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The New Horizon Mine 1 produced coal from both the upper and lower Dakota coal seams. The upper Dakota coal seam ranges in thickness from 1.6 feet to 3.3 feet and is separated from the lower Dakota seam by 7 to 11 feet of interbedded sandstone and shale. The lower Dakota seam varies in thickness from 5.9 feet to 7.9 feet. The base of the lower Dakota coal is 83 feet above the top of the Burro Canyon Formation. The coal dips 1° to 2° southwest and strikes N 25"W to N 45° W. The New Horizon Mine 2 primazily produces coal from the Lower Dakota coal seam and will utilize the Upper Dakota coal seam when the seam is thick enough and of sufficient quality. The lower Dakota coal seam at New Horizon Mine 2 ranges in thickness from 4.2 feet to 6.9 feet and is 99 feet above the top of the Burro Canyon Formation. The. coal dips 4.5° SW along a strike of N 45° W. Surface Water The San Miguel River has its source in the San Juan Mountains. These mountains are primazily composed of Tertiary volcanic rocks. Ioms et. al. (1965a) has shown these waters to be of a calcium bicarbonate-sulfate type during high flow periods. These waters contain less bicazbonate during low flows while the calcium and sulfate concentrations increase due to less dilution from snowmelt runoff. The San Miguel River traverses the interior portions of a basin that is chiefly underlain by Dakota Sandstones, the Morrison Formation and Mancos Shales. The Morrison Formation and Mancos Shale have the greatest potential for influencing the river water chemistry. The San Miguel River drains an azea of 1,080 squaze miles. In addition, approximately 15,500 acres of irrigated land lies between Placerville and Naturita, Colorado. It is estimated that 2.8 tons of Total Dissolved Solids (TDS) per acre aze contributed to the waters annually from this area. This results in increased levels of magnesium, potassium, sulfate and chloride. Water quality samples taken from the San Miguel River at Naturita, Colorado, have a weighted average of 316 milligrams per liter (mg/1) TDS. Specific conductance varies between 318 and 730 millimhos (mmhos). The mean sodium adsorption ratio (SAR) is about 0.7 at Naturita. Water curves indicate that, 90 percent of the time, flow in this river exceeds 60 cubic feet per second (cfs), while flows exceed 1000 cfs about 10 percent of the time. The mean discharge of the river is 351 cfs. San Miguel River waters aze suitable for domestic usage except at low flow periods when sulfate levels aze high. The Colorado Cooperative Ditch Company diverts as much as 145 cfs of water from the San Miguel River approximately ten miles east of the town of Nucla. The main diversion ditch then flows westerly passing just north of the town of Nucla and then flows northwestwazd passing north of the New Horizon Mine 1. Diversion ditches distribute water to mainly agricultural users in the area. Since the completion of the irrigation system for this area in about 1910, these areas have been intensively reworked for irrigated agriculture. Additional uses include domestic, municipal and stock pond consumption. The New Horizon Mine 1 is located downslope from the main ditch in the gently sloped upland of Second Pazk. This is just north of Tuttle Draw and is totally within its watershed. The Second Pazk Lateral Irrigation Ditch is in continuous operation from mid-April through mid-October. While this water is primarily used for irrigation, important secondary uses include maintaining water levels in stock ponds and domestic cisterns. During the non-imgation season [he ditch is occasionally turned on to maintain the water levels in the stock ponds and cisterns.