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• Effects of sediment ponds on channel characteristics and downstream users. Potential <br />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 <br />should impacts be identified. WFC 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 <br />mitigate any impact to downstream users. <br />Effects of sediment pond discharge on surface water auality. The effects of sediment pond <br />diversions on surface water quality will be negligible because the structure has been designed to <br />minimize impacts to the hydrologic balance. The diversion involves such minor areas of disturbance <br />that chemical and sediment changes in the flows will be unmeasurable. <br />Effects of runoff from reclaimed areas on the auality of streamflow. Due to the relatively small <br />area of disturbance in the New Horizon 2 mining area, any reductions in runoff will have only a <br />minimal impact on streamflow quantity, as flow in Calamity Draw is dominated by irrigation return <br />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 <br />runoff from reclaimed areas will not occur. Effects of runoff from reclaimed areas on the quality of <br />streamflow. Based on past operating history at the Nucla Mine, no significant trend toward higher <br />concentrations of the selected parameters have been detected. In addition, the pond discharge will <br />be monitored in accordance with NPDES discharge limitations and any potential impact will be <br />identified. Therefore, runoff from the reclaimed area should have no significant impact over time <br />on the quality of receiving stream water quality. As a result, post mining land uses which currently <br />occur in the area should not be affected due to the mine plan which has been approved. <br />Summary. The discussion presented herein of the probable hydrologic consequences of the <br />revised mine plan approved by WFC identifies the potential effects of mining. Table 2.05.6(3)-1 <br />summarizes the discussion by listing the probable hydrologic consequences and the results of the <br />analysis of each. As can be seen, all of the probable impacts have been determined to be of a short <br />term nature, of minimal significance, or a plan has been presented to mitigate those determined to <br />have some significance. As a result, mining and post mining affects to current land uses should be <br />negligible. <br />• <br />REVISED JULY 2006 2.04.7-53 <br />