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-22- <br /> The permittee initiated the investigation by mapping alluvial deposits along <br /> the White River, Scullion Gulch and Red Wash to determine the potential for <br /> flood irrigation capability. Vegetation indicative of subirrigated conditions <br /> were also inventoried and mapped. Along the White River, where flood <br /> irrigated cropland presently exists, inventories were made to identify the <br /> amount of acreage irrigated, the location of irrigated land parcels, and the <br /> source of irrigation water utilized. A regional flood irrigation <br /> reconnaissance inventory was conducted which included lands within about 10 <br /> miles of the mine permit area. Conclusions were then drawn by the permittee <br /> regarding the presence of alluvial valley floors within and adjacent to the <br /> mine permit area. <br /> Below is a detailed consideration of the alluvial valley floor potential of <br /> each of the following three drainages: Red Wash, Scullion Gulch and the White <br /> River. <br /> 1 . Red Wash <br /> Geomorphic Characteristics <br /> Red Wash is an intermittent stream valley which crosses the southeast <br /> corner of the permit area. Red Wash receives drainage from both the <br /> northern portion and the majority of the eastern portion of the permit <br /> area. Several minor tributaries arise within the permit area and drain <br /> eastward to Red Wash. Stock-water ponds are located in the Red Wash <br /> drainage within and adjacent to the permit area. These ponds typically <br /> catch storm runoff for use until it is lost through seepage and/or <br /> evaporation. The ponds do not contain water year round. The stream is <br /> considered intermittent because ground water discharge may enter the <br /> stream during the snowmelt season (Page II.C-18), and because Red Wash <br /> receives contributions from springs at higher elevations north of the <br /> permit area. Red Wash drains an area of 122.5 square miles, approximately <br /> 6.6 square miles of which is contained within the permit area. Red Wash <br /> enters the White River;,,approximately 1/8 of a mile below the southeast <br /> boundary of the permitarea. Map 102 shows the extent of alluvial <br /> deposits-found along Red Wash within the permit area, and to a point <br /> approximately 1/2 mile ',;upstream from where Red Wash enters the permit <br /> area. From this map, it appears the deposits are approximately 500 feet <br /> in width. Based on this map, it appears no alluvium was found along any <br /> of the tributary channels. The permittee did not quantify the amount of <br /> land area which the alluvial deposits occupy; however, based on Map 102, <br /> it appears the extent of the deposits exceeds several hundred acres within <br /> the immediate vicinity of the permit area. The deposits also appear to <br /> extend further upstream beyond the limit mapped by the permittee. Channel <br /> incision in the alluvium ranges from 5 to 30 feet. Actual thickness of <br /> the alluvium along Red '„Wash is generally unknown, as only one well , Qal -2, <br /> was drilled within the drainage. This well is located at the confluence <br /> of Red Wash and the White River. Bedrock was reached at a depth of <br /> 21 feet. The information obtained from drilling operations along the <br /> White River (inclusive 'of well Qal -2) indicate that the alluvium is up to <br /> 37 feet thick in this area, with a maximum water table depth of <br /> approximately 11 . 5 feet". Depths to water in the alluvium along Red Wash <br /> upstream from the conflluence is also unknown, again due to the absence of <br /> upstream wells in the i luvium. <br />