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Section 780.21 (b) Continued. <br /> <br />Surface Water Quantity Protection <br />Potential Impacts of Mining on Surface Water Quantity <br />Mining and associated activities have she potential of creating <br />changes in the existing surface water quantity in terms of runoff <br />volumes, flow rates and direction and location of surface water <br />drainage. The potential mechanisms of impact are: 1) Filling of <br />sedimentation ponds; 2) Diversion of overland flow and ephemeral <br />streams with ditches; 3) Diversions of intermittent and perennial <br />streams; 4) Detention of surface water in pits; 5) Removal and <br />replacement of topsoil along with subsequent revegetation; 6) <br />Modification of small ephemeral drainages; and 7) Removal of <br />,existing ponds by mining. <br /> The filling of sedimentation ponds can not only decrease peak flow <br /> rates, but can also reduce the amount of water available down- <br />. stream. Diversions of overland flow and ephemeral, intermittent <br /> and perennial streams can deprive small areas of water, but will <br /> not reduce the amount of water downstream. Detention of water in <br />\ ' <br /> pits can decrease p~k <br />flow rates and can reduce the amount of <br />` <br />\ _ob <br />/ <br />water available downstream. Removal of. topsoil will increase flow <br />V` rates and runoff volume; replacement of topsoil and revegetation, <br /> as discussed in this Section under the heading of "Ground Water <br /> Quantity Protection", and as demonstrated by Lusky and Toy (1976), <br /> <br /> can result in a decrease in the infiltration rate, and thus, an in- <br /> crease in the runoff volume. Podification of small ephemeral <br /> drainages can change the location and pattern of surface water <br /> runoff and may change the rate of runoff slightly, but will not <br /> change the amount of water available downstream. Removal of exis- <br /> ting ponds can reduce the amount of surface water stored within the <br /> mine plan area. <br />No adverse effects are anticipated from increased flows and volumes <br />• other than effects on water quality, which, as discussed above, <br />780-159 <br />