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The estimated quantity of mine water discharged this year averaged 0.007 cubic feet per second <br />' (CFS), The average flow rate of the White River is 672 CFS resulting in a dilution ratio of about <br />96,000 to 1. The discharged water was within effluent limits during this water year. <br />' The decline in piezomefic levels in bedrock zones 'upper sandstone fades', 'siltstone/coal fades', <br />and 'lower sandstone fades' was anticipated as probable impacts as the result of underground <br />' mining activities. As projected these impacts are localized and will most probably continue in the <br />proximity of the mined area. <br />' As projected, subsidence in Red Wash initially resulted in water ponding in the stream bottom. <br />The high content of silt and clay carried by Red Wash rapidly fills the ponds. The silt and day <br />' layers have sealed any cracks that formed in the alluvium as the result of subsidence. Water <br />continues to flow in the surface channel at Red Wash indicating that the basal alluvium is not <br />recharged by surface flow infiltration. <br />' 3.3 Slgnltlcance of Impacts to Use of Water <br />The current rate of withdrawal of water from the lagoon in the White River alluvium is tar below <br />that projected at Tull production. Based on the current level of production and the current rate of <br />' withdrawal, Western Fuels is not likely to exceed the projected withdrawal rates even at higher <br />production levels. <br />During this reporting period, lowering of the piezometric level in the 'upper sandstone fades' (at <br />2-17U) and the 'middle siltstone/coal fades' (at 35-4M) was noted. The significance of these <br />' impacts are minimal as no beneficial use of the bedrock ground water exists in the Deserado Mine <br />area. At the same time, the piezometric level showed gain in wells 36-2U, 4-20U and 36-2L <br />Water levels in other wells remained unchanged. <br />' Water ponding in Red Wash as the result of subsidence over longwall panels No. 1, No. 2, No. <br />3, No. 4, No. 5, 6 and No. 7 acted as stilling basins for deposition of clays and silts being carried <br />down Red Wash. The significance of this impact is beneficial as the sediment load to the White <br />River was reduced. The same impact is expected as a result of subsidence over subsequent <br />longwall panels. <br />' 3.4 Etfectlveness of Mltlgatlon Measures <br />Mitigation measures at the Deserado Mine primarily include impoundment structures to control <br />runoff from surface sites and coal reiuse piles. These structures have worked well as no <br />discharges of runoff and possibly contaminated water from these impoundments have occurred. <br />' Reclamation of areas disturbed during construction and operation is effective in controlling both <br />erosion and suspended solids during runoff events. Sediment control structures such as banns, <br />ponds and sediment fences are used to control run off from disturbed areas until vegetation and <br />' the natural contours are reestablished. <br />' 19 <br />