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least partly due to the effects of surface mining. The discharges related to surface mining are <br />much greater than the underground mining dischazges during the spring runoff and aze still <br />greater during the irrigation season. Therefore, the increase in the spring runoff dissolved solids <br />levels is probably due primarily to the effects of the surface mine. The increase in the salt <br />content of the water during the irrigation season is at least partly due to the effects of the <br />underground mining. <br />Other than increased levels of sodium, sulphate, and SAR in the stream no other significant <br />water quality impacts at least partly due to underground mining have been detected. The <br />increase in SAR levels during irrigation season is not sufficient to cause material damage. <br />The dissolved solids levels in the upstream station on Fish Creek Station 16 aze lower than those <br />in the two downstream stations (1002 and 1003). This is probably due to evapotransporative <br />effects and impacts from naturally saline bedrock discharge to Fish Creek as it meanders through <br />Twentymile Park. There was no indication of any impact on Fish Creek water quality from the <br />Borehole or the Tipple. <br />In 1988 and 1989 the salt content of Trout Creek below Middle Creek was higher than it was <br />above Middle Creek. This is probably due to the effects of Middle Creek flows. There is an <br />approximately 100 to 200 umhos/cm increase in field conductivity over this reach. It is likely <br />due to the impact of the underground and surface mine discharges. However, this increase has <br />not caused any material damage, nor is there any increase in trace metal levels. The increase <br />in 1990 was less apparent than in the previous two years. <br />-8- <br />