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Placerville (near the headwaters to the southeast) and Naturita, Colorado. Naturita is approximately 1 1/2 miles downstream of the proposed Hamilton Mine permit area. Iorns, et al (1905) estimated that 2.8 tons of total dissolved solids (TDS) per acre are 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 have a weighted average of 316 milligrams per liter (mg/1) TDS. Specific conductivity varies between 318 and 730 millimhos (mmhos). The mean sodium adsorption ratio (SAR) is about 0.7 according to U.S.G.S data from samples taken at Naturita. Discharge records indicate that flow in this river exceeds 60 cubic feet per second (cfs) 90X of the year, while flows exceed 1,000 cfs about lOX of the year. The mean discharge of the river is 351 cfs. San Miguel River waters are suitable for domestic use except during low flow periods when sulfate levels exceed EPA domestic use standards. Naturita Creek originates near the northern edge of the San Juan Range, flowing northwest approximately 30 miles to its confluence with the San Miguel River upstream of Naturita. Naturita Creek drains approximately 203 square miles. Naturita Creek and its tributaries traverse mostly Upper Cretaceous Dakota and Lower Cretaceous Burro Canyon Sandstones which have interfingered shale, mudstone, and Dakota coal beds. There are three diversion systems within the Naturita Creek headwater area to the southeast. All return flows from these diversions enter Naturita Creek upstream from the proposed permit area. Approximately 9 square miles of the Naturita Creek drainage basin may be affected due to the proposed mining activities at the Hamilton Mine. An additional 8 square miles along Bramiers Draw may be affected. Bramiers Draw empties directly into the San Miguel River. Surface runoff from the proposed permit area flows north into Naturita Creek along Section 33 Creek. Runoff also flows west to Bramiers Draw which terminates in the San Miguel River less than one quarter mile below its confluence with Naturita Creek. Stream flow across and adjacent to the proposed permit area is ephemeral, resulting from snowmelt and storm activity only. Springs in the area which may have contributed to flow in the past have been reported dry the last several years according to data provided by Lillylands, Inc. Water in this drainage area, when present, is suitable for livestock use (from standards in National Academy of Sciences, 1974). Soils Three major and two minor soil series occur on the proposed permit area (see Section 2.04.9, Map 112 and Exhibit 7 of the Permit Application). The major soil series are the Barx fine sandy loam, 1-3X slopes, the Barx fine sandy loam, 3-6X slopes and the Progresso loam, 3-12X slopes. The two soil series that will have minor amounts disturbed are the Pinon loam, 3-50X slopes and the Paradox fine sandy loam, 1-47. slopes. -4-