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• -2 • 2. Rule 2.05.6(3)(b)(iv) - The applicant has provided a qualitative discussion of the probable hydrologic consequences of the mining operation which addresses runoff and erosion from disturbed areas, the sediment load from disturbed areas, the dissolved salt load in mine discharges and possible effect on Foidel Creek, and a change in the ion balance of disturbed area surface water. The applicant has not provided an assessment of other ~ssible hydrologic effects of the operation including, water quantity effects on the Foidel Creek drainage, and water quantity and quality effects on the Fish Creek drainage. The assessment of probable hydrologic consequences needs to be expanded to provide a quantitative estimate of possible effects and to analyze several additional concerns. Mine water (and possibly water from the dewatering well in Section 29) would be discharged to the Foidel Creek stream/alluvial aquifer system. The applicant should provide a worst case estimate of the quantity and quality of this discharge, and predict the effects upon surface flow regime, geomorphic stability of the stream, surface water quality, alluvial water levels, and alluvial water quality. Possible effects to downstream users of surface flow or alluvial tooter should be considered, and mitigations proposed if appropriate. The under ground mine workings would intercept ground water currently flowing toward Twentymile Park, and discharging to the Fish Creek stream/alluvial aquifer system. The applicant should provide an analysis showing the extent to which flow would be decreased in the Fish Creek system. This could be approached by first assessing the quantity and relative significance of the flow passing through the potentially affected area, and then predicting the effect of intercepting this water and discharging it to the Foidel Creek drainage. Possible effects to the downstream users of surface flow and alluvial ground water should be considered, and mitigations proposed if appropriate. The reestablishment of natural ground water movement, post-mining, would cause a plume of degraded ground water to migrate towards Twentymile Park and discharge to the Fish Creek stream/alluvial aquifer system. As a result, water quality in the Fish Creek system could be altered. The permit application contains a qualitative discussion concerning the migration of this plume, but that assessment needs to be quantified to verify the applicant's conclusions. If the quantitative assessment indicate that water quality in the Fish Creek system would be affected, possible effects to downstream users should be evaluated, and appropriate mitigations proposed.