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in the past and seeded recently to pasture grasses including intermediate wheatgrass and timothy. Due to the age of the stand, annual weeds were quite numerous. Based on the water level information and vegetation observations which indicate the presence of subirrigation, the Division concludes that the alluvial body in question is an alluvial valley floor. Information concerning significance of the AVF to farming has not been provided. Therefore, the Division will proceed by assuming the area is significant and will make the three required AVF findings. 1. The proposed mining operations would not interrupt, discontinue, or preclude farming on the alluvial valley floor. Proposed mining activity would not directly impact any portion of the AVF; as it is outside of the proposed Foidel Creek Mine Permit Area and would not be undermined or disturbed by proposed surface facilities. 2, The proposed mining operations would not cause material damage to the quantity and quality of surface and ground water that supply the alluvial valley floor. Since this area was designated an AVF on the basis of subirrigation, it is necessary to maintain the quantity and quality of water which supplies the alluvial ground water system. In the findings previously issued by the Division for the Foidel Creek Mine (pilot project) in 1983, it was projected (based on information available at that time that concentrations of dissolved constituents such as sodium, sulfate, iron and TDS would increase in the alluvial ground water. This effect was predicted based on the assumption that Foidel Creek surface waters affected by mine water discharge would recharge the alluvium, However, data from a recent survey of the stream channel through the alluvial body (Application Table 68) indicate the deposits underlying the channel are clays and silty clays with very limited permeability. The applicant has presented evidence that, due to the limited permeabilities, recharge of the alluvium by Foidel Creek would be insufficient (5 x 10-4 gal/day/sq.ft, of channel) to provide enough water to support subirrigation. Evidence indicates that the alluvium in the vicinity is recharged from upper Williams Fork sandstone units which occur 10-20 feet below the valley surface. As result, alluvial waters would not be impacted by the increased levels of dissolved constituents in Foidel Creek resulting from high TDS mine water discharge. 3. The proposed operation would preserve, throughout the mining operation, the essential hydrologic functions of the alluvial valley floor. The essential hydrologic functions for this alluvial valley floor have been identified as the capacity to support subirrigated -26-