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Permit C-81-071 1995 Annual Hydrology Report • The dissolved solids concentrations in the upstream station of Fish Creek (16) are generally slightly lower than those in the downstream station (1002). There is also a slight downstream trend of increasing sodium and sulfate concentrations while calcium, magnesium and bicarbonate concentrations remain fairly consistent. The proportionally higher sodium concentrations over calcium and magnesium leads to a slight downstream increase in SAR. These major ion changes are more apparent during the low-flow period. The increase in TDS could be caused to some extent by evapotransporative effects, but this would not account for the major ion changes. These changes are more likely attributable to discharges of waters having higher sodium and sulfate concentrations than the Fish Creek water. One source of such discharge is the spoil runoff and springs associated with Mine 2. However, the very low flows associated with the Mine 2 disturbed areas indicates minimal influence from this source. The primary source of such water at this time is the underground mine discharge point located near Mine 2. Since 1987, except for a short period during 1990, the salt content of Trout Creek below Middle Creek has been consistently higher than above Middle Creek. Typically, there is approximately 100 to 200 umhos/cm increase in field conductivity over this reach. The downstream increase was apparent during the spring runoff period. The Trout Creek salt content increases during the spring runoff. This is probably due to the effects of Middle Creek flows that have a higher salt content than Trout Creek primarily as a result of Foidel Creek which flows into Middle Creek just upgradient of the Trout Creek confluence. Foidel Creek salt loads during the Spring runoff are primarily due to the impact of surface mine discharges. However, the Trout Creek salt content increase has not caused material damage, nor is there any increase in trace metal • levels SPOIL SPRING MONITORING A spoil spring monitoring program was initiated in 1986 and will be conducted annually until such time as the monitoring requirement is eliminated. According to the approved plan, the annual mine-wide survey is conducted during May, and springs are measured for flow and field parameters. If a spring is discharging 35 gallons per minute or greater than it is monitored throughout the remainder of the year in accordance with the monitoring plan. Flow The field data of the 1995 spoil spring monitoring program is presented on Table 47. A plot of the historic flow data for Station 114 is presented on Figure 44. Due to pumping of Site 114 for supply water by Twentymile Coal Company, the spoil spring did not discharge for the 1995 water year. Only one significant spoil spring at Mine 2 (a composite of two springs) was observed in 1995 and it had a conductivity of only 1040 umhos/cm. Seven additional springs with flows greater than 35 gpm were recorded at Mine 1 and Eckman Park. The flow data indicates that the spoil springs follow the same pattern as the surface runoff: very low flow during most of the year and a very rapid increase in flow during the spring runoff followed by a moderately rapid decrease in flow. EPSTE%T DOC 03/17/97 Page 6