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• downstream increase was again apparent during the 1999 water year. 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 with springs measured for flow and field parameters. If a spring is discharging 35 gallons per minute or greater, it is monitored throughout the remainder of the year in accordance with the monitoring plan. The field data for the 1999 spoil spring monitoring program is presented on Table 30. A plot of the historic flow data for Pond 87 and spoil spring 114 is presented on Figure 64. No discharge from the spring was observed during the spring. Discharge from Pond F ceased by the end of June. Three springs with flows greater than 35 gpm were recorded at Mine 1 and Eckman Park. Spring D Comp serves as a composite sampling point for the A, B, and C series springs at Eckman Park above Pond A. 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. 1999 water quality data for spoil springs which were sampled for water quality are presented • on Tables 31 through 40. Tables 31a through 40a provide period of record statistical summaries for the monitored sites and Tables 31b through 40b provide period of record flow summaries for the sites. The data for the Mine 1 spoil springs shows a maximum field conductivity value of 2540 umhos/cm (Spring 1861550) during the 1999 water year. Spring 114 is typically the dominant influence in this area during the Annual Spring Survey. However, at the time of the survey this spring, like many others, was not flowing. The data for the Eckman Park spoil springs show a maximum field conductivity value of 3940 umhos/cm (1860210) during the 1999 water year. During the winter when Foidel Creek flows are dominated by spoil spring discharges, the creek's conductivity level approaches that of the spoil springs. The conductivity of the spoil springs shows temporal fluctuations that most likely reflect spoil recharge events of low TDS snowmelt. The lowest TDS concentrations in the spoil springs typically occur during the Spring snowmelt period. Figure 70 indicates that the water quality in Foidel Creek (Site 8) is influenced by the water quality of the discharge from Pond A. Pond A receives the discharge of the largest spoil springs. The spoil spring 114 discharge, which feeds site 87 (Pond F) is characterized by high dissolved solids, calcium, magnesium, sulfate and SAR compared with bedrock groundwater, other spoil springs and unaffected surface waters. Station 114 also shows comparatively high manganese and high nitrate levels. Spoil spring discharges as measured from Mine 1 and Eckman Park totaled approximately 2.06 cfs during the spring survey of 1999. • cycc99 02/14/00