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and subirrigation as described above. The operator had not presented any <br />information regarding the significance of the AVF to the individual farming units; <br />theretore, the AVF was considered significant for purposes of this findings <br />document. <br />The potential for impact to the AVF from mining activity is minimal, however, two <br />potential impacts have been identified: <br />1) Water which has collected in sediment ponds could infiltrate into the AVF at <br />each mine site. The potential for adverse impacts to occur is limited due to the <br />relatively small quantities of water impounded by each pond and by the <br />probability that infiltrating waters will be diluted by the great quantity of water <br />moving through the alluvial aquifer (Section G -Ground Water Hydrology of <br />this document). <br />2) The quality of the alluvial aquifer could be impacted by drainage from <br />access/haul roads which cross the AVF. It is thought that the potential for <br />significant degradation due to access/haul road drainage is minimal. This is <br />again due to the probability of immediate dilution of this drainage within the <br />AVF as discussed above. This is especially significant when considering the <br />total area of the AVF in respect to the total area of the access and haul roads <br />crossing the AVF. In any event, the impact would not cause material damage. <br />Upon examining the proposed and existing sediment control facilities at each mine <br />site, as well as data obtained from the National King Coal alluvial monitoring well, <br />the Division has determined that each site has been designed to minimize impacts to <br />the AVF. <br />Sufficient information has been supplied by the operator in regard to Pine Gulch, <br />and confirmed in the field by the Division, to make the determination that Pine <br />Gulch does not contain an alluvial valley floor (AVF) in the proposed permit area. <br />While there are limited alluvial deposits in Pine Gulch, they are not currently flood <br />irrigated for agricultural purposes and have not been cultivated historically. Due to <br />the limited surface water availability in Pine Gulch an ephemeral deposits, there <br />would appear to be no potential for future surface irrigation along Pine Gulch within <br />the proposed permit area. Additionally, there is not sufficient alluvial ground water <br />to enhance the productivity of agriculturally useful vegetation along Pine Gulch <br />within the permit area. <br />The operator has indicated that the area of confluence of Pine Gulch with Hay Gulch <br />which lies several miles beyond the permit area is an alluvial valley floor where <br />agricultural practices are being conducted. This agricultural activity, however, is <br />not dependent upon surface or ground water associated with Pine Gulch but <br />primarily upon irrigation with water diverted to the area from the La Plata River. <br />While subirrigation may also be a factor in the productivity of this area, it is the <br />25 <br />