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<br />_2P_ <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 permit area. 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 pennittee. 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 aiong 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 confluence is also unknown, again due to the absence of <br />upstream wells in the alluvium. <br />