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-I 5- At the maximum extent of mining operations of botA Wyoming fuel. Company and Kcir Coal Company during this permit term, approximately 200 oC the drainage area of Bolton Draw will be detained in sediment ponds. This figure is not indicative of the probable diminution of flows of Bolton Draw. Several factors play a role in mitigating the impact of mining operations on the quantity of water in Bolton Draw. They are: 1. The areas of both mine sites are generally canopied by short grasses and sage- brush. Snow accumulation in these areas is slight due to blowing conditions in North Park. The forested slopes of Johnny Moore ~~fountain provide much better conditions for Snow accumulation and probably provide a greater water. yield per acre than the mine sites. 2. Bolton Draw receives some if its water from transbasin diversion of hfichigan River waters through Spear Ditch. 3. The scenario given above assumes that a1Z of the mining occurs at once w7ren, in reality, mining will be done in phases, with portions of mined lands being re- claimed and released from the requirements of sediment control, and other areas, ahead of mining, being undisturbed. Water which does Leave the mine sites will carry a greater salt load than native surface waters due to the pumping of poor quality p.it water into sediment ponds and the evaporation of water from ponds increasing the concentration of dissolved solids. An estimate, which assumes the worst-case of 200 of the water in Bolton Draw coming from disturbed areas, is that 90.5 ky/yea z• of salt will he introduced into Bolton Draw. As Wyoming Fuel Company has never discharged water from their mine site, this estimate is highly speculative. Salt concentrations of the Canadian Strip mine over- burden are higher than overburden at the llarr Strip mine. Due to concern that pit water may eventually reach surface waters by dewateriny of sediment ponds, a stipu- lation has been included in this document Eo monitor the pz~oduction of salt from the ponds (see Bydroloyic Balance: .Surface Waters). After mining and reclamation of the affected areas, a slight increase in water yield may be expected. Infiltration tests done by f/yoming Fuel Company have shown the infiltration rate of replaced topsoil and regraded spoil to be less than the pre- existing soils. This effect should gradually decrease over time as the vegetation becomes established, increasing the depth of the rhizosphere and increasing the organic content of the soil. Both of these processes increase the infiltration rate of soils. Effects: Ground F7ater Both the Wyoming Fuel and Kerr mines are located on the flanks of the McCallum Anti- cline and the Johnny Pfoore Syncline, and thus, are hydrogeologically adjacent. The Bourg mine is outside of the ground water basins of these mines. The Wyoming Fuel mine is mining south and west around the nose of the hcCallum Anticline, whereas the Kerr mine is mining north and east around the nose of the Johnny Moore Syncline. Ground water flow from both the Kerr and Wyoming Fuel mines is down the dip of the McCallum Anticline to the axis of the Johnny hfoore Syncline.