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greater mine area. Lands in this area are a small part of the larger Park Plateau, a portion <br />of the Great Plains physiographic province, consisting of dissected highlands that separate <br />the High Plains to the east from the Rocky Mountains to the west. <br />The major structural feature of the region of the mine area is the Raton Basin, a broad, <br />asymmetric synclinal basin with its axis trending north-south. Rock units deposited during <br />the Cretaceous period of the Mesozoic Era and during the Paleocene period of the <br />Cenozoic Era are exposed throughout the basin due to uplift and subsequent erosion. <br />Coal seams in the Vermejo Formation and the Raton Formation are exposed at various <br />locations throughout the basin. Coal mining is no newcomer to the region, as mining has <br />been conducted since the 1850's, mostly in underground mines faced-up into coal seam <br />outcrops in the valleys. Coal quality is generally very good, with low sulfur content and <br />good coking qualities in many of the seams. Due to parting and splits in the seams, much <br />of the coal mined in the region requires washing prior to loadout and shipment. <br />The Purgatoire River flows through the area and is the major stream that drains the region. <br />Its headwaters are in the Sangre de Cristo mountain range to the west and the Spanish <br />Peaks to the northwest. The North Fork of the Purgatoire drains the Spanish Peaks area, <br />the Middle Fork drains the area west of Stonewall, Colorado, and the South Fork of the <br />Purgatoire drains the areas south of Colorado Highway 12 into New Mexico to the south. <br />The Purgatoire River drains 404 square miles above its confluence with Lorencito Canyon. <br />The United States Geological Survey (USGS) has operated two stream gauging stations in <br />the vicinity; site 07124050 at Stonewall, Colorado and site 07124200 at Madrid, Colorado. <br />The Stonewall site drains 57 square miles and the Madrid site, above Trinidad Reservoir, <br />drains 505 square miles. Numerous perennial, intermittent, and ephemeral streams drain <br />to the Purgatoire between these two sites. <br />Surface water is characterized as a calcium/sodium bicarbonate water, neutral to slightly <br />alkaline, with low hardness. pH ranges from 6.15 to 8.8 and Total Dissolved Solids (TDS) <br />ranges from 50-650 mg/I. <br />Ground water occurrence in the region can best be described as limited. Consolidated <br />bedrock aquifers generally have a low hydraulic conductivity and a low storativity, rendering <br />bedrock aquifers unusable for sources of economic water. Alluvial groundwater is present <br />in the major alluvial valleys of the region and is used for domestic purposes associated with <br />ranching activities. <br />Ground water quality is variable, but can generally be described as fair quality. Alluvial <br />water is suitable for most uses where TDS levels are not elevated. Bedrock water quality is <br />fair from shallow aquifers, but degrades with depth and would not generally be suitable for <br />domestic use. <br />Lands in Las Animas County are classified and divided into zoning districts. There are two <br />zoning districts within the Lorencito Canyon permit area; the Agricultural District and the <br />Rural Residential District. Underground and strip mines are a conditional use of these <br />zoning districts and require a special use permit.