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~, CYCC Cline No. 3 Annual Hydrologic Report I. INTRODUCTION No significant changes have occurred in the hydrologic system at Mine No. 3 or in the adjacent drainages during 1986. Review of ground water quality data for the Wadge overburden aquifer indicates that more soluble NA+ and NC03 ions are being leached from the system. Calcium, magnesium and sulfate ions are becoming the dominant ions in the ground water system. Review of ground water level data indicates that wells 087758 and 087906 are continuing to recover at a 1.7 foot/year annual rate. CYCC has not consistently achieved a detection limit for cadmium that is equal to or less than the MLRD material damage criteria limit. CYCC often achieves a 20 microgram/1 detection limit, while the MLRD material damage criteria is 10 microgram/1/ Analysis of data collected from the AV series of wells at the confluence of Middle and Foidel Creeks did not provide conclusive information to the recharge and baseflow mechanisms of Foidel and Middle Creek. Installation of a stream elevation station and thorough monitoring at wells AV-1 and AV-2 should provide more conclusive information during the 1987 irrigation season. The surface water information analysis for Mine No. 3 indicates that Mine No. 3 is contributing 10 percent of the salt load in Middle Creek above site 29. The salt load contribution has resulted in an increase in Middle Creek salinity of 6 percent. CYCC has not consistently attained a detection limit for mercury in its surface water sampling program that is equal to or less than the MLRD material damage criteria. CYCC often attains a detection limit at ZO micrograms/1 for mercury that is four times greater than the 0.00005 microgram/1 (0.05 mg/1) MLRD material damage detection limit, CYCC is requested to attain a detection limit for mercury equal to or lower than the 0.00005 mg/7 material damage standard. Analysis of discharge data from site 2437, 2459 and 29 indicates that the discharge rating curve for site 29 under estimates the f]ow in Middle Creek, especially during peak flow periods. The lack of accurate flow data for site 29 makes it impossible to determine the annual water yield or salt contributions from Mine No. 3. CYCC is therefore requested to generate a discharge rating curve that accurately represents the flow in Middle Creek and is capable of determining the peak discharge at site 29.