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increase in SAR. These major ion changes are more apparent during the low-flow <br />period. The increase in TDS could be caused to some extent by evapotransporative <br />effects, but this would not account for the major ion changes. These changes are more <br />likely attributable to dischazges of waters having higher sodium and sulfate concentrations <br />than the Fish Creek water, or the intrusion of different geologic strata into the stream <br />channel between sites. Sources of such discharges include the Fish Creek Borehole, and <br />disturbed azea runoff and seeps associated with the Fish Creek Tipple. There is no <br />appazent increase in iron concentrations in Fish Creek that is associated with the Fish <br />Creek Borehole or the Tipple. <br />Since 1987, with the exception of a short period during 1990, the salt content of Trout <br />Creek below Middle Creek has been consistently higher than above Middle Creek. There <br />is typically approximately 100 to 200 umhos/cm increase in field conductivity over this <br />reach. The downstream increase was apparent during the 1992 water yeaz. The Trout <br />Creek salt content increase during the spring runoff is probably due to the effects of <br />Middle Creek flows that have a higher conductivity than Trout Creek flows, primarily <br />as a result of Foidel Creek flows into Middle Creek just upgradient of the Trout Creek <br />confluence. Foidel Creek salt loads during the spring runoff aze primarily due to the <br />impact of surface mine discharges. However, the Trout Creek salt content increase has <br />not caused any material damage, nor is there any increase in trace metal levels. <br /> <br />(~ -9- 6/10/94 1:23 pm <br />