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• 1390 mmhos and ranged 720 to 2700 mmhos. The results of a 1979 <br />study conducted by Leonard Rice Consulting Water Engineers show <br />that overall quality has not been significantly affected by mining <br />activities, <br />The report stated that measurements made in 1979 were within the <br />range of variation seen in 1974 and 1975, though they were in <br />general lower than the historical data. The most probable <br />explanation of this apparent increase in water quality may be a <br />dilution effect from the relatively high runoff throughout the <br />spring and summer of 1979. The report stated that there is no <br />evidence of contamination of the groundwater by the surface mining <br />of Colowyo Coal Company. Additional monitoring of the Goodspring <br />Creek alluvium/colluvium and downdip of the Gossard Loadout also <br />indicates groundwater quality has not been significantly 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 <br />altitude environment. The climate is semi-arid, characterized by <br />low precipitation, large daily temperature changes, low humidity, <br />moderate winds and abundant sunshine. Precipitation averages 21.5 <br />inches across the drainages in the "general area" per year <br />resulting in erratic and low flows in the major drainages near the <br />mine area. Climatic data is discussed in detail in Section 2.04.8. <br />Surface flows are dominated by the occurrence of runoff events <br />resulting from either snowfall or rainfall. Snowfall derived <br />runoff dominates the hydrologic cycle, supplemented by periodic <br />intense thunderstorms which result in flashy flow conditions. The <br />quantity and quality of the surface water also reflects the high <br />evapotranspiration rates and the predominance of sandstones, shales <br />and coals in the basin. <br />See Section 2.04.6 for a description and discussion of the geology <br />in the Colowyo Mine area. The mine area is drained by Streeter <br />Gulch, an ephemeral tributary to Goodspring Creek which is a <br />• <br />2.04.7-27 <br />