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Effects of Mining on the Local Geomorpholoey <br />Impacts from mining on the local geomorphology will be long term, but appear to be of minimal <br />significance. The reestablished reach of the drainage which will be mined will result in a shorter, slightly <br />steeper stream channel. The potential for increased sediment loads in the drainage (once pond 007 is <br />removed) should be offset by the stable banksides and the relatively small change in overall gradient. The <br />increased runoff and consequent erosion potential on disturbed basins in the mining area due to the <br />temporary loss of topsoil stricture should be of minimal significance. Contour ripping, mulching and <br />revegetation have been demonstrated to minimize soil erosion and will be used to mitigate the increased <br />runoff potential until the topsoil structure is developed. <br />Effects of Sediment Ponds on Channel Characteristics and Downstream Users <br />Potential impacts of sediment pond 007 on downstream users will involve possible reductions in flow due to <br />impounded water. The water augmentation plan discusses the available water which will be used should <br />impacts be identified. New Horizon currently has rights to a sufficient quantity of water to supply all <br />users associated with the mining activities, plus an additional quantity of water that can be used to mitigate <br />any impact to downstream users. <br />Effects of Sediment Pond Discharee on Surface Water Ouality <br />The effects of sediment pond diversions on surface water quality will be negligible because the structure has <br />been designed to minimize impacts to the hydrologic balance. The diversion involves such minor areas of <br />disturbance that chemical and sediment changes in the flows will be unmeasurable. <br />Effects of Runoff from Reclaimed Areas on the Ouality of Streamflow <br />Due to the relatively small area of disturbance in the New Horizon 2 mining area, any reductions in runoff <br />will have only a minimal impact on streamflow quantity, as flow in Calamity Draw is dominated by <br />irrigation return flow. Decreased sediment loads predicated by SEDCAD+ indicate that reclamation efforts <br />conducted in the mining area will ensure that additional contributions of suspended sediment in runoff from <br />reclaimed areas will not occur. Effects of runoff from reclaimed areas on the quality of streamflow. Based <br />on past operating history at the Nucla Mine, no significant trend toward higher concentrations of the selected <br />parameters have been detected. In addition, the pond discharge will be monitored in accordance with <br />NPDES discharge limitations and any potential impact will be identified. Therefore, runoff from the <br />reclaimed area should have no significant impact over time on the quality of receiving stream water quality. <br />As a result, post mining land uses which currently occur in the area should not be affected due to the mine <br />plan which has been approved. <br />Summary <br />The discussion presented herein of the probable hydrologic consequences of the revised mine plan approved <br />by New Horizon identifies the potential effects of mining. Table 2.05.6(3)-1 summarizes the discussion by <br />listing the probable hydrologic consequences and the results of the analysis of each. As can be seen, all of <br />the probable impacts have been determined to be of a short term nature, of minimal significance, or a plan <br />has been presented to mitigate those determined to have some significance. As a result, mining and post <br />Page 2.04.7-33 March 2017 (TR -77) <br />