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<br />Depletions in the UCRB also occur due to dead storage in ponds which do <br />not dry up seasonally. Since ponds are cleaned of sediment when sediments <br />reach 60% of design volume, average dead storage is 70% of design sediment <br />volume. Averaged over the 9 year life of the mine (from 1979 to 1987), deple- <br />tions due to dead storage equal 7.6 acre-feet per year. <br />Water is taken from Sedimentation Pond A at the rate of 20 acre-feet a <br />year for dust control (Page 779-78(a), Section 779.17 of Permit 79-177). <br />Water required for the tipple, office, shop and warehouse is pumped from deep <br />bedrock wells at the rate of 11 acre-feet a year (Page 779-78(a), Section <br />779.17 of Permit 79-177). Bottled drinking water is used at the minesite. <br />Two of the streams draining the mine, Foidel and Middle Creeks, are <br />intermittent with no year-round groundwater contribution. Fish Creek, a <br />perennial stream, receives about 25% of its inflows from groundwater (Page <br />779-71, Section 779.16(b) of Permit 79-177). CYCC believes the net effect of <br />mining on Fish Creek is increased baseflows. Recent evidence at CYCC has <br />shown that a consequence of disturbing aquifers through mining is an increase <br />in permeability, storage capacity, and specific yield. Baseflows are there- <br />fore expected to increase as a result of mining. Temporary aquifer drawdowns <br />due to mining may temporarily reduce baseflows. However, most mining is at <br />sufficient distance from Fish Creek that baseflows will not be measurably ef- <br />fected, The effect of aquifer drawdowns on baseflows is very likely small <br />compared to increased baseflows due to increased permeability. As a result, <br />CYCC believes the net effect of mining activity on Fish Creek is increased <br />baseflows. Accumulation of surface water in the mine pits will be prevented <br />by pumping water out of the pits and into sedimentation ponds as soon as it <br />begins to accumulate. <br />A summary of the effect of all mining activity authorized under Permit <br />79-177 on surface water quantity in the UCRB is found in Table 2. CYCC esti- <br />mates it is depleting streamflows by -an average of 149.3 acre-feet a year in <br />the UCRB during 1919 to 1987 due to all mining activities under Permit 79-177. <br />-3- <br />