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<br />Section 785.19(c) Continued. <br />Revised 11/20/80 <br />The lithology of the stream-laid deposits in Bush, Williams and <br />Sudduth Draws are very similar, as shown on Map 40a, Kerr Mine Area <br />Stream Channel Cross-Sections. With the exception of isolated, <br />lenticular deposits of sand and gravel at the bottom of the channel <br />fill, the stream-laid deposits in all the intermittent draws were <br />found to be tight, sticky clay. In each of the intermittent draws, <br />the clay was saturated at depth, but was found to be nearly imper- <br />meable, because when the digging exposed a gravel layer, the water <br />level in the hole suddenly rose several feet. This observation <br />indicates that although the clay layers contain water, they also <br />act as confining layers by inhibiting water in the gravel from <br />being transmitted to or from the overlying stream and root zone. <br />These conclusions are supported by the following examples. <br /> <br />Water levels have been measured monthly during the baseline period <br />in three-monitor wells installed in the alluvium of the three <br />intermittent draws draining the proposed permit area. Well AO-2 is <br />located in Bush Draw, well AK-3 in [dilliams Draw, and well AJ-3 in <br />Sudduth Draw. These alluvial wells are shown on Map 15a, Kerr Mine <br />Area Ground Water Hydrology. The water levels measured in these <br />wells are plotted in Figure 29a, Kerr Mine Area Ground Water Hydro- <br />graphs. As shown in the hydrographs, the water table in Bush Draw <br />(well AO-2) and Williams Draw (well AK-3) is lowered substantially <br />in the summer months. The lack of base flow in these intermittent <br />streams and the absence of riparian vegetation indicates that the <br />water table is lowered by underflow drainage, and not by providing <br />water to the stream or root zone. The water table in Sudduth Draw <br />(well AJ-3) is shown in the hydrographs to remain at a depth of <br />approximately six feet throughout the summer months. This occur- <br />rence is due to the impoundment of water in a series of stock ponds <br />in the draw, which artificially elevate the water table in dry <br />months. <br /> <br />785-19 as <br />