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} ~'1 •l flow into the Hay Gulch Irrigation Ditch. Furthermore, it is thought that the original channel has been removed by local agricultural activities. The Hay Gulch Irrigation Ditch, which parallels La Plata County road 120, is used for flood irrigation purposes in the vicinity of present mining activity. It has been demonstrated that the naturally occurring water table of the AVF varies from above ground surface to about three feet below the surface. This demonstrated that sufficient water is available for subirrigation purposes. Furthermore, the identified land use on the AVF is primarily pastureland with occasional hay production. The essential hydrologic functions that supply water to the AVF are both flood irrigation and subirrigation as described above. The operator had not presented any information regarding the significance of the AVF to the individual farming units; therefore, the AVF was considered significant for purposes of this findings document. The potential for impact to the AVF from mining activity is minimal, however, two potential impacts have been identified: 1) Water which has collected in sediment ponds could infiltrate into the AVF at each mine site. The potential for adverse impacts to occur is limited due to the relatively small quantities of water impounded by each pond and by the probability that infiltrating waters will be diluted by the great quantity of water moving through the alluvial aquifer (Section G -Ground Water Hydrology of this document). 2) The quality of the alluvial aquifer could be impacted by drainage from access/haul roads which cross the AVF. It is thought that the potential for significant degradation due to access/haul road drainage is minimal. This is again due to the probability of immediate dilution of this drainage within the AVF as discussed above. This is especially significant when considering the total area of the AVF in respect to the total area of the access and haul roads crossing the AVF. In any event, the impact would nut cause material damage. Upon examining the proposed and existing sediment control facilities at each mine site, as well as data obtained from the National King Coal alluvial monitoring well, the Division has determined that each site has been designed to minimize impacts to the AVF. Sufficient informationhas been supplied by the operator in regard to Pine Gulch, atd confirmed in the field by the Division, to make the determination that Pine Gulch does not contain an alluvial valley floor (AVF) in the proposed permit area. While there are limited alluvial deposits in Pine Gulch, they are not currently flood irrigated for agricultural purposes and have not been cultivated historically. Due to the limited surface water availability in Pine Gulch an ephemeral deposits, there would appear to be no potential for future surface irrigation along Pine Gulch within 23