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The water quality constituent concentrations from the natural springs West Buzzard, Flume, Coyote, <br />Wapiti and Cottonwood are representative of the values anticipated during low flow conditions when all of <br />the surface water is derived from groundwater discharge unaffected by mining operations. The previously <br />documented concentrations from the Colt Seep and the current concentrations encountered at the <br />Johnson Gulch and No Name springs, derived from the backfill aquifers in these areas, are higher than <br />the typical natural low flow concentrations. The groundwater being discharged to the surface from spoil <br />springs is expected to contain higher TDS concentrations for a period potentially extending several <br />hundred years after mining under the worst-case scenario as previously described. <br />These groundwater discharges are expected to increase the surface runoff water quality constituent <br />concentrations to levels comparable to those found in the backfill during periods when other sources of <br />surface runoff are not contributing significant quantities of water to the. Historic TDS and sulfate <br />concentrations from spoil springs within the project area have ranged from 1100 to 4100 mg/I and 400 to <br />2300 mg/I, respectively. Some spoil springs will exhibit elevated water quality constituent concentrations <br />for an extended period as pyrite oxidation continues to occur over the next several hundred years. The <br />relative impact to discharged surface water quality from spoil aquifers is significant during low flow <br />conditions. Typically, low flow conditions prevail for most of the year with seasonal higher flows mostly <br />associated with snowmelt runoff in April, May and June. Although higher TDS concentrations are evident <br />during the low flow periods and are important with respect to the localized flows in Johnson Gulch, overall <br />the flow magnitudes during these periods are small and of little significance to the Yampa River. The <br />Johnson Gulch base flow water quality has been affected by the backfill aquifer but these higher <br />concentrations have not affected the use of this water. <br />The water quality in the Upper Williams Fork aquifers is generally better as compared to the shallow <br />alluvium downgradient of the mine. The conductivity in the Pyeatt shallow alluvial system is <br />approximately twice the baseline value of the Third White Sandstone in the Pyeatt drainage. The spoil <br />aquifer will mainly be connected to the Third White Sandstone in this area. The initial spoil water quality <br />will likely be similar to the Pyeatt shallow alluvial system water. Trapper will continue to evaluate spoil <br />water quality through a spoil spring survey program. See Permit Section 4.8.7 for the program <br />description. <br />Water quality in natural springs is not expected to be impacted by the Trapper Mine. The water quality in <br />Fox Den spring will likely not be affected in post-mine conditions because the base of the Third White <br />Sandstone is expected to be above the recovered backfill aquifer water level in this vicinity. If the source <br />of the Fox Den spring is a deeper aquifer, no water quality effects should occur as mining will not impact <br />deeper aquifers in this area. The water quality in the North Horse Gulch spring is not expected to be <br />4-238g <br />PRO <br />g1utoot