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-34- ~i Mining operations would indirectly decrease surface flows in Fish Creek by intercepting ground water now discharging to the Fish Creek stream/alluvial aquifer system. The applicant estimates (p. 2.05-49) that the mine would intercept 98 acre-feet/year of the ground water currently discharging to Fish Creek. This reduces to an average loss of 0.14 cfs from the stream/alluvial aquifer system. This compares to a low stream flow rate of 3 cfs (p. 2.04-20). Therefore, a loss of 0.14 cfs from the stream/alluvial aquifer system would not be considered significant. Finally, fallowing mining and reclamation, the underground mine workings would slowly fill with water, and ground water passing through the mine area would again discharge to the Fish Creek stream/alluvial aquifer system. Although this water would be diluted from its source concentration of 3,000 mg/1, it would be expected to add to the salt loading of the Fish Creek stream/alluvial aquifer system. However, this discharge would not be expected to significantly degrade water quality in the stream/alluvial aquifer system because of the small quantities involved (see AVF discussion, Section VII, of this document). The applicant has proposed a hydrologic monitoring plan (Exhibit 10) which includes the monitoring of receiving streams and of sediment pond discharge. As shown on the Foidel Creek Baseline Hydrology Map (Map 9a), Foidel Creek and Fish Creek will each be monitored at two locations, one above the affected area and one below. Each station will be equipped with a continuous recorder. Water quality samples will be collected weekly during the snowmelt period and monthly during the remainder of the year. These samples are to be analyzed according to the constituents listed in Table C of Exhibit lUa. This list includes most of the constituents listed in the Division's water quality monitoring guideline. Hydrologic monitoring results will be reported to the Division quarterly. Sediment pond effluent will be monitored according to the normal effluent limitations and the schedule prescribed in the operator's existing NPOES permit; weekly measurements and sampling when flow occurs. However, the Colorado Department of Health is currently amending the existing NPDES permit, and sampling of additional constituents may be required. Results of this sampling should also be provided to the Division. Stipulation No. 3 THE APPLICANT SHALL INCLUDE, AS PART OF THE QUARTERLY HYDROLOGIC MONITORIPG SUBMITTAL, THE RESULTS OF ALL HYDROLOGIC MONITORING REQUIRED BY 7HE COLORADO DEPARTMENT OF HEALTH. The applicant has not proposed a specific plan for monitoring the discharge of water from the underground workings, other than the monitoring normally required of sediment ponds. Because this discharge has a great potential of effecting surface water systems (see discussion of Probable Hydrologic Consequences - Surface Water), and because its effects on surface water quantity and quality can only be estimated prior to mining, additional monitoring of the mine water discharge is necessary.