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Reclamation has produced an increase in drainage density of 0.7 mi./sq. <br />• mi. However, drainage density of adjacent unmined areas ranges from 2.7 <br /> mi./sq. mi. to 8.2 mi./sq. mi. (Table 2.1). Approved and existing <br />drainage densities lie within this natural background range and, in <br />addition, they lie within one standard deviation of the average unmined- <br />area drainage density. <br />Reclamation has not resulted in a significant change in drainage <br />density. In fact, increasing drainage density should increase stability <br />of individual stream channels. Since there are more channels per unit <br />area, each channel will have a smaller drainage area and, therefore, <br />lower discharge. A reduction in discharge will reduce the erosive power <br />of the flow, thereby reducing channel incision. It is also likely that <br />the removal of bedrock by the mining process will increase drainage <br />density because spoil has a lower resistance to erosion relative to <br />• bedrock. The increase in drainage density due to the addition of <br />unapproved drainage ways does not constitute a significant change over <br />the approved condition and the increase may be appropriate due to <br />changes in erosional characteristics of the underlying material and the <br />increased stability afforded by the additional channels. <br />2.2.4. Natural Variations in Dip Slope Topography <br />The NOV cites the swale area at the top of the mine area as a <br />deviation from AOC. Although the pre-mine slopes within the mine area <br />appear to have been fairly uniform, the unmined dip slope northwest of <br />the mine (Section 12, Township 5 North, Range 87 West) displays <br /> <br />15 <br />