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1390 mmhos and ranged 720 to 2700 mmhos. The results of a 1979 study conducted by <br />Leonard Rice Consulting Water Engineers show that overall quality has not been <br />significantly affected by mining activities. <br />The report stated that measurements made in 1979 were within the range of variation seen in <br />] 974 and 1975, though they were in general lower than the historical data. The most probable <br />explanation of this apparent increase in water quality may be a dilution effect from the <br />relatively high runoff throughout the spring and summer of 1979. The report stated that there <br />is no evidence of contamination of the groundwater by the surface mining of Colowyo Coal <br />Company. Additional monitoring of the Goodspring Creek alluvium/colluvium and downdip <br />of the Gossard Loadout also indicates groundwater quality has not been sienificantly affected <br />by mining activities. <br />Surface Water <br />Occurrence of Surface Water <br />General Area <br />The surface water of the general area is characteristic of a high altitude environment. The <br />climate is semi-arid, characterized by low precipitation, large daily Cemperature changes, low <br />humidity, moderate winds and abundant sunshine. Precipitation averages 21.5 inches across <br />the drainages in the "general area" per year resulting in erratic and low flows in the major <br />• drainages near the mine area. Climatic data is discussed in detail in Section 2.04.8. Surface <br />flows are dominated by the occurrence of runoff events resulting from either snowfall or <br />rainfall. Snowfall derived runoff dominates the hydrologic cycle, supplemented by periodic <br />intense thunderstorms which result in flashy flow conditions. The quantity and quality of the <br />surface water also reflects the high evapotranspiration rates and the predominance of <br />sandstones, shales and coals in the basin. <br />See Section 2.04.6 for a description and discussion of the geology in the Colowyo Mine area. <br />The mine area is drained by Streeter Gulch, an ephemeral tributary to Goodspring Creek <br />which is a <br />• <br />2.04.7-27 <br />