. <br />Longwall mining panels perpendicular to the direction of flow underlie the canyon. During 1989, <br />a determination was made that the canyon does not meet alluvial valley floor criteria (see Exhibit 30 <br />of the Golden Eagle Permit Document). <br />The geologic setting is an important factor when analyzing hydrology of an area, Stratigraphy in the <br />region ranges in age from Pre-Cambrian to Quaternary, However, only portions of the Raton <br />Formation (see Figure 1.1-1) and recent alluvial deposits aze exposed in the area of the mine. Most <br />of the formation consists of very fine to medium grained sandstone interbedded with siltstone and <br />shale. Coal that was mined at the Golden Eagle is located near the middle of the Raton Formation. <br />The outcrop of the formation in the area may be characterized as stream deposits including <br />channel-point bar fades, floodplain deposits and swamp deposits. <br />Alluvial deposits along the Purgatoire Rivet are complex. The headwaters of the river are underlain <br />by volcanic rocks and sediments. As it flows to the east, the river cuts its way through many <br />different geologic formations including Pleistocene glacial-fluvial sediments, foothills belt of <br />Paleozoic-Mesozoic strata, terrestrial sediments of the Tertiary, and marine deposits of the Pierre <br />Shale. Channel shape and structure of the Purgatoire vary within each of these formations as does <br />the water quality. Alluvia] deposits in the area ofthe mines range from their current location to older <br />terraces of forty to fifty feet above the Purgatoire. Buried channels which are incised into the <br />underlying Raton Formation have also been found. Purgatoire River alluvial deposits support typical <br />hydrophytic vegetation characteristic of floodplains and contain groundwater hydrologically <br />connected to the Purgatoire River. The Picketwire Valley of the Purgatoire River alluvial deposits <br />has been designated as an alluvial valley floor and is classified as a renewable resource. <br />Soils are generally shallow and coarse-grained. They aze derived from the underlying sandstones <br />and shales. Bedrock exposures are common and scattered throughout the area. The valley bottoms <br />are characterized by alluvial and colluvial deposits which are also coazse-grained and deeper than <br />soils of the mountain slopes. <br />Nl00AHHepnn-HPT(292)/April /9, 2002 2 <br />