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-17- Based on the information provided by the applicant, the upper area is found not to be an alluvial valley floor. Downstream from the water gap, the Foidel Creek valley again widens out, and a second area of unconsolidated streamlaid deposits is found in Sections 21, 22 and 28 (T5N, R86W). The application does not identify any historic or existing flood irrigation in this area. Streamflow in this area is still intermittent, and the area would not be capable of _ ~lond_ir_ri.gation implementing the methods IICPd i.n_adjaCent r37-ndge . The applicant has not provided hydrologic or vegetative information sufficient to determine the presence or absence of subirrigation. / Therefore, the Division must take a conservative approach and assume that / 'the area is subirriaa- _ ' Based on the information provided by the applicant, the second area of / unconsolidated streamlaid deposits is found to be an alluvial valley floor because of its capability to support subirrigated agricultural activities. No information has been provided concerning the significance of the alluvial valley floor to farming. Therefore, the Division must proceed by assuming that this area is significant to farming and by making all three alluvial valley floor findings. 1) The proposed mining operations would not interrupt, discontinue, or preclude farming on the alluvial valley floor. No mining activities would take place within or beneath the alluvial valley floor itself. 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 alluvial valley floor because of suoirrigation, it is necessary to maintain the quantity and quality of water which supplies the alluvial ground water system. The continuous discharge of underground mine water into Foidel Creek will have the effect of maintaining the water table in the alluvium at the level established in the spring runoff season. The maximum amount of discharge (650 gpm) is expected to raise alluvial water levels about 5 feet and maintain the water table at the elevation of the streambed throughout the year during mining operations. This effect will probably be felt downstream to the confluence with Middle Creek. The impact of raising the water table in the alluvium will not be adverse; in fact, a higher water table may benefit vegetative production in the floodplain downstream from the mining operations by supplying continuous moisture to the root zone. The quality of underground mine effluent is expected to be somewhat less than that of baseline surface water quality. Concentrations of dissolved elements such as sodium, sulfate, iron, and total dissolved solids will be increased, and the effluent released to the stream will infiltrate into the alluvial water system. However, due to mixing with natural runoff and alluvial waters, the concentration of TDS in the effluent (800 mg/1) is expected to be diluted. Water having total dissolved solids concentrations of 800 mg/1 would not have a detrimental effect on most crops ( EPA, 1976, p.208).