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• Effects of mining on the local geomorohologx Impacts from mining on the local geomorphology <br />will be long term, but appear to be of minimal significance. The reestablished reach of the drainage <br />which will be mined will result in a shorter, slightly steeper stream channel. The potential for <br />increased sediment loads in the drainage (once pond 007 is removed) should be offset by the stable <br />banksides and the relatively small change in overall gradient. The increased runoff and consequent <br />erosion potential on disturbed basins in the mining area due to the temporary loss of topsoil stricture <br />should be of minimal significance. Contour ripping, mulching and revegetation have been <br />demonstrated to minimize soil erosion and will be used to mitigate the increased runoff potential until <br />the topsoil structure is developed. <br />Effects of sediment fonds on channel characteristics and downstream users. Potential impacts <br />of sediment pond 007 on downstream users will involve possible reductions inflow due to impounded <br />water. The water augmentation plan discusses the available water which will be used should impacts <br />be identified. WFC currently has rights to a sufficient quantity of water to supply all users associated <br />with the mining activities, plus an additional quantity of water that can be used to mitigate any impact <br />to downstream users. <br />• Effects of sediment pond discharge on surtace water qualitx. 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 guality 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 conducted <br />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. <br />Based on past operating history at the Nucla Mine, no significant trend toward higher concentrations <br />of the selected parameters have been detected. In addition, the pond discharge will be monitored <br />in accordance with NPDES discharge limitations and any potential impact will be identified. <br />Therefore, runoff from the reclaimed area should have no significant impact over time on the quality <br />• (REVISED 9/99) 2.04.7-49 <br />