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made a negative alluvial valley floor determination for those portions of Red Wash <br />situated within the Deserado mine permit area. <br />Past findings of the Division regarding the AVF determination for Red Wash and its <br />associated alluvium are as follows: <br />Red Wash Alluvial Valley Floor Determination <br />The Division determined that Red Wash and its associated alluvium meet the geomorphic <br />criteria, but not the irrigation requirements, of an AVF, as outlined in OSM's "Alluvial <br />Valley Floor Guidelines" established pursuant to the Surface Mining Control and <br />Reclamation Act of 1977. <br />Pursuant to Rule 2.06.8(3)(c), the Division finds that there is not sufficient water to <br />support agricultural activities. The Division therefore concludes that Red Wash is not an <br />Alluvial Valley Floor. <br />Scullion Gulch <br />Water Availability Criteria Artificial Flood Irrigation <br />As with Red Wash, flow events along Scullion Gulch were monitored using a crest stage <br />gage. During the two year inventory period conducted by the permittee, only three runoff <br />events were recorded, the highest event measuring 185 cfs. Again, crest gage data has <br />only limited application of AVF purposes. The mean annual yield estimations provided <br />by the permittee are more applicable for identifying the amount of water that may be <br />expected for Scullion Gulch. The permittee's estimations, derived using Grunsky's <br />formula, indicate that the potential average annual water yield from the Scullion Gulch <br />watershed is 202 acre feet. This corresponds to approximately 0.34 inches of runoff The <br />amount of water available annually, as estimated through this method, indicated that <br />Scullion Gulch warrants further consideration as a potential alluvial valley floor. <br />Sub - irrigation <br />As with Red Wash, the presence of sub - irrigation along Scullion Gulch was investigated <br />by the permittee based on the type of vegetation present along the drainage. The <br />permittee has identified a big sage brush - greasewood community along the entire length <br />of unconsolidated alluvial deposits identified on Map 102, and concludes that water is <br />available to the vegetation "on a limited and sporadic basis ". The big sage brush - <br />greasewood community, however, is sparser compared to that community found along <br />Red Wash, indicating the availability of subsurface water is much more limited in <br />Scullion Gulch. Further evidence of the general lack of sub - irrigation can be gleaned <br />from the permittee's surface facilities geotechnical investigation, contained in Illustration <br />18 of the permit application. Six exploration holes, sited at the proposed "D" portal area, <br />were drilled within the alluvial body associated with Scullion Gulch. Although all the <br />holes fully penetrated the alluvium, no evidence of alluvial groundwater was <br />42 <br />